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WÊÊSSÊÊ•JV-V:= Modifications, Corrections and Revisions to the Animas UAA
Several replacement pages to the UAA are included in this mailing. The plastic binder can be easily be opened by hand if you don't have a binder contraption. Remove original page(s) and replace with new.
The following is a summary of the changes we have implemented.
Chapter 8
The Ac/Ch Standards.xls workbook (previously Ac_Ch TVS.xls), Appendix 8-B, was modified to reflect the WQCD’s most current equations.
Figures 8.16 and 8.17, which compare dissolved and total metal concentrations using the WORM, were revised to correct an error in copying formulas for iron, D/T_Fe.xlsf and zinc D/T_Zn.xls, The DissJTot Folder is a part of the Appendix 8-C. Formula errors in for cadmium, D/T_Cdxls, and manganese, D/T_Mn.xls, were also corrected; however these two metals were are not depicted in figures 8.14 through 17.
Chapter 11
M18C, described as the 1st SW Drain-MF Min, was deleted from Table 11.1, Metal loads from selected adits in the Upper Animas Basin. This site is the “red tributary.” It was incorrectly classified as a mine adit. Phase 1 reduction scenarios for aluminum and iron shown in Figures 11.1a and 11. Id were modified to reflect removing M18C as an adit source. Deleting this source also affected concentrations shown in Figures 11.2a and lL2d.
Table 11.3, Summary o f metal loads from adits and combined mine waste for the Animas River Basin above A 72, was modified to account for removing 1 SW Drain- MF Min as an adit source of metals. The text of pages XI-2, XI-6, & XI - 7 have revised to reflect that Table 11 1 now contains only 33 (rather than 34) of a total of 133 (rather than 134) draining adits which accounts for 89% of adit loads (rather than 91%).
A waste load reduction scenario that considers the impact of zinc loading to the Animas River from undetermined sources between A53 and A68 was developed. The load analysis is based on stream flow and water chemistry at A53 and A68 between August 1998 and August 1999. Results of the load analysis are contained in the workbook A53 A68 Loadxls. The zinc load from undifferentiated sources approximates zinc loads from all adit sources in the basin. The result of removing this undifferentiated zinc load, represented as Zn concentrations at A68 and A72, is presented in the workbook entitled A53_A68 Redxls. • Table 12.1 a-f has been slightly modified to reflect newly adopted Table Value Standard equations and corrections to the anticipated reductions from draining adits.
• The title to Table 12.2 has been changed from 85% pH to 15% pH to reflect correct percentile used for pH standards
• Table 12.4 has been modified to reflect coiTected values for stream standard and temporary modification recommendations resulting from changes in Table 12.1.
Additional Analyses Recently Being Developed includes:
• Cumulative Remediations Reductions and Costs from Adits
• Cumulative Remediation Reductions and Costs from Mine Wastes
• Metal Loading Analysis for Animas river between Howardsville and Silverton
These will be made available at regularly scheduled ARSG meetings or upon request. Figure 8.16 Comparison of total recoverable and dissolved iron concentrations and the cyclical variation of pH at stream gages in the upper Animas Basin. Animas at Silverton, A68, is not shown because most observations of dissolved iron are less than detection. Animas River at Silverton, A68 Cement Creek CC48
Month Month
ToM R e c o v ------Dis ♦ pH { Totd R e c o v ------Oissotod ♦ pH
Mineral Creek, M34 Animas River below Silverton, A72
Month Month Total R e c o v ------aâsd v etl ♦ pH { TeW R e c o v ------D ssd w d ♦ pH
Figure 8.17 Comparison of total recoverable and dissolved zinc concentrations and the cyclical variation of pH at stream gages in the upper Animas Basin. Legend Figure 8.20a Seasonal, flow-basedqualityregression sources oftotal model. recoverable aluminum Streamflow and the is iron toaverage Mineral monthly Creekflow nearat M Silverton, 34,1993 estimatedto 1999.from the water Calculated values arefor the day of15th each month.
V I I - 4 7 Figure 8.20b Seasonal, flow-based sources of total recoverable cadmium, copper, manganese, and zinc to Mineral Creek near Silverton, estimated from the water quality regression model. Stream'flow is the average monthly flow at M 34,1993 to 1999. Calculated values are for the 15th day of each month. CHAPTER XII - RECOMMENDATIONS
The recommendations of this report are based on a combination of four components of the UAA - the biological assessment, the water chemistry assessment, the limiting factors analysis, and the remediation analysis. Most of the recommendations are directed to the Colorado Water Quality Control Commission (WQCC), but a few are aimed at other stakeholders: the San Juan Board of County Commissioners, U.S. Forest Service, and the U.S. Bureau of Land Management. The recommendations for WQCC lie in three areas, segmentation, use classifications and water quality standards.
CHANGES IN SEGMENTATION
While the UAA has focused on stream segments in the Upper Animas Basin that have impaired water quality, many small tributaries to Mineral Creek and the Animas River can meet cold water aquatic life class 1 Table Value Standards (TVS). Some of these small streams have improper or non-existent use classifications and standards. For example, about nine small tributaries to the Animas River from Maggie Gulch to Elk Park (tributaries to Segments 3 a, 3b, and 4a), have been inadvertently omitted from descriptions of any segment and therefore have no applicable use classifications and standards. Several tributaries to the upper part of Mineral Creek have no aquatic life classifications, yet they are located in non-mineralized areas and have very good water quality. To bring the omitted segments under regulatory compliance and to more accurately portray the current water quality situation, it is proposed that all tributaries to the Animas River from Maggie Gulch to Elk Park be placed under one segment description, segment 6, with exceptions made for those areas that do not meet TVS for aquatic life class 1. The exceptions fall under:
segment 7, the drainage of Cement Creek, segment 8, Mineral Creek above South Mineral Creek including tributaries on the east side of the creek except for Big Horn Creek, and the Middle Fork of Mineral Creek, segment 9, Mineral Creek from South Mineral Creek to the Animas River, currently called segment 9b. Segment 6, therefore includes tributaries to Mineral Creek on the west side of the drainage, which is outside the caldera, except for the Middle Fork of Mineral Creek. It includes’the South Fork of Mineral Creek and Big Horn Creek which is only tributary included on the east side of Mineral Creek. The differences in water quality between streams in segment 6 and those in segments 7, 8, and 9 are closely tied to differences in geology of the areas those streams drain. technology that could be used and the size and complexity of site. Accessibility affects both cost and the remediation technique selected.
As discussed in Chapter X, the cost analysis is a first approximation and uses four cost categories, each with a broad numerical range. The costs for remediation for each site listed in Table 11.1 below is the mid-point of the range for each cost category. One million dollars was used as an estimate for sites whose costs are greater than $500,000. These cost estimates do not include engineering design, operation, or maintenance costs that may be needed.
Loading from the Largest Adit and Mine Waste Sources
The adits have been ranked, using the weighting factors discussed in Chapter 10, on the basis of both high and low flow loading of seven metals plus pH. Most high flow samples were obtained in June or July, while low flow loads were obtained in September or October. These figures may overestimate low-flow loading since early fall stream flows had not yet dropped to levels seen in winter months. Loads from the Kohler, Bandora, North Star, and Evelyn mines were sampled frequently.
Selection of sites to be included for possible remediation is based upon the combined rankings of all sites within the Upper Basin (Appendix 10E). Many sites were previously categorized as "no action" because of their low total contributions and remoteness and/or low concentrations. The loading from the top ranking 33 adits, including a few large loaders lacking either a high or a low flow sampling datum, are displayed in Table 11.1. These are current loading figures and do not include any potential reductions. Eighty nine percent of the loading from all adits comes from these top 33 sites.
Mine waste piles have been ranked in a similar fashion as adits including the same weighting factors, except that they are ranked by metal concentration determined by the leach test instead of load (Appendix 11 A). Table 11.2 lists the top 26 mine waste sites plus an additional six sites which were added because of their large size and therefore potential for significant load contributions. Leachate concentrations presented in Appendix 10E have been converted to "potential loads". The annual load contributed from waste rock site in Table 11.2 was estimated by multiplying the concentration from the leach test of the waste rock times the surface area of the pile times the average annual runoff from the basin expressed as depth (29 inches). The potential load figures do not include any potential reductions.
The 32 waste sites listed contribute 90% of the estimated load from all 158 sites. Units are in pounds per year as opposed to pounds per day used for adits. Estimated loading from mine waste is much smaller than from adits. Approximately eighty-five percent of the mine-related annual metal load in the Upper Animas Basin is from adits, and fifteen percent is from mine waste.
As with adits, the appropriate site treatment and corresponding load reductions are based on professional judgement. Again, the estimated costs of remediation fall into the same four categories used for adits. The costs listed in Table 11.2 are the mid-point of the ranges of each category applied to the particular site.
Sites with CPDES or reclamation permits are not included in the tables in this chapter. It is assumed that required best management practices and/or treatment at these sites is already in place. Pounds per day High Flow Low Flow Mine Phase 1 % Cost $ Al Cd Cu Fe Mn Zn AI Cd Cu Fe Mn Zn Removal 1000's Cement Creek Mogul 80% 1000 1 0.04 1.7 14 4 2 1 0.02 0.7 5 1 3 Silver Ledge 50% 300 25 0.09 0.6 222 33 15 4 0.03 0.0 56 11 3 Grand Mogul 0% 60 15 0.15 5.3 33 10 27 I 0.01 0.2 0 0 1 Mammoth 30% 60 1 0.00 0.0 14 2 8 1 0.00 0.0 16 2 0 Anglo-Saxon 30% 60 0 0.00 0.0 15 10 2 0 0.01 0.0 15 S 1 Joe & Johns 30% 300 0 0.00 0.2 1 1 1 0 0.00 0.0 1 0 0 Big Colorado 50% 300 1 0.00 0.0 3 3 0 1 0.00 0.0 6 0 0 Porcupine 30% 60 0 0.00 0.0 14 5 1 0 0.00 0.0 10 5 1 Evelyn 50% 1000 1 0.00 0.0 2 0 0 2 0.00 0.0 3 0 0 Lewis property 50% 60 0 0.01 0.4 2 0 1 0 0.01 0.4 2 0 1 Total Cement Creek 44 0.29 8.3 320 68 57 10 0.07 1.3 113 25 12 Mineral Creek Kohler 50% 60 33 0.36 30.7 321 10 91 28 0.25 28.3 264 8 78 North Star 50% 300 0 0.02 0.1 6 16 4 1 0.02 0.2 6 11 3 Junction Mine 50% 300 13 0.07 2.2 126 3 14 0 0.00 0.1 3 0 0 Bandora Mine 30% 60 0 0.04 0.1 5 4 10 0 0.02 0.0 2 2 4 Upper Bonner 50% 300 1 0.00 0.0 1 1 1 2 0.01 0,0 ? 1 1 Ferrocrete Mine 50% 300 2 0.00 0.0 31 5 1 3 0,01 0.0 32 7 1 Paradise 0% 60 28 0.00 0.1 246 20 2 28 0.00 0.1 2.46 20 2 Brooklyn Mine 30% 300 1 0.01 0.2 8 2 2 1 0.01 0.2 8 7 2 Bonner Mine 50% 300 1 0.01 0.0 1 1 1 2 0.00 0.0 2 1 0 Lower Bonner 30% 300 1 0.00 0.0 1 0 0 2 0.00 0.0 2 1 1 Little Dora 50% 300 1 0.33 0.9 5 653 48 0 0.00 0.0 0 2 0 Total Mineral Creek 81 0.85 34.3 751 715 175 65 0.31 28.9 566 54 93 Animas above Eureka Vermillion Mine 50% 300 0 0.04 0.2 2 1 9 0 0.01 0.1 1 0 3 Columbus 50% 300 1 0.01 0.3 3 0 9 0 0.02 0.1 1 0 4 Lower Comet 0% 10 2 0.00 0.1 2 2 1 2 0.00 0.0 1 1 1 N side of Calif. Mtn. 30% 60 4 0.01 0.0 1 5 2 4 0.01 0.0 1 5 2 Sound Democrate 50% 60 0 0.00 0.1 0 4 1 0 0.00 0.0 0 2 0 Mountain Queen 50% 300 0 0.00 0,2 1 0 1 0 0.00 0.1 0 0 0 Silver Wing 30% 0 0 0.00 0.1 0 0 0 0 0.00 0.3 1 1 1 Bagley 30% 300 0 0.01 0.0 0 13 7 0 0.01 0.0 0 6 3 Senator 30% 300 0 0.00 0.0 21 7 ‘0 1 0.00 0.0 23 14 2 ' Total Animas above Eureka 8 0.08 1.0 30 33 29 8 0.06 0.7 29 29 15 Animas below Eureka Royal Tiger 50% 300 5 0.04 0.8 0 3 7 0 0.00 0.1 n 0 0 Pride of the West 30% 60 0 0.01 0.0 0 0 3 0 0.01 0.0 0 0 ? Little Nation 30% 300 0 0.00 0.0 9 2 1 0 0.00 0.0 4 1 0 Total Animas below Eureka 6 0.06 0.8 9 5 10 0 0.02 0.1 4 2 3 Grand Total 138 1.29 44.5 1110 822 271 83 0.45 31.0 712 109 124
No low flow data. Low flow loads are extrapolated from high flow data No high flow data- High flow loads arc extrapolated from low flow data Revised 3/5/01 Basin Load in pounds per year Mn Zn Site Name Acres % Reduction Cost Ai
Using the information from Tables 11.1 and 11.2 and Appendix 11 A, the results of several different remediation scenarios can be estimated. The scenarios shown on Table 11.3 include phase 1 treatment of the top 33 adits and of the top 78 adits, phase 2 treatment of the top 33 adits and of the top 78 adits, phase 1 treatment of the top 32 mine waste piles and of the top 127 mine waste piles. Costs listed under phase 2 include the costs of both phase 1 and phase 2 treatments since phase 2 would not be implemented until after phase 1 had been tried.
For the adit scenarios, loading figures are derived from low-flow samples because that time period is of most concern. Out of 174 adits sampled, only 133 had measurable drainage during low-flow samplings.
The cost estimates listed on the tables above and in Appendix 11A do not include engineering design, operation, or maintenance costs. Remediation experience in the Basin has shown that administration costs are substantial and cost overruns have been encountered owing to larger than expected volumes of material or other unanticipated problems. The scenarios listed below include a 30% administration cost and a 20% contingency cost added to the sum of the individual site costs.
Table 11.3 Summary of metal loads from adits and combined mine waste for the Animas Basin above A72.
Total load of Al, Cd, Cu, Fe, Mn and Zn in pounds/year Top 33 386,741 Top 32 79,429 133 Adits 434,547 Top 158 88,602
Estimated cost to remediate in $1000’s Phase 1 Phase 2 Option 1 Top 33 $ 12,105 $ 20,550 Top 32 $ 8,175 Top 77 $ 20,550 $ 31,830 Top 127 $ 21,960
Load Removed in pounds/year Phase 1 Phase 2 Option 1 Top 33 128,041 194,275 Top 32 50,494 Top 77 138,834 208,945 Top 127 54,618
Cost pound/year Phase 1 Phase 2 Option 1 Top 33 $ 94.54 $ 105.78 Top 32 $ 161.90 77 Adits $148.01 $152.34 Top 127 $ 402.10 ♦Total cost divided by load removed Clearly there are diminishing returns in treating both adits and mine waste. The top 33 adits account for 91% of the load and under phase 1, it would cost $12.5 million to treat them. To treat the additional 9% of the load would add $8.5 million. The contrast is more stark under mine waste. The top 32 sites account for 90% of the load and would cost just over $8 million to treat. Treating the additional 10% would add almost $14 million.
The phase 2 adit scenario includes removal of large quantities of Fe and A1 from the Paradise portal. In fact, 81% of the difference in load removed between phase 1 and phase 2 for adits can be attributed to phase 2 remediation of the Paradise alone. Under phase 1, no reductions in metals from the Paradise are anticipated because a more thorough investigation of the site will be the first step. With the exception of this one site, there is little difference in reductions of metals between phase 1 and phase 2. Moreover phase 2 would only be implemented if phase 1 did not result in projected reductions. Therefore, without the Paradise and its associated phase 2 remediation cost of $1 million, the difference in costs between phase 1 and 2 can be thought of as a range of costs associated with a total loading reduction for adits of approximately 170,000 to 180,000 pounds per year.
Remediating the Paradise portal along with two other similar sites, the Ferrocrete mine, and a small prospect on the Middle Fork of Mineral Creek is problematic. They are all shallow workings in the Mineral Creek drainage and lie near the base of valleys. The mines are thought to have intersected the relatively shallow groundwater that wells up at valley bottoms creating the area’s infamous iron seeps and bogs. Metal loading may well be the result of natural geological processes that is carried into the mine through groundwater infiltration. While treating naturally occurring source loads (coming from adits) may be beneficial, discharges with high iron and aluminum concentrations are expensive to treat because of high production of sludge which needs disposal plus frequent system maintenance. These adits are also collapsed, indicating that they were constructed in highly fractured rock making it unlikely that bulkhead seals would provide significant reductions. Successful remediation of these sites would be very difficult and expensive.
EFFECTS OF REMEDIATION ON WATER QUALITY
Figure 11.1 shows the estimated reductions of the six priority metals at the four gages if remediations were implemented on the top 32 mine waste piles and phase 1 remediations were implemented on the top 33 adits. Figure 11.2 shows estimated reductions if remediation were implemented on the top 32 mine waste piles and phase 2 remediations were implemented on the top 33 adits. The description below summarizes the results.
BTect of Remediation on Total Recoverable Iron a t M34
Month
C M 34 ------NewCcnc
Effect of Remediation on Total Recoverable Ztnc at A72
Month
• C A 7 2 ------N ew C one
remediated
E ffe ct o f Remediation on Total Recowrabie Iron at A68
o - JFMAMJJAS 0 ND M o n th
|------C A 6 8 ------New Cone | BTect of Remediation on Total Recoverable Manganese at M34 3000
2 50 0
2000
1500
10G0
500
0 J FMAMJ JASOND M o n th
------C M 3 4 ------N e w Cone are also converted to dissolved values. The last column shows TVS values for the different metals.
The numbers in bold are the recommended standards. Generally, the standard is equal to which ever is greater, the dissolved concentration after remediation or TVS.
Wherever the standard is equal to the remediation concentration, a temporary modification will be needed. They are noted on the table with a TM. It is proposed that the temporary modification be set equal to the current ambient concentration as shown on Table 12.1 for a period of six years. After six years, progress of remediation and resulting changes in water quality should be re-evaluated.
Since metal concentrations in Cement Creek are expected to rise when Sunnyside Gold turns off its treatment plant at the American Tunnel in compliance with the consent degree, the proposed ambient water quality has been modeled using data from before Cement Creek was treated. These concentrations are designated on the table with “Pre- CD”. Revised Revised 3/5/01 Stream Season Month (s) of highest Total Peak month % Month (s) of Max. Peak month % TVS for same Segment Concentration value dissolved; concentration and value dissolved; month and location before remediation icuirent dissolved after remediation (Dissolved Conc. (ch=chronic; (Total conc. values) • Concentration] (Total conc. values) Potentially ac=acute) Attainedl A68 Low Flow April @ 232 0%; [0] April @ 222 0%; [0ug/l] TVS (ch) = 87 (Sept - April) TVS (ac) = 750 High Flow May @ 213 0%; [0] May @ 210 0%; [0 ug/1] TVS (ch) = 87 (May - August) TVS (ac) = 750
M3 4 Low Flow Feb. @ 4376 56%; [2451] - Feb. @ 4225 56% ; [2366] TVS (ch) = 87 (Sept - April) TM TVS (ac) = 750 High Flow Aug. @ 1523 15%; [229]- August @ 1487 15%; [223] TVS (ch) = 87 (May - August) TM TVS (ac) — 750
CC48 Low Flow Feb. @ 6101 100%; [6101] Feb. @ 6038 100%; (6038) Ambient (Sept. - April) High Flow Aug. @2932 99%; [2903] August @ 2883 99%; (2854) Ambient (May - August)
A72 Low Flow Feb. @ 3055 24%; [733] - Feb. @ 2982 24%; [716] TVS (ch) = 87 (Sept - April) TM TVS (ac) = 750 High Flow May @ 839 03%; [25] May @ 826 3%; [25] TVS (ch) = 87 (May-August) TVS (ac) = 750
A75 Low Flow Little Al. data TVS (ch) — 87 (Sept - April) No exceedances TVS (ac) = 750 High Flow Little Al. data TVS (ch) = 87 (May - August) No exceedances TVS (ac) = 750
Note: Dissolved / Total ratios are zero in some instances because the majority of samples were below detection for dissolved Al. (all values in ug/1 unless otherwise noted) Bold = Recommended Stream Standard; TM — Temporary Modifications Needed Stream Season Month (s) of highest Total Peak month % Month (s) of Max. Peak month % TVS for same month Segment Concentration value dissolved; concentration and value after dissolved: and location before remediation [current dissolved remediation (Dissolved Conc. (ch=chromc; (Total cone, values) Concentration] (Total conc. values) Potentially ac=acute) Attained) A68 Low Flow April @2.7 97%; [2.6] April @2.6 97%; [2.3] TVS (ch) = 2.9 (Sept. - April) TVS (ac) = 5.5 High Flow May @ 2.3 97%; [2.2] - May @2.2 97%; [2.1] TVS (ch) = 2.0 (May-August) TM TVS (ac) = 3.1
M3 4 Low Flow April @ 1.4 97%; [1.4] Oct. @ 0.6 97%; [0.6] TVS (ch) — 3.6 (Sept - April) TVS (ac) = 8.0 High Flow May @ 1.0 97%; [1.0] May @0.7 97%; [0.7] TVS (ch) = 2.0 (Mav - August) TVS (ac) = 3.0
CC48 Low Flow Sept. @ 2.8 97%; [2.7] Sept. @ 2.2 97%; [2.1] Ambient (Sept. - April) High Flow June @ 3.2 97%; [3.1] Aug. @ 2.4 97%; [2.3] Ambient (May1 - August)
A72 Low Flow April @2.4 97%; [2.3] 97%; [1.8] TVS (ch) = 3.7 (Sept- - April) TVS (ac) » 7.7 High Flow May @2.2 97%; [2.1] 97%; [1.7] TVS (ch) = 2.1 (May - August) TVS (ac) = 3.3
A75 Low Flow TVS (ch )- (Sept. - April) TVS (ac) = High Flow TVS(ch)® (Mav - August) TVS(ac) = 3c Yearly TVS(ch) = Arrastra TVS(ac) = Note: Cadmium dissolved / total ratios difficult to ascertain because of numerous samples were below detection, lab. detection limit variability, and the numerical difference between detection limit and normally toxic levels is quite small. TVS TVS (ch)-1 2 TVS (ac)~19.0 TVS forTVS monthsame locationand (ch=chromc; TVS (ac) =11.6 ac=acute) TVS (ch) = 8 TVS TVS (ac)= 29.0 TVS TVS (ch) = 14 TVS TVS (ch) = 8 TVS (ac)= 15.0 Ambient TVS (ac)- 25 TVS (ac)= 12 TVS (ch) TVS (ac) TVS (ch) TVS(ac) TVS TVS (ch) = 4 TVS(ch)=4.9 TVS (ac)=6.9 [Dissolved Conc. 42%; [9] Peak% month dissolved; Attained] Potentially 49%; [10] 49%; [8] 29%; [10] 86%; [46] Ambient 30%; [9] TVS (ch) = 8 26%; [8] *1« Month (s)Month Max. of concentrationvalueand after remediation (Total conc. values) Mar. April& 21 @ April @ 16 May @ @ May 19 May @32May April @27 July & AugustJuly 69 @ 95%; [66] May @ @ May 30 W k/MUlUUlUj (currentdissolved TM Peak month % % Peak month dissolved; Concentration] 27%; [7] 50%; - [10] TM 100%; [90] 100%; 66%; - [45] 29%; [13] 29%; - [13] TM 86%; [55] @ 53 Sept. 30%; - [15] TM TM No No exceedancesexceedances No No exceedances No exceedances June @6 Concentration valueConcentration (Total conc. values) Month(s) of highest Total before remediation March @23 May @20 Mar. @67 May @44 May Sept. Sept. @ 64 July @ July@ 90 April@49 May @37 26%; - [10] June @8 Season (May - August) (Sept - April) Low Flow (Sept. - April) High Flow Low FlowLow (May-August) HighFlow (Sept. April)- (May-August) (Sept April)- (May-August) Low FlowLow High Flow (May-August) Low FlowLow High Flow (Sept.-April) High Flow Low FlowLow yearly Stream Segment A68 M34 CC48 A72 A75 3c Anastra n
XII- O Stream Season Month (s) of highest Total Peak month % Month (s) of Max. Peak month % TVS for same Segment Concentration value dissolved; concentration and value after dissolved; month and location before remediation icurrent dissolved remediation IDissoived Conc. (ch=chronic; (Total conc. values) Concentration] (Total conc. values) Potentially Attained! ac=acute) A68 Low Flow March @ 2435 100%; [2435] - March @2379 100%; [2379] TVS (ch) = 2016 (Sept. - April) TM TVS (ac) — 3689 High Flow May @ 1216 87%; [1058] May @ 1207 87%; [1050] TVS (ch) = 1553 (May-August) TVS (ac) = 2838
M34 Low Flow Feb. @ 536 100% [536} Feb. & Mar. @397 99%; [397] TVS (ch) - 2139 (Sept. - April) TVS (ac) — 3916 High Flow Aug. @ 199 96%; [191] May @48 96%; [46] TVS (ch) =* 1557 (May-August) TVS (ac) = 2844
CC48 Low Flow Nov. @ 1984 90%; [1786] Dec. @ 1827 92%; [1681] Ambient (Sept. - April) High Row Aug. @ 987 100%; [987] May @896 85% [762] Ambient (May7 - August)
A72 Low Flow March @ 1423 94%; [1338] March @1337 94%; [12571 II II II ÍÍ (Sept. - April) s s High Flow May @691 74%; [511] May @631 74%; [467] TVS (ch)« 1598 (Mav - August) TVS (ac) = 2892
A75 Low Flow No exceedance No exceedance TVS (ch) (Sept. - April) TVS (ac) High Flow7 No exceedanee No exceedance TVS (ch) (May - August) TVS (ac) 3c Yearly (only 5 No exceedance No exceedance TVS (ch) Arrastra samples avail.) TVS (ac) TVS for same TVS andlocationmonth (ch=chronic; ac=acute) (ch)TVS = 1000 TVS (ch)=TVS 1000 TVS =(ch) TVS 1000 =(ch) TVS 1000 Ambient Ambient (ch)= TVS 1000 (ch)= TVS 1000 TVS TVS (ch)= 1000 (ch)TVS = 1000 [Dissolved Conc. Conc. [Dissolved Attained] Peak % month dissolved; 19%; Potentially NA; 51%; NA; 66%; 50%; 50%; 38%; — ------r concentrationvalueandafter (Total values) conc. April@641 Month (s) of Max. Month (s) ofMax. remediation Jan. & Feb. Jan. & Feb. @3547 May @624 Aug. Aug. @2734 Jan. 9230 @ Feb. Feb. 4195 @ Too littleToo data May @1865 Too little data %; fcuirent dissolved 1%; Peak month% dissolved; Concentration] 50%; NA; NA; 66 50%; 4983 May @ 50%; (Total conc. values) Concentrationvalue before remediation Month(s) of highestTotal May @ 633 @ May April @673 Feb. Feb. 4871TM @ Aug. TM Aug. 3149 @ Jan. @9912 May @ 5433 @ May Feb. 4835 Feb. @ TM Too little Too data Too little Too data May @ 2015 TMMay @ 38%; Season (Mav - August) (Mav (Sept -April) (Sept. (Sept. - April) Low How Low High Flow HighFlow Flow Low (May-August) High Flow Flow High (Sept -April) Low Flow Low (May-August) (Sept. (Sept. -April) High Flow Flow High Low Flow Low Flow High - August) (May (May - August) (May (Sept. (Sept. - April) High Flow Flow High Stream Segment A68 M34 CC48 A72 A75Flow Low
XII- 00 (ch=chronic; TVS TVS (ac)= 103 TVS (ch)= 202 TVS (ac) « 201 TVS for same monthandlocation ac=acute) TVS (ch) = 185 TVS (ac) = 184 TVS (ch) = 104 TVS (ac) = 103 Ambient Ambient TVS (ac) = 270 TVS (ch)=s211 TVS (ac) = 108 TVS (ac)=210 TVS (ch)= 87 TVS (ac)* 86 TVS (ac)= 124 TVS (ch) = 125 [Dissolved Conc. [Dissolved Conc. 100%; [758] 100%; 92%; [644] TVS (ch) = 104 94%; [979] Peak month% dissolved; Attained] 99%; [205] 97%; [834] Potentially 100%; [376] TVS (ch) = 109 94%; [629] TVS (ch) = 271 Cannotpredict Cannotpredict Cannotpredict (Total conc. vahies) March @ March 1042 concentrationvalueand afterremediation April @207 May 700 @ May Month(s) ofMax May @ @ May 169 96%; [162] April 860 @ Aug. Aug. @758 Cannot predctCannot March @669 @ May 376 Cannot predictCannot Cannot predictCannot Fcurrent dissolved Fcurrent 94%; 94%; [1020]- Concentration] 99%; - [486] 99%; 92%; 92%; [653]- TM TM Peak month % Peak% month dissolved; TM 96%; 96%; [211] - TM 96%; [932] 96%; 100%; [256 ug/l] [256 100%; 97%; 97%; [1032] 100%; [156 ugA] ugA] [156 100%; 94%; 94%; [771] - TM TM 100%; [200 ng/I] [200 100%; TM TM (Total conc. values') Total valueConcentration May 710 @ March@1085 Month(s) of highest beforeremediation March491 @ May@220 April @1064 May @971 June @ 156 March@820 May @434 - [434] 100%; Feb. @256 yearly Season (May - August) (May (Sept - April) Low Flow Flow Low Low Flow Low (Sept April)- (Sept -April) High Flow HighFlow (May-August) HighHow Flow Low HighRow - (May August) (Sept - April) (May-August) Low Flow Flow Low (Sept April)- (May - (May August) High Flow HighFlow Flow Low High Flow High Flow Yearly 5 (only samplesavail) Segment A68 M34 CC48 A72 A75 3c Arrastra I I Stream
XII- vo It is unknown how much pH will change with remediation, but any changes are likely to be minimal. Iron is a major driver of pH, and iron reductions under the remediation scenario are projected to be small. Therefore, minimum pH standards are proposed to be set equal to current, seasonal pH values, except when those values are greater than 6.5. In those cases, TVS would apply. Table 12.2 shows the proposed pH standards.
Table 12.2 Segment Season pH Standard to Apply 2 6.5 TVS 3a Apr-Oct 6.4 6.4 Nov-Mar 6.1 6.1 3b Year NA NA 3c Year 7.4 TVS 4a Apr-Oct 6.1 6.1 Nov-Mar 5.5 5.5 4b Year 7.5 TVS 7 Year 3.8 3.8 8 Year 4.3 4.3 9b Apr-Oct 6.1 6.1 Nov-Mar 4.8 4.8
Model Results versus 85th Percentile
The Colorado Water Quality Control Division uses the 85th percentile method in determining ambient water quality. Essentially, 15% of all data is greater than and 85% of all data is less than the value used as the determinant value for ambient water quality. Thus, some high peak concentrations may not be noted or taken into account. While this method may be appropriate where minor amount of data exist, it provides little understanding of the changes in water quality over the seasons.
The model used in the UAA and used for developing the recommended standards gives a much clearer understanding of the seasonality of water quality. It allows standards to be set seasonally which can be more protective than setting one single standard that must accommodate attainable water quality concentrations during the season when they peak. In addition, the 85th percentile method could only be applied to the last three years of data because actions taken by Sunnyside Gold have changed water quality. The model was adjusted to factor in these changes. Thus, the model is based on eight years of water quality data which is more representative of year to year changes in the hydrological cycle.
A comparison of the 85th percentile values and the peak modeled values, which are used for recommending standards during low-flow time periods, shows that in many cases the values are very similar for segments 3a, 4a, and 9b. Revised Revised 3/5/01 Table 12.3 Comparison of Peak Modeled Values to 85th Percentile Values (All concentrations are dissolved except iron which is total recoverable. Units - ug/L) A68 (3a) | A72 (4a) | M3 4 (9b) Metal Model 85th Model 85th Model 85th A1 232 115 665 554 2536 2097 Cd 2.7 3.0 2.4 2.0 1.4 1.6 Cu 11 9 16 20 45 49 Fe* 673 227 5007 3701 4949 4233 Mn 2589 2500 1402 1600 545 471 Zn 1115 900 836 723 497 482 * 50 percentile values
CHANGES IN USE CLASSIFICATIONS
It is recommended that the new proposed segment 3c is classified for cold water aquatic life class 2 and recreation class 1. No fish have been found in Arrastra Gulch and zinc, cadmium, and copper exceed TVS during portions of the year. The sources of these metals may be considered irreversible.
It is recommended that the goal of cold water aquatic life class 1 be removed from segment 4a, and the use classification of aquatic life class 2 be retained. A few brook trout have been found near the bottom of the segment. As remediation takes place, more brook trout are expected to be found, but water quality will not support a thriving fishery nor a diverse population of other aquatic organisms.
Under the remediation scenarios, dissolved aluminum and total recoverable iron will continue to exceed TVS and chronic Biological Thresholds for all trout. Zinc concentrations will continue to preclude all trout except brook. Copper concentrations will exceed chronic Biological Thresholds for brook trout.
It is recommended that the cold water aquatic life class 1 use classification be removed from segment 9b, and the use classification of aquatic life class 2 be instituted. There is ample evidence that water quality will not achieve TVS in a twenty year time given any remediation scenario. Identified mining sources contribute very little aluminum to Mineral Creek. Even if one hundred percent of these sources were removed, dissolved aluminum would still reach dissolved concentrations three times higher than the acute TVS and Biological Thresholds for all trout. In addition, under the remediation scenarios, total recoverable iron will continue to be twice TVS and Biological Thresholds for all trout. Currently, no trout have been found in this reach during recent surveys and minimal macroinvertebrates have been found. After completion of all proposed remediation, the macroinvertebrate community diversity and density would remain minimal.
Table 12.4 lists the proposed changes in the format used by WQCC for segmentation, use classifications and standards. A N D I QUALIFIERS I TEMPORARY MODIFICATIONS 3 years beginning6/30/01: existinga m b ie n t q um a e ta lity ls. fo r a ll | ■ (rrfil ■ R/1ÎTT7- 3yoarc begtnmng | Ciiirh l= in until fi/3fWT7 foc-3 u^6/im ?(Ch)g5^o Temp mod effective, . Tamo mod affective Mn/cht=75n0 Temp mod effective A l/rh te 7 4r.uirtrt=15 n F«/rhte49fttZnic±i/ac\=?80 U *G 0 !]l n u frh )= 1 0 Se{ai)=10(Trec) Se(ac/ch)=TVSNi(acfch)=7VS A g (ac)= T V S Ag(ch)=TVS(tr)Zn(a^ch)=TVS A g (a c )*T V S Ag{ch)=TVS(tr) fc W rh i= T V R 7niac/ch>=650 F * ic M « 1 « in A I(ch )= T V S Cirfeh^TVS Cu(ac/eb)=TVS Pb(acfch)=TVSMn(Ch)~1000 Hg(ch)=0.01 (tot) Fe(ch)=300(dis) Pb(ac/ch)=TVS Hg(ch)=0.01(tcit)Ni(ac/ch)=TVS Se(acfch)=TVS Ag(ac)=TVS Fe(ch)*1000(Trec) Mn(eh)=50(dis) Fe=132(dis)Pb(ac/ch)=TVS M n /a rt= T V S Hg(ch)=0.01(tol) i*rff*vt74nn 7 rWac/ch>=980 uon 30 Znidii=3B0 METALS *V = S i V i manganese, and zrncthat is directed toward m aintainingand achieving waterand 4b quality and 9b.standards established fo r segments 3a, 4a, manganese,achieving and zinc water that4b—ôAd-Ôfe is quality directed standards toward maintainingestablished andfor segments 3a? 4a a rt A g jo h )-T V S Cd(ac)=TVS(tr)C d (ch)= T V S Crlll(ac)=50(Trec)CrVKac/ch)=TVSCu(ac/ch)=TVS Effective m til JineExisting 30,2001: ambient quality for aEffective ll metals asas ofof FebruaryJune 30,2001: 14,1995. AI(acAii)=TVS (Vtfnr.WTVR Crill(ac/ch)=TVSCrVI(ac/ch)=TVSC u (ac)= T V S As{ac)=50(Trec) The ajucuntialien of dissolved alum inim , cadmium.As(ac)=100(TiBc) copper, iron, lead, Effective until JuneExisting 30,2001 ambient: qualityEffective for a Theas ll metals ofconcentration June as 30,2001: of February of dissolved 14,1995. aluminum, cacfrniun,AsiactrSOnVfttf copper, iron, Cd/rh*=14lead, r.rllUartSIVTmri CrWac/ch)=TVS Cuichl=6CufacWTVS Phfac/ch\=TVR Fe/rti>=inn(VTrer.1 Mniac/ch)=TVS Hninhtf) NifeRMteTVS 01«nh Apfarrt=7VS Aofrfi^TVRitrl Zniac/ciri=200 F^r+i\=4onn CuTcM-fl Cuinhfc=fl Al(acfeh)=TVSAs(ch)=100(Trec) Cd(cWac)=TVS Cr11l(ac/cti)=TVSCrVI{ac/ch)=TVS ftn n t 1 Alffiii=7?0 to A o r 3 0 7 S = 0 .0 0 2 N 0 2 = 0 .0 5 N 0 j= 1 0 C l= 2 5 0 B = 0 .7 5 S 0 4 = 2 5 0 S = 0 .0 0 2 B = 0 .7 5 S = 0 .0 0 2 B = 0 .7 5 INORGANIC * ' m a/l NHs(ac)=7VS NHj(ch)=0.02Cb(ac)s0.019Cb(ch}=0.011C N = 0.005 NHs(ac)=TVS NH*(ch)=0.Q2 Cyac)=0.019Cych)*0.011CN=0.QD5 NH»facl=TVS 8*0 007 nN =Q 0 P 5 NHs(ac)=TVS NHj{ch)=0.02Cyac)=0.019 C N =0.005 Cych)=0.011 and 6 .0 -9 .0 PHYSICAL - BIOLOGICAL D O . = 6 .0D.O. m (sp)=7.0 g /l mg/! F.Coli=200/100ml pH = 6.5-9.0 pH = 5.8-9.0F.Coli=200/100ml D.O. = 6.0D mg/I .O . (s p )= 7 .0 m g fl F.Coli*20QM00ml Mav 1 A— in 31' nH = 6 0 -9 0 D .0 .(s p )= 7 .0 mg/1 F.Col(=2000/100ml p K = fi4 - a n SeDM-Aw. 30; D .O . = 6 .0 mg/1 F.Coli=200/100ml Mav 1 Ann— o 31- H = 6 1 -9 0 nH=fi 5-9 0 Classifications NUMERIC STANDARDS Aq Life ColdRecreation 1 W 1 ater Supply RecreationAgriculture 2 R e c re a tio n 2 Agriculture Aq Life Cold 1 Agriculture Ac Life Cold 2 Recreation 1 Recreation 2 pH Aq Life Cold 2 UP UP UP UP 3/2JQ1' D e sia F ffu n ti* Revised 3/5/01 including a ll wetlands, lakes and reservoirs, which are within the W eminuche Wilderness Area. and wetlands,immediately from theaxeeot above outletfor the ofsoedfic Denver confluence listinasLake w ith to a Maggiein point SnamonM Gulch, Reament fi point immediatatyGulch to below immediatelyC reek. the confluence above the with confluence Maggie with Cement point immediatelyCreek to aboveaMineral point the immediatelyCreek. confluence w above ith Cementthe confluence with point immediatelyC re e k to th above e c o the n flu confluence e n c e w ith E with lk C re Mineral e k. R E G IO N : 9 BASIN: ANIMASStream AND FLORIDA Segment RIVERDescription 1. M l tributaries tothe Animas River and Florida River, 2. Mainstam ofthe Animas River, including all tributaries 3a. Mainstem of the Animas River, inducting wetlands, from a V . Arrastrs Gulch includina all lakes tributaries, and 3b. Mainstem ofthe Animas River, nduding wetlands, from a 4a. Mainstem ofthe Animas River, including wetlands, from a
XTT- 12 AND QUALIFIERS TEMPORARY MODIFICATIONS until 6/1/04 fer3voare 7 r ií d iC j» years beginning ambient qualitym e ta ls.for all years beginning6/30/01: existingambient qualitym e ta ls for a ll S/30/01: existing T em p M o d e ffe c tiv e T e m p m od e ffe c tiv e f o r 3 T e m p m od e ffe c tiv e f o r 3 Ni(ac/ch)=TVS Se(ch)=10(Trec)A g (ac)= T V S Ag(ch)=TVS(tr) Zn(ac/ch)=TVS Se(ac/ch)=TVS A g (a c)= T V S Ag(ch)=TVS(tr)2n(ac/ch)=TVS Zn(ac/ch)=TVS; 2004- June 30,2064- Ag{ch)=TVS(tr) E ffe c tiv e a s o f Se(ac/ch)=TVSA g (a c)= T V S Ag(ch)=TVS(tr)Zn(ac/ch)=TVS 3 0 3 0 0 4 2 0 0 4 : 7tVac/ch'=256 Mn(ch)=50(dis)Hg(ch)=0.01(tot)N i(ch )= T V S Fe(ch)=300(dis)Fe(ch)=1OOOfTrec) Pb(ae/ch)=TVSMn(ch)=50(dis)Hg(ch)*0.01(tot)N itc h )= T V S Fe(eh)=300(dis)Fe(ch)=1000CTrec)Pb(ae/ch)=TVSMn(ch)=50(dis)Hg(ch)=0.01(tot) Effective until June Fe(ch)=300(dis)Fe(ch)=1000(Trec)Pb(ac/ch)=TVS u a fl METALS 9b. ______rranm ese, and zincthat is directed toward maintaining and achieving Crlll(ac/ch)=TVS manganese, waterand zinc quality that standards is directed established toward maintainingfo r segments and 3ar achieving4a, ancMbrand «uatar aualitvstandards established form u iimuls 3a. 4a 4b, and 9b. CiVl(ac/ch)=TVS E ffe c tiv e a s o f J u n e 3 0 ,2 0 0 1: C d (ch)=T V S CrVt(ac/ch)=TVS k*-i/su-/i-hte7VS Cd(ac)=TVS(tr)C d (ch)= T V S CrIII(ac)=50(Trec) Cu(ac/ch)=TVS Existing ambient qualityE ffe for c tiv all e a smetals o fJ u n as e 3 0of ,2 February 0 0 1 : 14,1995. Effective until JuneExisting 30,2001 ambient : qualityfor a ll metals as of February 14,1995. A s(ch )= 5 0 Cu(ac/ch)=TVSCd(ac)=TVS(tr) Effective until June 30,2001: The concentration of dissolved aluminum, cadmium, copper, iron, lead, The concentration of dissolved aluminum, cadmium, copper, iron, lead, Cd(ac>=TVS(tr) C d (ch)=T V S Cr1ll(ac)=50(Trec)CiVI(adcti)=TVSCu(actah>=TVS Cd(ac)=7VS(tr)C d (ch)= T V S Cr1ll(ac)=50(Trec)CrVI(ac/ch)=TVSCu(ac/eh)*TVS A s (c h )= 5 0 A s(cJi)= 50 As(ac)=50(Trec) N 02N = 0 .0 5 N C h=10 C N 2 5 0 S 0 4 = 2 5 0 S = 0.0 02 B = 0 7 5 02N = 0 .0 5 N 0 s= 1 0 C l= 2 5 0 S 0 4 = 2 5 0 S = 0 .0 0 2 B = 0 .7 5 N 0 2 = 0 .0 5 C N 250 S 0 4 = 2 5 0 S = 0.0 02 02N = 0 .0 5 NO^IO C l= 2 5 0 S 0 4 = 2 5 0 S = 0 .0 0 2 B = 0 .7 5 N 0 a = 1 0 B = 0 .7 5 INORGANIC m afl N H afacK T V S NHs(ch)=0.02 Cl2(ac)=0.019 Cl2(ch)=0.011 C N = 0.005 NHj(ac)=TVSNHa(ch)=0.Q2 Cli(ac)=0.019Cl2(tfi)=€.011 C N0.005 = Cych)=0.011C N = 0.005 NHsfac^TVS NHj(ch}=0.02Ch(ac)=0.019 Ch(chJ=0-011 C N = 0.005 NHs(ac)=TVS NHj(ch)=Q.02 CyacKl.019 a n d PHYSICAL BIOLOGICAL F.Coli=200/100ml F.Coli=200/100ml p H = 4 .5 -F.Crii=200/100mi 9 .0 D.O. =6.0D.O. mg/l (sp)=7.0pH =mgfl 6.5-9.0 pH = 3.7-9.0 D.O. = 6.0 mg/l F.Col¡=20Q/100ml D.O. = 6.0 mg/i F.Coli=200/100ml D.0.(sp)=7.0pH = mg/l6.5-9.0 D.O. =6.0mD.O. gfl (sp)=7.0mg/l pH = 6.5-9.0 F.Colr=200/100mJ D.O. (sp)=7.Qp H mg/l = 6 .5 -9 .0 NUMERIC STANDARDS R e c re a tioAgriculture n 2 RecreationAgriculture 2 Recreation 1 R e c re a tio nW 2 a te r S uAgriculture p p ly Classifications Aq Life Cold 1 W a te r S uAgriculture p p ly Aq Life Cold 1 RecreationW 1 ater SupplyAgriculture Aq Life ColdRecreation 1 W 1 ater SupplyAgriculture Aq Life Cold 1 UP UP D e s ia PeawriBGulch i b o u n d a ry. Baker’s Brickieto the Southern Ute Indian Reservation the confluence w ith Elk Creekto Baker's Bridge, the South Mineral Creek. from the sotrce to a point immediately above the confluence with lakes, andAnimas reservoirs, Rrver. from the source to the confluence with the Southern UteM eIndian x ic o bo rdReservation e r. boindary to the Colorado/New 8. Mainstem of Mineral Creek, 7. Mainstem of Cement Creek, including a ll tributaries, wetlands, 5a. Mainstem ofthe Animas River, including wetlandsjrom Stream Segment Description R E G IO N : 9 BASIN: ANIMAS ANO FLORIDA RIVER 5b. Mainstem ofthe Animas River, including wetlands, from the 4b. Mainstem ofthe Animas River, including wetlands, from “ SEE STATEMENT OF BASIS AMD PURPOSE X II-13 CrVl(ac/ch)=TVS Hg(ch)=0.01{tot) 9 b . Matnstem erf Mineral Creak, including wetlands, from immediately D.O. = 6.0 mg/l NHa(ac)=TVS S = 0.0 02 As(ch)=100(Trec) C u (a c)= T V S Ni(ac/ch)=TVS above the confluence w ith the South Fork to the confluence with D.O. (sp)=7.0 mg/l NHj(di)=0.02 B = 0.7 5 Se(ac/ch)=TVS Tanin mod affarth/a until pH r 6.5 - 9.0 Cb(ac(=0.019 NOTOOS Pb(ac/ch)=TVS the Animas River. UP B/1/07- F.Coli=200/100ml Cb(ch)=0.011 Ag(ac)=TVS(tr) Alfehte2SOO C N = 0.005 Crll1(ac/ch)=TVS Mn/ar/nh^TVS r.irfrt'to lfi R ant 1 to A p t 3Q-. Fft/rtrt=4900 A1/arJrhte74rm nufRhtelO Fefcti\=1900 a_3Q0l^7nfar./eht=210 Znfac/chW17Q M ay G d (n h )-1 .7 C u (c h )-5 7 Fo(ch)~551S(Trec) 2p^44 C d (ch )-T V 8 C u (c h )-T V S Fe(ch)~1000(Tree)
TEMPORARY R E G IO N : 9 MODIFICATIONS AND OACINi ANHW6 AMD FLORIDA niVCR INORGANIC METALS QUALIFIERS Stream Segment Description PHYSICAL and BIOLOGICAL mo/1 upn S = 0.0 02 As(ac)=50(Trec) Fe(ch)=300(dis) Ni(ec/ch)=TVS 10. Mainstem of the Florida River from the boundary of the Aq Life Cold 1 D.0.=6.0 mg/l NH3(3C)=TV$ B = 0.7 5 Cd(ac)=TVS(tr) Fe(ch)=1 OOOfTrec) Se(ch)=10CTrec) W efrinuche W ilderness Area to the Florida Farmers Canal Recreation 1 D.0.= 7.0mg/I NHs(ch)=0.02 N 0 j= 0 .0 5 C d (ch)= T V S Pb(ac/di)=TVS A g (a c)= T V S Headgate, accept for the specific listings in Segment 12s. W ater Supply pH = 6.5-9.0 Cyac)=0.019 Mn(eh)=50(dis) Ag(ch}=TVS(tr) Agriculture F.Coli=200/100ml cycti)=o.oii N 0 j= 1 0 Crlll(ac)=50(Trec) C N =0.005 C 1=250 CrVI(ac/ch)=TVS Mn(ch>=1000(Trec) Zrt(ac/ch)=TVS S 0 4 = 2 5 0 Cuiac/cuKTVS Hof *>«0.01 (tott S -0 .0 0 2 As(ac)=50fTrec) Fe(ch)=300(dis) Ni(ac/ch)=TVS 11. Mainstem of the Florida River from the Florida Farmers Aq Life Cold 1 D.O. = 6.0 mgfl NI-fe(ac)=TVS Cd(ac)=TVS(tr) Fe(di)=1000(Trec) Se(ch)=10(Trec) Canal Headgate to the confluence with the Animas River. Recreation 1 D.0.(sp)=7.0 mg/l NHs(Ch)=0.CI2 B = 0.7 5 Pb(ac/ch)=TVS Ag(ac)=TVS W a te r S u p p ly pH=6.5-9.0 Cyac)=0.019 N 02 = 0 .0 5 C d (ch)= T V S Mn(ch)=50(drs) Ag(ch)=TVS(tr) Agriculture F.Coli=200/100ml Cydi)=0.011 N 03= 10 Crlll(ac)=50(Trec) C N =0.005 C l= 2 5 0 CrVI(ac/ch)=TVS Mn(diJ*1000fTrec) Zn( ac/oh )=TVS S 0 4 = 2 5 0 Cutec/chKTVS Hoich >=0.01 ito t)
lililí As(ac)=50(Trec) Fe(ch)=300(dis) Ni(ac/ch)=TVS 12a. A ll tributaries to the Animas River, ¡Deluding all lakes and Aq Life Cold 1 DO. =6.0 mg/l N H ^a c K T V S NHa(ch)=0.02 Cd(ac)=TVS(tr) Fe(ch)=1000CTree) Se(ch)=10fTrec) reservoirs from a point immediately above the confluence Recreation 1 D.O. (sp)=7.0 mg/l C d(eh)=T V S Pb(acfch)=TVS A g (a c)= T V S with Elk Cr. to a point immediately below the confluence W a te r S u pply pH = 6.5-9.0 Cb(ac)=0.019 Crlll(ac)=50(Trec) Mn(ch)=50(dis) Ag(ch)=TVS(tr) with Hermosa Cr. except for specific listings in Segment Apiculture : F.Col i=200/100ml CWdi)=0.011 CrVI(ac/ch)=TVS Mn(ch)=1000(Trec) Zn(ac/ch)=TVS 15. AH tributaries to the Florida River including a ll lakes C N =0.005 Cu(ac/ch>=TVS H g (ch )= 0 .0 1 (to t) and reservoirs from the source to the outlet of Lemon Reservoir except the specific listing in Segment 1. Mamstems of Red and Shearer Creeks from their sources
Fe(ch)=300(dis) Ni(ac/ch)=TVS Aq Life Cold 1 D .O . = 6 .0 m g /l NHs(ac)=TVS S = 0.0 02 As(ac)=50(Trec) 12b. Lemon Reservoir. Fe{ch)=1000(TrBC) Se(ch)=10(Trec) Recreation 1 D.O. (sp)=7.0 mgfl NH»(ch)=0.02 B = 0.7 5 Cd(ac)=TVS(tr) Pb(ac/ch)=TVS A g (a c)= T V S W a te r S u p p ly pH = 6.5-9.0 Cyac)=0.019 N 0 2= 0.05 C d (ch)=T V S Mn(ch)=50(dis) Ag(ch)=TVS(tr) Agricultife F.Coli=200/100ml Cych)=0.011 N 0 3= 10.02 Crlll(ac)=50fTrec) C N =0.005 C l*2 5 0 CrVKac/ch)=TVS Mn(ch)=1000(Trec) Zn(ac/ch)=TVS S 0 4 = 2 5 0 Cu(ac/di)=TVS Ho(ch)=0.01ftot) NHj(ec)=TVS S = 0.0 02 As(di)=50(Trec) Fe(ch)=1000(Trec) A g (a c)= T V S 13a. Mainstem of Junction Creek, and including ail tributaries, A q L ife C o ld 2 D.O.=6.0 mg/l NHs(ch)=0.02 8 = 0 .7 5 Cd(ac)=TVS(tr) Pb(ac/ch)=TVS Ag(ch)=TVS(tr) from U.S. Forest Boundary to confluence with Animas UP R e c re a tio n 2 D.0.(sp>=7.0mgfl CWac)=0.019 N 02 = 0 .0 5 C d (ch)= T V S Mn(ch)=1000(Trec) Zn(ac/ch)=TVS R ive r. A p ic u ltu re pH = 6.5-9.0 F.Col ¡*2000/100ml C«(*)=0.D11 Crlll(ac/ch)=TVS H g (ch )= 0 .0 1 (to t) C N =0.005 CrVI(ac/ch)=TVS Ni(ac/ch)=TVS r.uiac/ch\=TVS SeiacfchKTVS
13b A ll tributaries to the Animas River, including an lakes and Aq Life Cold 2 D.O j 6.0 mg/l reservoirs, front a point immediately below the confluence UP R e c rs a tn n 2 D.0.(sp)=7.0 mg/l with Hermosa Creek to the Southern Ute Indian Agriculture pH = 6.5-9.0 Reservation boundary except for the specific listings rn F.C o If 2 0 0 0 /1 0 0 it iI m , 11,12a, 13b; 13a and 14; all tributaries to the Florida River, including a ll lakes and reservoirs, from the outlet of Lemon Reservoir to the confluence w ith the Animas River, except for specific listings in Segment 12a. AND QUALIFIERS TEMPORARY MODFICATIONS unless otherwise noted. A ll m e ta ls a re T re e Hg(cft)=2{tot)S e (ch )= 1 0 A g (ch )= 5 0 Zn{ch)=5000 Ni(ac/ch)*TVSSe(ch)=10(Trec) A g (a c)= T VAg(cfi)=7VS{tr) S Zn(ac/ch)=TVS Cu(ch)=1000Fe(ch)=0.3(dis)P b (ch )= 5 0 M n (ch )= 5 0 Fe{ch)=1000(Trec)Pb(ac/ch)=TVS MN(ch)=50(drs) Mn(ch)=1000(Trec) H g (ch )= 0 .0 1 (to t) Fe(ch)=300(dis) u g fl METALS C d (ch )= 1 0 Crltl(ch)=50CrVI(ch)=50 Crlil(ac)=50(Trec)CrVI(ac/ch)=TVSCu(ac/ch)=TVS A s(c h )= 5 0 Cd(ac)»TVS(tr)C d (ch )= T V S As(ac)=50(Trec) S 0 4 = 2 5 0 N 0 3= 10 C1=250 S 0 4 = 2 5 0 B = 0.7 5 N 0 2 = 0 .0 5 N 0 j= 1 0 C l= 2 5 0 S = 0 .0 0 2 INORGANIC m g /l C N = 0.2 S = 0 .0 5 N 0 2 = 1 .0 N Ha(chN )=0.02 Cyac)=0.019Clî(ch)=0.011 C N = 0 .0 0 5 NHj(ac)=TVS and PHYSICAL BIOLOGICAL D.0.(sp)=7.0pH = mg/l 6.5-9.D F.Coli=2000/100ml F.Coli=200/100ml D.O.= B.Omg/l D.O. =6.0D.O. mg/l (sp)=7.0 pH =mg/l B .5 -9 .0 D.0.(sp)=7.0 mg/l F.Coli=2000/100ml D -O ..E 6 .0 m g/l pH = B.5-9.0 NUMERIC STANDARDS R e c re a tio n 2 A q L ife C o ld 2 W ater SupplyAgriculture Recreation W 1 ater SupplyAgriculture Aq Life Cold 1 RecreationAgriculture 2 A q L ife C o ld 2 Classifications UP UP Bouldino Gouldina Creek from the source to Elbert Creek, and Nary Draw from the source to Naviland Haviland Lake. Animas River. 12b, 13a andand 14;reservoirs, all tributaries from the to outlet the Florida of Lemon River, Reservoir including to the a confluence ll lakes with Mexico border, exceptfor thethe specific Animas listings River, except in Segments for specific 1 0 ,1 listings 1 ,12a, in Segment 12a. the Southern Ute Indian Reservation boundary to the Colorado/New 15. Mainstem of Purgatory Creekfrom source to Cascade, Cascade Creek, 14. Mainstem of Lightner Creek from the source to the confluence with the 13c. All tributaries to the Animas River, including all lakes and reservoirs, from Stream Segment Description BASIN: ANIMAS AND FLORIDA RIVER X II-15 While the recommendations above are directed at WQCC, there are other measures that different government entities could implement besides mine site remediation that should improve water. For example, a substantial amount of metal loading is attributed to surface runoff from quartz-sericite-pyrite and acid sulfate areas. Only a small proportion of loading has been identified as runoff from mine waste sites. Certain best management practices could be implemented by federal land managers and San Juan County to minimize metal loading. These practices would be most effective if initiated in quartz- sericite-pyrite and acid sulfate areas (See map, Chapter VII, Figure 7.1.). They include:
♦ reducing or eliminating grazing which reduces ground cover and thereby accelerates erosion and exposure of oxygen and water to metal sulfide bearing substrates . (Some draining adits, especially in Cement Creek, cany metal concentrations toxic to grazing animals),
♦ maintaining water bars on county roads, especially when they are first opened in spring,
♦ implementing erosion control and revegetation measures on public,
♦ restricting road development in mineralized areas, especially where highly mineralized areas could be are exposed,
♦ implementing county-wide erosion control and construction revegetation standards.
Other recommendation include:
♦ Ensuring that remediation of sites has minimal impact on historic values by working closely with the San Juan Historical Society and San Juan County,
♦ Monitoring of silver concentrations that may be increase because of recently re introduced upwind cloud seeding operations, USE ATTAINABILITY ANALYSIS (UAA) TABLE OF CONTENTS
Contents of the UAA are bound in several folders. Water quality data and some worksheets are provided only on CD-ROM #1. In addition, the entire UAA is available on CD-ROM #2.
I. UAA TEXT AS SEPERATELY BOUND FOLDERS INCLUDES THE FOLLOWING:
PREFACE
CHAPTER I - INTRODUCTION Appendix 1A - EPA Letter of Disapproval of Standards
CHAPTER II - PROTECTING EXISTING AND POTENTIAL USES
CHAPTER m - ADDRESSING WATER QUALITY
CHAPTER IV - AREA OVERVIEW
CHAPTER V - EXISTING USES
CHAPTER VI - BIOLOGICAL & PHYSICAL ANALYSES Appendices in Separate Folder
CHAPTER VII - METAL LOADING PROCESSES Appendices in Separate Folder
CHAPTER VIII - EXISTING WATER QUALITY AND SOURCES OF DEGRADATION Appendix 8C - Description of water quality regression method (WQRM). (8A & 8B on CD-ROM only)
CHAPTER IX - BIOLOGICAL POTENTIAL AND LIMITING FACTORS ANALYSES FOR IMPAIRED STREAM SEGMENTS
CHAPTER X - REMEDIATION Appendices in separate folders; Appendix 10E on CD-ROM only
CHAPTER XI - REMEDIATION SCENARIOS Appendix 11A on CD-ROM only
CHAPTER XII - RECOMMENDATIONS II. UAA APPENDICES AS SEPARATELY BOUND FOLDERS
APPENDICES 6A- 6R 6C Appendix 6A - Fisheries Report Appendix 6B - Macroinvertebrate Report Appendix 6C - Toxicity Report
APPENDICES 7A- 7B 1C. Appendix 7A - Geology Appendix 7B - History Appendix 7C - Mining History
APPENDIX 10A - Mineral Creek Remediation Feasibility
APPENDIX 10B - Cement Creek Remediation Feasibility
APPENDIX IOC - Upper Animas Remediation Feasibility (Above Eureka)
APPENDIX 10D - Upper Animas Remediation Feasibility (Below Eureka)
III. CD-ROM #1 INCLUDES THE FOLLOWING UAA DATA AND WORKSHEETS- APPENDIX 8A - ARSG Water Quality Data Mineral Creek Cement Creek Upper Animas Lower Animas
APPENDIX 8B - Analyses of Water Quality Data and Modeled Data
APPENDIX 8C - Description of water quality regression method (WQRM)
APPENDIX 10E - Adit and Mine Waste Rank and Prioritization Tables
APPENDIX 11A -Combined Adit Load and Cost Calculations -Combined Mine Waste Load and Cost Calculations
IV. CD-ROM #2 INCLUDES ALL COMPONENTS OF THE UAA ABBREVIATIONS AND ACROYNMS
TRACE METALS Ag Silver Al Aluminum As Arsenic Cd Cadmium Cu Copper Cr Chromium Hg Mercury Ni Nickel Pb Lead Fe Iron Mn Manganese Sb Antimony Th Thallium Vn Vanadium Zn Zinc
MAJOR CATIONS Ca Calcium K Potassium Mg Magnesium Na Sodium SiO Silica
MAJOR ANIONS C03 Carbonate HC03 Bicarbonate NH3 Ammonia S04 Sulfate DO Dissolved oxygen pH Measure of acidity/basicity
UNITS OF MEASURE cfs Cubic feet per second (28.321/s) 1/s Liters per second mg/1 Milligrams per liter (ppm) ug/1 Micrograms per liter (ppb) ORGANIZATION AND AGENCY ACRONYMS
ARSG Animas River Stakeholder Group BLM U S Bureau of Land Management BWG Biology Work Group (ARSG) CDOW Colorado Division of Wildlife CDPHE Colorado Department Public Health and Environment EPA U S Environmental Protection Agency DMG Colorado Division of Minerals and Geology SGC Sunnyside Gold Corporation USFS U S Forest Service USGS U S Geological Survey WQCC Colorado Water Quality Control Commission WQCD Colorado Water Quality Control Division
OTHER AT American Tunnel CPDES Colorado Pollution Discharge Elimination System BDL Below limit of detection TVS Table value standard s s Stream standard UAA Use Attainability Analysis WQS Water quality standard WQRM Water quality regression method PREFACE - ANIMAS RIVER UAA
This Use Attainability Analysis (UAA) is designed to fulfill requirements of the Clean Water Act for certain sections of Animas River Basin in southwest Colorado. A UAA is a scientific analysis that describes what ‘\ises” are attainable and what water quality standards are needed to protect those uses through certain segments of a river and its tributaries. The results of the analysis form recommendations to be submitted to the Colorado Water Quality Control Commission (WQCC) which will then promulgate use classifications, water quality standards, and segment descriptions after considering the UAA and other evidence at a rulemaking hearing.
Most UAA’s are put together by government entities or corporations. The Animas River UAA is unique because it is the result of a wide range of efforts from numerous stakeholders - citizen groups, mining corporations, local, state, and federal government agencies, and private citizens. This ad hoc group, called the Animas River Stakeholders Group (ARSG), has no formal structure, yet it has been able to develop a fairly sophisticated analysis of metal loading and associated problems in the historical mining areas surrounding Silverton, Colorado. This area, known as the Upper Animas Basin, influences water quality in the Animas River mainstem all the way to its confluence with the San Juan River.
Because of the diversity of interests and concerns regarding water quality in the Animas River Basin, this UAA has a broad audience who may not be very familiar with Colorado’s water quality programs. The initial chapters of the UAA are designed for this readership.
The first chapter discusses what a UAA is and why it is required. It also describes current use classifications and standards in the Upper Animas Basin and provides some historical background for how they were determined. The second chapter summarizes the programs used to protect water quality under the Clean Water Act, how they apply to inactive and abandoned mine sites, and what types of liabilities land owners may have with regard to these sites. Chapter III summarizes all the work that has been done over the last eight years to characterize water quality problems in the Upper Animas Basin and what work has been done to improve water quality. The fourth chapter gives an overview of the physical, ecological, historical, cultural and economic aspects of the Upper Animas Basin.
The actual UAA analysis begins with Chapter V which identifies what classified uses are physically occurring. These uses may include different levels of health of aquatic life, different forms of recreation, water supply, and agriculture. Uses that are already occurring must be protected.
The classified use of most concern is “aquatic life.” Chapter VT summarizes the current biological condition of the Animas River. The summary is based upon three very detailed reports (included in the appendices) on fisheries, macroinvertebrates, and biotoxicity. The first two reports cover the length of the river and provide baseline data and methods of measurement that can be used to demonstrate the benefits of future mine site remediation to aquatic species. The biotoxicity profiles provide graphical and statistical information concerning exceedances of “biological thresholds” of three species of trout as well as exceedances of “Table Value Standards” (TVS) which the WQCC uses as a guide to set standards. Biological thresholds are the minimum metal concentrations that are toxic to particular species, in this case brook, brown and rainbow trout. Many of these biological thresholds are equivalent to Table Value Standards. Some are different. Using data from the last eleven years, the report contains a detailed analysis of the frequency with which those thresholds and Table Value Standards have been exceeded, the magnitude of those exceedances, and when and where they have occurred. This information is used in later chapters to determine factors that currently limit aquatic life and what levels of cleanup might be necessary to attain sustainable populations of target species.
Chapter VII discusses metal loading which is the main impairment to aquatic life. It describes where the metals come from and how they get into the water. Metal loading results from both natural and human-related activities. The chapter summarizes a number of studies that document historical and current metal loading from both natural and human-related sources.
Chapter VIII analyzes the impact of metal loading on stream segments in the Upper Animas Basin. There are three analyses. The first two compare current water quality with current water quality standards and with TVS. The initial comparison utilizes the 85 percentile method used by the Colorado Water Quality Control Division (WQCD). The other comparison considers the variation in water quality that occurs with different flow regimes over the annual cycle through use of a water quality regression model derived from eight years of data. The last analysis identifies the relative contributions from different sources - base flow (including mine adits and groundwater) and seasonal runoff (including runoff from mine waste) - through use of the regression model. This analysis focuses on the six metals that affect aquatic life in the Basin— aluminum, cadmium, copper, iron, manganese and zinc.
Chapters V through VIIl present the physical, biological, and chemical parameters that may affect aquatic life in the Animas River Basin. Chapter IX analyzes those factors to determine which ones are actually limiting aquatic life. This “limiting factors analysis” includes everything from temperature and pH to metal concentrations and physical habitat. In addition, the chapter estimates the biological potential of segments of the Upper Animas Basin if identified, mine- related sources of loading were non-existent.
Chapter X follows with an introduction on how limiting factors arising from mine and mill site contamination can be remediated. It includes remediation techniques and what some of the difficulties are. It also describes a characterization and prioritization process of 174 mine adits and 169 mine waste piles. Factors used in the evaluation include physical access, location with regard to impaired stream segments, specific metals involved, amount of metals leaving the site, the potential for remediation, cost of remediation, etc. Sites are ranked in relation to each other for specific metal contributions (adits) or potential contributions (mine waste piles).
Chapter XI provides scenarios describing potential metal reductions and costs if a number of characterized sites are remediated. The potential reduction of loading sources are incorporated into the water quality model described in Chapter VIII to predict the impact of the reductions on instream water quality. Several remediation scenarios with estimated costs are listed. Actual remediation of sites would depend on cooperation from property owners including federal land managers and available funding. The final chapter combines the remediation scenarios with the limiting factors analysis to estimate the feasibility and cost of attaining standards that should improve aquatic life. Using the four main components of the UAA - biological assessment, water chemistry assessment, limiting factors analysis, and remediation analysis - recommendations are made for segmentation, use classification, and water quality standards.
Clearly, the UAA recommendations are very important for setting use classifications and standards. However, by law, the Commission must review use classifications and standards every three years. Therefore, as new information becomes available, adjustments can be made.
ACKNOWLEDGEMENTS
While a team of three members of ARSG has been responsible for putting the UAA together, numerous other stakeholders have had extensive, direct involvement in a number of chapters. Without these efforts, mostly volunteer, the UAA would not have been possible. We need to acknowledge: Barb Horn (Colorado Division of Wildlife), Larry Perino (Sunnyside Gold Corporation), Steve Fearn (Silver Wing Mining Corp.), Bill Jones (Root & Norton Assayers), Sara Staber (River Network, Inc.), Paul Krabacker, Jim Herron, and Bruce Stover, (Colorado Division of Minerals and Geology), Ken Leib, (U.S. Geological Survey), Tom Strain, (U.S. Bureau of Reclamation), Chester Anderson (B.U.G.S. Consulting), and Dave Wegner (Ecosystems Management, lnc.),for their dedication and efforts.
We would also like to acknowledge a number of other stakeholders whose work was not done specifically for the UAA, but was invaluable for the analysis. They include: Win Wright, Paul von Guerard, Stan Church, Bryant Kimball, Kirk Vincent, John Besser (U.S. Geological Survey), Pat Davies (Colo, Division of Wildlife), Stephanie Odell, Rob Robinson, Barbara Hite, Loren Wickstrom (U.S. Bureau of Land Management), Dave Gerhardt, Cathleen Zillich, (U.S. Forest Service), Stan Powers (U.S. Bureau of Reclamation), Dan Beley, Robert Gallegos, and Greg Parsons, (Water Quality Control Division), Carol Russell (U.S. Environmental Protection Agency), Matt Sares (Colorado Geological Survey), and Gary Broetzman (Colorado Center for Environmental Management).
