RESULTS OF THE AQUATIC MONITORING PROGRAM IN THE SOUTH PLATTE RIVER FOR SPCURE, 2007-2008
May 2010
Prepared for:
South Platte River Coalition for Urban River Evaluation c/o Brown and Caldwell 1697 Cole Blvd., Suite 200 Golden, CO 80401
Prepared by:
Aquatics Associates, Inc. 3013 E. Mulberry Street Fort Collins, Colorado 80524 970.493.2626
Aquatic Monitoring Program for SPCURE, 2008
TABLE OF CONTENTS Page
EXECUTIVE SUMMARY iv
1.0 INTRODUCTION 1
2.0 METHODS 8 2.1 Site Characteristics 8 2.2 Fish Populations 8 2.2.1 Sampling and Analysis 8 2.2.2 Mercury and Selenium Fish Tissue Study 10 2.3 Macroinvertebrates 11
3.0 RESULTS 15 3.1 Site Characteristics 15 3.2 Fish 16 3.2.1 Populations 16 IBI Scores 25 Fish Disease 26 3.2.2 Fish Mercury and Selenium Concentrations 26 Mercury 27 Selenium 27 3.2.3 Fish Summary 30 3.3 Macroinvertebrates 31 3.3.1 Kick Samples 31 Community Characteristics 31 Community Metrics 45 3.3.2 Rock Basket Samples 48 Community Characteristics 48 Community Metrics 49 3.3.3 Macroinvertebrate Summary 50
4.0 REFERENCES 53
APPENDICES
LIST OF TABLES
1 Biological Monitoring Sites in the South Platte River for SPCURE, 2007 and 2008 3
2 Sampling Dates and Types of Samples Collected at South Platte River Sites for SPCURE, 2007-2008 4
3 Percent Abundance of Fish Species, Total Collected, Number of Native Species, and Index of Biotic Integrity (IBI) Scores at South Platte River Sites, Fall 2008 17
Aquatics Associates, Inc. i May 2010 Aquatic Monitoring Program for SPCURE, 2008
4 Whole Body Selenium Concentrations in Selected Fish Species from South Platte River Sites, Fall 2008 21
5 Comparisons of Selenium Concentrations in Fish for the South Platte River, SPCURE 2008 vs. Data Reported for Similar Streams 22
6 Occurrence of Predominant and Important Macroinvertebrate Species Collected from South Platte River Sites, Spring 2008 and Fall 2007 and 2008 32
7 Summary of Key Community Parameters and Indices for Macroinvertebrate Samples Collected from South Platte River Sites, Fall 2007 and 2008 33
8 Summary of Key Community Parameters and Indices for Macroinvertebrate Samples Collected from South Platte River Sites, Spring 2008 34
9 Summary of Key Community Parameters and Indices for Macroinvertebrate Samples Collected in Rock Basket Samples from South Platte River Sites, Fall 2008 34
LIST OF FIGURES
1 SPCURE Biological Monitoring Sites in South Platte River 2
2 Percent Abundance of Numerically Dominant and Important Native Fish Species Collected at South Platte River Sites, Fall 2008 18
3 Comparisons of Numbers of Fish and Native vs. Non-native Species Collected at South Platte River Sites, 2008 19
4 Fish Index of Biotic Integrity (IBI) for South Platte River Sites, 2008 20
5 Percent Relative Abundance of Macroinvertebrate Taxonomic Groups for Kick Samples from South Platte River Sites, Spring and Fall 2007 and 2008 35
6 Macroinvertebrate Density and Total Number of Taxa for Kick Samples from South Platte River Sites, Spring and Fall 2007 and 2008 36
7 Comparison of Select Macroinvertebrate Community Parameters for Kick Samples at South Platte River Sites, Fall 2007 and 2008 37
Aquatics Associates, Inc. ii May 2010 Aquatic Monitoring Program for SPCURE, 2008
8 Comparison of Select Macroinvertebrate Community Parameters for Kick Samples at South Platte River Sites, Spring 2008 38
9 Percent Relative Abundance of Macroinvertebrate Taxonomic Groups for Rock Basket Samples from South Platte River Sites, Fall 2008 39
10 Macroinvertebrate Density and Total Number of Taxa for Rock Basket Samples from South Platte River Sites, Fall 2008 40
11 Comparison of Select Macroinvertebrate Community Parameters for Rock Basket Samples at South Platte River Sites, Fall 2008 41
APPENDICES
A Photographic Documentation
B Fish Population Data
C Fish Tissue Mercury and Selenium Data
D Macroinvertebrate Community Data
Aquatics Associates, Inc. iii May 2010 Aquatic Monitoring Program for SPCURE 2008
EXECUTIVE SUMMMARY
The initial results for the aquatic bioassessment conducted by Aquatics Associates, Inc. (AAI) for urban Segments 6c and 14 of the South Platte River (SPR) are presented in this report. This study began in the fall of 2007 and will be conducted over a six-year period (2007-2012) for three major stakeholders of the South Platte Coalition for Urban River Evaluation (SPCURE), including Centennial Water and Sanitation District (CWSD), Littleton/Englewood Wastewater Treatment Plant (L/E WWTP), and Xcel Energy (Xcel a.k.a. Public Service Company of Colorado).
The study area includes 13 sampling sites on the mainstem of the SPR from just below Chatfield Reservoir to approximately 0.5 mi. downstream from I-70. Sampling sites were chosen to represent reaches upstream and downstream from key dischargers (CWSD, L/E WWTP, and Xcel’s Arapahoe and Zuni Plants), major tributaries (Bear Creek and Cherry Creek), and significant stormwater outfalls. The bioassessment was designed to provide SPCURE with an evaluation of the existing biological integrity of the fish and macroinvertebrate communities in SPR Segments 6c and 14 and develop a data base over the next five to six years that can be used to support appropriate water quality standards. This study will also complement previous aquatic studies conducted by GEI Consultants, Inc. (GEI) for Segments 6 and 14, the Denver Department of Environmental Health (DDEH), and the current studies being conducted by Metro Wastewater Reclamation District (Metro) for Segment 15. One of the major goals of the bioassessment is to define a reference condition by developing a “constructed” reference site for the SPR study area that will be developed using the best score for each of the selected site-specific core benthic community metrics which will be used to evaluate the relative impairment at each of the SPR sites. Results of this analysis will be provided at a later date when sufficient data have been collected.
The bioassessment components included fish population surveys in the fall and sampling of macroinvertebrate communities in both the spring and fall seasons, with sampling occurring during low flow periods in March and October/early November. The initial fish sampling event was conducted in the fall of 2008, while macroinvertebrate sampling was conducted in both the spring of 2008 (secondary sampling) and in the fall of 2007 and 2008 (primary sampling). Spring and fall macroinvertebrate collections were performed at 6 and 13 sites, respectively, using a kick net. The fall macroinvertebrate program also included artificial substrate sampling using rock baskets conducted at the same six sites sampled in spring. Fish sampling was performed at 8 of the 13 study sites, with 6 of these sites also the same as sampled in spring. The 2007 program included only macroinvertebrate kick sampling in the fall. The first complete (all components) year of sampling occurred in 2008. In addition, whole body mercury and selenium analyses of fish from selected trophic levels (omnivore/bottom, omnivore/water column,
Aquatics Associates, Inc. iv May 2010 Aquatic Monitoring Program for SPCURE 2008 insectivore, and piscivore) were also conducted as part of the bioassessment, and samples were collected concurrent with the fall 2008 fish sampling event. Results of the 2008 fish tissue analyses for mercury and selenium are presented in this report. The resulting five-year data base will be used to support the establishment of appropriate water quality standards for these metals.
Fish population data will also be used for addressing the temperature standards issue for SPR Segment 14. The Colorado Water Quality Control Division (CWQCD) proposal to classify Segment 14 as Aquatic Life Warm 1 with a temperature standard of Water Stream Tier I is to be protective of the johnny darter that is found in this Segment. L/E WWTP, in cooperation with Xcel and other members of the SPCURE, proposes to change the temperature standard from Tier I to Tier II and to adjust the seasonality of the temperature criteria.