We would also like to thank those members of the local community who have not been included above, but who frequently volunteered their time to attend meetings, help with special events and add their local insights and perspectives. They include: Chris George (St Paul Lodge), Chris Smith (San Juan County Commissioner), Fred Clarke (Little Nation Mining), and Rich Perino (San Juan County Commissioner).
FUNDING ACKNOWLEDGEMENTS
Extensive monitoring and characterization of the watershed began in the late 1980's through a cooperative effort primarily funded by the Colorado Department of Health. Following the formation of the Animas River Stakeholders Group in 1994, funding has come from numerous local, State, and Federal agencies, private citizens, and mining companies. The crafting of this document was funded through contributions from the San Juan County Commissioners, City of Durango, Southwest Water Conservation District, Colorado Division of Minerals and Geology, Colorado Energy Impact Assistance Program, Bureau of Land Management, Bureau of Reclamation, and the Environmental Protection Agency. To these entities, and to the numerous participating individuals, companies, and agencies who have contributed in-kind services along the way, we owe our deepest gratitude. About the Authors:
A Colorado native, Peter Butler holds a Ph.D. in Natural Resource Policy from the University of Michigan (Ann Arbor). He has sixteen years of experience with Colorado water issues. He is a former commissioner on the Colorado Water Quality Control Commission and former director of Friends of the Animas River. Peter was a founding participant of the Animas River Stakeholders Group and has contributed countless hours of volunteer services to the group.
Bob Owen has an MS in Applied Statistics and Operations Research from the University of Northern Colorado and a BS in watershed management from Colorado State University. He worked in water quality programs for the state of Colorado from 1976 to 1997. From 1994 until 1997 he focused on the effects of mining and metals on the water quality of the upper Ammas Basin. He currently resides in Albuquerque, New Mexico.
William Simon has been a resident of Silverton since 1971. He has 30 years experience working in the natural resource restoration and mine reclamation fields. As a volunteer and San Juan County Commissioner, William began aquatic restoration activities within the Ammas basin in 1985. He has a degree in biology from the University of Colorado and completed the doctorate program at the University of California, Berkeley in evolutionary ecology. William has been the coordinator for the Animas River Stakeholders Group for the past 6 years. CHAPTER I - INTRODUCTION
This is an analysis of water quality issues pertaining to the upper part of the Animas River watershed. The Animas River begins high in the San Juan Mountains, above Silverton, in southwest Colorado. The river flows south through Durango for almost eighty miles to the New Mexico border. It continues nearly thirty more miles, meeting the San Juan River in Farmington, New Mexico.
Aquatic life in much of the Upper Animas River watershed, particularly Mineral and Cement Creeks, is limited or even non-existent. In areas where there is adequate flow, heavy metal loading is the main limiting factor curtailing aquatic species. Some metal loading is caused by natural processes, and some loading is the result of human activity. Other possible water quality problems have been investigated, but they are minor relative to the impacts of heavy metals. (See Chapter VIII.)
There is general agreement that the water quality in the Upper Animas River can be improved. How much improvement is possible or feasible is a difficult question which this Use Attainability Analysis (UAA) attempts to answer.
NEED FOR A USE ATTAINABILITY ANALYSIS
One of the goals of the federal Clean Water Act (CWA) is to provide, wherever attainable, "... water quality which provides for the protection and propagation of fish, shellfish, and wildlife and provides for recreation in and on the water .. ”(CWA, § 101). This is often referred to as the “fishable, swimmable standard.”
State legislation closely follows the federal act by requiring the same protection for fish and wildlife and by requiring protection for “beneficial uses” such as recreation, agriculture, water supply, etc (Colorado Water Quality Control Act, C.R.S. 25-8-102). The state’s Water Quality Control Commission (WQCC or simply Commission) and Water Quality Control Division (WQCD) in the Department of Public Health and Environment are required to implement provisions of the state legislation.
Under the state’s water quality protection program, use classifications are assigned to lakes, reservoirs and segments of rivers and streams. Use classifications protect existing or potential uses of a particular water body. Once use classifications are assigned, water quality standards are applied to protect those uses from impairment (5 CCR 1002-31.3).
The use classifications recognized by the state are: recreation (class la, lb, and class 2), agriculture, warm water and cold water aquatic life (class 1 and class 2), water supply, and wetlands. Class 1 recreation is applied wherever primary contact with water may occur - the swimmable standard. Class 2 recreation provides for secondary contact where primary contact is not possible. The definitions of different recreation classes have recently been changed. These new definitions have not yet been applied to southwestern Colorado. Class 1 aquatic life, warm or cold water, refers to waters able to support a wide variety of aquatic life. Class 2 aquatic life refers to waters where there is some type of impairment to aquatic life - physical habitat, water flows or levels, or uncorrectable water quality conditions ~ such that a wide variety or abundance of species is not possible to sustain (5 CCR 1002-31.13).
If streams or lakes are not assigned an aquatic life use or recreation class 1 use, an analysis is needed to determine why these uses are not attainable and what uses are attainable (5 CCR 1002- 31.6(3); also see 40 CFR 131.10), Most of the segments in the Upper Animas Basin fall into this category and require a Use Attainability Analysis (UAA).
In addition, all of these segments are listed on the 303 (d) list. Section 303 (d) of the Clean Water Act requires that all water bodies be identified and listed that can not meet applicable water quality standards when technology-based controls are applied to point sources. For those listed water bodies, the lower levels of contaminants that must be reached to meet applicable standards need to be identified. Those levels are called Total Maximum Daily Loads (TMDL’s). Allocations of the TMDL’s are assigned to point, non-point and natural sources including a margin of safety such that the TMDL limits are met - meaning the standards are met. Information collected for the UAA will lead eventually to TMDL development for the Animas River segments listed on the 303 (d) list.
TRIENNIAL REVIEWS
Under both federal and state taw, water quality standards for all surface waters of the state must be reviewed every three years. In Colorado, the review is conducted by WQCC with assistance from WQCD. The last review for the Animas River was conducted in August 2000. Any actual changes in the use classifications and standards will occur in rulemaking hearing scheduled for March 2001.
The UAA provides recommendations and supporting documentation for appropriate use classifications and standards for river segments of the Animas River watershed. WQCC will use this information as part of their review. In 2003, WQCC will again conduct a triennial review for this part of Colorado and may decide to make further changes based upon new information.
CURRENT USE CLASSIFICATIONS AND STANDARDS FOR THE ANIMAS RIVER
This section summaries some important elements of the current use classifications and standards for the Animas River watershed (5 CCR 1002-34.6). For a full description of all attributes of the table, refer to The Basic Standards and Methodologies for Surface Water (5 CCR 1002-31) available through WQCC directly or on its Internet site. The location of different segments is shown on Figure 1,
Table 1.1 below is a reproduction of the actual use classifications and standards as presented in the regulation. The first column describes each segment. There are some problems in the descriptions that are discussed in the recommendations chapter at the end of the UAA.
The third column lists use classifications. Those segments that have no aquatic use designation have minimal if any aquatic life. Conditions that limit aquatic life in those segments are not considered correctable to the degree needed to support aquatic life. However, improving conditions in these segments is important because of their strong influence downstream segments where aquatic life exists.
The standards listed in the columns to the right of the use classifications are designed to protect all uses listed in the classification column. Generally, aquatic life uses need the most stringent standards to prevent any impairment. Thus, aquatic life needs drive most of the standards in segments where aquatic life is a use.
The segments which garner the most concern are those with “temporary modifications ” shown in the last column of the table. These are segments that have standards - called underlying standards - which are currently not being met. The temporary modifications make the standards less stringent to allow people time to comply with the underlying standards.
Note that the “temporary modifications” don’t go into effect until 6/30/01. This is an anomoly in the way the WQCC sets standards. WQCC took this approach because of the uncertainty involved in determining underlying standards.
In 1994, WQCC held a rulemaking hearing in Siiverton. Because of substantial disagreement between parties to the hearing, WQCC adopted WQCD’s recommendations for temporary modifications and underlying standards, but delayed the implementation date for three years to allow for the collection of more information. During the delay, the standards were set equal to ambient water quality, meaning that the existing water quality was the standard and it could not be degraded (5 CCR 1002-34.23).
During the next triennial review, in 1997, WQCC was presented with information showing substantial progress in addressing water quality issues in the Upper Animas Basin and with a request for more time to gather information and make recommendations for appropriate use classifications and standards. WQCC extended the delay of the implementation date to June 30, 2001, with the understanding that there would be no more delays (5 CCR 1002-34.37).
WQCC does not have the last word in setting water quality standards. Those standards must be approved or disapproved by the U.S. Environmental Protection Agency (EPA) (CWA § 303(c)). EPA disapproved some of the ambient water quality standards on segments 3 a, 4a, and 9b (Letter to WQCC, 8/27/98, Appendix 1). EPA will only approve ambient standards when an analysis shows that water quality problems are natural, or human-caused but irreversible (40 CFR 131.10). For those segments, no definitive analysis had been done. Ambient standards were approved on segments 2, 3b, 7, and 8. EPA agreed with WQCC that analyses had shown that these segments cannot support aquatic life now or in the near future. This UAA addresses the disapproved segments. In addition, since most of the metal loading for these segments comes from upstream, the analysis must also examine the loading and potential reductions in loading that may be accomplished in the upstream segments - 2, 3b 7 and 8 - in order to protect classified uses in the lower segments. TEMPORARY MODIFICATIONS AND REGION: 9 QUALIFIERS BASIN: ANIMAS AND FLORIDA RIVER METALS PHYSICAL INORGANIC and Stream Segment Description BIOLOGICAL _ug2_ Se(ch)=10(Trec) Astac)=50(Trec) Fe(ch)=300(dis) JH,(K)=TVS = 0.002 Ag(ac)=TVS Aq Lite Cold 1 0=60 r~g1 Cd(ac)=TVS(t7) Fe
Ag(ch}=TVS •Goal Hg(ch)=0.01(tol) As(c*if=50 Cu(3G,ch)i TVS NH^ac)=TVS S=0.002 Ni(ch)*TVS Aq Life Cold 1 D.O. = 6 0 m g ’! Cd(ac)=TVS(tr) Fe(ch)=300(dis) 4 b Mainstem of the Anim as R iver, including w etlands, from the 8=0.75 Se(di)=10 Recreation 1 D O (sc}“ 7 0 m g l NHjdl)=0.02 Cd(ch)=TVS Fe(e#i)s 1509{Trec) confluence with E lk C reek to the confluence w ith Junction pH = 6 5-9 0 c y « c ) * o o i9 N0j=0.05 Pb(ac/cii)=TVS Ag(scJ=TVS Water Supply cyt*)=o.oii N 0 s=10 Crtlt(ac/di)*TVS Creek Agriculture F.Cofi-200/100ml CrVI{ac/tfi)=TVS Mn(cft)=210 CN=0.005 CN250 S 0.=250 Tetrp mod effective fw Effectrve until June 30. 2001: Z n (c h )= ia 2 3 years beginning 6/30/01: Zn -S E E STATEMENT OF BASIS A N D PURPOSE H REGION: 9 Desig Classifications NUMERIC STANDARDS TEMPORARY | BASIN: ANIMAS AND FLORIDA RIVER MODIFICATIONS AND QUALIFIERS PHYSICAL ffiORGAMIC METALS Stream Segment Description and BIOLOGICAL Aq Life Cold 1 D O = 6.0 m ol W Ja c)= T V S S=0.002 Southern m e Indian Reservation boundary to the Colorado/New As(ch)=50 Fe(ch)=3tX)(dis> Se(ac/ch)=TVS Recreation 1 D O . (SP)=7 0 mg'! Mexico border. NH jchl=0.02 B=0.75 Cd(ae)=7VSftr) Fe{ch)=1000(Trec) Ag(ac)=TVS Water Supply pH = 6 5-9 0 C; pH - 4.5 - 9.0 Effective until June 30, 2001: 8 wetlands, from the source to a point im m ediately above the Agriculture F.Coli=20Qn00ml confluence with South Mineral Creek except for the specific UP listing in Segment 9a. Enstrng am bient quality for all metals as o f February 14,1995. Terrp mod eflsctvs fix 3 years beginning Effective a s o f June 3 0.2 00 1 : 6Q0/01: existing The concentration of dissolved aluminum, cadmium, copper, iron, lead, ambiertf quality for aft manganese, and zinc that is directed toward maintaining and metals. achieving w ater quality standards established for segm erts 3a. 4a. 4b. Aq Life Cold 1 D O . = 6 0 m g l NH^ac)=TVS wetlands, lakes and reservoirs from the source to a poinl 5=0.002 As ^q Life Cold 1 D O . = S.Omg1! NH,(ac)=TVS im mediately above the confluence w ith the S outh F ork lo the S=0.002 Ai(aoft#i)=TVS CrVt(ac/ch)=TVS -lg[ch)=0.01(lot) Recreation 2 D O. (sd)=7.0 mg1 confluence with the Anim as River. WH^ch)*0 02 B=0.75 As(ch>=100(Trec> Cu(ac)*TVS *(acfch)=TVS UP Agriculture F.CoH=200n00rr* Ci, BASIN: ANIMAS AND FLORtDA RIVER METALS PHYSICAL INORGANIC ani Stream S egm ent Description BIOLOGICAL m q l ______u a i Fe(ch)=300(dis) Ni(ac/ch)=TVS MH«(ac)=TVS S=0.002 As(ac)=50{Trec) Aq Life Cold 1 D 0 = 6 .0 m g l Fe(c#>)=l00Ò(TTec) Se(ch)=10(Trec) 10. Mainstem of the Florida Rivet from the boundary o f the B = 0 .7 5 Cd(ac)=TVS|tr) Recreation 1 0 . 0 - 7.0 m ÿ l NHJch)=0.02 Ag(ac)=TVS Wfcnwuche Wilderness Area to the Florida Farmers Canal M0j=0.05 Cd(cii)=TVS PblacAii^TVS Water Supply pH* 65-9.0 C y ’ac)=0.019 Ag(ch)=TVS D O - 6.0 mg'! 13b All tributaries to the Animas River, including all lakes and Aq Life C old 2 D.0.(sp)=7.0 mg'! reservoirs, from a point im mediately below the confluence with Recreation 2 pH =65-9.0 Hermosa Creek to the Southern Ute Indian Reservation boundary Agriculture F.Cc*=2000'100ml except lor the specific »stings in Segments 10.11,12a. 12b. 13a and 14; alt tributaries to the Florida River, induding an lakes and reservoirs, from the outlet of Lemon Reservoir to the confluence w ith tte Animas R iver, except lor specific listings in Segment 12a I REGfON: 9 Descg Ciass^cations NUMERIC STANDARDS TEMPORARY I BASIN: ANIMAS AND FLORIDA RIVER AND QUALIFIERS Stream Segment Description and BIOLOGICAL 13<_ All UibuUi>e> lo the Ammas River, mduchng an lakes and reservoirs, from the Aq Lrfe Co>d 2 D.O. • 6 0 r r g l Southern Ute Indian R eservation boundary to the Colorado'New Mexico UP Recreation 2 D.O.fso}=7 0 r r ç l border, except for the specific listings m Segments 10. 1 1 .12a. 12b. 13a and Agncu'ture pH = 6 5-9 0 H : all tributaries to the Florida River, including aS lakes and reservoirs, from F C oI'=2000'100tV Ihe outlet o f Lemon R eservoir to the confluence with the Anim as River, except for specific listings m S egm ent 12a. 14. Mains tem o f Lghtner Creek from the source to the confluence with the Aq Life Co*d 1 DO.5 6.0 m g l NH^a=)=TVS S =0 002 As(ac)=50frrBct Animas River. Fe(ch)=300 EPA Letter of Disapproval of Standards Sent to WOCC UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION VIII 399 18lh STREET ■ SUITE 500 DENVER, COLORADO 80202-2456 Ref: 8EPR-EP AUG 2 7 ’998 Mr. David Pusey, Chair Water Quality Control Commission 4300 Cherry Creek Drive South Denver, CO 80222-1530 Subject: EPA Action on the Revisions to the Classifications and Numeric Standards for the Upper Animas River Basin Dear Mr. Pusey: The U.S. Environmental Protection Agency (EPA) has completed its review of the revisions to the water quality standards for segments located in the upper Animas River basin. Our action covers two sets of revisions, those adopted by the Water Quality Control Commission (Commission) on February 13, 1995 and those adopted on December 8, 1997. These revisions were submitted to EPA Region V m in letters dated March 6, 1995 and December 29, 1997, respectively. Receipt of the submittal packages initiated EPA's review pursuant to § 303( c ) of the Clean Water Act (CWA) and the water quality standards regulation (see 40 CFR 131). EPA has completed its review, and this letter is to notify you of our action. EPA participated actively in both of these rulemakings and submitted comments to the Commission in letters dated July 28, 1994, August 22, 1994, December 27, 1994, September 22, 1997, and October 21, 1997. Our letter to the Water Quality Control Division (Division) dated September 5, 1997 included additional guidance regarding the requirements applicable to use attainability analyses and ambient-based (site-specific) standards development. We believe that these comment letters to the Commission, as well as our previous comment letters on similar site-specific actions across the State, provided timely and appropriate direction on the major options to achieve compliance with Clean Water Act requirements. It should be noted that the Animas River Stakeholders Group (ARSG) also participated actively in the rulemakings and is now proceeding with collaborative efforts to resolve many of the outstanding issues addressed in this letter. The ARSG includes representatives from elected officials, mining companies, environmental groups, local, state, and federal government agencies, and local interests such as the Historical Society and Southwestern Water Conservation District. The group is now working to collect river monitoring data, assess the impact of contaminants and channel modifications on aquatic life, evaluate the feasibility of cleanup actions, formulate implementation plans, and develop a use attainability analysis and water quality standards proposal. The Region looks forward to continued active participation with these ARSG efforts. CWA § 303( c ) requires States to submit new and revised water quality standards to EPA for review. EPA is to review the State submission and approve or disapprove the revisions. In this case our review was delayed because of our efforts to satisfy the requirements of §7 of the Endangered Species Act (ESA). An EPA approval is considered a federal action subject to the § 7 consultation provisions of the ESA. Under these § 7 requirements, EPA is to determine whether or not an approval decision may affect listed threatened or endangered species. We apologize for any inconvenience this delay may have caused the Commission or other interested parties. TODAY’S ACTION In today’s action, the Agency is approving the majority of the new or revised standards. We are, however, also disapproving certain elements of the water quality standards for segments located in the upper Animas River basin. This letter is to inform you of these actions. AppravedJWateiLQnality Standards All new or revised provisions are approved except as specifically noted below. The scope of our approval includes, for example, the Commission’s action to exclude aquatic life designated uses from the Animas River (segments 2 and 3b), Cement Creek (segment 7) and Mineral Creek (segment 8). We agree with these decisions and have concluded that the information provided in the Division’s Exhibit 3 (July 1994) constitutes an acceptable use attainability analysis under the requirements in 40 CFR 131.10. As part of our informal consultation with the U.S. Fish and Wildlife Sendee under ESA § 7, EPA has concluded that our approval action will have no effect on listed or proposed species. We^were particularly pleased with a number of the revisions that, in our view, represent significant improvements to the water quality standards for the upper Animas River basin. Specifically, we commend the decisions to: * upgrade the classification and numeric standards for new segments 3a and 4a of the Animas River - previously these segments were not classified for aquatic life protection, apply table value standards to protect the aquatic life use designated for South Mineral Creek below the confluence with Clear Creek, apply table value standards (for some parameters) to protect the aquatic life use designated for Mineral Creek below the confluence with South Mineral Creek, adopt temporary modifications and narrative standards (effective March 2, 2001) for various segments, • add the agriculture use to several segments, add the recreation 1 use or 200/100 ml fecal coliform numeric standard to several segments, and • re-segment the Animas River above and below the Southern Ute Indian Reservation boundary. These revisions represent significant improvements to the water quality standards applicable to the upper Animas River basin. The revisions will provide water quality requirements and goals to drive water quality restoration efforts, particularly the revisions which become effective March 2, 2001. We want to specifically acknowledge the work of the Division in the 1995 rulemaking. In addition to assembling and analyzing an impressive amount of data from a variety of sources, the Division ensured there was extensive opportunity for public participation and stakeholder involvement in developing the proposal. Disapproved Water Quality-Standards As indicated above, EPA is disapproving certain elements of the standards for segments within the upper Animas River basin. Where EPA disapproves an element in a State’s water quality standards, the Act allows EPA and the State 90 days to reach resolution and effect an acceptable change. Where resolution is not reached within 90 days, EPA is to promptly promulgate replacement federal standards. The disapproved provisions are as follows: 1) Segment 3a: The ambient-based standard for zinc of 540 ug/1 is disapproved. 2) Segment 4a: The ambient-based standard for zinc of 520 ug/1 (effective until March 2, 2001) is disapproved. 3) Segment 9b: The ambient-based standards for copper and iron of 57 ug/i and 5515 ug/1, respectively (effective until March 2, 2001) are disapproved. The basis for our disapproval is that we are unable to conclude that these ambient-based numeric standards are consistent with the requirements governing adoption of water quality criteria included in the federal water quality standards regulation (40 CFR 131.11). In reviewing the adopted ambient-based standards, we focussed on two issues: are the numeric standards based on methods that are acceptable, and do the numeric standards describe water quality levels that will protect designated uses? Of greatest importance in reaching our conclusion that the standards are not acceptable is the lack of supporting analyses ° demonstrating that the ambient-based standards are due to either natural and/or irreversible conditions. In addition, there were no supporting analyses demonstrating that the ambient- based standards would be expected to protect designated uses. On the contrary, the available toxicity information indicates that the disapproved numeric standards describe water quality levels that would be expected to result in toxic effects to sensitive freshwater aquatic species. It has not been demonstrated that achieving more protective water quality levels is infeasible. Based on the available information, including the information included in the Division’s Exhibit 3 (July, 1994), we are unable to conclude that the elevated water quality levels that are the basis for the ambient-based standards are caused entirely by natural or irreversible sources Additional discussion of the facts and analyses that support our disapproval action is included in Enclosure 1. OPTIONS TO RESOLVE THE DISAPPROVAL ISSUES CWA § 303(c)(3) requires EPA to identify State actions that will satisfy the requirements of the Act. In this case, there are several approaches that might be viable options tor resolving the disapproval issues, described below. Option 1. Adopt table value standards for the parameters of concern for the affected segments. This would be the most straight-forward approach for ensuring that the water quality standards will protect designated uses. There seems to be consensus that, followin* remediation, water quality will be better than that reflected in the adopted ambient-based standards. However, we acknowledge that it will be difficult to achieve table value standards tor these metals in the segments of concern. ; Option 21 Adopt temporary modifications for the parameters of concern for the affected segments with underlying numeric standards based on table values. This approach would provide additional time to plan, implement, and monitor remediation activities and/or develop alternative numeric standards. This is the option recommended by the Region because it is the approach that will satisfy Clean Water Act requirements in the shortest timeframe while also providing the flexibility to pursue needed site-specific water quality studies. Option 3 . Adopt different (site-specific) numeric standards based on a re-evaluation of the available data and following scientifically-defensible methods. One approach would be to adopt site-specific standards based on toxicological information that identifies water quality conditions protective of all species included in the potential aquatic community for the segment. EPA guidance on development of site-specific criteria is included in the Water Quality Standards Handbook (1994). Option 4. If additional information or analyses can be developed which demonstrates that the disapproved numeric standards are consistent with federal requirements and would be protective of the designated uses, a final option is to provide such information or analyses to EPA. As noted above, the Animas River Stakeholders Group (ARSG) is proceeding with a use attainability analysis (UAA) that will result in development of a water quality standards proposal for the upcoming triennial review. Eased on our understanding of the tasks that are being pursued under the UAA, the ARSG’s approach appears to be most consistent with Option 3. The Region is interested in continued active involvement in the ARSG efforts and will provide as much assistance as possible. For several of the tasks that the ARSG intends to complete, we acknowledge that more detailed national guidance would be useful. We hope that the approach developed and employed in this case will serve as a valuable model for similarly-impaired sites that have been affected by historic mining practices. Please note that the Region also remains interested in working with the State and other interested parties to develop detailed State procedures to guide development of ambient-based criteria under Section 3.1.7(l)(B)(ii) of Colorado’s Basic Standards and Methodologies for Surface Waters. CONCLUSION The watershed restoration work now underway on the Animas River is a model community-based environmental protection effort. As indicated above, we are impressed by and supportive of the work of the ARSG. We also recognize that a number of the issues the ARSG is attempting to resolve are common to sites affected by historical mining, and it is likely that techniques developed to address those issues on the Animas River will transfer to other sites. In this regard, the ARSG’s work can be considered groundbreaking. The ARSG is to be commended for its work. Despite these very positive aspects of the watershed restoration effort, we believe there is insufficient technical justification for a number of the numeric standards adopted by the Commission in 1994 and again in 1997. As a result, and as noted above, we have no choice but to disapprove those elements of the water quality standards for the Animas River basin. As we have indicated in this letter and previous correspondence, we believe an alternative approach, using temporary modifications, would have achieved the desired goal-setting function in a way that would have been consistent with State and Federal regulatory requirements. Nevertheless, we also acknowledge that the Commission’s decision took into account what might be considered the somewhat unique circumstances associated with the Animas River water quality standards issues. We cannot ignore the Clean Water Act and our regulatory requirements. Neither can we ignore the complexity of the water resource issues at this site and the extensive work now underway to address those issues, with their determination having a direct bearing on the disapproved standards. The Clean Water Act specifies that, following disapproval, States have 90 days to adopt the changes identified by EPA as necessary to satisfy the Act’s requirements. If the changes specified by EPA are not adopted within 90 days, the Act directs EPA to “promptly prepare and publish proposed regulations setting forth a revised or new water quality standard." These requirements provide little flexibility for multi-year research projects designed to address complicated site-specific water quality issues. Nevertheless, we strongly support the efforts of the ARSG. A use attainability analysis is now underway and we believe it is important to complete the planned studies as quickly as possible. The ARSG’s workplan aimed at establishing water resource goals for the Animas River is comprehensive, and it should provide sufficient information to derive site-specific standards. As we understand it, the ARSG’s intent is to bring the needed information to the Commission at the triennial review informational hearing for the San Juan, Gunnison, Dolores, and Lower Colorado River basins currently scheduled for August, 2000. The informational hearing will be followed by a rulemaking process, and conclude with a rulemaking hearing in February, 2001. We are supportive of the ARSG’s plans to resolve the site-specific standards issues. Consistent with the plain language of the Clean Water Act, we are also supportive of State action to resolve the disapproval issues in the short term. The Commission has the ability to put approvable water quality standards in place prior to February, 2001. The most straight-forward approach, Option 2 (discussed above), would be to adopt temporary modifications for the parameters of concern for the affected segments, with underlying numeric standards based on table values. We continue to recommend this approach because it would serve the dual puipose of satisfying the Clean Water Act while also allowing the ARSG sufficient time to complete its detailed site-specific studies, analyze the resulting data, and recommend water quality standards to the Commission for adoption. As we explained during the 1997 rulemaking process, the duration of a temporary modification is most appropriately* based on the time needed to conduct planning and remediation activities at the site in question (see, e.g., our September 22, 1997 pre-hearing statement). Although the Clean Water Act can be fully satisfied only by short-term resolution of disapproval issues, we also have confidence in the longer-term ARSG effort and believe that it will result in an information base from which appropriate site-specific standards can be developed. Again, despite the unique circumstances present in the upper Animas River basin and the ongoing ARSG project, we recommend prompt State action to adopt water quality standards consistent with Clean Water Act requirements. Absent State action to correct the disapproved standards, it may become necessary, at some point, for EPA to prepare and publish proposed federal standards. This would be unfortunate, and is an outcome that we have tried to avoid. If it does become necessary, it is important to remember that the proposed federal action can be halted or withdrawn as soon as approvable water quality standards are adopted by the State. The Commission and the Division are to be congratulated for the significant improvements to the water quality standards for the upper Animas River basin. Although the adopted revisions represent substantial progress, the issues outlined above and discussed in the enclosure suggest that further progress is possible. The Region looks forward to working with the Water Quality Control Division, the ARSG, and any other interested parties to resolve these issues as quickly as possible. If you have questions concerning this letter, please call me or Max Dodson, Assistant Regional Administrator, Office of Ecosystems Protection and Remediation, at 312-6598, or have your staff contact David Moon at 312-6833 or Bill Wuerthele, Regional Water Quality Standards Coordinator, at 312-6943. Sincerely, William P. Yellqwtail Regional Administrator Enclosure BASIS FOR EPA’S DISAPPROVAL The disapproved numeric standards are inconsistent with the federal requirements governing State adoption of water quality criteria. The water quality standards regulation at 40 CFR 131,11 requires that: States must adopt those water quality criteria that protect the designated use. Such criteria must be based on sound scientific rationale and must contain sufficient parameters or constituents to protect the designated use. For waters with multiple use designations, the criteria shall support the most sensitive use. Paragraph (a)(1). In establishing criteria, States should: (1) Establish numerical values based on: 304(a) guidance, or 304(a) guidance modified to reflect site-specific conditions, or other scientifically defensible methods. Paragraph (b). The Region is unable to conclude that the disapproved ambient-based numeric standards for zinc, copper, and iron satisfy these requirements. In reviewing the adopted criteria, we focussed on two issues: are. the numeric standards based on methods that are acceptable, and do the numeric standards describe water quality levels that will protect designated uses'? The principal issue is the lack of analyses demonstrating that the adopted ambient-based standards represent natural and/or irreversible conditions. Below, each of these issues is addressed for the ambient-based standards in question which were applied to segments 3a, 4a, and 9b. Issue # 1: Are the numeric standards based on methods that are acceptable? The methodology used to derive the ambient-based numeric standards at issue was to gather all of the representative water quality data for the affected segments, calculate the 85th percentile, and adopt that "ambient-based” value as the numeric standard. We considered whether this ambient-based standards methodology is consistent with federal requirements. EPA s water quality standards regulation does not specifically authorize ambient-based criteria. Instead, section 131.11 requires that criteria ''protect the use'1 and be based on “304(a) guidance, 304(a) guidance modified to reflect site-specific conditions, or other scientifically defensible methods." However, the feasibility of remedying man-induced pollution is specifically addressed in section 131.10(g)(3), which authorizes removal of a designated use where "human caused conditions or sources of pollution prevent the attainment of the use and cannot be remedied or would cause more environmental damage to correct than to leave in place.' Further, section 131.10(g)(1) authorizes use removal where "naturally occurring pollutant concentrations prevent the attainment of the use." EPA’s policy is that these two factors may also be used as a basis for establishing a variance from applicable water quality standards. EPA Region V m approved Colorado’s ambient-based standards provision1, despite the lack of a specific reference to ambient-based criteria in 40 CFR 131.11, because of our determination that in situations where “human caused conditions'1 or "naturally occurring pollutant concentrations" may be a basis for removing the designated use under 40 CFR 131.10(g), it is more protective and therefore also acceptable to maintain the designated use and establish ambient-based criteria. It was also our conclusion that, in either of these two situations, such criteria would protect the aquatic life use that currently exists or is attainable. In the "human caused conditions" situation, admittedly, such waters may not be able to support the full range of aquatic species that the natural habitat and water quality would support, but if the existing water quality conditions truly are irreversible, establishing ambient-based standards will ensure that existing conditions do not deteriorate further and provide protection for the aquatic species that constitute the existing and potential aquatic community in the segment. Thus, the ambient-based standards approach is acceptable to the Region where pollutant concentrations exceed levels of concern, but only where the elevated levels do not include the influence of reversible, anthropogenic pollution sources. Although we acknowledge that there are likely to be various natural sources of zinc, copper and iron in the upper Animas River basin, we cannot conclude that the existing elevated levels are entirely the result of such natural sources. Likewise, although some increment of the existing anthropogenic loadings are likely to be irreversible for the foreseeable future, we cannot conclude that the existing elevated water quality levels are entirely the result of a combination of natural and irreversible sources. We believe that some portion of the loadings of these pollutants is reversible, and that there are efforts currently underway to improve water quality conditions. Indeed, the Commission reached the same conclusion when it adopted temporary modifications (effective March 2, 2001) for the segments and parameters in question: The starting point for the Commission’s analysis is a conclusion that appears to be shared by most, if not all, of the participants to this rulemaking proceeding: current water quality in the Animas River Basin can and should be improved. (Statement of Basis, Specific Statutory Authority, and Purpose; September 12, 1994 H earing). 1 This provision is found at Section 3.1.7(l)(B)(ii) of Colorado’s Basic Standards and Methodologies for Surface Waters. The Animas River Stakeholders Group reached a similar conclusion: All stakeholders agree that current water quality can and should be protected from any further degradation; all agree that there are opportunities to make improvements, and that improvement is desirable even if it were not mandated; all agree that the task before us now is to identify the sources of significant human-caused loadings and find ways to remediate them. (Statement of the Animas River Stakeholders Group - 1994). Further evidence that water quality improvements in the segments in question are feasible and desirable is that the upper Animas River is included on Colorado’s 1996 and 1998 CWA 303(d) lists. Since ambient-based standards are acceptable to the Region only where they are derived using a method that excludes the influence of reversible anthropogenic pollution sources, and since it is not in dispute that the approach applied in this case does not meet that test, we feel compelled to disapprove the ambient-based standards in question. Issue # 2: Do the numeric standards describe water quality levels that will protect designated uses? Analyses have not been provided to EPA that support a conclusion that the ambient-based numeric standards in question will protect the Class 1 or Class 2 coldwater aquatic life designated uses that have been designated. The Division’s Exhibit 3 does include the statement that, for zinc, the magnitude of the ambient-based standards is less than the criterion for brook trout. However, since the brook trout species is not particularly sensitive to zinc and is but one of the species that should be protected under a broadly defined coldwater aquatic life designated use, we cannot accept this rationale. Description of the existing aquatic life use in these four segments was included in the Division’s Exhibit 3. This information indicates that there is aquatic life in these segments, but the aquatic life uses are limited, particularly in segments 4a and 9b. The biological assessment information does not demonstrate that the existing water quality conditions are supporting the Class 1 or Class 2 coldwater aquatic life designated uses. Of course, there may be stressors other than elevated concentrations for the parameters of concern that are limiting the aquatic life potential of these segments. Information on existing aquatic life in the three segments, from the Division’s Exhibit 3 (1994), included the following: Segment 3a "Electrofishing in 1992 found brook trout at several locations in the Animas River between Maggie Gulch and Cement Creek. Brook trout represented m ultiple age and size classes suggesting that they are self-reproducing. The mean relative abundance of macroinvertebrates ranged from 153 to 1305 organisms per square meter. Segment 4a “The WQCD found no fish below Mineral Creek above station A-72. A few brook trout were present at the lower end of the segment above Elk Creek (A- 73) The mean relative abundance of macroinvertebrates ranged from 20 to 8J organisms per square meter at A-72 and A-73, respectively. The abundance and diversity of both fish and macroinvertebrates is lower m this segment than m segment 3a.M Segment 9b “The Division electrofished the segment in 1992 near the confluence with the Animas River. No fish were found. Macroinvertebrate mean relative abundance per square meter at one site was four organisms. The ambient-based numeric standards at issue are less protective than EPA's national^ water quality criteria recommendations that have been published pursuant to CWA § 304(a) Although this fact alone does not compel EPA to disapprove, the comparison is worth makw0 because adoption of numeric standards more protective than § 304(a) criteria is acceptab e regardless of the derivation methodology that was utilized. Zinc The disapproved numeric standards for zinc are 540 ug/1 (segment 3a) arid 520 ug/1 (segment 4a). Hardness values for the segments of concern, based on data included ir.the Division’s Exhibit 3 (1994), vary between sites within the segment and are likely to vary from sample to sample. Table 1 is a comparison of the disapproved ambient-based standards for zinc to EPA’s 1987 national criteria recommendations (rounded to two significant figur®s)- This comparison demonstrates that the disapproved numeric standards are considerably less protective than the acute and chronic criteria recommended by EPA at hardness levels likely to occur in the affected segments. Table 1 - Comparison of EPA’s National Dissolved Zinc Criteria ______to the Disapproved Numeric Standards for Dissolved Zin_c_ Com bined Avr 1987 EPA Criteria (ug/1)** Disapproved H a r d n e Ï . J, „ CaCQ;) Acute______Chronic------N u m J ^ d _ TÏ9 Ï20 540 130 120______520_ ^ melCombined'average hariness values are for all monitoring stations located within the segment uuiuuuicu,combined, ao as reported by ^ ...the------Division in Exhibit 3,. 1994. ** The EPA zinc criteria published in 1987 are slightly more stringent than those included in the “1995 Updates" (EPA, 1995). For example, at hardness of 119 mg/1 as LaLU3, the dissolved zinc criteria in the 1995 Updates are 140 ug/1 (acute) and 140 ug/1 (chronic). The ambient-based standard for zinc assigned to segment 9b was approved because the acute table value standard that was also assigned is adequately protective. The underlying numeric standard for zinc assigned to segment 4a (effective March 2, 2001) was approved because it appears to be a reasonably protective and defensible estimate of the zinc concentration that will protect brown trout. There is considerable uncertainty surrounding the 225 ug/1 zinc numeric standard, however, and we recommend that all interested parties collaborate to review the available toxicological information and identify the zinc concentration that will be protective of all species included in the potential aquatic community in segment 4a. This analysis should include any new information on the toxicity of zinc to brown trout, including but not limited to new data developed by the Division of Wildlife. Copper. The disapproved chronic numeric standard for dissolved copper is 57 ug/1 (segment 9b). Hardness levels, based on data included in the Division’s Exhibit 3 (1994), vary between sites located within the segment and are likely to vary from sample to sample. At the average hardness value of 136 mg/1 for the segment reported by the Division (Exhibit 3, 1994), the disapproved chronic standard for dissolved copper is less protective than EPA’s national dissolved copper criteria recommendations- Specifically, 57 ug/1 is less protective than EPA’s 1984 one-hour average recommendation of 23 ug/1 (to prevent acute effects) and four-day average recommendation of 15 ug/1 (to prevent chronic effects). Note that the 1984 EPA copper criteria are slightly less stringent than those included in the "1995 Updates" (EPA, 1995). At the average hardness level for segment 9b, the dissolved copper criteria recommended in the 1995 Updates are 18 ug/1 (acute) and 12 ug/1 (chronic). Although an acute table value standard for dissolved copper is also assigned to segment 9b, the ambient- based chronic standard was disapproved because of our concern that neither the acute table value standard nor the ambient-based standard appears to be adequate to prevent chronic effects. Iron. The disapproved numeric standard for iron on segment 9b is 5515 ug/1. This numeric standard is expressed as total recoverable iron. The disapproved standard is less protective than the 1000 ug/1 national criterion for iron recommended by EPA to protect aquatic life. We note that ambient-based standards for total recoverable iron applicable to segments 4a and 4b were approved because the numeric standards for dissolved iron that are applicable to those segments are adequately protective, i.e., 390 ug/1 (segment 4a) and 300 ug/1 (segment 4b). Iron is somewhat unique in that the principal adverse effect appears to be related to the formation of iron hydroxide precipitates and the smothering effect these precipitates have on the benthic life stage of fishes and on benthic invertebrates. There is information in the literature and there are site-specific field observations suggesting that concentrations above the 1,000 ug/1 value could be protective of aquatic life uses based on site-specific factors. It is possible, therefore, that there are situations where a value other than the 1,000 ug/1 could be acceptable as a site-specific standard. At this point, however, there is neither an analysis from the Division showing that the 5515 ug/1 value is due to natural and/or irreversible conditions nor an analysis demonstrating the 5515 ug/1 value is protective of the designated uses at these specific sites. CHAPTER II - Protecting Existing and Potential Uses Sources of contamination to water resources fall into two categories point sources. Point sources are locations w h e r e water has requirements (e.g. regulations on the application of pesticides). POINT SOURCE PERMITS Bpfi*iSS¡EPA)6 ^ 6 developed comprehensive descriptions of BMP’s for WQCD’s Non-Point Source effluent limits and monitoring r r rr Ds " r ■£ h x s z z r - a s s s s s s s s x s & s s z - state has been delegated to administer these permits. ■ a «+ oil mini» cit^s if stormwater conies “into contact, or is a s » » » » * - mixed with other sources of contaminants, a process water permit may be needed, industry disagree with this opinion (Mining Water Quality Task Force, p. 7). per r « r ^ stormwater^ permit, a site must be reclaimed such that runoff potential sources of contamination, erosion is controlled, and the site is revegetatea. f General Permit, p. 14.) ENFORCEMENT he vast majority of inactive and abandoned mine sites in Colorado do not have the requisite water quality control permits. There are thousands of sites around the state, and because of limited resources the state has made permitting these sites a low priority at this time For example while there may be 1,500 mine sites and 200 draining mines in the Upper L m a s Basin, there are only five process water NPDES permits (including the Silverton wastewater treatment plant) and only 14 mining-related stormwater permits. Generally, permitting is only enforced when a property owner plans to take some physical action on his or her property pa lcularly to renew mining activities. Depending on resources and political climate the level of enforcement may change in the future. Not only are current properly owners liable for these NPDES permits, but past owners operators or anyone else who has worked on a site can also potentially be held liable for discharge of actions A r l h°s °f pot®ntlal ,iability is a significant barrier to “Good Samaritan” actions. A Good Samaritan can be government agencies, private companies, or volunteer , of thf e partl®s ma-y want to remediate or partially remediate an inactive or doned mine site that they do not own. However, someone has responsibility for the PermUS untl1 l*Jose Permits can be terminated. Most groups acting as “Good amaritans are concerned that if they do any even minor work on a mine property, they may be held liable any contaminant discharge from the site. A number of remediation projects around the state have been put on hold because of this liability ? r u , T f e ™ tly eff0rtS t0 push a “Good Samaritan” provision through Congress to limit liability for third-parties working on others’ property. Depending on how it is written such a provision could have a substantial beneficial impact on volunteer remediation efforts in the Upper Animas Basin. NON-POINT SOURCE PROGRAMS Pollution sources that do not fall under the point source category are considered non-point addr«« th arE discharges that are more difficult to manage. Programs designed to t S eS? are USUally voluntary and consist Of information, education, and funding rfM to S T , I r T Pm8T S arer thr0Ugh the Water Quaii*y Controi Divis.on, Division Minerals and Geology, and Hazardous Materials and Waste Management Division All of these agencies have extensive experience and expertise in mining-related water quality issues. ^ o n l!,hf p p f 0Vernment ftlnding f°r remedlat,on on inactive “ d abandoned mine sites has come 1 th ^ u non:polnt souroe contro1 »rants administered by the state. These grants are noiution y Se°* T 19 °f the CWA 8nd 8re US6d Specit'lcal‘y ^dress non-Po!nt source po lution. In recent years, a number of these grants have gone to the Upper Animas Basin be°r T P; f : r : ° ; cenied that thlS iUnding may not be available for site remediation because EPA has had an increasing tendency to classify mine sites as point sources. In addition to the 319 funds, several state and federal agencies have funded remediation when the efforts fell within the missions of these agencies. This is discussed in the next chapter. CERCLA Mine property owners in the Animas Basin potentially could be required to remediate their sites under the provisions of the Comprehensive Environmental Response, Compensation and r- KT+ Apt irvMCi A 42 tJ S C 88 9601) This legislation is best known by the Superfund “ S' S c o E iS W « oJiO Si»« «sood legislation could affect inactive and abandoned mine properties (Mining Water Quality Task Force, p. 7.): CERCLA permits EPA and others to undertake and ensure the cleanup of hazardous substance releases posing threats to public health or the environment. Hazardous substances include toxic heavy metals. CERCLA permits any person to recover “response costs” (i.e., costs associated with remedying ° y " y estl^ n8 a substance release) from potentially responsible parties (PRP s). These PRP s may include: the current or past owner or operator of a facility; persons who arranged for disposal” of hazardous substances; and transporters of hazardous substances. Courts have consistently interpreted a PRP’s liability under CERCLA as strict and joint and several. In addition, CERCLA provides only limited statutory defenses to liability. Given CERCLA’s broad scope, it presents significant remedial and liability implications for PRP’s at mining sites. For example, CERCLA liability can be imposed retroactively, and therefore, historic activities undertaken by a mine owner or operator at some time in the past, and although legal at the time, may give nse to CERCLA liability. Also, CERCLA provides little relief to entities who may initiate a voluntary clean-up at an inactive or abandoned mine where, for example, a release o h a z a r d o u s substances occurs during remediation or if a residual release remains after remediation is completed. Federal reaulatory agencies (EPA, Forest Service, Bureau of Land Management) have some discretion in applying CERCLA. For example, these agencies do not necessarily have to pursue S ks stsss srisa z z t s s f f s m s “ a i Water Act section 319 nonpoint source program.” (Mining Water Quality Task Force p. 13). Unfortunately there is not an agreement that would limit the states liability exposure they chose to remediate a draining mine. Forest Service and Bureau of Land Management use their CERCLA authority w ^n remediating ‘nactwe or abandoned sites on their own property. These agencies require a search for PRPs, such as past operators, which may result m full or partial cost recovery. LANDOWNER PERCEPTIONS Many property owners of abandoned and inactive mines maintain a low profile, not wanting to attract attention. These owners are unclear as to what actions they might need to take and how much it might cost to meet their liabilities. Stormwater permits have fairly minimal requirements and are inexpensive implement and maintain, but those requirements could change in the future. Process water permits - which generally require water treatment - are much more costly, especially in remote areas, and very difficult to terminate. Other owners wish to do something with their properties and areworking to reduce their liabilities. They may want to sell, redevelop or mine their land and reduction of liabilities may make the land more valuable. Some of these owners feel that their sites may contribute substantial metal loads and want to reduce their liability now in a more voluntary fashion under the current regulatory climate. If they are forced into obtaining permits for a site through a regulatory action, they may have less flexibility in working with the regulatory agency. The prospect of CERCLA actions is consideredto be particularly onerous by many property owners. Under CERCLA, regulatory agencies can force remediation of a site or do the remediation itself and require reimbursement by PRP’s. CERCLA actions in the Basin may scare off potential buyers or investors, reducing property values. They may also scare off mine site owners who might be willing cooperators in remediation efforts. While EPA has made good faith efforts to assure mine site owners that CERCLA actions may be applied in a more gentle, cooperative fashion than in the past, most site owners are still wary. Another important landowner perception is the issue of fairness. Most mine sites in the Upper Animas Basin have not been mined in eighty to a hundred years. Most owners did not participate in mining on their sites nor did they receive direct financial benefits from the mining. In terms of environmental regulation, virtually all mining activity was done legally at the time. While a number of sites may have measurable impacts on water quality, the majority of sites contribute minimal metal loading. (See Chapter XI.) In addition, there is a substantial amount of natural metal loading to the system. Some people feel they may be swept up in a national regulatory framework that does not have the flexibility or funding, to adequately address the situation in the Upper Animas Basin. REFERENCES CDPS General Permit, Stormwater Discharges Associated with Metal Mining Operations and Mine Waste Remediation, Permit No. COR-040000, Aug. 20, 1996. Report and Recommendations Regarding Water Quality Impacts from Abandoned or Inactive Mined Lands, Colorado Mining Water Quality Task Force, July 1997. CHAPTER III - ADDRESSING WATER QUALITY Sorting out issues of fairness, practicality, and cost-effectiveness in trying to improve water quality in the Upper Animas Basin, is a daunting task. It is especially difficult given the current framework of environmental law and regulation, and current level of resources. practices used in other places to manage other types of water quality problems may not work well here. Recoenizing these difficulties, the Colorado Water Quality Control Division (WQCD) asked a non-profit the Colorado Center for Environmental Management (CCEM) to facilitate meetings of potentially interested parties - stakeholders. Meetings began in early 1994 in Silverton and were geared towards finding consensus regarding water quality classifications an d standards for an upcoming Water Quality Control Commission (WQCC) rulemaking hearing held mS.lverton in September. The only consensus reached was to work together to improve water quality in th Animas River. ANIMAS RIVER STAKEHOLDERS GROUP Since these early meetings, an ad hoc group of individuals representing a wide variety of interests has been meeting almost monthly to address water quality issues in the Basur The Animas River Stakeholders Group (ARSG) has no formal organization. Any interested party cm come to meetings and participate as a stakeholder. Decisions are made by consensus, or at least acquiescence % som e members. The group hired a coordinator in 1995. It bu.lt a rela .onship with a non-profit in Durango to manage grants - the San Juan Resource ^ ns^ f ^ n “ Development Corp. (SJRCD), an offshoot of the Natural Resource Conservation Service in the Department of Agriculture. A list of participants is shown in Figure 3.1. Figure 3.1 Participants in the Animas River Stakeholders’ Group Alpine Environmental Services RiverWatch Network, Inc. Colorado Center for Environmental Management Root and Norton Assayers Colorado Dept, of Public Health & Environment St. Paul Lodge Colorado Division of Minerals and Geology San Juan County Commissioners Colorado Division of Wildlife San Juan County Historical Society Colorado Geological Survey Silver Wing Co., Inc. Colorado River Watch (local schools) Silverton, Town of Southern Ute Tribe Durango, City of Southwestern Colorado Water Conservation District Durango and Silverton Narrow Gauge Railroad Echo Bay Mines Ltd Sunnyside Gold Corp. Fort Lewis College TUSCO Friends of the Animas River U.S. Army Corps of Engineers U.S. Bureau of Land Management Gold King Mines U.S. Bureau of Reclamation Little Nation Mining U.S. Environmental Protection Agency Mineral Policy Center Mining Remedial Recovery Co. U.S. Forest Service U.S. Geological Survey OSIRIS Gold The mam impetus for ARSG’s continued existence is first, a desire to have some local control m Z d; C‘,Sr SffeCtlng the Vi’p e r Animas Basin’ and second> a realization that organizations must pool their resources to effectively characterize and address the very complex water quality issues m the watershed. Participants understood early in the process that nobody has a complete understanding of where the sources of metal loading are or what can be done about them It is a learning experience for everyone. ABANDONED MINED LANDS INITIATIVE Approximately 85% of the land in the Upper Animas Basin is under public ownership A large number of abandoned mines are located on U.S. Forest Service (FS) or U.S Bureau of Lafd Management (BLM) property. There are thousands of abandoned sites on public lands throughout the West. To better understand how to handle problems these sites may create the Department of Interior began an Abandoned Mined Lands Initiative (AML) in 1997 to study two £ in aX xtonnei999)e B°Ulder dnlina8e *” M°ntana a"d the 0ther is the UPPer The Initiative is an interdisciplinary, watershed based study designed to characterize metal oading sources and their effects on aquatic biota, discover methods to reduce those loads and e x p S f r o m a 7 m h n PT C'S' ^ WOTk combines a wide ran«e of scientific disciplines and expertise from a number of government agencies. The objectives of the Initiative are to: * f>ff^«nf1t theJPhyiliCa1’ cl)emj ca1’ and biological processes that control the environmental effects of abandoned mine lands, ♦ Refine the extent of contamination and of adverse effects on the aquatic ecosystem, . T. pre' mi”mg h&ck^onnd conditions to establish realistic targets for cleanup activities Identify sites that most substantially affect watershed quality and public safety, enabling resources to be invested where they will provide the greatest good ♦ Develop scientific information and methods to characterize contamination, evaluate human and environmental health risk, and design and monitor remediation * I:aaB S - SI™ f h0dS mkf0? ati°n t0 federal land ™"agement agencies and industry to enable efficient clean up of abandoned mine lands nationwide.” (Buxton, 1999, p. 9) A number of studies from the AML Program have been used in this UAA for characterizing the watershed. Reclamation work has begun on several public land sites. So far, nearly $6 million M ntfT th 1° a Basin’ mostly for characterization. (Robinson, unpublished data sheets) Most of the work under the Initiative has been completed and reports are being generated. WATERSHED CHARACTERIZATION w i s h L ^ T h i i nrTn by- ^ T ^ dT “ der *he AML pro«ram has been characterizing the thow I ♦ includes identifying and understanding the sources of metal loading and how Ind L h it^ ranT ° rte ldentlfym8 factors that may limit aquatic life such as metal loading and habitat, and analyzing sediment data for metal concentrations pre- and post-mining The paragrap bnefly summarize some of the data that have been collected. Later chapters describe the results of analyses of the data. The shear size of the Upper Animas Basin and multitude of loading sources, whose contributions change with the seasons, has made watershed characterization a monumental task. The Basin includes three major drainages: Mineral Creek, Cement Creek, and the Animas River. It covers 146 square miles - 93,000 acres (Leib, 2000) and has over 1,500 patented mine sites. U.S. BLM has inventoried another 300 unpatented sites on its lands. (Hite, 1995) In addition, the Colorado Geological Survey inventoried sites on U.S. Forest Service land in the La Plata and Animas River drainages and found over 800 sites. The majority of these were in the Upper Animas Basin. ( Lovekin et al, 1997) While all of these sites contribute substantial metal loads, a large amount of loading comes from non-identifiable sources. Water Quality Data Some of the first investigations into water quality on the Animas River occurred in the 1960 s. More water quality work and a couple of biological studies were completed in the 1970 s. These reports are summarized in a report by Allen Medine (Medine, 1990). A use attainability analysis was conducted on the Upper Animas River and Cement Creek in 1984 by Western Aquatics for the Standard Metals Corp., owner at the time of the Sunnyside workings (Western Aquatics, 1985). All of these studies identified heavy metal loading as the main inhibiting factor to aquatic life. It is difficult to compare much of chemical and biological data from these earlier investigations to studies conducted in the 1990’s because the parameters measured and field and analytic techniques used were frequently different than those measured and used today. However, it does appear that there have been definite improvements in water quality and biologic health of the Animas River. Some of the same chemical parameters have improved and more fish have been found in the Basin. From 1991 to 1993, WQCD collected substantial amounts of chemical and biological data for the 1994 rulemaking hearing discussed in Chapter I (WQCD, 1994). The information identified the main, general source areas for heavy metals. These studies have been greatly expanded upon by ARSG and the AML program throughout the nineties. The early nineties data included a wide variety of constituents because no one know exactly what might be impair aquatic life. Samples were tested for a full suite of metals, The metals that appear in concentrations that cause concern are; aluminum (Al), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), and zinc (Zn). In addition, the Colo. Dept, of Public Health and Environment under CERCLA funding did extensive sampling for organic chemicals that might affect aquatic life. They found virtually none. (Farrell Price, 1999) Results are discussed in Chapter VIII. Four gaging stations have been set up and maintained for the past seven years in the Basin. Two stations are located at the mouths of Mineral and Cement Creeks as they flow into the Animas. The other two are located on the Animas; one just above the confluence with Cement Creek and the other below the confluences with Mineral and Cement Creeks (below Silverton). This last site is referred to as A-72. Water quality data is generally collected monthly at these sites by a variety of different entities. High flow and low flow synoptic (meaning same day) samplings have been done on all three major drainages - eight synoptic samplings altogether. Each synoptic sampling on Mineral and Cement Creeks was run in one day. The Upper Animas River was broken into two parts, above and below the old townsite of Eureka. These sampling events involve taking flow measurements and water quality samples at fifty to eighty different locations along each main stem, bracketing incoming tributaries. All draining adits in each sampling area were sampled the next day. These efforts, involving personal from many agencies and a number of volunteers, provide the basis for determining metal loadings from different areas. In addition to the synoptic samplings, eight tracer experiments have been run at various locations. Tracer experiments were run over the entire length of Mineral and Cement Creeks and significant parts of the Upper Animas River during low flow. Other tracer experiments were done on particular sub-segments in the Basin. Tracers give an accurate snapshot of metal loading to a stream because groundwater contributions can be calculated. The tracer, usually a salt, is injected into the stream at a consistent concentration. Water samples are taken at intervals, perhaps a hundred yards apart, over a stream segment to be tested. By measuring the dilution of the salt concentration at each interval, the in-flow of water between intervals can be determined, if the flow of all surface water entering between sampling sites is measured, the groundwater inflow can be calculated. Water samples are also analyzed for metal concentrations. Therefore, sources of metals, including groundwater sources, can be precisely identified. (For a much greater description of the process, see Kimball etal, 1999.) Very intense water quality sampling was done in three smaller, sub-basins in the area. Every seep, spring and draining adit that could be identified was sampled and flow measured. By comparing all of these loads to the load found at the mouth of the drainage, the relative contributions of natural versus human-induced metal loading could be estimated (Wright, 1997). Different companies and agencies also did substantial sampling around potential remediation sites. Sites that have been or are undergoing remediation are listed in Table 3.1 below. Overall, a total of about 5,000 water quality samples have been taken. Waste Rock and Tailings Piles Using grants obtained by ARSG, the Division of Minerals and Geology collected composite surface samples of approximately 160 mine waste piles and tailings. Samples were uniformly subjected to a water leach test to determine their leaching potentials for acidity and dissolved metals. These samples give indications as to which piles may need remediation work. Sediment samples were collected from the river bottom along the entire 110 mile length of the Animas River to help determine the sources, fate and transport of metals. (Church et al.y 1997) Older sediments were also collected at historic river channels to analyze the changes in metal concentrations from pre- to post-mining periods, (Church et a l 2000). Biological Data Macroinvertebrate data has been collected three times at approximately fifty sites throughout the length of the river. This information has been analyzed to provide a benchmark which can be used to compare to the effects of iuture remediation efforts. The initial impact of improvements in water quality will most likely show up in macroinvertebrate counts downstream. in addition, sampling methods, sites, analytic methods, and metrics for iuture evaluations have been established. Work is also being concluded for developing species lists, possible indicator species, and sensitive species for stream segments. The Colorado Division of Wildlife (DOW) and others have done several electro-shocking fish studies throughout the watershed including both around Durango and in the Upper Basin. Surveys have shown improvement in fisheries between 1992 and 1998. Other biological studies have examined factors that might limit aquatic life. These include: toxic thresholds of three species of trout for specific metals, toxicity of water in the pore space in the substrate, the biological impact of smothering of the substrate with iron and aluminum colloidal deposits (or precipitates), and physical habitat attributes and limitations. Geology and Initial Remediation Plans The Colorado Division of Minerals and Geology and U.S. Geological Survey have mapped and described many of the geologic features in the Basin that can be sources of metal loading and/or buffering. The Division also devised preliminary remediation plans for most of the inactive and abandoned mine sites throughout the Basin. (Herron et al, 1997, 1998,1999,2000) Overall a prodigious amount of effort have gone into characterizing the Upper Basin. So far over $7.2 million has been spent. Some work is still in progress. Figure 3.2 shows funding sources for characterization and coordination in the Basin over the past ten years. Yet with all of these resources committed to characterization, even more resources have gone into actual remediation. Figure 3.2 - Funding tor Characterization and Coordination State Govt . DO_ 8% ARSG EPA Grants Local Govt u, 2% 7% Other Federal 9% Source: Rob Robinson, U.S. BLM, Denver, CO, unpublished spreadsheet on expenditures in the Upper Animas Basin plus personal communication with other stakeholders. REMEDIATION A number of sites have been remediated in the Upper Animas Basin. Most of the work has been Basin SGC entoPd Corporation (SGC), owner of the largest, most productive mine in the D v L n ? W 0 fm tfffa ^ ° o f nt ? eCree a8reement with the Water Quality Control sion (WQCD) effective May 8, 1996. This agreement provides a settlement to a dispute pNm- Se,eP^ al SpnT f may result from bulkhead closures of the Sunnyside Mine to eliminate discharges through the American Tunnel and Terry Tunnel. tnhnff8? elT nt* Pi0VideS f°r SQC t0 imPlement Permitted mine remediation projects in the Basin closwe K ? V T * v ° ^ qUali,y fr0m S6epS 8nd Sprin8S that may result from the the n s r s t ‘ mlt'8f °" PrW wil1 be measured at a reference point (A-72) which is suLessSlf mrno I T °X » h™ 8 ^ bei0W SUvert0a In order for ^ agreement to be S S S n n dls/ oIved zmc concentrations at A-72 must not increase when statistically compared to a reference data set over a time period specified in the Decree. T nnn^lT 6^ 1 comPietion’ the NTOES permits for the American Tunnel and Teiry BasTfor7 W 1 temllnuated by WQCD 311(1 SGC ^ v e no future liability in tte This aSio^f wiliePll f-PrT 8c re?Ult fr0m bulkheading the tunnels to eliminate discharges This action will allow final Sunnyside Mine reclamation. So far, SGC has spent over «10 million on reclamation in the Basin and does not plan to spend much more under the Decree. ^ r; med a r ° : Pr° ^ ? in *he BT have been partially &nded the 319 Non-Point Source ' nth hPr0Jt SPOnSOrS have been sma11 private mini"8 companies and property ” S- ^ hers have been sponsored by ARSG. In addition, remediation projects on pubHc lands have been funded through the AML Inititative. Funding sources for remediation are broken up into two charts, Figures 3.3 and 3.4. The first displays the percentages of funding for all remediation efforts. The vast majority of the funding comes from Sunnyside Gold Corp. The amount of funding spent or currently committed to remediation totals approximately $12 million - about $11.5 million has been spent. The second chart is a subset of the first and shows funding for voluntary remediation - that which was not tied directly to a regulatory settlement or action. For some of these projects, funding is committed, but work has not been done. All of EPA’s funding is in the form of 319 grants which are awarded and managed by the WQCD. ARSG’s funding consists mostly of in- kind services and volunteered time. The total funding represented by this chart amounts to $2.1 million. Figure 3.3 - Funding for Remediation Figure 3.4 - Funding for Volunteer Remediation AML Mining Co'e 7% EPA Grants 12% v i 6% O ther Mining C o's ^ 3% ^umiyside Gold 82% Source: Rob Robinson, U.S. BLM, Denver, CO, unpublished spreadsheet on expenditures in the Upper Animas Basin plus personal communication with other stakeholders. Table 3.1 below summarizes completed or on-going remediation efforts in the Basin. It does not include some projects that are funded, but have not yet begun. The Figure 3.5 shows the locations of projects listed in Table 3.1. Figure 3.5 Remediation Site Map N Denver Lake Sun Bank Group _/ & - G oid P rince <§?/' \ ■ . _ N c?l • I Lake Emma-. ) ) Joe&John \ Lark Carbon Lakes/San Antonio Bold King \ Silver Wing Kohler/Longfellow « A Galena Queen ^ Ransom Ad)t Lead Carbonate X . . . [ / __ Eureka Tailings M am m oth T u n n e l/ AmericaÀTunnel Forest Queen • Mine Site A Tailings Site Upper Animas River Basin Silverton, Colorado Table 3.1 Summary of Reclamation Projects n \ Improvements factual or (5) Project (61 Funding (3^ Location (A\ Type of Remediation (1) Project (2) Project Timeframe (incl. in-kind anticipated) Sponsor Site Name match) Reduce loading of metals and Removal of 27,000 yards of Completed SGC: $163,000 Sunnyside Lead Gladstone on erosion transport of tailings tailings from streambank 1991 Gold Carbonate bank of S. Fork of Cement Creek Corp. Completed SGC: Mined land reciamauon reauuc Mayflower Mayflower Mill Re-contour inactive tailings Sunnyside 1991-1992 $1,755,000 loading of metals and erosion Gold Mill - complex near ponds and cap. transport of tailings 625,000 yards of tailings and Coip. Tailings Boulder Creek Ponds #1, #2 and Animas overburden moved. SGC: $911,000 Mined land reclamation ana reaute Fill mine subsidence, remove Completed Sunnyside Lake Emma Sunnyside Basin loading o f metals 240,000 yards mine waste and 1991-1993 Gold Sunnyside headwaters of re-contour disturbances. Corp. Basin Mined land reclamation ana reauce Remove 90,000 yards of waste Completed SGC: $766,500 Sunnyside American Gladstone on loading o f metals and erosion dump and underlying historic 1995 Gold Tunnel waste bank o f S. Fork transport of tailings tailings Corp. Completed SGC: $843,000 Reduce loading ot metals ana Eureka On banks and In Remove 112,000 yards of Sunnyside 1996 erosion transport of tailings Gold Townsite floodplain of tailings Corp. Reduce loading to Animas Kiver io Divert and treat Cement Creek 8/96-5/99, SGC: $901,000 Sunnyside Gladstone Cement Creek at offset any short term impacts of to mitigate any short term 11/99- Gold Gladstone reclamation of other sites. impacts of reclamation projects 12/99 Corp. Reduce loading ot m eta is ana Remove 5700 yards o f tailings Completed SGC: $32,500 Sunnyside Boulder Flood plain of erosion transport of tailings 1997 Gold Creek Boulder Cr. and Corp. the Animas River Restore hydrologie regime and Bulkhead seal to stop deep Completed SGC: $85,400 Sunnyside Ransom adit Eureka townsite reduce rate of ore oxidation by mine drainage and reclaim 1997 Gold above old mill placing mine workings under water Corp. foundation portal to reduce metal loading. Reduce exposure to water xo reuuL-c Bulkhead seals to stop deep Completed SGC: $151,000 Sunnyside Gold Prince Headwaters of metal loading mine drainage. Consolidate 1996-1997 Gold mine waste Placer Gulch mine waste and tailings (moved Corp. and tailings 6000 yards) and construct upland diversions Oï - II] Wing Wing Mining Co Mining Silver Silver Corp Mines King Gold Gold Corp. Sunnyside Corp. Gold Sunnyside Corp. Gold Sunnyside Corp. Gold Sunnyside Goid Corp. Sunnyside Corp. Gold Sunnyside Corp. Gold Sunnyside Silver Wing Silver Gold King Gold hydraulic seal project seal Mine groundwater diversion Sunnyside Sunnyside TP TP modification drainage TP #4 TP Hydrological Control Upland Mayflower Mine Sunnyside West tailings West Pride o f f o the Pride Koehler Longfellow- #4 upland above Eureka above about 1.5 mile mile 1.5 about Animas river, river, Animas Creek f Cement o Fork N. Gladstone, near Silveiton near Sunnyside Mine Sunnyside Tailings Pond #4 #4 Pond Tailings near Silveiton Silveiton near Up-gradient from from Up-gradient and Animas R. Animas and between Hwy. Hwy. between ditch Drainage Silveiton near area #1 Pond Tailings and Mill Mayflower 110 and TP #4 #4 TP and 110 Lake Emma Area Emma Lake River Animas confluence near Sunnyside Mine Mine Sunnyside with Creek f Cunningham o Howards ville Howards Mountain Pass Mountain Red of top near Mineral Creek Creek Mineral of Headwaters controls Collect AMD, hydrological hydrological AMD, Collect workings and mine waste mine and workings Hydrologie controls for for controls Hydrologie from adits adits from drainage eliminate and mining regime to approximate pre approximate to regime hydrologie restore to Mine side Sunny in placement Bulkhead around tailings impoundment tailings around tailings material tailings Capture groundwater and divert divert and groundwater Capture prevent infiltration through through infiltration prevent capture surface runoff and runoff surface capture to ditch diversion lined Install and TP #1 facilities #1 TP and surface up-gradient o f the mill mill f the o up-gradient surface sub going were that drainages provide increased alkalinity and and alkalinity increased provide Capture and divert three upland upland three divert and Capture conditions improve initial mine pool pool mine initial improve to pool Mine Sunnyside the into tailings Inject 652 tons o f hydrated lime lime f hydrated o tons 652 Inject treatment o f Koehler drainage f Koehler o treatment Remove 84,000 yards of of yards 84,000 Remove Feasibility study o f wetland f wetland o study Feasibility diversions. drainages.Construct dump and cap. Capture adit adit Capture cap. and dump Longfellow and dump Tunnel Junction consolidate yards), Remove Koehler dump (32,100 (32,100 dump Koehler Remove (6 bulkheads) 1995 Completed 1998 Completed 1992-1996 1999 1993-1995, Completed 1999 Completed 1998-1999 Completed 1996-1997 Completed 1997 Completed 1996-1997 $7,000 Silver Wing Silver Gold King: King: Gold $117,300 $2,346,000 SGC: G: $409,000 SGC: SGC: $72,000 SGC: G: $186,000 SGC: SGC: $313,000 SGC: $14,000 TUSCO: SGC: $490,500 SGC: SGC: $580,000 SGC: metals loading metals reduce dump, from AMD Remove perpetual water treatment water perpetual workings and eliminate need for for need eliminate and workings of Cement Creek Cement of Fork North to loading metal Reduce groundwater movement around mine mine around movement groundwater restore oxidation, reduce potential for metal loading metal for potential Place mine workings under water to to water under workings mine Place groundwater with tailings and reduce reduce and tailings with groundwater Minimize potential for contact of of contact for potential Minimize potential for metal loading metal for potential runoff with tailings and reduce reduce and tailings with runoff of contact for potential Minimize potential for metal loading metal for potential runoff with tailings and reduce reduce and tailings with runoff of contact for potential Minimize to stop mine drainage mine stop to bulkheading through restored is table Improve initial conditions as water water as conditions initial Improve of tailings by erosion by of tailings Reduce metal loading and transport transport and loading metal Reduce transport of mine waste mine of transport Reduce metal loading and erosion erosion and loading metal Reduce » iuiws wj m aiuiim uie 10 ement Creek Reduce metal loadingto Animas River Creek Reduce metalloading to Mineral Reduce surface water leacnmg oi River toxic meiais Reduce metal loadingto Animas Collect AMD tor possioie iredunttLu., remove surface waterfrom site CollectAMD for later ucauueiit proiect development Reduce surfacewater leacnmg oi C toxic metals Focused on reductions oriron waste RaisepH from draining aoit, icuuccmetal loading from adits and mine Riverby reducing infiltration ofwater into old mineworkings Reducemetals loading River Cadmium, Copper, Iron, Lead, Manganese, andZinc Reduce loading ot meiaisto Reduce loading ot meiais espccumy River. Reduce metalloading to the Animas 10,000 BLM: $300,000 BLM: $70,000 BLM: $87,000 BLM: $290,000 BLM: $17,800 Surface Mining: $ BLM: $36,000 Office of Salem: $6,700 $10,050 319 Funds: MRRC: 38,500 $58,000 319 Funds: $44,600 ARSG Match: $66,900 319 Funds: ARSG Match: $52,300 319 Funds: $78,500 $62,800 $72,000 ARSG match: 319 Funds: SilverWing: $144,000 $216,000 319 Funds: 2 0 0 0 1998-1999 2 0 0 0 1998-1999 1999 1998-1999 1998 1999 1995 season 2000 1999 season 2000 completed Phase -1 1999-2000 consolidationand capping. avalanchepath. Removal oftailings from flood plainto Mayday dump for AMD collection anddiversion, move waste rockfrom ofmine waste pile Hydrological controls, captop AMD collection andpassive wetlandtreatment controls AMD collection, hydrological Mine drainage collection and diversion Waste consolidation & hydrological controls Settling ponds for mine drainage Anoxicdrain, settlingpond, waste consolidation, bulkhead into San Antonio Mine Workings Reduce flows from Kohler Tunnelby reducing infiltration Complete removal ofwaste rock from stream channel bioreactor ofwaste rock from stream channel Removal of1,900 cubicyards Anoxic Drain, settlingpond, Silverton Animas near Forkof Mineral LowerMiddle Cement Creek Animas near Prospect Gulch ProspectGulch ProspectGulch Cement Creek NorthFork of Placer Gulch KohlerTunnel Eastof Red Mineral Creek Mineral Creek East oRed f Headwaters of above Eureka Headwaters of about 1.5 miles Animas River, 1 P a r t ? Tailings Lackawanna Bonner Mayday Forest Queen LarkMine Joe &John Queen Galena Tunnel Mammoth Sunbank Group IT IT Carbon Lakes Mine Waste Phase Carbon Lakes Mine Waste Phase Dump Carbon Lakes Mine SilverWing U.S. BLM U.S. BLM U.S. BLM U.S.BLM U.S.BLM Surface U.S.BLM Mining Officeof Minerals Salem Recovery Remedial Mining (ARSG) San Juan RC&D (ARSG) RC&D San Juan San Juan RC&D (ARSG) Mining Co Silver Wing Ill - 11 REFERENCES: Buxton, Herbert T. “A Watershed Approach to Contamination of Abandoned Mined Lands: The USGS Abandoned Mined Land Initiative,” U.S. Geological Survey Toxic Substances Hydrology Program- Proceedings o f the Technical Meeting, Charleston, South Carolina, March 8-12, 1999, Water Resources investigations Report 99-4018A. Church, S.E., B.A. Kimball, D.L. Fey, DA. Ferdered, T.J. Yager, and R.B. Vaughn, Source, Transport, and Partioning o f Metals between Water; Colloids, and Bed Sediments o f the Animas River, Colorado, U.S. Geological Survey Open File Report 97-151, 1997. Church, S.E., D.L. Fey, and Robert Blair, “Pre-Mining Bed Sediment Geochemical Baseline in the Animas River/’ Proceedings of ICARD Conference, May 2000. Colorado Water Quality Control Division, Exhibit 3 - Upper Animas Water Quality Classification and Standards Proposal, July 1994, presented to the Colorado Water Quality Control Commission. Herron, Jim, Bruce Stover, Paul Krabacher, and Dave Bucknam, Mineral Creek Feasibility Investigations Report, Colo. Division of Minerals and Geology, Feb. 1997. Herron, Jim, Bruce Stover, and Paul Krabacher, Cement Creek Reclamation Feasibility Report, Colo. Division o f Minerals and Geology, Sept. 1998. Herron, Jim, Bruce Stover, and Paul Krabacher, Reclamation Feasibility Report Animas River above Eureka, Colo. Division of Minerals and Geology, Oct. 1999. Herron, Jim, Bruce Stover, and Paul Krabacher, Reclamation Feasibility Report Animas River below Eureka, Colo. Division of Minerals and Geology, Nov. 2000. Hite, Barbara J., Abandoned Mine Land Inventory o f BIM Administered Land in Upper Animas River Watershed, Colorado, Colorado State BLM Office, Denver, CO,, Feb. 1995. Farrell Price, Camille, Site Inspection, Analytical Results Report. Upper Animas Watershed (CERCLIS //)# C00001411347) San Juan County, Colorado, Colo. Dept, of Public Health and Environment, Div. of Hazardous Materials and Waste Management, Mar. 1999. Kimball, Bryant A., Robert L. Runkel, Kenneth E. Bencala, and Katherine Walton-Day, “Use of Tracer- Injection and Synoptic-Sampling Studies to Quantify Effects of Metal Loading from Mine Drainage,” US. Geological Survey Toxic Substances Hydrology Program- Proceedings o f the Technical Meeting, Charleston, South Carolina, March 8-12, 1999, Water Resources Investigations Report 99-4018A. Leib, Ken, USGS, Durango, unpublished spreadsheet describing drainage areas for different sampling points in the Upper Animas Basin, Mar. 2000. Lovekin, Jonthan R , Michael J Satre, William M. Sheriff, Matthew A. Sares, USFS-Abandoned Mine Land Inventory Project, Final Summary Report, Colorado Geological Survey, April 1997. Medine, Allen J., Water Quality Assessment, Animas River Basin, prepared for U.S. Environmental Protection Agency, Region VIII, Denver CO., Feb. 2, 1990. Robinson, Rob, U.S. Bureau of Land Management, Denver office, unpublished spreadsheet describing expenditures in the Upper Animas Basin, Jan. 2000. Periodically updated. Western Aquatics, Inc., Use Attainability Analysis o f the Upper Animas River, prepared for Standard Metals Corporation, Silverton CO., Jan. 22,1985. Wright, Winfield G., Natural and Mining-Related Sources o f Dissolved Minerals during Low Flow in the Upper Animas River Basin, Southwestern Colorado, Fact Sheet FS-148-97, Oct. 1997, U.S. Geological Survey, Durango, CO. CHAPTER IV - AREA OVERVIEW PHYSICAL DESCRIPTION The Animas River begins its 110 mile journey south into New Mexico as a little babbling brook well above 12 000 feet in the heart of the San Juan Mountains of southwestern Colorado, arows quickly as alpine creeks tend to do as it slices through high peaks and historical mining camps for fifteen miles to the town of Silverton. Below Silverton, the river enters a deep, 2 mile canyon accessible only by foot, horseback, or narrow gauge team. The flow of the river almost doubles in size as tributaries plunge down from the surrounding Needle Mountains T river itself drops 2,400 feet in elevation through this stretch. Although it sees little traffic because of the remoteness and difficulty of the trip, this part of river is considered one of the premier whitewater runs in the country. It is also the location of one of the country s most scenic and historical train rides. At Baker’s Bridge, the river exits the canyon into a broad, low-gradient valley north of Durango. In the upper part of the valley, the river bottom is heavily mined for gravel. Below Trimble Lane the river becomes totally placid, meandering lazily through a wide grassy floodplam, principally used for hay and pasture, but now quickly filling with development. As the river reaches the terminal moraines left by an ancient glacier, its pace quickens as it enters the City ot Durango. The stretch of river through the town is one of the most heavily rafted in the state. Approximately 32,000 commercial passengers float through this section annually along wit thousands of private boaters. Overall, the Animas River ranks tied for third as the most heavily boated river in the state. Below Durango the river continues to move quickly through hilly pinon-jumper country within the exterior boundaries of the Southern Ute Indian Reservation. After twenty miles, «reaches New Mexico and again slowly meanders through irrigated farmland giving way to desert at the town of Aztec. From Aztec, the river flows another ten miles through a populated area to Farmington where it joins the San Juan River. The Upper Animas Basin Most of the metal loading to the Animas River comes from the Upper Animas River Basin. ('Church et a l 1997) For the purposes of this study, the Upper Animas Basin is defined as the Animas River and all its tributaries above the gage station at A72 which lies Just bdow Silverton The Upper Animas Basin ranges in elevation from 9,200 feet to almost 14,000 feet above sea level and covers 146 square miles of spruce-fir, sub-alpine and alpine environments. All of the Upper Animas Basin lies within San Juan County. The Upper Animas Basin is divided into three sub-basins consisting of Mineral Creek Cement Creek and the Upper Animas River. All three basins have similar elevations and are all oriented in a general north to south direction. The mainstems of Cement Creek, Mineral Creek above South Mineral Creek, and the Animas above Eureka Gulch have steep channel gradients n excess of 4 percent. Gradients of most tributaries are even steeper, owing to the extremely mgged relief of the basin. The steep gradients produce high stream velocities and few opportunities to store fine sediment in the channels. The Animas River between Eureka Gulch and Mineral Creek and Mineral Creek below Smith Mmeral flow across glacial till and have lesser gradients in those reaches The^confine! sedTent Tl^lareesTofTh6 deP° S‘tS “ ***** °PP0rtUnity t0 meander a"d seasonally store T n \ these areas 1S known as Baker,s park, the flat plain where Silverton is located. Cement Creek and Mineral Creek join the Animas River at the lower end of the Park. A dm « pr Uppe[. An™as Basin Iies within a collapsed volcanic caldera. Mineral Creek and the p',™ 'Vfr follow ^ n "8 fractures that outline the structural boundary of the Silverton Caldera while Cement Creek is entirely within the Caldera. The collapsed volcano and the The rrf'12 events followm§ mineralized the area which eventually attracted miners to the region 6"06 Appendix 7 A) oroughthH rdescription °f oft ,these metalS geologic affeCt'n* processes, Water quality see Chapter inrteei VII r and as H ydrology Most precipitation occurs in the form of snow which can occur any day of the vear At hioh ron“ L o Ju!vSt r mT nt ^ Cover ^ be» n in °ctober and substantial coverage may continue into July. Annual snowfall can range from 2 0 0 to 300 inches depending on vear and n i T , 1“ !. ^ " Wlnter snow deP*hs may be fiftcen feet. Because o f weather patterns the snow K u T r of s"ve" " *"& ~ “ ”™ ' * » ” " A ’ Sllverton 18 home to an avalanche forecasting center run bv ~ i i . * S 2 ,:LTr po“'ion “ of with sediment washed from the steep surrounding landscape. The U.S. Geological Survey has gaged streamflow on the Animas River at the 13th Street HriH.m in Silverton (A-68 , Cement Creek near the Silverton town nark rc S r u f Silverton Visitors Center (M-34), and the Animas «»“a« yi * c™r„°“= Silverton orwr^ on the Upper ^ Animas River between 1936 and 1982 A reservoir was at one time planned for this site as part of the Animas-La Plata wate nroiP,? Average annual runoff for the three sub-basins above A-72 is approximately 29 inches per year, ' Flow (cfs) Figure 4.1 Animas River Flow at Howardsville Gauge Howardsville at Flow River Animas 4.1 Figure September 1972 -September 1982 -September 1972 September Date 9/30/82 Correlations of daily discharge between A-68, M-34, and C-48 and A-72 indicate that discharge is proportional to the drainage area above the gage with a few exceptions. Approximately two percent of the watershed is in between the upper three gages and A-72, however differences in measured streamflow between A-68, C-48, and M-34 and A-72 consistently suggest this area produces 9 percent to 14 percent of the discharge. The higher percentage is associated with low flows. This is probably due to surface water that infiltrates the glacial till in this area, prior to reaching the gages. This water is slowly released throughout the year. Correlations also show that Cement Creek contributes about 20 percent of the discharge at A-72 at lower flows compared to its watershed area of 13.5 percent. At moderate to high flows the contribution of discharge from Cement Creek approximates the percentage of watershed area. The gaged discharge for Mineral Creek is consistently about 30 percent for all flow ranges which is somewhat less than its proportional watershed area (36%). Table 4.1 Selected Watershed Characteristics Gage Area Area Annual High Mean Annual Sub-Area Elev. (Sq. miles) (% of A-72) Flow (cfs) Flow (cfs) Animas @ 9617 55.9 38.3 818 102 Howardsville Animas (A-68) 9290 70.6 48.3 1040 112 Cement (CC-48) 9380 20.1 13.7 274 35 Mineral (M-34) 9246 52.5 36.0 856 97 Other na 3.1 2.0 na na Animas (A-72) 9200 146.0 100.0 2210 260 Ecology The Upper Animas Basin is very similar to other alpine environments in the San Juans. Late summer rains feed a thick undergrowth in aspen and spruce-fir forests. The lush tundra slopes are grazed by thousands of domestic sheep after the snow is gone. Cattle are not currently grazed in the basin but have been historically. The Basin is home to elk, mule deer, black bear, mountain lion, coyote, marmot, and an occasional moose and recently introduced lynx. Stream riparian vegetation consists of a few individual narrow leaf cottonwoods plus one small stand at the mouth of Minnie Gulch. Photographs taken in the late 19th Century by William Jackson indicates that streams were heavily covered by willow thickets. Many stream segments are now devoid of willows, likely as a result of historical grazing practices. Recently willow recovery appears to be progressing since cattle are no longer grazed below timberline and sheep grazing allotments have been severely reduced. Erosion and sediment loads may be somewhat reduced now but streambeds were heavily impacted by sediment deposition in the past. For example, Vincent (1999) found that rate of sediment deposition was 50 to 500 times greater from 1880 to 1918 and 200 to 4,700 times greater from 1921 tol930 than the natural rate m the flood plain below Eureka. Vincent attributes the high aggradation rate to mine waste and tailings dumped into the river although extensive overgrazing near the turn of the century may have been a contributing factor as well. In any case, having been covered by finer sediments boulders are seldom seen in the lower valleys of South Mineral Creek, lower Mineral Creek, and the Animas River between Eureka and Silverton. These conditions do not exclude fish but quality habitat is minimal. In the Animas canyon below Silverton the gradient of the river channel is two to three percent and is dominated by large boulders and cobble. Segment 4a is a narrow channel confined by rock cliffs on one side and the railroad grade on the other. Little vegetative cover exists but below Elk Park (Segment 4b) the valley widens and a very healthy riparian zone borders the river. Wildlife abounds in this remote section of nearly pristine riparian element. Mixed cottonwood and spruce overstory have thick shrub understories of alder, Rocky Mountain maple, river birch, willow, twinberry, and dogwood. The Animas valley below Baker s bridge was dominated by large gallery forests of narrowleaf cottonwood and box elder until the 1970 s when development lead to their demise. Little cover remains and the once meandering channel has been lowered within its banks through years of gravel removal. (Chapter VI and accompanying appendices provide more detailed information on specific biological, chemical, and physical conditions affecting aquatic life throughout the Animas watershed.) MODERN DAY SETTLEMENT Although Spanish prospectors may have visited the region a century or two before, prospecting in the Upper Animas Basin is recorded to have started in 1860, when Charles Baker and his party visited the area. Baker sent out glowing reports of panning for gold, spurring. others to follow his lead In actuality, little was found and with the beginning of the Civil War, prospecting discontinued. Mining didn’t really begin until 1870. Then the ore strikes were rich enough to attract hordes of potential miners. There was enough activity that the first mill arrived in 1872. The miners were trespassing, but it didn’t stop them. The San Juan Mountains were located in the middle of the Ute Indian Territory, and Utes loudly protested the presence of the miners^ However, instead of evicting them, the federal government “negotiated” the Brunot Treaty of 1873 in which the Utes ceded the San Juans to the United States. By 1873 more than 1,500 claims had been staked in the area, and by the next year the town of Silverton was platted. Rough roads were constructed for wagons to Lake City, Del Norte and Ouray, but shipping ore by wagon or pack train was very expensive. Mining didn t really take off until 1882 the year that tracks for a narrow gauge railroad snaked their way up the Animas Canyon from Durango to Silverton. The railroad provided a more economical way to transport supplies into Silverton and ore out to Durango. The train became the economic lifeline for Silverton, a role it still plays today. Today, the railroad is the longest continually run narrow gauge in the country. With the opening of what is now called the Durango-Silverton Narrow Gauge Railroad (previously the Denver and Rio Grande Railroad), development grew at a furious pace. Mines opened up throughout the Basin. By 1888, a railroad had been completed over Red Mountain ! Sn°JS!7 e the Red Mountain Dlstrict encompassing the upper reaches of both Mineral Creek and Red Mountain Creek. A railroad was constructed in the Upper Animas drainage reaching Eureka in 1895 and Animas Forks by 1904. In 1899, the owners of the Gold King constructed a railroad up Cement Creek to Gladstone to transport ore. Mining also meant milling and by the turn ot the century, over thirty mills and two smelters had been constructed in the Basin. In terms of population and the number of working mines, mining peaked around 1900-1908 Most of Silverton’s public buildings were constructed during this time (Gregory and Smith^ U A \ ^ j 168 opened and shut depending on metal prices, but by the 1920’s most of the mines had shut down for good. In fact, from the early 1930’s to 1991, when the last mine, the Sunnyside, closed down, 90 percent of the ore production had come from only two mines However, with modern technology, these two mines were able to annually produce as much ore as was annually produced during the heydays of mining (Jones, 2000. See Appendix 7C for a more detailed description on mining, milling, and their environmental impacts in the Basin.) Today Silverton’s economy is based on summer and fall tourism. Around 200,000 passengers ride the rails of the narrow gauge each year from Durango to Silverton. Eighty-year-old coal- tired stream engines grunt up the grade, hugging canyon walls overlooking the Animas Upon reaching Silverton, they disgorge their passengers who visit historic sites, shop, and eat lunch before re-boarding the tram for the return trip. Other tourists come to stay for days, filling the hotels or campgrounds while they explore the many jeep roads, historical mine sites and natural features. The attraction of Silverton is the beauty of the scenery and the chance to explore the rich history of mining. Silverton has a very active historical society and has been quite adept at securing grants for historical preservation. In recent years the society, in partnership with agencies like the U.S. Bureau of Land Management, have restored or stabilized structures in Animas Forks and the famous Old One Hundred Boarding House. Local residents want to ensure that mine remediation does not destroy part of their histoiy. ARSG works closely with the historical society and the San Juan County Board of County Commissioners in designing remediation projects that minimize impacts to these cultural features. San Juan County’s year round population is much diminished from the mining days but remains stabilized at around 320. Perhaps all but a dozen live in Silverton. They eke out a living through hard work in the summer and by finding whatever odd jobs are available in winter. Hardly any of the year round residents own mine claims. Mine owners are scattered around the country. Very few of the mine sites are owned by large corporations. Most are owned by small amihes or individuals who inherited the claims and may never have even seen them Their knowledge of how their sites may affect water quality is often minimal. And since few current mine site owners profited directly from the mining of these sites, their complete understanding of their potential liabilities and their financial ability to fund remediation are often lacking Remedation planning must take these people and the natural limitations of the environment into REFERENCES Brown Robert L., An Empire o f Silver, An Illustrated History, Sundance Publications, LTD., Denver, ’ CO, 1984, ISBN 0-913582-36-0. Church SE BA Kimball D.L. Fey, D. A. Ferdered, T.J. Yager, and R.B. Vaughn Source Transport, andPartionZ of Metals between Water, Colloids, and Bed Sediments of the An,mas River, Colorado, U.S. Geological Survey Open File Report 97-151, 1997. Gregory Marvin and P. David Smith, The Million Dollar Highway, Colorado's Most Spectacular Seventy S Mfev, Westem Reflections, Ouray, CO, 1997, ISBN 1-890437-01-8. Jones, William R„ History of Mining & Milling Practices ¿.Productionin the Upper Animas River Drainage 1871 -1 9 9 1 , Dec. 2000, unpublished document m Appendix 7L. Vincent KR SB Church and D.L. Fey, “Geomorphological Context of Metal-Laden Sediments in the M im ;S L e r K l a i n , Colorado,” I7.fi Geological Survey Tof icSubstances Hydraogy P r o g r a m - Proceedings o f the Technical Meeting, Charleston, South Carolina, March 8-12, 1999, Water Resources Investigations Report 99-4018A. CHAPTER V: EXISTING USES Water quality classifications and standards are used to protect existing or practicably achievable uses and to establish criteria that will meet the fishable/swimmable goals of the Clean Water Act. Colorado’s approach is to establish use classifications and assign water quality standards, usually numeric criteria, to protect those uses. Numeric criteria protect the most restrictive use. For example, standards for cadmium, copper, lead, manganese, and zinc are required for waters supporting both aquatic life and water supply uses. The aquatic life s ta n d a r d s are more restrictive for all these metals except manganese. If these two uses are present, the aquatic life standards would be assigned for cadmium, copper, lead and zinc, but the water supply standard would be assigned for manganese. The use classifications presently assigned to surface waters in the Upper Animas watershed are summarized in Table 5.1. The bases for assigning them are discussed in this chapter. Table 5.1 Existing Use Classifications in the Upper Animas Basin------7 —,------Segment Description Aquatic Aquatic Recreation Recreation Water Agriculture r I 2 I______2 Supply X X 1 Weminuche X X Wilderness X X 2 Animas above Maggie Gulch X X 3a Animas above X Cement Creek X 3b Animas above Mineral Creek X 4a Animas above * X Elk Creek X X X 4b Animas above X Junction Ck X X X 5a Animas above X So. Ute Line X X X 5b Animas above X New Mexico X X X 6 Upper Animas X tributaries X X 7 Cement Creek X X 8 Mineral above South Mineral X X X 9a South Mineral X X X 9b Mineral below X South Mineral X X X 12a Tributaries X To 4a and 4b X _____X Cascade Creek X Aquatic Life Aquatic life is classified as warm or cold and as class 1 or class 2. The distinction between warm and cold is whether or not the water temperature is suitable for a cold water fishery (trout) or for warm water species. Surface waters in the Upper Animas Basin are classified cold water. Aquatic life class 1 streams have the physical characteristics (i.e. substrate, cover, and flow conditions) to support a wide variety of cold water biota. Suitability of habitat and water quality distinguishes class 1 from class 2 streams. Streams with insufficient flow, habitat, or water quality that are either naturally impaired or irreparably impaired by human-induced causes may be classified aquatic life 2. Class 2 streams do not support a wide variety of cold water biota. Water quality investigations of the Upper Animas Basin between 1991 and 1994 found that segments 1, 3a, 4b, 5a, 5b, 6, 9a, 9b, and 12a have the capability to fully support aquatic life class 1 uses (WQCD, 1994). The 1994 water quality standards hearing and EPA’s letter of April 1998 concluded that segments 2, 3b, 1, and 8 do not support aquatic biota and are irreparably incapable of supporting minimal forms of aquatic biota. These segments have no aquatic life classification. Recreation Recreation classifications were modified by the Colorado WQCC in 2000. Recreation class 1, used for activities in or on the water if the ingestion of small quantities of water is likely to occur, was separated into la and lb in order to comply with the federal Clean Water Act. Class la waters meet the swimmable” goal of the federal act and are applied to waters where primary contact uses have been documented or are presumed to be present. Class lb is indicates waters where no use attainability has been performed demonstrating that class 2 is appropriate. Class 2 is applied where there is minimal chance that a recreation class 1 activity could be supported. Water quality standards for la, lb, and 2 class recreation waters are distinguished by the standard for E. Coli and fecal coliform. Recreation class 2 waters have a fecal coliform standard of 2000/100ml whereas class la waters have a standard of 200/100ml and 126/100ml fecal coliform and E coli, respectively. Class lb waters have fecal coliform and E. coli standards of 325/100 and 205/100 ml, respectively. A recreation la classification is intended to affect only the use classification and water quality standards of a segment. It does not imply public or recreational access to waters with restricted access within a segment. Water supply Waters with water supply classification are suitable for potable water after receiving standard treatment, filtration, and disinfection. The water supply classification is applied if the segment is a source of domestic supply or if the quality is suitable for that use. The WQCC modified standards applied to segments with the water supply classification in 2000. No water supply V - 2 standards are applied for iron, manganese, or sulfate unless the segment is in actual use as a water supply. Standards for these constituents are either the ambient concentration as of January 1 2000 or the previous secondary standards, whichever is less stringent, unless the WQCC determines, as the result of a site-specific hearing, that different standards are appropriate. Agriculture The agricultural classification is used for waters that are diverted for irrigation or that may be used for watering livestock. Sheep graze the headwaters of the Ammas, Mineral, and Cement Creeks in the late summer and early fall. This is the only agricultural use of water in the upper basin. Irrigation and stock watering are common uses in the lower basin. Although agricultural uses are recognized in the classifications, standards are usually applied only if there are specific agricultural activities such as irrigation, USE CLASSIFICATIONS FOR INDIVIDUAL SEGMENTS Segment 1 Streams in segment 1 are all of the pristine headwater streams, lakes, and wetlands located within the Weminuche Wilderness area. They have not been affected by mining. These waters have the most restrictive use classifications, which are aquatic life (cold) class 1, recreation class la water supply, and agriculture. These streams are subject to anti-degradation review procedures of Section 31.8; 5CCR 1002-31, The Basic S ta n d a rd s and Methodologies. Segment 2 Segment 2 is the main stem and all tributaries and wetlands to the Animas River from the outlet of Denver Lake to immediately above the confluence oi Maggie Gulch, excluding waters m segment 1. None of the waters in segment 1, the Weminuche Wilderness, are contiguous with segment 2 The segment is classified recreation 2 and agriculture. The waters of the segment meet the WQCC’s criteria for recreation la. The agricultural classification was assigned because sheep graze the watershed and the livestock may be watered from the streams. Water quality investigations by the WQCD (1994) found that the aquatic life use is not present and is not likely to be present within a twenty-year period owing to irreversible water quality conditions resulting from both natural and human-induced conditions. The concentrations of several metals exceed water supply criteria in some of the tributaries to the Animas in segment . Investigations by the CDPHE (1997) did not identify any domestic uses of water in the segment. Segment 3a This segment is the main stem of the Animas River and associated wetlands from Maggie Gulch to Cement Creek. The segment is classified for aquatic life class I, recreation 2, and agriculture. The segment is classified aquatic life 1 because investigations by the WQCD (1994) found a sustainable population of brook trout in this reach of the Animas. Currently there is some boating use of the segment during the period of high water. The waters of the segment meet the WQCC’s criteria for recreation la. Investigations by the CDPHE (1997) did not identify any domestic uses of water in the segment, and several constituents exceed the water supply criteria. The agricultural classification was assigned because sheep graze the watershed, and livestock may be watered from the river. Segment 3b This segment is the main stem and associated wetlands of the Animas from Cement Creek to Mineral Creek. The segment is classified recreation 2. There now exists some boating use of the segment during the period of high water. The waters of the segment meet the WQCC’s criteria for recreation la. The segment is not classified for aquatic life. The joining of Cement Creek and the Animas River drastically alters the water chemistry of this segment of the Animas. Water quality investigations by the WQCD (1994) found that the aquatic life use is not present and is not likely to be present within a twenty-year period owing to irreversible water quality conditions resulting from both natural and human-induced conditions. Investigations by the CDPHE (1997) did not identify any domestic uses of water in the segment. The agricultural classification was not assigned because the sheep grazing allotments are outside of the segment. Segment 4a This segment is the main stem of the Animas River and associated wetlands from the confluence with Mineral Creek to the confluence with Elk Creek in the Animas River canyon. The segment is classified aquatic 2, and recreation 1. Segment 4a is classified aquatic life 2 owing to high concentrations of metals. The WQCC adopted class 1 as a goal for this segment if sufficient improvement in water quality can be achieved. The main purpose of this UAA is to determine if the water quality classifications and standards adopted in 1995 and disapproved by the EPA in 1998 will be achieved if human-induced sources of metal loading are remediated. The recreation I classification applies because the segment is used for white water boating during periods of high flow (WQCD, 1994). The waters of the segment meet the WQCC’s criteria for recreation la. There are no identified domestic uses of water in the segment. The agricultural classification was not assigned because the sheep grazing allotments are outside of the segment. Moreover, most of this short reach of the river is within a canyon and is inaccessible to livestock. This segment is the main stem of the Animas River, including associated wetlands, from the confluence with Elk Creek to Junction Creek near downtown Durango. The segment from Elk Creek to Baker’s Bridge, about 27 miles downstream, is within a canyon that is accessible only by boat, the narrow gauge railroad, or primitive travel. The Animas River exits the canyon below Baker’s Bridge and enters a broad, low gradient glacial valley. The natural and cultural features of the surrounding land use change from a primitive area to one of intensive agriculture and urbanization. The segment is classified aquatic 1, recreation 1, water supply, and agriculture. The segment is classified aquatic life 1 because investigations by the WQCD (1994) found a sustainable trout population in this reach. The waters of the segment meet the WQCC’s criteria for recreation la. The waters are used for white water boating and are suitable for activities that include full body contact WQCD (1994). Domestic uses of water in the segment are present downstream from Baker’s Bridge. The agricultural classification was assigned because the river is used for irrigation and livestock may be watered from it downstream from Baker’s Bridge. Segment 6 This segment includes the main stems, tributaries, lakes, and wetlands of Cinnamon Creek, Grouse Creek, Picayne Gulch, Minnie Gulch, Maggie Gulch, Cunningham Creek, Boulder Creek, Whitehead Gulch, and Molas Creek from their sources to the Animas River. The main stem of the Animas from its source to the outlet of Denver Lake is also included in the segment. Portions of some of these streams lie within segment 1, the Weminuche Wilderness. Most of the tributaries in the segment are within the Silverton caldera, however a few, including Whitehead Guich and Moias Creek, are outside of the caldera region. Some tributaries to the Animas above Elk Creek are not classified because they are not included in any segments The segment is classified aquatic 1, recreation 2, water supply, and agriculture. The aquatic 1 classification was applied because several streams (e.g. Cunningham Creek) support aquatic life and all have low concentrations of metals. The waters of the segment meet the WQCC’s criteria for recreation la. The water supply classification was applied because the Silverton uses Boulder and Bear Creeks as their municipal source and all water supply criteria are met. The agricultural classification was applied because domestic sheep graze portions of the segment. This segment includes all of the surface water in the Cement Creek watershed. The segment is classified for recreation 2 and agriculture. Aquatic life and water supply classifications are not supported in segment 7 . Water quality investigations by the WQCD (1994) found that aquatic life use is not present and is not likely to be present within a twenty-year period owing to irreversible water quality conditions resulting from both natural and human-induced conditions. The concentrations of several metals exceed water supply criteria in this tributary to the Animas, investigations by the CDPHE (1997) identified several private domestic users of water in the segment. The CDPHE notified those mdividuals that they were possibly using water where drinking water standards were not being met. I hey also made appropriate recommendations for treatment before use. (CDPHE, 1997). The waters of the segment meet the WQCC’s criteria for recreation la. The agricultural classification was assigned because sheep graze the watershed and the livestock may be watered trom the streams. Segment 8 This segment is the main stem of Mineral Creek, including associated wetlands, from the source to the confluence with South Mineral Creek. The segment is classified for recreation 2 and agriculture. Aquatic life and water supply classifications are not supported in segment 8. Water quality investigations by the WQCD (1994) found that the aquatic life use is no? present and is not likely ■° Present within a twenty-year period owing to irreversible water quality conditions resulting trom both natural and human-induced conditions. The concentrations of several metals exceed water supply criteria in this tributary of the Animas. Investigations by the CDPHE (1997) identified several private domestic users of water in the segment. The CDPHE notified those individuals that they were possibly using water where drinking water standards were not being met. 1 hey also made appropriate recommendations for treatment before use. The waters of the segment meet the WQCC’s criteria for recreation la. The agricultural classification was assigned because sheep graze the watershed and the livestock may be watered from the streams. Segment 9b Iohn fl,L T enU% thefl,T ,in T . 0f, Mineral Creek’ includ,n« assoc>ated wetlands, from the confluence with South Mineral Creek to the Animas River. It is presently classified aquatic 1 recreation 2, and agriculture. M ’ Prior to 1994 the segment was thought to not support aquatic life. Water quality investigations of the Upper Animas Basm between 1991 and 1994 found that with remediation of human- induced sources of copper and zinc that it had the capability to fully support aquatic life class 1 uses (WQCD, 1994). The segment is classified for recreation 2 and agriculture. The waters of the segment meet the WQCC’s criteria for recreation la. The agricultural classification was assigned because sheep graze the watershed and the livestock may be watered from the streams. Investigations by the CDPHE (1997) did not identify any domestic uses of water in the segment. Summary The classification listed above were applied in 1994. Since then, a tremendous amount of additional data has been collected in these segments. This data, presented in the following chapters, has led to several proposed changes in segment descriptions and use classifications described in Chapter XII. REFERENCES Colorado Water Quality Control Commission. 1999. "The Basic Standards and Methodologies for Surface Water" 5CCR 1002-31. CDPHE. Farrell Camille M.S. 1997 Comprehensive Analytical Resuits Report Cement Creek ’ watershed, San Juan County, Colorado. Colorado Division of Hazardous Materials and Waste Management; CDPHE. Farrell Camille M. S. 1997. Site inspection sampling activities report Upper Animas watershed, ’ San Juan County, Colorado. Colorado Division of Hazardous Materials and Waste Management; CDPHE. Water Quality Control Division. 1994. Exhibit 3, Upper Animas Water Quality Classifications and Standards Proposal. Colorado Department of Public Health and Environment. CHAPTER VI BIOLOGICAL & PHYSICAL ANALYSES INTRODUCTION .1 FISHERIES 2 Brief Summary of Findings ______2 Trout Species Life History Information 3 Cutthroat Trout______3 Brook Trout______3 Brown Trout „______3 Rainbow Trout ______3 Habitat______— ------4 MACROINVERTEBRATES ______6 Objectives Community Metrics______Sampling Methods and Apparatus Laboratory Procedures______Monitoring Stations Results ______—------**o Recommendations______—------Sampling Season______— ------— 8 Results ______—------———------Recommendations______------8 When and How Often to Sample ....------— 8 Results ______— ------—------8 Recommendations ______— ------— ------8 Benchmark Data Summary______—------9 Results______—------— ------— Metrics ______9 Physical Habitat______„ ______9 Recommendations______.—_ _ ------—------^ Comparison of Post Remediation Data to Benchmark Data------10 Recommendations ______^ Reference Sites Identified______—------jjj Indicator Species ------—------— Results______— ------__— Recommendations------^ Sampling Recommendations _------10 BIOTOXICITY STUDY (TROUT) 11 Purpose 11 Comparison of Biological Thresholds to Table Value Standards (TVS) Aluminum ...______— ^ Cadmium ------— ------y Copper______— 1 Iron ______14 M an g an ese______14 Z i n c ^ ______^ SUMMARY OF BIOTOXICITY REPORT (EXCEEDANCE ANALYSIS) 15 Segment 3a - Upper Animas______Segment 7 - Cement Creek ~ “ 16 Segment 9b - Mineral Creek below S Fork Confluence 17 Segment 3b Animas River between Cement and Mineral Creeks 18 Segment 4a - Animas from A-72 to Elk Park ______19 Segment 4b - Animas River from Elk Park to Junction Creek ______] 9 Summary of Toxic Exceedances for Each Metal at Seven Stations J20 Sum mary o f CD O W B iotoxicity E xperim ents______2 8 OTHER STUDIES AND FACTORS SIGNIFICANT TO AQUATIC BIOTA 29 Dissolved Metals versus Total Metals______29 Fish R ecruitm ent ______~ Precipitates and Colloids as Toxicants ~ ~3 0 Streambed Metal Sulfides______~ ~ 1 t Bioaccumulation______^ 1 Precipitates as Habitat Stressors (Smothering Stream Substrates)______32 Acidity and Alkalinity (as measured by pH units) 33 Anchor Ice 33 A nchor Ice Angler Pressure ______3 4 INCOMPLETE STUDIES______3 4 THREATENED AND ENDANGERED SPECIES CONSIDERATIONS______35 REFERENCES______36 APPENDIX 6A: FISHERIES REPORT APPENDIX 6B: MACROINVERTEBRATE REPORT APPENDIX 6C: BIOTOXICITY REPORT APPENDIX 6D: HYDROSPHERE REPORT (BIOASSESSMENT OF SEGMENT 4A) 41 LIST OF TABLES Table 6.1 Comparison of the protectiveness of Table Value Standards in Animas stream segments to Biological Thresholds (TVS) for 3 species of trout ______14 LIST OF FIGURES Figure 6.1 Animas River Fishery Community Distribution - Past and Present___5 Figure 6.2. Aluminum Toxicity Summary______22 Figure 6.3. Cadmium Toxicity Summary______23 Figure 6.4 Copper Toxicity Summary ______24 Figure 6.5. Iron Toxicity Summary______25 Figure 6 .6. Lead Toxicity Summary ______26 Figure 6.7. Manganese Toxicity Summary______27 Figure 6.8. Zinc Toxicity Summary ______28 CHAPTER VI BIOLOGICAL & PHYSICAL ANALYSES INTRODUCTION Like any ecosystem, aquatic ecosystems are restricted by natural limitations of conditions necessary to sustain life and reproduction. Temperature, flow regimes, food, habitat, oxygen, and metal concentrations are a just a few of the conditions. Limitations imposed as a result of human activities have resulted in increased sedimentation, removal of streamside cover, encroachment into wetlands and streams, and increased metal concentrations and reduced pH as a result of mining activities. To some extent, the trend of increasing limitations on aquatic biota can be reversed by natural processes such as flooding, dilution, or the ability of complex ecosytems to assimilate of certain amounts of contaminants. For example, before the closing of the Vanadium Corporation of America mill at Durango in 1963, the aquatic life of the river was adversely affected downstream to its confluence with the San Juan River (Tsivoglou, et al., 1958 and 1959). The population of bottom organisms in 1959 decreased from 360 organisms per square yard upstream from the mill to two organisms per square yard in the reach downstream from the mill. This decrease was attributed to toxic wastes discharged by the mill. By 1996, the population of benthic organisms had increased at the Florida and Animas Rivers’ confluence from 277 organisms per square yard in 1959 to 3,034 organisms per square yard. In 1961, prior to the closing of the mill, the Animas River between Durango and New Mexico did not support a trout fishery. Today the stream segment supports a thriving trout fishery including a Gold Medal fishery one mile downstream of the old mill. No human intervention to the aquatic system took place. By simply reducing the impacting sources, a relatively rapid recovery of this riverine system occurred naturally. Evidence suggests (the main improvement is the cessation of mining) remediation efforts have resulting in significant trout recoveries between Durango and Silverton. A group of ARSG participants, known as the Biology Work Group, set out in 1996 to collect information within the Animas watershed to meet three primary objectives; 1) provide benchmark biological and physical conditions to which future remediation effectiveness can be compared, 2) provide information on historic and recent trends, and 3) provide insight into factors currently responsible for limiting aquatic life. Many chemical, physical, and biological parameters were investigated. The results of those efforts are listed in three major reports. Most of this chapter is devoted to summarizing those reports. Other information is provided following the summaries. FISHERIES Fish are at the top of the food chain in the Animas River watershed and as such can be used as valuable indicator species for determining general health and function of the aquatic environment. A Fisheries Report: Current and Historical Review of Animas W atershed Fisheries is provided as Appendix 6 A. A collaborative effort of members of the Biology Work Group and EMI, an ecology contractor, created this document for the following purposes: 1) to compile and summarize all available fishery information, past and present on the Animas riverine system, 2) To compile and summarize available information on the historical and current fish habitat condition, 3) To provide information (present condition and trends) for use in the Limiting Factors Analysis and, 4) To make recommendations for future fish monitoring to enable quantification of changes in fisheries as a result of remediation of mine sites. The report is limited by both the quantity and quality of available data. The Animas canyon area is particularly difficult to assess due to its remoteness, difficult access, and dangers associated with a high gradient, confined channel. Attempts were made each year for four years to collect data in the canyon and above Silverton before conditions were safe enough to succeed. Evaluation of habitats has been difficult as well. Fish population data is mostly available from below Durango where access is easy and the fishery is very good (including a short section of Gold Metal designation). Minimal available data is compounded by the fact that much of the sampling done over 2 0 years ago used less rigorous methods and protocols than today. Nevertheless the Fisheries Report is still very informative as a compilation of all data available. It is an unbiased attempt to summarize the existing conditions and present possible trends. Brief Summary of Findings Many native species of fish were present in the Animas below Baker's bridge before the first Euro-American settlers arrived. It is unknown if or how far they had colonized above this point. Settlers introduced non-native trout species throughout much of the watershed by the 1880's, including within the Silverton caldera. Fish populations have been impacted by mining activities since at least the turn of the century. Today's populations vary widely in size, composition, and health but there are indications that there has been an improving trend, in both the lower and upper basins. With the exception of a sculpin collected in South Mineral Creek, trout are the only fish species recorded above Baker's Bridge. It is likely that sculpin are in the canyon area and the one capture recorded in South Mineral Creek hints that they may have been in the Upper Basin as well. Being a native fish, they hold promise for use as an indicator fish. They have not been specifically sampled for and are easily overlooked. Cutthroat trout is the other fish native to the Upper Basin. It is highly sensitive to metals toxicity and only exists in relatively clean tributaries. Other trout, brook, brown, and rainbow are not native to Colorado. Brook trout are able to reproduce in Segment 3a. Recruitment of young trout appears to be occurring throughout most of the Animas canyon; juveniles are probably arriving from tributaries (stocking was suspended from 1996-1999). Recently, trout have been recorded as reproducing in the lower Animas around Durango for the first time. Trout Species Life History Information Cutthroat Trout, Oncorhynchus clarki sp. Colorado cutthroat trout are native to the Upper Colorado River basin above the Grand Canyon. This species evolved in isolation from rainbow and other trout and is highly susceptible to hybridization with rainbow trout. In the 1880's and 1890's rainbow trout fry were introduced to many of the major tributaries of the Upper Colorado River Basin. Cutthroat are spring spawners. Small isolated populations of native trout exist in some headwater streams although their numbers are extremely limited due to the need for high water and habitat quality. These trout do not compete well with other trout for habitat or food. They are usually the most sensitive to elevated metals. Brook Trout, Salvelimsfontinalis. The brook trout is a North American endemic species that has been introduced into the Animas River. Brook trout are typically fall spawners utilizing gravel shallows in creeks and lakes. Preferred foods include aquatic insect larvae and terrestrial insects. The brook trout are able to withstand higher acidity, elevated metals and colder waters (except cutthroat) than other trout species although their growth rates may be considerably reduced in water quality impaired habitats. They are found at equal or just below in elevation from cutthroat. Brown Trout, Salmo trutta. The brown trout is native to Europe and western Asia and was first introduced in the United States in 1883. The brown trout is a fall spawner that typically utilizes warmer waters than the rainbow, brook or native cutthroat trout. Optimum temperatures range from 18.3 to 23.9 degrees C. Therefore they typically are located in lower reaches of rivers utilizing shallow gravel areas for spawning. Brown trout typically utilize a wide variety of food organisms, particularly aquatic and terrestrial insects and their larvae, crustaceans, and a wide variety of fish. These species are the best competitors for habitat and food. They eat their own and other species young. They begin to prosper below 9000 feet in elevation. Except for copper, brown are more susceptible than brook to elevated metals but not as sensitive as cutthroat or rainbow. Rainbow Trout, Oncorhynchus mykiss. The native range of the rainbow trout was the eastern Pacific Ocean and the freshwater areas west of the Rocky Mountains. Rainbow trout are spring spawners and prefer spawning in smaller streams in fine gravel in a riffle usually above a pool. Preferred spawning temperatures vary between 10.0 and 15.5 degrees C. Eggs usually hatch in 4 to 7 weeks, varying with region, habitat and substrate quality. Rainbow trout depend on invertebrates including plankton, larger crustaceans, insects, snails and leeches. These species are the least habitat specific. They can compete with other species and can co-exist without dominating. Their natural distribution is more a function of stocking and conditions that sustain their populations once stocked. They could occur in the Animas headwaters down to below Durango. H abitat By all accounts fish habitat is at least minimally adequate throughout the Animas below Elk Park. Segment 3a and South Mineral Creek have adequate habitat although limitations do exist such as adult and rearing cover, stream bank cover, deep holding pools, and minimal spawning habitat. None of these factors would exclude fish survival by themselves but together they put stress on individuals and populations. Segments 2,7, and 8 have no fish, and habitats were not closely analyzed. Metal concentrations in the water are too toxic for fish survival, however, if remediation were to reduce metals to the point where toxic conditions were not a factor, habitat from historic armoring of substrates would be a limiting factor unless improvements, either by manipulation or nature, occurred. The report provides farther information on habitat conditions within each stream segment examined. The following schematic, taken from the text of the Trout Report, provides a summary of historic and current fishery populations within the Animas Watershed. Figure 6.1 Animas River Fishery Community Distribution - Past and Present I R ! Fry B KEY 1 Cement C=Cutthroat B=Brook Minnie G L=Brown R=Rainbow II=Hybrid Fry=Fry *=few ???=not sure History suggests cutthroat were dominant and later brook took over segment boundary Fry a \ ft V B =\vas present □ \ 's. ? it one rim« *Note: most tributaries to CC, MC, and Upper Animashaveno fish. Exceptions: S. Mineral (B,R), Cunningham (B,C), Minnie (C), and Maggio / (B,C), Nearly all tributaries below Silverton Mineral contain trout. \ / \ i k 3b B* 9a S Mineral , ____- — ì r\ 9b R* y a S r n ln in Bandora Mine 4a ?? Deer Cr Molas Cr I“" Elk Cr !,_1 B C* R* 4b B increase in downstream direction to Cascade Creek, probably decrease to Baker's bridge (lower range) have been collected further upstream B R Cascade Cr B, R, L, C, II —not significant change ‘92-98, solid fishery Brown begin to out # other, rainbow next highest Baker’s Br B, R, L-L reproducing, R just last few years B drifters from upstream Junction Cr Sculpin, some o f species listed below in Segment 5 KEY 2 Fishery L.R dominate upper most Seg 5 Recovering/Marginal Few C, mostly stocked by SUT and swim up to cold II2o Fishery SU Tribe All «her species listed increase downstream: Sculpin,fathead minnow, carp, Johnny Darter, fannelmouth S, speckled dace, bluehead S**, white S, channel catfish, round tail chub, red shiner, bullhead S** MACROINVERTEBRATES Macroinvertebrates are one of the oldest living group of organisms on the planet. In aquatic environments they feed upon primary producers (algae), fungi, and other invertebrates. In turn, they become important food sources for water birds and fish. The following discussion refers to species that prefer running water environments such as rivers and creeks. Three primary cold, clean water indicator species in the Rocky Mountain Region include, stonefly (Plecoptera), mayfly (Ephemeroptera) and caddisfly (Tricoptera). In rivers, they are found in more diverse numbers and densities in erosional zones such as a riffle. Riffles are typically a substrate composition of rubble, cobble and loose gravel with some boulders. These areas are usually devoid of silt. Depositional areas, such as pools, which have slower deeper water have fewer bottom dwelling macroinvertebrates, perhaps a large number of a few dominant species. Aquatic macroinvertebrates have adapted to both the aquatic and terrestrial environments to complete their life cycle. When an insect transforms from an aquatic stage to a terrestrial stage, it is referred to as a hatch. The beginning of most aquatic insects life cycles starts by the adult female ovipositing (the act of laying or depositing eggs) in the water by dropping eggs on or into the water while in flight or while resting on the water’s surface. A few dive into the water and deposit on the substrate or vegetation. Each organism will go through a series of form changes in the water before they hatch, which are called life stages. There is the egg stage of embryonic development, postembryonic (everything between egg and reproducing adult) and adult sometimes called an imago. Some species growth occurs as an increase in size, and morphology remains basically the same. As with a snake each growth spurt requires the molting of the exoskeleton. In between each molt the individual is an instaar stage, and species’ instaars can range from 4-40 in frequency. The first postembryonic life stage is called the larval stage which can be followed by adult or more postembryonic stages and usually involving three instaars. The next stage is subimago, which is only found in mayflies, is a fully winged form and includes only one instaar. The next stage is the pupal stage which is primarily a maturation stage (like puberty). It may involve a case or be free living. Insects that do not have a pupal stage have incomplete metamorphosis (transition to adult). Each larval stage includes growth and maturation (moving toward puberty) versus just growth. Morphologically there is little difference, other than size, in each instaar. These stages are often called nymphs and used by dry fly anglers. A damselfly is an example. Insects that do have pupal stage have complete metamorphosis, more advanced or evolved. Growth takes place primarily in the larval stage and maturation in the pupal stage. Each larval stage typically looks very different that the past stage. A midge is a classic example. Diversity and density of a typical Rocky Mountain stream is relatively very rich compared to the same unit of “ground” on land. This is because of the incredible number of niches aquatic organisms fill in their life cycle. For example, some organisms have one generation per year, some two, some none. They may reside in vegetation, on top of substrate, in between, in the sediment, in riffles, or in the littoral zone. Macroinvertebrate populations of streams impacted by mineral loading differ significantly from those found in watersheds with little mineralization. The complexities involved are just now beginning to be understood. It has been thought that if populations could be sampled, evaluated, and statistically described, it might be possible to establish benchmark conditions (existing conditions from a series of synoptic samples) with which to compare and determine changing conditions, particularly changes brought about through remediation efforts. Macroinvertebrates Report The purpose of the Macroinvertehrcttes Report, Appendix 6B, is to 1) describe the condition of the existing macroinvertebrate communities (benchmark condition) and 2) to establish a protocol to use for comparing post-remediation data to this benchmark data for assessing the effect of mine site remediation on the macroinvertebrate community in the Animas River watershed. A summary of the report follows. Objectives The primary objectives were to establish protocols and methods, identify sampling stations and sampling frequency, and establish benchmark community structure and function to gage the effect mine site remediation has on the diversity of the macroinvertebrate community and the physical habitat. Community Metrics This section identified community metrics with which to define the benchmark data and with which to compare the post-remediation data to the benchmark data. Results: Taxa richness and evenness are used to define the benchmark data. It was determined that taxa richness will reflect expected changes in macroinvertebrate communities in the Animas River. Recommendations: If it is deemed necessary to more accurately define the benchmark data and to better ascertain the effectiveness of mine site remediation, metrics that do not highly correlate with taxa richness may be calculated from the biomonitoring data. It may also be necessary to test the effectiveness of different community metrics at measuring the impacts of acid mine drainage using protocols outlined by Resh and Jackson (1993). Sampling Methods and Apparatus Methods and apparatus used in establishing the benchmark data are presented and recommendations for post-remediation sampling are provided. VI-7 Results: Several sampling appartii were considered and four differ appartii were used in fall 1996 samplings. It was determined through comparisons that a modified Rectangular Dip Net would give the most reliable and consistent results throughout the Animas watershed. Sampling was modeled after EPA's Rapid Bioassessment Protocol. Sampling occurred during the fall of 1996, and the spring and fall of 1997. Multiple samples were obtained and individually analyzed for each station rather than composited. Recommendations: Future sampling should follow the same sampling protocol used in 1997 and use the same type of modified Rectangular Dip Net. Laboratory Procedures The objectives of this section were to review and identify laboratory procedures that were used to establish the benchmark data and to recommend procedures for post-remediation sampling. Results: Laboratory procedures are described. Recommendations: Recommendations are provided for future laboratory procedures that will give cost efficient and comparable results to baseline data. Monitoring Stations Many sampling stations used in establishing the benchmark data are stations identified for use in post-remediation evaluations. Results: ^ Baseline data was gathered from 65 stations located throughout the Animas. Stations included within the Animas, above and below major tributaries, and the mouths of major and reference tributaries. Water chemistry samples, physical habitat characterization, and macroinvertebrates samples were taken at each station. Sites upstream of tributaries were chosen for establishing baseline conditions on the Animas. Reference stations and control stations were chosen within tributaries. Trends in macroinvertebrate, water chemistry, and physical habitat indicate that significant impacts to the Ammas River are coming from four stream segments: the Animas above South Fork, South Fork of Animas, Cement Creek, and Mineral Creeks. Recommendations: Recommendations for sampling locations and techniques to assess the results of remediation within sub-basins as well as for the Upper Animas as a whole are suggested. Statistical tests to determine trend changes while accounting for year to year variation are also recommended Sampling Season An evaluation was made as to whether assessing the effects of mine site remediation is more or less representative when conducted in either spring or in fall. Results: Sampling was conducted twice during the fall and once during the spring. There was no statistical difference between fall 1996 and spring 1997 results. Overall taxa richness in fall 1997 was significantly different than fall 1996 and spring and fall 1997. This indicates year to year variation can be significant. Advantages and disadvantages to fall and spring sampling are provided. Recommendations: It is concluded that fall sampling, done as close as possible to the time of the sampling event for the fall baseline condition, would be preferable and more practical than spring sampling. When and How Often to Sample When and how often sampling should occur is important given economic constraints of any program. These considerations are provided for monitor planning purposes, Results: Factors influencing the rate of recovery of benthos after remediation are discussed. ^ Due to existing sediment, metal loads and other factors, several years of recovery might be necessary before statistically significant trends for macroinvertebrate improvement can be identified. Recommendations: Ideally, sampling should be accomplished yearly at selected reference sites to provide information on yearly variation of macroinvertebrate populations so that statistical trend analyses will be able to account for this variable However, monitoring the results of remediation on benthos need only be done following appreciable remediation efforts, whether the monitoring be done on a local or more basin- wide basis. To be cost effective, biomonitoring should follow a discernable improvement to water quality by at least two years. Benchmark Data Summary Benchmark data for both the macroinvertebrate community and the physical habitat are presented for the locations sampled. Results Metrics: The existing baseline conditions of macroinvertebrates throughout the watershed are presented in the report itself. Also taxa richness and evenness are provided for sampled areas. The degree that the macroinvertebrate community is impacted by acid mine drainage varies from site to site. Only a few species of macroinvertebrates live in the Animas River near Eureka Gulch as well as in the Animas between Boulder and Kendall Creeks. There is a peak in the number of species in the Animas between Cunningham and Boulder Creeks and a recovery in the number of species from Mineral Creek to Baker’s Bridge. Few species exist in South Fork of the Animas (often called Eureka Creek) and in the Cement and Mineral Creek drainages. Cunningham, Boulder, and South Mineral Creek as well as tributaries below Silverton have a large number of taxa. Trends in macroinvertebrate densities are similar to trends in the number of species, although the rate of recovery of macroinvertebrate densities from Mineral Creek to Baker’s Bridge is not as rapid as is the rate of increase in the number of species. Below Baker’s bridge, taxa richness levels off but densities continue to increase to stations below Durango. Tributary benthos conditions are also provided in the report. Physical Habitat. Quantification of habitat conditions is most difficult. Photographs of physical conditions were taken at each sample station. Interstial space (space between substrate particles), cementedness, and precipitate impacts are evaluated for each station. Adequate interstial spaces for benthos were available throughout most of the basin but were minimal in the Animas just above Boulder and Elk Creeks. Cementing of substrates occurs above and below Elk Creek. It appears that cementing does not limit the diversity of macroinvertebrates at either of these stations, Precipitates are the only physical habitat feature with a measurable relationship to macroinvertebrate taxa richness. Accumulation of orange precipitates on substrates is greatest in Cement Creek and Mineral Creeks and gradually decreases downstream. (Substrates in the upper parts of Mineral and Segment 2 of the Animas were not evaluated but are known to have accumulations of precipitates). Precipitate accumulation has an inverse relationship to taxa richness Exceptions to this generalization include the South Fork Animas and Cement Creek below North Fork where the quantity of precipitates was low but there were few macroinvertebrates (this may be due to toxically low pH and metals are all dissolved). The other exceptions are on South Fork of Mineral before the confluence with Mineral mainstem and on the Animas above Cunningham and Boulder Creeks. These areas had observable precipitates on substrates with relatively high numbers of taxa and densities of macroinvertebrates. Recommendations: Future samplers should have copies of the baseline photographs for each station with them when sampling in order to make visual habitat comparisons. Since precipitates on substrates appear to be the only physical habitat-limiting factor at this time, future sampling should concentrate on this feature. Comparison of Post-Remediation Data to Benchmark Data The report outlines statistical and qualitative methods for comparing post-remediation data to the benchmark data. Recommendations: Year to year and sampling accuracy variations must be accounted for in future sampling schemes. T-tests and ANCOVA are recommended as basic statistical methods for post-remediation data to the benchmark data. Methods are described, and hypothetical examples presented. Reference Sites Identified Reference stream sections were identified as reference sites that can be used as indicators of the conditions of streams that originate in highly mineralized basins that have no mining related impacts. Results: Stream stations are identified that can serve as reference sites for both solfatarically altered and propylitically altered, vein type geology. Indicator Species An attempt was made to identify macroinvertebrate species that may be expected to colonize impacted segments as they recover from acid mine drainage. Results: Until necessary environmental conditions are known for specific taxa of macroinvertebrates and a limited factors analysis is completed for the potential candidates, indicator species are difficult to predict. However, taxa that begin to appear in a downstream gradient fashion, as water quality improves, can be useful in determining what to expect as conditions improve upstream. Various taxa are described that might be used in this regard. Recommendations: Completion of a limiting factors analysis for taxa considered for use as indicator species. Unfortunately only minimal biotoxilogical studies have been completed on macroinvertebrate species common to the Animas watershed. Taxa suggested as possible indicator species need to be further considered. Sampling Recommendations Many recommendations are presented in the report for future sampling of changes in macroinvertebrate conditions. Sampling and analysis is a costly and time consuming process that may or may not provide reliable information. Previous macroinvertebrate sampling programs lacked the consistency and scientific rigor necessary to draw statistically significant conclusions. Using macroinvertebrates to assess the riverine ecosystem and measure impacts of remediation is in its infancy. Reliable data must be attained and then analyzed using sophisticated multivariate statistical analysis methods. If a program is not developed with forethought of purpose, strict sampling protocols, rigorous scientific methodology, and an extensive commitment of time and funds one has to question its potential usefulness. BIOTOXICITY STUDY (TROUT) A thorough analysis of actual biological threshold (BT) exceedances for three species of trout was compared to water quality data collected by ARSG participants over the past ten years and is presented in Appendix 6C. Biological thresholds are species specific acute or chronic toxicity concentrations for particular metals. The biological threshold exceedances were also compared to hardness adjusted Table Value Standards (TVS) exceedances. TVS are design to protect 95% of the aquatic organisms operating on the principle that if the most sensitive species is protected so are all others. This study is specific to Segments 3a, 9b, and 4a, for which a UAA is required. Trout were chosen for this purpose because toxic thresholds have been determined, reviewed, and generally accepted whereas less is known about the thresholds of other high elevations aquatic organisms. In addition, trout are the most likely species to occur in the basin, and being at the top of the food chain, reflect the general health and vitality of the aquatic ecosystem. The report also includes a detailed section summarizing all bioassay studies and on-site biotoxicity results for three species of trout, for copper and zinc, over three seasons, using Animas river water from Segment 4a. Laboratory toxicity results were run at the same time and compared to the on site studies. This extensive investigation was accomplished by CDOW (Pat Davies, Steve Brinkman, and Barb Horn) for ARSG to ensure the accuracy of the biological thresholds used in the analysis of the biotoxicity report. Barb Horn is also the lead author of the biotoxicity report. Purpose The design and purpose of the Biotoxicity Report is to: a) determine the adequacy of TVS for protecting species reflective of conditions necessary for attainment of the Cold Water Aquatic Use Classification by comparing TVS exceedances to biological threshold exceedances of rainbow, brown and brook trout, b) use actual data collected over a ten year period to enumerate species specific biological threshold exceedances of metals, and the frequency, duration, seasonality and magnitude of those exceedances (potential toxicity), c) provide an analysis that can be used in the future to determine emerging limiting factors as initial limiting factors are remediated, d) provide a comparison of exceedance occurrence, frequency, duration, seasonality and magnitude (potential toxicity) to those of the regression model presented in Chapter VIII. Comparison of Biological Thresholds to Table Value Standards (TVS) To fully understand the value of this comparison a brief description of where Biological Thresholds and TVS’s are derived is included. Biological thresholds are derived from bioassay or toxicity studies. Bioassays focus on a specific metal and species. In a series of tanks, either in a laboratory or in the field, a bioassay will expose test organisms to increasing doses of a specific metal for 96 hours. Each tank has a specific metal concentration and all other constituents are held constant. A metal specific acute 24-hour and chronic 96-hour LC 50 can be calculated. An LC50 is the least concentration (LC) that killed 50% of the test organisms. In comparison, a toxicity study will take in-situ stream water and expose a species and see how long it takes for 50% of the organisms to die. The water is then analyzed to hypothesize the culprit metals. It is unknown in a toxicity study which metal caused the toxic response if more than one metal was elevated. In the Biotoxicity Report and in the UAA a biological threshold (BT) refers to criteria from bioassays in recent literature for brook, brown and rainbow trout. Table Value Standards (TVS) are design to protect 95% of the taxa present (i.e. does not protect all taxa and individuals present). Colorado's TVS’s were updated mid-year in 2000. Those updates are reflected in the UAA, Chapter VIH and elsewhere, but not in the Biotoxicity Report since the analysis was completed before this update. Most of TVS for metals are equations that include inserting a hardness value, TVS are developed and updated by the following general process. All the toxic thresholds (acute or chronic) are compiled for each species that data exists, warm and cold water, game and non-game species. Thresholds that don’t meet a conservative list of criteria are removed from the database. All values are then normalized to one hardness, usually 50 mg/1 CaCC>3, because the individual tests are all completed with different hardness values. Then a mean acute threshold for a constituent (e.g. zinc) is determined for each species. These species’ mean acute values are all combined and a regression line dictates the continuum of most to least sensitive. The point on the regression line that “represents” 95% of the species becomes the TVS. The combination of the four most sensitive species mean acute values usually comprise the final acute TVS equation. For zinc, those species are two daphnia species, stripped bass and long fin dace. (Rainbow trout are sixth and brook trout are 14th in the continuum.) Because the TVS equation may or may not include actual biological thresholds for the species of concern, it is a valuable exercise to compare species specific BT’s with TVS’s. In addition, sometimes the most common occurring (present or historically) and or attainable species is not the most sensitive. Since TVS is designed to be an “umbrella” to protect 95% of the taxa or community, if TVS is exceeded one does not necessarily know if the species that is attainable or present in the segment is really protected unless one looks at that species’ specific thresholds for the limiting factor. Thus, a comparison of Biological Thresholds to TVS can provide: 1) a more specific insight to community potential and/or why the community structure is not what it appears it should be, because BT provide a review of individual species, criteria versus the umbrella protection TVS supplies, 2) more diverse scenarios for potential remediation than just using TVS criteria, because the species specific information is present, 3) a degree of confidence surrounding potential toxicity (what the numbers say) versus actual toxicity (what is actually occurring), and 4) a degree of confidence that TVS are actually protective to individual species. BT (TVS protect) doesn't TVS=BT TVS over TVS = BT =TVS protectsallsp. No Exceedances No B criteriaNo RforTVS hileover w (useBT) protects Lprotects 9b Chronic Acute TVS* TVS over- TVSover- protcctsB; under protects L,R. TVSBT for = =TVSBT forR, (except R thenBT) No Exceedances TVS over- B; protects TVS=BTL for BT) (use BTRfor slightly over- slightly TVS=BT TVS (probably TVS (probably sp. TVS BTB,L for Protectrve all all Protectrve =BTTVS No Exceedances NoB criteria BT=TVSfor L,R BT) (use 4b Chronic Acute TVS* TVS (probably TVS (probably over-protective all sp.) TVS =BT TVS TVS (except for (exceptR, thenBT) No Exceedances over-TVS BT) (use protectsB,L; forBT R Most Protective Criteria TVS=BT Acute doesn’t protect) doesn’t BT (TVS TVS TVS = BT TVS = No B criteria No BT) (use BT over-TVS protectsL,R 4a ______Chronic TVS* TVS=BT TVS = BT = TVS for R, (except TVS=BT thenBT) BT TVS over- L, Rfor under BT) (use protects B, B, protects Acute TVS=BT protect) doesn't BT (TVS TVS TVS =BT BT B No criteria TVS approx.