The fish community in the urban reach of the SPR appeared most influenced by the widely fluctuating stream flows and channelization. Ten of the 22 fish species collected in the study area are native to the South Platte River Basin in Colorado. White suckers were the predominant species at sites upstream from site S21/22, whereas fathead minnows, longnose dace (common at most all sites), and carp generally became more abundant at sites N18 through N47. Creek chubs were well represented and generally evenly distributed from site S51 downstream. Interestingly, both the Iowa darter (Colorado species of special concern) and johnny darter were found in good numbers in the SPR study area. The Iowa darter was found at only one site S76, while the johnny darter was collected at six of the eight sites. The incidence of black spot disease was very low, with the highest incidence occurring at site S21/22. Regardless, all fish collected appeared healthy and in good condition. The IBI analysis showed spatial differences with the lowest IBI scores noted at sites S76 and S21/22 suggesting that these sites may be more impacted than the other sites. Fish population results are not indicative of stress due to in-stream temperature modifications from municipal/industrial effluent discharges into the SPR urban reach.
Mercury concentrations in almost all the fish samples were less than method detection limits, with only two estimated values being reported. Selenium was detected in the fish tissue samples and was slightly elevated compared to suggested criteria; however, concentrations were generally lower than found in fish from other similar drainages. Nonetheless, the fish populations sampled in 2008 showed no apparent stress due to the slightly elevated selenium concentrations reported for these fish.
The macroinvertebrate community was represented by a total of 17 major taxonomic groups in the fall kick samples, with 12 groups each collected in the spring 2008 and in the fall 2008 rock basket samples. The most taxa were found in the fall kick samples when 63 and 66 taxa were collected compared to 60
Aquatics Associates, Inc. v May 2010 Aquatic Monitoring Program for SPCURE 2008 taxa in the spring. Taxa richness was higher in the rock basket samples (71 taxa), which was due to higher numbers of midge taxa.
The fall macroinvertebrate community was dominated by caddisflies in 2007 but in 2008 mayflies were dominant with dipterans generally abundant in both years throughout the study reach. In both years, oligochaetes (mainly tubificids) were generally the most abundant group at sites S21/22 and S7 which are downstream from the combined effluent discharges of L/E WWTP and Xcel, while also being abundant at site N45/46 in 2008. Turbellarians (flatworms) were also well represented at most sites in both years. The spring community was different than in fall and was dominated by the oligochaete Nais sp. at all six sites. This occurrence was undoubtedly due to accumulation of organic matter on the substrates that occurs over the winter low flow period in the SPR system. Dipterans were also predominant in the spring consisting mainly of midges. Mayflies and caddisflies were only occasionally abundant at some sites and were generally less numerous in the spring than in the fall, most likely because of their respective life histories (rather than any anthropogenic perturbations). The same mayfly and caddisfly taxa found in the fall were present in the spring. Amphipods (scuds) were abundant at site S84 only and generally not collected at any other site. Turbellarians, although present in the spring were considerably less numerous than found in the fall. The macroinvertebrate community structure in the rock basket samples was notably different from that collected in the spring and fall kick samples. The most notable difference was the scarcity of oligochaetes which was due to the lack of soft substrates in the rock baskets. Fewer mayflies and caddisflies were consistently collected; however chironomid abundance and numbers of taxa were slightly greater in the rock baskets than in the kick samples. The community structure of the rock basket samples was highly variable in that almost every site was dominated by a different major group with no apparent upstream/downstream trends evident.
The metrics most responsive to the main environmental stressors appeared to be the HBI, ICI, ICI/HBI ratio, % Oligochaeta, and % sprawlers. Relatively few EPT taxa were collected and there was so little variability among the sites to detect any impairment differences using this metric. In the fall of both sampling years, both the HBI and % Oligochaeta increased (worse) abruptly at sites S21/22 and S7 compared to the other sites indicating some impairment to the benthic community at these two sites. The ICI scores at these two sites also showed impairment as scores were either at or near their lowest (also worse) when compared to most of the other sites. The fall ICI scores were slightly more depressed in 2008 than in 2007 with the greatest decrease noted at site S76. Regardless of the lower ICIs, macroinvertebrate condition in the fall was rated as fair at all sites in both 2007 and 2008, except at site S76 which was rated as good in 2007. The ICI/HBI ratio appeared to better discriminate levels of impairment among sites than did either metric individually. Lower ICI/HBI ratios were recorded at sites
Aquatics Associates, Inc. vi May 2010 Aquatic Monitoring Program for SPCURE 2008
S21/22, S7, and N45/46 in both years as well as at sites N4 and N34 in 2008. The lowest ratios were noted at site S7. For site N45/46, the ICI/HBI ratio was comparatively lower in both years indicating that the benthic community at this site was more stressed than at most of the remaining sites. This site is located downstream from the largest storm drain in Denver that drains large industrial and residential areas. Shifting sand substrates are also predominant in this reach, which also negatively affect the macroinvertebrate community.
Metrics for the spring 2008 reflected the high abundances of the tolerant oligochaete, Nais sp. found at all the spring sites. Consequently, HBI values were notably higher and the ICIs and ICI/HBI ratios were lower than for both fall collections indicating that all sites were highly stressed by organic enrichment in the spring. The HBI was highest at site S21/22, and second highest at site N45/46 which further indicates that these two sites are more stressed than most of the other SPR sites. The spring ICIs and ICI/HBI ratios were also lowest at sites S21/22 and N45/46, with all ICI scores still in the fair category. The % Oligochaetes was relatively high at all sites in the spring although the substantial increases evident in fall at sites S21/22 and N45/46 were not as notable in the spring. The distribution of sprawlers was similar in the spring and fall with generally fewer sprawlers collected at site S30 and the remaining downstream sites.
Rock basket community metrics contradicted the results for the kick samples, especially at the presumably impacted sites S21/22 and N45/46. In contrast, the lowest HBI (best) for the rock baskets was reported at site S21/22 indicating that it was the least impacted rock basket site, while the HBI at site N45/46 though higher was still within the range of values reported for the other sites. The ICIs and the ICI/HBI ratios were highest (better) at both sites S21/22 and N45/46 which is also inconsistent with the kick results further indicating an apparently lower degree of impairment at these two sites. Instead, the metrics showed that site S84 was the most impaired as this site had fewest EPT taxa, the highest HBI, and lowest ICI due to the overwhelming abundance of tolerant amphipods. Furthermore, the comparatively lower ICI reported for site S76 was also contrary to the kick ICIs suggesting that this was one of the least impacted sites.
Aquatics Associates, Inc. vii May 2010 Aquatic Monitoring Program for SPCURE, 2008
1.0 INTRODUCTION
This report presents the initial sampling results of the biological monitoring program conducted by Aquatics Associates, Inc. (AAI) that began in the fall of 2007 for urban Segments 6c and 14 of the South Platte River (SPR) on behalf of the three major stakeholders which include Centennial Water and Sanitation District (CWSD), Littleton/Englewood Wastewater Treatment Plant (L/E WWTP), and Xcel Energy (Xcel a.k.a. Public Service Company of Colorado). The stakeholders are funding this bioassessment study through the South Platte Coalition for Urban River Evaluation (SPCURE) which is managing the project. This bioassessment study will be conducted over a period of six years (2007-2012) with sampling and reporting occurring on an annual basis. The SPR study area includes 13 sampling sites on the mainstem South Platte River and extends from below Chatfield Reservoir to approximately 0.5 mi. downstream from I-70 (Figure 1). Sampling sites were selected to represent reaches upstream and downstream from key discharge points (CWSD, L/E WWTP, and Xcel’s Arapahoe and Zuni Plants), major tributaries (Bear Creek and Cherry Creek), and major stormwater outfalls. Some sites were also selected to provide adequate spatial representation throughout the entire study reach. A list of study sites and locations is provided in Table 1 for the 13 sampling sites along with distances between sites and cumulative distances downstream from Chatfield Reservoir, downstream from L/E WWTP and Arapahoe Plant outfalls, and downstream from the confluence with Cherry Creek. Sampling frequency and types of samples collected at study sites are presented in Table 2 for the 2007-2008 monitoring period.