= BT 3a Chronic TVS* over TVS protects B; B; protects TVS BT=TVS for BT=TVS L, R TVS = BT TVS R, for(except thenBT) BT TVS over B, protects under-protects L,R. (use BT) (useL,R. Table 6.1 Comparisonthe of protectiveness (TVS) for of3 trout. species of TableValue Standards inAnimas streamsegments toBiological Thresholds (For metals that have high potential as Limiting Factors) Limitingashigh potential thathave (Formetals METAL Cd A1 Cu Fe Mn Zn ♦TVS ♦TVS rainbow forbutbrownbrooktrout andfor pHranges allfor ug/1 setat 87 is forTVS andBT criteria does. pHwhileforBT Chronic variable no has TVS trout BT is 750 ug/1 when pH >7.0. >7.0. pH when ispH7.0 Below 87ug/I. the criteria ug/1 is BT 750 trout VI-14 • Aluminum Currently accepted criteria are based upon dissolved values. Acute toxicity criteria for BT and TVS are identical. Chronic criteria for BT and TVS is set at 87 ug/1 for all pH ranges for brown and brook trout but for rainbow trout BT is 750 ug/1 when pH >7.0. Below pH 7.0 the criteria is 87ug/l. • Cadmium Biological Thresholds and Table Value Standards are nearly equal in protection of aquatic life at Segments 4a and 4b. TVS over-protects brook trout at 3a and 9b, while under-protecting brown and rainbow at the same locations. Since brown trout might be expected to inhabit Segment 3a, and since little protective difference exists between TVS and BT for Cadmium at other stations it is suggested one TVS be used for setting chronic standards for all segments. The more stringent Biological Threshold criteria should be considered when setting acute standards however. • Copper TVS provides adequate protection for all species of trout for all stream segments, however they tend to be more protective than necessary for the 3 trout species considered. • Iron Use TVS as basis for setting stream standards for all locations, BT is lower (500 ug/1 Vs 1000 ug/1) for rainbow trout so that could be considered as a standard to protect that species. However, given the overwhelming Fe loads from natural sources that are primary limiting factors in all segments other than 3a (see Chapter VIII), one might only consider this more stringent alternative for that segment. Also, reducing iron, which has been shown to be beneficial in sorbing Cu and Zn to its colloidal surfaces, may be more detrimental than desirable, particularly in Segments 3a and 2 where Zn and Cu concentrations are limiting factors, and iron is not. • Manganese Biological Threshold criteria are more stringent for all species of trout than are TVS. However, only minimal reductions in Mn can be expected as passive treatment is unsuccessful for this element and active treatment is excessively expensive. Surface waste and adit infiltration prevention are the only practical solutions for reduction at this time. Using TVS as the basis for establishing standards may be a more practical approach at this time. • Zinc Biological Threshold criteria should be considered for setting stream standards in all stream segments. The presence of three species of fish in Segment 4b, and brook trout in both lower 4a and all of 3a indicates these fish have adapted or are in some way able to be sustained in these waters in spite of numerous chronic and acute exceedances of TVS. Summary of Biotoxicity Report (Exceedance Analysis) The following paragraphs and schematics summarize toxicity exceedances determined in Appendix 6C. See Appendix 6C for more details, Segment 3a - Animas from Minnie Gulch to above Cement Creek (Characterized by A-68) * This evaluation uses data from A-68, which is at the extreme low end of segment 3a. The limiting metals at this location include: • Aluminum, in mostly total fraction, is moderately limiting using TVS criteria and not limiting using biological threshold criteria for values over 87 ug/1. This holds for all trout species. The magnitude of exceedances is not large, spring and fall seem to be more critical seasons. • Cadmium for brook is medium to low limiting with a lower frequency and duration of exceedances than for other trout but there is a four month duration when exceeded. April is the month for maximum and minimum extremes (what are max and min extremes???) for brook, corresponding to the time of a sensitive life stage. Cadmium for brown is highly limiting, mostly chronic exceedances, high frequency, four-month duration, every year, April produced maximum exceedances, and November the lowest exceedance value for brown and rainbow. Cadmium for rainbow was even more limiting than for brown with twice as many acute exceedances and equal chronic exceedances. Majority of exceedances were not of large magnitude, thus small decreases might result in large improvements. TVS for chronic criteria match biological criteria exactly. This was not so regarding acute criteria where TVS are not protective of any species' biological thresholds. • Copper is low to medium limiting for most species. Copper does not have a discemable pattern of being in the dissolved or total fraction. If any pattern exists copper is only dissolved about 30% of the time, reducing potential toxicity. Brook trout are more sensitive to copper than other species. TVS had twice as many chronic exceedances as chronic BT criteria but 13 acute exceedances whereas BT recorded no acute exceedances. Brook trout are the most limited species regarding copper levels. Toxicity is probably at chronic level and magnitude is not large, about 5 ug/i over criteria. May and June seem to provide dilution for elevated copper whereas the most occurrences were in the spring and summer months. • The number of iron exceedances is among the top of all metals. Iron is primarily in the total fraction. Iron is low limiting for brook and brown and medium to low for rainbow. The lowest exceedance occurred in May and highest in April. Most exceedances were less than 1000 ug/1 over criteria, however events were measured with iron values of 5000 and 6000 ug/1. • Lead is not limiting or very low limiting for all trout species. TVS and BT criteria correspond with each other regarding lead exceedances. Lead is not detected frequently relative to other metals and when it is, it is primarily in the total fraction. Spring and summer are the likely times for detection and few exceedances. • Manganese was detected in every sample at this location and is primarily in the dissolved fraction. The BT criteria would suggest Mn is low to medium limiting for VI-16 brook and brown and less for rainbow, mostly chronic. TVS criteria would suggest Mn is low to not limiting. The extreme low exceedances for BT occurred in September and January and the high in May. The extreme low exceedances for TVS occurred in January and August and high in March. Spring and winter had the most exceedances for both criteria. Exceedances occurred every year for about 1-5 months in duration. • Zinc, like manganese was detected in every sample and was almost always in the dissolved fraction. Zinc is medium limiting for brook trout at a chronic level with not extreme elevated levels but long duration and high frequencies. Browns are highly limited using chronic criteria but medium limited using acute criteria. Almost every value measured exceeded the chronic brown criteria. The magnitude of exceedances is very high, along with frequency and long duration. Rainbow are highly limited using both chronic and acute criteria. More than of the values exceed acute rainbow criteria. Chronic TVS protects brook trout but not brown and rainbow. Acute TVS represented about an average of the individual BT protection for brown and brook. Segment 7 - Cement Creek (characterized by CC-48) This station is above the confluence with the Animas River thus represents Cement Creek’s contribution to the Animas. There are no aquatic life classifications for Cement Creek thus no stream standards for BT comparisons. • Aluminum is highly limiting to all species. It was detected in almost all samples and dissolved 2/3 of those samples. All but 6 samples exceeded 87 and 750 ug/1 (acute and chronic respectively), thus exceedances occurred every year, all the time, fairly evenly distributed over each season. Magnitude of exceedances is large both chronic and acute. • Cadmium is medium to highly limiting for brook and highly limiting for brown and rainbow. Limitation is chronic for brown and acute for rainbow. Magnitude is not large, only 1-2 ug/1 over criteria. Most exceedances occurred in spring, summer, fall then winter. The highest exceedance values occurred in November. • Copper is medium to highly limiting for brook and highly limiting for brown and rainbow. Brook limitation is chronic and other species is acute. Copper was primarily in the dissolved fraction. Exceedances occur every year evenly distributed across all seasons. Spring is the season for high chronic exceedances and fall for acute. • Iron was detected in all samples, primarily in the total fraction. All values exceeded rainbow chronic criteria and most exceeded 1000 ug/1, other species acute and chronic criteria. The low exceedance occurred in June and the high in April. Spring season had the most exceedances followed by fall. Most of the exceedances are 1000-5000 ug/1 over criteria, 20% were less than 1000 ug/1 over. Iron is limiting to all species. • Lead is Va dissolved and V2 in total fraction. No acute criteria were exceeded. Lead is low limiting for brook and brown and highly limiting for rainbow. A rainbow chronic criterion was exceeded every year, primarily in the fall, duration of 1 month about 5-15 ug/1 over criteria. • Manganese was primarily dissolved and chronically limiting to all species. For brook and brown exceedances were distributed throughout the seasons with the highs in March. Rainbow exceedances occurred the most in spring, summer, then fail for 2-3 month duration • Zinc was detected in all samples primarily in the dissolved fraction. Brooks are medium limited, mostly by chronic exceedances. Browns are highly limited with a combination of acute and chronic exceedances. Rainbows are highly limited mostly due to acute exceedances. Low and high exceedances occurred in November or June. Summer was the most exceeded season followed equally by spring and fall, then winter. Duration is greatest in the spring but generally lasts 6 months or so. Most of the exceedances were 350-600 ug/1 over for brown and 450-850 over for rainbow. Segment 9b - Mineral Creek below S Fork Confluence (characterized by MC-34) • Aluminum appears to be primarily in the total fraction much of the year but in the dissolved fraction during the winter. Aluminum is highly limiting for all species. Highest exceedance occurred in November, winter is the most frequently exceeded season. The magnitude of exceedances is high for both acute and chronic. Duration of exceedance is about 6-7 months. TVS correlates with BT criteria suggesting pH does not make that much difference with this data set. • Cadmium is less limiting here than at CC-48, A-68 or A-72. Brook are low to medium, brown and rainbow medium to highly limited. A BT acute criterion was exceeded for brook and rainbow, and TVS was not. Spring is the most exceeded by a small magnitude but for 2-3 months. Chronic TVS are not as protective as BT for brown and rainbow, Acute TVS are not as protective as BT for any species. • Copper is present as dissolved in of all values. Brook are highly limited, brown low to medium and rainbow medium to highly limited. Most exceedances occurred in spring, summer, fall then winter for duration of 9-10 months and mostly 5-15 ug/1 over criteria. TVS protect brown but brook are more sensitive and more likely to be present. • Iron remains highly detected in the total fraction. Two thirds of the values exceeded 1000 ug/1 and almost all values exceeded 500 ug/1. Spring and summer are most exceeded seasons with magnitudes 1000-3500 ug/1 over criteria for l/2 of the values. About 20% of values were 4000-7000 ug/1 over criteria. Iron remains limiting for all species. • Lead was detected in some samples but not limiting. A few BT and TVS chronic criteria were exceeded but do not appear to be limiting. • Manganese is in the system but not limiting. No BT or TVS criterion was exceeded. • Zinc was detected in all samples and in the dissolved fraction. Brooks are not limited. Browns are highly limited with a combination of acute and chronic exceedances. Rainbows are highly limited mostly due to acute exceedances. Chronic TVS correspond with brown chronic BT exceedances but do not protect rainbow. Acute TVS protect both brown and rainbow more than acute BT criteria. There were values in the data set that exceeded criteria but a corresponding hardness value was not available to compare with a stream standard. For chronic exceedances summer was the highest exceeded season, then spring, fall and winter. For acute exceedances there were no difference between summer and spring, followed by winter then fall. Duration of chronic exceedances was 9-10 months and for acute was 1 week to 1 month. Magnitude varied. Segment 3b Animas River between Cement and Mineral Creeks (Characterized by A-72) This segment of the Animas River is a mixing area from the upper Animas River and Cement Creek. The river is not frilly mixed as Mineral Creek enters the Animas and continues to mix in Segment 4a. • Aluminum is primarily in the total fraction and remains limiting to all species but not to the degree as in Mineral and Cement Creeks. TVS and BT corresponded with each other unlike at A-68. Acute criteria was minimally exceeded but the aluminum toxicity was chronic in about H of the samples evaluated. Extreme high values that exceeded criteria occurred in March. However exceedances occurred in all seasons, more in winter then spring. The magnitude of exceedances were all less than 1000 ug/1 over criteria for chronic and acute. Aluminum might be limiting but probably does not preclude all aquatic life. • Detected cadmium levels decrease from 80% of the samples to 36% of the samples compared to A-68. BT and TVS chronic and acute exceedances decrease for all species, decreasing the limitation of cadmium. Brown continues to be chronically limited and rainbow both chronically and acutely limited. Spring continues to be the chronic season of concern and winter the acute season. Chronic TVS correlates with chronic BT criteria, but acute TVS are not as protective as acute BT criteria. • Detected copper decreases as cadmium did but to a lesser degree. Copper is not consistently dissolved or in the total fraction, Brook and rainbow remain low to medium limited and brown are not limited by copper levels. Duration is for 1-2 months with 5-15 ug/1 over criteria for magnitude. Winter had the most exceedances whereas at A-68 spring and summer had the most exceedances. Chronic TVS correlated with BT criteria, however acute TVS were more conservative than acute BT criteria. • Iron remained highly detected and in the total fraction. Iron remained above criteria most of the year, every year for all criteria. Magnitude of exceedances decreased from upstream. Highest exceedance values occurred in June. • Lead remains not limiting or very low limiting for all species. TVS correspond with BT criteria. • Every sample continued to detect manganese, but levels are less than A-68. No acute criteria were exceeded. Chronic BT criteria suggests Mn is still limiting for brook and brown and less so for rainbow. TVS would suggest Mn is not limiting with no TVS exceeded. Duration of BT exceedances is about 5-7 months, increasing from A- 68. All exceedances were 650 ug/1 or less over criteria. • Every sample continued to detect zinc, but levels are less than A-68. Brook trout are probably not limited any longer. Both rainbow and brown remain highly limited, more so than TVS would suggest. Brown more chronically limited and rainbow acutely limited. High values are associated in April. Exceedances occurred in all seasons with the most in the summer months. Chronic exceedances were evenly distributed from 150-650 ug/1 over criteria. Acute exceedances were Vz less than 150 ug/1 over and Vi 250-450 ug/1 over criteria. The TVS exceedances represented is a poor average of brook, brown and rainbow BT exceedances, protecting brook but not brown and rainbow. The acute TVS is more stringent than acute BT criteria providing more protection for all species. Segment 4a - Animas from A-72 to Elk Park (Characterized by A-73) The limited sample size at this location minimizes conclusion that can be made Based on the data provided it is inferred that: • aluminum has the potential to be episodically chronically limiting • chronic cadmium toxicity possible • episodic chronic copper toxicity possible • 500 ug/1 Iron criteria (rainbow) likely but not limiting; other species okay • chronic zinc toxicity likely, especially for rainbow, and lesser for brown Segment 4b - Animas River from Elk Park to Junction Creek (characterized bv A- 74 and A75) J Site A-74 is similar to A-73 in number of samples and limited conclusions regarding potential limiting metals. The bullet list below refers primarily to A-75, • Aluminum had a small sample size of only 4 samples. Dissolved or total fraction cannot be discerned. None exceeded 750 ug/1 (acute) or 87 ug/i (chronic). Not enough data to conclude but aluminum is probably not limiting for any species in this segment. • Cadmium was low to not limiting for all species using TVS criteria No BT criteria were exceeded. There were 3 chronic TVS and 1 acute TVS exceedances, low in magnitude and mostly in the spring. Cadmium remained dissolved. - • Copper is low to medium limiting using TVS criteria. No BT criteria were exceeded. TVS exceedances were in the spring, one-month duration every year Copper was mostly in the total fraction. • Iron continued to be detected in all samples but decreased in exceedances The 1000 ug/1 criterion was exceeded 44 times or 30% of the samples above detection, Double that for rainbow criteria of 500 ug/1. Magnitude was not large and spring was the most exceeded season. • Lead reappears at A75 versus upstream, primarily in the total fraction. Acute BT or TVS was not exceeded, chronic criteria was exceeded but not limiting All exceedances were 25 ug/1 or less over criteria. • Manganese continued to be detected in ail samples but BT and TVS criteria were not exceeded. • Zmc does not limit brook; low frequency and duration at chronic levels might limit brown and chronic levels highly limit rainbow. Spring is the most exceeded season Exceedances occurred every year, all year with May and June providing occasional reprieve perhaps due to dilution. Acute magnitude was fairly large but chronic magnitude was not. Chronic TVS over-protects brook and brown but under protects rainbow. Acute TVS correlates with acute BT criteria regarding protection. Summary of Toxic Exceedances for Each Metal at Seven Stations The following schematics, Figures 6.2 - 6.8, are presented to summarize the results of analysis for each of seven metals, Al, Cd, Cu, Fe, Mn, Pb, and Zn at seven reference VI-20 locations. The report contains more detailed tables, graphs, and text explaining the number, range, magnitude, seasons, of exceedances. KEY TO SCHEMATICS All numbers refer to text Abbreviations: B = Brook Trout BT = Biological Thresholds Chr = chronic Diss - dissolved Det = detection limit Eval = evaluated Exc = exceedance F = fall H = high L = Brown Trout M = medium Mag - magnitude R = Rainbow Trout S = summer Spr = spring SS = Stream Standards W = winter Figure 6,2. Aluminum Toxicity Summary (Note: criteria across species is the same, BT and SS same except BT accounts for pH<7, pH>7 SS does not) ✓ 122 122>det, 72 diss, 63>80% diss, dissolved ✓ 107,55>det, 34 diss, 10>80% ✓ 122/128 clir and acute exc, exc all the time, every year diss, Total 2/3 of time ■/ exc distributed across all seasons, summer and fall highest y 750 ug/1 criteria not exc Chr magnitude is large, 57% values 4000-6000 ug/1 over ✓ BT 2 exc 87 ug/1 criteria criteria, 30% 1000-2000 over criteria ✓ SS 26 exc 87 ug/1 criteria ✓ Acute magnitude 34% values 4000-6000 over criteria, 50% ✓ SS exc mostly occur in fall, 2000-4000,21% 1000-2000 over criteria spg All species II limited, acute exc, all year, every year ✓ In fall values 1-20 ug/1 over 87 ug/1 criteria ✓ In spg values 20-40 ug/1 over 87 ug/1 criteria ♦ BT suggests A1 not limiting ♦ SS suggests A1 is L-M ✓ 125,79>det 79 diss, l>80%diss, Total limiting S A1 total fraction dominate unlike Cement Cr □ SS and BT do not corr with 87 S 50/83 exc 87 ug/1 criteria ug/1 criteria due to pH ✓ 25/83 exc 750 ug/1 criteria consideration in BT criteria •S Low exc in Sept/Nov, hi in Nov ■S Most exc in winter then spg both chr and acute S Magnitude for 750 ug/1 criteria, 60% 14000- 2250 over, 20% 100-700 over v" Magnitude for 87 ug/1 criteria, 24% 1900-3000 over, 8% 700-1400 over, 68% 100-700 over 128,70>det, 45 diss, 0>80% diss, total S HF, duration 6-7 months, hi mag for both BT 36 exc of 87 ug/1 criteria chr/acute SS 37 exc of 87 ug/1 criteria (diff due to BT ■S Freq, dur, < Cement Cr, mag > Cement Cr, total consideration of pH) vs diss BT/SS 6 exc of 750 ug/1 criteria ♦ II limiting all species Chr exc low in Nov, hi in March □ SS corr w/ BT criteria-ie BT consideration of Acute exc low in Feb, hi in March pH doesn’t make as much difference to A1 All exc, most exc winter, then sprjJ toxicity, the low pH is more limiting by itself 87 ug/1 criteria exc magnitude, all values were <1000 ug/1 over, Vi were < 700 ug/1 750 ug/1 criteria exc magnitude, 3%>1500 ug/1 over, 57% 100-800 ug/1 over, 35% < 100 over A1 level, extremes, freq, dur, mag < CC-48, MC-34 v'' 4 ,2>det, 2 diss, l>80%diss, Vi diss, ‘A M limited to all trout species total, not enough data to conclude SS and BT 87 ug/1 criteria may result in S No exc of 750 ug/1 criteria different conclusions if don’t consider pH v' 1 exc 87 ug/1 criteria, in June v' mag of exc almost 2 x greater than 87 ug/l-suggest potential for more exc ♦ ? limited, not enough data to conclude, hyp 5 ,2>det, 2 diss, 0>80% diss, ?diss ✓ 4, l>det, ldiss, 0>80% diss, ?diss or or total total, only one sample No exc 750 ug/1 criteria ✓ No exc of 750 or 87 ug/1 criteria but 1 exc 87 ug/1 criteria, in June only one sam plodet, 4 total mag of exc 4 x greater than 87 ✓ Not enough data to conclude, can infer ug/1 criteria-suggests potential for levels, freq, dur all < upstream. more exc Not limiting to trout species ? limited, not enough data to conclude, hyp ✓ 130,130>det, 127 diss, all>80% diss, S 6 , 3>det, 3 diss, all>80%, dissolved dissolved ✓ No BT criteria exc S No BT criteria exc SS 3 chr exc, 1 acute exc 4 - S SS 2 chr exc, no acute ✓ May, June, March exc months v' June/July hi, May low exc ✓ Magnitude exc small Baker Br ♦ Not enough data, but potential for ♦ L to not limiting for all species criteria exc a SS might be stringent for chr/acute □ Not enough data, possible SS are relative to BT criteria stringent V 171,170>det, 130 diss, 118>80%diss, mostly Diss S no SS, brook most sensitive V B mostly chronic toxicity conditions ■/ L/R when exceed is of acute level ✓ 2 4 2 ,188>det, lSldiss, v' Exceedances all year, every year (IIP/HD) 56>80% diss, Diss 30% of •/ S pg, summer greatest exceedances for chr time ✓ B most sensitive trout ■/ Fall is acute highest season ■/ BT 16 chr exc, 0 acute ♦ B chronic M-H limited SS 32 chr exc, 13 acute ♦ L acute H limited V May/June lowest -dilution? ♦ R acute H limited ✓ Spg into Summer greatest exceedances ✓ Magnitude small, 85% only ...... 5 ug/1 or less over criteria • •« ♦ B chronic L-M limited ✓ 247,204>det, 181 diss, 65>80% ♦ L L limited diss, diss Vi of time ✓ ♦ R L limited B/R chronic exceedance same A68 □ SS more conservative than ■/ L/R acute exceedance same BT, both chr & acute v SS match BT for L when B more sensitive s BT max in May, min Oct-Jan s SS max June/May, min same s BT/SS, chr & acute spg, summer then fall most exceedances ■/ B 9-10 month duration, 15-55 ug/1 v' 7 2 ,47>det, 41 diss, 11>80% diss, not over chr criteria 35 ug/1 over acute consistently diss or total ✓ L/R < B, L 5 ug/1 over chronic v' No L toxicity critieria, R 5 ug/1 overacute criteria •/ BT chr exc for B/R equal SS chr ♦ B II limited ✓ Acute BT exc=0, SS=7 ♦ L L- M limited v' BT low/hi in Feb/Jan, SS low/hi in ♦ R M-H limited May/April a SS protect L, B more sensitive and v' Winter most exc then spg more likely to be present v' B duration 1-2 months, 5-15 ug/1 over criteria ♦ B M-H Limited ♦ L not limited ♦ R M-H limited ♦ SS M-H limited □ SS chr =BT chr, SS acute more stringent V 4 ,2>det, 2 diss, XA diss?? S 1 SS, 0 BT exceedances S not enough data for pattern, conclusions or inferences NeedleCr r ’*’ ✓ 4 , 3>det, 3 diss, dissolved? v' No SS or BT exceedances ■J not enough data for pattern, conclusions or inferences ✓ 133, 129>det, 129 diss, 21>80% diss, mostly total ■/ No BT exceedances •/ 11 chr SS, 2 acute SS exceedances A75 •/ Occurred April-July, apparently no dilution effect but addition Baker Br *7’ v' Exceedances occurred every year, about 1 month duration ♦ SS say L-M limited □ SS more conservative than BT Figure 6.5, Iron Toxicity Summary (Note, Fe chronic and acute BT and chronic SS are 1000 ug/1 except for rainbow chronic BT of 500 ug/1) S 171,110>det, 91 diss, 49>8Q% diss, Vi total, Z2 diss S No acute exc ✓ 218,29>det, 24 diss, 0>80% S No chronic BT B exc diss, 34<10%, total most of S L only 2 exc time S R 99 exc, low in June, hi in Aug ✓ No acute BT or SS exc ♦ B/L L limited ✓ 2 B, 10 R chr BT versus 7 chr SS exc ♦ R H limited, every yr, fall the most, duration 1 ✓ month, 5-15 ug/1 over criteria so not much BT Feb/March low/hi ✓ SS July/ April low/hi ✓ Spg, summer equal exc, winter/fall < V Magnitude < 10 ug/1 over criteria ♦ B L limited L not limited ✓ ♦ R L limited 209,29>det, 24 diss, 3>80% diss, - . ( 5 p total ♦ SS L limited ✓ No acute BT or SS exc □ SS corr w/ BT exc /& ✓ B2, L3, R9 BT chr versus 6 SS exc ✓ Low Aug/Nov, hi Nov (rain?) Equal exc in spg, summer, fall ✓ Magnitude mostly very low ✓ Events few, short durationd but some 50-60 ug/1 over criteria so potential hi event ✓ 150,6>dct, 0 diss, 0>80% diss, total All trout L limited ✓ No acute BT or SS exc SS corr w/ BT ✓ BT chr exc same for B and R, SS had 2 exc ✓ Low BT in Aug, SS in June ✓ Hi BT and SS in Aug ■/ Summer most exc season ✓ Exc not freq, low duration, every 2-7 yrs ✓ Magnitude < 5 ug/1 over criteria, but hi event 30-40 ug/1 over ♦ All species L limited A73 □ SS corr w/ BT ✓ 5, 0 det, 0 diss E,k Cr ✓ 0 exc BT or SS ✓ Not enough data to conclude, see patterns, etc. Needle Cr ✓ 5, l>det, 1 diss was 100%diss of total ✓ 0 exc BT or SS ✓ 80,8>det, 8 diss, 1>80% diss, total ✓ Not enough data to conclude, see ✓ No acute BT or SSexc patterns, etc. ✓ 1 BT R exc, 3 SS exc ✓ June hi/low and summer most exc A75 ✓ All 25 ug/1 over criteria ✓ Pb reappears here relative to A73, A74 Baker Br but not toxic, but right conditions could be (storm event) S 169, 169>det, 127diss, 125>80%diss, dissolved v' 247, 247>det, 212diss, 200>80% diss, / B 38 chr exc, no acute criteria Dissolved / L 168/169 dir exc and 156/169 acute J B 36 d ir exc, no acute criteria J R 168/169 both dir and acute exc v' L239 direxc, 81 acuteexo v* Low and hi for B is Nov S R 241 chr exc, 186 acute exc ■ / lx>w for U R is June, hi is Nov S SS 147 dir exc, 146 acute exc S Summer most exc, spg=fall, then winter ♦ BT low in Feb, Jan—R Aug ✓ Mag L, 80% 350-600>chr criteria, all>300 ug/1 S BT hi in May •/ Mag R, 84% 450-850>chr criteria SS low Aug, hi May / Duration >st in spg, some yrs B get 6 months off, exc occur every yr, every month ♦ Exc occur all yr, every yr ♦ D M limited ^ BT dir s=spg, w, f versus SS s, spg, f ♦ L II limited (combination dir/aarte exc) then w / BT acute spg, sum, f=w, versus SS acute ♦ R H limited (mostly aaite exc) s=spg, f=w v' B med F/D ■ f L chr I IF/HD, acute MF/, 7 months ✓ R chr IIF/HD, aaite MF/11 months 238,238>det, 199 diss, 193>80%diss, dissolved ✓ DT 80%L,77%R,55%B mag was 250- Brook conditions not toxic 650 over criteria BT L 145 chr, 17 acute exc / SS 80% 250-450 over dir criteria, BT R 23 5 dir, 106 acute exc 22%>650 over acute criteria SS 137 dir, 136 acute exc ♦ B M limiting BT low/hi May/June chr, March acute low, April acute hi ♦ L II chr limiting, acute M, mag hi, SS low June chr, Feb hi, acute same Measured values >570 ug/1, butno Hardness so not in eval, HD/I IF thus exc even greater, mag, freq ♦ R H limited dir/acute, mag hi, HD/IIF Chr BT summer, spg, fall, then winter, vs chr SS, Spg, □ Chr SS over protects B, way under L/R winter, fall then summer □ Acute SSavg of L/R Acute BT, summer=spg, winter=fa11 vs acute SS, summer, spg, fall, winter ✓ Duration 9-10 months, every yr dir, acute 1 week- lmonth ■/ R same, but acute 5-6 months ✓ Mag dir/acute SS and chr BT bell shaped curve 192, 192>det, 66 diss, 65>80%diss, distribution (50-550 ug/1 over criteria) dissolved ✓ Mag BT acute all <250 ug/1 over B 5 chr exc, no aaite criteria, okay ♦ B not limited, L chronic, R acute limited L 163/171 dir, 39 acute SS chr average of all species, protects B, most of L, not R □ R 171/171 dir, 114 aaite a SS acute, protects B, stringent for L, okay for R SS 133 chr, 133 aaite B low in March, hi in April L/R & SS low in June, hi in April All seasons are exc, BT/SS chr /acute most in summer Chr R/ L even dist of mag 150-650 ug/1 over criteria / 4, 3>det, 3 diss, dissolved Acute R/L V4 <150 ug/1 over, M 250-450 ■ / B no chr exc, no acute criteria ug/1 over BT dir L 1 exc, no acute R/L HD, HF exc BT dir R 3 exc, no acute B not limited SS chr 3 exc, 3 acute exc R/L II limited, L chr, R aaite June/July hi/low all Chr SS is avg, protects B, less so for L/R Mag L 70 ug/1 over criteria Acute SS is stringent for all specics R 11-220 u/gl over criteria B okay, might be L/R chronic toxicity, fish probably move Chr SS corr w/ BT, acute stringent?, not enough d?ita ■ / 128, 128>det, 128 diss, 89>80% diss, dissolved / B 1 BT chr exc, no acute criteria J L 24 BT chr exc, 1 acute / R 128 BT dir exc, I acute 6 ,5>det, 5 diss, dissolved S SS 85 chr exc, 1 acute B no chr exc, no aaite criteria *'' Low in Aug, hi in May for BT, May both low/hi for SS L 2 chr, no acute / Chr B/L spg most exc, R spr/summer versus SS summer, spg, L 4 chr, no aaite winter then fall SS 3 dir, 3 aaite 'Z Acute all in spg, summer Low may all, hi Oct or June / Exc occur all year, every year, B/R every month but May/June Low freq/dur S Acute R exc was 750 ug/1 over criteria, L was 541ug/l over, SS B not limited, R/L could be but not was 50 and 150ug/l over enough information v' Chr BT for L, 50% values 50 ug/1 over criteria, 36% 50-150 ug/1 Chr SS corr w/ BT, acute SS might be S Increased from upstream but < A72 stringent, not enough data ♦ B not limited ♦ L chronic, low freq/dur limited ♦ R chronic H limited □ Chr SS over protect B/L, under protect R, acute SS corr w/ acute BT The following summary is taken from the CDOW report included as the last section of Appendix 6C. The study’s purpose was to check toxic thresholds of three species of trout specifically for copper and zinc using Animas River water to determine if previously "laboratory determined" thresholds were appropriate specifically for the Animas. An earlier review by the Biology Work Group and the CDOW had determined that these metals in particular required this determination. “Based on Animas River and laboratory toxicity data, brown and brook trout are equally sensitive to the toxicity of copper. Brook trout generally appear to be approximately three times more tolerant to the toxicity of zinc than brown trout. However, during the early spring of 2000 laboratory toxicity tests both species appeared to be equally sensitive to zinc. Cutthroat trout, under similar water quality and temperature conditions, are more sensitive of the three species tested for both copper and zinc. Copper appears to be a metal of concern in 4a, relative to potentially toxic affects on the Animas River. Though dissolved Cu concentrations are generally below levels found to be acutely or chronically toxic in the Animas River toxicity tests (except, as discussed in Appendix 6C), the questionable data collected during the Early Spring 2000) are frequently within in a factor of two to three of levels found to be chronic in Animas River water and at levels that generally equal or exceed EPA acute and/or chronic criteria. Zinc is also a metal of concern in 4a but probably less so than copper. Dissolved zinc concentrations in the Animas River (even though they exceed acute and chronic criteria) are generally less than levels found to be acutely or chronically toxic to either brown or brook trout. Total metal concentrations for other toxic metals are high for aluminum, cadmium, iron, manganese, and lead. However, dissolved concentrations of these metals are generally below toxic levels, except for cadmium. Dissolved cadmium concentrations frequently approach or exceed potentially toxic levels for both brown, brook and cutthroat trout. Where mortality did not provide a clear distinction between LOEC (low effect concentration) and NOEC (no effect concentration), the CDOW took a conservative position in estimating sub-chronic “effect” and “no-effect” toxicity levels. The water used in the tests was just a “window” of the water in the Animas. Also, during the spring testing periods, high flows and much higher sediment loads were observed in the river during the afternoon when air temperatures had increased. It is likely that the metal concentrations were higher during the afternoon than were measured in water collected in the early morning. With the 5 to 9 day sub-chronic test duration, mortality was the only effect that could be measured. Generally, reduced growth is a more sensitive measure of adverse chronic effects. Consequently, a more sensitive indictor of harm was not assessed. Recommendations in regard to the study objective are that attempts be made to develop water quality conditions capable of supporting a brown and/or brook trout fishery below VI-29 Silverton. Because of its higher sensitivity to metals cutthroat trout are not recommended for the Animas River below Silverton. To attain a viable fishery, cleanup of point and non-point sources of metals in the Animas River basin at Silverton should achieve the following target levels of copper and zinc based on the Animas River toxicity tests. These levels need to be met during spring runoff, the period of lowest water hardness and greatest vulnerability of brown and brook trout." Copper levels needed to support brown or brook trout in the Animas River: Brown or Brook Trout: 20ug/liter Zinc levels needed to support brown or brook trout in the Animas River: Brown Trout: 250 ug/liter or less Brook Trout: 700 ug/Htcr or less Cadmium levels needed to support brown or brook trout in the Animas River based on laboratory and literature values (these were not tested using Animas River water) : Brown or Brook Trout: 1.2 ug/liter______This table is from CDOW report in Appendix 6C. Although three seasons and a total of five weeks were spent in the field completing these tests, conditions were encountered that made results less than conclusive. This is normally the case for any scientific experiment with many variables. The tests were not designed to provide conclusive evidence but rather to supplement existing information. The conclusions differ little from previously determined thresholds used throughout the State of Colorado. Table 5.2 of the Appendix 6C, Biotoxicity Report, lists the final biological thresholds used for the UAA. Seasonal and temperature variations affect biological thresholds but are not quantified. It is possible that thresholds are higher when temperatures are less. This may partly explain why brook trout are able to withstand the acutely toxic conditions in Segment 3 a described in Chapter IX - Limiting Factors Analysis. OTHER STUDIES AND FACTORS SIGNIFICANT TO AQUATIC BIOTA There are several factors and findings from studies that are either not covered in any other report included in this UAA or need to be highlighted in the UAA. These factors and findings cross over physical, chemical and biological components of the ecosystem. Dissolved Metals versus Total Metals Metal values are usually reported as either dissolved (filtered) or total (not filtered). The total fraction includes both the amount of dissolved metal and the amount complexed with other compounds to make a solid. The "dissolved" fraction is obtained by using a 0.45 micron filter which filters out the metals that are complexed, that is the solid particles larger than 0.45 microns. This dissolved fraction is in the form that generally, but not always, has the most potential to cause toxicity for an organism. Generally dissolved, uncomplexed metal ions are more readily assimilated by organisms than the complexed forms (Spraque, 1985). Typically metal samples are preserved in the field with nitric acid, which digests some of the complexed metals in the total fraction (also may dissolve any particles smaller than 0.45 micron in the filtered sample). Samples that do not undergo any further digestion with nitric acid, whether filtered or unfiltered, are referred to as "acid leachable" fractions. When metal samples, such as iron, are further digested with nitric acid before laboratory analysis (complete digestion) the results are referred to as a "total recoverable" fraction. Dissolved metals throughout the UAA refer to acid leachable fractions. Results for iron are total recoverable fractions. Unlike most other metals, aluminum appears to be more toxic in the low molecular weight polymer forms than the dissolved form. Recent evidence suggests mortality below pH 5, where the A1 is predominantly dissolved, is due to low pH toxicity not aluminum toxicity (Playle, et al. 1988). At or near pH 5 the low molecular weight polymers that form result in ionregulatory toxicity (Playle, et al. 1988 ). These occur more often at cold temperatures (2 degrees Celsius), like in the Animas, than at warm temperatures (25 degrees Celsius) (Lydersen, et al. 1990). Not until pH 6.5 is most of the aluminum in the oxidized form (Schemel, 2000 personal communications). After a short duration and/or as pH increases the polymers become higher molecular weight forms that are no longer as toxic (Witters, et. al., 1996) but, in high concentrations, can result in asphyxiation of fish by covering the gills (Playle, et al 1988). Stream standards and biological thresholds still focus on the dissolved fraction however. Fish Recruitment Lack of continuous populations for recruitment purposes could historically and currently limit the recovery potential of a community. If for any reason a specific population (in a stream segment) was stressed to the point of “extinction”, the population would not recover if there are no other proximate populations to move in, whether the stress was human or nature caused. Precipitates and Colloids as Toxicants Metals in river systems typically can move between dissolved, colloidal, and other complexes. They move between the water column and bed sediments through processes including sorption, mineral precipitation, photoreduction, and biological interaction (Church, 1997). Ultimately metals are separated from the water and are carried as suspended colloids or sediments, which eventually settle to become part of the bed sediments or become trapped by algae and other stream microbes. In the Animas River metals are available in both dissolved and particulate/colloidal forms. Metal precipitates consist predominantly of iron and aluminum hydroxides with volumetrically minor amounts of trace metals (e.g. Cu, Cd, Zn) sorbed to their surfaces (Schemel, 1999). The precipitates generally form in a downstream direction as pH rises. They accumulate during low flow, particularly between A72 and Baker's bridge (Church, 1997) but can be re-mobilized during high flow events. In addition, metal oxide precipitates are considered relatively unstable and may become re-dissolved if acidity is increased. Pore space is presumably reduced by accumulated colloids, however Anderson (Chapter VI, Appendix 6B) found little evidence that pore space was so occluded as being a limiting factor for macroinvertebrates. Church, 1997, suggests that the colloidal component of the bed sediments dominates the bed sediment chemistry. Besser, 1998, found that metal concentrations in periphyton samples (which consisted of algae, associated microorganisms, and mineral deposits) strongly correlated with metal concentrations in the fine sediments. Iron and aluminum colloids may have substantial amounts of copper and zinc sorbed to their surfaces. Clements, 1998, found colloids in Segment 4a to contain elevated concentrations of copper, cadmium, lead, zinc, iron, aluminum, and manganese. He states that "the high concentrations of metals associated with the colloids may be toxic to macroinvertebrates and fish via food-chain accumulations". This has not been confirmed however. (See Bioaccumulation) Although the streambeds of the Animas contain high amounts of metal sulfides and the more reactive metal oxide precipitates, there is no definitive evidence that these higher than normal metal concentrations are directly toxic. Clements, 1999, exposed high concentrations of colloids collected at A72 to a sensitive species of mayfly (Baetis tricaudatus) in a five day toxicity test. There was little evidence of toxicity. Unfortunately the experiment did not adequately duplicate important conditions present in the Animas (colloids were not kept suspended), which leads to questionable results. Besser (2000) tested the toxicity of fine sediments on two species of benthic invertebrates (amphipod and midge sp.) but found only minimal toxic responses. He concluded that "The toxicity observed in sediments from the upper Animas River watershed were associated with concentrations of labile Fe/Al oxides in sediments and to concentrations of aqueous Fe in sediment pore water." (LC50s were established for zinc in fathead minnow and amphipods for surface water column concentrations only [Besser and Leib, 1999]). Streambed Metal Sulfides Church, 1997, points out that over 50 percent of the zinc in bed sediments in the Upper Basin is in the form of sphalerite (zinc sulfide), the source of which is from erosion of vein material and mill tailings that have been dumped into the river. Sulfides of lead, copper, iron, and other metals are present as well. Metal sulfides are considered relatively stable but this writer is unaware of any attempts to determine speed in which these sulfides might become oxidized in the aqueous environment. Bioaccumulation Concentrations of metals in whole tissue digestion samples were measured for trout in Segments 4a and 4b of the Animas River by the Bureau of Reclamation, 1992. In another investigation the U.S.G.S. Biological Research Division (Besser, 1999) looked at the accumulation of metals in trout, periphyton, and invertebrates. Bioaccumulation of metals in trout and macroinvertebrates was studied in Segment 4a by Besser, 1999. "These results indicate that exposure of predators such as brook trout to metals via metal-contaminated diets differs from waterborne exposure due to processing of metals through the stream food web. Chronic metal exposure of both fish and invertebrates of the upper Animas Watershed, which occurs via both water and diet, may result in impacts at sites where water is not acutely toxic," In a related presentation, Besser, 1998, concludes that "metal concentrations in the biota of the upper Animas River watershed are comparable to those associated with adverse effects on fish and invertebrates in other mining-impacted streams". There is no evidence provided as to the source of accumulated metals (food chain, colloids, water column), nor, more importantly, have thresholds of any detrimental effects been determined Dead, dying, or unhealthy fish have not been found in recent years. Bioaccumulation may impact the longevity and condition of life by reduced physiological functions but this has not been demonstrated. Given the minimal evidence available, this report considers bioaccumulation as having no to low potential as a limiting factor in 3a and 4a and of no potential where dissolved metal toxicity currently precludes most aquatic life (Segments 2, 7, 8, 9). Precipitates as Habitat Stressors (Smothering Stream Substrates') Results of macroinvertebrate liter decomposition experiments conducted in the Animas and similar watersheds of Colorado with varying concentrations of dissolved metals, colloids, and acidity provides some important insight into the relationships of colloids, pH, and dissolved metal concentrations. Niyogi, 2001, tested the hypothesis that biodiversity has a low threshold of response to stress, whereas biomass and function are stable or increase under low to moderate stress and decrease only under high stress. He ran decomposition experiments using streams with varying levels of mine drainage as chemical (using dissolved zinc as the indicator) and physical (deposition of metal oxides) stressing agents. He found diversity was low in streams with low pH or high concentrations of dissolved zinc. "Biomass and production were high in streams with only chemical stress, but were usually depressed in streams with physical stress caused by metal oxide deposition. Stream sites where aluminum oxides were being deposited usually had little or no algal biomass. The rate of metal oxide deposition, presence of aluminum oxides, and pH together explained 60% of the variation in biomass. Net primary production was highly correlated with biomass, and had similar responses to stresses from mine drainage. Overall, chemical stresses (low pH, high concentrations of zinc) did produce the hypothesized trends (decreased biodiversity) in ecosystems under stress. Physical stress (deposition of metal oxides), however, decreased biomass and function even at low stress, contrary to the original hypothesis. Thus, the nature of ecosystem response to stress may differ for chemical and physical stresses." Based upon extensive experimentation in several locations within the Animas and other mine impacted streams in Colorado, Niyogi (1999-personal communication) believes that decomposition rates are less affected by increased zinc concentrations than the deposition of metal oxides (aluminum and iron precipitates). As a local example of this, his findings show a relatively faster rate of decomposition in Prospect gulch, characterized by generally clear water, low pH, steep gradient, little oxide deposition and high zinc concentration, than in Cement Creek which is characterized by murky water, slightly higher pH, lower gradient, similar zinc concentrations. Physical stress can be minimal at low pH because metal oxides remain dissolved. Chemical stresses then predominate. Decomposition rates may be fast due to primary production and fungal activity but few macroinvertebrates would exist. Decomposition was slower in Cement Creek where deposition of metal oxides tended to be more prevalent. In conclusion, it appears that the deposition of colloids can interfere with decomposition rates of liter, by macroinvertebrates, and the primary productivity of algae. Biodiversity is limited as well as biomass and ecosystem function. Acidity and Alkalinity (as measured by pH units) All evidence indicates that acidity is a primary limiting factor for most of Segments 2, 7, 8, and 9b, Water pH is typically at 5.0 or lower for long duration in these segments, resulting to toxicity to all species of trout. pH also influences the physical state of most metals and the ability of primary producers and many benthic macroinvertebrates to survive and function (Niyogi, 2000). Aluminum, iron, and copper have been shown to move in and out of the dissolved phase as the pH of streams increases or decreases on its journey through major source loading areas. Accordingly, one can expect to find toxic conditions gaining and receding from these metals, depending upon the pH as one progresses downstream. Toxicity of metals reflects the seasonal distribution of acidic conditions as well. Although low alkalinity would not be a limiting factor in itself, its extremely limited availability, particularly in Cement and Mineral creek has a profound effect on pH. Above normal precipitation acidity, combined with exposed soils and rock outcrops containing disseminated iron pyrites, and a lack of alkaline buffers results in an acidic environment reflected in both surface and ground waters. Anchor Ice Anchor ice develops on the stream bottom along with frazil ice (floating ice like in a slushy drink) when the dark colored stream substrates lose radiant heat at 0 degrees Celsius. Conditions that maximize anchor ice production usually occur in late fall and over the winter during long periods of clear night skies, low precipitation and freezing air temperatures. First, frazil ice forms and floats in the river until it “gloms” onto other frazil ice, rocks and or debris. Once a chunk of frazil ice sticks to an object it becomes a magnet to “stick” more floating ice. One form in the evolution of frazil ice is anchor ice. Anchor ice is frazil ice that has crystaline structure that adheres to projections, especially on the substrate. These projection objects provide an adhesion surface much stronger than a flat muddy bottom where the heat conducted from the ground prevents rapid loss of heat. The adhesion is so strong that when the anchor ice is released it takes the substrate with it, like a big slag of cement. Lots of active anchor ice can have a detrimental effect to the aquatic habitat requirements the substrate provides. Anchor ice can be a one in 5, 10 or 100 year impact or in some locations occur frequently enough it precludes a healthy functioning macroinvertebrate community. Anchor ice was considered to be a marginal limitation due to the available recruitment macroinvertebrate communities. Anchor ice probably does occur but is not the limiting factor inhibiting aquatic life in the mainstem of the Animas and major tributaries. Angler pressure Angler pressure has increased in response to the improved fisheries at Elk Park and Segment 3a. This must be considered when using monitoring results to determine remediation effectiveness. When adults are periodically removed recruitment becomes more important, whether natural or by stocking. Tributaries and the Animas mainstem above Baker's Bridge have not been restocked in eight years Incomplete Studies Due to time constraints there are several studies that pertain to this biology chapter that cannot be included at this time. Fieldwork has been completed but the data is not fully analyzed and available to the ARSG and/or awaits further review and publication. In particular this includes the following two important investigations. • John Besser, and others of the USGS Biological Research Division, have recently completed biotoxicity experiments at several locations within the Upper Animas basin. These experiments include biotoxicity tests using brook trout, flathead minnows, and two species of macroinvertebrates. Preliminary results have been included in the UAA as personal communications since the main text is yet to be published. • Appendix 6D, the Hydrosphere Report, is being listed as an appendix, however, it remains unavailable at this time, The report is a detailed bioassessment of Segment 4a. The U.S. Forest Service contracted this assessment to be completed under the direction of the Biology Work Group. A draft report completed in June, 1999 was returned to the contractor in need of several revisions and edits. Unfortunately a final report is not yet available. When it becomes available it will be sent alone to complete this chapter. The assessment consisted of three major parts, each containing several complex tasks. Major components include 1) water chemistry data collection, analysis, and creation of dissolved speciation and loading models, 2) a series of in-site manipulative benthic macroinvertebrate experiments using various substrates and conditions within Segment 4a and tributary reference reaches to attempt to determine if physical habitat is more or less limiting than the water chemistry components, and 3) an evaluation of benthic macroinvertebrates physical habitat conditions. Principle investigators have been Ann S. Maest, William H. Clements, and William Walsh. Some results of Mr. Clement's and Mr.Walsh's work have been mentioned in the UAA, however these need to be considered as preliminary, unpublished results subject to change. THREATENED AND ENDANGERED SPECIES CONSIDERATIONS Few threatened or endangered species are known to reside in the Upper Animas Basin. Two such species are the goshawk (Accipiter gentilis) and Boreal Toad (Bufo borealis). Lynx have recently been reintroduced into the area and the Fritillary butterfly can be expected above timberline. There are several rare plants including disjunct species of mosses, one of which is associated with the acid conditions of naturally occurring iron bogs in Mineral Creek. Several rare and/or endemic higher plant species exist in the San Juan Mountains. Currently there are no known aquatic threatened or endangered species in the Upper Animas watershed. Nevertheless, remediation work, which often requires terrestrial impacts, displacements and potential impacts to aquatic environments should only progress after an inventory of threatened and endangered species is taken and precautions are taken to minimize impacts to adjacent wetlands and aquatic systems. REFERENCES Besser, John M., Brumbaugh, William, Church, S.E., and Kimball, B.A., 1998. Metal Uptake, Transfer, and Hazards in the Stream Food Web of the Upper Animas River Watershed, Colorado, U.S.G.S. Open File Report 98-297, p. 20. Besser, John M., Nimmo, Del Wayne R., Milhous, Robert, and Simon, William. 1998. Impacts of Abandoned Mine Lands on Stream Ecosystems of the Upper Animas River Watershed, Colorado. U.S.G.S. Open File Report 98-297, p. 15. Besser, John M., and Leib, Kenneth J., 1999. Modeling Frequency of Occurrence of Toxic Concentrations of Zinc and Copper in the Upper Animas River. Proceedings of the Technical Meeting, Charleston, South Carolina, March, 1999, p 75-81. Bureau of Reclamation, 1992. Whole Tissue Digestion Analysis of Fish Collected in the Animas River. Durango Field Office, Durango, CO Church, S.E., Kimball, B.Z., Fey, D.L., Ferderter, D.A., Yager, T.J., and Vaughn, R.B., 1997. Source, transport and partitioning of metals between water, colloids, and bed sediments of the Animas River. Colorado; U.S. Geological Survey Open-File Report 97 -151, 135 p. Clements, William 1999. Upper Animas River Biological Evaluation Draft Final Report, prepared for San Juan/Rio Grande National Forest, U.S.D.A. Forest Service. Lydersen, Espen, Salubu, Brit, Poleo, Antonio B.S., and Muniz, Ivar P. 1990. The Influences of Temperature on Aqueous Aluminium Chemistry. Water, Air, and Soil Pollution 51: 203-215. Niyogic, Dev K, 2000. Litter Breakdown in Mountain Streams Affected by Mine Drainage: Biotic Mediation of Abiotic Controls. Accepted for 2001 publication in Geological Applications. Resh, V.H. and J.K. Jackson. 1993. Rapid assessment approaches to biomonitoring using benthic macroinvertebrates. Pages 195-233 in D.M. Rosenberg and V.H. Resh (editors). Freshwater biomonitoring and benthic macroinvertebrates. Chapman and Hall, New York. Schemel, L. 2000. Personal email communications Oct. 16, 2000 from Schemel (USGS) to W. Simon concerning sampling results on the states of aluminum and iron in Mineral Creek. Spraque, J.B. 1985. Chapter 6: Factors that modify toxicity. In: Fundamentals of aquatic toxicology. (G.M. Rand and S.R.Petroce!li, eds.) Hemisphere Publ. Corp., Washington. 124-163pp. Tsivoglou, E. C., S. D. Shearer, J. D. Jones, C, E. Sponagle, H. R. Pahren, J. B. Anderson, and D. A. Clardk. 1960. Survey of interstate pollution of the Animas River (Colorado-New Mexico) II. 1059. Surveys. U. S. Public Health Service, Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio pp. 153 (Mimeo). Witters, H.E., S.V. Puymbroeck, A. J.H.X. Stouthhart, and S.E.Wendelaar Bonga. 1996. Physiochemical changes of aluminium in mixing zones: Mortality and Physiological Disturbances in Brown Trout (Salmo trutta L.). Environmental Toxicology and Chemistry;, Vol. 15, No. 6; 986-996. APPENDIX 6A FISHERIES REPORT Bound in Separate Cover APPENDIX 6B MACROINVERTEBRATE REPORT Bound in Separate Cover APPENDIX 6C BIOTOXICITY REPORT Bound in Separate Cover APPENDIX 6D RESERVED FOR THE HYDROSPHERE REPORT CHAPTER VII - METAL LOADING PROCESSES High metal concentrations are impairing potential uses in the Upper Animas Basin. Where do the metals come from and why is there so much metal in the Animas as opposed to other watersheds? Are these high metal concentrations natural or caused by human activity? This chapter and the next chapter address these important questions. Most of the Upper Animas Basin lies within the caldera of an old volcano. Volcanic activity is the initial geologic process for deposition of high concentrations of metals in the ground, These high concentrations attracted miners to the region. Few places in the country have seen as much mineral enrichment over such a large area. Physical, chemical and biological processes cause the metals to dissolve and move into streams. Human activities such as mining, road building, development, and grazing can accelerate the natural processes. Thus, the sources of high metal concentrations in the Basin are a combination of both natural processes and human activities. NATURAL PROCESSES Geology Metal loading processes are directly related to the geology in the Animas River watershed. Sources of metals, both natural and human-related, can readily be predicted by determining the locations of rock types where metals are present. Here is a short description of the Basin geology provided by Bruce Stover of the Division of Minerals and Geology. A more detailed version is in the Appendix 7A. The Animas River headwaters drain the Silverton Caldera, a Tertiary age volcanic center on the western margin of the regional San Juan Volcanic Field. In Oligocene through Miocene time, the Silverton Caldera was a focus of repeated volcanic eruptive activity. Hundreds of cubic miles of ash flows and lava were erupted upon a surface of older Paleozoic and Mesozoic sedimentary rock, and Precambrian metamorphic and igneous basement rocks. Through the middle Tertiary, an extensive, thick volcanic complex was formed, encompassing the present Animas River watershed. During periods of volcanic quiescence, retreat of magma from beneath the domed-up center caused widespread subsidence and subsequent collapse of a roughly ten-mile-diameter ring-shaped caldera within the larger volcanic field. Subsequent periods of eruptive activity each caused renewed uplift and doming of the caldera, followed in time by subsidence^ along the bounding ring-fault fractures as volcanic activity waned. These repeated volcanic episodes formed marginal ring-fault fractures, associated breccia pipes, and swarms ot faults tangential and radial to the margin of the volcanic center. Following cessation of volcanic activity, ground and surface waters began infiltrating and circulating in the cooling mass of volcanic rock. Heat from the cooling magma below set up broad, regional convection systems, circulating hot hydrothermal fluids through the subsurface for millions of years. These fluids chemically altered the original rock mass, and became enriched in metals derived from the volcanic and surrounding pre-volcamc country rock. Eventually, mineralizing solutions reached threshold geochemica temperature-pressure conditions, leading to deposition of several types of rich sulfide ores containing silver, lead, zinc, copper, and gold. The sulfide ores were prefererrtially deposited within and around the existing fissures, faults, and breccia pipes formed millions of years before. As a result, much of the rock in the Silverton Caldera complex is highly mineralized and hydrothermally altered, particulary along the margins of the caldera, and in the vicinity of major fissure vein systems. Through the late Tertiary and to present day, regional uplift and subsequent erosion of the Colorado Plateau has cut deeply into the volcanic pile. Thousands of feet of overlying rock have been stripped away, revealing the roots of the volcanic center Canyons around the margin of the caldera, such those cut by the Animas and Uncompahgre Rivers, have reached the underlying strata, exposing much older Paleozoic and Precambnan rock beneath the volcanic deposits. The Animas River watershed drains roughly three-quarters of the total extent of the Silverton Caldera. Extrusive sequences of volcanic ash-flow tuffs and flow breccias, and dacite-to-rhyodacite lava flows and domes underlie ^ essentially the entire watershed. These rocks belong to the Silverton Volcanic series, and underlying San Juan Formation. The Silverton series has been farther subdivided into mapable formations in the Silverton Caldera. On the southern and eastern margins of the caldera, Paleozoic and older Precambrian rock are exposed beneath the volcanic flows. Intruded upward into the volcanic flows within the caldera, but particularly along its margins, are younger stocks, plugs, dikes, and sills of a variety of igneous rock. The high alpine terrain in the Animas River watershed has been deeply scoured and sculpted by glaciers during the past 40,000 years. Mineral Creek and the Animas River flow in deep U-shaped valleys with flat floors, which were scoured along the faulted caldera margins they followed. Tributary gulches head m cirque basins which hosted hanging valley glaciers that joined the main stem glacier hundreds of feet above the present valley floor. During this period, glacial ice extended down valley all the way to Durango. Exposed bedrock outcrop with thin patchy soils covers an estimated 70% of the surface in the basin. Unconsolidated surficial deposits on the valley floors consist of remnant patches and aprons of glacial till, outwash and stream alluvium, and peat and organic bog deposits in wetland areas. Talus, scree, and rock glacier deposits mantle extensive areas of mountain slopes beneath cliffs and outcrops, where they have formed from continuous rock-fell. Debris fans composed of coarse, bouldery alluvium are commonly found at the mouths of steep ravines and tributary streams where they join the main valley. Isolated landslide deposits occur on steep slopes throughout the basin, and colluvial deposits mantle many of the lower valley footslopes below timberline. The volcanic rocks in the San Juan Volcanic Depression were extensively propylitized and altered on a regional scale, prior to sulfide ore deposition. “Propylitic” alteration is a term used to describe a particular type of mineralogic and chemical change that occurs by circulation of aqueous, hydrothermal solutions through the original volcanic rock mass. Propylitic alteration adds carbon dioxide and water resulting in an alternative assemblage of chlorite, calcite, and clays in weakly altered rocks, to epidote, albite, and chlorite in the stronger phases. Propylitic alteration has resulted in a dull green or greenish gray color to virtually all of the volcanic rocks in the Animas River watershed. Subsequent, regional acid-suifate alteration occurs in the Animas River watershed, and can be correlated directly with degraded stream water quality. Rocks near some sections of the structural margin of the caldera and around volcanic breccia pipes in the upper reaches of Mineral Creek and the western margin of Cement Creek have been highly altered by gaseous acid-sulfate and hydrothermal processes. Acid-sulfate processes have subjected the rock to attack and leaching by hot sulphurous gases and solutions moving upward along the structural margin of the Silverton Caldera. These hydrothermal processes have leached many of the minerals and have introduced large amounts of sulphur and metal sulfides. This type of mineralized terrain is readily distinguished from the surrounding regional propylitic alteration by its extensive re yellow colors. Volcanic flows in the Red Mountain area forming the northwestern part of the caldera were so strongly altered and leached that little remains except silica, kaolinite, and sulfate and sulfide alteration products. All minerals that could potentially neutralize acid have been leached out, leaving the quartz-allunite-pyrite alteration assemblage characteristic of the Red Mountain District. Bleaching of the rocks and subsequent surficial oxidation of the sulfides through geologic time has resulted in the brilliant red, orange, and yellow staining which characterizes many parts of the district. Over much of the eastern margin of the watershed, alteration has occurred along vein systems and is not as regionally pervasive as it is in the western half of the watershed. The alteration assemblage is quartz-pyrite-sericite, These alteration zones follow the veins across the headwaters of the upper Animas River. On the eastern side of the basin, the lower degree of alteration of volcanic rock and the presence of propylitically altered country rock provide better acid-neutralization capacity for surface runoff. This geology produces better water quality in the gulches draining the eastern part of the basin, and fish are present in many of the streams. The geology of tributary watersheds in the Animas Basin can be directly associated with observed water quality in the streams draining them. Streams which drain mineralized, acid-sulfate-altered watersheds have been found to have consistently poorer background water quality than streams draining non-altered watersheds. Adit discharges from mines in acid-sulfate-altered areas generally have ^ higher metal concentrations and are more acidic than discharges from adits in propylitically altered areas. In several cases, it is apparent that faults and other geologic structures associated with the mineralized areas may still be functioning as preferential groundwater flow paths, discharging metal-laden groundwater to the surface streams. Figure 7,1 shows the specific areas of various hydrothermic alteration. ^ The acid-sulfate alterations are concentrated in the upper Mineral Creek drainage (Red Mountain) and the western side of the Cement Creek drainage. These areas contribute substantial acid and metal loading, including iron and aluminum from naturally exposed slopes and other metals from enrichment areas exposed naturally or by human activity. Western areas in the Mineral Creek drainage have sustained, extensive Quartz-Sericite-Pyrite alteration and produce large loads of acid, iron, and aluminum. Other highlighted areas show weak sericite, vein-related alteration that also contribute metal loading. Many of these altered areas were mined resulting in substantial metd and acid loading. Prophylitically altered areas have also been sites of substantial mining activity, but the drainage is far less problematic. C13,323 *13,800 37 52*30" 13,657 M M jeJS lA i Howardsville CC48 48'45l ilvcrton 13,370 107 45' 107 37’30" Base from U.S. Geological Survey 0 1 2 3 MILES Silverton, Colo. 1:100,000, 1982. j | I ^ ^ J Altitude shown in feet. 0 1 2 3 KILOMETERS A Streamflow gaging station Hydrothermal Alteration ^ Acid Sulfate Quartz-Sericite-Pyrite (QSP) 0 Weak Sericite, Vein-related QSP Regional Propylitic Figure 7.1 Chemical and Biological Processes The generation of acidic water and subsequent metal loading is caused by certain natural physical chemical and biological processes. Pyrite (iron sulfide) * widely dm— d throughout the Animas Basin. When this sulfide mineral is exposed to oxygen and water, it SS too*sulfuric acid and iron oxides. The acids are then available to leach other metals from sulfide bearing particles. Furthermore, once the environment is acidic enough for certai bacteria, they begin a biocatalytic process, using water, oxygen, and metal sulfides that great y accelerates the release of metals and acids. Oxidation of pyrite releases sulfuric acid, but contributes little in terms of metal content except for iroiT Dissolved copper and zinc originate from the oxidation of vems and other ennched areas of metal sulfides, (e.g enargite, galena, and sphalerite). Aluminum is dissolved as a product of acid weathering of aluminosilicate minerals. This n a hiaher t)H environment by the acid-neutralizing minerals calcrte, epidote and cloride present in propyhtically altered ro c J and by biotic respiration. Carbon dioxide released by plants can raise the pH. The inner caldera has very little acid-neutralizing capacity due to the paucity of propylitically altered host rocks and short growing seasons. Iron concentrations in streams and pH are closely related. pH is a unit of measurement of the quantity of hydrogen ions present. Within the Animas, high iron concentrations are related to the This oxidation reaction is responsible for hvrirneen ions into the aqueous environment. Removing iron can be an expensive process in parts of the Upper Animas Basin because of its abundance, widespread dispersion, and sludge producing properties which requires contained disposal sites. The oH affects the phase of metals, whether they are dissolved or in particulate form Most of the mttals o^concern hf the Animus Basin, except for iron and to some degree aluminum, are thought to be toxic only in their dissolved state. Generally, the lower the pH, the> mon¡ a metal w“ be in the dissolved phase. Relatively small changes m pH can have a strong effect on the phases of in which we find copper and aluminum in the Upper Animas Basra. HUMAN ACTIVITIES THAT CAN ACCELERATE METAL LOADING Anv activity that exposes pyrite to oxygen and water will accelerate weathering and release ttfuric 3 into the environment. Cutting roads in a hillside may open up sulfide ennched areas Heavy »razing may reduce soil cover that can lead to greater acid generation But mining p rlc tic S T p S S r tend to increase exposure of the suffide-rich rock which leads to accelerated acid generation. Early miners searched for enriched areas that had been filled with sulfur and _ metal bea™ 8 fluids The mines exposed sulfide-bearing minerals to oxygen in adits, slopes, and shafts. These working created conduits for groundwater to leach out metais which eventually drains to the surface. Getting nd of water m the workings was and problem in many mines. As the miners dug, much of' the removed material was dumped directly outside of the adits and portals in waste rock piles. In some places, the waste rock piles are relatively benign, containing little pyrite and other sulfide minerals. In other locations, where miners worked pyrite-rich veins, the piles may have a high metal leaching potential. Mine-waste piles rich in metals and acid generating potential may become large loading sources, particularly if they are situated in or near a gulch or stream, or in front of an adit draining acidic water into the piles. Mill tailings are another potential source of metals. High grade ore was processed in mills. After targeted minerals were removed, the material left over was either disposed of in streams, or in later years, into tailings ponds. This material is finely crushed, increasing the surface area that may be exposed to air and water. It is also more likely to contain metals than waste rock piles. HISTORICAL IMPACTS OF NATURAL AND HUMAN-RELATED METAL LOADING There has been an ongoing debate over how much of the metal loading in the Animas Basin is from natural sources and how much is caused by human activities. The amount of natural loading will have some bearing on how much effort should be spent remediating human sources. Precisely separating today’s metal loading contributions from natural sources versus contributions from human activities of the past and present is virtually impossible. We have no water quality data from a time before there was mining in the Basin. However, we can use more indirect methods to at least get a sense of the magnitude of what may be natural and what isn’t. Historical Reports Black (1994) (Appendix 7B) compiled quotes from various reports and newspaper articles about fish in the Animas River beginning in the late 1870’s. There appears to have been good trout populations in the Animas around Durango in the late 1800’s. Fish were stocked in the Animas above Silverton with great success and trout ponds were constructed. Local citizens recognized that trout would not do well in some sections of Mineral and Cement Creek drainages because of the extensive geologic alterations. The accounts do not describe if trout were in the Upper Animas Basin before stocking began, and reviews of literature have been inconclusive as to whether trout ever existed there naturally. There is a waterfall on the Animas River below Rockwood (twenty miles above Durango) that may have been a barrier to fish migrations into the Upper Basin. According to historical newspaper accounts, water quality in the Animas River became significantly degraded throughout the length of the river around the turn of the century. The culprit was mill tailings that were dumped directly into the river above Silverton. One Durango paper continually called for lawsuits and injunctions to shut down the mining industry in San Juan County. Water samples were taken and sent off for testing, but the results are unkno wn. in addition, the Silverton town dump, which included dead horses and sheep, was located on the banks of the river, below the high water mark, Each spring trash would conveniently disappear. Durangoans were horrified by the practice. Of course, Durango was dumping its own raw sewage directly into the river just below their own city. Apparently, the often discussed lawsuits were never initiated. Smelters for the mined ««w ere located in Durango and were the mainstay of the economy. A number of jobs would be lost if the mines were closed. Instead, the Durango City Council decided to pursue other water supply options The city filed on wttfer in the Florida River and brought it over a low divide to town. Today Durango gets about 85% of its potable water from the Florida River. Thepother 15/o is pulled from tte Animas, and that percentage is growing. (Rodgers, 1999 personal comm.) Black’s compilation of articles matches well with that of summary of historical mining and milling practices m San Juan County. .Tone,, distin^ishes between four different mining periods by milling technologies and practices. During the fir neriod 1871-1889 mining was very small scale and only high grade ore was remove . was little milling and hand-sorted ore was generally shipped directly to smelters. Any mined “ =n*. Kgl. pie 0» p.™ «— > " er “ 5 nnt in wacti* rnck niles bv the entrance. Zinc was not accepted by smelters Decaube it was difficult to smelt. Thus it was left behind. Many of these old piles still contain metals that can be leached out by precipitation. Mining production jumped upward significantly during the next period, Tf-rhnolouies such as tramways and electricity for equipment made mining much easier. Sliver L bTse me a Price fl” ed, but were frequently high enough to wairant arge investments. Many lar^r mines^ieveioped drainage problems and portals were constructed to remove water by gravity. Although much of the ore was still hand sorted for high-grade material, low-grade ore went to S up to twelve stamp mills operated in the Upper Basin during this period years. The stamps pulverized the ore producing muddy slimes and sands that were^ The tailinas were disposed of in the river creating Durango s problems The Shorten Standard sight of clear water running in the ditches of Silverton was a f f o X S t “Of lL years the water from Cement Creek has been muddy and lar from attractive owing'to the mill tailings; and ... the ditches (in Silverton) are being filled up and all traces of them removed.” With the mills, low-grade ore was more profitably mined, because most of the ore didn’t need to be shipped. But it also produced much more waste. Both pynte and sphalerite, the zinc ore, were discarded. World War I marked the beginning of a new era Thedemand[for base m sprocketed and flotation mills began to be built in the basm. The flotation mills removeu S s much more efficiently than older methods. It is hard to tell if this technology had positive orNegative S S consequences. A higher percentage of metals could be removed from a ton of ore, but as a result, “bulk” mining began and much more tailings were produced. Technologies for mining hardrock were also improving. Farmers around Durango complained that the tailings vere lining b threatened lawsuits. Public attitudes towards mining and environmental degradation were changing. By 1935, only one mill was operating in the Upper Basin and it opted for a new disposal method -tailings ponds. This way water slowly filtered out and a much smaller proportion of sands, slimes, and metals reached the river. With the exception of some major tailings pond failures at the Mayflower Mill, tailings were no longer dumped directly into the river. But the damage had been done, From 1890 to 1935, an estimated 7,5 million tons of tailings were discharged into the river. They still affect water quality today. In the early mining years, there were hundreds of mine sites. Most were not profitable or were profitable only for a short time. After 1930, only two mines account for 90% of the Animas Basin production, the Shenandoah-Dives (1930-1952) and the Sunnyside (1962-1991). Figure 8.2 shows the estimated mine production levels in San Juan County, From 1900 to 1935, most of this material was dumped into the river in the form of tailings. Figure 8-2 Estimated Min© Production 1871-1991 350000 300000 250000 200000 150000 100000 50000 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 ¡ H TONS Source: Jones, 2000. Sediment Studies Two scientific sediment studies have documented some of the impacts caused by activities described by Black and Jones. Church ei ah (2000) examined metal content of pre-mining and post-mining sediments in a number of localities in the watershed. Vincent et ah (1999) reported on findings in a trench dug across the valley floor of the Animas River below Eureka, downstream from a number of historical mill sites. Both document substantial environmental changes caused by historical mining activities. Church et al. (2000) studied sediments along the Animas from the Upper Basin down to below Durango. The team used geomorphological mapping of pre-mining sediment deposit They cored and dated trees growing in deposits two meters above the current flood plain. The trees gave minimum ages for the deposits. Five hundred sediment samples were taken from over 50 sites representing both pre- and post-mining terrace deposits. Metal concentrations for a number of elements in post-mining sediments were dramatically elevated. Concentrations of cadmium, copper, lead, silver, and zinc were 2 to 20 times greater m the more recent deposits, Even near Durango, fifty miles below the Upper Basin, copper, lead, and zinc concentrations were 2.5 to 10 times greater in post-mining sediments than pre-mining sediments. Church et a l (2000) states, “Analysis of the geochemical data when coupled with both the historical and geochronological record, clearly shows that there has been a major impact by historical mining activities on the geochemistry of the fluvial bed sediments. In 1998 sediment study (Vincent et al, 1999), a trench was excavated across the wide, flat Animas River floodplain downstream from the historical town of Eureka (upstream from Silverton). Mills above the site operated from the late 1380’s to 1930. The exposed sediments were mapped and sampled. Sediments were dated using a number of methods. Buried artifacts from the early mining era were found. Growth rings were counted from old willow roots imbedded in the different sediment layers. Radiocarbon dating was used on roots and peat. The overall deposition of sediments increased rapidly during the milling period. The authors estimated that the natural, pre-mining sedimentation rates were 70 - 700 tonnes per year. Roads, grazing, and logging over the past century may have added a few thousand tonnes more per year. Stamp mills above Eureka from 1900 to 1918 produced tailings in excess of 35,000 tonnes per year. Fine-grained tailings from flotation mills from 1921 to 1930 were produced at a rate of 150,000 to 330,000 tonnes per year. All of the tailings were discharged into the river. The great increase in sediment loads raised the riverbed below Eureka. Before the last centum, the riverbed had been aggrading at an estimated rate of one meter per years- DunnS e thirty years of tailings discharges, the riverbed rose one meter. (Church, - 000) Sediment samples from the trench were analyzed for vanadium and zinc. During the milling period, vanadium concentrations in the sediments dropped off drastically and zinc concentrations grew. The vanadium that was carried by naturally deposited sediments became diluted by the mill tailings. The tailings carried high levels of zinc. Zinc concentrations in the pre-mining sediments were an order of magnitude greater than the crustal abundance of zinc. But post mining sediments had zinc concentrations another order of magnitude higher than the pre-mining sediments documenting the overwhelming contribution to the sediment load contributed by the mills above Eureka, MEASURES OF CURRENT NATURAL AND HUMAN-RELATED LOADING SOURCES While historical information and sediment data demonstrate the effects of historical mining activities including tailings discharges into the river, it not very helpful for dividing the amount of loading caused today by natural versus human-related sources. Other studies have approached this modern day issue with varying degrees of success. Intense Water Sampling One method for distinguishing between sources is to try to monitor them alt - draining mine adits, seeps and springs. This has been attempted in several small sub-basins in the Upper Animas watershed during low flow conditions. (Wright and Nordstrom, 1999) The largest sub-basin intensively sampled was the Middle Fork of Mineral Creek, an area subject to intense geologic alteration and little mining. This area was targeted specifically because of the large natural sources of metals. One small sub-basin of the Middle Fork, informally referred to as the Red Tributary, appears to have seen little if any mining, yet the stream carries very high concentrations of metals, especially aluminum and iron. Dissolved aluminum concentrations were found greater than 50,000 jig/L. (Mast ei at., 2000) WQCC’s Table Value Standard for chronic and acute toxicity for aquatic life are 37 jig/L and 750 jig/'L respectively. Using a mass-balance approach, two efforts were made to estimate the relative contributions of natural and mining loading sources for a number of metals for the Middle Fork. The first study, conducted in 1995, found that 90% of the aluminum, 65% of the copper, 70% of the iron, 65% of the sulfate, and 35% of the zinc came from natural sources during low flow (Wright, 1997). A later study using the same 1995 data plus summer low-flow samples from 1997 and 1998 low- flow data found that 90% of the aluminum, 82% of the copper, 66% of the iron, 72% of the sulfate, and 76% of the zinc came from natural sources (Mast ei at., 2000), The differences in percentages demonstrate how a mass-balance approach works well for some metals but not all of them. Some of the metals readily sorb on to particles and drop out of solution. Small changes in water chemistry during different times of year may re-dissolve them. Metals also fall out of solution as precipitates, at varying rates and at differing pH levels. Other metals (e.g. Cd, Zn) remain dissolved at pH ranges within the Upper Basin. While studies on the Middle Fork show very high metal loading from natural sources, the results cannot be generalized. The Middle Fork watershed is less than 5% of the Upper Basin, and it has been subject to intense, highly localized alteration that is not typical of all other sub-basins. Most of the aluminum and iron in Mineral Creek is from the Middle Fork, but only a very small percentage of the copper and zinc in Mineral Creek is from this tributary. Very different results may be found in other areas. The cost of sampling all seeps, springs, and draining adits of the entire Upper Basin would be enormous and impractical. The method also doesn’t measure metal loading caused by surface runoff from both natural and human-reiated sources. In addition, it fails to take into account that mine workings in some parts of the Upper Basin may have altered the hydrology of certain areas to such a degree that natural seeps and springs have been impacted. Some work has been done using oxygen isotopes of sulfate as indicators of whether or not the sources of water are natural or mining-related (Wright and Nordstrom, 1999). Oxygen utilized in the pyrite oxidization process must come from oxygen in the atmosphere or from oxygen dissolved in water. The isotopic signatures will vary depending on the source of oxygen. It is hypothesized that oxidation occurring in mine workings will predominately use oxygen from the atmosphere, and oxidation in groundwater will predominately use dissolved oxygen m water. The study found the same percentage of sulfates came from natural sources in the Middle Fork Basin as the mass-balance approach did. The method has some of the same problems as intensive sampling. For example, it isn t use&l for determining fractions of natural versus human-related sources associated with surface runoff There are other questions about its overall application, and the technique is not widely accepted at this time. Work to refine this method of analysis is on-going. At this point, there is no definitive way to fully separate loading sources into natural and human- related. The best approach is to make the distinction between identifiable sources and unidentifiable sources. Identifiable sources are particular seeps, springs, draining adits and waste rock and tailings piles. Yet monitoring these sources may be misleading. Some apparently natural sources such as seeps may be impacted by underground workings that may have changed groundwater hydrology. Alternatively, groundwater entering a mine may already carry^high concentrations of metals so that loading from the mine drainage may not all be attributable to human activity. The loading from a mine waste pile may be measured by bracketing a site along a stream segment, but some of that load may come from via groundwater. Other groundwater sources entering the same area may contain metal loads as well. The next chapter attempts to delineate loading sources into two categories: base antj seasonal runoff. Base flow is further divided into groundwater and adit discharge. Seasonal runoff is divided into runoff from mine waste piles and undifferentiated runoff. These are roughly identifiable. No attempt is made to further sub-divide these categones into natural or human-related. Geology is one of the biggest factors controlling loading sources of metals m the Animas River Basin. The geology is what attracted miners in the first place. Mining activities can exacerbate natural processes by creating acid drainage and metal loading. The disposal of millions of tons of mill tailings directly into the river in the early 1900’s, followed by tailing pond failures later m the century, undoubtedly affected water quality in the Basin. The question of how much metal loading in Upper Animas Basin is natural and how much is human-related remains illusive. In certain locations, natural metal loading can be very substantial. The next chapter attempts to quantify metal loading coming from identifiable sources and how much may be due to unidentified sources. Black, Michael, Historical Accounts o f Water Quality in the Animas River Basin, .1878-199.1, June 1994, unpublished document. Rove D J M A Mast W G Wright, P.L. VerPlank, G.P. Meeker, and D.B. Yager, “Geologic Control ’ on’ Acidic and Metal-Rich Waters in the Southeast Red Mountain Area, near Silverton, Colorado ” U.S. Geological Survey, ICARD Conference, 2000 Survey Open-File Report 00-0244, 2000. - « r^T r- j m«ir “Prp-Mtnmc Bed Sediment Geochemical Baseline in the * - » « * » c ~ ‘ ~ 2000. F ,V D L SB Church and D M, Unnih, Geochemical and lead Isotopic Data fromSedimentCores Fluvial Tailings, Iron Fens, and ' Colorado, 1995-1999, U.S. Geological Survey Open-File Report 00-0463, 2000. Jones William R„ History of Mining & Milling Practices production in the Upper Animas River Drainage 1871 - 1991, Dec. 2000, unpublished document. Mast, M.A., P.L. VerPlank, D.B. Yager, W * . Wright a n d S° ^ °f “ *° Surface Waters in the Upper Animas River Watershed, ICARD, -000. Rodgers, Jack, Director of Public Works, City of Durango, Personnal Communication, 1999. \r k n c p riinrrh and D L Fev “G eom orphological Context of Metal-Laden Sediments in the S s L e i FiooSain; Cotoado," US. Geological SutveyToxic Substances Hydrology Program- Proceedings o f the Technical Meeting, Charleston, South Carolina, March 8-1,, 1999, Water Resources Investigations Report 99-4018A. Wright, W.G., and D.K. Nordstrom, ‘Oxygen 8-12 1999 Water Resources Investigations Report 99-40 IS A. Chapter VIII- Existing Quality and Sources of Degradation Prepared by J Robert Owen for: Animas River Stakeholders Group Table of Contents...... L ist of T a b l e s...... n List of F igu res...... hi Acronyms...... v EVALUATION OF EXISTING WATER QUALITY ...... 2 Methods for Data A nalysis...... 4 Data A nalysis...... 6 Segment 2 ...... 8 Segment 3 a ...... 11 Arrastra G ulch...... 13 Segment 3 b ...... 15 Segment 7 ...... 15 Segment 8 ...... 19 Segment 9 b ...... 20 Segment 4 a ...... 23 Segment 4 b ...... 25 Sum m ary...... 26 ASSESSM ENT OF SOURCES...... 28 Runoff Process...... 28 Metal Concentrations...... 31 Groundwater...... 37 A dits...... 39 Seasonal Runoff...... 40 Combined E ffects in the Animas River below Silverton...... 49 Other H uman Impacts; ...... 52 R eferences...... 53 A ppendices...... 55 Appendix 8 A: Contains the water quality data collected from streams and adits by the USGS, WQCD, DMG, USFS, BLM, CDOW, and the ARSG from 3991 through September 30,1999...... 55 Appendix 8 B: Contains spreadsheets used to calculate acute and chronic table value standards and the 85th percentile concentrations at selected main stem locations...... 55 Appendix 8 C; Contains an MS WORD document, WQRM.doc, that describes the regression approach for the WQRM. Also contains the data, statistics, and regression equations for dissolved and total recoverable Al, Cd, Cu, Fe, Mn, and Zn at the four gaging stations used for the W Q RM ...... 55 Table 8.2b(i) Comparison of ambient quality to TVS and adopted water qualitystandards in segment 3 a...... ^ Table 8.2b (ii) Comparison of ambient quality to TVS in Arrastra Gulch...... !.!."!"!!!!!! 13 Table 8.2c Comparison of ambient quality, 1997-99 with ambient quality, 1991-94 in segment 7 ...... ^ Table 8.2d Comparison of ambient quality, 1997-99 with ambient quality, 1991-94 in segment 8...... ^ Table 8.2e Comparison of ambient quality to TVS and adopted water quality standards in segment 9 b ...... 20 Table 8.2f Comparison of ambient quality to chronic TVS and adopted water quality standards in segment 4a...... 23 Table 8.2g Comparison of ambient quality to TVS and adopted water quality in segment 4 b ...... 25 Table 8.3 85th percentile dissolved concentrations by season for 3a, 4a, and 9b ...... 26 Table 8.4 Sources of runoff in cubic feet per second at the four gages for a base flow and peak flow m onth...... 3 j Table 8.5 Comparison of loads of individual metals from non-permitted adits in the upper Animas basin to loads at the gages during base flow...... 39 Table 8.6 Comparison of loads of individual metals from mine waste rock in the Upper Animas Basin to total seasonal runoff loads at the gages...... 42 Figure 8.1 Relationship between stream flow and solute concentration for representative solutes in the Animas River below Silverton, A 7 2 ...... 5 Figure 8.2 Principal gaging stations, A 68, CC48, M34, and A72 used for water quality analysis in the upper Animas Basin...... 7 Figure 8.3 Boundaries of Segment 2 of the upper Animas Basin and selected monitoring locations...... 9 Figure 8.4 Boundaries of Segments 3a and 3b of the upper Animas Basin and selected monitoring locations...... 10 Figure 8.5 Comparison of flow-adjusted target dissolved metals derived from the water quality regression model to chronic table value standards at A 68, the Animas River at Silverton.. 12 Figure 8.6 Boundaries of Segment 7 of the upper Animas Basin and selected monitoring locations...... 14 Figure 8.7 Comparison of flow-adjusted target dissolved metals derived from the water quality regression model at CC48, Cement Creek at Silverton...... 17 Figure 8.8 Boundaries of Segments 8 and 9b of the upper Animas Basin and selected monitoring locations...... 18 Figure 8.9 Comparison of flow-adjusted target dissolved metals derived from the water quality regression model to chronic table value standards at M34,Mineral Creek near Silverton... 21 Figure 8.10 Boundaries and selected monitoring locatins of Segments 4a, 4b, and 5a of the upper Animas B asin...... 22 Figure 8.11 Comparison of flow-adjusted target dissolved metals derived from the water quality regression model to chronic table value standards at A72, the Animas River below Silverton...... 24 Figure 8.13 Average stream flow, Animas River below Silverton showing the estimated portion that is base flow ...... 30 Figure 8.14 Comparison of total recoverable and dissolved aluminum concentrations and the cyclical variation o f pH at stream gages in the upper Animas B asin ...... 33 Figure 8.15 Comparison of total recoverable and dissolved copper concentrations and the cyclical variation o f pH at stream gages in the upper Animas B asin...... 34 Figure 8.16 Comparison of total recoverable and dissolved iron concentrations and the cyclical variation o f pH at stream gages in the upper Animas B asin ...... 35 Figure 8.17 Comparison of total recoverable and dissolved zinc concentrations and the cyclical variation of pH at stream gages in the upper Animas Basin ...... 36 Figure 8.18a Seasonal, flow-based sources of total recoverable A1 and Fe to A68, the Animas River at Silverton, estimated from the water quality regression model...... 43 Figure 8.18.b Seasonal, flow-based sources of total recoverable cadmium, copper, manganese and zinc to A68, the Animas River at Silverton, estimated from the water quality regression model...... 44 Figure 8.19a Seasonal, flow-based sources of total recoverable aluminum and iron to CC48, Cement Creek at Silverton, estimated from the water quality regression model...... 45 Figure 8.19b Seasonal, flow-based sources of total recoverable cadmium, copper, manganese, and zinc to CC48, Cement Creek at Silverton, estimated from the water quality regression model...... 46 Figure 8.20a Seasonal, flow-based sources of total recoverable aluminum and iron to Mineral Creek near Silverton, estimated from the water quality regression model...... 47 Figure 8.20b Seasonal, flow-based sources of total recoverable cadmium, copper, manganese, and zinc to Mineral Creek near Silverton, estimated from the water quality regression model ...... 4g Figure 8.21a Seasonal, flow-based sources of total recoverable aluminum and iron to the Animas ^ River below Silverton, estimated from the water quality regression model...... 50 Figure 8,21b Seasonal, flow-based sources of total recoverable cadmium, copper, manganese and zinc to the Animas River below Silverton, estimated from the water quality regression model...... C1 Acronyms Trace metals Ag Silver A1 Aluminum As Arsenic Cd Cadmium Cu Copper Cr Chromium Hg Mercury Ni Nickel Pb Lead Fe Iron Mn Manganese Sb Antimony Th Thallium Vn Vanadium Zn Zinc Major Cations Ca Calcium K Potassium Mg Magnesium Na Sodium SiO Silica Major anions C 03 Carbonate H C 03 Bicarbonate NH3 Ammonia S 04 Sulfate DO Dissolved oxygen pH Measure of acidity/basicity Units of measure cfs Cubic feet per second (28.32 1/s) 1/s Liters per second mg/1 Milligrams per liter (ppm) X)g/1 Micrograms per liter (ppb) BDL Below limit of detection TVS Table value standard WQS Water qualtiy standard ARSG Animas River Stakeholder Group CDPHE Colorado Department Public Health and Environment EPA U S Environmental Protection Agency DMG Colorado Division of Minerals and Geology BLM U S Bureau of Land Management SGC Sunnyside Gold Corporation USFS U S Forest Service USGS U S Geological Survey WQCC Colorado Water Quality Control Commission WQCD Colorado Water Quality Control Division Other AT American Tunnel UAA Use Attainability Analysis WQRM Water quality regression method CHAPTER VIH - EXISTING WATER QUALITY AND SOURCES OF DEGRADATION The hearing in 1994 changed many water quality standards for the Animas River basin. The changes, based on data collected between 1989 and 1994, reassessed the status of aquatic life and estimated the potential for establishing aquatic life in the Animas River and several of its tributaries. Since 1994, several activities affecting water quality have occurred and a substantial amount of new data has been collected. New data is used to • quantify seasonal and annual variations in loading from identifiable mining related sources, # improve estimates of metal contributions from all other sources, • evaluate seasonal variations in water quality at the four gaging stations, and * evaluate the effect recent remediation projects have had on the chemistry of Mineral Creek, Cement Creek, and the Animas River. Water quality goals that may reasonably be achieved through restoration of disturbed sites is evaluated at the end of this chapter and in Chapter XI using the new data together with the data from earlier studies. Alternative uses and standards that might be achieved through remediation are proposed in Chapter XII. The UAA focuses on stream segments with aquatic life classifications and standards disapproved by EPA in their letter of September 1998 and/or are contained in the state’s 1998 303(d) list. These stream segments are shown in Table 8.1 Table 8.1 Stream Segments Shown on CDPHE 1998 303(d) list Segment Description Use Impaired Constituents) 2 Animas above Eureka Downstream aquatic Al, Cd, Cu, Fe, Pb life 3a Animas Eureka to Cement Ck Aquatic life Zn* 3b Animas, Cement Ck to Mineral Ck Downstream aquatic Al, Cd, Cu, Fe, Pb life 4a Animas, Mineral Ck to Elk Ck Aquatic life pH, Cu, Fe, Zn* 4b Animas, Elk Creek to Junction Ck Aquatic life Zn 7 Cement Creek Downstream aquatic Al, Cd, Cu, Fe, Pb life 8 Mineral Creek above So. Mineral Downstream aquatic Al, Cd, Cu, Fe, Pb life 9b Mineral, So. Mineral to Animas Aquatic life pH, Cu*, Fe*, Zn * Standards disapproved by EPA on August 27, 1998. Vlll-l Chemical and physical water analyses were done at several hundred sites within the basin. Measures were obtained for ten different physical properties (discharge, pH, hardness, etc); five major cations; seven major anions; four nutrient species and twenty-eight different metals since comprehensive studies began in 1991. Total recoverable and dissolved (.45 micron filter) fractions were analyzed for most metals. All data are contained in Appendix 8 A. The purpose of this section is to evaluate and compare current (1997-1999) stream water quality with table value standards (TVS) used by the Colorado WQCC for adopted or proposed uses. The principal emphasis is on the aquatic life classification, however, waters classified for water supply or agriculture are discussed where appropriate. Constituents exceeding mandatory drinking water limits (MDL’s) are discussed as potential human health concerns. This section emphasizes selected sites on main stems and tributaries where data are available to characterize temporal variations in water quality. Data collected from October 1, 1996 through 1999 are compared to earlier data. This period was chosen to insure that the most recent data was used and follows implementation of the Sunnyside Gold Corporation (SGC) consent decree. The latter is important because several remediation projects have improved water quality in some segments since the standards were revised in 1995. Colorado’s “Basic Standards and Methodologies” (5CCR 1002-31) applies aquatic life standards for fifteen different metals, pH, dissolved oxygen (DO), residual chlorine, unionized ammonia (NH3), cyanide, and sulfide. DO, residual chlorine, and NH3 are associated with domestic or wastewater> which has a negligible effect on waters in the Upper Animas Basin. DO and NH3 are well within established criteria for all current use classifications and are only briefly mentioned in the UAA. Residual chlorine is usually not measured in streams and rivers. Data tor DO and NH3 are available for the Animas River below Silverton, at A72 prior to 1994 and a few sites above A72. Cyanide, associated with some mining activities, was sampled as a part of the UAA One cyanide sample exceeded the limit of detection. Hydrogen sulfide, usually associated with decaying organic matter, was not sampled for the UAA. Standards for aquatic life are established for Als As, Cd, Cr, Cu, Fe, Pb, Mn, Hg, Ni, Se, Ag, Th and Zn. These metals are evaluated depending on the type of past and present wastes that could r SCxr StrCamS m the area °r the ^ of re8ional geology. All studies have shown that Cr, Ni, and Se are extremely rare in the basin. The occurrence of Ag, As, and He are (W QCcT 1994) 6 fOUnd thCy arC USUaUy 0nly h thC immediate vicinity o f mine openings Water quality standards are also adopted for water supply and agricultural if the uses are present or have the potential to be used. Additional inorganic and metal parameters that were evaluated ^ 02+ N m ? lnf b0r0n (B)’ chIoride (Cl)’ sulfate The most common constituents exceeding agricultural criteria are Cu and Mn. Cu and Mn criteria, both 200 ug/1, apply to sensitive irrigated crops. The Animas or its tributaries are not used for irrigation until the river exits the canyon about 27 miles downstream from Silverton (segments 4b, 5a, and 5b). Localized areas near several draining adits, springs or seeps, have levels of As, Cd, Pb, or Zn that could be harmful to animals watered from those sources. Appendix 8A includes analyses for major cations (Ca, K, Mg, SiO, Na) and anions (C03 and HC03). Trace metal analyses for Sb, Vn, and Th were later requested by the EPA. These metals were rarely detected (Farrell, 1997). Waters in the basin were also screened for standard organic and pesticide residues. Trichlorethene, toluene, 2-hexanone, 1,1,2,2,-tetrachloroethane, and dieldrin were detected at low concentrations at one or more locations in the main stem of the Animas or its tributaries. None of the detected values exceeded aquatic life or human health criteria (Farrell, 1997). AI, Cd, Cu, Pb, Fe, Mn, and Zn are the metals that most affect water quality in the basin, and are the focus of the UAA. Their concentrations are high, both as total recoverable and dissolved, in different parts of the basin. Procedures for evaluating water quality and establishing standards are determined by the Colorado WQCC ("The Basic Standards and Methodologies for Surface Water" 5CCR 1002-31). Existing or ambient water quality1 is compared to TVS. The regulation defines ambient quality as percentiles of representative data. The 85th percentile is used for the dissolved metals; the 50th percentile is used for total recoverable Fe, and the 15th and 85th percentiles are used for pH. Only the lower or 15th percentile is used for pH in the UAA because of the acid conditions that occur in the basin. If ambient quality is better than TVS for the classified use, TVS are adopted. Numeric standards for aquatic life are usually based on chronic table value standards (TVS) and are considered protective of sensitive aquatic species. Aquatic life TVS for Cd, Cu, Pb, Mn, and Zn vary with water hardness. Higher metal concentrations are tolerated at higher hardness values. The practice of the WQCD is to compare 85th percentile concentrations to TVS calculated from median hardness for the segment (Susan McIntyre, personal communication). 1 Ambient quality for most metals is determined from the dissolved fraction, which is the portion that passes through a 0.45 micron filter. Standards for Fe use the unfiltered fraction for aquatic life and the filtered fraction for water supply. If natural or irreversible human-induced constituent concentrations are higher than the specified chronic TVS, but the classified use is present, ambient standards, 85 percentile (50th percentile for tree Fe) may be adopted. The EPA rejected the WQCC’s ambient standards for Zn for segments 3a, 4a, and 9b because there was no proof that high concentrations exceeding TVS lor aquatic life were irreversible. EPA rejected ambient standards for Cu and Fe in 9b for the same reason. The WQCC regulations also provide for site-specific water quality standards. This methodology may be based on either acute or chronic criteria, and may be used for aquatic life segments if factors other than water quality substantially limit the diversity and abundance of species present. Site-specific standards require a use attainability assessment (UAA) to support them. ^ The WQCC used the site-specific approach for Zn in segment 4a, however, that standard was rejected by EPA because of the uncertainty of the method used to develop it. Narrative standards (5CCR 1002-31.7 (1)) may be applied if numeric standards are inappropriate. This provision was used for segments 2, 3b, 7, and 8 owing to high natural levels of acid and metals that prevent attainment of aquatic life uses. Reduction of human-related sources from these segments, however, is critical to the achievement of goals in downstream segments. The WQCC adopted and the EPA approved narrative standards for segments 2, 3b, 7, and 8. Methods for Data Analysis Two methods were used to evaluate water quality. The first method is consistent with CDPHE practice. It compares the 85th (50th for tree Fe) percentile concentration to chronic TVS, utilizing median hardness for those constituents whose TVS are a function of hardness. The data and the calculations are in Appendix 8B. The second method uses a water quality regression model (WQRM) to account for variations in solute concentration owing to ilucculations in stream flow and season. Figure 8.1 illustrates the relationship between stream flow and hardness, Al, Cu, and Zn for A72, the Animas River below Silverton. Stream flow alone accounts for most of the variation in hardness and Al at this site. Most of the scatter in the Cu and Zn data can be attributed to stream flow and the time of the year the data was collected. These two factors account for most of the variation in solute concentration in surface water in the Upper Animas Basin. The WQRM was used to estimate hardness and selected metal concentrations as a function of stream flow and time of the year. It was applied to main stem and tributary segments in the Upper Animas Basin that had sufficient temporal data. The WQRM was not used for solutes if more than 10 percent of the values were less than detection. The methodology is more fully described in Appendix 8C. vm-4 HARDNESS Total Recoverable Aluminum 400 4000 - * * ♦ ♦ 5 > 9 e • •c • * ' 2000- r * . A •A. | 1SOO- * < I 100 v... • * **\ •• & •* ♦*“tf> » .^ ♦*» * • ,♦ • 4 .. %>, ^ __ { S00 IM» »500 2000 2500 o 500 1000 1500 2000 25 X) Stream flaw in cfs Stream flow in cfs Total Recoverable Copper Total Recoverable Zinc 70 • 1000 • 900 • « « à A » • » J ^ f 600 * ♦ | 500 V 4 ' f t * * '.* » » • | -400 • ,* ■» ------u » » « « j r ° • * 1C0 c 200 400 600 BOO 1000 1200 1400 1600 1&00 0 200 400 600 800 *000 5200 1400 1S00 15 Stream flow in cfs Stream flow In cfs Figure 8.1 Relationship between stream flow and solute concentration for representative solutes in the Animus River below Silverton, A / / This WQRM method has two advantages. It provides a means for evaluating the effect of remediation on changing water quality, and it allows for identification of streamflow and time periods when concentrations are likely to critically affect aquatic life. Different implementation strategies may be needed depending on whether critical concentrations occur at high or low flow. Solute concentrations during the base flow period, usually November through March are dominated by groundwater and adit related sources of solutes. Seasonal runoff from snowmelt and raintall, and percolation of water through the soil mantle and mining waste piles affects the solute concentration during the rest of the year. High acid potential waste rock and the regional surface geology have the greatest effect on solute concentration in the Animas Basin during the runoff period. Data Analysis The regression methodology requires that concentration data be gathered over a wide range of flow conditions and throughout the year. Year-round monitoring at four gaging stations Figure 8.2, began on October 1, 1993. These stations are generally sampled for water chemistry’at least once a month. Several other stations on the Animas River, Cement Creek, and Mineral Creek were monitored monthly for chemistry and flow by the USGS during 1998 and 1999 to characterize intermediate points for selected reaches. The intermediate stations also establish baseline quality conditions that may be used to evaluate the effect of future remediation. Summary statistics, R , standard error, coefficient of variation, and numbers of observations are in Annendix ot^. tn^Qoo8'*2 T ic 0“ ?“ '6 ^ f 5"1 Percentile concentration found in the UAA segments from 1997 1995 Seprnerrt« F T V l U *“ ^ ^ (WQS) ad°Pted ^ *e WQCC in 1995 Segments 2, 7, and 8 have narrative standards and no aquatic life classifications. Ambient to 19^4 iod ^ Pr r t0 1997 ^ COmpared t0 water quality for the 1997 to 1999 period and no TVS are given for these segments. Constituents that are present but th e ^ e 0^ 6” vatl°T f d T at'C life’human health’ or agricultural criteria less than 15% of WQS acknowledged m the text. It is presumed that these constituents meet all applicable Hardness, as a function of stream flow, is used to compute TVS for Cd, Cu, Pb, Mn and Zn m o n tir t10“ mflconcent£atl°n ofthe target meta*s and hardness was standardized to tlw average monthly steam flow at the four gaging stations. Expected solute concentrations are compared to uiJng^he WQRm ! “ ^ The reSUltS’ sh0Wn R eally, were calculated ™ n ts f AThe'TO Fe’ M)"’ T* Z,nI°r ** 1997 t0 1999 period exceed ** WQS ™ several reccT dL i t^QrLTnf V w Pn’-".S ^ Higher ‘“ «lions found in the recent data are the result of more intensive monitoring during the winter base flow The more basin n n T -Pr0V, h6S “ T™ r?fl.ection of the °P«ation of the hydro-chemical system in the basm and is not due to degradation of water quality. Aluminum, which has proven to be an important water quality factor in the winter, was sampled only in the summer before 1995. t i; c > {'i~ ' .. \ ■ ";.*. v'A;■ r>.‘v ;\ «•>..?«s».*_• v. *s« \ V1'V->A ~-v>. ♦ ..**fc-c.v < >* / ; • * •* . , ’ > ’ n s s s f c s n j ( ' u , > o x ~ \ { -•! • 7- *> ^ ‘j'j / ff«M W ill(lf i, / y f,w -1 'A' T W 604c* i C ii ->0 I \ . . V t f t V ^ 1'' v'mvViTivf1' ^^iii ' b 1' iT ”‘“ , JSK K Ai* .> v ; ' '■■ I ' J , I,' - ’' ' ”“'*•' 1 -Kwiirti/...... / M , |,‘ -'" / ' ' V ) A1 /V ) ’IT'.'I ^ l^ si4l| /»’;‘V\W ■ a.iw*M»< ’ I r \ ■, < '- t / ' { ' , . ' ¡""rv-.-'if li4V ;V ,''‘ o->wy* > / \, ft I ! f ‘ «7 ** I 7< > v 'M ‘ ’¡ f A l m • A* ’ • i « ' i.p/.ii ' h ^ \ u ' - • ' - > ■ l, n '»i ■, ;i /I ' /-r'K 'iV lV \ i'V ■ ' v\. \; '> •« 1 I'M ; - \{\ HAM, ,ri|AN \ 1 I J ^ I ) ' lN«'>1PJiAr ' ¡ J 1 \ 1 ‘ l -‘ “ \» C / ¿K <*" , r ’ f '-.’♦•'«W» PMf*. '<<** ), > r / - ' 1 ' « j i ; c \ - . I . •., " s ' I . ,,A-\„b ^ ^ - | . M . • ' I' 'M J s > i / •"'\,.-,r r .Voi«» I i is ' r-f/i I \ ^ k\hvc. iA> \M V-'v \. ]\{ I; \ * ’ k ' V ' " V - * ' i i C t \ < 1 K \ y \ I i ■ r— i I /I :r - .-vj Scynmt 4a [- - \ , k \ V ’- ■*'*— s1 \ Figure 8.2 Principal gaging stations, A68, CC48, M34, and A72 used for water quality analysis in the upper Animas Basin Segment 2 is the headwaters of the Animas River and extends to Maggie Gulch abouttwo miles south of the Eureka town site Figure 8.3. Principal tributaries include California, Placer, Picayne, Burrows, Grouse, Bums, and Eureka Gulches. Over forty mine sites withwaste rock or active drainage were sampled within the segment. Elevated levels of As, Ag Cd Cu Pb and Zn are found in California, Burrows and Eureka Gulches near the Lucky Jack, Mountain Qu , Columbus, Silver Wing, Comet, London, and Vermillion mines. Ore mills at Eureka introduced huge quantities of tailings (crushed ore) into the Animas River and onto its floodplain, principally between 1900 and 1930. This caused the channel to aggrade, which raised the base of the streambed by about one meter, since m ining began (Vincent, 1999) The result of the aggradation was to obliterate the pre-mining morphology of the stream and destroy the willows that provided bank stability and riparian habitat (Vincent, 999). Approximately 80% of these tailings have been swept downstream out of the Eureka-to- Howardsville reach (USGS, 2000), and incorporated into stream sediments. These tailings may be impacting water quality. Most water quality data has been collected from A33, the Animas River above Eureka Gulch, located near the lower end of the segment. The USGS sampled A3 3 on 12 different dates in 1998-1999 Water quality generally remains unchanged since 1994, although some remediation has occurred in the headwaters of Segment 2. The 85th percentiles show differences in Cu and Zn between the older and more recent data, however, the data is insufficient to determine if this represents a true change in water quality. Cd, Cu, and Zn remain above chromc TVS for aquatic life. The water aualitv data shown in Table 8.2a does not support the conclusion in the 303M list that the segment is impaired for Fe or P L Table 8.2a Ambient water quality, 1991-94 and 1997-99 in segment 2. Units are in micrograms per liter except pH (s.u.) and hardness (mg/1) Hard PH Al Cd Cu Fe Fe Pb Mn Zn Site Tree Dis TVS Not applicable ‘91_‘94 48 6.9 100 2.9 16 61 Bdl Bdl 800 700 A3 3 ‘97-(99 64 6.5 87 2.9 30 64 Bdl .....Bdl___ 7 8 0 ___ 5 5 0 _ Bdl=Below detection limits. Aquatic life: Water quality data at A33 indicates the segment does not meet aquatic criteria for Al, Cd, Cu or Zn, No dissolved Ag, As, or Se were detected at A33. Occurrences of Cr, Ni, and Th were rare and well below aquatic life thresholds. Human health: Drainage in the vicinity of the Lucky Jack, Columbus, and Vermillion mines and Burrows gulch exceed water supply MDL’s for As, Cd, Pb, and Zn. Agriculture: All agricultural criteria are met at A33, except Mn. Drainage near the Lucky Jack, Columbus, and Vermillion mines and Burrows gulch do not meet agricultural criteria for As, Cd, Pb, or Zn. f h ^ ^ r " > < - O -r:-'A -.U -'.\\f 1 /' }V'A, :.'v' \ 1 ' f*, . *•*?►''*.. . t' '! W"-l» ‘ V ’’ ■*'- > O-'. '•■ *- *■' >>*■■* f ^'c ’i’1’ { ' y _Vyyy^y>,'(r',y V y |-| ! £ * I ^ 1d“** "' ’’J , 'A’ 7 X.'O'i ^ • ! / > ' ,' -'V/V' " r" '' ' 1 '■ ' 'i-. . ,. ’<'-r-'•;;.<-/>'■ ■ ■'f'iXv'i/^Urv:3Vr>} -y ^ -^ ;‘ ;j*.,■vfy' - *’ • ;j V‘ 7 '' ’ ***''' ‘ •" • ’ ‘**1 *''^^J*rt- !, | \ V'*» '1: \ t V '• ^ ' \v/\V;'•../^''• y *.'• ‘ ’ ■ \ r-,^" [\ f n^;/ ; :;- .v :'/jr. ■' f I ■' ^ ■,\V \ * \ \ .■'' / y 'jl / /iV ’.-'V '., ’'''rS '| ' •-■•.’'O if W- ■ ..''•<•' vi'i ■■■ - -C , ! ■ :■ i !'/'■ • ''■ ' s '- '* " , ■■'■-'■• ” ■-. - ’ ' ' ••.;■• —■■ S. . ^ P ■ ^-:i 'einoiiian'^ ¡y X ’"r' 'Ot;P. ^ > " 3 >?"r^ ' k y %vi j;V/. r '\ ; i \ \,: i/I.'.' . ■ 1 1 ■■ ■ v '-l 1 i ; ■ • ~*! •'" '. • i'. I*1*';’- M in ify !X))- : ! v j t r ’,) ' iv ^ *' ^ |f':i // j J j i •.’- 1* ‘ ' ;l 1 ?* * / 1 r'' •-*/ 'z ■ y \l yv.\ '' ■['i' -j •'* •' 'TI'- 111 '/<■'' ^ 'i'1' ; ' V *. •;»v7(i^:-'"'':7''7^7y ;■. * lr^ .; •;i'':P7s'',:y7 ■ -i '-. / \ .V.;1' (’:■ -. V, ■^;•#*«is t^*;. ‘ iVVf* .: '■/ ,Vir7" ''' \ > ■ ' y f ■ ; '' ;'7 v'/'VV') .¡7i 1 '■ '■ 7-/777;-77 :;77 ' ; .■ / .' :'iii7iV,.y,i’7; '7:/,'‘"'.,'r.f''v77 ■'.' ■.‘"' ■-. > A1 .. i^ "Swr*M ■- - ' /'■ l. ^ j_ .■ :j' I ' ■ '' -• !i lv. \’7' ,.••■;■' '-. ''^V/ llj1 /¡.j'f •'/•' " 7 '*'"7-' '/' ',•/■ - v ...-\ ^ ^ -’'ji'/¿y 4 .-¡; 1. 1 ^ -pffi t^ i . *. V O -v , ) I y M« i ■ , ih « m ■) ; ^ ;. \ irai.ns . ■) #1« ( ' Mtfi ' - - 1 ' ‘i * ’V S , ; f! “t'r .U1' : Vi J ;•••■ it-f<**« . . . 1 / ... ij t J I >' / y ' / ; y ^ j 1 j * vr ^ x i 1 ^ \ ( ** / / r ^ *, M .*♦ , ( ? - w > ' /‘vtf f/iy v - wl . " ' U t 1 ''V / y «**/») S > > ' H Al > 1 , i / i/1/. ^ ^ , K ii c, .1 v* > ( y , i*&j>ly - / ;• , :u ^ 4 • ^ 1 v ;c u . ■ l-, ... . ■ . •___ _ , . , - . / ' A . .• 'i {///> - ’ {Segnait 3a] ■,.%... .. v . ■ * j f It* ^ •* 1 ♦ ”k l )jr J y / , u ]- 7 ' ^ “ v*: ^ ^ - ?’* 1 - /■ 1 \!‘V', t ^ Pinilid ItnmTOrOI BICfg W Mlbortl Pffiiyhfifjw w .lapopninl Figure 8.3 Boundaries of Segment 2 of the upper Animas Basin and selected monitoring loactions T-J K « . \ ( r> / ^ v *• W V < ' 1 r - " h r u : / • . t ,/.c \ / / - ■ " • iI ■■ M• i •■ ■ $ \ ■/' "" T, ' ^ • o e .r / ,t v-'i . ✓ i / ' i w.':^V. 1 1 , \VeV } s5 **» h 1 1 § A ' & 5 i - , | i ft / " ‘Jo 4,',“ ' , , , *7 (E^hlrn H/l $ ^ —**'*■ *\ ^ ^ I. W*. tl 'i i ( ’j »V, - /fflv'W 'sT V /c'S' "’"I \ , i n l ' V ' 1'1 1''»,t' r '" ¡■‘''■ ¿'/¡f 1 I N - r>* /A* >, ' Ui^ ’ ’! 1< t'V,-- % v / < / ^ g , J w /•', 1 . i1.,1' ,X •'v , ' “n /)- 1 i^A / v,>-/ • fc7 "to/vtV* 1 : ;■,%<’ -J v V t! v, }< ■A. 'S . f r f “ 'A*' \\ r ’j '1 > -' v “■ i’* -* ■ in j 1 A.’v« '1 * • •> < \ ■<• "• ^ 1»* < • ». 1 \ 1 \’« 1 *• '' - vil' 11 ■ !/ ^ > j I <* ’ ! " . V \ ( M lA»» 1 •«* f } 1 \ n * « v i << -» 11 ■%, r \ / Or«n Nuutf .•'■'J " r‘ - Y K M ( s. \ ttvW^ S i g f f J a y °f SeB"” “j* jk <■'»' " p p « B - . - 1 « t a M This segment is the main stem of the Animas from Maggie Gulch to Cement Creek at Silverton, Figure 8.4. Investigations during the early 1990’s and in 1998 showed that the segment supports several age classes of brook trout. Several large mines with drainages are present but are characterized by relatively low concentrations of metals and acidity. However, several mill sites and reclaimed mill tailings are located on terraces of the valley floor along the reach. Some mill tailings remain from circa 1930. SGC relocated some mill tailings from floodplain of the Animas at Eureka and Howardsville to the Mayflower tailings site in 1997. Monthly water quality data in segment 3a were collected by the USGS, and others, at Howardsville downstream from Cunningham Creek (A53), below Arrastra Gulch (A60), and in Silverton above Cement Creek (A68). The data at A53 and A60 show that Cd, Cu, Mn, and Zn concentrations are lower than in segment 2 owing to dilution from streams with low metal content. A53 was sampled on 15 different dates and A60 on 8 different dates during 1998-1999. The dissolved Zn at these two locations is among the lowest in the basin. The higher A1 at A60 shown in Table 8.2b reflects the concentration during the winter low flow. No winter data was obtained at either A53 or A60 before 1998. A large increase in the concentration of Cd, Cu, Mn, and Zn occurs in segment 3a between Arrastra Gulch and Silverton (A68). Stream pH in segment 3a is consistently above 6.0 and is the highest of the contested segments (3a, 4a, and 9b). This pH contributes to the low concentrations of dissolved Al, Cu, Pb, and Fe, but is not sufficiently high to affect dissolved Cd, Mn, or Zn concentrations. Aquatic life: Figure 8.5 compares the concentrations of dissolved Cd, Cu, Mn, and Zn to chronic TVS at A68 using the WQRM. Comparison of the 85th percentile concentrations of Cd, Mn, and Zn, to concentrations calculated by the WQRM shows that the 85th percentile method reflects water quality conditions that exist during the base flow and early runoff periods. The ambient concentration of Cd, Mn, and Zn, compared to chronic TVS using flow based hardness shows that these metals exceed TVS for a sustained three to four month period in the winter. Zn exceeds TVS year round, and exceeds the ambient standard previously adopted by the WQCC during most of the winter period. Table 8.2b(i.) Comparison of ambient quality to TVS and adopted water quality Site Hard pH Al Cd Cu Fe Fe Pb Mn Zn tree Dis TVS 6.5 87 1.1 10 1000 — 2.9 1700 130 WQS 6.5 87 1.7 11 194 132 3 1000 540 A53 ‘97-‘99 7.0 83 2.1 4 86 54 Bdl 262 304 A60 ‘97-‘99 6.6 150 2.4 5 — Bdl Bdl 214 277 A68 ‘97-‘99 115 6.2 115 3.0 9 227 120 Bdl 2500 900 Bdl=Below detection limits. D issolved Cadmium Dissolved Copper Manti) -Cu—— — Ao, TVS I Dissolved Manganese Dissolved Zinc Moni« Month I— -Oi, T V s '." ■ 2 o «—— — ■*£, TVS I Figure 8.5 Comparison of flow-adjusted target dissolved metals derived from the water quality regression model to chronic table value standards at A68, the Animas River at Silverton. Stream flow is the average monthly flow at A 68,1993 to 1999. Table value standards are computed from the flow-hardness regression. Computed values are for the 15th day of each month. The 85th percentile method at A68, the most intensively sampled location (n>90) on the segment, shows levels of Al, Cd, Mn, and Zn exceed the adopted WQS. The WQRM, shown in Figure 8.5, indicates there has been no increase in concentrations of Cd, Cu, and Zn between the pre- and post-1997 period, however it does suggest a higher concentration of Mn since 1997. The WQRM was not used for dissolved Al, Fe, or Pb because too many values were less than detection. Dissolved As, Th and Se were sampled but never detected in the segment. Dissolved Ag, Cr, Hg, Ni, were detected in less than 5% of the samples, but none exceeded aquatic life criteria. Human health: Samples from the main stem analyzed for total recoverable Sb, As, Ba, Hg, Ni, Cr, and Ag never exceeded water supply MDL criteria. Samples analyzed for total recoverable Be, Cd, and Pb, exceeded water supply MDL criteria in less than 11% of the samples Agriculture: Mn is the only constituent to exceed the 200 ug/1 agricultural criterion more than 15% of the time at the three stations evaluated. Since there is no irrigation, this criterion is not relevant. Arrastra Gulch Arrastra Gulch, a tributary to segment 3a, was previously inadvertently not included in any of the segments in the upper basin. Mines in the Little Giant, Woodchuck and Silver Lake sub-basins have since been extensively investigated by DMG (Herron and others, 2000). The area around Silver Lake at the headwaters of Arrastra Gulch was mined as late as the 1950’s. Many remnants of the mining days are still present. Access to most of the mines in the basin is by foot or helicopter (Herron and others, 2000). The relatively small metal loads and difficult access results in the remediation potential of these sites as being minimal and very expensive. Trout electroshocking in 1976 and 1998 indicate trout do not live in Arrastra Gulch (Fishery Report, Chapter VI-Appendix 6A). Of the five samples taken in Arrastra Gulch, Cd, Cu, and Zn concentrations exceed TVS. Of the one sample taken during June, at maximum high flow, the hardness was very low resulting in the Cu value double that of the TVS acute toxicity value. Table 8.2b(ii.) Comparison of ambient quality to TVS in Arrastra Gulch. Units are in micrograms per liter except pH (s.u.) and hardness (mg/1). ______Site Hard pH Al Cd Cu Fe Fe Pb Mn Zn ______Tree __ dis ______„ 87" 0 79 66 1000 1.7 1500 87 Arrastra 70 7.4 Bdl 1.4 8 14 13 Bdl Bdl 200 Bdl=Below detection limits. ^ 7 T _ _ - - 7 7 "TT ” - li- ’ i ■ ( Pm* ; A ' JV -'‘' / / I ' " • »‘-1, ' /r I- > . ft * ^ . . 'i • i: : " 1. r . «,-1 1 I,*. A»i \ f..*l " -r i v . v , , ' - ‘V , t " \ i - . ■ ¿I?.; • ;, ‘'5/- 1 , *■ - ,•? _ *vi* - i ** v . . - ^ _ _ .iv & * ' - ; j ‘ ‘ - !>v’ * r , - !> V / - .'&/% ‘ 7 1 I * - I 1 I >» J * * ** fBileVfi^ritl °* -v -¿iLi. r-'’«rc SW*'». v, j ^cp^.bo.l » f . i r -i *• , ,| • v . . \ kkttte* “ * L ^ V >U I / V™V U ^ i im - -J fj ) 7 ’ ^ ^ 1 < •“HfJ ,i»+ ' •** x -i ^ I" ¿fl'-t* , r - ' t ". . - - C i |J( r *' V f ^ v ' V ' ?- ’i1 <-■■'■'' w i i“ - v " ’ / * VA "if 'r*J\. \V /*!' ‘ 1-4 ^ M ‘. K : 1 ' <( \ . * * ■' / / u ji1 ')i i,V, .U( ' ■ '? ,,s f HfH?ooUr 7>.\) \* '*<•>] <1* < i * \i | '“'V ' !;• ’ ' 7 ( ' l “* V ^ ^ M W ■ ^ 1 _ _ / ! 1 \ Vi ; 1^5=11 ')'!>■ „ >i Cl frh ,l\ ^ ^ S I ^ <1 * ' Wo'ftr / » l'K * 1 i i> f 1 ( r ...... 1-.,'y i- ■rftM . ^ (. j V ^ I 'W J * \;\ *>» '«ftmiart) " ^ r V ^ 1! K ^ ' [ -; 'A; y r-!^ ^ J 'hW^’v - 't ^ •■•• ■ 1 i ■ ■• »•<•. j! .'("V-Monwiii«'';-''-', ■ ^SxV*. ' '',:' ■'-■ <, ■',- ^ r.s s S fe / : ' ' - " '• ; v ' sS. 1 ? .ij-.A' | j.' , i y: nV - ■V^VhVv > - A 7 J I"«** ■ ' ••*“ ! .Ul'„ 'l 1 !l . I MK W W ^-S, . ', . \ x ¿i • i » i t{> " f * y ^ cl' VI li*' 'V r ' i W * 1 V\';. / ' 'S I 1 J I |l 1 ..//'Jri.'-'. 1 / // ^ 1 A l A fev'Tld ‘>:sl (:/r' I ¿X n . i n i^' s J ^ c’1 i iV, j’',) l!1/ I * / ; > / \ ')'■i J u 'T / i i' t \\ \ t 'i; ir / ( \ \ Vv, ■■-Y.SS r>'" s'.:.:.j yfr-- h ‘ V A V ’V' \ -r-‘ ;/' »1 y A ' s ■y..... / -•. -.v,^ ^ y^_2^''r^&'0 "TX,v I r ^ 'I, f S v\ ^ v t ■ ^ I' I...... •\.v-.\[S egnant7 [ \ ' \ * * V *T 'V ^ > > ' /- • *■ * ^ * v >Ui ’ 'v— frt.ttix f *~S.,.>».mr.t*»'’•.-;1..*’; .,>>• • y - ^ ' f v •-••■ y^Vv' V '^ V f/ P ^ - f i f ' \i >.■''^ i ' 1 A V 'V.’ v ir t f • I Segnvnt 9b I v *•£ O r , : -. ^ v S k f f * '> , r r \ f / r r' - \ lx I • ■ ■ ' •bssct jKorthStu 1'* ~ > , ' . T'O" ^>-//-'' ■" i U< ■ 't.x \\"- m /x/iissnrir , n '/ ‘ ,{ PramdftoMTOPQI C1W3 W ildflomi pgducHoM (gw.tcmo.com) Figure 8.6 Boundaries of Segment 7 of the upper Animas Basin and selected monitoring locations This seraient is a short reach of the Animas River between Cement Creek and Mineral Creek, Fkure H It follows the east edge of Silverton. The Silverton municipal discharge is to this 4.5) and metal rich water which mixes with high pH (6.0 to 7.3) water inthe T^imas KJ Mixing of the two streams with differing pH causes rapid formation of Al and Fe colloids, which begin to settle in the reach (Schemel and others, 1999). Segment 7 Sem ent 7 is the entire Cement Creek watershed, Figure 8.6. The American Tunnel (AT) at Gladstone, S p e e c h enter CemenTCrelk a short distance belowtheAT. ^L“ S th .« «1 - ^ ^ “ Creek Prospect Gulch, and other drainages downstream from the AT. Data was coltected rrom over 40 w a l rock pibs and 29 mine openings that had active drainage within the Cement Creek basin. E S S - “ AT plant for about eight months each year between September 1996 ^ Perino, personal communication). The watershed above the AT in c lu J to n a r tC r e ^ the dissolved Cu load at CC48. During the months SGC treated the flow of Cement Creek £n t « “ .. C«8 w., «duel. b, «b.u, 212 «ft « 20 P««=nt C. w reduced by an average of 15 ug/1 or 27% to 54% for the same period. Eighty percent of the Zn and over 60% of the Cu enter Cement Creek downstream from the AT. Cem ent^Seekbetween^ros^^^^cl^and^Uvertra^'uSG^tacer1 stodies (Kimball, 2000) identified Ohio, Minnesota, and Prospect Gulches as important metal sources. Table 8.2c. Comparison of ambient quality, 1997-99 with ambient quality, 1991-94 in segment 7. Units are in micrograms per liter except pH (s.olandhardness (mg/11-— ------— - 7Site ^ :------Hard pH Al Cd Cu Fe^ Fe^ Pb M n ¿ n ------Not applicable ‘91-‘94 44 4300 5.4 110 5480 20 1500 930 CC48 ‘97-‘99 3.8 3164 2.3 84 2585^82^ These watersheds drain the acid-sulfate system, which dominates the western half of the Cement Creek basin (see Chapter VII), and are major sources of Al, Cu, Fe, and Zn. Data from Cement Creek at Silverton, CC 48, shows reduced levels of Cd and Mn since treatment of Cement Creek above the AT began in October 1996. Except for Mn, this is reflected in 85* percentile data shown in Table 8.2c. Although the data in Table 8.2c suggests an increase in the average Mn level, the WQRM, after accounting for variation caused by stream flow and seasonality, shows that it has been reduced. No change in the levels of dissolved Al or Fe at Silverton was measurable by the WQRM after treatment of upper Cement Creek was started. Treatment of Cement Creek will end after SGC completes their obligation under the Consent Decree. The WQRM, Figure 8.7, shows that the highest concentrations of dissolved Al, Fe, Mn, and Zn occur during the base flow period. The regression equations are based on data collected after the SGC consent decree was implemented, therefore these metals enter Cement Creek downstream from the AT. In contrast to Al, Fe, Mn, and Zn dissolved Cu concentration peaks during runoff, Figure 8.7. This result suggests a different mechanism is responsible for Cu loading in Cement Creek. The pH of Cement Creek is less than 5.0 for all seasons and stream flows. This low pH assures that most metals remain in the dissolved state. Aquatic life: Levels of Al, Cd, Cu, Pb, and Zn are acutely toxic to aquatic life throughout Cement Creek. Toxic thresholds are exceeded most of the year for all of these constituents. Dissolved Ag exceeded chronic aquatic life criteria in 8% of the samples at CC48. Human health: The concentration of total recoverable Th and F exceed human health criteria in more than 15% of the samples. Concentrations of total recoverable Be, Cd, Pb, and Ni exceed human health criteria in 5% to 8% of the samples at CC48. Drainage near the Lark, Joe and John, Kansas City, and Henrietta mines in Prospect basin and the Mogul and Red and Bonita mines in the Ross basin have concentrations of total recoverable Sb, As, Be, Cu, Hg, and Zn that exceed water supply MDL criteria. Agriculture: Mn is the only constituent to significantly exceed agricultural criteria at CC48 but since there is no irrigated lands this criteria does not apply. Drainage near the mines noted in the previous paragraph have concentrations of As, Cd, Cu, Pb, and Zn that do not meet agricultural criteria. D issolved Cadmium 4.0 ' Ï” J s-o 1 25 I 2.0 1,5 1.0 0.5 0.0 J J Month - C d Pr»~] Dissolved Copper j—*-c^1 Figure 8.7 Comparison of flow-adjusted target dissolved metals derived from the water quality regression model at CC48, Cement Creek at Silverton. Stream flow is the average monthly flow atCC48 1993 to 1999. Computed values are for the 15 day of each month. Concentrations are for the period after the SGC Consent Decree was implemented. i..i, g y, .V¡r . h. t ii. ij ■— ------~ r V \ lì0' i %T@eX3"Cj J I * '/ / r f ^ C ^ .* ^ 1\ ' ~ w , * , i " .vi». í / 7 ^ ‘ 4 y \ ' 8x 1 ^ i «J? >!* ar / ~>- \ V iv ^ If 1 I Aw*,,J, V‘ ; r * * s v ' \l *tfw> » „ •*{■*> m >. ./:" / r K»*toru £•« ' j i > , / i' / \y:K\-V‘"!')' ■ 'V A¿t)n v* t ) ' * ?» * J1« A « 1y ¡V‘ iti r» ‘ A «.,. ^ ^ < I«‘Í U 1 I I f r Y 0 8 i L ■ W . 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V'/|1.,', '' , , ,'l/í 5 , ' v ' ' "| I A«*1o Suoni #''.l.'ir -Vv. r J i:t-v•>•'■/■ i>-,vqm/ ; í r - '>11^;;:^', ! 1 { <./ a |\% 0^ l , i.:i| y?1, .5 /,- ill k, )< 1 , / \ t f / r ’>1 / ♦ S i , v '' A t’.*“ J m/7 /Í >,-'//? srfA i; Vi í ÍMl- • v - ^ ' í‘/!V '‘^ - i/ ,r" ^ ' *i » \\ !4 $ * (i %r°'»4 Ii / > /-J1 ^ ■í::/ U l M m u V W ■/A I n r i. »■ V » / : j a - / / / / ¡.BriTribJ ^ ‘y / > » / ) * V/j / > ? , ■ /.. -. - ? \ f r S'*'*. ^ A' í ^ V ; ia^Srta.r is »T^ , * x^-- \ ...... \ \ «V* f í \ \J / •■ i ■ ' jSeamentOhj'; s J ^ X * ^ ;)// *n * \ ¿ V« 1 i-1 i * .• '! ;-.-"*?.‘.f¿*' " y ’ ■ ...... ( .,■.,. . , ...... , ~ i - , '. /-I H ortK ^lff'. A '// j ‘Plv. í , , ' -/y,*’ " '’ '/>r- ' f\ ' ' ^* -.iíi S i ■" 'v>" \ ^ - i' ? ? / ' J,lt ' ; ''W/t V 'te ‘ PnaU j fto>n TOPO I OIP98 W iM flow Pioductiont ( w w to v o w x ) Figure 8.8 Boundaries of Segments 8 and 9b of the upper Animas Basin and selected monitoring locations S e g m e n t 8 Se„ment 8 is the main stem of Mineral Creek, which begins on Red Mountain Pass and extends £ i £ t * “ (™ { “]™ ove £ Table 8 2d Thirty mine openings with active drainage and 20 waste rock piles were sample tiiroughout Segment™. D ictio n of Cr, Se, Th, Hg. and Ni were rare and only one value (for Ni) exceeded a water quality criterion. Most of to „=,* * .« ,..» « MO, J« * » . MiM, F o * „ famtte M M c-«~ P«. area, which drains the acid-sulfate geologic system discussed in Chapters IV and Vll. in M ineral Creek (M27). Table 8.2d. Comparison of ambient quality, 1997-99 with ambient quality, 1991-94 in segment S I Tnits are in microsrams per liter excgEt^Si^).and W ) : ------■ ! £ ------W PH Al Cd Cu Fe Fe Pb Mn Zn Tree Dis ______------m Not applicable ‘91-‘94 196 4.5 5200 3.2 190 2400 6900 23 860 920 wi-3 ‘or.‘qq 6 3 67 4.9 79 — 128 452 120/ M7.7 ‘97-‘99 206 43 55g0_U ... 112 4819__4417 * _ 783^ ,.,.7_23_ * The detection limitfor Pb at these sites was 30 ug/1, which is too high to be used. The Middle Fork of Mineral Creek, entering Mineral Creek downstream from M l3, is the Al and Fe are from water draining deposits of quartz-sericite-pynte (QSP). Kimball s (personal ^mmunication) tracer study of Mineral Creek found that colloidal Cu from the RedMountain Pass area was re-dissolved in Mineral Creek after mixing with acid water from the Middie rorL [ “ orentrations of Zn measured at M27 are due to dilution from tributary waters including the Middle Fork. Aquatic life: The water quality of the segment, as shown in Table O d is notsuitable life owine to low oH and high concentrations of dissolved Al, Cd, Cu, le , n an_a/ - n - Concentrations of Al, Cu, and Zn are acutely toxic to aquatic life in segment 8. One of three dissolved Ag samples at Ml 3 and M27 exceeded criteria for aquatic lite. Human health- Total As, Cd, and Pb exceed water supply MDL criteria in die mam stem at M13 S e the MiddleFork. Drainage from the Kohler-Longfellow complex has concentrations of Cu and Zn that exceed water supply MDL criteria. Fluoride was detected in over half of the samples, but no value exceeded the water supply MDL criterion. Agriculture: Water quality in several areas of the segment is not suitable for agriculture. All of the containments originate from the Kohler-Longfellow complex near Red Mountain Pass. Concentrations of As, Cu, and Mn exceed agricultural criteria at M l3. Cu and Mn agricultural criteria apply to irrigation, which is not a use of the segment. Cd and Zn exceed agricultural criteria near Red Mountain Pass. Segment 9b This segment is the main stem of Mineral Creek from South Mineral Creek, segment 9a, to the confluence with the Animas River, Figure 8.8. The WQCC adopted the aquatic life use and numeric standards for Al, Cd, Cu, Fe, Pb, Mn, and Zn based on remediation potential of metal loading from the Red Mountain Pass area. EPA disapproved ambient standards for Cu and Fe because they were not consistent with requirements in the federal water quality standards regulations (40 CFR 131.11). The North Star mine is the only mine site on the segment above the sampling station at M34. The majority of the metals in the segment are from upstream in Segment 8. As, Sb, Be, Cr, Ni, Se, Hg, Ag, and Th were rarely or never detected at M34, above Silverton, and never exceed aquatic life, human health or agricultural criterion Aquatic life: The 85th percentile method shows that Al exceeds both chronic and acute criteria (750 ug/1) for aquatic life at M34. The level of Al is about three times higher than the acute criterion for aquatic life for more than four months in the winter. Cu and Zn exceed acute and chronic TVS, but they are equal to or less than the temporary modifications adopted by the WQCC in 1995. Cu and Zn exceed TVS most of the year, Figure 8.9. The benefits of partial remediation at Kohler-Longfellow and Carbon Lakes are measurable in Mineral Creek, at M34. Cu and Zn levels are lower than the adopted temporary modifications. After accounting for the effects of stream flow and season, the WQRM shows an average reduction in Cu and Zn of 11 and 98 ug/1, respectively, at M34 since 1995. Cd exceeds TVS during the spring runoff. Pb exceeded the aquatic life criterion in 2% of the samples. Table 8.2e. Comparison of ambient quality to TVS and adopted water quality standards in sggment 9b. Units are in micropyams per liter except pH (s.u.) and hardness (ms/D. Site Hard pH Al Cd Cu Fe Fe Pb Mn ______.______Tree P is ______TVS 6.5 87 1.9 18 1000 TOO 6.1 2200 ’237™ WQS 6.5 87 1.7 57 5515 3415 7 1000 544 -M 3.1 *97-*99 228 4.8 2097 1.6 49 4233 3300 2 471 482 Data collected since 1995 shows the importance of Al as a contaminant in this section of Mineral Creek. Most of the dissolved Al is from the Middle Fork of Mineral Creek. The pH of Mineral Creek at M34 is less than 5.5 more than 50% of the time during base flow. Colloidal Al forms when the pH rises above 5.5 (Nordstrom and others, 1999). Most of the Al, therefore, remains dissolved in the winter, forming colloids after Mineral Creek mixes with the Animas River. In the summer, most of the aluminum is in the colloidal form. High Fe concentrations accompany the high Al values observed at M34. The Fe is from the same quartz-sericite-pyrite assemblage as the Al. Dissolved Cadmium Dissolved Aluminum 1—a __ Ol TVS------Cd ump'l | — ■— A l — « — <*, T V S------• « . T V ?] Figure 8.9 Comparison of flow-adjusted target dissolved metals derived from the water quality regression model to chronic table value standards at M34,Mineral Creek n®ar Sllve^ " ’ ^ am flow is the average monthly flow at M34, 1993 to 1999. Table value standards are computed from t h e flow-hardness regression. Values are for the 15 day of each month. Figure 8.10 Boundaries and selected monitoring locatins of Segments 4a, 4b, and 5a of the upper Animas Basin Human health: One percent of the total recoverable Pb samples exceeded water supply MDL criteria. Barium and fluoride were detected in most of the samples, but never exceeded water supply MDL criteria. Agriculture: Mn is the only constituent that does not meet agricultural criteria. The Mn criterion is a crop irrigation requirement, which is not a use of water in the segment. Segment 4a Segment 4a extends from the confluence of Mineral Creek and the Animas River to Elk Creek about 5.5 miles downstream, Figure 8.10. Water quality mvesugat.ons ot the eady W O s found minimal aquatic life in this segment. Dissolved Zn, followed by dissolved Cd and Cu, were thought to be the main cause of impairment. The effects of Al and Fe were also thought contribute to the impairment. Improvement of this reach so that it is capable of supporting aquatic life is one of the goals of the ARSG. Sb, As, Be, Cr, Ni Se, and Th were rarely detected and never exceeded an aquatic life, human health, or agricultural criterion. Aquatic life: Data for segment 4a, the Animas River below Silverton, as measured at A72, indicate levels of Al, Cd, Cu, Fe, Mn, and Zn all exceed water quality standards for using the percentile method, Table 8.2f. The highest levels of Al, Cu, Fe, Mn, and Zn are observed during base flow. The pH is commonly less than 6.0 during the base flow. Comparison of pre-1997 data with post-1997 data, using the WQRM, shows duality over the 1991 to 1999 period. Limited base flow data was available at A72 prior to 1995 because the site lies in the path of a major snow slide chute and winter sampling was inadvisable for safety reasons. Most base flow data obtained since 1995 was obtained by residents familiar with local weather and avalanche danger. The WQRM shows Cd and Cu slightly exceed chronic TVS during portions of the year, Figure 8.11. Al exceeds the chronic criterion for aquatic life for most of the base flow period, Figu 8.11. Zinc exceeds both acute and chronic TVS year round and exceeds the temporary modification adopted by the WQCC during base flow. The data indicate segment 4a functions chemically similar to segment 3b. Complex mixing reactions involving the formation of Al and Fe colloids and co-precipitation of Cu, and Zn that originate in Cement and Mineral Creeks are active during parts of the year. Table 8.2f. Comparison of ambient quality to chronic TVS and adopted water quality standards in segment 4a. Units are micrograms per liter IxcggtjH and hardness_(gg/l^ Site Hard pH Al Cd Cu Fe Fe Pb Mn Zn Tree Dis TVS------6:5....87 ll~l5 1000 300 4.7 2000 194 WOS 6.5 87 1.6 13 2000 390 5 1000 520 A72 ‘97-‘99 180 5.8 554 2.0 20 2064 2326 Bdl .....J6QQ------ZZ1 Human health: Total recoverable Cd exceeded water supply MDL criterion in 4% of the samples. Total recoverable Pb exceeded water supply MDL criterion in 2% of the samples. D is s o lv e d Z i n c M o n t h ¡ — ■♦—■chi TVS » Zn ———-Zn, tamp — »—«Ac, TVS I Figure 8.11 Comparison of flow-adjusted target dissolved metals derived from the water quality regression model to chronic table value standards at A72, the Animas River below Silverton. Stream flow is the average monthly flow at A 72,1993 to 1999. Table value standards are computed from the flow-hardness regression. Computed values are for the 15th day of each month. Agriculture: Cd exceeded agricultural criterion in 2% of the samples. Mn exceedances of agricultural standards are not relevant since there is no irrigation. Segment 4b This seament extends from Elk Creek in the Animas River canyon to Junction Creek near downtown Durango, Figure 8.10. Investigations by the ARSG (Cady and others, 1996) and the USFS did not identify additional sources of metals within the canyon reach. Concentrations of dissolved Al, Cu, Fe, and Zn are attenuated as metal free water enters the segment and as the pH rises. The Animas River exits the canyon about 27 miles below Elk Creek near Baker s Bridge. Sand and gravel mining, agriculture, and urbanization in the Animas V alley replaces hardrock m in in g as the human-related factors that impact water quality after the river leaves the canyon Water quality in segment 4b was monitored by the Colorado River Watch program at Baker Bridge (A75), Trimble Lane (A89), and Durango High School (A90). Table 8.2g. Comparison of ambient quality to TVS and adopted water standards in seament 4b. Units are in micrograms per litCTexcept pH and hardnessj mg/l).,------^ cd Cu Fe v Pb M n Zn 300 3.3 50 147 TVS 6.5 - 1.2 11 1000 1509 300 7 210 182 WQS 6.5 - 1.6 17 4 625 Bdl 326 159 A75 497-‘98 130 7.5 - 0.5 403 173 120 A89 497-‘98 150 7.1 - 0.3 5 345 143 112 A90 ‘97-‘98 196 7.6 - 0.2 4 Bdl=Below detection limit. Aquatic life: Dissolved Cd, Cu, Pb, and Zn, in segment 4b as measured in the Animas River at the upper most station, Baker’s Bridge (A75), between 1997 and 1999 are lower than the adopted standards, Table 8.2g. This improvement may be a reflection of remediation activities undertaken since October 1996 or variances in stream flow conditions that existed when the river was sampled. No discharge measurements are made at Baker’s Bridge, therefore stremn flow was estimated using concurrent upstream and downstream daily discharges. The WQRMwas used to estimate chronic TVS as a function of hardness and Zn concentration. The WQRM did not detect a change in concentration due to upstream remediation. Moreover, Figure 8.12 indicates that dissolved Zn exceeds TVS most of the year. Water supply: The segment is classified for water supply. Water supply MDL criteria are met for all sampled constituents. The ambient concentration of Mn at Baker s Bridge, A75, shown in table 8.2g exceeds 200 ug/1, however ambient Mn concentrations can be used as recommended standard. Agriculture: The ambient concentration of Mn at B a k e r ’ s Bridge, A75, showni in table 8 2g exceeds TVS for Mn for agricultural use. However, this criterion is applied only f irrigation of low pH soils. Soils in this segment are known to be moderately alkaline. W ater quality monitoring between 1997 and 1999 found concentrations of Al and Zn exceeded the standards adopted by the WQCC in 1995 using the 85th percentile methodology in segments 3a, 4a, and 9b. The 85th percentile method shows that higher levels of dissolved Al and Zn occur during the winter low flow, Table 8.3. Multiple regression analysis of the data collected at four gaging stations between 1991 and 1999 also shows that most of the exceedances are during winter base flow. Stream flow and seasonal factors were not specifically considered when the 1994 standards and goals were set. Higher concentrations of Al, Cd, Cu, and Zn per unit of discharge occur during base flow than at other times of the year. Zinc concentration elevates during winter base flow, reaching a maximum from around April 15 to the end of May when the peak runoff period begins. Al concentration exceeds chronic criteria for aquatic life in segments 3a, 4a, and 9b from December through May and exceeds acute standards in segments 4a and 9b for the same period. Cu concentration exceeds chronic TVS in segments 4a and 9b during the runoff period. Zn exceeds acute and chronic criteria in all three segments most of the year. Flow and seasonal factors that affect the concentration of priority metals will dictate remediation strategies and the ability to meet water quality goals for aquatic life. Remediation activities undertaken by SGC, ARSG, and others show measurable reductions in Cd, Cu, and Zn in Cement Creek at Silverton during parts of the year. Reductions in Cd, Cu, and Zn have also been observed in Mineral Creek. Table 8.3 85th percentile dissolved concentrations by season for 3a, 4a, and 9b. Units are in micrograms per liter except pH (s.u.)