The purpose of this bioassessment (aquatic monitoring program) is to provide SPCURE with an evaluation of the existing biological integrity of SPR Segments 6c and 14 through a comprehensive study of the fish and macroinvertebrate communities. At the June 9, 2009 rulemaking hearing the Colorado Water Quality Control Commission (CWQCC) approved the CWSD proposal to combine SPR Segments 6c and 14 (CWQCC 2009a). The revised Segment 14 remains classified as Aquatic Life Warm 1. This bioassessment will also complement and enhance previous aquatic studies conducted by GEI Consultants, Inc. (GEI) for Segments 6 and 14, Denver Department of Environmental Health (DDEH), and ongoing studies by Metro Wastewater Reclamation District (Metro) for Segment 15. Specifically, the primary objectives of this study are to: • assess the overall and site-specific biological integrity and health of aquatic communities at key locations as compared to a reference site or condition; • provide aquatic life data to document temporal and spatial trends/changes that can also be compared to other assessments; and • develop a biological data base over the next five to six years that can be used to support appropriate water quality standards for Segments 6 and 14.
Aquatics Associates, Inc. 1 May 2010
Aquatic Monitoring Program for SPCURE, 2008
TABLE 1 BIOLOGICAL MONITORING SITES IN THE SOUTH PLATTE RIVER FOR SPCURE, 2007 AND 2008
Distance Cumulative Site Location Between Sites Distance
Distance from Chatfield Reservoir S84 0.5 mi. upstream from Marcy Gulch and Centennial WWTP outfall 0.6 mi. 0.6 mi. S76 Downstream from Mineral Ave. and Centennial WWTP, at Carson Nature Center 2.1 mi. 2.7 mi. S62 At Denver Seminary, upstream from Hudson Gardens 1.3 mi. 4.0 mi. S51 Upstream from Union Ave. and Bear Creek 2.3 mi. 6.7 mi. S34 Downstream from Hampden Ave. and Bear Creek 2.3 mi. 9.0 mi. S30 Downstream from Dartmouth Ave., upstream from Littleton-Englewood WWTP and Xcel’s Arapahoe Plant 0.4 mi. 9.4 mi.
Distance from L-E WWTP & Arapahoe outfalls S21/22 Upstream from Evans Ave., downstream from outfalls 0.4 mi. 0.4 mi. S7 Downstream from Mississippi Ave. and Sante Fe overpass, upstream from Xcel’s Zuni Plant 2.3 mi. 2.7 mi. N4 Upstream from 6th Ave. and Zuni Plant, downstream from Great Western plume 1.6 mi. 4.3 mi. N18 Downstream from I-25 overpass at Elitch’s, downstream from Zuni Plant 1.7 mi. 6.0 mi.
Distance from Cherry Creek confluence N28 0.25 mi. downstream from Cherry Creek confluence 0.25 mi. 0.25 mi. N34 Downstream from Park Ave. overpass, upstream from significant outfalls 0.9 mi. 1.3 mi. N45/46 Immediately upstream and downstream from I-70 overpass 1.3 mi. 2.6 mi. N47 ~0.5 mi. downstream from I-70, 0.75 mi. upstream from Burlington Ditch 1.3 mi. 3.9 mi.
Aquatics Associates, Inc. 3 May 2010 Aquatic Monitoring Program for SPCURE, 2008
TABLE 2 SAMPLING DATES AND TYPES OF SAMPLES COLLECTED AT SOUTH PLATTE RIVER SITES FOR SPCURE, 2007-2008 1/
2007 2008 Site fall spring fall
S84 M M F, M, RB S76 M M F, M, RB S62 M M S51 M F, M S34 M M S30 M M F, M, RB S21/22 M M F, M, RB S7 M M N4 M M N18 M M F, M, RB N28 M M N34 M F, M N45/46 M M M, RB N47 F
1/ Fish, macroinvertebrate, and rock basket sampling are denoted by F, M, and RB, respectively.
Aquatics Associates, Inc. 4 May 2010 Aquatic Monitoring Program for SPCURE, 2008
The aquatic monitoring program includes seasonal sampling of fish and macroinvertebrate communities with the spring and fall sampling events occurring during the low flow period in March and October/early November (Table 2). Fish sampling is only conducted in the fall, while macroinvertebrate sampling is performed in both the spring (secondary sampling) and fall (primary sampling) seasons. The fall macroinvertebrate sampling includes collections at all 13 sites using a kick net, whereas the spring sampling is conducted at only 6 of the sites. The macroinvertebrate program also includes, on a trial basis a fall artificial substrate sampling using rock baskets at the same six sites sampled in spring. The purpose of artificial substrate sampling is to provide a standardized substrate for macroinvertebrate colonization at the selected six sites in an effort to minimize substrate/habitat differences on community structure so that water quality effects can be more effectively evaluated. Fish sampling is performed at 8 of the 13 study sites, with 6 of these sites also the same as in spring. Sampling began in the fall 2007, however, only macroinvertebrate kick samples (primary sampling) were collected because the complete program had not yet been fully defined. The first full year of sampling was completed in 2008. Both the spring and rock basket macroinvertebrate sampling will be evaluated in the future when sufficient data are available to determine their long term usefulness in meeting the goals of this biomonitoring program.
Biomonitoring is an important component of water quality assessment programs because it has the potential to detect cumulative and chronic level impacts whereas water quality sampling only provides a snapshot of conditions at the time of sampling. Bioassessments can also detect physical effects on aquatic communities not associated with water quality such as those caused by channelization, widely fluctuating flows, substrate degradation, and other influences related to urbanization. Guidance for conducting bioassessment studies has been provided by the U.S. Environmental Protection Agency (EPA) with their protocols using reference sites for comparison to study sites for determining relative degrees of site impairment (Barbour et al. 1999). Use of EPA’s reference site concept for the evaluation of the urban SPR, however is difficult if not impossible to accomplish due to the lack of “pristine” or “minimally degraded” reference sites in the same or comparable drainages. Furthermore, Sprague et al. (2006) concluded that historically, aquatic communities may have been altered prior to any significant urbanization by the development of early agricultural and water management practices. Therefore, a reference condition defined as a “constructed” reference site, which is similar to the approach used by DDEH (2005), will be used for the macroinvertebrate bioassessment component of this study. A “reference site” will be constructed using the best score for each of the selected site-specific core community metrics and will be used to evaluate the relative impairment at each of the SPR sites. This approach is described in more detail in the methods section of this report. This report however does not contain the results of a “constructed” reference site condition analysis, as this analysis will be provided in
Aquatics Associates, Inc. 5 May 2010 Aquatic Monitoring Program for SPCURE, 2008 a later report once sufficient macroinvertebrate data have been collected and analyzed. The macroinvertebrate results presented herein include density, number of taxa, percent relative abundance, and various other community parameters for the data collected to date.
Concurrent with the fall 2008 fish sampling event, fish from selected trophic levels (omnivore/bottom, omnivore/water column, insectivore, and piscivore) were collected for mercury and selenium analyses. The EPA is currently evaluating the toxicity of selenium in surface waters for the purpose of establishing appropriate water quality standards for the State and developing selenium criteria. According to the CWQCD (2009), the EPA is expected to publish draft water quality criteria for selenium in the near future and the current mercury aquatic life chronic standard of 0.77 TVS (fish) is under review to modify the calculation formula to account for bioaccumulation rather than dose-response. The EPA is also using mercury data to evaluate the feasibility of establishing a fish tissue standard vs. the current water column standard.
The selenium fish tissue results are intended to support Xcel’s proposal on behalf of the SPCURE stakeholders to the CWQCC to support the resolution of the temporary standard modification to the Basic Standards for selenium, because of the significant uncertainty concerning the long term underlying selenium standard of 4.6 ug/L. Xcel is collecting additional water and fish selenium data to determine the source of upstream selenium and to propose a standard that would be protective of the aquatic life use in Segment 14 (CWQCC 2009b). The CWQCC plans to adopt a selenium temporary modification of “current condition” which will be proposed at the Commission’s rulemaking hearing on June 8-9, 2009. In addition, the selenium results for the SPCURE bioassessment are intended to further support the premise that despite elevated water and fish tissue concentrations (greater than EPA and other researcher recommended criteria), many fish populations have not shown detrimental effects due to elevated selenium.