______pH Al Cd Cu Fe Pb Mn Zn 3a Apr-Oct 6.4 70 1 5 120 Bdl 1100 420 Nov-M ar 6.1 133 4.5 10 120 Bdl 3400 1179 4a Apr-Oct 6.1 80 .0 8.3 895 Bdl 1070 430 Nov-Mar 5.5 752 2.3 21 2749 1.0 1960 752 9b Apr-Oct 6.1 88 0.4 7 1760 Bdl 310 239 Nov-Mar 4.8 2568 1.8 54 3700 1.4 542 530 Bdl=Below detection limit. Zn_Dis — ch, TVS Figure 8.12 Comparison of flow-adjusted dissolved Zn derived from the water quali^ regression model to chronic table value standards at A75, the Animas River at Baker s Bndege Stream flow is the average monthly flow at A75, 1993 to 1999. Table value standards axe computed from the flow-hardness regression. Computed values are for the 15 day of each month. ASSESSMENT OF SOURCES The concentration of solutes in the waters of the Upper Animas Basin reflects natural and human-related factors. The acid environment that exists today results from geologic processes that formed the San Juan caldera and the subsequent circulation of fluids rich in sulfur and base metals, as described in Chapter VII. Oxidation of pyrite, the most widespread sulfide mineral in the basin, is the source of most of the acid water. Mining exposed additional suliur bearing minerals to oxygen in adits, stopes, and shafts leading to acid mine drainage. Weathered waste rock and mill tailings, rich in metal sulfides, removed from the mines are another source of acid and metals in the water. Minerals containing Al, Cd, Cu, Pb, Mn, and Zn that contact acid waters dissolve, and the metals are transported to the streams. The purpose of this chapter is to identify principal sources of acid water and metals that are “irreversible” or naturally occurring and those that have been aggravated by human activities, and have the potential for remediation, identified as "reversible". This section considers the sources of solutes measured at the gages on Cement Creek, Mineral Creek, and the Animas River. Runoff Process To better understand sources of metals, it is helpful to understand runoff processes. The runoff model used in this discussion is taken from Knighton (1984). Water reaching the ground surface from either rain or snow can follow several paths on its way downslope. Where the maximum rate of absorption exceeds the rate of receipt, water infiltrates the surface and either moves downward to replenish the groundwater reservoir or flows laterally as throughflow. Throughflow may be diffuse when water flows through the matrix of the soil or mine waste or concentrated in faults or fractures of variable size or location. Water moves more slowly within the soil so runoff following this path reaches the stream some time after the precipitation event(s). Moreover, throughflow has the opportunity to contact acid bearing material or soluble salts for a sustained period, thereby increasing the quantity dissolved. Mine workings expand the size and frequency of the faults and fractures. Alteration of natural flow paths creates “pipes” for throughflow and groundwater. Runoff is also generated as overland flow. This is most common in the Animas Basin during the annual snowmelt period. Overland flow occurs when the ground becomes saturated or when rainfall intensity exceeds the infiltration capacity of the soil mantle. Saturation overland flow depends on the moisture content of the soil and waste material before, during and after snowmelt or other precipitation events. If the precipitation is sufficient to saturate the deeper and less permeable soil layers, throughflow will be deflected closer to the soil surface as the level of saturation rises. If the soil becomes saturated to the surface, saturation overland flow occurs. Overland runoff also occurs if rainfall intensity exceeds the infiltration capacity of the soil mantle. This type of runoff is produced more or less instantaneously and simultaneously over a basin during a heavy rain. These events occasionally produce high flood peaks and high concentrations of suspended sediment and metals, but they are relatively infrequent and produce a small portion of the metal load on an annual basis. These events are of most concern if they cause metals concentration to approach short-term or acutely toxic thresholds. This section is primarily concerned with long-term toxic events thus metals produced from single storm events are only briefly considered. Water reaching the Animas River at A72 will have followed one of the several routes described above. Each route gives a different response to snowmelt or rainfall in terms of the volume of flow, the timing of contributions to the stream, and the concentration of solutes. Figure 8.13 shows the average annual hydrograph for the Animas River below Silverton, A ll. The total flow at A72, for convenience, is divided into two parts: base flow and “seasonal runoff’. The distinction is based on the time of arrival in the stream rather than the route followed. Groundwater flowing at depth beneath the surface moves relatively slowly, so its outflow into the stream lags behind snowmelt and rainfall and tends to be very regular. Water emanating from pipes such as a wastewater treatment plant or a mine adit is also relatively stable. These two sources comprise the base flow that sustains the rivers at A68, CC48, M34 and A l l from November through February. Seasonal runoff includes the throughflow and overland flow components of the runoff model. It usually starts slowly in March, reaching a peak in mid-June. Runoff lasts through the rest of the summer and fall, several months after the previous winter’s snow is gone. The dashed line in Figure 8,13 is the estimated base flow during the seasonal runoff period. Table 8.4 shows the sources of runoff at the four gages during February, the lowest flow month and June, the highest flow month. Groundwater, adits, and two permitted point sources comprise the streamflow during February, as seasonal runoff is nonexistent. The discharge from most adits was sampled as a part of the UAA studies. Similar data are available for permitted point sources. Therefore, subtracting known discharges from adits and point sources from the total discharge at base flow gives an estimate of the contribution from groundwater. Adit discharges and loads may be overestimated because most of the low adit flows were sampled in September or October, and it was assumed that they were flowing at the same rate in February. In addition metal loads from natural ground water sources that enter mines were not subtracted from the discharge load. It was also assumed that all of the flow emanating from the adits reach the nearest gage as surface flow and did not reenter the groundwater. During high flow measured sources—adits and point sources-were subtracted from the total flow and the remainder partitioned as seasonal runoff (throughflow) or base flow. Base flow which by definition is relatively constant, for the peak flow month was conservatively estimated to double the February amount. Seasonal runoff was estimated by subtracting measured sources and base flow from the total discharge. Stream flow in cubic feet per second vrg Sra Fo, nms eo Silverton below Animas Flow, Stream Average th n o M Table 8.4 Sources of runoff in cubic feet per second at the four gages for a base flow and peak flow month A68 CC48 M34 A72 Source February Point source 0 2 0 2.2 Adits 8.8 3.3 6.1 18.2 Ground water 19.2 8.7 15.9 39.6 Seasonal RO 0 0 0 0 Total Runoff 28 14 22 60 June Point source 0 2.3 0 2.5 Adits 8.4 7 6 23.4 Ground water 38 18 32 80 Seasonal RO 574 140 458 1161 Total Runoff 620 167 496 1267 Notes: The flows from the three upstream gages and A72 do not add up because there is an ungaged area between the four gages. Throughflow and overland flow both affect the records differently for the two months. The Silverton municipal discharge is between M34 and A72. Metal Concentrations This section identifies the sources of metals that make up the instream concentration during different parts of the flow year, that is, base flow and seasonal runoff. The analysis considers the solute load, which is the product of flow times solute concentration (a conversion factor may be included to express the result in pounds, kilograms or other convenient unit). Typically, the solute load is highest when the runoff is high, however, the concentration of metals is more important to the health of aquatic life than the load. Generally, the Animas River and its principal tributaries have the highest concentrations of metals during base flow when the loads are the least. The approach used here, therefore is to remove the effect of stream flow and focus on the percentage of the concentration of target metals from natural and human-induced sources arising during base flow and seasonal runoff. The WQRM was used to estimate the concentration of total recoverable Al, Cd, Cu, Fe, Mn, and Zn at A68, CC48, and M34. The percentage of the concentration, weighted by the proportion of load, of each metal was allocated to groundwater and adits (base flow), or seasonal runoff. For example, if 20% of the load at a gage came from adits and those sources were removed, the concentration at that gage would drop by 20%. Therefore, 20% of the concentration is attributable to the adits. During base flow, November through February, all metals were assumed to come from adits or groundwater, therefore the groundwater component was estimated as the total concentration minus the adit component. Seasonal runoff includes metals transported as both overland flow and throughflow from the soil mantle, alluvial fans, and waste rock found in the watersheds. The loads from most adits were measured during both low and high flow periods, therefore the adit contribution was seasonally adjusted. The groundwater component cannot be directly measured during runoff so it was conservatively assumed that it could double between the lowest flow month (February) and the highest flow month (June). In order to double the base flow load for this interval it was necessary to increase the base flow load by 15% per month. Between March and October the concentrations from adits and groundwater were subtracted from the total concentration and the remainder was attributed to seasonal runoff. Several of the metals change from dissolved species to colloidal or particulate species owing to inflows with different chemistry. In order to minimize the apparent loss of metals due to a change in species, the total recoverable fraction of Al, Cu, Fe, and Zn are used for this analysis. Concentrations of total recoverable Al, Cu, Fe, and Zn should be equal to or higher than dissolved concentrations used for water quality standards and biologic toxicity. The solutes, especially Al and Cu, change from dissolved to colloidal species at pH levels frequently found in the Basin. Figures 8.14 to 8.17 compare total recoverable and dissolved Al, Cu, Fe, and Zn concentrations estimated by the WQRM at the four gaging stations. The secondary vertical axis (right hand) shows the average variation in pH over the annual cycle. One of the most notable features of these four figures is that the concentration of total recoverable and dissolved Al and Cu in the low pH waters of Cement Creek are similar. These graphs also show that there is more Al (Figure 8.14) and Cu (Figure 8.15) in the Animas and Mineral Creek than is indicated by dissolved concentrations used for establishing water quality standards. Total recoverable Fe concentrations are significantly higher at CC48, M34, and A l l than the dissolved Fe concentration, Figure 8.16. This does not appear to be a function of pH within the pH range observed in the Upper Animas Basin. No graph is shown for Fe at A68 because most of the dissolved values are less than detection. A second feature is that the concentration of total recoverable and dissolved Zn at all four gage sites is similar despite wide differences in the pH patterns among the four streams, Figure 8.17. The pH of Cement Creek is consistently less than 5.0, while the pH of the Animas at Silverton (A68) fluctuates around 7.0 with very little cyclical variation. Total recoverable and dissolved Zn concentrations at M34 and A72 are nearly the same, even with the strong cyclical pH found in Mineral Creek and moderately strong cyclical pattern at A ll. T o ta l Recoverable Aluminum, Animas River at Silverton, A68 6000 \\ /- 5000 ■*x X - 4000 - 3000 \ V . // ___ \ \ / / 2000 — " / N _ - 1000 ♦ ♦ ♦ ♦ ♦ * 0 ♦ ♦ ♦ JF M A M J J A S 0 S D M o n th - Total Ree------Dissolved * 1 Mineral Creek, M34 Animas River below Silverton, A72 M o n th M o n th •Toral Rec —— Dissolved ♦ pH •Total Recov------— Dissolved ♦ pH Figure 8.14 Comparison of total recoverable and dissolved aluminum concentrations and the cyclical variation of pH at stream gages in the upper Animas Basin, Dissolved aluminum for the Animas at Silverton, A68, is not shown because most observations are less than detection. 1______Total Rae------Dissolved ♦ . T o ta l Recov------Dis Cu ♦ Animas River below Silverton, A72 Mineral Creek, M34 8 .0 60 • 7.S 8 .0 s o - _ 50 • 7 .0 7 S *>« 7 0 • » 6.S / \ * — — ?.n e 4 0 - / \ - 6 0 - ♦ ♦ ♦ ♦ / ♦ s - fi.S - 6.0 Î, 50 • = s o ------^ ♦ ■ 6 .0 is v . • 5.5 4 0 —* ------V * V / N. \ / ------*— S.S § 2 0 • 5.0 30 \ >• fi \ y S.O S 20 ♦ 10 ♦ ♦ \ ✓ — / ------4 S ------V - 4.0 10 N. 0 0 • 4 .0 M A M J A S O N 0 J F A S 0 N 0 F M A M J M o n th M o n th j______Total Recov------Dissolved ♦ pW | pH ¡ I — Total Rec------Dissolved ♦ m Figure 8.15 Comparison of total recoverable and dissolved copper concentrations and the cyclical variation of pH at stream gages the upper Animas Basin. Mineral Creek, M34 8.0 7000' 7.5 6000 ♦ / 7.0 s 5000- £ \ * * # 6.5 g 4000* 6.0 1 i 3000- • 5.5 s * \ ^ / ♦ 1 2000 5.0 2 ♦ ♦ • — / / 1000 4.0 0 JFMAMJJAS0ND Month •Total Recov------D issolved ♦ p H ) |_____ Total Recov------Dissolved ♦ pH | Figure 8 16 Comparison of total recoverable and dissolved iron concentrations and the cyclical variation of pH at steea m gages m ^ at Silverton, A68, is not shown because most observations of dissolved ,ron are less than detect™. upper A n im as River at Silverton, A68 Cement Creek CC48 Month Month •Total R e c o v ------pis ♦ pfl | •Total Recov — — — - D i s s o l v e d « < Mineral Creek, M34 Animas River below Silverton, A72 OJ Q\ • 7.5 a 9 7 .0 ^ a ♦ ♦ * i • 6.5 * ♦ \ 6 .0 s * /// 5.5 i ♦ 5.0 2 * ♦ \♦v /// ✓ 4 .5 j F M A M J J A S 0 N D Month M o nth j------— Total Recov------Dissolved + *1 •Total Recov------Dissolved ♦ pH j Figure 8.17 Comparison of total recoverable and dissolved zinc concentrations and the cyclical variation of pH at stream gages in the upper Animas Basin. The contribution of solutes from groundwater may include both natural and human-induced components. Underground mine works that intersect faults and fractures, may convert groundwater contribution to an adit source. The SGC consent decree recognized that filling the Sunnyside mine with water could cause a re-emergence of solutes from ground water as the mine workings, faults and fractures filled with water. It has also been hypothesized that underground works have changed ground water hydrology, and the potential exists for metals to emerge as groundwater rather than adit. Sources from groundwater, for the most part, were estimated as un-sampled flow. For example, a large increase in load measured between two points with no visible surface inflow was attributed to groundwater. At some locations it was possible to conclude that the un-sampled flow was natural because mining activity was minimal in the area. In other cases there was uncertainty as to the presence of sub-surface mining activity or leaching from waste material, thus no conclusion as to whether the solutes were from a natural or human-induced source could be made. The most significant observation is that contributions of solutes from the groundwater pathway are specific to each metal and to each of the three sub-basins. The contribution of groundwater to solute concentration at A68, CC48, and M34 are shown in Figures 8.18 to 8.20. Groundwater accounts for nearly all of the base flow concentration of A1 at A68, Figure 8.18. The concentrations of A1 and Fe, however are low and owing to river pH above 6.0, are insignificant as; sources of dissolved Al and Fe to down stream segments. Glacial and alluvial sediment deposits fill the Animas valley between Eureka and the canyon south of Silverton, creating a potentially large ground water reservoir. Ore mills between Eureka and Silverton supplied huge quantities of tailings that were stored on the floodplain and terraces. Vincent and others (1999) estimated that near Eureka the fine fraction of streambed and floodplain sediments deposited after 1900 is composed of two-thirds mill tailings. Tracer studies by the Paschke and others (2000) concluded that most of the Zn loading to the Animas River between Eureka and Silverton was from ground water entering the river near sites containing mill tailings. Surface sources of metals from tributaries or adits in the reach are minor. Moreover, the concentration of Cd, Cu, Mn, and Zn increases earlier in the year at A68 than at CC48 or M34. The potential volume of water stored in the valley fill makes it difficult to make a sharp distinction between the groundwater and seasonal runoff components as the valley floor is subject to throughflow and saturated overland flow. Mill tailings scattered throughout the alluvium makes it difficult to be certain of the portion which may be natural and the portion that may be human-induced. A tracer dilution study by the USGS (Paschke and others, 2000) in August 1998 found the largest increases in Cu, Mn, and Zn loads were from groundwater between Howardsville and Silverton. This study concluded that “The influence of ground water discharge was particularly evident downstream from Blair Gulch.. Paschke and others (2000) found the largest increases in loads downstream from tailings near the Mayflower Mill, below Blair Gulch, below Howardsville and below tailings near the Lackawanna Mill. Groundwater appears to be the source of most of the Al, Cu, Fe, and Zn in Cement Creek during base flow, Figure 8.19. Since SGC began treatment of all water in Cement Creek above the AT in late 1996, and it is assumed that treatment will end, concentrations shown in Figure 8.19 are for the pre-consent decree period. Treatment at the AT has lowered the Zn concentration by more than 200 ug/1 during the winter. The reduction comes from both adits and natural groundwater. Between the AT and CC48 stations, relatively low concentrations of Al, Fe, and Zn measured from adits show they are a small proportion of those metals at CC48 during base flow. This suggests that most of these metals are from groundwater, minimally affected by mining. Over half of the Cu measured at CC48 is from groundwater during base flow. Groundwater accounts for a minor percentage of Al, Cu, Fe, and Zn concentration in Cement Creek during the runoff months. Tracer-injection studies of Cement Creek by the USGS in September 1997 found that only about half of the Zn load was from identifiable tributary and mine sources (Kimball and others, 2000). The difference is attributed to loads contributed from un-sampled flow. Kimball identified two discrete reaches of Cement Creek, an iron bog below Prospect Gulch and a bog lower in Cement Creek where the increased Zn load corresponded to areas containing substantia] fracture patterns, but no mining activity. A second source of subsurface inflow measured by Kimball in Cement Creek was in areas with large alluvial fans, such as those found at the bottom of Prospect, Minnesota, and Ohio Gulches (Kimball and others, 2000). Mines and waste rock are found in all three drainages, thus the contribution of Zn may be from water affected by mining and mined sources that reaches the stream as throughflow in the large alluvial fans near their bases. Investigations of Mineral Creek (Yager and others, 2000) identified large quantities of Al and Fe in springs from areas that are not affected or only minimally affected by mining. Figure 8.20 shows that nearly all of the Al and most of the Fe in Mineral Creek at M34 is from groundwater year round. Most of the Al and Fe in Mineral Creek are from the Middle Fork of Mineral Creek. A tributary to the Middle Fork, nicknamed “Red Trib” (M18) is the largest source of Al and a major source of Fe in Mineral Creek. This area has not been impacted by mining. The Paradise Portal, a short distance upstream from the “Red Trib,” is a second source of Al and Fe to Mineral Creek. This is a shallow portal, possibly abandoned when an underground fracture or fault containing a large volume of water, was encountered. The metals from this source quite possibly were naturally present since the collapsed portal excludes oxygen, a necessary element for AMD. Springs emanating from other shallow prospects, such as the Ferrocrete and Imogene mines, in the Mineral Creek watershed, are large sources of Al and Fe and are similar to the Paradise adit. In contrast to the large percentage of Al and Fe that are from groundwater, Figure 8.20, a relatively small proportion of the Cu and Zn in Mineral Creek are attributed to groundwater. Shallow wells, driven into in the gravel in and around Silverton provide an overview of the Animas, Cement and Mineral Creek ground water flow regimes. Water from these wells showed varying concentrations of Cd, Cu, Pb, Mn, and Zn. The highest concentrations of Mn and Zn, 66,000 and 7000 ug/1 respectively, were found at the Silverton campground near the north end of town. The well at the Silverton campground is upstream from A68, and groundwater from this area probably has an effect on the level of metals in surface water measured at A68 and A72. One well near the wastewater treatment plant at the south end of town, had 385 ug/1 average Zn concentration. Table 8.5 Comparison of loads of individual metals from non-permitted adits in the upper Animas basin to loads at the gages during base flow. ______Low flow load measured from adits in pounds per day__ Adit flow Al Cd Cu Fe Mn Zn (cfs) Animas A68 5.3 9 0.10 1 42 44 24 Cement CC48 3.2 12 0.07 1 135 39 14 Mineral M34 6.1 141 0.32 29 750 65 94 Gage Flow(cfs) Average total load at the gages during February. Animas A68 28 31 0.30 4 49 334 136 Cement CC48 14 451 0.10 3 1025 135 67 Mineral M34 22 521 0.10 7 679 64 64 % of Flow Percent of the total base flow load from adits Animas A68 19% 30% 32% 20% 86% 13% 18% Cement CC48 23% 3% 70% 36% 13% 29% 21% Mineral M34 28% 27% 318% 413% 110% 101% 146% A dits Water quality investigations by the ARSG, CDPHE, USGS, USFS, BLM, SGC, and other private interests, sampled drainage from 173 adits and prospects within the Upper Animas Basin for the target metals. Other mine openings were inspected at different times, but they were not discharging. Most mines were sampled at both high and low flow periods. A few mines with winter access were sampled year-a-round. Sampling revealed that the discharge from most adits is relatively constant throughout the year. High flow is seldom twice that of low flow. The proportion of metals from adits to the down stream concentration is largest during base flow. Discharge from adits has very little affect on the concentration of most metals observed at the three gages during the runoff months of May through October, Figures 8.18 to 8.20. The average load from adits of each of the six metals in the Animas River above Silverton, Cement Creek and Mineral Creek are shown in Table 8.5. February is used because it is the lowest flow month when seasonal runoff is most likely to be zero. The loads in Table 8.5 probably over estimate the loads from adits in February because most low flow samples were from September or October and it’s assumed the load remained constant into the winter. Table 8.5 also assumes that all metals from adits reaches the gage without any attenuation. The numbers for Cd, Cu, Fe, and Zn loads (and possibly Mn) from adits in Mineral Creek, suggest that either the loads from adits aren’t constant, or there is attenuation. Several adits in the Upper Animas Basin have already been sealed or the discharge is being treated. The AT, located on Cement Creek near Gladstone, historically was a large source of metals. Drainage from the AT has been treated at varying levels since the 1960’s. Removal of the largest quantities of metals began 1989. A bulkhead, placed in the tunnel in late 1996, partially sealed the discharge. Complete closure of the AT is scheduled in accordance with the Sunnyside Consent decree. Several other adits, including the Terry Tunnel (1996), Lower Ransome adit (1998) on Eureka Creek, and the Sunbank (1993) and Gold Prince (1997) adits near the Animas headwaters have been sealed. Adits account for eighteen percent of the Zn concentration in the Animas at Silverton (A68) during base flow, but are not a significant part of the total concentration at other times, Figure 8.18. Cu and Zn from adits in Cement Creek are significant through base flow, but not during runoff. Sampling shows that a remarkably small percentage of the Al and Fe in Cement Creek comes from adits, Figure 8.19. However, two of the larger draining adits, the Grand Mogul and Mogul are above the AT, thus between 1996 and 1999 the AT plant removed metals from these mines during base flow. Figure 8.19 is based on data collected after the consent decree was implemented. Treatment of Cement Creek, which removed metals from both adits and ground water above the AT, between 1996 and 1999 lowered the average concentration of Cu and Zn at CC48 by 15 and 212 ug/1, respectively. Adits are responsible for the largest percentage of the Cd, Cu, and Zn in Mineral Creek most of the year. More than half of the Cd, Cu, and Zn are from two adits in the Red Mountain Pass area. The Paradise adit, on the Middle Fork of Mineral Creek and upstream of the “Red tributary,” contributes over half of the Fe in Mineral Creek during the winter months. The data show that adits are a minor source of Al in Mineral Creek, Figure 8.20. Seasonal Runoff Seasonal runoff includes overland flow and throughflow. It is identified by a decrease in solute concentration, accompanied by a steep increase in load and flow. Seasonal runoff that contacts incompletely weathered pyrite such as found in alluvial fans, eroding headcuts, waste rock, or mill tailings are sources of acid and metals. Metal loading from seasonal runoff may be attributed to natural, mine-related, and other human-related factors such as overgrazing, road cuts, or any other activity that accelerates erosion within the acid surface environment. Many factors determine the amount of metals that may be contributed to streams from mine waste in the Upper Animas Basin. Mine waste includes dump material deposited near mine- workings and mill-tailings. It is assumed that all metal loading from mine waste is contributed to the streams as part of both throughflow and overland flow. One factor is location of mine waste in relation to surface and groundwater. The potential for metal loading from mine waste is greatest in the spring during snowmelt and in late summer during thunderstorms. The load of Al, Cd, Cu, Fe, and Zn from Prospect Gulch in the Cement Creek watershed was observed to increase one or more orders of magnitude during September storm runoff conditions. The largest immediate increases in loads corresponded to areas where waste-rock dumps were in close proximity to the stream (Wirt and others, 2000). An intensive investigation of the Mayday mine waste pile in the Cement Creek watershed (Stanton, 2000) found the highest concentrations of Cu, Pb, and Zn were associated with secondary minerals at 2-3 meters depth. Large numbers of iron- and sulfur-oxidizing microbes, and secondary Fe minerals were found at depth in the waste dump indicating that metals are mobile in the sub-surface. Because water is available on a sporadic basis at the Mayday dump—and many other dumps in the basin—rates of weathering reactions and mineral dissolution are sporadic as well (Stanton, 2000). Composition and mineralogy of the host rock is another factor. Waste rock from mine workings driven through non-sulfide bearing minerals, has little acid producing potential. Workings driven on vein are major sources of acid rock drainage. Both types of material may be present in the same dump. Mill tailings have a higher acid generating capability because finely ground rock exposes more surface area to oxidation. Moreover, rock transported to the mills generally contained major ore bearing minerals such as pyrite, sphalerite, galena, and enargite which have the richest metal content and the highest acid generating potential. Early mill technology concentrated on recovery of gold and silver, which often left large quantities of the base metals in the tailings. Mill tailings have been relocated and consolidated to several areas along the Animas River, mostly within segment 3a. Mill tailings at the Mayflower Mill (Ponds 1-4) have been capped and revegetated in accordance with SGC’s mine reclamation plan. Mill tailings, from the South Fork of Cement Creek, were relocated to tailings pond #4 between 1990 and 1992. Data collected by SGC from the South Fork of Cement Creek (CC17) shows that relocation of this pile decreased the dissolved A1 and Fe concentration in South Cement Creek. SGC removed over 100,000 cubic yards of tailings from the Eureka floodplain in 1996 and relocated some of the historic mill tailings from Howardsville to tailings pond # 4 near Silverton in 1997. Waste rock from two sites near the top of Red Mountain Pass have been partially or completely remediated. SGC covered, amended and vegetated the Longfellow dump and relocated the Kohler waste rock pile to the Mayflower Mill #4 pond in 1996-97. ARSG, with the assistance of a 319 non-point source grant, is currently relocating the waste rock pile at nearby Carbon Lakes to Pond #4. ARSG participants leach tested composite samples of the upper six inches of surface waste of 157 mine waste piles. Details of investigations of mine waste contributions are found in Chapter X and Herron and others (1997, 1998, 1999, and 2000). In addition to the leach tests, surface area estimates of all mine waste areas larger than 100 square meters above A72 have been made from aerial orthophotographs. Surface area estimates indicate that mine wastes covers about 0.15 percent of the area above A72. The contribution of metal load from the piles can be estimated by applying annual throughflow and overland flow estimates to the surface areas of the waste rock piles and by using the results of the leach tests. Throughflow and overland flow was computed by comparing the annual discharge from the Basin during 1996-99 to the acreage of the drainage (29 inches yearly). The annual metal load from waste rock expressed in pounds per year and as a percentage of seasonal runoff is summarized in Table 8.6. Table 8.6 Comparison of loads of individual metals from mine waste rock m the Upper Aminas Basin to total seasonal runoff loads at the pages. Loads_g[g_gL£2H5SLESLi!^gL-.------— Waste Pile Area(ac) A1 Cd Cu F e _ _ _ M n _ _ 2 n —__ 2,902 4,386 5,438 Animas 7973 895 33 506 39,479 1 14,233 Cement 26.6 2,432 86 1,611 32,548 1,753 2,102 Mineral 28.5 2,437 19 296 Watershed Area (ac) Metal Loads from Seasonal Runoff in Pounds per Year 35,604 169 2,703 100,163 141,264 91,242 Animas (A68) 45,184 Cement (CC48) 12,864 85,338 128 4,456 646,383 18,828 42,273 Mineral (M34) 33,536 . 64,571 49 1,348 125,533 8,815 19,672 % of Area Percent of Seasonal Runoff from Dumps Animas 0.176% 2.5% 19.6% 18.7% 2.9% 3.1% 6.0% Cement 0.206% 2.8% 67.1% 36.2% 6.1% 0.0% 33.7% Mineral 0.085% 3.8% 38.1% 21.9% 25.9% 19.9% 10.7% The basins largest tailings repositories are currently the permitted sites at the Howardsville and Mayflower Mills east of Silverton. Since these sites are permitted and already have runoff controls or have been reclaimed, they were excluded from calculations for total waste rock contributions. Metals from waste rock, distributed across the seasonal runoff period as a percentage of the total seasonal runoff and total metal concentration, are shown in Figures 8.18 to 8.2a Zn is the predominate solute from seasonal runoff in the Animas River a b o v e Silverton (Figure 8.1 ). Analysis of the dissolved concentration data in segment 3a indicates that most of the Zn from seasonal runoff enters the river between Arrastra Gulch.and the gage at A68. Most of the Cd, Cu, and Mn, not shown, are attributed to seasonal runoff in the same reach as the Zn. Seasonal loading is most apparent in Cement Creek. Unlike other metals found in the streams in the Basin, the highest concentration of Cu occurs in conjunction with high streamflow (Figure 8.19). Seasonal runoff also produces more Al, Fe, and Zn in Cement Creek than in the Upper Animas or Mineral Creek basins. Seasonal runoff as a source of solutes in Mineral Creek is the least of the three sub-basins. A very small proportion of the Al and Fe in Mineral Creek is from seasonal runoff (Figure 8.20). M onth Legend Waste Rock — Base flow Adit ^ **1—^ Undifferentiated Seasonal Runoff Figure 8.18a Seasonal, flow-based sources of total recoverable aluminum and iron to A6 8 , the Animas River at Silverton, estimated from the water quality regression model. Stream flow is the average monthly flow at A6 8 , 1993 to 1999. Calculated values are forthe 15th day of each month. $ I— > I V - A L e g a n t To tal Recoverable Cu < I o Figure 8.19b Seasonal, flow-based sources of total recoverable cadmium, copper, manganese, and zinc to CC48, Cement Creek at Silverton, estimated from the water quality regression model. Stream flow is the average monthly flow at C C 48,1993 io 1999. Calculated values are for the 15 day of each month. Conctntratioa In ug/} Legend Total Recoverable Cd Month Figure 8.20b Seasonal, flow-based sources of total recoverable from the water quality regression model. Stream flow is the average monthly flow at M34, y each month. Combined Effects in the Animas River below Silverton One of the goals of the UAA is to estimate the water quality that could be achievable in the Animas River below Mineral Creek if “reversible5’ sources of metal loading were remediated. Sources of metals measured at A72 are from the three sub-basins discussed above. Each of the sub-basins contributes a differing amount of stream flow based on the area of its watershed. The concentrations of the different metals and their sources, groundwater, adits, and seasonal runoff are different for each of the sub-basins. Figure 8.20 combines the solutes and their sources to show their combined effect at A72, the Animas River below Silverton. Nearly all of the total recoverable A1 measured at A72 can be attributed to groundwater sources. Concentrations are highest in the winter when stream flow is the least. Figure 8.14 shows that most of the Ai is in colloidal form by the time it reaches A72. However, the concentration of dissolved Al exceeds chronic toxicity criteria (87 ug/1) for trout species for over four months of the annual cycle. Groundwater, adits, and seasonal runoff affect the total recoverable Fe concentration at A72. The Fe concentration is highest during winter low flow with about two-thirds coming from groundwater. Groundwater sources of total recoverable Fe exceed aquatic life criteria (1000 ug/1) for over nine months of the year, Controlling sources of Fe from adits and seasonal runoff could improve water quality, but TVS criteria could not be met most of the time. Groundwater, adits and seasonal runoff are all sources of total recoverable Zn at A72. Total recoverable and dissolved Zn concentrations at A72 are nearly identical (See Figure 8.17), therefore Figure 8.21 also represents sources of dissolved Zn. Zn levels could be substantially reduced if sources from adits and seasonal runoff were controlled. Owing to winter contributions from ground water however,, it is unlikely that acute and chronic TVS criteria can be met at A72 during the months of October through April. Figure 8.21 indicates that more of the total recoverable Cu at A72 is from adits and seasonal runoff than from ground water. Dissolved Cu has been suggested as a possible limiting factor for brook trout (Besser, 2000), Controlling sources of Cu from adits or seasonal runoff should enable the segment to meet this aquatic life criteria. Other Human Impacts: Other human activities in the basin have the potential to impact water quality, especially within the acid-sulfate and quartz-sericite-pyrite regions of Cement and Mineral Creek watersheds. Exposure of fresh sulfide minerals to air, water, and microbial action are especially critical because it could increase the production of acid water and higher metal loads in nearby streams. Roads used to reach the mine sites and for recreation use are potential sources of metals loading. Alpine sections of the headwaters of the Animas, Mineral, and Cement Creeks have grazing allotments for sheep. Accelerated erosion, caused by improper grazing, is one mechanism that could lead to additional acid water production in selected areas. The acidity of the precipitation can also be an influential factor by helping to create conditions favorable to acid rock drainage. Bacteria necessary for this catalytic reaction, which then releases even more acid into the environment, begins to flourish if the fluid acidity is below a pH of 5.5. The average pH of precipitation at Molas Pass (five miles south of Silverton) from 1986 through 1993 was recorded by the National Atmospheric Depositional Program as 5.0. This low pH, coupled with low available alkalinity though out the caldera could add to the natural and human-induced acid drainage. Silverton discharges about 0.2 cfs of municipal wastewater to the Animas River above Mineral Creek. ARSG sampled a major sewer main at two locations and the inflow into the treatment facility. Cadmium, copper, lead, manganese, and zinc were all found at concentrations lower than concentrations found in the river. The wastewater treatment plant is not a significant source of metals. Cold, swift water of the Animas minimizes the potential for DO problems. Similarly, low water temperature and low pH in the Animas also minimizes any potential for unionized ammonia. Fecal coliform from the wastewater plant could affect recreational use of the river, however recreational use is confined to high flow periods when dilution is maximal. REFERENCES Besser, John. 2000. USGS. Personal communications; Results of biotoxicity study on brook trout using Animas River water. Results to be published winter of 2000-01. Cady, T., B. Horn, R. Owen, B. Simons, B. Stover. 1996. Reconnaissance of the Animas Canyon (August 16-18,1995). Colorado Water Quality Control Commission. 1999. "The Basic Standards and Methodologies for Surface Water" 5CCR 1002-31. CDPHE. Farrell, Camille M. S. 1997. Comprehensive Analytical Results Report Cement Creek watershed\ San Juan County, Colorado. Colorado Division of Hazardous Materials and Waste Management; CDPHE. Farrell, Camille M. S. 1997. Site inspection sampling activities report Upper Animas watershed, San Juan County, Colorado. Colorado Division of Hazardous Materials and Waste Management; CDPHE. Helsel, D. R. and Hirsch, R. M. 1995. Statistical Methods in Water Resources. Elsevier, Amsterdam. Herron, J., Stover, B., Krabacher, P., and Bucknam, D. 1997. Mineral Creek feasibility investigations report, upper Animas River basin. Colorado Division of Minerals and Geology. Herron, J., Stover, B., Krabacher, P., 1998. Cement Creek reclamation feasibility report, upper Animas basin. Colorado Division of Minerals and Geology. Herron, J., Stover, B., Krabacher, P., 1999. Reclamation feasibility report, Animas River above Eureka. Colorado Division of Minerals and Geology. Herron, J., Stover, B., Krabacher, P., 2000. Reclamation feasibility report, Animas River below Eureka. Colorado Division of Minerals and Geology. Kimball, B. A., Runkel, R.L., Walton-Day, K., Bencala, K. E. 2000. Assessment o f metal loads in watersheds affected by acid mine drainage by using tracer injection and synoptic sampling: Cement Creek, Colorado, USA. (in press). Kimball, B. A., Schemel, L. S., Cox, M. J., and Gemer, L. J. 2000, Loading and Chemical Reactions metals entering the Animas River between Silverton and Elk Park, San Juan County, Colorado, (in press). Kinball, B. A. 2000. Personal communication. U. S. Geological Survey. Knighton, David. 1984. Fluvial Forms and Processes. Edward Arnold, Publisher. M cIntyre, Susan. 2000. Personal communication. CDPHE. WQCD. Nordstrom, D. K., Alpers, C. N., Coston, J. A., Taylor, H. E., McCleskey R. B Ball, J. W , Ogle S Cotsifas, J. S. and Davis, J. A. 1999. Geochemistry, toxicity and sorption properties o f contaminated sediment and pore waters from two reservoirs receiving acid mine drainage. U. Geological Survey Water Resources Investigations Report 99-4018A. Owen J R 1997. Water quality and sources o f metal loading to the upper Animas River basin. M o Department of Public Health and Environment, Water Quality Control Division. Paschke S.S., Kimball, B. A., and Runkel, R. L. 2000. Quantification and simulation o f metal loading to the upper Animas River, Eureka to Silverton, San Juan County, Colorado, September 1997 and August 1998. (in press). Perrino, Larry. 1999. Personal communication. Sunnyside Gold Corporation. Schemel. L. E., Kimball, B. A., and Bencala, K. E. 1999. Colloid formation and the transport o f aluminum and iron in the Animas River near Silverton, Colorado. U. S Geological Survey Water Resources Investigations Report 99-4018A. Stanton, M. R. 2000. The role o f weathering in trace metal redistributions m theM ayday Mine dump near Silverton, Colorado. U. S. Geological Survey Open-File Report 00-034. Vincent, K. R, Church, S. E., and Fey, D. L. 1999. Geomorphologicalcontext o f metal-laden sediments in the Animas River fioodplain, Colorado. U. S Geological Survey Water Resources Investigations Report 99-4018A. U .S. Geological Survey, 2000, Interim report on the scientific investigations in the Animas River watershed, Colorado to facilitate remediation decisions by the U.S. Bureau o f Land Management and the U.S. Forest Service, March 29,2000 Meeting, Denver, Colo., U.S. Geological Survey Open-File Report 00-245,34 p. Water Quality Control Division. 1994. Exhibit 3, Upper Animas Water Quality Classifications and Standards Proposal. Colorado Department of Public Health and Environment. Wirt, L., Leib, K. J., Mast, M. A., and Evans, J. B. 2000. Chemical-constituent loads during thunderstorm runoff in a high-altitude alpine stream affected by acid drainage. U.S. Geological Survey Open-File Report 00-034. Yager, D. B„ Verplank, P. L„ Bove, D. J., Wright, W. G„ and Hageman P. L. 2000. N atural versus mining-related water quality degradation to tributaries draining Mount Moly, Silverton, C olo. U. S. Geological Survey Open-File Report 00-034. Appendices Appendices to Chapter VIII are Microsoft WORD and EXCEL 97-98 files that contain the data and analyses used for the UAA. Following is a brief description of the files in the Appendices. A p p en d ix 8 A: Contains the water quality data collected from streams and adits by the USGS, WQCD, DMG, USFS, BLM, CDOW, and the ARSG from 1991 through September 3 0 ,1 9 9 9 . Cement Creek.xls Mineral Creek.xls Upper Animas.xls Lower Animas.xls A p p en d ix 8 B: Contains spreadsheets used to calculate acute and chronic table value standards and the 85th percentile concentrations at selected main stem locations. Ac/Ch TVS.xls Arrastra.xls PH.xls Seg_2.xls Seg_3a.xls Seg_4a.xls Seg_4b.xls Seg_7.xls Seg_8 .xls Seg_9b.xls A p p en d ix 8 C: Contains an MS WORD document, WQRM.doc, that describes the regression approach for the WQRM. Also contains the data, statistics, and regression equations for dissolved and total recoverable Al, Cd, Cu, Fe, M n, and Z n at the four gaging stations used for the WQRM Regression equations for dissolved metals A 6 8 D R EG .xls A72DREG.xls CC48DREG.xls M34DREG.xls A 6 8 TREG.xls A72TREG.xls CC48TREG.xls M34TREG.xls And the following worksheets showing the partitioning of total loads into groundwater adits waste rock, and undifferentiated seasonal runoff for each of the gaging stations: A 6 8 _Sour.xls A72_Sour.xls CC48j3our.xls M34_Sour.xls APPENDIX 8A WATER QUALITY DATA FOR STREAM AND DRAINING ADITS ANIMAS WATERSHED SPREADSHEETS USED TO CALUCULATE ACUTE AND CHRONIC TABLE VALUE STANDARDS AND THE 85™ PERCENTILE CONCENTRATIONS AT SELECTED MAIN STEM LOCATIONS APPENDIX 8C DESCRIPTION OF WATER QUALITY REGRESSION METHOD (WORM) (Data, Statistics, and regression equations for dissolved and total recoverable metals are available on the UAA CD ROM only) In tro d u c tio n The concentration of solutes—metals— sampled in the upper Animas Basin sometimes vary over an order of magnitude or greater at any single station. The 85 percentile methodology used for setting standards shows the frequency a certain value is likely to be exceeded, but does not account for environmental variables that influence concentrations and affect designated uses. Observational data from the four stream gages stations in the upper Animas Basin shows that the concentrations of many of the solutes are associated with stream flow. Moreover, solute concentrations vary per unit of stream flow depending on the season of the year. This is most apparent during the first flush associated with the onset of spring runoff in areas affected by mine wastes. Using the ^ relationship between solute concentration and other variables that affect the concentration increases the information that can be extracted from the data, Regression analysis is a common method for assessing these relationships. Through regression we can: • Summarize a large quantity of data; • Estimate the duration that a solute is likely to exceed a chronic or acute aquatic life criterion; ® Estimate whether water quality standards are likely to be exceeded under drought, flood, or normal stream flow periods; • Adjust data obtained under varying stream flows to a common base; • Obtain greater sensitivity to evaluate if actions in a watershed are changing water quality; and • Construct a mathematical model to predict the amount of change that might occur owing to remediation. Regression, as used in this report, deals with average conditions. It is does not predict or model single events such as an individual rainstorm or flood event. All of the variables must be measured in some manner, and measurement involves error. Random variation, error, is present in the quantification of solute concentration, discharge measurements and other environmental variables that are measured. Regression deals only with the random error in the response variable, solute concentration. M ultiple regression assesses the strength of the relationship among variables. The regression method involves one response variable, solute concentration, and one or more predictor variables, stream flow and time of the year. The method requires that a mathematical model be specified that describes how the variables of interest are related to one another. The method also requires that the response and predictor variables be linearly related. Hydrologic variables are usually not linearly related. For example, a data plot of solute concentration versus stream flow typically is the shape of a hyperbola. Seasonality is a cyclical phenomenon that resembles a sine wave and repeats itself yearly. Transformations are used to achieve linearity between response and predictor variables. A transformation changes the scale of the variable. A temperature value in degrees Fahrenheit ( F ) can be transformed to Celsius ( C ) scale using the equation: C - 5/9(F - 32). The new scale ranges from 0 to 100 instead of 32 to 212, but the physical property of temperature remains the same. Transformations can introduce bias into the response variable when the transformed variable is converted back to its original value. This affects the error term (standard deviation) and values calculated on values in the original units. Transforming only the predictor variables avoids this problem. Traditionally the logarithmic transformation was used to linearize the relationship between concentration and stream flow. A second transformation, which avoids taking the log of the response variable (concentration), is the hyperbolic form where a new stream flow scale is created using Q = U ( \+ B @ The term, B, is a constant within the range 0.001 to 10 which maximizes the K2 betw een stream flow (Q’) and concentration. Seasonality is modeled using sine-cosine pairs for the day of the year expressed as the julian date (1-Jan ~ 1; 31-Dec - 365). The cosine term is added to place the annual maximum and minimum at the correct time of the year. The form of the transformation i s : sin((6.23*365)x juliandate) cos((6.23*365)x juliandate) where 6.23 is 2FT radians. Additional sine-cosine pairs can be added using different periods. Many of the regressions were improved using a semi-annual period (182) days in addition to the annual period. A binary (0 ,1 ) variable was also included in the regression model to test whether a solute concentradon changed between two time periods. The Sunnyside Consent Decree and some remediation began about October 1, 1996. Data collected before October I, 1996 was coded 0 and 1 if after October 1, 1996. A positive coefficient means solute concentration increased and a negative coefficient means there was a decrease in concentration. The formulation of the transformed model is: C = b + axQ +a2X 2 + azX^ + a4X 4 -t- a5X 5 + a6X6 + s where : C - solute concentration b - intercept a* = calculated coefficients for each variable Q’ = transformed stream flow X2 - sine((6.23/365)*julian date) X3 = cosine((6.23/365)*julian date) X4 = sine(6.23/182)*julian date) X 5 - cosine(6.23/182)*julian date) X6 = 0 or I for pre- or post-remediation s - error or variance not explained by the model The regression analysis was done using the step-backward procedure. This procedure uses the full model ( Q’ through Xe) and systematically eliminates each variable to determine the effect on R 2 The sine-cosine terms were always deleted in pairs. If the eliminated variable(s) did not reduce the R2, then it was determined that the variable(s) did not contribute to the explanation of variance of the response variable and it was dropped from the final model. The regression model was used only for target solutes where fewer than about 10% of sample observations were recorded as less than detection. Concentrations less than detection were set at 1/2 the reported detection limit. R esults The variance of solute concentrations was reduced (p < .01) at all sites with one or more of the predictor terms in the model at A 6 8 , CC48, M34, and A72 for hardness and dissolved Al, Cd. Cu, Fe, Mn, and Zn. Dissolved Al, and Fe models were not done at A 6 8 because too many observations were reported as less than detection. Similar results were obtained for total recoverable Al, Cu, Fe, and Zn at all four gage sites. The R values percent of the variance in solute concentration explained by the terms remaining in the model, ranged from 0.19 (Cd at A72) to 0.87 (Al at CC48). The R2 for total recoverable ranged from 0.27 (Al at A 6 8 ) to 0.87 (Al at A72). The R is a useful value for evaluating regression results, but it can be misleading. Solute concentrations that vary over a narrow range may have smaller R2than solutes that vary over a wide range. The most apparent example in the upper Animas Basin is the Zn concentration at CC48. The R2’s for both dissolved and total recoverable are a relatively low 0.22 and 0,34, respectively. However ratio of the standard error, or variance that is unexplained by the model, to the mean concentration shows that dissolved and total recoverable Zn at CC48 have two of the lowest ratios of any of the solutes evaluated. Cd was one of the few solutes that did not correlate with stream flow or season. Differences in Cd levels were shown for the pre- and post- October 1, 1996 time periods. The pre- and post-remediation coefficients were significant for Cd and Zn at CC48 and CuandZnatM34. A Including one or both of the sine-cosine pairs in the model improved the R ’s in most cases. Total recoverable A1 in Mineral Creek at M34 was the only one to correlate with Q’ and none of the sine-cosine terms. This suggests that seasonal factors, other than runoff dilution, influence solute concentration in these streams. The total recoverable A1 result at M34 is also interesting. One of the properties of the hyperbolic model is that is that the product of the xy terms, or in this case the QC terms, is a constant. This suggests that the source of the A1 load, which is QC, is constant and the concentration, C, is affected only by dilution, Q. Regression coefficients and statistics for dissolved and total recoverable are found in spreadsheets for the four gages in Appendix 8 C. References Helsel, D. R. and Hirsch, R. M. 1995. Statistical Methods in Water Resources. Elsevier Press. Kleinbaum, D. G., Kupper, L. L., and Muller, K, B. 1988, Applied Regression Analysis and Other Multivariable Methods. PWS-Kent Publishing Co. CHAPTER IX BIOLOGICAL POTENTIAL AND LIMITING FACTORS ANALYSES FOR IMPAIRED STREAM SEGMENTS B ACK G RO U N D AND S C O P E ______ LIMITING FACTORS ANALYSIS______3 Theory Behind Limitine Factors 3 METHODS 3 D ata Used 3 Fram ew ork 4 Renthic Macroinvertebrates 4 Alyae. funai and other life forms 4 FACTORS DISMISSED AS NON-LIMITING 5 Physical parameters 5 A nchor Ice 5 Access ('barriers/impediments) 5 Periphery of Ranee 5 Water Ouantitv (space & flow regime) 5 Water Temperature 6 Cover (considered for fish) 6 Total Suspended Solids CTSS) 6 Chemical Parameters 7 Dissolved Oxveen 7 Organic Compounds 7 Total Suspended Solids CTSS) 7 Inorganic Elements and Compounds (surface water) 8 Antimony 8 Arsenic 8 Barium 9 Bervllium 9 Bism uth 9 Roron 9 Rrnm tne 9 Calcium 9 Chloride 9 Chromium 9 Cobalt 9 Cyanide 9 Fluoride 9 Gallium 10 Lithium 10 Nickel 10 M erciirv 1 0 M olybdenum 10 Phosphate 10 Potassium______10 Selenium ______iq Silicon______10 Silver ______11 Sodium ______11 Sulfate______11 T!n — ..... i i Titanium______11 Vanadium ______\ \ Zirconium______\ j Nitrite+Nitrate______\ \ Ammonia 1 [ TSS ______„ Biological Parameters ______12 Predation______J 2 Disease/Parasites,______\ 2 Competition______12 Forage Fish ______12 Bioaccumuiation ______•______\ 2 ANALYSES OF PROBABLE LIMITING FACTORS______13 Chemical Parameters ______\ 3 Acidity and Alkalinity (as measured by pH units)______13 Dissolved M etals______.______13 Metals in the Solid State______j 4 Hardness (as Calcium Carbonate equivalent)______14 Sediment Pore Water Quality ______14 Physical Parameters ______\ 4 Fish Habitat ______\ 4 Macroinvertebrate Habitat______14 Precipitate Accumulations______15 Biological Parameters ______j 5 SEGMENT BY SEGMENT ANALYSES OF POTENTIALLY LIMITING FACTOR ------;------16 Segment 2 (Animas River Above Minnie Gulch) ______16 Aquatic Species Present______15 Location of Determination of Chemical Parameters______16 Limiting Factors Table______■ ______15.17 Summary______17 Segment 3a (Animas River between Silverton and Minnie Gulch)______17 Aquatic Species Present ______17 Location of Determination of Chemical Parameters______17 Limiting Factors Table______18 Summary______19 Segm ent 3b (Animas River between Cement and Mineral Creek)______20 Aquatic Species Present______20 Location of Determination of Chemical Parameters______20 S um m ary______20 Segment 7 (Cement Creek basin)______20 A quatic Species Present ______20 Location of Determination of Chemical Parameters______20 Limiting Factors Table ______20 S um m ary______22 Segm ent 8 (Mineral Creek above South Fork of Mineral Creek)______22 A quatic Species P re se n t______22 Limiting Factors Summary______,______22 Limiting Factors Table______22 S um m ary______23 Segm ent 9 b ______24 Location of Determination of Chemical Parameters______24 Limiting Factors Table ______24 S um m ary______25 Segment 4a ______25 Aquatic Species Present ______25 Location of Determination, of Chemical Parameters______25 Limiting Factors Table ______25 S um m ary______27 Segment 4b ______27 Aquatic Species Present______27 Location of Determination of Chemical Parameters______27 Limiting Factors Table ______28 S um m ary______28 SU M M A RY O F L IM IT IN G FA CTO RS A N A L Y S E S ______29 BIOLOGICAL POTENTIALS IF IDENTIFIABLE MINING IMPACTS WERE NOT PRESENT ______30 SEGMENT 3 A - ANIMAS RIVER ABOVE SILVERTON ______33 SEGMENT 7 - CEMENT CREEK ______36 SEG M EN T 9B - L O W E R M IN ERA L C R E E K ______39 SEG M EN T 4A - ANIM AS R IV E R BELO W S IL V E R T O N ______42 SEGMENT 4B - ANIMAS BETWEEN ELK PARK AND JUNCTION CREEK ______44 R EFER EN C ES ______46 Table 9,1 Comparison of the protectiveness of Table Value Standards in Animas stream segments to Biological Thresholds (TVS) for 3 species of trout. ______31 FIGURES Figure 9.1 Existing Stream Classifications, Animas River- Upper Basin Figure 9.2a Comparison of Segment 3a (Animas) Non-Mining Concentrations to Table Value Standards for Al, Cd, Cu, and F e.______3 4 Figure 9.2b Comparison of Segment 3a (Animas) Non-Mining Concentrations to Table Value Standards for Mn and Z n.______3 5 Figure 9.3a Comparison of Segment 7 (Cement Cr) Non-Mining Concentrations to Table Value Standards for Al, Cd, Cu, and Fe. ______37 Figure 9.3b Comparison of Segment 7 (Cement Cr) Non-Mining Concentrations to Table Value Standards for Mn and Z n.______3 g Figure 9.4a Comparison of Segment 9a (Mineral Cr) Non-Mining Concentrations to Table Value Standards for Al, Cd, Cu, and Fe.______4 0 Figure 9.4b Comparison of Segment 9a (Mineral Cr) Non-Mining Concentrations to Table Value Standards for Mn and Zn. ______41 Figure 9.5a Comparison of Segment 4a (Animas Cr) Non-Mining Concentrations to Table Value Standards for Al, Cd, Cu, and Fe.______43 Figure 9.5b Comparison of Segment 4a (Animas) Non-Mining Concentrations to Table Value Standards for M n and Z n .______44 CHAPTER IX: BIOLOGICAL POTENTIAL AND LIMITING FACTORS ANALYSES FOR IMPAIRED STREAM SEGMENTS This chapter is designed to determine what factor(s) currently limit aquatic life in impaired segments of the Animas watershed and to determine the biological potential of those segments given only natural limiting factors. The limiting factors analysis relies upon the synthesis of water quality, physical habitat, and biological conditions described in earlier chapters of this UAA. It will also provide insight into possibilities for the creation of diverse populations of aquatic biota in streams impacted by mining activities. Recommendations for limiting factor reductions that will yield desirable aquatic communities are addressed in Chapter XI, where remediation scenarios and anticipated biological outcomes are presented. BACKGROUND AND SCOPE In 1995, to become effective in June, 2001, the state's Water Quality Control Commission adopted an upgraded, goal-based classification, aquatic life class 1, for Segment 4a of the Animas River (Figure 9.1). Also effective in 2001, the Commission upgraded Segment 9b of Mineral Creek to aquatic life class 1. Along with numerical standards for metals and pH, the classifications require that class 1 streams support "a wide variety of cold water biota, including sensitive species and trout." To what degree these streams are capable of supporting aquatic life has become a fundamental management question. Stream segments 3a and 4b of the Animas are also impaired by metal contaminants and are classified as Cold Water Aquatic Class 1. It is necessary to determine the biological potential of these stream segments as well, in order that appropriately protective and achievable stream standards may be implemented. In addition, Segments 3b and 9b are heavily impacted by dissolved and colloidal metals. Segment 3b's lack of aquatic life classification remains uncontested but standards of "ambient" water quality were recently disapproved. Segment 9b was recently upgraded to Cold Water Aquatic Class I but the EPA disapproved the standard for zinc. Therefore stream segments 3a, 3b, 4a, 4b, and 9b will all be addressed in the following limiting factors analyses. Stream segment 2, segment 7, and segment 8 have such overwhelmingly "irreversible" amounts of metal contamination and/or low pH that the EPA has accepted the WQCC's setting of ambient water quality standards with no aquatic life use. These segments will not be analyzed in this chapter since ARSG evidence supports their present status. However, LFA tables for these segments have been included in Appendix A for reference purposes and for future comparison to the downstream segments. Reduction of all metals may not in itself allow for healthy invertebrate populations and self-sustaining fisheries. It is possible that other factors, such as physical habitat, may play an equally important role in structuring biological components. Reducing all metals may be unnecessary, impractical, and perhaps undesirable. A comprehensive limiting factors analysis can reduce the risk of erroneous conclusions and poor decisions. Theory Behind Limiting Factors The fundamental concept behind any habitat reclamation or enhancement is that reproduction growth and/or mortality are affected by discrete physical, chemical, or biological factors (limiting factors). A limiting factor is defined as any physical, chemical, or biological component that impedes the survival or rate of growth of an organism or population (Hunter 1991). Limiting factors differ among species and life stages, and change over space and time. They are always present; when one limit is relieved, another comes into play (Mehan, 1991), An often cited model for describing limiting factors is the "bottleneck theory", where a single factor is shown to constrain a specific life stage of an organism and subsequently dictates population size and structure. While somewhat descriptive, it should be recognized that this model is a gross oversimplification of a complex set of ecological processes (Mehan, 1991). While there are numerous techniques and models that allow for relatively precise quantification of physical and chemical attributes, the real challenge is in the translation of these factors into biological reality. We know that population regulation occurs through a variety of mechanisms, many of which are interrelated. Also, influencing factors may vary in time and space, making it difficult to identify the group of factors controlling long-term population size and structure. The cumulative and synergistic potential of numerous factors may also prove problematic. To illustrate, there have been four long-term (15+ yr, scientific studies of salmonid populations designed to precisely identify limiting factors. None of these studies have been able to identify, with certainty, the most important limiting factors for the populations studied (Bisson’ unpublished). While it may not be possible to identify the limiting factors in a manner that satisfies the rigors of scientific research, we can conduct evaluations that provide answers that will reduce the risk of erroneous conclusions and poor decisions. This LFA has been conducted by a group of biologists (ARSG Biology Work Group) and other scientists who have long been involved with the collection and analysis of data in the Animas watershed. Since the ecological parameters being analyzed are generally complicated and inter-related, determinations will be made using "best professional judgement" by this group. METHODS The analysis is based on an evaluation of physical, chemical, and biological parameters for each life stage of each species (trout) or group of species (macroinvertebrates) being considered. Data Used This analysis will draw upon the data and interpretations presented in earlier chapters of this UAA. They include the recent and historical biological and physical investigations that were presented in Chapter VI as well as the metal loading analyses presented in Chapter VIII (Tables 8.2 a - 8.2e. Although much information and many discussions have lead to the conclusions presented as to the factors having the highest potential as limiting, the summary information provided in Chapter VI was most heavily drawn upon. Summary schematic Figures 6.1 through Figure 6 .8 provided in Chapter VI were used in making these determinations Since a limiting factors analysis interprets what may limit life, biological thresholds to toxicity are used rather than stream standards for the evaluation. However, very little useful information exists on biological thresholds for many trace elements (e.g. boron, gallium, etc). W here biological thresholds are not known, EPA criteria (suggestions) or Table Value Standards (regulations) are used in this analysis. They are noted as such. Framework The assessment is based on an evaluation of physical, chemical, and biological parameters for each life stage of each target species. The evaluated species are listed at the beginning of each stream segment. This analysis utilizes “biological thresholds” which are species specific tolerances for metal concentrations. These thresholds have been determined by reviewing EPA criteria and recent research results. A thorough comparison of biological thresholds to Table Value Standards (TVS) is presented in the Biotoxicity Report (TVS are mistakenly referred to as stream standards), Appendix VI-C. Literature references for biological criteria are provided in that report. The biotoxicity report can be used to determine if Table Values Standards (TVS) are protective, or over protective, of the particular species for which one is managing (e.g. brook trout). Table 9.1, presented later in this chapter is a summary of the comparison between biological thresholds and Fish: Biological and physical parameters and biological thresholds for most metals have been established for brown, brook and rainbow trout. Because of the consistancy in results and extensiveness of biotoxicity testing for trout, combined with their position at the top of the food chain, they are used as the primary indicator species for this limiting factors analysis. Cutthroat trout are considered to have biological thresholds for metals similar to those of rainbow trout and therefore are treated as equals in this respect. Little is known about biological thresholds or other conditions necessary to sustain a sculpin fishery, therefore an analysis is not presented for this native species, although it is thought to be a resident in South Mineral Creek and lower Segment 4b. This fish may also prove to be a good indicator species for Segment 3a, since this segment is within its normal range and water quality conditions already approach Table Value Standards for most metals. Re-introduction should be considered. Benthic Macroinvertebrates Conditions necessary for successful benthic macroinvertebrate populations and limiting factors are less well understood. Some basic assumptions will be applied to narrow the field of what might be considered limiting factors. In general, trends related to liming factors seen in trout populations may also be evident in macroinvertebrate populations. Summaries will include discussion of possible similarities in responses to limiting factors between these two groups. Algae, fungi and other life forms: In general, this report provides minimal evaluations of factors that might be limiting algae, fungi, and other life forms due to the lack time, funding, and knowledge of specific life cycle requirements Several factors can be dismissed as non-limiting. These include factors that remain within the normal range of aquatic life; elements that are essential for aquatic life and are in the system in beneficial concentrations, and factors that are either not present in minimal concentrations and/or duration in the system. Factors that are necessary for aquatic life in general (e.g. water) have been considered but none have been identified to be absent. Physical parameters (for fish and macroinvertebrates) A nchor Ice Anchor ice was considered to be a marginal limitation due to the available recruitment macroinvertebrate communities. Anchor ice probably does occur but is not the limiting factor inhibiting aquatic life in the mainstem of the Animas and major tributaries. Access (barriers/impediments^ There is an access issue from an historical perspective. Comments have been received claiming that a barrier (waterfall) exists in the lower Animas that inhibits fish access to the Upper Animas. The argument is that historically fish may not have existed, and therefore they should not be required at this time. We find this argument irrelevant to this task. Fish populations presently occur within the upper basin at several locations. No physical barriers exist that would preclude fish from being established in any segments although several stream segments may be isolated by poor water quality in streams to which they flow. Initial stocking may be necessary in these specific instances. Periphery of Range Periphery of range is an issue of large-scale population viability. Trout populations are well established throughout the Rocky Mountain region at similar elevations, including the San Juan Mountains. There is no periphery of range issue associated with the upper Animas watershed for rainbow, cutthroat and brook trout. Brown trout have a lower elevation range than the other species but they are known to migrate to spawning areas at elevations exceeding 1 0 ,0 0 0 feet. Geochemical barriers to migration could exist in the mainstem of the Animas and Upper Basin tributaries. Water Quantity (space & flow regime) The amount and timing of flow available within some of the Animas tributaries may be a primary limiting factor for fish. This is typical of headwater streams within the region. However, stream gauge data at the mouth of the Upper Animas (A6 8 ), Mineral (M34), and Cement Creeks (CC48) indicate that Segments 3a, 3b, 9b, 4a and 4b are not constrained by low or high stream flows at any time. Historical flow measurements from the Howardsville gauge confirms this premise. Upper elevations of Segments 2, 7, and 9a (or other smaller tributaries) may have constraints where stream size is quite small and/or where gradients are very steep. Assuming water quality remediation occurs, the quantity of flow and physical space available may become influential, but does not presently preclude or constrain aquatic life within known mainstream segments. W ater Temperature Temperature data collected over numerous years indicate there is no problem with lethally high water temperatures (>12C). The presence of fish in tributaries and downstream of Segment 4a supports the conclusion that high temperature is not limiting. Low temperatures, in combination with short growing seasons, have been know to inhibit year class recruitment in some of the region's high elevation streams. However, such situations typically allow for populations to be sustained at some level. Since healthy populations occur upstream at higher elevations and at very low stream flows (e.g. South Mineral above the Bandora mine), we are willing to assume that low temperature does not significantly inhibit aquatic life. Temperature data for most water quality samples are included in the ARSG database. Cover (considered for fish) Streamside cover, riparian vegetation, has been drastically reduced in many high elevation locations above Silverton and below Baker's bridge in the Animas valley and beyond. Grazing of livestock has removed much of the willows in the Upper Basin while grazing, gravel mining, and urban development has removed much of the riparian elements in the Lower Basin (from photographs and personal experience). This is less true in the Animas canyon where grazing and development have been minimal. Where fish populations exist in the watershed, cover is occasionally lacking. Though streamside cover is limited in many segments of the Upper Basin it is not considered the limiting factor, although it is probably influential in fish community structure and numbers. Therefore streamside cover will be discussed as a limiting factor only where it is obviously quite important. In-stream cover is minimal in locations of low stream gradient, which are few. Generally this is not a factor limiting trout but may significantly influence population density. Only where it is a significant factor will it be further evaluated in the Limiting Factors Tables, Total Suspended Solids (TSS) Non-specific suspended solids as a result of soil erosion and sediment transport are not considered a limiting factor in the Upper Animas, Animas canyon, or tributaries of these watersheds. Data was not collected on TSS but observations of suspended solid conditions plus the existing distribution of fish and lack of major erosion areas precludes this from having a high or moderate potential as a limiting factor. Colloids (a part of TSS associated with metal loading) should not be summarily dismissed however. Colloids (metal precipitates) will be evaluated for potential as a limiting factor for all segments. Chemical Parameters Dissolved Oxygen We are willing to assume is that oxygen is not limiting since nearly all streams are high gradient and analyses have shown saturated levels of oxygen common and within aquatic life requirements at all times of year. The exception would be directly below springs and draining mine adits. Organic Compounds During the Cement Creek synoptic characterization sampling of contaminant sources, EPA ran parallel analyses on six aqueous samples (10% of DMG's surface water samples) for Pesticides/Polychlorinated Cyanide and Total Organic Carbon (TOC) analysis. Six sediment samples collected were also analyzed for Pesticides/Polychlorinated Biphenyls (PCBs), Base/Neutral/Acid Extractable Organics (BNAs), Volatile Organics (VOA), cyanide and Total Metals. All surface water and sediment samples analyzed for cyanide were found to be non- detect. Surface water samples analyzed for organics were found to be non-detect, except that methylene chloride was found at low level (2 ug/L) in two surface water samples (Cement Creek below the confluence with South Fork, and Prospect Gulch below the Galena Queen Mine) and three of the rinsate samples. One surface water sample contained a low concentration of acetone (Cement Creek at confluence with South Fork @ 3 ug/L). Three sediment samples were also found to contain low concentrations of methylene chloride (below the Gold King mine @4 ug/kg; Cement Creek below the confluence with South Fork @ 10 ug/kg; below the Mogul Mine @ 4 ug/kg). One sediment sample was found to contain low concentrations of acetone (Cement Creek below confluence with South Fork @7 ug/kg). The low concentrations of these organics are far below existing EPA standards for drinking water (methyl chloride @150 ug/L) or foods. They are not considered as potentially limiting factors to aquatic life at concentrations found. Total organic carbon was measured at low concentrations throughout the basin (<2 mg/L). During the Upper Animas synoptic characterization sampling of contaminant sources, EPA ran parallel analyses eight aqueous samples [10% of DMG's surface water samples plus samples at the four main gauging stations (A 6 8 , A72, CC48, MC34)]. They were analyzed for organic compounds, cyanide, and TOC. Eight sediment samples, collected at the same locations as the aqueous samples, were analyzed for organic compounds and cyanide. The Town of Silverton's drinking water sample was analyzed for organic compounds. Surface water samples analyzed were found to be non-detect, except that 2-Hexanone @ 8 ug/L and 1,1,2,2-Tetrachloroethane @3 ug/L was found on the mainstem of the Animas, downstream of Burrows Gulch. Trichlorethene @0.4 ug/L, Toluene @0.4 ug/L and the pesticide Dieidrin @ 0.0028 ug/L were detected in the mainstem of the Animas downstream of Burrows Gulch below the Silver Wing Mine. Toluene was found @0.4 ug/L in the waters of California Gulch, above its confluence with the Animas. Toluene was found in Cement Creek @0.2 ug/L and in Mineral Creek @0.5 ug/L above their confluence with the Animas, in the Animas river above its confluence with Cement Creek @ 0.2 ug/L, and Trichlorethene was detected at 0.6 ug/L on the mainstem of the Animas below the confluence with Mineral Creek. Regarding the analyses of sediment samples, the Silver Wing Mine had concentrations of Fluoranthene and Pyrene detected. The sediment sample collected at California Gulch above its confluence with the Animas had cyanide detected at low concentrations (0.57ug/Kg). Sediments in the Animas River above Cement Creek had Acetone @48ug/Kg, 2-butanone @3ug/Kg and Dieldrin @0.24ug/Kg present. Sediments in Cement Creek above the Animas had Acetone @230ug/Kg, Dieldrin @0.12ug/Kg, and 4,4'-DDT present @0.33ug/Kg. Acetone was also found in the sediments in the Animas River below Mineral Creek @73ug/Kg. Conclusion of Organic Analyses Concentrations of TOC were 2mg/L or below in all analyses. The low concentrations of TOC are typical for high elevation streams throughout the Rocky Mountains, particularly in streams containing high metal concentrations. There are no minimum standards set for TOC for aquatic life. TOC is assumed to have a low potential as a limiting factor, although it surely influences overall productivity of aquatic biota, Of all aqueous and sediment samples analyzed for cyanide, including at the four gauging stations that account for all surface waters in the Upper Animas, only one low level detection was found (sediments in California Gulch above its confluence with the Animas River). Cyanide has no potential as a limiting factor. A review of all analysis has led to the conclusion that organic compounds are have little or no potential as limiting factors throughout the Upper Basin to A-72. The presence of organic compounds was not investigated below A-72; however, this is also assumed to be true for the Animas Canyon because of the nearly total lack of industrialization/urbanization in that area (the exception is the narrow gauge railroad). After the Upper Animas sampling event (Farrell, 1999) EPA discontinued sampling for organic compounds and other risks to human health; presumably because their initial screening analyses indicated only minimal health risks. Inorganic Elements and Compounds (surface water) The following inorganic compounds are not considered limiting factors based on the data collected. It is generally assumed that if EPA does not have an aquatic life criteria for the element or compound that there is no potential that it is a limiting factor. 1. Antimony - Antimony occurs as a sulfide mineral (tetrahedrite) within the basin. Antimony was detected in 22% of the samples in the Mineral Creek basin and 1% of the samples in Cement Creek and Upper Animas basins. Most occurrences are at specific mine sites and not in streams. There are no adopted aquatic life criteria for antimony, however 2% of the values in Mineral Creek basin and 1% in Cement Creek and the Upper Animas exceeded the water supply criterion of 6 ug/1. 2. Arsenic - The EPA states that freshwater organisms should not be adversely affected if the 4 -day average concentration of arsenic does not exceed 190 ug/L more than once every three years and if the 1-hour average concentration does not exceed 360 ug/L more than once every three years. Mineral Creek is the only basin having sites that exceed this criteria, and none occur in the main stem of either segment 8 or 9b. Exceedances of this criteria only occur at point sources, between Red Mountain Pass and Chattanooga, and in B row ns gulch, all in segment 8 , which has no aquatic life use designation. Only in these confined areas is arsenic considered as having medium to high potential as a limiting factor. 3. Barium -Barium was found in most water samples taken in the basin at low concentrations. Three percent of the samples taken at CC48 exceed human health criteria ( 1 0 0 0 ug/l). There were no exceedances of human health criteria in either Cement Creek or Mineral Creek basins. There are no aquatic life criteria for barium. 4. Beryllium - Beryllium was detected in 8 %, 19%, and 12% of the water samples taken in Mineral Creek, Cement Creek and upper Animas basins, respectively. Less than 6 % o f all samples exceeded human health criteria ( 6 ug/l). There are no aquatic life criteria for beryllium. 5- Bismuth - Bismuth was not detected in the watershed. There are no aquatic life criteria for bismuth 6 . Boron - Seldom detected, never exceeding aquatic life criteria (LC50 @ 17-25mg/l) 7. Bromine - No aquatic life criteria for this element. 8 . Calcium - no toxicity value; associated with hardness; in the Animas watershed the more the better as hardness raises the toxic thresholds of several, but not all, metals 9. Chloride - Chloride is common in all three basins, but only one value ever exceeded water supply criteria (250 mg/1). There are no aquatic life criteria for chloride. 1 0 . .Chromium - Chromium was detected in 7%, 2 %, and 4% of the samples taken in Cement Creek, Animas, and Mineral Creek basins, respectively. No value approached aquatic life criteria exceedance 1L Cobalt -There are no EPA aquatic life criteria for cobalt. Rainbow trout have an LC 50 of 28 ug/l at a hardness of 25 mg/1. Discharging adits and springs often discharge Cobalt in the >25 to < 250 ug/l range. Only in Cement creek are there stream values for cobalt over 25 ug/l. There is no aquatic life use in this segment. Hardness tends to be quite high m Cement Creek (>100mg/l) probably negating any toxic effects of this element However, in the presence of copper, Cobalt concentrations at 50 to 250 ug/l can increase copper toxicity as much as 20%. ARSG data indicates that cobalt appears to fall out of solution rapidly upon leaving the source. Cobalt has low or no potential of directly being a limiting factor. 1 2 . Cyanide - Cyanide was detected in only one of thirty five samples analyzed, that sample was below EPA criteria for freshwater. 13. Ekoride - Detected in 99% of the samples in Cement Creek, 60% of the Animas and 76/o of Mineral Creek. There are no aquatic life criteria for fluoride. Forty five percent o f the samples exceed water supply criteria in Cement Creek basin, while 3% and 10% exceed water supply criteria in the Animas and Mineral Creek basins, respectively. 14. Gallium - No aquatic life criteria established 15. Lithium - No aquatic life criteria established 16. Nickel - Nickel toxicity is affected by water hardness. The EPA states that, except when a locally important species is very sensitive, freshwater organisms should no be adversely affected if the 4-day average concentration (ug/1) does not exceed the numerical value given by e(0-8460lIn 17. Mercury - Mercury is a human health and aquatic life concern. O f 53 samples, four were found to be above detection limits, all during the July, 1993 sampling event. Sampling location A6 8 was reported at 0.3 ug/L; CC02 measured 0.8 ug/L; MC02 and MC04 measured 0.6 ug/L, respectively. Remaining locations where mercury was detected were draining adits or natural springs. However, criterion for aquatic life is one-half the current detection limit (.2 ug/1) for total mercury, 0.2 ug/1. Total mercury was detected in 20 % of all samples in the Cement Creek basin, 10% of all samples in the Mineral Creek basin, and 7% of all samples in the upper Animas basin. Less than one percent of the samples in the main stems at A 6 8 , CC48, M34, or A72 had detectable concentrations of total mercury. Only two samples (A -6 8 @ .3 ug/1 and A-72 @ .1 ug/1) were in aquatic use class waters. Given current information, the somewhat tenuous conclusion is that mercury has low potential as a limiting factor. 18. Molybdenum - EPA has not established a water quality criterion for the protection of aquatic life for molybdenum. 19. Phosphate - There is no aquatic life criterion for phosphate. 20. Potassium - There is no aquatic life criterion for potassium. 21. Selenium - Three percent of all samples in the Cement Creek basin, 1% in the Mineral Creek basin, and less than 1% in the Animas basin had detectable concentrations of selenium. No value exceeded the aquatic life criterion. 22. Silicon - necessary element for some macroinvertebrate shells. There is no aquatic life criterion for silicon. 23. M jer - Silver toxicity is affected by water hardness. Silver generally occurs and is toxic in the msoluable form although Colorado standards are based upon dissolved Silver. For the insoluable form the EPA states that freshwater organisms should not be adversely affected if the 4-day average concentration of silver does not exceed 0.08 ug/L more than once every three years and if the 1-hour average concentration does not exceed 2 03 ug/L more than once every three years at a hardness of 100 mg/1. Twenty five percent of all samples in the Cement Creek basin had detectable concentrations (equal to or greater than 0.2 ug/1). Twenty percent of all samples in the Mineral Creek basin and 7% in the Animas basin had detectable concentrations of dissolved silver. The main stem locations A 6 8 , CC48, M34, and A72 had 3%, 3%, 0% and 9% , respectively, total recoverable silver samples that exceeded detection limits.???? 24. Sodium - There is no aquatic life criterion for sodium. 25. Sulfate - There is no aquatic life criterion for sulfate. 26. Tin - There is no aquatic life criterion for tin. 27. Titanium - There is no aquatic life criterion for titanium. 28. Vanadium - There is no aquatic life criterion for vanadium. 29. Zirconium - There is no aquatic life criterion for zirconium. 30. Njtrite+Nitratg - Nitrite is unstable in well oxygenated waters and is usually measured in conjunction with nitrate. There is no aquatic life criterion for nitrate. Nitrate values greater than 10 mg/1 exceed the water supply criterion. Nitrite+nitrate was detected in 52% of all samples in Cement Creek basin, 82% in the Animas basin, and 23% of the Mineral Creek basin. No nitrite+nitrate value exceeded the water supply criterion at A 6 8 C'C'AQ X / M / l __ A t \ r r J 3 31. Ammonia - Ammonia is toxic to aquatic life in the un-ionized form. The percentage of ammonia that is unionized is higher when the water temperature is warm and the pH is high. Neither condition exists in the Upper Animas Basin. Total ammonia was detected in 52% of all samples in the Cement Creek basin, 67% of all samples in the Animas basin, and 8 % of all samples in the Mineral Creek basin. No sample of unionized ammonia exceeded the aquatic life criterion of 0.02 mg/1 at A6 8 , CC48, M 34, or A72 The small population of Silverton results in minimal ammonia released ’to the Animas. Given the low pH and high Zn concentrations of Mineral Creek which would tend to inhibit nitrification of ammonia (Niyogi, 2000), it is a good thing that the waste water effluent from Silverton has recently been reconfigured to discharge into the Animas River, where pH is near neutral. TSS W ater samples were not analyzed for suspended solids, however, in general the geology, shallow soils, and other conditions are not conducive for high concentrations of suspended solids in the streams. Streams are relatively clear even at high flow except for the visually obvious high concentrations of iron oxides which impart a cloudy red to orange color to the water of Mineral, Cement, and the Animas in Segment 4a during storm and high flow events. Biological Parameters Predation Predation affects in community structure and function is a balance between predator and prey species and environmental factors. Left alone, barring no natural disasters, predator prey relationships fluctuate in a predictable manner. When predation exceeds recruitment, prey populations decrease and visa versa. Natural and human environmental factors can disrupt this balance. Some examples might include severe weather, introduced species, natural disaster like a volcano or disease to prey, predator or prey food base. Human induced factors include artificial food sources or extirpation of a species. The ability of species to switch prey and adapt increase the stability of the community. In some areas physical conditions dominate the community fluctuations and in others interactions with other species communities dominate the fluctuation. As with other Rocky Mountain trout fisheries, typically only brown trout reach a maturity where they will eat young fish such as trout, long nose dace and sculpin. It is not common for natural balances in trout communities to be upset by predation. There are not enough brown trout or numbers of any trout in the upper basin to suggest predation is a limiting factor. Human predation is identified as low to medium potential as a limiting factor for some fishable streams. Disease/Parasites The only disease/parasite identified as a significant factor is whorling disease, which may have been introduced into the Lower Basin in Durango. Although this disease may become a limiting factor in the future, at present it is not. Competition Although competition between and among species regularly occurs it is not known as a factor that limits composite aquatic life, although it may impact a population of a specific species. Trout species compete for prime habitat and sometimes food. Brown trout are aggressive competitors and rainbow trout are the most passive. Cutthroat trout have the most stringent habitat requirements. In areas where winter or summer habitat is limiting it is not uncommon to find all four trout species sharing the same pool. The only example of an impact from competition presently suspected is in Maggie Gulch where recently (1985) introduced brook trout may be responsible for declines in the cutthroat population. Forage Fish Forage ftsh can be an important form of food for other fish. No forage fish occur within the Upper Basin (a possible exception may be sculpin in South Mineral Creek) probably for the same reason(s) trout are not present. Forage fish do occur below Baker’s bridge and possibly in the Animas canyon. The lack of forage fish would not by itself preclude trout if other food sources were present (i.e. benthic macroinvertebrates). Bioaccumulation The accumulation of metals in trout, macroinvertebrates, and periphyton were studied in Segment 4a by Besser, 1999. Some metals were found in concentrations similar to concentrations found in other mine impacted streams. However no direct connection to toxicitv in any organism was found. ANALYSES OF PROBABLE LIMITING FACTORS There are several environmental factors that are more likely limiting aquatic life, spatially and/or temporally than the ones discussed above. It should be noted that factors dismissed in the preceding section as not being limiting may still influence these factors (e.g. Cobalt). A discussion of possible limiting factors follows: Chemical Parameters Acidity and Alkalinity fas measured hv pH units) All evidence indicate^that acidity is a primary limiting factor for most of Segments 2 , 7, 8 , and 9b. Water pH is typically at 5.0 or lower for long duration in these segments, resulting to toxicity to all species of trout. pH also influences the physical state of most metals and the ability of primary producers and many benthic macroinvertebrates to survive and function (Niyogi, 2000). Aluminum, iron, and copper have been shown to move in and out of the dissolved phase as the pH of streams increases or decreases on its journey through major source loading areas Accordingly, one can expect to find toxic conditions gaining and receding from these metals, depending upon the pH as one progresses downstream. Toxicity of metals reflects the seasonal distribution of acidic conditions as well. Although low alkalinity would not be a limiting factor in itself, its extremely limited availability particularly in Cement and Mineral creek has a profound effect on pH. Higher than normal acidity in precipitation, combined with exposed soils and rock outcrops containing disseminated iron pyrites, and a lack of alkaline buffers results in an acidic environment reflected in both surface and ground waters. Dissolved Metals This parameter has the most amount of data collected and analyzed. However, analyses information remains somewhat limited. For example, data may be lacking for the appropriate biological location, first flush events, storm events, and for specific critical stages of the life cycle for an organism. The limiting factors tables presented below are based upon dissolved (total recoverable for Fe) metal conditions at specific locations. They do not always reflect the conditions throughout the stream segment. M etals in the Solid State Iron toxicity criterion uses total recoverable iron as the unit of measurement. This is a measurement of both the solid and dissolved fractions. Direct toxicity of metal precipitates traditionally is considered minimal. Aluminum and iron precipitates have trace metals ( e.g. Cd, Cu, Zn) sorbed to their surfaces (Schemel, 1999). Little is known about their biological availability via direct contact (e.g. macroinvertebrates) or to enter the food chain. However, recently low molecular weight polymers of aluminum have been shown to be more toxic to trout than dissolved aluminum (Witters, 1998). Toxicity is reduced as the low molecular weight polymers combine to form higher molecular weight polymers. Although less toxic, higher molecular weight polymers of Aluminum can result in asphyxiation of aquatic organisms when in concentrations similar or lower than those found in Segments 4a and 9b, Total aluminum values were not evaluated as a limiting factor in the data set because this information was not known at the time and data did not always include total values. Hardness (as Calcium Carbonate equivalent^ Hardness is related toxicity thresholds for many metals. TVS and BT criteria use equations based upon hardness and metal concentrations to determine are used to determine TVS and biological thresholds. Hardness by itself is not a limiting factor anywhere sampled in the Animas watershed. Evaluations of metal toxicity is determined by the use of hardness equations throughout this report (see Chapter VI, Appendix 6 C for further explanation). Sediment Pore Water Quality Pore water quality samples, taken in the sediment bed near A72 by Nimmo et. al., 1998, indicate that this water can contain much higher concentrations of dissolved metals than the surface water column. It is possible the pore water was derived from surface water when concentrations of metal were much higher (i.e. low flow conditions). It is also possible that the pore water was coming from ground water or physical and/or chemical reactions occurring within the sediments. The relationship of sediment composition and reactivity, ground water inflows, and surface water column chemistry has not been adequately studied to determine the nature of the processes involved nor the seasonal trends in sediment pore water. Physical Parameters Fish H abitat Aquatic habitat can be affected by numerous upstream land use practices. These include but are not limited to mining, grazing, road, and in the Animas canyon, railroad maintenance. Natural processes can also affect habitat, for example channel morphology and bedload dynamics. The quantity and quality of available habitat may be a limiting factor. Spawning, rearing and adult habitats for trout were evaluated based upon the information provided in the Fisheries Report (Chapter VI, Appendix 6 A). Macroinvertebrate Habitat Conditions necessary for successful benthic macroinvertebrate populations are less understood and quite variable due to the large number of trophic levels and diversity of taxa available. Segment 4a was investigated for available habitat for macroinvertebrates. Walsh (1999) found habitat to be quite adequate throughout the segment. Minimal embeddedness existed and the boulder/cobble substrate of this steep gradient stream provided adequate habitat. Anderson found interstitual spaces were adequate in spite of flocculate accumulations. Precipitate Accumulations The accumulation of precipitates on stream sediments has been shown to be a detriment to many but not all, macroinvertebrates (Chapter VI- Precipitates as Macroinvertebrate Stressors). It is considered as a potential limiting factor for fish spawning beds and macroinvertebrate habitat where accumulations are heavy and regular. Biological Parameters Potentials for biological limiting factors are mostly based upon the Fisheries and Macroinvertebrate Reports in Chapter VI. This analysis is unable to evaluate factors that might be limiting algae, fungi, and other life forms due to the lack time, funding, and knowledge of life cycle requirements. Predation was dismissed as non-limiting earlier in this chapter except for human predation. Fish populations, while recently increasing in the Animas near Elk Park and Howardsville (Segments 4a and 3a respectively), are now under increased fishing pressure from the public. This must be considered, especially when analyzing future monitoring results. SEGMENT BY SEGMENT ANALYSES OF POTENTIALLY LIMITING FACTORS Segment 2 (Animas River Above Minnie Gulch) Aquatic Species Present Trout not present with the exception of short stretch (<100 yds) of the North Fork of the Animas at Denver Lake. Macroinvertebrates only sampled at A33, lowest point of Segment 2. Location of Determination of Chemical Parameters Station A33 - Animas River above South Fork Limiting Factors Table Organism Parameter Compound Taxa Potential as a Limiting Factor Or Condition None Low Medium High Fish Physical Spawning Brook X Habitat Brown X Rainbow X Rearing B rook X Habitat Brown X Rainbow X Adult B rook X H abitat B row n X Rainbow X Chem ical PH Brook X B row n X Rainbow X Aluminum Brook X Brow n X Rainbow X Cadm ium B rook X Brow n X Rainbow X Copper B rook X B row n X Rainbow X Iron B rook X B row n X Rainbow X Lead B rook X B row n X Rainbow X M anganese B rook X Brow n X Rainbow X Zinc B rook X B row n X Rainbow X Biological Food All trout X Predation A ll trout X M acroinve Physical Interstitual All X X @ rtebrates Space1 Burrow s & Calif. Chem ical PH All X Al, Cd, Cu, Fe, Mn, Pb, Z n Biological Food All | Variable-trophic level specifi c Sum m ary There is much variability within this segment. The headwaters, particularly in the North and West Forks of the Animas, have high concentrations of most metals, low pH, and severe habitat degradation from accumulated flocculates, mostly of aluminum oxides. (These areas contain quartz-sericite-pyrite alterations). Metal concentrations, pH, and habitat degradation from accumulated metal oxides have a high potential as being limiting factors. The limiting factors table provided above was based upon data and conditions at A33, just above Eureka. Most tributaries and the Animas River below Grouse Gulch have improved good water quality. The steep gradient and dilution provided by relatively clean tributaries results in aluminum having only a moderate potential as a limiting factor. Zinc, cadmium, and copper concentrations have high potential as limiting factors. Food sources for fish would have a moderate potential as a limiting factor due to minimal aquatic insect availability. Segment 3a (Animas River between Silverton and Minnie Gulch) Aquatic Species Present A sustainable Brook trout fishery exists above Howardsville. Occasional rainbow and cutthroat trout have been recorded. Fishery below Howardsville appears to be healthy but recruitment likely to come from Howardsville to Maggie gulch area which has both instream and side stream reproduction. Aquatic macroinvertebrate populations have abundant diversity and density, but severely reduced in both these parameters below Arrastra Creek confluence. Location of Determination of Chemical Parameters Station A 6 8 above the confluence of the Animas with Cement Creek. O rg an ism P a ra m e te r C o m p o u n d T axa Potential as a Limiting Factor O r C o n d itio n None Low Medium H ig h Fish Physical Spawning B rook X Habitat B row n X Rainbow X R earing Brook X H abitat Brow n X Rainbow X Adult B rook X Habitat Brown X Rainbow X Chem ical pH B rook X B row n X Rainbow X A lum inum B rook X Brown X Rainbow X Cadm ium B rook X to X B row n X Rainbow X Copper Brook X to X Brow n X Rainbow X Iron B rook X Brow n X Rainbow Xto X Lead B rook X Brown X Rainbow X M anganese B rook X to X Brow n X to X Rainbow Xto X Zinc B rook X Brow n X Rainbow X Biological Food All trout X Predation 1. H um an All trout X 2. O ther All trout X M acroinve Physical Interstitual All X rtebrates Space2 Chem ical .PH All X Al, Cd, Little known of metal in fluences Cu, Fe, other than moderate tc> high M n, Pb, probability as limiting fac to r for Zn som e taxa (e.c. B a etis) Biological Food All Variable; trophic level specific Sum m ary Cadmium, Manganese, and Zinc have high potential of being LF to trout and most macroinvertebrates . The self sustaining population of brook trout in the upper stream segment indicates that although BT and TVS are often exceeded life is sustained. A healthy community of macroinvertebrates occurs above the Howardsville bridge, but this rapidly declines near Boulder Gulch (Chapter VI, Appendix B). Fish data suggests a decline in a downstream manner as well. Copper has moderate potential of being a limiting factor for brook trout, which are more sensitive to this element. The source of these metals are presently still undifferentiated although the large Mayflower Mill tailings ponds are in this vicinity. The relatively healthy populations of aquatic insects at and above Howardsville (A53), where metal concentrations are known to be lower than from Boulder Creek downstream (A60 and A6 8 ), indicates that these same elements may effectively limit their populations. Physical habitat has medium potential as a factor limiting for brown trout. The stream segment is within normal brown trout range, although it approaches its upper elevation limits. Observed flocculates are likely limiting to some aquatic insects at the Howardsville bridge and from near Boulder creek downstream (Boulder Creek is not the source of the flocculates however). Cadmium, manganese, and zinc thresholds are exceeded on a regular basis, however the brook trout are somehow able to survive. Table 8.2b (i) from Chapter VIII is inserted here to give the reader additional information for what might be responsible. Table 8.2b(i) Comparison of ambient quality to TVS and adopted water quality are m micrograms per liter except pH (s.u.) and hardness (m e/\) Hard pH AI Cd Cu Fe " Fe ' Pb XST ------z n “ tree Dis TVSn/r.c 6.5„ „ 87 1.1 - Ï0...... tOOCf - 2.9 1700 130 » ti 87 1.7 11 194 132 3 1000 540 A53 97- 99 7,0 83 2.1 4 86 54 Bdl 262 304 A60 ‘97-‘99 6.6 150 2.4 5 - Bdl Bdl 214 111 ------99i-, i, » , 115 6.2 115 3.0 9 227 120 ____dui Bdl zjuu 2500 yuu 900 Bdl=Below detection limits. The Animas River is degraded by an unknown but significant source of dissolved metals entering below A60. There is a 2 to nearly 4 fold increase in the zinc load that enters the Animas River between A60 and A6 8 . During April and May 1999 the zinc load from the A60 to A 6 8 reach averaged about 40 percent of the zinc load at A72. TVS are only being exceeded for cadmium and zinc at A53 and A60 and then not by much. The zinc biological threshold for brook trout is not exceeded at A53 or A60 but is being exceeded at A 6 8 . Acute cadmium exceedances are low in frequency (Figure 70, Biotoxicity Report) and occur in the spring. Either the trout are able to avoid these conditions, have become adapted, or the water temperature being low at that time of year results in less than toxic conditions. During biotoxicity experiments with trout in the Animas basin, Pat Davies (1999) recorded unusual tolerance to high copper concentrations among trout when the water temperature was near zero Celsius. This might be true for cadmium as well. Regardless, young of year and a good distribution of size classes in brook trout near A53 indicates this is a good fishery. Trout sampling was not undertaken at A6 8 but this author has witnessed several Silverton children catching mature adult brook trout at this location. These probably drift in from above. Segment 3b (Animas River between Cement and Mineral Creek) Aquatic Species Present Trout have not been thought to exist in this segment due to the heavy precipitation of metals as the neutral water of the Animas mixes with the metals laden, low pH water of Cement Creek. DOW electoshocking in 1998 demonstrated brook trout are present only in the clean water plume of the Upper Animas before mixing with Cement Creek waters. Location of Determination of Chemical Parameters No water samples have been entered into the ARSG database for this short segment. USGS tracer studies conducted in 1998 will have results available following publication. Sum mary What is known about this segment is that the neutral waters of the Animas mix with the acidic waters of Cement Creek resulting in the rapid precipitation of iron and aluminum oxides with other metals sorbed to their surfaces. The streambed is heavily impacted by flocculate accumulations. Habitats for macroinvertebrates would be severely limiting. Some assumptions can be made as to chemical limiting factors. Cadmium, manganese, and zinc concentrations have high potential as limiting factors since they are limiting factors immediately above this segment, plus they would not change their physical state. Copper would probably remain as highly limiting while total recoverable iron concentrations would have a low to moderate limiting potential. Segment 7 (Cement Creek basin) Aquatic Species Present No fish in basin. No benthic macroinvertebrates in mainstem. Some macroinvertebrates in tributaries (see Chapter VI, Appendix VI-C). Location of Determination of Chemical Parameters Station CC48, approximately 1/4 mile above the confluence with the Animas River. O rg an ism P a ra m e te r C o m p o u n d T ax a Potential as a Limiting Factor O r C o n d itio n N one L ow M ed iu m H igh Fish Physical Spawning B rook X H abitat B row n X Rainbow X R earing B rook X H abitat B row n X Rainbow X Adult B rook X H abitat B row n X Rainbow X Chem ical pH B rook X Brow n X Rainbow X Aluminum Brook X B row n X Rainbow X Cadmium Brook X to X Brow n X Rainbow X C opper B rook X to X B row n X Rainbow X Iron Brook X Brow n X Rainbow X Lead B rook X B row n X R ainbow X Manganese Brook X Brow n X Rainbow X Zinc B rook X B row n X Rainbow X Biological Food All trout X Predation All trout X M acroinve Physical Interstitual All X rtebrates Space3 Flocculates Stoneflie X S M ayflies X Caddis X Chem ical pH All X Al, Cd, Cu, All N o t inc ividually analyzed because Fe, Mn, Pb, all metal concentrations are so high. Zn High Potential for most species X Biological Food All Variable-trophic level specific Sum m ary Most of this segment is totally devoid of aquatic life. Biological thresholds for the seven metals listed in the above table are regularly and nearly continuously exceeded. In addition, dissolved Silver TVS is exceeded 8 % of the time. If mining sources were eliminated aluminum and iron concentrations would still limit aquatic life. Habitat for trout and aquatic insects is also a limiting factor due to filling of interstitial spaces, and a hard armoring of aluminum and iron hydroxides substrates. Since most of this arises from natural sources, even total mine site remediation will likely not result in aquatic biota habitability. Segment 8 (Mineral Creek above South Fork of Mineral Creek) Aquatic Species Present Few benthic macroinvertebrates, no fish. Limiting Factors Summary (See segment 9b for complete analysis of downstream area). Limiting Factors Table Organism Parameter Compoun Taxa Potential as a Limiting Factor d Or None Low Medium High Condition Fish Physical Spawning B rook X H abitat Brow n X R ainbow X R earing B rook X H abitat B row n X Rainbow X A dult B rook X H abitat B row n X Rainbow X Chem ical pH B rook X B row n X R ainbow X IX -22 A lum inum B rook X Brow n X R ainbow X Cadmium Brook X Brow n X Rainbow X C opper B rook X B row n X Rainbow X Iron B rook X Brow n X R ainbow X Lead B rook X Brow n X Rainbow X Manganese Brook X Brow n X Rainbow X Zinc B rook X B row n X Rainbow X Biological Food All trout X Predation All trout X M acroinve Physical Interstitual All N ot stu died bu t presumab ly high rtebrates Space4 potentia as limit ng Flocculates Stoneflies X M ayflies X Caddis X Chem ical pH All X Al, Cd, X Cu, Fe, Zn Biological Food All Variable-trophic level specific Sum m ary This segment is quite similar to Cement Creek, Segment 7, with high potential limiting factors tor aluminum, cadmium, copper, zinc and pH. One of three samples analyzed for Ag exceeded aquatic life criteria. Not enough Ag data to draw conclusion. Unlike Cement Creek, manganese is not a limiting factor. Aluminum and iron loading results in severe degradation for both trout and macromvertebrate habitat. Even if pH were raised through remediation these metals would contribute to continued habitat degradation by smothering the substrate unless removed. A quatic Species Present Fish not present. Limited benethic marcroinvertebrate diversity and densities. Location of Determination of Chemical Parameters USGS Gauging Station MC34 approximately 1/4 mile above the confluence with the upper Animas River. Limiting Factors Table Organism Parameter Compound Taxa Potential as a Limiting Factor Or Condition None Low Medium High Fish Physical Spawning B rook Not specifically evaluated H abitat Brow n but substrates covered with R ainbow seasonal heavy flocculates. R earing B rook H abitat Brow n Low to Med. Potential Rainbow A dult B rook H abitat B row n Rainbow Chem ical pH B rook X Brow n X Rainbow X A lum inum B rook X B row n X R ainbow X Cadm ium B rook X to X B row n X to X Rainbow X to X Copper B rook X to X B row n X Rainbow X to X Iron B rook X B row n X R ainbow X Lead B rook X B row n X R ainbow X M anganese B rook X 1 B row n X Rainbow X* Zinc B rook X B row n X Rainbow X Biological Food All trout X to X Predation 1. Hum an All trout X 2. O ther AH trout X M acroinve Physical Interstitual All X to X rtebrates Space6 Chem ical pH All X Al, Cd, Seasona low p t and high Al, Cu, and C u, Fe, Zn Fe e:iceedam ;es limits most m acroin vertebral es, reduces primary producti vity. Biological Food All Variable-trophic level specific Sum m ary Aluminum, Cadmium, Copper, Iron, and pH have high potentials as limiting factors. Zinc does not exceed biological thresholds for brook trout but exceeds those of rainbow and brown trout. Besides severe aluminum and iron toxicity, precipitates from these metals appears to result in severe habitat degradation for both trout and macroinvertebrates. This condition has not been adequately studied however. Remediation that resulting in elevating pH would increase habitat degradation from precipitation of natural loads of iron and aluminum unless these were removed as well. Low flow conditions are severally toxic due to high concentrations of the metals. Segment 4a Aquatic Species Present Brook trout present only near Elk Park (lower 4a). Macroinvertebrate minimal in taxa (4) and diversity at A72 but improves substantially near Elk Park. Location of Determination of Chemical Parameters USGS gauging station at A72, approximately 1 mile below the confluence of Mineral Creek. O rg an ism P a ra m e te r C o m p o u n T ax a Potential as a Limiting Factor d O r N one Low M ed iu m H igh C o n d itio n Fish Physical Spawning B rook X H abitat B row n X 5 No aquatic ci term; below TV s 6 Visual observations only (substrate heavily an nored most loca ions) Rainbow X R earing B rook X H abitat Brow n X Rainbow X Adult B rook X H abitat Brow n X Rainbow X Chem ical pH All trout X to X A lum inum B rook X B row n X Rainbow X Cadm ium B rook X to X Brow n X to X Rainbow X to X C opper B rook X to X B row n X Rainbow Xto X Iron B rook X B row n X Rainbow X Lead Brook X B row n X Rainbow X M anganese B rook X Brow n X R ainbow X Zinc B rook X Brow n X R ainbow X Biological Food All trout X Predation 1. H um an All trout X X at A-72 E lk P. 2. O ther All trout X M acroinve Physical Interstitual Ail X to X rtebrates Space7 Chemical pH Ail Low to medium taxa & season dependent) Al, Cd, High limiting for most taxa. Cu, Fe, C addis sp. (metals tolerant sp.) okay M n, Zn Biological Food Ail Variable-trophic level specific Iron, aluminum, and pH exceedances are most severe during the low flow months of winter. Manganese follows this trend. Zinc does not exceed biological thresholds for brook trout but has high potential to limit other trout. Copper and cadmium have moderate potentials as limiting factors. Trout habitat has been assessed as being adequate to sustain moderate populations (Cady et al 1996; Standard Metals Corp., 1985; Cadmus Group, 1994). However, the area below the confluence of the Animas River with Cement and Mineral Creeks is a mixing area of the high pH water (Animas) with low pH water with high aluminum and iron concentrations (Cement, Mineral), This results in precipitation of large amounts of these metals that accumulate as flocculates on the streambed. Raising the pH in this mixing area induces precipitation of metal oxides that result in flocculates that reduce macroinvertebrate habitat availability, particularly for some taxa. Nevertheless, Walsh (1999) found habitat to be adequate throughout the segment (following a high flow event). Minimal embeddedness existed and the boulder/cobble substrate of this steep gradient stream provided adequate habitat. Later in the year, Anderson found that interstitual spaces were adequate in spite of flocculate accumulations. Downstream from A72, at A73, fish are able to survive indicating improved chemical and physical conditions exist. Stream substrates appear cleaner for much of the year. Few water quality samples have been taken from this area due to its remoteness, but data suggests that the increase in aquatic life in a downstream fashion is reflective of both improved habitat and water quality. The primary chemical change observed is a reduction in the dissolved concentration of aluminum, presumably as it continues to precipitate as an oxide. Cadmium and zinc remain dissolved, their concentrations being lowered by dilution. Segment 4b Aquatic Species Present Upper portion of this segment contains only brook trout. Proceeding downstream, brown, rainbow and cutthroat gradually become established near Cascade Creek. Recruitment likely from tributaries. Native fish (suckers, minnows, sculpin) supplement a similarly diverse trout population in the Animas between Baker's bridge and Durango. Proceeding downstream from Elk Park, macroinvertebrate populations slowly increase in diversity while densities remain low until Baker’s bridge. From there south, densities increase but diversity remains fairly constant. Location of Determination of Chemical Parameters Station A75 below Baker's Bridge Organism Parameter Compound Taxa Potential as a Limiting Factor Or Condition None Low Mediu High m Fish Physical Spawning Brook X Habitat Brown X Rainbow X Rearing Brook X Habitat Brown X Rainbow X Adult Brook X Habitat Brown X Rainbow X Chemical pH All trout X Based Aluminum Brook ? upon data Brown ? from Rainbow ? Baker's Cadmium Brook X bridge Brown X only Rainbow X Copper Brook X Brown X Rainbow X Iron Brook Xto X Brown Xto X Rainbow Xto X Lead Brook X Brown X Rainbow X Manganese Brook X Brown X Rainbow X Zinc Brook X Brown X Rainbow X Biological Food All trout X 1, Human All trout X 2. Other All trout X Macroinve Physical Interstitual All X rtebrates Space8 Chemical pH All X 8 Visual obsenations only (substrate heavily armjred most loca ions) Al, Cd, Cu, X Fe, Mn, Pb, Zn Biological Food All X Variable-trop lie level specific Summary Zinc concentrations have high potential for limiting rainbow trout and low potential for limiting brown trout. Copper, cadmium, and iron have low potentials for limiting all trout species. No other factors considered appeared to limit aquatic biota. The segment is reflective of biodiverse, high elevation, and steep gradient streams found throughout much of the Rocky Mountains. Minimal data from within the Animas canyon suggests the upper reaches of this segment are still impacted by aluminum, iron, and zinc. Proceeding downstream these elevated concentrations are diluted until they have low potential as limiting except for rainbow trout. SUMMARY OF LIMITING FACTORS ANALYSES The reduction of each factor with a high or moderate potential as limiting aquatic life is most desirable. Identification of the sources of these factors was shown in Chapter VIII. The potentials for remediation are provided in Chapters X and XI. Chapter XII provides recommendations for stream standards that are reflective of potential reductions. BIOLOGICAL POTENTIALS IF IDENTIFIABLE MINING IMPACTS WERE NOT PRESENT Regulatory emphasis of the Clean Water Act is placed on what uses are attainable. Impacts from historic mining cannot be entirely remedied regardless of cost and resources available. However, the Act does require that swimable and fishable uses must be attained unless it can be demonstrated that the limiting condition is human induced but irreversible or that the limiting condition is from natural causes. This section takes a look at what the condition of the stream segments that are under current scrutiny might be like if identifiable mining related detriments to water quality were removed in entirety. What would the metal concentrations be and what species of aquatic life might be expected? Little is known of the needs, and even less of the ecological function, necessities, toxic thresholds of macroinvertebrates in this high elevation watershed. Fortunately, we do have a pretty good information on the thresholds for toxicity of trout species. Here, they are used as the primary indicators of the potential for biological diversity since they can only be sustained if a diverse and sustainable population of primary producers and benthic macroinvertebrate exists as well. Since TVS are generally nearly as protective as the biological thresholds Chapter VI - Appendix C), and because sustainable populations of brook trout already exist in the impaired Segment 3a, these widely accepted criteria are used to help determine the biological potential if mining impacts did not exits. For more specific comparisons of TVS to biological threshold criteria refer to Table 9.1. Table 9.1 Comparison of the protectiveness of Table Value Standards in Animas stream segments to Biological Thresholds (TVS) for 3 species of trout. (For metals that have high potential as Limiting Factors) ______METAL Most Protective Criteria 3a i a 4b 9b Chronic Acute Chronic Acute Chronic Acute Chronic Acute A1 TVS* TVS=BT TVS* TVS=BT TVS* TVS=BT TVS* TVS=BT Cd TVS over- BT (TVS TVS=BT BT (TVS TVS (probably TVS (probably TVS over- BT (TVS protects B; doesn't protect) doesn’t protect) over-protective slightly over- protects B; doesn't protect) BT=TVS for all sp.) Protective all under protects L,R sp. L,R_ Cu TVS TVS TVS=BT TVS TVS TVS BT for B,L TVS over- TVS = BT for protects all sp. R Fe TVS = BT TVS = BT TVS = BT TVS =BT TVS = BT TVS =BT TVS = BT TVS = BT (except for R, (except for R, (except for R, (except for R, thenBT) thenBT) then BT) thenBT) Mn BT BT BT BT No No No No Exceedances Exceedances Exceedances Exceedances Zn TVS over No B criteria TVS over- No B criteria TVS over No B criteria TVS over No B criteria protects B, TVS approx.= protects B, TVS over- protects B,L; BT=TVS for protects B; TVS for R under-protects BT uniter for L, R protects L,R BT for R L,R TVS=BT forL while over L,R. (use BT) (useBT) (use BT) (useBT) (use BT) BT for R protects L (useBT) (useBT) ♦TVS TVS has no variable for pH while BT does. Chronic criteria for BT and TVS is set at 87 ug/I for all pH ranges for brown and brook trout but for rainbow trout BT is 750 ug^l when pH >7.0. Below pH 7.0 the criteria is 87ug/l. For simplicity, we have used Table Value Standards, graphed alongside probable concentrations, as determined through the regression model outlined in Chapter VIII, for each metal if all identifiable mining impacts were removed. Stream metal concentrations have been assigned to four possible sources (Figures 8.18 - 8.21). They are groundwater, undifferentiated surface runoff (which includes other human induced sources and natural geological processes), mine wastes, and adits. The sum of mine waste and adit contributions is considered identifiable mining impacts. As described in Chapter VIII, a component of the ground water may contain impacts from mining. With the exception of the Animas between Eureka and the A72 stream gauge, this component is considered to be minimal. The groundwater of this area has unusually high metal loads and although the area contains numerous tailings impoundments, exact sources have yet been determined. For the other sub-basins this treatise assumes that other impacts from mines on the groundwater condition are offset by the assumption that adit discharge loads are completely a result of mine impacts. It has been shown that many springs and seeps of tributaries with little or no mining are major contributors of metal loads, particularly iron and aluminum (Wright, 1995). Mines intersect fractures and faults that may feed many of these springs and seeps. After intersecting these water bearing structures, the water takes a path of least resistance which is usually down a drift to exit as an adit discharge. Of necessity, these adit discharges have been calculated as being due to mine impacts even though a significant but unknown portion of the loading had already been in the ground water and that would have been attributed to the ground water condition. Due to our present inability to measure these minor components accurately, our present assumption is that the ground water load portion of the adit discharges are offset by the mine related impacts of the ground water. As seen below pH is not currently a limiting factor for segment 3a so it is reasonable to assume it would not be if mining impacts were removed. In Cement and Mineral Creeks, where the geochemical processes are arguably dominated by the natural oxidation of iron, which is the source of most hydrogen ions, it may be possible to estimate the potential reduction of hydrogen ions if mine impacts did not exist. Time and resources did not allow this UAA to accomplish this task. It is known that many springs and seeps, and at least one major tributary in Mineral Creek (the Red Trib) unimpacted by mining, have a pH of approximately 3.5. Also immediately below the American Tunnel treatment plant on Cement Creek, the pH in the creek is above neutral due to the treated discharge. In spite of only minimal mining impacts below this discharge point, the pH of Cement Creek retains its normal pH range of 3.5 to 4,0! These areas of low pH contributions have recently been attributed to the extensive Quartz-Sericite-Pyrite and Acid Sulfate alterations within Cement and Mineral Creeks (Fig 7.1). Removing mine impacts would not affect these contributors of acidity. Considering the pH is a logarithmic scale where each standard unit is 10 times more acidic that the next higher unit, it is difficult to rationalize that the pH would increase beyond a unit. Trout need a pH greater than 6.0 to survive. The following analyses are for impaired segments that had standards disapproved by the EPA. Although Cement Creek has approved ambient standards in place it has been included for comparison. Predicting ecosystem function, taxa, and biomass is not possible but the following text is provided using professional judgement based upon conditions tolerated by aquatic life in various stream segments within the Animas watershed. SEGMENT 3A_- ANIMAS RIVER ABOVE SILVERTON This segment has no acid sulfate or quartz-sericite-pyrite alterations so it is not surprising that aluminum and iron concentrations are minimal with or without the mine impact component. Without known mining impacts, there would be no exceedances of TVS for aluminum, cadmium, copper, and iron (Figure 9.2a). Manganese would only slightly exceed chronic TVS for the months of March and April. However, dissolved zinc would still exceed both chronic and acute standards for all months of the year (Figure 9.2b). The resulting biological potential would certainly be improved; however, diverse aquatic life, including sensitive species (e.g. mayflies, brook trout) already exists. Brook trout have either adapted to the existing high zinc concentrations or are able to find reiuge during sensitive life stages, or both. Conditions would remain toxic for brown, rainbow and cutthroat at A68. There are presently few iron and aluminum precipitates but if mining impacts were removed, the minor limitations flocculates pose near Howardsville and Boulder Creek would be removed. This evaluation was performed with data collected at site A68. It has recently been shown that this location differs significantly, having higher concentrations of nearly all metals, than for the Animas River above Howardsville. Between Arrastra Creek and A68 there is a large increase of metal loading from undetermined sources (Chapter VIII, and Paschke et. al, 1998). If these sources were attributable to mining impacts the non-mining loads would be correspondingly less, resulting in higher biological potentials. Figure 9.2b indicates that zinc concentrations would greatly exceed TVS in the early spring. Half of this relatively low elevation valley faces south, resulting in early runoff conditions that might account for this high flush of metals. Further evaluations are needed to locate the sources of loading to ground water. Existing tailings ponds may or may not be those sources. Non-Mining Cone. —El— Chronic T V S —A—Acute TVS Cu <§A68 •Non-Mining —Q— Chronic TVS Acute TVS Figure 9.2b Comparison of Segment 3a (Animas) Non-Mining Concentrations to Table Value StandardsZn. Mn forand Value Table to Concentrations Non-Mining (Animas) 3a 9.2b Figure Segment of Comparison R -35 This is the only stream segment being analyzed with approved use classifications and standards. It is recognized that concentrations of metals, plus low pH, are so high from irreversible sources that ambient standards have been adopted. Segments 2 and 9a are similar in this regard and have similar geothermal alteration areas that are responsible for much of the loading. High aluminum and iron concentrations, with correspondingly low pH's, are normal for these streams. If the mine impact components are removed from Cement Creek, aluminum and iron would still exceed TVS for all months of the year (Figure 9.3a). Cadmium and Manganese would no longer exceed TVS, while zinc would remain in exceedance of both chronic and acute TVS for all months of the year. Due to the high concentrations of iron and aluminum, and low pH, aquatic life would be limited to a few acid tolerant species of macroinvertebrates. As pH increased, an increase in precipitation of these metals would be expected to severely limit aquatic life habitat, including that of macroinvertebrates. Nevertheless, a few taxa (e.g. Caddis and Stoneflies) that have adapted to these conditions in other locations could be expected. Additional algae and fungi taxa might be expected as well, but stresses from dissolved zinc, metal precipitates, and low pH woutd limit their productivity. Although brook trout in Segment 3a have demonstrated their ability to withstand similar zinc concentrations, for whatever reason, no fish would be expected to survive the stresses of a minimal food supply, an expected pH below 5.5, armored habitats, and the toxic effects of aluminum and iron. Similar consequences would be expected in Segment 9a and in Segment 2, above Animas Forks, where low pH, aluminum, and/or iron precipitates prevail. ■ Non-MiningChronic Cone. TVS ■ —C3— Cu @CC48 Non-Mining Cone. —O— ChronicTVS —A —AcuteTVS 0.00 100.00 40.00 . . 80.00 o § 60.00 o. a 20.00 % IX -37 D JFMAMJ JASON JFMAMJ 0 500 1000 3500 3000 ■■■■<► • Non-Mining Cone. Chronic TVS —Qh— ■■■■<► —AAcute — TVS ______1500 u 2500 o 2000 £ s i IX -38 This short segment presently has few mining impacts from sources within its area. As in all evaluations the mining impacts from all known sources upstream of the point of reference (MC34) has been removed (Figures 9.4a & 9.4b). Mineral Creek geology contains large areas of Quartz-Sericite-Pyrite and Acid Sulfate alterations (Figure 7.1). If mining impacts are removed from consideration, these areas will dominate the loading of metals and determine the pH in the water at Segment 9b. The figures demonstrate that most of the cadmium, copper, and manganese would not exceed TVS. Comparing this to Figure 8.9 one realizes that mining impacts contribute heavily to the loads of these metals. Zinc would only exceed chronic and acute TVS during the high flow months of April, May, and June, and then by a relatively small amount. Iron and Aluminum concentrations are considerably lower after mine related impacts are removed. However, both metals will continue to exceed TVS. Iron would exceed TVS during the low flow months and November, December, and January. Aluminum would exceed chronic TVS for all months except June, September, and October. Aluminum would exceed acute TVS for December through March. (See Chapter XI for a discussion of the potential that many of the adits responsible for much of the iron loading may be "irreversible"). Without impacts from mining the water quality of Mineral Creek would be greatly improved and result in increased aquatic biomass and diversity. Zinc, cadmium, and manganese levels would not exceed biological thresholds for brown or brook trout, and rainbows and cutthroat thresholds are not exceeded by much. Brook trout survival would likely be impaired by copper as TVS are not protective enough for this species. Unfortunately these potentials are overcome by the toxicity of aluminum. Aluminum would be the primary limiting factor for the segment. The pH for this segment is much harder to ascertain. With mine impacts the pH gets extremely low during the low flow period, Removing those impacts would raise pH but would also result in an increased amount of aluminum precipitates, which would decrease habitat for food sources and trout. It is unknown if pH would rise above the 6.0 threshold required by trout. Trout migration through the segment in late spring through fall would likely be possible. Some taxa of macroinvertebrates already exist in this segment. With no mine impacts the diversity would likely increase. As Niyogi results suggest, stress from aluminum precipitates would likely keep macroinvertebrate and primary producer productivity and function at a minimum. • Non-Mining Conc. —O— Chronic TVS —A —Acute TVS Cu @ MC 34 50.00 . ; 40.00 ... . Hr^ ■ g 30.00 • \ •j/p;:p -lE IB 8 20.00 r y * ~ j a r r * K g - 1 0 .0 0 . . É 0.00 - . . »-^rTT ' 4 ~ i % r fsM •Off N D -■1Q.0Æ —♦ — Non-Mining Cone. —O— Chronic T V S —A — Acute TVS Figure 9.4b Comparison of Segment 9a (Mineral Cr) Non-Mining Concentrations to Table Value Standards for Mn and Zn. SEGMENT 4A - ANIMAS RIVER BELOW SILVERTON This segment has been evaluated from data gathered at A72, near the upper end of the segment. Due to the inflows of high concentrations of iron and aluminum attributed to the non-mine related components of Mineral and Cement Creeks, the segment would likely still function as a mixing area where precipitates would be falling from solution forming flocculates that cover stream bed sediments. Cadmium, and manganese would no longer be limiting factors. Copper would only slightly exceed chronic TVS during May and June, However, zinc and iron concentrations would remain above both chronic and acute TVS for all months of the year. It is difficult to predict aluminum exceedances. If pH did not change, aluminum would exceed chronic TVS for most months of the year; at approximately twice the acceptable level. Depending upon the amount of hydrogen ions attributed to mine impact oxidation of pyrite, pH might substantially be raised, resulting in reducing the dissolved aluminum component below exceedances. (Methods of quantifying pH changes will be explored in the Chapter XI). Aluminum oxides might remain a problem. Whereas pH alone is currently a limiting factor, it likely would not be without mine impacts. Figure 8.11, depicting existing conditions at A68, is nearly identical for metals other than aluminum and iron when compared to Figures 9.5a and b for the non-mining component at A72. Without mining impacts, water quality would allow for a diverse ecosystem, if it were not for high aluminum and iron concentrations. If aluminum and iron are excluded momentarily, one would expect the biological potential would closely reflect what aquatic life presently exists at A68. Trout, and possibly sculpin, would be expected to inhabit more of the segment (trout are limited to the furthest downstream portion currently). IX -43 IX- 4 4 Unfortunately iron and aluminum coming from Cement and Mineral Creeks alteration areas excludes this possibility. The area below the confluence of these streams would still be a mixing area of neutral and low pH waters that would result in precipitation of aluminum and iron oxides. These would serve to reduce the biological potential of primary producers and macroinvertebrates as well as exceed the biological thresholds of numerous taxa. Although we have limited data, it appears that iron and aluminum concentrations at A73 (Elk Park) are much closer to those expected at A72 with the mining impacts removed. This is currently a limiting brook trout fishery. Macroinvertebrate diversity gradually increases in a downstream direction from A72. For these reasons it is reasonable to conclude that the biological potential at A72 would closely resemble current aquatic life conditions at A73. SEGMENT 4B - ANIMAS BETWEEN ELK PARK AND JUNCTION CREEK Too few samples have been taken within the Animas canyon to complete this type of analysis. Although numerous samples exist from A75 at Baker's bridge, a regression model was not deemed necessary. Table value standards are nearly being met for aquatic life at A75. Only zinc slightly exceeds TVS. It's reasonable to assume that zinc would not exceed TVS if mining impacts did not exist in the Upper Animas. Aquatic life is already quite diverse in this segment, particularly below Cascade Creek. The existing aquatic ecosystem, in function, taxa diversity* and productivity currently existing below Cascade Creek would likely occupy much of the segment above Cascade Creek. Potential limiting factors near Elk Creek would be impacts from iron and aluminum precipitates and possibly zinc concentrations thresholds for some sensitive species (e.g. cutthroat and rainbow trout, some mayflies sp.). REFERENCES Besser, John M., Brumbaugh, William, Church, S.E., and Kimball, B.A., 1998. Metal Uptake, Transfer, and Hazards in the Stream Food Web of the Upper Animas River Watershed, Colorado, U.S.G.S. Open File Report 98-297, p. 20. Besser, John M., Nimmo, Del Wayne R., Milhous, Robert, and Simon, William. 1998, Impacts of Abandoned Mine Lands on Stream Ecosystems of the Upper Animas River Watershed, Colorado. U.S.G.S. Open File Report 98-297, p. 15. Besser, John M., and Leib, Kenneth J,, 1999. Modeling Frequency of Occurrence of Toxic Concentrations of Zinc and Copper in the Upper Animas River. Proceedings of the Technical Meeting, Charleston, South Carolina, March, 1999, p 75-81. Cadmus Group, 1994. Written Rebuttal Testimony. State of Colorado's designated use classifications for Proposed Segments 3a, 3b, 4a, 4b, and 9b in the Upper Animas River and Mineral Creek; Evaluation and proposed alternatives to the State's recommendations. Prepared for the Sunnyside Gold Corporation, Silverton, CO. Cady, T,, Horn, B., Owen, Simon, B., Stover, B., 1996. Reconnaissance of the Animas Canyon (August 16-18,1995). Church, S.E., Kimball, B.Z., Fey, D.L., Ferderter, D.A., Yager, T.J., and Vaughn, R.B., 1997. Source, transport and partitioning of metals between water, colloids, and bed sediments of the Animas River. Colorado: U.S. Geological Survey Open-File Report 97 -151, 135 p. Clements, William H., 1999. Upper Animas River Biological Evaluation Draft Final Report, prepared for San Juan/Rio Grande National Forest, U.S.D.A. Forest Service. Completion date unknown. Farrell, Camile 1998. Comprehensive Analytical Results Report, Cement Creek Watershed (CERCLIS ID #C00001411347), Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division. Farrell, Camile 1999. Comprehensive Analytical Results Report, Site Inspection Sampling Activities Report, Upper Animas Watershed (CERCLIS ID #C00001411347), Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division. Kimball, Briant 2000. Personal communications regarding USGS Tracer Studies in the Mineral Creek Basin, USGS. Milhouse, Robert. 1998. Personal communications on USGS - BRD results of trout habitat analysis in the Upper Animas basin. Niyogic, Dev K, 2000. Litter Breakdown in Mountain Streams Affected by Mine Drainage: Biotic Mediation of Abiotic Controls. Accepted for 2001 publication in Geological Applications. Nimmo, Del Wayne R., 1998. A Toxicological Reconnaissance of the Upper Animas River Watershed near Silverton, Colorado, U.S.G.S. Open File Report 98-297, 71p. Owen, Bob 1997. Water Quality and Sources of Metal Loading to the Upper Animas River Basin. Colorado Department of Public Health and Environment, Water Quality Control Division Report. Paschke, Suzanne S., Kimball, Briant A., and Runkel, Robert L., 1998, Quantification and Simulation of Metal Loading to the Upper Animas River, Eureka to Silverton, San Juan County, Colorado, September 1997 and August, 1998. Personal Communications and Draft Document to be published in 2001? Sunnyside Gold Corporation, 1985. Use Attainability Analysis of the Upper Animas River. Final Report. Laramie, WY. U.S. Bureau of Reclamation, 1992. Animas River Trace element Toxicity Study. Durango Projects Office, Durango, CO. Walsh, William 1999. Upper Animas River Biological Evaluation Draft Final Report, prepared for San Juan/Rio Grande National Forest, U.S.D.A. Forest Service. Completion date unknown. Wright, Winfield G. and Janik, Cathy J. 1995. Naturally Occurring and Mining - Affected Dissolved Metals in Two Subbasins of the Upper Animas River Basin, Southwestern Colorado. Fact Sheet FS-243-96. U.S. Geological Survey Wright, Winfield G., and Nordstrom, D. Kirk. 1999. Oxygen Isotopes of Dissolved Sulfate as a Tool to Distinguish Natural and Mining-Related dissolved Constituents. USGS Survey Toxic Substances Hydrology Program, Proceedings of the Technical Meeting, Charleston South Carolina, 1999. Witters, H.E., S.V. Puymbroeck, A. J.H.X. Stouthhart, and S.E.Wendelaar Bonga. 1996. Physiochemical changes of aluminium in mixing zones: Mortality and Physiological Disturbances in Brown Trout {Salmo tmttci L.). Environmental Toxicology and Chemistrv Vol. 15, No. 6: 986-996. CHAPTER X - REMEDIATION The last few chapters detail the problems of metal loading on water quality and aquatic life, This chapter discusses what can be done to eliminate or reduce the mine-related loading sources. It also describes a prioritization process that ARSG has conducted for targeting sources in order to get the “biggest bang for the buck” in metal reduction. Remediation can be classified into two broad categories, preventative measures and treatment. Preventive measures are designed to minimize the chemical, physical and biological processes that cause metal loading and increase acidity. The main method, called hydrologic modification, is to try to keep water, oxygen, and acid generating material separate. Other remediation efforts involve treatment of water that is already acidic and/or carries high concentrations of metals. Treatment can be passive where the treatment processes need only periodic maintenance or active where the processes need frequent maintenance and supervision. REMEDIATION TECHNIQUES The Colorado Division of Minerals and Geology has prepared four reclamation feasibility reports for the Upper Animas River Basin (Appendices 10A, B, C, and D). They provide good summaries of what types of remediation techniques are available. Here is an excerpt on surface hydrologic controls (Herron et ctl, 1999, p. 27): Most hydrologic controls are preventative measures in that they inhibit or prevent the process of acid formation and /or heavy metal dissolution. If it is possible to prevent water from entering a mine, or coming into contact with sulfide ores or wastes, this can be the best, most cost effective approach. Diversion ditches are effective where run-on water is degraded by flowing over or through mine waste, or into mine working. Diversion ditches can also be used to intercept shallow groundwater that may enter mine waste. In some cases, mine drainage can be improved by flowing through waste rock. Mine drainage must be sampled above and below a waste rock pile to determine whether the waste rock is actually degrading the water quality. Mine waste removal and consolidation is effective where there are several small mining waste piles in an area, or where there is a large pile in direct contact with flowing water. The method is simply to move reactive material away from water sources. Stream sealing or diversion involves moving the water sources away from reactive materials. Or sealing/lining streams to prevent surface inflows into shallow mine workings through stopes, shafts, or fracture systems. It may include lining or grouting/sealing the streambed or bedrock. Revegetation is often used in combination with other hydrologic controls above. Revegetation by itself can be a very effective method of reducing heavy metal concentrations, particularly where much of the metals come from erosion of mining waste into a stream. Revegetation also reduces the amount of water that infiltrates a waste pile, thereby reducing leachate production. The roots of growing plants also have been shown to produce carbonates through respiration. In addition and often in conjunction to these methods, mine waste piles may be capped and amended with neutralizing agents (e.g. limestone, lime, fly ash). A cap can only reduce surface moisture infiltration. Throughflow and groundwater upwelling can also occur and the impervious cap could result in increased humidity to the mine waste resulting in increased salt formation and eventual loading to nearby streams. The effectiveness of the amendment depends upon many site specific factors. Here is more discussion from Herron e ta l, 1999, p. 30. Subsurface Hydrologic Controls are in-mine measures that inhibit or prevent the process of acid formation and/or heavy metal dissolution into the ground or surface water system. If it is possible to prevent water from entering a mine, or from coming into contact with sulfide ores or wastes, or mixing with contaminated water plumes in the workings, this can be the best, most cost effective remedation approach, because it helps prevent the problem, rather than treating its symptoms in perpetuity. The success of most hydrologic controls depends on ... .understanding the sources and hydrologic pathways of waters that enter the mine workings and discharge from the mine workings through groundwater and surface pathways ...[to] determine how best to segregate or seal off particular water sources in the workings. In-mine diversions are effective where clean groundwater inflows are degraded by flowing through drifts (on veins) and stopes in the mine workings. The concept is to intercept the inflows before they come in contact with metals loading source areas in the mine, thus circumventing metals contaminant production in the mine workings/ore body. The “clean” inflows are then diverted to the surface stream through a collection and piping system. Though in many cases it may not be possible to intercept all inflows before they become contaminated through contact with the ore body, it is often possible to segregate and divert much of the groundwater inflow before it mixes with the contaminated plume. This can greatly reduce the overall quantity of polluted outflow. By significantly reducing mine discharge, it may then become cost-effective and feasible to treat the segregated contaminate plume through passive or semi-passive techniques; the effluent flow is minimized, and concentration may be adjusted for optimum system performance through dilution with part of the diverted clean flows. Grout sealing a fracture inflow zone at a discrete location can prevent groundwater from entering the workings, using proven, existing “ring-grouting” methods and technology. The concept for this technique is to seal water inflows through a grouting program, similar to those used to seal dam foundations, and control water inflows to active underground mining operations. Chemical or cement grout is pumped under pressure into an array of holes drilled radially out from the drift in and along the plane of the water bearing fracture or fracture zones. The grout enters and seals the fracture pathways that communicate with the mine opening. If engineered and executed correctly, the water is prevented from entering the excavation, and is forced far enough back into the rock away from the mine workings so that it resumes its pre-mining course, flowing around the grout “curtain”. Depending on conditions and the layout of the workings, care must be taken to ensure the inflows are not simply diverted to a point where they enter another part of the ore body. Ideally, the grout curtain would be in position where no other lower or upper levels are nearby, and where numerous small fractures or one discrete structure is draining groundwater into the workings along a relatively short section of drift. Bulkhead seals are another type of preventive or “source control” measure. The concept is that geochemical and flow equilibrium will be reached in the groundwater, whereupon anoxic conditions in the flooded workings will prevent or reduce dissolution and transport of heavy metals. Bulkhead seals are designed to prevent discharge to surface water through the adit opening by blocking the flow with an engineered hydrologic plug, flooding the mine. For most inactive mines, bulkhead seals are expensive and require considerable geologic and engineering investigation and characterization. Sites that have simple geology, sound rock, and limited subsurface workings may be amenable to this approach. Sometimes water inflow into mines can be reduced from outside the mine workings. For example, grouting or sealing fracture areas may be done from the surface. A mine near Eagle, Colorado, installed a well near a fracture zone to lower the water table. But all these hydrologic controls may not be enough or may be almost impossible to implement depending on specific characteristics of a site. Discharge from adits may need to be treated, There are a wide range of options, all of which have positive aspects and drawbacks. Generally, treatment involves raising pH levels if they are low and precipitating metals. Here is a summary of passive treatment techniques from Herron e t a l 1999, p. 28; Anoxic limestone drains are the simplest method of introducing alkalinity into mine discharges. Anoxic limestone drains (ALD) are constructed by placing coarse limestone (3/4” - 3”) inside an adit or in a fully sealed trench outside a discharging mine. In order for an ALD to function properly, the mine discharge must be devoid of oxygen. In the absence of oxygen, limestone will not become coated by iron and other metal hydroxides, which can shorten the useful life of limestone. In addition, the mine drainage should be relatively low in dissolved aluminum. Aluminum has been shown to precipitate in ALD’s, causing plugging. It is theorized that very coarse limestone (4”- 6”) should provide large enough pore spaces to minimize or prevent clogging by aluminum. The disadvantage of using larger limestone is the reduced surface area to react with the mine drainage. After the mine drainage exits the ALD, aeration causes precipitation of metals. The increase in pFI due to ALD’s is site specific, but generally does not exceed two standard units. Settling ponds are often overlooked as an effective treatment method. Settling ponds are particularly effective for treating near neutral mine drainages high in total suspended solids (TSS). Aeration of a near neutral pH mine drainage by means of a series of drops, followed by a settling pond can effectively remove iron and other metals that co precipitate with iron. Settling ponds should be designed for a 24-hour or greater retention time wherever possible. Sulfate reducing wetlands are often called bioreactors. These systems treat water through bacterial reduction of heavy metals. Sulfate reducing bacteria (SRB) utilize the oxygen in sulfates for respiration, producing sulfides. The sulfides then combine with heavy metals to form relatively insoluble metal sulfides. The bacteria derive their energy from a carbon source such as cow manure or mushroom compost. There are many other substrates that are an acceptable source of carbon, but most have a low hydraulic conductivity that can result in short circuiting of the system by formation of preferential flow paths. Sulfate reducing bacteria cannot survive in a drainage with pH below 4.5. Highly acidic drainages will require a pH increase before the effluent enters the bioreactor. Sulfate reducing wetlands should generally not be constructed near population centers. These systems commonly produce excess hydrogen sulfide, which can cause undesirable odors up to three miles from the system. When initially started, organics in the substrate discolor the treated water for several months, making water quality appear, to the layman, to be worse than that entering the system, Aqueous lime injection is a passive method to introduce neutralizing agents into mine drainage. This system requires a clean water source. Clean water is passed through a pond containing neutralizing agent, then the high pH effluent is mixed with the mine drainage before it enters a settling pond. This system can be cost effective if the alkaline wastes such as kiln dusts or fly ash are available. Although still in the experimental phase, the method holds promise for some mine sites. Neutralizing materials may also be injected into stopes and drifts. Limestone water jets are an aerobic method of accelerating the dissolving of limestone. In situations where mine drainage flows down a steep slope, the discharge can be piped, and the resultant head can produce a high pressure water jet. The high pressure jet can be either sprayed onto loose crushed limestone, or passed upward through a vessel containing limestone. In both situations, the limestone does not become coated because of abrasion by the water jet, and agitation of the surrounding clasts. The system using a vessel can result in higher alkalinity in the effluent due to greater abrasion. Both system types are in the experimental phase. Oxidation wetlands are what most people think of as S4wetlands”. They differ from sulfate reducing systems in that metals are precipitated through oxidation, and aquatic plants must be established. This treatment method is applicable where the pH of a mine drainage is approximately 6.5 or higher, and where metals concentrations in the drainage are primarily a problem during summer months. Aeration is an important part of the system. The plant materials provide aeration and, when they die, provide adsorption surfaces, along with sites for algal growth. Aeration is best used where the mine drainage pH is about 6.5 or above. Aeration promotes metal precipitation through oxidation processes. Aeration can be accomplished by mechanical means, or simply by channeling the drainage over rough slopes. Mechanical methods require some source of power, which may be generated through wind, solar cells, or hydropower. Aeration methods normally include a settling pond below the aeration component. Mechanical injection of neutralizing agents involves a powered mechanical feeder/dosing system for dispensing neutralizing agents. This type of system requires frequent maintenance, may produce significant quantities of metal sludges, and should be considered “ semi-passive”. Power for the feeder can come from wind, solar, or hydropower. At the Pennsylvania Mine in Summit County, a turbine running in the adit discharge stream demonstrated that hydropower is practical in some situations. Mechanical systems are generally considered only where there are no options for truly passive alternatives. Any high pH material can be used in this type of system. Because of cost effectiveness and sludge characteristics, the most common neutralizing agent is finely ground limestone. Dilution is often overlooked as a treatment method. It can be a cost effective method of treatment, because the neutralizing agent is simply uncontaminated water. Clean water is mixed with the mine drainage in a settling pond, and the resultant pH increases initiates precipitation of metals. A drawback to this method is that the percentage of metals precipitated is significantly less than other methods. Metal removal is site specific, but generally less than 50%. This method is most effective in removing iron, aluminum, copper, cadmium, and lead, but has only slight effectiveness for zinc and manganese. Electro-kinetics is a newer semi-passive method to remove metals from mine drainage. There are several forms of this treatment currently being developed. The electro-kinetic method discussed in this report uses a low-maintenance, self-regulating resin to remove metals from mine discharge. Different metals can be separated by using ion specific resins. Electricity is used to strip metals from the resins, producing a sludge, and allowing re-use of the resin. Land application is a method designed to use natural metals attenuation processes in soils and subsoils to remove metals. Plant uptake, evaporation and transpiration, and soil exchange capacity act to tie up and remove metals. This method is most effective where mine discharge can be spread over a large area to infiltrate into relatively thick soils or unconsolidated deposits. Drainage should be neutral or near neutral to avoid plant toxicity. This alternative is also effective for discharges with high iron and/or aluminum, where pH is approximately 4.5 or above. In addition to these passive and semi-passive techniques, there are active systems that operate in much the same manner but have more mechanical mechanisms and need more maintenance. REMEDIATION IN THE UPPER ANIMAS BASIN Of the 30 projects completed or in progress in the Upper Animas Basin (listed in Table 3.1, Chapter III), 21 are surface hydrologic control projects. There are also four subsurface hydrologic control projects, all using bulkhead seals. Five different passive techniques are in use or have been used in the Upper Animas Basin including injection of a neutralizing agent, anoxic drains, a wetland, a bioreactor, and settling ponds. At some sites a combination of techniques have been utilized. Sunnyside Gold’s treatment plant at the American Tunnel is the only active treatment facility. It consists of mechanical injection of a neutralizing agent followed by a series of settling ponds. Challenges in Doing Remediation Remediation is very site specific and most sites in the Upper Animas Basin offer a plethora of difficult challenges. Many sites lie on steep slopes at elevations 10,000 to 13,000 feet above sea level where it can snow any day of the year, and snow depths can reach 12 to 15 feet in winter. The construction season may last only three to four months. Avalanches are a constant hazard for at least half of the year and some sites lie directly in avalanche paths. Some sites have no vehicle