Results of the 2008 fish tissue analyses for mercury and selenium are presented in this report. The mercury discussion is brief as concentrations in almost all samples were less than method detection limits. Selenium, on the other hand, was detected in the fish tissue samples and concentrations are discussed for the different species collected, spatial trends, with comparisons made to other applicable studies. Fish selenium concentrations are further compared to fish tissue criteria recommended by the EPA and other researchers. The predominant chemical form of selenium likely found in the SPR and its relative toxicity is also discussed.
Aquatics Associates, Inc. 6 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Temperature in Colorado water bodies is a current water quality standards issue. The CWQCD proposes to classify Segment 14 as Aquatic Life Warm 1 with a temperature standard of Water Stream Tier I, which is protective of the johnny darter that is found in this Segment (CWQCC 2009c). L/E WWTP in cooperation with Xcel and other members of the SPCURE, proposes to change the temperature standard from Tier I to Tier II, and to adjust the seasonality of the temperature criteria as follows: change warm water time frame from March 1-November 30 to February 9-December 20 (chronic: 27.5oC, acute: 28.6oC) and cold water season from December 1-February 29 to December 21-February 8 (chronic: 13.7oC, acute: 14.3oC) (CWQCC 2009d). The proposed criteria changes will be addressed at the CWQCC rulemaking hearing on June 8-9, 2009. Fish population results will be considered in the proposed temperature criteria modifications.
Aquatics Associates, Inc. 7 May 2010 Aquatic Monitoring Program for SPCURE, 2008
2.0 METHODS
2.1 SITE CHARACTERISTICS
Observations of general site characteristics and stream conditions were made concurrent with the biological sampling events. Observations of water clarity, substrate and flow conditions, the presence and relative amounts of algae and/or macrophytes, and other notable site conditions were recorded at the time of sampling. Photographs of study sites were also taken to further document stream conditions encountered on sampling occasions. These observations are only meant to document seasonal and year to year changes in site conditions as they relate to the aquatic communities sampled. The detailed habitat assessment performed by GEI in the fall of 2008 was intended to more fully support the biological assessment for SPCURE.
2.2 FISH POPULATIONS
2.2.1 Sampling and Analysis
Fish populations were sampled at the eight study locations during the low flow period in the fall. Shoreline electroshocking equipment with one stationary negative and seven mobile positive electrodes were used to effectively sample sites in the South Platte River study area. Fish were collected using two- pass removal techniques. Fish were collected in two consecutive passes with fish from each pass kept separate for processing. All fish captured were identified, counted, measured, and released to the stream unharmed, except for fish specimens that were retained for the mercury and selenium tissue analyses. For each species, lengths and weights were measured for all individuals collected. When a large number of a single species was collected, specimens were counted and weighed collectively after a representative sample of individual fish was measured. Individuals were visually examined and the incidence of disease was recorded. The level of disease severity was also rated on a scale of 0 to 3, with ratings of 0, 1, 2, or 3 denoting either no, slight, moderate, or heavy disease levels recorded for individuals examined (AAI 2007).
Fish sampling areas were representative of the stream reach and were of sufficient length to include all macro-habitats (riffle, run, pool) present. In most cases, natural physical barriers (very shallow depths over the riffle) prevented fish from moving into or out of the study reach, and block nets were used where such upstream physical barriers were not present. Study site boundaries were permanently marked with rebar. The length of study areas ranged from approximately 267 to 320 meters (875 to 1,050 feet) at the
Aquatics Associates, Inc. 8 May 2010 Aquatic Monitoring Program for SPCURE, 2008
SPR sites. Stream widths were measured at 15-meter intervals throughout each study section. Average stream widths ranged from approximately 17 to 27 meters (56 to 89 feet) at the SPR sites. Average stream width and total station length were used to calculate the total area sampled.
A list of fish species collected including mean lengths and weights, relative abundance, and percent disease were calculated for all study sites. The Index of Biotic Integrity (IBI) was also calculated for the population at each site based on the methods outlined in Karr (1981), Karr et al. (1986), Schrader (1989), and EPA Rapid Bioassessment Protocols (Barbour et al. 1999, Plafkin et al. 1989). The EPA has developed different sets of metrics that are specific for the various regions of North America based on the original IBI developed by Karr (1981), which provides a consistent assessment methodology for analyzing fish assemblage data. The final list of metrics developed specifically to assess fish data from the SPR sites was based on metrics suggested by Schrader (1989) and Barbour et al. (1999) for Colorado Front Range streams. The eleven metrics incorporated in IBI analysis include: 1) total number species, 2) number of darter species, 3) number of sunfish species, 4) number of minnow species, 5) number of intolerant species, 6) percent white suckers, 7) percent omnivores, 8) percent specialized insectivores, 9) total number of individuals collected, 10) percent introduced species, and 11) percent diseased individuals. Each metric value was calculated and scored based on the data collected. Metric values approximating, deviating slightly from, or deviating greatly from values for reference sites are scored as 5, 3, or 1, respectively. Species tolerance and trophic designations used in the IBI analysis are defined in Barbour et al. (1999). Site-specific fish abundance data for the 2008 sampling period were used to determine scoring ranges for the total number of individuals metric. This metric will be recalculated and updated after each year of fish sampling as appropriate. The final IBI scores calculated for each site are the sum of the eleven individual metric scores. Final IBI scores may range from 11 to 55, with higher scores indicating better community condition. Integrity categories and their corresponding numerical ranges were determined by modifying the numerical ranges provided in Karr (1981) and Plafkin et al. (1989). IBI score ranges and corresponding condition categories for the SPR fish data are: excellent (53- 55), good (44-52), fair (37-43), poor (29-36), and very poor (11-28) as calculated according to EPA guidance documents (Barbour et al. 1999, Plafkin et al. 1989).
The IBI condition categories defined by the EPA should not be interpreted as comparative of some pristine or reference condition, but rather as general descriptors for the lower to higher scoring sites. Furthermore, it is important to note that the fish IBI as originally developed by Karr (1981) was for assessing degradation in mesic midwestern streams that are relatively rich in fish fauna, and furthermore, recent literature by Bramblett and Fausch (1991) and Bramblett et al. (2005) caution against a strict interpretation of fish IBI scores and respective condition categories when assessing western Great Plains
Aquatics Associates, Inc. 9 May 2010 Aquatic Monitoring Program for SPCURE, 2008 streams, which comparatively are depauperate in fish fauna and those species present are largely habitat generalists. Because of these limitations, which are the most recent research on the applicability of the IBI to western Great Plains streams, the SPR fish IBI scores (rather than the condition categories) will be used as a point of reference for monitoring changes in the fish community at and among the study sites over time.
2.2.2 Mercury and Selenium Fish Tissue Study
Fish specimens for whole body mercury and selenium analyses were collected concurrent with the fall population surveys at the eight fish sampling sites. The purpose of this 5-year study (2008-2012) is to provide an assessment of the mercury (Hg) and selenium (Se) whole body concentrations in fish in SPR Segment 14 as it flows through metropolitan Denver with the original sampling design intended to be consistent with that of Metro for Segment 15. The resulting data base for mercury and selenium in fish tissue will be used to support the establishment of appropriate water quality standards.
The study included both base level and higher trophic level analyses. The base level program included analysis of selected omnivore and insectivore species. Two bottom feeding omnivores and one water column omnivore were selected with the bottom feeders consisting of white suckers (Catostomus commersoni) and carp (Cyprinus carpio) and the water column species being the fathead minnow (Pimephales promelas). The bottom insectivore species was the longnose dace (Rhinichthys cataractae). The higher trophic level program included analysis of the piscivore species smallmouth bass (Micropterus dolomieu) and/or largemouth bass (Micropterus salmoides). At sites where the target species were not available, species substitutions were made using green sunfish (Lepomis cyanellus) as a water column omnivore and the creek chub (Semotilus atromaculatus) as a bottom omnivore.
Fish were composited into one sample for each of the species analyzed. Each composite sample included at least three individuals (when available) of similar size for each fish species, except for fathead minnows which included 15-20 individuals in order to obtain at least 20 grams of tissue (wet weight) that is required to achieve the laboratory method detection limits. Specimens of similar size were selected to provide uniformity in length/age (time of exposure) among sites, as well as provide a basis for future study comparisons.