access so that helicopters may be needed to ferry in equipment. Areas around the sites are fragile mountain tundra where heavy equipment can do substantial damage. Few sites have electric power needed for some types of treatment. Hydrologic controls are the preferred method of remediation because they are frequently less expensive and need less maintenance than treatment. Drainage diversions around mine waste piles can be a good, inexpensive partial remediation method, yet it is difficult to totally isolate piles from water. Removal of mine waste piles can be a very effective remediation measure, but where does one put the material? In the Upper Animas Basin, some piles have been scooped up, consolidated, and then capped with clay or soil to reduce water infiltration. However, there are few large, flat areas in San Juan County that could be used as repositories for significant amounts of material. Trucking the wastes outside the region to a landfill would be prohibitively expensive. Another alternative is to mill the mine wastes to remove the offending metals. This alternative is currently being explored. Many mine waste piles lie on steep slopes. As material was dumped from a portal, the piles themselves became conical with steep sides and small flat tops. Their shape makes them difficult to cap or amend with neutralizing agents. Sub-surface hydrologic controls can be very effective, if the underground mine workings are accessible. Most mines in the Upper Animas Basin have not seen any activity in eighty to ninety years, and if entry is still possible, it is very dangerous. There may be no oxygen and the roof may collapse. Yet there are a few sites where sub-surface controls, including grouting or sealing areas above the mine from the surface may be possible, and they are being investigated. Passive treatment must be tailored to a site and to the specific metals needing removal. Some treatment techniques can be ruled out for all but a handful of sites. Only a few sites have relatively large flat areas needed for treatment using settling ponds or wetlands, and these types of treatment lose their effectiveness when temperatures drop well below freezing during much of the year. Techniques such as anoxic drains need less space, but they need more maintenance to prevent them from clogging and are better suited for discharges with low iron and aluminum content. Metals such as zinc and manganese are more difficult to remove because pH must be raised to a high level to make them precipitate. The pH must reach about 11 to get manganese to drop out. Each site needs to be thoroughly characterized and evaluated to determine the feasibility of metal and acid removal. Remediation Feasibility The Colorado Division of Mineral and Geology, with direction from ARSG, has taken a first cut at estimating the feasibility of reclamation for 140 sites (some of which have multiple features) in the Upper Animas Basin. Their four reports - one for Mineral Creek, Cement Creek, Upper Animas above Eureka, and Upper Animas below Eureka (Appendices 10A, B, C, and D) - describe sites, diagram sites, list results of water quality and leachate data (from mine waste piles), and recommend remediation techniques. The reports are quite extensive yet most sites will require more specific process and design engineering before construction begins. In conjunction with and addition to these reports, the ARSG Prioritization committee has characterized and ranked 159 mine waste sites (dumps & tailings) and 174 draining adits relative to one another. While ranking of sites is based upon analytical data determined through sampling, testing and monitoring, the sites can be prioritized by combining ranking information with more subjective attributes. Various weights can be placed on different attributes of a site depending on which attribute is thought to be relatively more important than another. This enables the group to focus remediation towards achievement of specific goals based upon available technology, funding, and property owner cooperation. These spreadsheets (Appendix 10E) are the basis for developing remediation scenarios in the next chapter. While ranking is complete, prioritization is intended to be a dynamic process proceeding prior to each working season. Mine Waste Characterization and Prioritization Mine waste piles were characterized relative to their potential impact on the environment. Certain attributes of each site are listed on the rank and prioritization spreadsheets (Appendix 10F). Potential for contribution of metals and acidity to nearby streams was determined by leachate tests. Ten to twenty samples were taken from various locations of the upper six inches of surface on each mine dump or tailings pile. The samples were mixed to form a composite sample. The composite sample, 150 ml., was mixed vigorously with 300 ml. de-ionized water (2:1 ratio). After allowing clay particles to settle, part of the sample was tested for total acidity, pH, and conductance, The remainder was acidified to determine metal content. (See Herron et al., 1999, for more details on the process.) Some data also exists for 20:1 EPA method 1312 Leach test and Modified 1312 leach tests for several sites. This data was not included in the ranking process because it cannot be compared to the 2:1 leach test. In addition, USGS has done some leach testing using yet another sampling and analysis method. Mine wastes were ranked by metal contributing potential for zinc, copper, cadmium, lead, manganese, aluminum, and iron and pH as determined by the 2:1 leach test. For example, the waste with greatest zinc leachate concentration is ranked number one for zinc. The same site may be ranked number five for lead if it has the fifth highest amount of lead leachate concentration, and so forth. In addition, weighting factors have been assigned for the metals analyzed. Aluminum and iron are considered limiting factors but the sources of these metals are overwhelmingly associated with natural features and processes (See Figures 8.18 - 8.21). In addition, they will automatically be reduced by any treatment method. Reductions may not even be beneficial since their presence downstream may be desirable for scavenging Zn, Cd, and Cu from solution by sorbtion to their precipitates. Aluminum and iron are given a weighting factor of one. Manganese and lead are both given a weighting factor of two because they generally have a moderate potential as limiting factors, while their sources are more specifically identified with mine features than those of iron and aluminum. Lead falls from solution readily in the Animas watershed and will probably not be a limiting factor if treatment for other metals progresses. A handfull of sites appear to be high contributors of manganese. Copper, cadmium, and zinc have high potential as limiting factors throughout the basin and tend to be highly correlated to mine and/or mill features. They come from a multitude of sites. These are given the highest weight factor of three. The other weighted factor, pH, is a strong limiting factor in Mineral and Cement Creeks, but is not as significant in the Upper Animas. Some treatment methods may result in increased pH but much of the low pH is thought to be the product of natural geological processes. It is given a weighting factor of two. To complete ranking, each of the seven metals plus pH were multiplied by their respective weighting factors then added together for each mine waste site. The resulting sum is a measure of the severity of total loading potential. Sites were then ranked for remediation by the weighted sum; the lowest number is given the highest priority. The prioritization was done for each of the three sub-basins and for all the sub-basins lumped together (Combined Rankings). That way remediation can be targeted for specific segments, depending upon in which sub-basin they lie, or by their collective impact on the Animas below Silverton. In addition to the leach test results, many other characteristics are listed on the spreadsheets for the dumps. These are also important considerations in prioritizing sites for remediation, but have not been included as part of a mathematical sum. These include: ♦ site names and locations, ♦ the size of planer surface areas of dumps, ♦ volume of material where estimated by DMG, ♦ distance to ephemeral streams, ♦ distance to perennial streams, ♦ biological potential of nearby streams (i.e. potential presence of aquatic life), ♦ orientation (direction) of slope (indicates when snow may melt ofi), ♦ whether or not a vegetative kill zone exists below, ♦ relative steepness of the site, ♦ ease of access, ♦ whether or not acid mine drainage runs over or through the dump, ♦ potential remediation that might be applied, ♦ rough estimate of cost of remediation. Some of these characteristics require additional explanation. The planer surface areas of dumps were estimated from 1998 USGS Orthophotographic Quadrangle Maps. They are considered to be overestimates because surface disturbances related to roads and portal cut banks often could not be visually distinguished from the wastes. Generally, the entire disturbed area was distinguishable and therefore measured. On the other hand, sites smaller than 80 to 100 square meters were not included because of resolution difficulties. Although there are many small prospects that fit this category, prospects seldom contain high mineral content (otherwise they would have been more extensively mined). The assumption is that the overestimate of the larger waste sites is countered by not estimating the prospect sites. Distances to ephemeral and perennial streams were also estimated using the Orthophotographic Quadrangle Maps. Several characteristics are given a relative rating. Biological potential (of immediate receiving stream) is divided into three categories; low, medium, and high. Likewise, steepness is rated, flat, moderate, or steep. Access is rated 1 through 4, with 1 being easy and four being very difficult. Potential remediation techniques are divided into five categories; capping, amending with neutralizing agents, removal and cleanup, hydrological controls (such as drainage ditches), and consolidation of dumps. The ARSG Prioritization Committee, which is made up of five professionals with extensive experience in implementing mining remediation, estimated typical rates of metal removal for each technique: capping - 25%, amendment - 10%, removal - 90%, hydrologic controls - 20%, and consolidation -10%. These percentages are considered additive if more than one technique is applied to a site. The reduction rates are also considered an average rate for the method over time. Some sites may provide better results; others worse. The spreadsheets show which techniques might be best applied to particular sites. Several sites are currently listed as "no action". After careful evaluation by the Prioritization Committee, these sites were considered having a low potential of contributing metal loads to receiving streams. There are also numerous sites that were identified through Orthophotographic Quadrangle Maps as disturbed areas and have been included on the spreadsheets. Leach test samples were not collected from these sites because best professional judgement determined that metal and pH contributions would be insignificant to receiving streams. Estimated costs for remediation are based on best professional judgement and are site specific. Administration and contingency costs are not included for individual sites but are added to the overall costs of the remediation scenarios described in the next chapter. Disposal costs of any removed material has not been included. (It is possible that the mill at Howardsville may re open to accept wastes for removal of metal sulfides as a marketable product). Four cost ranges have been applied: under $20,000, $20,000 to $100,000, $100,000 to $500,000, and greater than $500,000. The specific remediation estimates for particular sites are shown on the spreadsheets. Adit Characterization and Prioritization Adits have been characterized in method similar to dumps. The results are listed on rank and prioritization spreadsheets for each sub-basin and the complete Basin in Appendix 10F. An attempt was made to sample all draining adits during both high and low flow time periods. Flow measurements were taken at the same time as samples. Sampling was coordinated by the Division of Minerals and Geology and ARSG (See Appendices 10A, B, C, and D). Due to the large number of adits, over 170 (some being quite remote and/or not initially located), a few adits were missed or sampled only at high or low flow periods. High flow samples were also not possible at all sites because of inaccessibility due to deep snow. Some adits had no or unmeasurable flows at low flow. ARSG is continuing to fill in the missing data. Water samples were collected from adits in the Mineral Creek drainage in 1995-1996, in the Cement Creek drainage in 1996-1997, in the Upper Animas drainage above Eureka in 1997- 1998, and in the Upper Animas below Eureka in 1998-1999. All adits were sampled the same day in each sub-basin. High flow samples were taken in late June or July. Low flow samples were taken in September or October. Additional water quality samples were taken at a number of sites by other agencies and companies participating in ARSG. Wherever multiple high flow data exist for a particular site, the data have been averaged. Multiple low flow data were also averaged. All samples were taken at the portal entrances. Adits were ranked in the same fashion as mine waste, using seven metals, pH and the same weighting factors for each metal. Interestingly, when this ranking was compared to a ranking where the weighting factors were removed, the top twenty five adits in the whole Upper Animas Basin remained the same and order of those twenty five changed little. The weighting factors made little difference in the overall results. Adits are also be ranked on the spreadsheets for high flow, low flow, and the combination of high and low flows in terms of metal loading and pH. It depends on what are the analytical purposes and goals of remediation efforts. As with mine waste, other characteristics that may be important to prioritize adits for remediation are included on the spreadsheets such as: ♦ site names and locations, ♦ flow rates during high flow and low flow, ♦ dates of sampling if only one sample was taken during high or low flow, ♦ proximity of receiving streams, ♦ biological potential of nearby streams (i.e. potential presence of aquatic life), ♦ orientation (direction) of slope (indicates when snow may melt off), ♦ whether or not a vegetative kill zone exists below, ♦ whether or not acid mine drainage impacts dumps below the adit, ♦ ease of access, ♦ potential remediation that might be applied, ♦ potential effectiveness of remediation, ♦ rough estimate of cost of remediation. The proximity of receiving stream is rated relatively: instream, near, medium, or far. Biological potential of the receiving stream is rated high, medium or low. Ease of access has a relative scale of 1-4 with 1 meaning easy access. As with mine waste, the potential remediation technique for each site was based on professional judgement of the ARSG Prioritization Committee. The techniques are categorized as bulkhead seals, source controls, passive treatment and active treatment. Hydrologic controls like bulkhead seals and source controls are more desirable because there is minimal operating and maintenance costs. Source controls are means of inhibiting water from leaching metals from underground workings, either by preventing water from entering mines (e.g. re-routing surface waters, pressure grouting inflows) or by collecting in-flowing water before it reaches mineralized surfaces and transporting the water back to surface in an inert conveyance. Where conditions are perfect, such as in deeply situated mine workings where water is entering far from the surface and when the rock has only minimal, small fractures, complete reduction of loading to streams might be expected using bulkhead seals. But this is an unusual situation since many adits are shallow in depth, and the surrounding rock is often highly fractured, naturally or from mining activities. Then water will find alternative pathways around the bulkhead seal. Finding and gathering in-flowing water can be difficult and expensive. First the in-flow must be located by geophysical methods, tracer dye injections, or visual examination from the surface and within the mine. Seldom can all in-flowing water be accounted for, particularly if the underground workings include abandoned stopes and raises. As result of these difficulties, ARSG has determined that on the average, 50% reductions for these two methods would be optimistic for the typical mines and conditions presently known in the Upper Animas Basin. The other two remediation categories are passive and active treatment. Passive treatment generally requires continued long-term maintenance and, on average, will be less effective than hydrological controls. There is a wide range of passive treatment methods available and often two or more methods can be built into the treatment of a single mine drainage. Some treatment methods {e.g. settling ponds) may only remove a small percentage of a single metal whereas a complex system may remove varying amounts of several metals. Given the high elevation, severe winters, high precipitation, steep slopes, and need for continued maintenance and medium renewal, it is estimated that passive treatment systems may average 30% reductions over an extended (20 year) period. There are several methods of active treatment available. All require large initial capital outlays and annual expenditures for operation and maintenance in perpetuity. This category is consider the least desirable approach, although potentially the most effective at reducing metal loading. Active treatment plants are generally designed for reduction of specific metals. As such, they can be very effective for the metal of concern. But it is to be expected that there will be lower percentage reductions for other metals. An 85% average reduction of all metals is anticipated using active treatment methods. In some cases, one remediation method might be tried, such as source controls, but more metals may need to be removed. After the source controls are implemented, passive treatment may be needed. The potential for this additional treatment is noted under Phase 2 of the treatment methods on the spreadsheets. Phase 1 may not be successful or only minimally, Therefore Phase II costs are a summation of the two phases. Several sites are currently listed as "no action . After careful evaluation by the Prioritization Committee these sites were considered having a low potential of contributing metal loads to receiving streams. As with the mine waste characterization, estimated costs for remediation are based on best professional judgement and are site specific. Administration and contingency costs are not included for individual sites but are added to the overall costs of the remediation scenarios described in the next chapter. Four cost ranges have been applied: under $20,000, $20,000 to $100,000, $100,000 to $500,000, and greater than $500,000. Some sites were difficult to fully assess and available remediation methods did not appear to be practical to apply, particularly without further investigation. For these sites, costs reflect the next steps for further evaluation but do not include estimated percentage reductions since the most appropriate remediation method is not known at this time. The specific estimates for all sites are shown on the spreadsheets. The rank and prioritization spreadsheets were designed to focus remediation on locations where the largest benefits could be realized for the effort and resources expended. They were not developed specifically for the UAA and are expected to change as more information becomes available. However, they are very useful for setting up different scenarios describing what metal reductions may be possible and at what cost, if a certain number of sites were remediated. Those scenarios are described in the next chapter, REFERENCES: Herron, Jim, Bruce Stover, Paul Krabacher, and Dave Bucknam, Mineral Creek Feasibility Investigations Report, Colo. Division of Minerals and Geology, Feb. 1997. Herron, Jim, Bruce Stover, and Paul Krabacher, Cement Creek Reclamation Feasibility Report, Colo. Division of Minerals and Geology, Sept. 1998. Herron, Jim, Brace Stover, and Paul Krabacher, Reclamation Feasibility Report Animas River above Eureka, Colo. Division of Minerals and Geology, Oct. 1999. Herron, Jim, Bruce Stover, and Paul Krabacher, Reclamation Feasibility Report Animas River below Eureka, Colo. Division of Minerals and Geology, Nov. 2000. CHAPTER XI - REMEDIATION SCENARIOS Using the characterization and ranking of sites, the effects of remediating multiple sites can be estimated. This chapter compares several different remediation scenarios including costs. The scenarios help determine what metal loading may be "reversible" versus "irreversible". Natural sources of metals are considered irreversible. Some human-related sources could also be called irreversible if they are very difficult and expensive to change. There is the issue of how cost-effective these changes may be and whether or not they would have a noticeable impact in protecting aquatic life. MINING-RELATED METAL LOADING Chapter VIII discusses sources of metals to the Upper Animas Basin. Figures 8.18 to 8.21 show the levels of Al, Cd, Cu, Fe, Mn, and Zn from adits and mine waste. These figures show the maximum amount of each of the six metals that has been identified with mining-related activities. Most remediation methods will remove only a portion of these metal loads. Chapter X discussed the methodology that was used to rank and prioritize specific adits and mine waste piles in the Basin, and discussed relevant technology that could be used to remediate those sources. Cost estimates and amount of reduction corresponding to different technologies are comparable to the actual remediation costs already encountered by SGC, the ARSG, and others in the Basin. (See Chapter 3, Table 3,1.) The ARSG technical work group estimated the potential reductions in loading (as a percentage reduction) that could be achieved by implementing remediation technologies at each adit and mine waste site. Estimated loads contributed by each of 174 adits and 158 waste rock sites are shown in Appendix 11 A. Of those sites, load reductions, applicable treatment technology, remediation option recommendations and cost estimates have been derived for 78 adits and 127 mine waste sites. Those sites that were not included contributed negligible loading, are a substantial distance from streams, and would not be cost-effective to remediate. Treatment of adits is divided into two phases. The first phase treatments are generally simpler and lower cost. They would be applied initially and evaluated for effectiveness, The first phase also includes more detailed investigations of complex adits, such as the Paradise portal on the Middle Fork of Mineral Creek. Although costs would be incurred, no improvements would be anticipated for these few specific sites. Phase 2 treatments would be implemented if phase 1 treatments proved partially or completely unsuccessful. These additional treatments are generally more costly but should be more effective in reducing metals. The estimated cost of remediation of each site is listed as a range in Appendix 11 (and Appendices 10E and 10F). Estimates are based on professional judgement given the technology that could be used and the size and complexity of site. Accessibility affects both cost and the remediation technique selected. As discussed in Chapter X, the cost analysis is a first approximation and uses four cost categories, each with a broad numerical range. The costs for remediation for each site listed in Table 11.1 below is the mid-point of the range for each cost category. One million dollars was used as an estimate for sites whose costs are greater than $500,000. These cost estimates do not include engineering design, operation, or maintenance costs that may be needed. Loading from the Largest Adit and Mine Waste Sources The adits have been ranked, using the weighting factors discussed in Chapter 10, on the basis of both high and low flow loading of seven metals plus pH. Most high flow samples were obtained in June or July, while low flow loads were obtained in September or October. These figures may overestimate low-flow loading since early fall stream flows had not yet dropped to levels seen in winter months. Loads from the Kohler, Bandora, North Star, and Evelyn mines were sampled frequently. Selection of sites to be included for possible remediation is based upon the combined rankings of all sites within the Upper Basin (Appendix 10E). Many sites were previously categorized as "no action" because of their low total contributions and remoteness and/or low concentrations. The loading from the top ranking 34 adits, including a few large loaders lacking either a high or a low flow sampling datum, are displayed in Table 11.1. These are current loading figures and do not include any potential reductions. Ninety one percent of the loading from all adits comes from these top 34 sites. Mine waste piles have been ranked in a similar fashion as adits including the same weighting factors, except that they are ranked by metal concentration determined by the leach test instead of load (Appendix 11 A). Table 11.2 lists the top 26 mine waste sites plus an additional six sites which were added because of their large size and therefore potential for significant load contributions. Leachate concentrations presented in Appendix 10E have been converted to "potential loads". The annual load contributed from waste rock site in Table 11.2 was estimated by multiplying the concentration from the leach test of the waste rock times the surface area of the pile times the average annual runoff from the basin expressed as depth (29 inches). The potential load figures do not include any potential reductions. The 32 waste sites listed contribute 90% of the estimated load from all 158 sites. Units are in pounds per year as opposed to pounds per day used for adits. Estimated loading from mine waste is much smaller than from adits. Approximately eighty-five percent of the mine-related annual metal load in the Upper Animas Basin is from adits, and fifteen percent is from mine waste. As with adits, the appropriate site treatment and corresponding load reductions are based on professional judgement. Again, the estimated costs of remediation fall into the same four categories used for adits. The costs listed in Table 11.2 are the mid-point of the ranges of each category applied to the particular site. Sites with CPDES or reclamation permits are not included in the tables in this chapter. It is assumed that required best management practices and/or treatment at these sites is already in place. Table 11.1 Metal loads from selected adits in the Upper Animas Basin______Pounds per day High Flow Low Flow Mine Phase 1 % Cost $ Al Cd Cu Fe Mn Zn Al Cd Cu Fe Mn Zn Removal 1000's Cement Creek Mogul 80% 1,000 0.04 1.7 14 4 2 1 0.02 0.7 5 1 3 Silver Ledge 50% 300 25 0.09 0.6 222 33 15 4 0.03 0.0 56 11 3 Grand Mogul 0% 60 15 0.15 5.3 33 10 27 1 0.01 0.2 0 0 1 Mammoth 30% 60 1 0.00 0,0 14 2 1 0,00 0.0 16 2 0 Anglo-Saxon 30% 60 0 0.00 0.0 15 10 2 0 0.01 0.0 15 5 1 Joe & Johns 30% 300 0 0.00 0.2 1 1 0 0.00 0,0 1 0 0 Big Colorado 50% 300 1 0.00 0.0 3 3 0 0,00 0.0 6 0 0 Porcupine 30% 60 0 0.00 0.0 14 5 0 0.00 0.0 10 5 1 Evelyn 50% 1,000 1 0.00 0.0 2 0 0 2 0.00 0.0 3 0 0 Lewis property* 50% 60 0 0.01 0,4 2 0 0 0.01 0.4 2 0 1 Total Cement Creek 44 0.29 8.3 320 68 57 10 0.07 1.3 113 25 12 Mineral Creek Kohler 50% 60 33 0.36 30.7 321 10 91 28 0,25 28,3 264 8 78 1st SW Drain-MF Min** 50% 300 60 0.01 0.1 162 3 60 0.01 0.1 162 3 1 North Star 50% 300 0 0.02 0.1 6 16 4 0,02 0.2 6 11 3 Junction Mine 50% 300 13 0.07 2.2 126 3 14 0 0.00 0,1 3 0 0 Bandoru Mine 30% 60 0 0.04 0.1 5 4 10 0 0.02 0.0 2 2 4 Upper Bonner 50% 300 1 0.00 0.0 2 0.01 0.0 2 1 Ferrocrete Mine 50% 300 2 0.00 0.0 31 5 3 0.01 0.0 32 7 1 Paradise ** 0% 60 28 0.00 0.1 246 20 2 28 0,00 0.1 246 20 2 Brooklyn Mine* 30% 300 1 0.01 0.2 8 2 2 1 0.01 0.2 8 2 2 Bonner Mine 50% 300 1 0.01 0.0 2 0.00 0,0 2 0 Lower Bonner 30% 300 1 0.00 0.0 1 0 0 2 0,00 0.0 2 1 1 Little Dora 50% 300 1 0.33 0.9 5 653 48 0 0.00 0.0 0 2 0 Total Mineral Creek 141 0.86 34.4 913 718 175 125 0.32 29.0 728 57 94 Animas above Eureka Vermillion Mine 50% 300 0 0.04 0.2 2 1 9 0 0.01 0.1 1 0 3 Columbus 50% 300 1 0.01 0,3 3 0 9 0 0.02 0.1 1 0 4 Lower Comet 0% 10 2 0.00 0.1 2 2 1 2 0.00 0.0 1 1 1 N side of Calif. Mtn. ** 30% ' 60 4 0.01 0,0 5 2 4 0.01 0.0 1 5 2 Sound Democrate 50% 60 0 0.00 0.1 0 4 1 0 0.00 0.0 0 2 0 Mountain Queen 50% 300 0 0.00 0.2 1 0 1 0 0.00 0.1 0 0 0 Silver Wing 30% 0 0 0.00 0.1 0 0 0 0 0.00 0.3 1 1 1 Bagley 30% 300 0 0.01 0.0 0 13 7 0 0.01 0.0 0 6 3 Senator 30% 300 0 0.00 0.0 21 7 0 1 0.00 0.0 23 14 2 Total Animas above Eureka 8 0.08 1.0 30 33 29 8 0.06 0.7 29 29 15 Animas below Eureka Royal Tiger 50% 300 5 0.04 0.8 0 3 7 0 0.00 0.1 (3 0 0 Pride of the West 30% 60 0 0.01 0.0 0 0 3 0 0.01 0.0 0 0 2 Little Nation 30% 300 0 0.00 0.0 9 2 1 0 0.00 0.0 4 1 0 Total Animas below Eureka 6 0.06 0.8 9 5 10 0 0.02 0.1 4 2 3 GRAND TOTAL 198 1.3 44.5 1,272 825 271 143 0.46 31.0 875 113 124 No low flow data. Low flow loads are extrapolated from high flow data ** No high flow data. High flow loads are extrapolated from low flow data. XI - 4 Table 11.2 Metal loads from selected mine waste rock sites in the Upper Animas Basin Load in pounds per year Site Name Acres % Reduction Cost A1 Ctl Cu Fe Mn Zn $1000 Cement Creek Galena Queen 1.09 90 300 154 36.8 832 6,895 0.0 6137 Kansas City #2 0.46 40 60 159 7.1 39 3,979 0.0 1172 Hercules 1.26 90 300 163 30.6 168 6,712 0.0 4711 Upper Joe & Johns 0.02 40 300 2 0.1 2 19 0.0 23 Grand Mogul - East 0.53 35 300 47 2.0 29 745 0.0 385 Kansas City #1 0,48 40 60 82 1.2 19 1,618 0.2 282 0.1 108 Black Hawk 0.20 50 60 82 0.5 6 124 Lead Carbonate 0.62 55 300 120 0.8 27 1,228 0.0 179 0.0 113 Henrietta 3 0.86 20 60 217 0.7 107 4,972 0.0 49 Ross Basin 0.15 10 60 9 0.3 18 234 168 Lark 0.66 90 60 18 0.8 40 886 0.0 oc f**; 0.1 Prick of the Rockies 0.05 45 60 7 0.1 0 7 Henrietta # 7 1.19 40 300 101 0.8 25 1,685 0.0 159 Mogul 1.16 35 300 51 1.2 32 942 0.0 261 Cement Creek Total 8.72 1,210 83.1 1,343 30,421 0.5 13,754 Mineral Creek 118 Brooklyn 0.25 91) 300 58 0.8 8 993 117 Bullion King:Lower 0.86 90 300 641 6.0 14 9,945 190 629 Upper Browns Trench 0.11 40 10 27 0.1 8 198 3 9 20 Congress Shaft 0,35 40 60 11 0.2 16 109 11 176 163 Brooklyn Upper 2.57 20 60 661 3.1 38 9,909 Upper Browns 0.51 90 60 82 0.3 5 1,610 6 25 66 Little Dora 1.39 30 300 94 0.4 43 452 471 105 Brooklyn Lower 0.86 20 60 110 0,6 9 672 122 Mineral Creek Total 7 1,684 11.5 142 23,888 1,095 1,135 Animas above Eureka Ben Butler 0,34 40 300 28 0.8 8 225 1 165 131 Silver Wing 1.21 50 60 98 1.0 123 393 172 Tom Moore 0.19 90 60 15 0.3 1 8 43 73 0 7 18 Eagle 0.07 90 60 1 0.1 1 32 95 Lucky Jack 0.70 90 60 16 0.6 3 14 Animas above Eureka Total 3 157 2.8 136 639 256 482 Animas below Eureka 80 70 Clipper 0.09 90 60 6 0.2 7 57 Buffalo Boy 0,38 90 60 17 0.8 24 13 73 141 99 95 Ben Franklin 0.37 90 60 81 0.4 13 612 50 255 Caledonia 0.57 30 60 23 1,0 15 1 0 664 Sunnyside 2.50 90 1,000 40 2.3 10 536 Animas below Eureka Total 4 168 4.6 69 706 815 1,224 GRAND TOTAL 22 3,219 102 1,691 55,655 2,167 16,595 METAL REDUCTION SCENARIOS Using the information from Tables 11.1 and 11.2 and Appendix 11 A, the results of several different remediation scenarios can be estimated. The scenarios shown on Table 11.3 include phase 1 treatment of the top 34 adits and of the top 78 adits, phase 2 treatment of the top 34 adits and of the top 78 adits, phase 1 treatment of the top 32 mine waste piles and of the top 127 mine waste piles. Costs listed under phase 2 include the costs of both phase 1 and phase 2 treatments since phase 2 would not be implemented until after phase 1 had been tried. For the adit scenarios, loading figures are derived from low-flow samples because that time period is of most concern. Out of 174 adits sampled, only 134 had measurable drainage during low-flow samplings. The cost estimates listed on the tables above and in Appendix 11A do not include engineering design, operation, or maintenance costs. Remediation experience in the Basin has shown that administration costs are substantial and cost overruns have been encountered owing to larger than expected volumes of material or other unanticipated problems. The scenarios listed below include a 30% administration cost and a 20% contingency cost added to the sum of the individual site costs. Table 11.3 Summary of metal loads from adits and combined mine waste for the Animas Basin above A72. Adits Mine Waste (Low flow loads)__ Total load of A l, Cd, Cu, Fe, Mn and Zn in pounds/year Top 34 469,321 Top 32 79,429 134 Adits 517,127 158 Sites 88,602 Estimated cost to remediate in $1000's Phase 1 Phase 2 Top 34 $ 12,555 $ 21,000 Top 32 $ 8,175 Top 78 $ 21,000 $ 32,280 Top 127 $21,960 Load Removed in pounds/year Phase 1 Phase 2 Top 34 169,331 235,565 Top 32 50,494 Top 78 180,124 250,235 Top 127 54,618 Cost/pound/year * Phase I Phase 2 Top 34 $ 74.14 $ 89.15 Top 32 $ 161.90 Top 78____$116.59 $129.00 Top 127 $ 402.10 *Total cost divided by load removed. Clearly there are diminishing returns in treating both adits and mine waste. The top 34 adits account for 91% of the load and under phase 1, it would cost $12.5 million to treat them. To treat the additional 9% of the load would add $8.5 million. The contrast is more stark under mine waste. The top 32 sites account for 90% of the load and would cost just over $8 million to treat. Treating the additional 10% would add almost $14 million. The phase 2 adit scenario includes removal of large quantities of Fe and Al from the Paradise portal. In fact, 81% of the difference in load removed between phase 1 and phase 2 for adits can be attributed to phase 2 remediation of the Paradise alone. Under phase 1, no reductions in metals from the Paradise are anticipated because a more thorough investigation of the site will be the first step. With the exception of this one site, there is little difference in reductions of metals between phase 1 and phase 2. Moreover phase 2 would only be implemented if phase 1 did not result in projected reductions. Therefore, without the Paradise and its associated phase 2 remediation cost of $1 million, the difference in costs between phase 1 and 2 can be thought of as a range of costs associated with a total loading reduction for adits of approximately 170,000 to 180,000 pounds per year. Remediating the Paradise portal along with two other similar sites, the Ferrocrete mine, and a small prospect on the Middle Fork of Mineral Creek is problematic. They are all shallow workings in the Mineral Creek drainage and lie near the base of valleys. The mines are thought to have intersected the relatively shallow groundwater that wells up at valley bottoms creating the area’s infamous iron seeps and bogs. Metal loading may well be the result of natural geological processes that is carried into the mine through groundwater infiltration. While treating naturally occurring source loads (coming from adits) may be beneficial, discharges with high iron and aluminum concentrations are expensive to treat because of high production of sludge which needs disposal plus frequent system maintenance, These adits are also collapsed, indicating that they were constructed in highly fractured rock making it unlikely that bulkhead seals would provide significant reductions. Successful remediation of these sites would be very difficult and expensive. EFFECTS OF REMEDIATION ON WATER QUALITY Figure 11.1 shows the estimated reductions of the six priority metals at the four gages if remediations were implemented on the top 32 mine waste piles and phase 1 remediations were implemented on the top 34 adits. Figure 11.2 shows estimated reductions if remediation were implemented on the top 32 mine waste piles and phase 2 remediations were implemented on the top 34 adits. The description below summarizes the results. Effect of Remediation on Total recoverable Aluminum at A 63 esDo - j FMAMJJA5 OND Month j------C A 6 3 ------New Cone | New Conc~| New NewConc] ------Month Monti) ------■C A56 ■C C MC 34 Effeet of Remediation onTotal Recoverable Cadmium at ASS at Cadmium onTotal Recoverable Remediation of Effeet New Conc|New New Cone]New ------M i r t h Month ------CCC4B CC48 C A 72 Effect of Remediation on Total Recoverable Cadmium st Cadmium Total Recoverable on Remediation ofEffect XI- VO ! I I _jr= : \ \ V -- / ------' ------New Cone. Total Cone. New | V__ Month Month ------atAS8 stM 34 New Cone, Total Total Cone, New | CABS Â\ Â\ y \ \ / \ ------| / / C M 3 4 / ------\ ------| / Effectof Remediation on Total RecoverableCu Effectof Remediation on Total RecoverableCu — ' JFMAMJJASOND JFMAMJJASOND 50 90 • 100 100 - XI- 10 New CorelNew ------Month — CASS ..... I FMAMJ JASOND FMAMJ J Effect ofRemediation on Total RecoverableIron atA68 ------8000 ------6000 ------4000 ------2000 10000 120D0 120D0 --NewCone] ------Month Month C A 7 2— ------Cooc| New CCC48 CC48 Effecto Remediation onTotal Recoverable Iron at XI- 11 remediated _ - ___ ------______------______N ew Cone| _ N ew C one] ______------Month Month C i O t CASS Aluminum atM34 | | Alum inum at A 63 ______— Effect o f Remediation on Total Recoverable Effectof Remediationon Total recoverable fmabjjasond ______— •¡ — _ _ ------~ ~ ~ J F M A M J JASOND JASOND J M A M F J ------______------I - — ------0 7 0 0 0 6000 5 M B 6 0 0 0 ------4 0 0 0 - — ------_ _ ------3 9 0 0 1 00 0 2000 ! N ew Cone | N ew Cone [ ------Month Month C A 7 2 C C C 4 8 A lum inum at A72 j------\ ^ ! Aluminum atCC4S " X ^ Effectof Remediation on Total Recoverable FMAMJJASOND Effect ofRemediation onTotal Recoverable J J XI- 14 --N ewCone} Bontfi Bontfi Month CASa ———Core] Me» ------C M 3 4 Effect of Remediation onTotal Recoverable Cadmium at AS3 at Cadmium onTotal Recoverable Remediation ofEffect -He»[ Cone ------North Month CCC4S CC48 C A 7 2 ------t e wC o n e j Effect of RerrediatjoB on Total Recoverable Cadmium at Cadmium Recoverable Total on RerrediatjoB ofEffect a - 15 91* IX Month C A 7 2 ------New Cone] Effect o Remediation on Total Recoverable Iron at Effect of Remediation on Total Recoverable Iron at ASS CC48 12000 ...... - .....-...... -...... -...... -...... — ...... 1 0 0 0 0 ------ 8000 ------6000------ 4000 ------ 2000 ------ 0 -I— r ~ .~~ ■■ '■ iii.it ------■ JFMAMJJASOND Month Month CCC45------N ew Cone] I . . .. c ASS------New Cone I Remediation of combined mine waste and either the phase 1 or phase 2 adit scenarios will have very little effect on reducing the concentration of Al, Cd, Cu, Fe, Mn, or Zn at A68. Cd and Mn will continue to exceed chronic TVS under the average streamflow condition in the late winter and early spring. Zn will continue to exceed both acute and chronic TVS year-a-round. Cu, when corrected for the dissolved fraction, should meet TVS. Al and Fe meet aquatic life TVS criteria. A substantial amount of Cd, Mn, and Zn enters the Animas River from unidentified, diffuse sources between Arrastra Gulch and A68. The largest tailings piles (previously ponds) in the Basin lie near the river along this stretch. The site is permitted and has undergone extensive remediation work over the past ten years. In the fall of 1999, a trench was dug to bedrock above the tailings, and a barrier and drainage system was installed to capture groundwater flow that might enter the piles. Data collected after 1999 was not used for the UAA. Therefore, the impacts of the most recent remediation work are unknown. In addition, it is doubtful that one year’s data would be enough to identify changes in water quality due to these actions. Given the minimal remediation potential identified upstream, an evaluation of the “reversibility” of the load of Cd, Mn, and Zn that enters the Animas River between Arrastra Gulch and A68 will be needed to determine if water quality can be substantially improved at A68. Cement Creek at Silverton, CC48 Remediation of combined mine waste and the phase 1 adit scenario should reduce levels of Cd, Cu, and Zn below levels encountered in Cement Creek before SGC began treatment of upper Cement Creek at the AT plant. Implementation of the phase 2 scenario in Cement Creek will have only a small beneficial effect beyond phase 1 on the concentration of Cd, Cu, and Zn at CC48, unless phase 1 is significantly unsuccessful. Figures 11.Id and 11.le indicate that either the phase 1 or phase 2 remediation scenario will have little effect on levels of Fe or Mn. Remediation will have no effect on the level of Al. Concentrations of all six metals will remain above both acute and chronic TVS for aquatic life. Mineral Creek near Silverton, M34 Remediation of combined mine waste and the phase 1 adit scenario should reduce levels of Cd, Cu, and Zn to concentrations that meet chronic TVS during average stream flow. The current level of Mn is less than TVS for aquatic life. Implementation of phase 1 reductions should lower the level of total recoverable Fe, however it will continue to exceed aquatic life TVS year-a-round. This analysis shows that remediation is not expected to measurably change the concentration of dissolved recoverable Al, which will continue to exceed acute TVS criterion during the winter. Implementation of phase 2 reductions will primarily lower levels of total recoverable Fe, however, Fe will continue to be higher than TVS for aquatic life. Remediation of the combined mine waste and the phase 1 adit scenario should reduce levels of Cd, Cu, and Zn during average stream flow. Cd and Cu concentrations will be close to chronic TVS for aquatic life but may exceed those criteria in the spring, Zn will continue to be at a level that exceeds both acute and chronic TVS for aquatic life year-a- round. Fe and Mn concentrations may be slightly lower, however, total recoverable Fe will continue to exceed TVS year-a-round. Mn currently is lower than the TVS. Neither phase 1 nor phase 2 remediation is expected to have much effect on the current level of dissolved Al. Aluminum would continue to be a limiting factor, If a sufficient amount of the load of Cd, Mn, and Zn that enters the Animas River between Arrastra Gulch and A68 can be “reversed ” further improvements in those constituents should be seen at A72. Reductions in pH Current TVS for pH is 6.5 to 9.0, pH is a measurement of hydrogen ions based on a logarithmic scale (base 10) so that a whole number increase, from 5.0 to 6.0 for example, signifies a ninety percent reduction in the concentration of hydrogen ions. The presence of iron is a major factor in determining pH. In winter, pH is 6.1, 5.5, and 4.8 for segments 3a, 4a, and 9b respectively, Attempts were made to model potential improvements in pH due to remediation, but they were unsuccessful Because of the low potential reductions identified for iron above A68, it is uncertain if pH may be improved. The possibility of improving pH is higher at M34 and A72, because of the potential for reductions in iron loading, but the amount of improvement is probably quite small. Reaching the TVS standard is highly unlikely. APPENDIX HA REMEDIATION SCENARIO WORKSHEETS 1. ADITS 2. MINE WASTES This information is available on the CD-ROM only CHAPTER XII - RECOMMENDATIONS The recommendations of this report are based on a combination of four components of the UAA - the biological assessment, the water chemistry assessment, the limiting factors analysis, and the remediation analysis. Most of the recommendations are directed to the Colorado Water Quality Control Commission (WQCC), but a few are aimed at other stakeholders: the San Juan Board of County Commissioners, U.S. Forest Service, and the U.S. Bureau of Land Management. The recommendations for WQCC lie in three areas, segmentation, use classifications and water quality standards. CHANGES IN SEGMENTATION While the UAA has focused on stream segments in the Upper Animas Basin that have impaired water quality, many small tributaries to Mineral Creek and the Animas River can meet cold water aquatic life class 1 Table Value Standards (TVS). Some of these small streams have improper or non-existent use classifications and standards. For example, about nine small tributaries to the Animas River from Maggie Gulch to Elk Park (tributaries to Segments 3a, 3b, and 4a), have been inadvertently omitted from descriptions of any segment and therefore have no applicable use classifications and standards^ Several tributaries to the upper part of Mineral Creek have no aquatic life classifications, yet they are located in non-mineralized areas and have very good water quality. To bring the omitted segments under regulatory compliance and to more accurately portray the current water quality situation, it is proposed that all tributaries to the Animas River from Maggie Gulch to Elk Park be placed under one segment description, segment 6, with exceptions made for those areas that do not meet TVS for aquatic life class 1. The exceptions fall under: segment 7, the drainage of Cement Creek, segment 8, Mineral Creek above South Mineral Creek including tributaries on the east side of the creek except for Big Horn Creek, and the Middle Fork of Mineral Creek, segment 9, Mineral Creek from South Mineral Creek to the Animas River, currently called segment 9b. Segment 6, therefore includes tributaries to Mineral Creek on the west side of the drainage, which is outside the caldera, except for the Middle Fork of Mineral Creek. It includes the South Fork of Mineral Creek and Big Horn Creek which is only tributary included on the east side of Mineral Creek. The differences in water quality between streams in segment 6 and those in segments 7, 8, and 9 are closely tied to differences in geology of the areas those streams drain. One drainage that has been omitted from earlier descriptions that does not meet aquatic life class 1 TVS is Arrastra Gulch. Only one of the top loading sources associated with mine sites is located in the drainage, and water quality improvements may be minimal. In addition, water quality in Arrastra Gulch is different from that measured in segment 3a, where the gulch joins the Animas River. Thus, it is recommended that a new segment, 3c, by created for this drainage. The other proposed segmentation change is on the lower part of the Animas. As the river leaves the Animas Canyon at Baker’s Bridge, the topography and geomorphology change drastically - from a confined, high gradient canyon to an open, flat floodplain. Land use patterns change drastically as well - from a steep canyon with little development to a heavily used agricultural area that is quickly becoming urbanized. It is proposed that the dividing point between segment 4b and 5a be moved upstream from Junction Creek, located below the flat valley, in the middle of Durango, to Baker’s Bridge. Thus, segment 4b would cover most of the Animas Canyon, and segment 5a would cover the urbanized and urbanizing area from Baker’s Bridge to the exterior boundary of the Southern Ute Indian Reservation. DERIVATION OF WATER QUALITY STANDARDS Figure 11.1 in the last chapter shows the expected reductions in total recoverable metals given phase I remediation of the top 34 adits and top 32 mine waste sites, This scenario has been used to derive recommended water quality standards for different segments. The scenario was chosen because it addresses the sites representing 90% of the identified mine-related loading sources. The estimated reductions are predicted, not assured. If phase 1 remediation is only partially successful, more expensive measures listed under phase 2 will be needed meet recommended standards. The biggest difference between phase 1 and phase 2, besides additional costs, would be the successful remediation of the Paradise portal, discussed in Chapter XI. Overall, total metal load reductions under the chosen scenario total 220,000 to 230,000 pounds per year for an estimated cost of $20 to $28 million, not including operating and maintenance costs. Few of the current property owners have the financial means to remediate their sites. It is unknown where the financial resources may come from to address the majority of these sites. In addition, as described in Chapter I, there are third- party liabilities involved in addressing draining adits that make it very difficult for non- owners of sites to become involved in remediation. The metal loading under this scenario is “reversible”, but from a financial standpoint, will be difficult to attain. Table 12.1 below summarizes numerically the graphic information displayed by Figure 11.1. It shows the peak concentrations for different metals in two seasons for each segment. The initial total recoverable concentrations have been converted to dissolved concentrations by applying known monthly dissolved to total percentages derived from data collected at different gaging stations. The next two columns show the total recoverable concentrations after the remediation has occurred and those concentrations are also converted to dissolved values. The last column shows TVS values for the different metals. The numbers in bold are the recommended standards. Generally, the standard is equal to which ever is greater, the dissolved concentration after remediation or TVS. Wherever the standard is equal to the remediation concentration, a temporary modification will be needed. They are noted on the table with a TM. It is proposed that the temporary modification be set equal to the current ambient concentration as shown on Table 12.1 for a period of six years. After six years, progress of remediation and resulting changes in water quality should be re-evaluated. Since metal concentrations in Cement Creek are expected to rise when Sunnyside Gold turns off its treatment plant at the American Tunnel in compliance with the consent degree, the proposed ambient water quality has been modeled using data from before Cement Creek was treated. These concentrations are designated on the table with “Pre- CD”. TVS (ch) — 87 87 — (ch) TVS =750 (ac) TVS TVS (ac) =750 (ac) TVS TVS (ch) = 87 = 87 (ch) TVS =87 (ch) TVS =750 (ac) TVS - (ch) 87 TVS =750 (ac) TVS TVS (ch) = 87 = 87 (ch) TVS TVS (ch) = 87 =87 (ch) TVS »750 (ac) TVS 750 = (ac) TVS Ambient Ambient TVS for same same for TVS (ch=chronic; ac=acute) month and location location and month ] 1 ug/l} ug/l] [0 [0 %; %; %; %; [Gug/ %; %; 0 0 100%; [6038 ug./[] [6038 100%; ug/l] [4201 100%; 0 21%; [607 ug/l TM] ug/l [607 21%; 56%; [2224 ug/I ug/I [2224 56%; ™ l ug/l] [2279 0%; fDissolved Concentration dissolved; Potentially Attain«!] Peak month % month Peak @ @ Range of Max. Max. of Range 818 to Feb. Feb. to 818 & @ July @ 512 to Oct. @1178 Oct. to 512 @ July @6038 2893 June June 3972 @4201 after remediation remediation after concentration {Total 2279 @ Oct. to 804 @ July Oct. @ 64 lo June @ 174 @ June lo 64 @ Oct. May @ 2623 to Feb. Feb. to 2623 @ May Oct. to 2137 @ June concentration and value value and concentration values) Feb. to 767 @ May Dec. @ 79 to April @ 222 @ April to 79 @ Dec. Month Month & ug/l] ug/l] ug/l] ug/i] [0 %; %; 0%; [176 [176 0%; 0%; {232 ug/l] {232 0%; — itecomuieuueu— 100 %; [7340 ug/l; set set ug/l; %; [7340 100 set ug/l; [4188 100%; 56%; [2536 ug/l} [2536 56%; tcurrent dissolved dissolved tcurrent 7340 ug/l] 7340 0%; [2398 [2398 0%; Concentration] 0 ambient @ pre CD = = CD pre @ ambient = CD pre @ ambient ug/l] 4188 [665 21%; dissolved; dissolved; Peak monih % monih Peak aitui (aß 166 (aß 819 to Feb. Feb. to 819 @ July @ 551 to Oct. @ @ 1223 Oct. to 551 @ July @4188; pre-CD = 4188 = pre-CD @4188; 4529 Oct. @ 71 to June @ @ 176 June to 71 @ Oct. (Total conc. values) conc. (Total 2398 @ to Oct. 577 June Nov. @ 89 to April @ 232 @ April to 89 @ Nov. June @ 2147 to Oct. Oct. to 2147 @ June June Month & Piange of Month Piange & values concentration before remediation remediation before oinerwisenoiea ; ug/i utuess Oct. Oct. 16-Mavl5 15 16-Oct. Mav May 16-Oct. 15 16-Oct. May Oct. 16-Mayl5Oct. 7340 Feb. to 2606 @ May 16-Mayl5 Oct. Oct. 16-Mayl5Oct. @ Feb. to 761 @ May May 16-Oct. 15 16-Oct. May Oct. 16-Mayl5 Oct. May 16-Oct. 15 16-Oct. May Season May 16-Oct. 15 16-Oct. May ?s m ?s 68 A75 CC48 A72 MC34 A Segment (au vatu Stream XII-4 8 Ambient Ambient TVS (ch) = 2.2 2.2 = (ch) TVS =10 (ac) TVS TVS TVS =1.0 (ch) TVS =? (ac) TVS TVS (ac) — 5.8 — (ac) TVS =.7 (ch) TVS X2 = iac)TVS 7.7 — (ac) TVS TVS (ac) = (ac) TVS =8.4 (ac) TVS and location location and (ch=chronic; ac=acute) = 1.5 (ch) TVS TVS for same month month same for TVS % ug/1] = 1.9 (ch) TVS [.6 0 97%; [.7 ugl] [.7 97%; ug/1] [1.5 97%; —1.8 (ch) TVS 97%; [2.1 ug/1] [2.1 97%; ug/1] [2.3 97%; ug/1] [1.9 97%; TM =1.9 TVS (ch) JDissolved ug/1] [1.3 97%; 97%; [2.5 ug/I] [2.5 97%; 97%; Peak month month Peak Concentration Attained] dissolved; Potential!}' to April @ 2.1 @ April to Range of Max. Max. of Range .8 0.9 to June, Oct. @ @ Oct. June, to 0.9 & 1.5 to April @ 2.6 @ April to 1.5 @ % 1.3 ? @0.7 June @ 1.8 to Aug. @ 2.4 @ toAug. 1.8 @ June No exceedances No No exceedances No July @ 0.9 to Oct. @ @ 1.3 Oct. to 0.9 @ July Jan. Jan. @0.6Oct. to @ 1.0 Aug. July. concentration and value after after value and concentration values) concentration (Total April to 0.0 Dec.,Jan.,Feb.@ Feb. @ Feb. Month Month remediation % No exceedances No 97%; [1.4 ug/1] [1.4 97%; 97%; 14.0 tig/I] 14.0 97%; ug/1] [2.4 97%; 1.9 @ April to 0.2 @ Jan. leurrent dissolved dissolved leurrent ug/1] 2.0 97%;[ 97%; [2.7ugd] 97%; Ï1.lug/i]97%; ug/I] [1.7 97%; 97%; {4.0 ug/ï] {4.0 97%; dissolved; dissolved; Concentration] Peak month month Peak % Year average =1.4 average Year Aug. @ 2.1 to June 3.2 3.2 June to 2.1 @ Aug. 2.0 @ 1.4April. to 0.8 @ Jan. [1.4 ugfl] 97%; July @0.4 to Oct. @ 1.1 @ Oct. @0.4to July Pre-CD = 4.1 = Pre-CD (Total conc. values) conc. (Total 2.7 Feb. 1.3 to May 3,1 3,1 May to 1.3 Feb. Pre-CD =4.1 Pre-CD concentration values values concentration Dec,Jan. @ 1.7 to April @ @ toApril 1.7 @ Dec,Jan. Month Month Range of & before remediation remediation before samples exist) samples Year (only 5 5 (only Year Oct 16-Mayl5exceedances No May 16-Oct. 15 16-Oct. May May 16-Oct. 15 16-Oct. May 1.7 @ Oct. to @ 1.1 July. Oct. 16-Mayl5Oct. 2.4 @ April to 0.9 @ Jan. May 16-Oct. 15 16-Oct. May May 16-Oct. 15 16-Oct. May May 16-Oct. 15 16-Oct. May toOct. 0.1 @ July Aug, Oct. 16-May 15 16-May Oct. Season 68 3c Amstra A75 CC48 16-Mayl5 Ctet. A72 MC34 16-Mayl5 Oct. A (all values in ug/1 unless otherwise noted) noted) otherwise unless Needed ug/1 Standard;Stream Modifications in Temporary-= TM Bold Recommended values (all Stream Segment waste sources) waste XII-5 Stream Season Month & Range of Peak month % Month & Range of Max. Peak month % TVS for same month Segment concentration values dissolved; concentration and value after dissolved; and location before remediation [current dissolved remediation [Dissolved (ch=chronic; (Total conc. values) Concentration] (Total concentration values) Concentration ac=acute) Potential!}7 Attained] A68 Oct. 16-Mayl5 Mar @23 Mar. diss. = 33% Nov. @3 to Mar. @21 Mar. diss. = 33% TVS (ch) = 17 r& u r /i] (Mar. (8i 21) f7.0uRfll TVS (ac) = 54.9 May 16-Oct. 15 June @ 23 June diss. =47% Oct. @5 to June @ 16 June diss. =47% TVS (ch) = 7 n iu ^ ii (June 16) [8 02/11 TM TVS (ac) = 21.6 MC34 Oct. 16-Mayl5 March @ 67 Mar. diss. = 67% Feb. @ 0 to May @ 32 May diss. = 29% TVS (ch) = 23 TM f45 usfl] (May @32) F9.2 usfi\ TVS (ac) = 38 May 16-Oct. 15 Oct @65 June diss. = 32% Aug. @4 to June, Jun. @ June diss. = 32% TVS (ch) = 9 TM [21 ug/X] 17 [5.2 ug/I] TVS (ac) = 13 TM (June @ 17) CC48 Oct 16-Mayl5 May @ 86 May diss.= 93% Jan. @ 25 to May @ 65 May diss.^ 93% Ambient [80 ug/I] Pre-CD (Maj1 @ 65) [60 ug^l) — same May 16-Ox 15 June @90 June diss. = 87% Oct. @ 42 to June @ 69 June diss. - 87% Ambient [79 ug/IJ Pre-CD (June @69) 160 ug/1] = same A72 Oct. 16-Mayl5 April @49 April diss. = 32% Dec. @ 2 to May @ 30 May diss. = 29% TVS (ch) = 10 TM [16 us^l (May @ 3 0 ) 18-7 ug/1] TVS (ac) = 67 May 16-Oct 15 Oct @ 34 June diss. = 28% July @ 7 to June @ 15 June diss. = 28% TVS (ch) = 3 [lOng/l] (June (ä> 17) [4 U2/1) TM TVS (ac) = 19 A75 Oct. 16-Mavl5 No exceedances No exceedances TVS May 16-Oct. 15 No exceedances No exceedances TVS 1000 (ch=chronic; (ch=chronic; ac=acute) temp. mods. No =1000 (ch) TVS temp. mods. No TVS (ch) = 1000 (ch) TVS = 1000 (ch) TVS TVS (ch) = 1000 (ch) TVS TVS for same same for TVS location and month = 1000 (ch) TVS = (ch) TVS Ambient TVS (ch) = 1000 (ch) TVS 56%; [1681 ngfl] [1681 56%; fDissolved Concentration Attained] ug/1] [1409 48%; Peak month % month Peak dissolved; Potentially ugfl] [1741 44%; 53%; [805 ug/1] [805 53%; - (ch) TVS 1000 2343 to Jan. @ 3001 3001 @ Jan. to 2343 4983 to Jan. @ 9230 @ Jan. to 4983 ugfl] [6184 67%; Ambient @ @ TM remediation 525 @ June to @ 127 Oct. NA Nov. @ 156 to Mar. @ 641 @ Mar. to 156 @ Nov. NA Month & Range of Max. Max. of Range & Month after value and concentration values) concentration (Total TM 1518 @ June to @ 1325 July TM July @ 3569 to Oct. @! 6342 @! Oct. to 3569 @ July ugfl] [4122 65%; 3957™ May May 56% May leurrent dissolved dissolved leurrent 48% 2936 @ to Oct. 2242 @ June dissolved; dissolved; Concentration] 53% 67% 65% 44% @ Feb. to @ 1843 May Peak month % month Peak 6959 6959 @ 205 to April @ 673@ toApril 205 NA 2583 to Feb. @ 4949 @ Feb. to 2583 4149 to Oct. Oct. to 4149 % @ @ @ 1661 @ June @ 2438 to Oct. @ 3737 @ Oct. to 2438 @ June July July (Total conc. values) conc. (Total concentration values values concentration before remediation Nov. @10393 Jan. to 5412 @ May Pre-CD=same May @ 1982 to Feb. 5007 @ Feb. to @ 1982 May Pre-CD — same Pre-CD— Oct. Oct. 16-Mayl5 May 15 16-Oct. May May 16-Oct. 15 16-Oct. May 534 @ toJune @162 Oct. NA Oct. 16-May 15 16-May Oct. May 16-Oct. 15 May 16-Oct. May 16-Oct. 15 16-Oct. May Aug. & June to @ 1545 July Season Month Range & of Oct. Oct. 16-Mayl5 May 16-Oct. 15 16-Oct. May 68 Stream Segment A CC48 A75 Oct. 16-Mavl5 MC34 (all values ugflunless in otherwise noted) Bold = Recommended Stream Standard; TM= TemporaryModifications Needed A7215 Oct. 16-May XII-7 Stream Season Month & Range of Peak month % Month & Range of Max. Peak month % TVS for same Segment concentration values dissolved; concentration and value after dissolved; month and location before remediation (current dissolved remediation [Dissolved (ch=chronic; (Total conc. values) Concentration} (Total concentration values) Concentration ac=acute) Potentially Attained] A68 Oct. 16-May 15 May @1194 to 100%; [2589 ug/1] May @ 1207 to Mar. @ 2379 100%; [2379 ug/1]; TVS (ch)= 1881 Mar.@2589 TM TVS (ac) = 4916 May 16-Oct 15 July @564 to Oct @1073 100%; [1073 ug4] July @ 540 to Oct. @1063 300%; [1063 ug/1] TVS (eh) = 1668 TVS (ac) = 4132 MC34 O ct 16-May 15 Nov. @413 to Feb. @545 100%; [545 ug/1] April. @ 0 to Mar. @ 387 100%; [387 ug.A] TVS (ch) — 2214 TVS (ac) = 6837 May 16-Oct 15 June @ 104 to Oct. @ 335 100%; [335 ug/1] 100%; [274 ugA] TVS (ch) = 2054 June (a}0 to Oct. @ 274 TVS (ac) - 5586 CC48 Oct. 16-May 15 May @ 884 to Dec. @2071 100%; [2071 ug/ij May @ 896 to Nov. @ 1870 100%; [1870 ug/1] Ambient May 16-Oct 15 June (2> 429 to O ct r®;1765 100%; [1765 ug/1] June (ai 420 to Oct. @ 1687 100%; [1687 us/ll Ambient A72 Oct. 16-May 15 May @ 682 to Mar. @ 100%; [1402 ug/l] May @ 631 to Mar. @ 1333 100%; [1333 ug/1] TVS (ch) — 2497 1402 TVS (ac) = 7420 May 16-Oct. 15 June@3IltoOct. @831 100%; [831 ug/1] July @ 179 to Oct. @ 757 100%; t757ug/I] TVS (ch) = 2022 TVS (ac) = 5462 A75 Oct. 16-May 15 May 16-Oct. 15 . ______TVSfor same monthand location (ch=chronic; ac=acute) TVS (ch)= 157 TVS (ac) 179 TVS (ch)= 130 TVS (ac) =148 TVS (ch)= 212 TM TVS (ac)= 234 TM TVS (ch)= 180 TM TVS (ac)=199 TM Ambient Ambient Ambient Ambient TVS =(ch) 244 TVS (ac) =278 TVS =(ch) 176 TVS (ac) =200 TVS (ch) = 190 TVS (ac) ~210 TVS =(ch) 155 TVS (ac)« 171 TVS (ch) =79 TVS (ac)= 87 ug/1] ^ i ______[Dissolved dissolved; Peakmonth % Concentration Attained] 99.7%; [1040ug/1 Potentially TM] 89%; [456ug/I TM] 99%; [204ug/I] 88%; [131 99.6%; [667ug/I] 97.9%; [648ug/I] 100%; [326 ug/1 97%; [648ug/I TM] TM] (8x ------1042 MonthRange& of Max. concentrationand (Totalconcentration value afterremediation values) Nov. @471 toMar. @ M y@ 246to Oct. @ 457 Jan. @ 51 toMar. 206 July@ 0to Oct. @ 146 Dec. @ 610to April @ 670 June@ 428 to Oct. 662 668 May@ 376 toMar. July@ to Oct.190 ^ 3 2 6 =BegmmenJed Stream Standard; TO= Temporary Modifications Needed Peakmonth % dissolved; leurrentdissolved Concentration] 99.7%; [1115 89%; [452ug/1] ug/i] 99%; [497ug/1] 88%; [263 ug/1] 99.6%; [1015 97.9%; [917ug/I] 100%; [836 ug/1] 97%; [393 ug/1] 100%; [256ug/1] 100%; [161 ug/1] TM d 1 100%; [200ug/1] TM Bol, : 426to Mar. : 1118 concentrationvalues (Totalconc. values) Month &Range of beforeremediation Nov. @508 to Mar @ July@261 toOct @ 508 Nov. @368to Mar. @502 July @ 58to Oct. @299 Jaa @653 toApril @ 878 Pre-CD= 1020 July@611 toOct @773 Pre-CD= 936 July @246 to Oct. @405 May 836 May @ to 189 Feb. 256 Aug@ to 124 Oct. @ 161 year UlS|fUDleSS| rn0ted>r O ct 15 16-May May 16-Oct. 15 Oct. 16-Mayl5 May 16-Oct. 15 Oct. 16-Mayl5 May 16-Oct. 15 Oct. 16-Mayl5 May 16-Oct. 15 Oct. 16-Mayl5 May 15 16*Oct. Year (only 5 samplesavail.) fon^ UfSoln 1 Stream oucam season Month &Ranee of Peak mnnth d p. Segment ^ r A68 MC34 CC48 A72 A75 3c Arrastra X II-9 It is unknown how much pH will change with remediation, but any changes are likely to be minimal Iron is a major driver of pH, and iron reductions under the remediation scenario are projected to be small. Therefore, minimum pH standards are proposed to be set equal to current, seasonal pH values, except when those values are greater than 6.5. In those cases, TVS would apply. Table 12.2 shows the proposed pH standards. Table 12.2 85th Percentile pH (s.u.) Values and Standards to Apply Segment Season pH Standard to Apply 2 6.5 TVS 3a Apr-Oct 6.4 6.4 Nov-Mar 6,1 6.1 3b Year NA NA 3c Year 7.4 TVS 4a Apr-Oct 6.1 6.1 Nov-Mar 5.5 5.5 4b Year 7.5 TVS 7 Year 3.8 3.8 8 Year 4.3 4.3 9b Apr-Oct 6.1 6.1 Nov-Mar 4.8 4.8 Model Results versus 85th Percentile The Colorado Water Quality Control Division uses the 85,h percentile method in determining ambient water quality. Essentially, 15% of all data is greater than and 85 A of all data is less than the value used as the determinant value for ambient water quality. Thus, some high peak concentrations may not be noted or taken into account. While this method may be appropriate where minor amount of data exist, it provides little understanding of the changes in water quality over the seasons. The model used in the UAA and used for developing the recommended standards gives a much clearer understanding of the seasonality of water quality. It allows standards to be set seasonally which can be more protective than setting one single standard that must accommodate attainable water quality concentrations during the season when they peak. In addition the 85th percentile method could only be applied to the last three years of data because actions taken by Sunnyside Gold have changed water quality. The model was adjusted to factor in these changes. Thus, the model is based on eight years of water quality data which is more representative of year to year changes in the hydrological cycle. A comparison of the 85* percentile values and the peak modeled values, which are used for recommending standards during low-flow time periods, shows that in many cases the values are very similar for segments 3a, 4a, and 9b. concentrations are dissolved except iron which is total recoverable. Units ~ ug/L) A68 (3a) | A72 (4a) | M3 4 (9b) Metal Model 85th Model 85* Model 85th A1 232 115 665 554 2536 2097 Cd 2.7 3.0 2.4 2.0 1.4 1.6 Cu 11 9 16 20 45 49 Fe 673 227 5007 3701 494 9 4233 Mn 2589 2500 1402 1600 545 471 Zn 1115 900 836 723 497 482 CHANGES IN USE CLASSIFICATIONS It is recommended that the new proposed segment 3c is classified for cold water aquatic life class 2 and recreation class 1. No fish have been found in Arrastra Gulch and zinc, cadmium, and copper exceed TVS during portions of the year. The sources of these metals may be considered irreversible. It is recommended that the goal of cold water aquatic life class 1 be removed from segment 4a, and the use classification of aquatic life class 2 be retained. A few brook trout have been found near the bottom of the segment. As remediation takes place, more brook trout are expected to be found, but water quality will not support a thriving fishery nor a diverse population of other aquatic organisms. Under the remediation scenarios, dissolved aluminum and total recoverable iron will continue to exceed TVS and chronic Biological Thresholds for all trout. Zinc concentrations will continue to preclude all trout except brook. Copper concentrations will exceed chronic Biological Thresholds for brook trout. It is recommended that the cold water aquatic life class 1 use classification be removed from segment 9b, and the use classification of aquatic life class 2 be instituted. There is ample evidence that water quality will not achieve TVS in a twenty year time given any remediation scenario. Identified mining sources contribute very little aluminum to Mineral Creek. Even if one hundred percent of these sources were removed, dissolved aluminum would still reach dissolved concentrations three times higher than the acute TVS and Biological Thresholds for all trout. In addition, under the remediation scenarios, total recoverable iron will continue to be twice TVS and Biological Thresholds for all trout. Currently, no trout have been found in this reach during recent surveys and minimal macroinvertebrates have been found. After completion of all proposed remediation, the macroinvertebrate community diversity and density would remain minimal. Table 12.4 lists the proposed changes in the format used by WQCC for segmentation, use classifications and standards. :2n(oh)~52ft- 5QDQ AND 01 =11 / 0 rrnrl pffective / ^ = QUALIFIERS ^ p mtiLfiQQ/QZ ¿Ifrh\=fi70 TEMPORARY 6 y c a r p b e g in n inU g atil 6/1/07 i F rrilrJi)=2.4 S ß Q & 4 r Tem p mod effective MODIFICATIONS Syoarc beginning ■2n(oh]-65^ ■ inlil ■ R/1/Q 7I r . i f r M am bientm quality e t a l s . for all 3 years6/30/01: beginning existing Tem p m od effective for Jl 2 H g(ch)=0.0l(tot)N i{ c h ) = TA V g S ( a c ) = T V S Znfch^SO Maylfitnfict 15: Maylfitnfict r.rttrin\= M nfrt-ii-TVS Ni(ac/ch)=TVSA g ( a c ) =Ag(ch)=TVS(tr) T V S ai(ao/ch)-5‘10 Se(ac/ch)=TVS Zn(ac/ch)=TVS Se(ch)=10(Trec)Ag(ch)=TVS(tr) A g ( a c ) = T V S __ PKlcfl established for segm ents * 4a and -Po(ch)-1000(Troa); Zn(ch)-??6f r.iifct11=5 Fe(ch~t=3S507n'rti)=330 M c h t e l V S 1 R i n M a y 1 5 : M n(oh)~1003-M n/ar./rhteTVS Pb and zinc that is directed tow ard m aintaining and «9 ifi»nM av15: METALS A g ( c h ) ~ T V S U nnW OIK OIK nnW U ES OOftVO OC Of JliflA r.nfi-hfeTViffoctive S untii June Eeí^MOOQ ZnIcQ)=S50 r\r* AifçyzSlü A Crlll(ac/ch)=TVSCrVl(ac/ch)=TVS Cd(cW acj=TVS Cd(ao/ch)-1.S m » i n a n Al(acteb)=TVSA sích)-100(Trec) ^ rS n ^ n tS tio n S ss* e d aluminum, ^jum ^copper jon, lead, Existing am bient quality for all m etals as of February 1 4 .199S: Effective until June 30, 2001 : achievinganfl_4b. w ater qualityand-B&. standards established for segm ents 3a, , m anganese, and zinc that is directed tow ard mai CrVI(acich)=TVSCu(ac/ch)=TVS rrl'3P.)=1VCrlll(ac/ch)=TVS S As(ac)=100{Trec) Al(ac/ch)=TVS The concentration ofdissolved aluminum. ' Effective untilExisting Ju n e 30, am 2001: bient quality tor all m etals as of February 14,1995. CrVI(ac/ch)=TVSCu(ac/ch)=TVS C d ( c h ) =Crltl(ac)=50(Trec) T V S Cd(ac)=TVS(tr) As(ac)=50fTrec) = 0 .0 5 t B = 0 . 7 5 S = D .0 0 2 S 0 4 = 2 5 0 N O f = 1 0 C 1 = 2 5 0 NO S = 0 . 0 0 2 B = 0 . 7 5 INORGANIC C N = 0 . 0 0 5 Cl2(ac)=0.019Cl2{ch}=0.011 NH3(ch)=0.02 NHjiac)=TVS C N = 0 . 0 0 5 Cl2{ch)=0.011 NH3(ch)=0.C2Cyac)=0.019 NH3(ac)=TVS Cl2(ch)=0.011C N = 0 . 0 0 5 Cyac)=D.019 NH3(ac)=TVSNH3(ch)=0.02 1 - M a r 3 0 : a n d - Qrt 30 -Qrt 1-M ar 3D: 1 p H = 5 5 - 9 - Q tinv F.Coli=200/100ml PHYSICAL pH ~ 6 5 9 .0 D .0(sp)=7.0 mg/l D .O . = 6.0 mg/l BIOLOGICAL pH = 6.0-9.0F.Coli=2000/100ml Kn-J p H = 6 1 - 3 J o H = 6 4 - 9 - 0 F.Co!i=200/100ml¿pr D.O. (sp)=7.0pH - 6.5 mg/i 9 Q D .O . = 6.0 mg/i F.Co!i=200/100ml pH = 5.B-9.0 F.Coli=200/100m l D O . (sp)=7.0mpH = 6.5-9.0 g/l D O. = 6.0 mg/1 Aq. Ufo Coid Aq Life Cold 2 Recreation 2 A griculture Aq Life RecreationCold 1 2 R ecreationA griculture 2 R ecreationW ater 1 SupplyA griculture Aq Life C old 1 UP UP C r e e k t o t h e c o n f l u e n c e w i t h E l k C r e e k . point im m ediately above the confluence with M (nera! M ainstem of the A nim as River, including w etlands, from a point immC reek ediately toM a above ineral point Creek. theim m confluence ediately above w ithC the emconfluence ent with C r e e k . Gulch to imm ediately above the confluence with Cem ent point im m ediately below the confluence with M aggie except for specific listings in S ogm ont 1 S egm entfe. im m ediately above the confluence with M aggie Gulch, and w etlands, from the outlet of D enver Lake to a point M ainsiem of the A nim as River, including all tributaries including all w etlands, lakes and reservoirs, w hich are within the W em inuche W ilderness Area. All tributaries to the A nim as R iver and Florida River, 3b M ainstem of the Animas River, including w etlands, from a 3a M ainstem of the Animas River, including w etlands, from a Stream Segm ent D escription BASIN: ANIMAS AND FLORIDA RIVER R E G I O N : 9 XII-12 years beginning 6/30/01;am existing bientm quality e t a l s . forall years beginning 6/30/01:am existing bientm quality e t a l s for all Tem p m od effective for 3 Tem p m od effectivefor 3 Se(ac/ch)=TVS A g ( a c ) = T V S Ag(ch)=TVS(tr)Zn(ac/ch)=TVS Ni(ac/ch)=TVSSe(ch)=10(Trec) A g ( a c ) = T V S Ag(ch)=TVS(tr)2n(ac/ch)=7V S Fe(ch)=300(dis) Fe(ch)=1000(Trec)Pbfac/ch)-TVS M n(ch)=50(dis)H g(ch)=0.01(tot) N i ( c h ) = 7 V S Fe(cb)=1000(Trec) Fe(ch)=300(dis)Pb(ac/ch)=TVS M n(ch)=50(dis)H g(eh)=0.01(tot) Cd(ac)=7VS(tr) A s ( c h ) = 5 0 Cd(ch)=TVSCr!ll(ac)=50n'rec) CiVI(ac/ch)=TVSCu(ac/ch)=TVS A s(ac)=50frrec)Cd(ac)=TVS(tr)C d ( c h ) = 7 V S S = Q .0 0 2 B = 0 . 7 5 N 0 z = 0 . 0 5 N O 3 = 1 0 C l = 2 5 0 S O 4 = 2 5 0 NH3(ac)=TVSNH3{ch)=0.02Cyac)=0.019 CI2(ch)=D.011C N = 0 . 0 0 5 NH3(ac)=TVSNH3(ch)=0 02 C)2 ^ thhirtario«: 111 .ir-n ciT Par1f ByreDf a, frDm cf>urcos t0 confluonoo w ith M inora! M ainstemthe of confluence therronfli A m nim nnn with as with River, Junction Elk Creekincluding C to iuak. wB etlands akefs Rrirtno from th» SouthernM exico Ute border. Indian R eservation boundary to the Colorado/New M ainstem of the A nim as River, including w etlands, from the and resarvniix rtf rm ek Pjrouser.r^k Pl^yn^n, ii^h D enver l_aks> Main«om -^-i. ||jm-f a nd M innie -G ulch All trihirtariag inrinrfinfl the trihiitario*’ w etlandsimm ediately lakas ar.rt above ^«qfypjra M annia tn ,ho Anim as Riuar M ainstem nfthe A nim as Riimrfrom tho ^ouro? In ihn n, ^ l ^ rspnmpn,s 3c 7 B anH Q Mainstem, including-ati teoutartoe, wotlando,Cw tningh-amCrook lakoo Pr^ni- from and thoir rosorvoirc, P ^u|rjor sourm». Crpg!- offn Cinnam thr'irrnnfinnni-v»r W hitohcrart on Crook- G ulch and Mob thcjV rim j: lakes, and reservoirs, from the source to the confluence with the Denver Laka € fensf>rw fr River. Fir-iynn M r.rirh ainstom of Milii Bie lii i rjnlrh. A nim nnfrnm Mnngio ttin Gulch rm .r-n ^ f i-, oulj3t Animas River M ainstem of C em ent C reek, including all tributaries, w etlands from theSouth source M ineral to a Creek.point im m AlLtributaries ediately above on the» the «.act confluence ciHo nfjhis with M ainstem of M ineral Creek,^gm apL including oL M aataL all tributaries C reek ¡ni-.ii irtin^and «/atianrte w etlands lakoe anH wetlando. Iflkn^ nnrl fmm n?l,roc to -, p ^ ’ 4fiwiod:3to|y-abovotf^uamq at! tho tnbutanac. Creok;oonfluoncoSogm all lakeswotl^n^ ontc with 7Mand through inorai roGorvoks Crooli;Himr 0. min ainctomtho draim s g n nroas dcscritud in of Mil] -M ainctom of South M inora! C fssk including all tributarie s- X I I - 1 3 b e g in n i n g 6 / 3 0 / 0 1 : effective for 3 ys ar-s p H - 6 . 2 9 . 0 Aifr*^=2550C ü t e h iFWch^SOOQ = 4 5 7iVr:h)=500 Aliar7cM=TYS Fe Fe(ch)=300(dis)Fe(ch)=1000(Trec) M n ( c h } = 1Hg(ch)=0 O O O ( T re c ) 01(tot) Fe(ch)=300(dis)Fe(ch)=1000(TPb(ac/ch)=TVS Mree) n(ch)=50(dis) Hofch^O .O Iitot) Pb(ac/ch)=TVSM n(ch)=50{dls)M n(ch)=1 OOOftrec) Hg{ch)=0.01(tot) Fe{ch)=300(dis)Fe(ch)=1000(T ree) Pb(ac/ch)=TVS M n(ch)=1000(Trec) Fe(ch)=300{dis)Fe(ch)=1000(Trec)M n(ch)=50(dis) rrffafJr.h^TVSfdisi Cri!l(ac/ch)=TVS Gd(ac)-TV S(4f) Z n ( a c ) = T V S A i{ a c ^ c h )As(ch)=lOO(Trec) ~ T V S Cufacfch)=TVS C d ( c h ) =Crlli(ac/ch)=TVS T V S CrVl(ac/ch)=TVS Cu(ac/ch)=TVS Cd(ac)=TVS(tr) CrIII!ac)=50(Trec)CrVI{ac/di)=TVS As(ch)=50(Trec) Cd(ac)=TVS(tr)C d ( c h ) = T V S As(ac>=5D{Trec) Cu(ac/cti)=TVS C d ( c h ) =Crlll(ac)=50(Trec) T V S CrVI(ac/ch>=TVS Cd(ac)=TVS(tr) Crl!!(ac)=50(Trec)CrVl!ac/ch)=TVSCufac/ch>=TVS As(ac)=50(Trec) Cd[ac)=TVS{tr)C d ( c h ) = T V S A s(ac)=50(Trec) C d ( c h ) =Crlll(ac)=50(Trec) T V S CrVl(ac/ch)=TVSCu(ac/cu)=TVS Cd(ac)=TVS(tr) As(ac)=50(Trec) 03=10 5 = 0 . 7 5NO^Û.05 N 0 3= 1 0 .C 0 l 2 = 2 5 0 S Q 4 = 2 5 0S = 0 . 0 0 2 N 0 2 = 0 . 0 5 S = 0 . 0 08 2 = 0 . 7 5 S 0 4 = 2 5 0 N 0 3= 1 0 C l = 2 5 0 S = 0 . 0 0B 2 = 0 . 7 5 N02=0.05 S 0 4 = 2 5 0 N 0 j = 0 . 0N 5 C l = 2 5 0 S = O .O C 2 B = 0 . 7 5 N 0 2 = 0 . 0N 5 0 3= 1 D C l = 2 5 0 S 0 4 = 2 5 0 S = 0 . 0 0B 2 = 0 . 7 5 < a c ) = T V S ml mg/l 100 / a n d PHYSICAL 2000 BIOLOGICAL NUMERIC STANDARDS D .O .j 6.0 mg/l D .0.(sp)=7.0 mg/l pH = 6.5-90F.Coli=2000/100m l D.O. = 6.0D.O. mg/l(sp)=7.0 mg/l pH = 6.5-S.0F.CoIr=200/100m i D.O.= 6.0 mg/i D .0.(sp)=7.0 pH = 6.5-9.0F.Coli= 2 2 1 1 2 C lassifications Recreation Aq Life Cold 2 A griculture A q Life CRecreation old 1 Water Supply Water A griculture Recreation Aq Life Cold 2 W ater Supply A griculture UP D e s i g Creek from th e ^ lïl^ r tl’rS ^n d G^na & »from * * the * source to W avte* H gy»^ L“ J * Cfeek- and Nar> Draw i s ~ = £ s ~ = - r R E G I O N - 9 BASIN: ANIMAS AND FLORIDA o n /c p Stream Segm ent Description 1 3 c . 14. 15. M ainstem of Purgatory Creek from • xir-15 While the recommendations above are directed at WQCC, there are other measures that different government entities could implement besides mine site remediation that should improve water. For example, a substantial amount of metal loading is attributed to surface runoff from quartz-sericite-pyrite and acid sulfate areas. Only a small proportion of loading has been identified as runoff from mine waste sites. Certain best management practices could be implemented by federal land managers and San Juan County to minimize metal loading, These practices would be most effective if initiated in quartz- sericite-pyrite and acid sulfate areas (See map, Chapter VII, Figure 7.1.). They include: ♦ reducing or eliminating grazing which reduces ground cover and thereby accelerates erosion and exposure of oxygen and water to metal sulfide bearing substrates . (Some draining adits, especially in Cement Creek, carry metal concentrations toxic to grazing animals), ♦ maintaining water bars on county roads, especially when they are first opened in spring, ♦ implementing erosion control and revegetation measures on public, ♦ restricting road development in mineralized areas, especially where highly mineralized areas could be are exposed, ♦ implementing county-wide erosion control and construction revegetation standards. Other recommendation include: ♦ Ensuring that remediation of sites has minimal impact on historic values by working closely with the San Juan Historical Society and San Juan County, ♦ Monitoring of silver concentrations that may be increase because of recently re introduced upwind cloud seeding operations, O c c a sionally after meetings, discussions amongst stakeholders would be carried over to the “Miner’s Tavern" where local brews could be " s a m p le d ” . H ere are some labels designed specifically for the Animas River Stakeholders Group that give a sense of the local flavor. Animas River “ It Ain't No Down Stream Beer”