Fish specimens were handled using sterile surgical gloves to prevent cross contamination between species and among the different sites. The fish were placed in Ziplock freezer bags, double bagged, labeled, placed on ice, and transported to AAI’s facility in Fort Collins where the samples were stored in a freezer
Aquatics Associates, Inc. 10 May 2010 Aquatic Monitoring Program for SPCURE, 2008 after each sampling day. After all sampling was completed, samples were delivered in one shipment to ACZ Laboratories, Inc. in Steamboat Springs, CO. Samples were delivered to the lab in coolers containing dry ice with full chain-of-custody procedures being followed. In the laboratory, each individual sample was thawed and blended using a laboratory grade blender. A sufficient sample aliquot was taken from each blended composite and weighed before acid extraction. Sample extracts for selenium were analyzed by ICP-MS by EPA method M6020, and mercury was analyzed by EPA method M7471A CVAA (Cold Vapor Atomic Absorption Spectophotometry). Lab results were expressed in ug/g (ppm) as wet weight. In order to compare the wet weight values with literature values that are usually expressed as dry weight, a conversion factor was applied to the reported values. Most fish tissue contains between 18.7% and 23.3 % dry matter (Brinkman 2004); consequently, an approximate mid- range value of 20% dry matter was chosen for conversion to dry weight, which provides the factor of 5X (1.0/0.20 = 5).
The mercury and selenium results were summarized by site for each of the species selected based on their trophic and habit behaviors. Mean concentrations were calculated for each species and site to evaluate spatial trends and concentrations among the species analyzed. Data were also compared with other streams in the SPR and other relevant drainages, as well as to fish tissue criteria recommended by the EPA and other researchers.
2.3 MACROINVERTEBRATES
Macroinvertebrate sampling was conducted at all 13 sites in the fall (primary sampling), while the spring collections (secondary sampling) were performed at only 6 of the sites (Table 2). Sampling was performed using a kick net according to methods outlined by Klemm et al. (1990), the Colorado Water Quality Forum (1995), and DDEH (2005). Benthic macroinvertebrates were collected from riffle and glide habitats, which are the two predominant habitat types in SPR Segment 14, using a kick net with a mesh size of 425 microns (um). Glides are run habitats with substrates consisting of silt, sand, and gravel with some small cobble (<2.5”), whereas riffles typically have a mix of substrates and generally larger cobble. Each riffle and glide sample included six kick net samples that were combined into one composite sample for analysis with the total area sampled being approximately one square meter (1 m2). Each sampling event included the collection of additional samples for QA/QC purposes (10%). The fall sampling included three additional QA/QC samples for a total of 29 samples collected, whereas the spring sampling included one additional QA/QC sample resulting in a total of 13 samples.
Aquatics Associates, Inc. 11 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Artificial substrate sampling using rock baskets (RB) was also conducted in the fall at the same six sites that are sampled in the spring. Rock basket samplers were installed at each site for at least a 4-week colonization period, and samplers were retrieved concurrent with the kick sampling event in fall. Rock basket samplers were cylindrical wire barbeque baskets (7” diameter x 11” length) that were filled with a mixture of cobble ranging from 1-3” in size (2.5-8.0 cm) (Klemm et al. 1990, Rosenberg and Resh 1982). Each RB sampler provides a rock surface area of approximately 0.3 m2 for colonization. Three RB samplers were installed at each site in glide habitat, which were combined into one composite sample for analysis with a total sampling area of 1 m2. Rock baskets were retrieved by placing a kick net immediately downstream to collect the sampler and any escaping invertebrates. Baskets were opened, and the contents were placed into a 5-gallon bucket. The cobbles were hand washed and scrubbed of all organic material and macroinvertebrates.
For both kick and RB samples, the composited material collected was carefully elutriated in the field to remove excess debris and inorganic material before being placed into labeled sample containers and preserved with 10% formalin. Samples were transported to the AAI laboratory for analysis.
Identification of macroinvertebrates and laboratory techniques were performed according to the methods outlined in Klemm et al. (1990). In the laboratory, samples were thoroughly rinsed of excess preservative and debris in a 500 um sieve before being placed in a white tray for processing. All macroinvertebrates were removed from the debris with forceps and placed in labeled vials filled with 80% ethanol. Macroinvertebrates were identified to the lowest taxonomic level possible with the aid of both binocular dissecting and compound microscopes using appropriate taxonomic literature. A macroinvertebrate reference collection was prepared which contains representative specimens of each taxon that are preserved in vials of 80% ethanol or on permanent slide mounts with Euparal or PVA (polyvinyl alcohol) when necessary. Any new taxa encountered in subsequent years will be added to the reference collection for the SPCURE project.
Following identification and enumeration, a species list including the number of organisms collected, total density, total number of taxa, relative abundance, and species diversity were calculated for each sample. Data for the riffle and glide samples were combined for all macroinvertebrate community analyses.
Community parameters selected for establishing the “constructed” reference condition were also calculated which include (but may not be limited to) the following core metrics: 1) taxa richness, 2) EPT taxa (number of Ephemeroptera and Trichoptera taxa; Plecoptera taxa are not expected to be found), 3)
Aquatics Associates, Inc. 12 May 2010 Aquatic Monitoring Program for SPCURE, 2008 percent dominant taxon, 4) HBI (Hilsenhoff Biotic Index), 5) percent Diptera, 6) percent Oligochaeta (high numbers of oligochaetes usually indicate increased concentrations of nutrients), 7) percent sprawlers (Sprawlers are those insects that live on sand, silt, or clay. Their bodies are flattened and their legs extend out so they can maintain their bodies on top of the sand and not sink below (Plafkin et al. 1999). For example, in the SPR study area sprawlers were represented by one mayfly, one caddisfly, and numerous chironomids and a few other dipterans), and 8) percent Chironomidae that are Chironomus or Cricotopus. Tolerance values used in the HBI incorporate values presented by Barbour et al. (1999) with other references occasionally used as needed. The HBI measures macroinvertebrate community responses to organic pollution. HBI values may range from 0 to 10, with higher values (generally >6) indicating higher degrees of organic pollution. Macroinvertebrate communities with high percentages of tolerant organisms will result in an elevated HBI score which indicates the presence of some level of stress due to organics. These eight core community metrics were chosen based on recommendations in Development of Biological Assessment Tools for Colorado prepared for the CWQCD (Paul et al. 2005) and other metrics discussed by DDEH (2005).
A reference site will be constructed using the best score for each of the selected site-specific core community metrics and will be used to evaluate the relative impairment and health at each of the SPR sites. The “constructed” reference site condition analysis will be performed separately for the fall, spring, and rock basket samples. Individual core metric scores will be determined using box-plots based on calculations of the median and 15th and 85th percentiles. Additionally, the +/- one standard deviation (sd) will also be calculated and will be used to determine the maximum/minimum scores for each core metric data set. The 85th and 15th percentile values on either side of the median will be used to determine intermediate scores (e.g., for the EPT metric, the data point corresponding to the plus one sd will be the maximum score for this metric and would be assigned the maximum score of 8, while a minimum EPT (minus one sd) would have a score of 2; the median/85th percentile would have a score of 6, while the median/15th percentile would have a score of 4). Once sufficient data have been collected, a “constructed” reference condition will be defined and used to determine the relative degrees of impairment as outlined for the Rapid Bioassessment Protocol III (RBP) analysis (Barbour et al. 1999, Plafkin et al. 1989). The RBP analysis provides a standardized method for evaluating spatial, seasonal, and annual differences. RBP score ranges and corresponding condition categories are: nonimpaired (>83%), slightly impaired (54-79%), moderately impaired (21-50%), and severely impaired (<17%) (Plafkin et al. 1989). The assessment of impairment using the “constructed” reference condition analysis will be presented in a later report when sufficient data have been collected and analyzed.
Aquatics Associates, Inc. 13 May 2010 Aquatic Monitoring Program for SPCURE, 2008
The Invertebrate Community Index (ICI) was also included in the evaluation of macroinvertebrate data to provide an additional objective measure of biological condition/integrity for the SPR study sites. The ICI values were calculated according to methods outlined by DeShon (1995), which provide the detailed methodology used by the Ohio EPA for assessing the biological condition of streams in Ohio and the surrounding region. The ICI analysis involves the scoring of ten different metrics with the sum of these metrics providing the final index score. The metrics used include: 1) total number of taxa, 2) number of mayfly taxa, 3) number of caddisfly taxa, 4) number of dipteran taxa, 5) percent mayflies, 6) percent caddisflies, 7) percent of tribe Tanytarsini midges, 8) percent other dipteran and non-insects, 9) percent tolerant organisms, and 10) number of qualitative EPT taxa. Each of these metrics is given a score of 6, 4, 2, or 0 depending on the value derived from macroinvertebrate data for each station. For tolerant species designations, any species with an HBI tolerance value of 8-10 was considered tolerant. Individual metric scores were determined by comparing derived values with species area plots for the reference data versus drainage area. A score of 6 for a given metric indicates the metric value is within the range exhibited by very good or exceptional aquatic communities, a score of 4 indicates that the value is characteristic of more typical or good communities, a score of 2 indicates the value is moderately deviating from the expected range of good to exceptional values, and a score of 0 indicates the value is strongly deviating from expected good or exceptional values. Final ICI scores were calculated for each site, and may range from 0 to 60 with higher ICI scores indicating better community condition. Corresponding benthic community condition ratings developed for the ICI are: exceptional (46-60), good (36-45), fair (13-35), and poor (0-12) (DeShon 1995). The ICI/HBI ratio was also calculated to further aid in discerning relative degrees of impairment between the SPR study sites. Generally, there should be an inverse correlation between the HBI and ICI metrics (i.e., if the HBI is high the ICI should be low and visa versa). If both are high or low, then this anomalous result would trigger a more in depth analysis of the community at a particular site.
Aquatics Associates, Inc. 14 May 2010 Aquatic Monitoring Program for SPCURE, 2008
3.0 RESULTS
3.1 SITE CHARACTERISTICS
Observations of general site characteristics and the conditions at the time of sampling were made concurrent with the biological sampling events. Notable conditions are summarized below. Photographs of study sites taken at the time of sampling are presented in Appendix A.
During the fall 2007 and the spring and fall 2008 sampling events, stream conditions were optimum for both macroinvertebrate and fish sampling. Stream flows were low and the water was generally clear. On one particular occasion during the 2008 fish sampling event, a slight increase in turbidity was evident at site S21/22 early in the day due to a storm event and subsequent runoff that occurred the previous night, although these conditions did not noticeably reduce sampling effectiveness.
Substrates in the riffle habitats consisted mainly of gravel and small to medium cobble with large cobble abundant at some sites. Smaller substrates became more predominant when progressing downstream as the relative amounts of silt, sand, and gravel generally increased in the riffle habitats. Substrates in the run habitats (glides) were relatively similar upstream to downstream with substrate composition varying less than in the riffles.
Attached filamentous algae (periphyton) growth varied somewhat among the sites as noted during the spring and fall events. In the fall, slight to moderate growth of green filamentous algae was present at all sites in both 2007 and 2008. However, algal growth increased noticeably in the downstream portion of the study area from site N18 downstream to site N45/46 (from I-25 overpass/Elitch’s to I-70), where the cobble substrates were covered sporadically by long stringy green filamentous algae and similar amounts of growth were observed at all four sites (i.e., sites N18, N28, N34, and N45/46). Small amounts of green filamentous algae were also observed at all sites during the spring event; however algae growth was only dense in the riffles at site S76 downstream from Mineral Ave. and Marcy Gulch. Water clarity was also slightly reduced at this site due to suspended organic material which was more abundant than observed at any of the other sites. Organic material generally tends to accumulate on the substrates during the fall/winter low flow period until it is scoured away by the increased flows due to releases from Chatfield Reservoir.
During the fall 2008 fish sampling event, dense growth of rooted aquatic vegetation was observed at site S84 in the shallow pool habitats that remained after releases from Chatfield Reservoir were shut off for
Aquatics Associates, Inc. 15 May 2010 Aquatic Monitoring Program for SPCURE, 2008 the season. The macrophytes were mainly sago pondweed (Potamogeton pectinatus) with some waterweed (Elodea sp.) and water buttercup (Ranunculus sp.) also noted. Small isolated patches of pondweed were also observed in backwater areas at site S76; otherwise macrophyte growth was not observed at any of the other sites.
3.2 FISH
Fish monitoring was conducted for the first time in the fall 2008 which included the population survey and concurrent collections of fish for mercury and selenium tissue analyses at the eight fish sites (Table 2). Survey results including percent abundance, total number and species of fish collected, number of native species, and the Index of Biotic Integrity (IBI) scores at sites in the South Platte River are presented in Table 3. Percent relative abundance of numerically dominant and important native fish species collected in 2008 is presented in Figure 2. Comparisons of the total numbers of fish collected and numbers of native vs. non-native species are provided in Figure 3. The fish IBI scores for the eight sites are depicted in Figure 4. A list of species collected (scientific and common names) and their native or non-native status, and tables including the total numbers and species collected and percent composition at each site are presented in Appendix B. The fish population, mercury and selenium analytical results, and summary are discussed separately in Sections 3.2.1, 3.2.2, and 3.2.3, respectively.
3.2.1 Populations
The fish community in SPR Segments 6 and 14 was typical of Colorado transition-zone streams that are highly influenced by the affects of urbanization, primarily widely fluctuating flows. Other researchers also have linked other specific urbanization stressors as influential on fish communities in the SPR Basin although such intensive evaluations (correlations) are not within the scope of this study (Sprague et al. 2006, and Zuellig et al. 2007). Species composition in the study area was comparable to the historical records for fish species distribution and abundance in streams in the South Platte River drainage (Beckman 1952, Nessler et al. 1997, Propst 1982, Woodling 1985, 1996, Zuellig 2001). In 2008, 10 of the 22 total species collected were native to the SPR drainage (Table 3). Except for the Iowa darter (Etheostoma exile) collected at site S76 only, which is uncommon in the SPR drainage, all other native species collected (excluding the gizzard shad) are considered either abundant or common according to the last inventory of native fishes conducted by the CDOW (1992-1994) (Nessler et al. 1997). The fewest number of native species collected was three at site S84 while the highest number collected was eight at site N34 (Table 3). Otherwise, six or seven native species were collected at the other sites. Overall, the total number of species (native and non-native) collected ranged between 8 and 16 at individual sites,
Aquatics Associates, Inc. 16 May 2010 Aquatic Monitoring Program for SPCURE, 2008
TABLE 3 PERCENT ABUNDANCE OF FISH SPECIES, TOTAL COLLECTED, NUMBER OF NATIVE SPECIES, AND INDEX OF BIOTIC INTEGRITY (IBI) SCORES AT SOUTH PLATTE RIVER SITES, FALL 2008
STUDY SITES SPECIES S84 S76 S51 S30 S21/22 N18 N34 N47
White Sucker 99.3 77.0 79.3 81.4 70.7 25.1 12.4 26.2 Longnose Sucker 0.4 0.2 1.7 0.4 Longnose Dace 0.1 0.8 7.1 2.1 7.3 0.2 51.6 3.5 Creek Chub 0.2 5.7 9.3 5.9 27.4 5.9 4.8 Fathead Minnow 6.2 2.0 4.2 38.2 22.2 58.8 Common Carp 0.2 0.6 2.6 3.6 Golden Shiner 0.1 0.3 Green Sunfish 6.6 0.2 0.5 4.2 0.5 0.2 0.1 Smallmouth Bass <0.1 6.5 1.1 2.7 2.2 1.1 0.5 0.4 Largemouth Bass 0.4 2.7 0.2 0.4 3.6 1.0 0.9 0.5 Bluegill 0.1 0.1 Black Crappie <0.1 0.1 0.2 0.1 <0.1 Johnny Darter 0.1 1.1 1.4 5.8 1.1 1.0 Iowa Darter 4.7 Yellow Perch 0.1 0.5 Walleye 0.2 0.1 Brook Stickleback <0.1 0.2 0.1 Gizzard Shad 0.1 Mosquitofish <0.1 Rainbow Trout <0.1 0.8 Rainbow x Cutthroat Hybrid <0.1 Brown Trout 0.3
TOTAL COLLECTED 4683 1332 2124 1117 358 1764 1755 2004 TOTAL SPECIES 8 11 9 12 9 11 16 13 NATIVE SPECIES 37676787 IBI SCORE 29 27 31 33 25 35 45 39
* Bold indicates native to South Platte River.
Aquatics Associates, Inc. 17 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 2 PERCENT RELATIVE ABUNDANCE OF NUMERICALLY DOMINANT AND IMPORTANT NATIVE FISH SPECIES COLLECTED AT SOUTH PLATTE RIVER SITES, FALL 2008
2008 40 White Sucker 30 20 10 0
40 Longnose Sucker 30 20 10 0 40 Longnose Dace 30 20 10 0 40 Creek Chub 30 20 10 0 40 Fathead Minnow 30 20 10 0 40 Green Sunfish PERCENT RELATIVE ABUNDANCE 30 20 10 0 40 Johnny Darter 30 20 10 0 40 Iowa Darter 30 20 10 0 S84 S76 S51 S30 S21/22 N18 N34 N47
STUDY SITE
Upstream Downstream
Aquatics Associates, Inc. 18 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 3 COMPARISONS OF NUMBERS OF FISH AND NATIVE VS. NON-NATIVE SPECIES COLLECTED AT SOUTH PLATTE RIVER SITES, 2008
2008
4500 4000 3500 3000 2500 2000 1500 1000 500 NUMBER COLLECTED 0 S84 S76 S51 S30 S21/22 N18 N34 N47
Native Non-native 16 14 12 10 8 6 4 2 SPECIES COLLECTED SPECIES 0 S84 S76 S51 S30 S21/22 N18 N34 N47
STUDY SITE
Upstream Downstream
Aquatics Associates, Inc. 19 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 4
FISH INDEX OF BIOTIC INTEGRITY (IBI) FOR SOUTH PLATTE RIVER SITES, 2008
IBI - 2008
50
40
30
20
10 FISH IBI SCORES FISH 0 S84 S76 S51 S30 S21/22 N18 N34 N47
STUDY SITE Upstream Downstream
Aquatics Associates, Inc. 20 May 2010 Aquatic Monitoring Program for SPCURE, 2008
TABLE 4
WHOLE BODY SELENIUM CONCENTRATIONS IN SELECTED FISH SPECIES FROM SOUTH PLATTE RIVER SITES, FALL 2008
Selenium Results (u g/g, dry wt.) 1/ Site WHS 2/ CPP/CRC FMW/SNF LND SMB/LMB Site Mean o/b 3/ o/b o/wc i/b p S84 1.8 -- -- 1.9 4.4 4/ 2.7 S76 2.2 -- 5.0 5/ 4.3 2.3 3.5 S51 2.3 -- 4.5 5.8 3.5 4.0 S30 3.0 7.3 5.1 8.7 4.5 5.7 S21/22 3.2 10.5 4.4 10.0 5.4 6.7 N18 4.8 5.5 6/ 5.8 10.2 5.6 6.4 N34 5.8 7.1 5.3 9.0 6.2 6.7 N47 5.6 4.3 6.3 14.5 4.8 7.1
Mean 3.6 6.9 5.2 8.1 4.6 Range 1.8-5.8 4.3-10.5 4.4-6.3 1.9-14.5 2.3-6.2
1/ u g/g = ppm (micrograms per gram = parts per million). Recommended criteria are 7.9 ppm and 9.0 ppm (EPA 2004, DeForest 1999). 2/ Abbrevations for fish species are: white suckers (WHS), common carp (CPP), creek chub (CRC), fathead minnow (FMW), green sunfish (SNF), longnose dace (LND), smallmouth bass (SMB), and largemouth bass (LMB). 3/ Abbreviations for trophic and habit designations are: omnivore/bottom (o/b), omnivore/water column (o/wc), insectivore/bottom (i/b), and piscivore (p). 4/ Concentration for largemouth bass. 5/ Concentration for green sunfish. 6/ Concentration for creek chub.
Aquatics Associates, Inc. 21 May 2010 Aquatic Monitoring Program for SPCURE, 2008
TABLE 5
COMPARISONS OF SELENIUM CONCENTRATIONS IN FISH FOR THE SOUTH PLATTE RIVER, SPCURE 2008 VS. DATA REPORTED FOR SIMILAR STREAMS
Selenium Results (u g/g, dry wt.) 1/ Species SPR 2/ SPR Tribs. 3/ Big Dry Creek 4/ Republican R. 5/ Solomon R. 6/ Fathead Minnow 5.2 (4.4-6.3) 3.2-19.4 11.7 (7.5-15.5) 7.88 -- Longnose Dace 8.1 (1.9-14.5) -- 13.3 (8.5-17.0) -- -- White Sucker 3.6 (1.8-5.8) -- -- 9.56 -- Common Carp 6.9 (4.3-10.5) -- -- 6.68 7.8-10.4 SM Bass/LM Bass 4.6 (2.3-6.2) -- -- 8.44 -- Red Shiner ------5.8-10.0 1/ u g/g = ppm (micrograms per gram = parts per million). 2/ Data collected by AAI in 2008 for South Platte River, SPCURE project. 3/ Data for various South Platte River tributaries (Brown & Caldwell 2003). 4/ Data for Big Dry Creek in 2004 (north of Denver, Standley Lake to Wattenberg) (Aquatics Associates, Inc. 2005). 5/ Data for Republican River (May et al. 2001). 6/ Data for Solomon River in north central Kansas (May et al. 2008).
Aquatics Associates, Inc. 22 May 2010 Aquatic Monitoring Program for SPCURE, 2008 with the most species found at site N34 where native and non-natives were equally represented (Table 3, Figure 3). The fewest total species (eight) were found at site S84 immediately downstream from Chatfield Reservoir. Total numbers of fish were relatively high ranging from 1,117 to 4,683 fish at individual sites except at site S21/22 where only 358 were collected. The highest number of fish collected was at site S84 due to the overwhelming abundance of young suckers (<100 mm) captured in the somewhat isolated and densely vegetated pool habitats encountered in the fall.
The fish community in the SPR study area in 2008 was dominated by species from the sucker (Catostomidae) and minnow (Cyprinidae) families as found in other studies (GEI 2008, Nessler et al. 1997, Woodling 1996, Zuellig 2001). White suckers (Catostomus commersoni) were by far the most abundant species collected at sites S84 through S21/22 (reach from Chatfield Reservoir to Evans Ave.) where sucker abundance ranged from 70.7% (site S21/22) to 99.3% (site S84) (Table 3, Figure 2). In this reach, 4,650 suckers were collected at site S84 compared to 253 to 1,684 collected at sites S21/22 and S51, respectively (Appendix B). White suckers were also numerous at sites N18, N34, and N47 (217 to 526 fish) but were not the dominant species at these locations. The fathead minnow was collected at six of the eight sites and was the dominant species at sites N18 (38.2%) and N47 (58.8%). Their abundance increased dramatically at sites N18 through N47 (three farthest downstream sites) compared to sites upstream. Fathead minnows represented 22.2 to 58.8% of the population at these sites with 390 to 1,178 individuals collected (vs. only 15 to 131 fish upstream) (Appendix B). The longnose dace (Rhinichthys cataractae), a sensitive insectivore (Barbour et al. 1999), was found at all sites and overall was the third most abundant species collected. Longnose dace was the dominant species only at site N34 where they comprised 51.6% of the population and 906 individuals were collected. These dace were also numerous at sites S51 and N47 (151 and 71 fish, respectively), with comparatively fewer collected at the rest of the sites (4 to 26 fish). Longnose dace were likely more abundant at site N34 due to the preponderance of suitable riffle habitat that is preferred by this species. Creek chubs (Semotilus atromaculatus) were also abundant and found at seven of the eight sites, although they were only numerous at five sites (S51, S30, N18, N34, and N47). Creek chubs were most abundant at site N18 where 484 individuals were collected (27.4%). At the other sites where they were numerous, 97 to 122 individuals were collected (4.8 to 9.3%).
Of the species collected in 2008, the Iowa darter is the only State listed species of special concern (not a statutory category) (CDOW 2007). The Iowa darter was only found at site S76 where 62 individuals were captured. While johnny darters (Etheostoma nigrum) were not collected at either site S76 or S84, they were found at all of the remaining downstream sites. The johnny darter was most abundant at site N18 with 103 individuals collected, while they were less abundant at the other sites (2 to 20 individuals). In
Aquatics Associates, Inc. 23 May 2010 Aquatic Monitoring Program for SPCURE, 2008 comparison, GEI collected only two Iowa daters in their fall 2005 synoptic study, one each at sites S84 and S62 (upstream from Marcy Gulch and upstream from Hudson Gardens) and no johnny darters were captured at any of the sites sampled in Segments 6 and 14 (GEI 2008). The johnny darters collected by AAI in 2008 were consistently found in run habitats with sand substrates (typically away from the banks) and relatively slow velocities. Furthermore, the fact that more darters (and more fish overall) were collected during this study is largely due to the more intensive sampling methods employed by AAI (two- pass removal, bank shocking equipment) than those used by GEI which were based on different project objectives (i.e., seining main channel, backpack shocking along margins). For example, 22 species and 358 to 4,683 total fish were collected in 2008 vs. 16 species and 57 to 1883 individuals collected by GEI in 2005.
The centrarchids were mainly comprised of the native green sunfish and non-native bass and were collected at all sites in varying numbers, except for the green sunfish (Lepomis cyanellus) which was not captured at site S84. Green sunfish were most numerous (88 individuals) at site S76, whereas fewer were collected downstream ranging from only 2 to 15 individuals. Smallmouth bass (Micropterus dolomieu) were also most abundant at site S76 with 86 individuals collected and they remained moderately abundant at the sites downstream with 8 to 30 individuals collected. At site S84 only one smallmouth bass was collected compared to 21 largemouth bass (Micropterus salmoides). Smallmouth bass appear to be well established in areas where rocky substrates are present along the stream banks. Largemouth bass were also relatively numerous at site S76 where 36 individuals were collected, while at sites downstream their numbers decreased somewhat and ranged from 5 to 18 individuals.
The common carp (Cyprinus carpio) was collected at four sites including S30, S21/22, N34, and N47. Only two individuals each were collected at sites S30 and S21/22, with 46 at site N34 and 73 at site N47. The carp captured at sites S30 and S21/22 were large (>25”). While numerous large carp were also found at sites N34 and N47, most were young-of-the year fish (3-6” in length) indicating good reproduction in the lower reaches of the study area. The large carp were collected in the deep runs and holes (usually >5- 6’ depth) at these sites.
The introduced species (non-natives) were generally not as well represented at most sites compared to the native fish species. The exceptions were at site S84 where 5 of the 8 species collected were non-natives, and at site N34 half of the 16 species were non-natives. Most of the introduced fishes have likely washed into the river from ponds/lakes and reservoirs in the watershed, particularly the trout (various species) and walleye which are regularly stocked by CDOW in Chatfield and Cherry Creek Reservoirs, along with other species such as yellow perch, black crappie, bluegill, and largemouth bass that are also occasionally
Aquatics Associates, Inc. 24 May 2010 Aquatic Monitoring Program for SPCURE, 2008 stocked in these two reservoirs (CDOW 2008). The walleye found at the farthest downstream sites (N34 and N47) likely originated in Cherry Creek, whereas the trout found at the two upper sites (S84 and S76) are no doubt relicts from stocking in Chatfield Reservoir. Stream temperatures likely remain sufficiently cold for trout survival in the upper reaches of the SPR as well as sufficiently cool in the lower reaches of the study area for walleye which is a cool water fish.
IBI Scores
Fish IBI scores ranged between 25 and 45 for the SPR sites in 2008 (Table 3, Figure 4). The lowest IBI score was 25 at site S21/22 and the highest score was 45 at site N34. Two sites, S76 and S21/22 were rated as very poor with only site N34 rated as good. Otherwise, sites S84, S51, and S30 were rated as poor, while sites N18 and N45/46 were rated as fair. The comparatively lower scores at sites S76 and S21/22 (very poor category) were primarily due to the relatively high numbers of both suckers and omnivores and the low abundance of the specialized insectivore longnose dace. In fact, these three IBI metrics (i.e., % white suckers, % omnivores, and % specialized insectivore) were usually responsible for depressing most of the site scores, with those sites that had poor and fair ratings helped by the comparatively higher metric scores related to numbers of total species, total number of individuals, or numbers of minnow species. At site N34 where the population was rated as good, the maximum individual metric score of 5 was assigned to 6 of the 11 total metrics which included total number of species, number of sunfish species, % suckers (low), % specialized insectivores, numbers of individuals collected, and % disease (low). Furthermore, none of the individual metric scores were lower than 3 at this site. Sites N18 and N34 were the only two sites that had scores of 5 due to low numbers of suckers (% suckers metric), and site N34 was the only site that had a score of 5 for high numbers of longnose dace (% specialized insectivore metric).
As mentioned in the methods, the IBI scores for SPR study reach should be interpreted with caution as the IBI methodology was originally developed for mesic midwestern streams, which have comparatively greater species richness and numbers than the generally depauperate Great Plains streams (Bramblett and Fausch 1991). Sprague et al. (2006) in their exhaustive study of fish in the SPR basin found no strong associations between urban-related hydrology or urbanization impacts. The lack of good correlations between fish population responses to urbanization impact variables in Colorado transition-zone streams is largely because the populations are comprised of few dominant native species (usually <6) most of which are habitat generalists (Bramblett and Fausch 1991, Schrader 1989, Sprague et al. 2006, and Zuellig et al. 2007). The fish IBI values themselves, however should provide a suitable baseline against which future changes in fish populations in the SPR can be compared.
Aquatics Associates, Inc. 25 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Fish Disease
Fish disease in the form of “black spot disease” was found in some fish collected at the SPR sites, but the incidence was very low. Documenting the incidence of disease was performed since it is one of the fish IBI metrics (% disease). It was also a potential concern because of the heavy incidence of black spot disease observed by AAI in ongoing monitoring studies of Big Dry Creek, a tributary to the SPR which flows from Standley Lake to Fort Lupton. Black spot disease is expressed as subcutaneous black spots (<0.5 mm in diameter) on the body and fins of infected fish and are the metacercaria stage of a specific flatworm (digenetic trematodes) which are parasitic on certain fish-eating birds. An important intermediate host is aquatic snails (Hoffman 1999, Walker 2004). Snails were relatively scarce or absent at the SPR sites, which is likely the reason for the very low incidence of black spot disease in the study area. No other researchers have reported the occurrence of fish disease in SPR Segments 6 and 14.
Of the fish species that are known to be susceptible to black spot disease (Hoffman 1999), the susceptible fish species collected at the SPR sites so far include fathead minnows, longnose dace, creek chubs, white suckers, and longnose suckers. The incidence of black spot disease was <0.1% at three sites and was slightly higher at four sites (0.2 to 0.3%). The incidence of disease was more notable at site S21/22 where 10 of the 358 fish (2.9%) collected exhibited only slight levels of black spot disease. Of the 10 fish with the disease, 9 were white suckers. Overall, the incidence of fish disease observed in 2008 was very low to nonexistent at the SPR sites. Therefore, disease is likely a non-issue, but will continue to be monitored during subsequent fish sampling events.
3.2.2 Fish Mercury and Selenium Concentrations
Laboratory results of the mercury and selenium whole body fish analyses by sampling site are presented in Appendix C. Results of selenium analysis for selected fish species and the eight sites are presented in Table 4 including the mean value and range per species and the mean value for all fish at each site. Results of the two metals in fish tissue are discussed separately below. Comparisons of whole body selenium concentrations for fish from the SPR study to other SPR basin streams as well as other applicable studies are provided in Table 5.
Aquatics Associates, Inc. 26 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Mercury
Mercury was detected in only 2 of the 36 fish samples analyzed, which were the white sucker sample from site N18 (0.25 ug/g (ppm), dry weight) and carp sample from site N34 (0.20 ppm). These values are laboratory estimates as the results were between the MDL (Method Detection Limit; 0.03 ppm) and PQL (Practical Quantification Limit; 0.20 ppm). These concentrations are well below the EPA’s fish consumption limit of 0.3 ppm, wet weight (1.5 ppm, dry weight). Since the majority of mercury is stored in the fish’s fat and organ tissues (Belsile et al. 2006), it is highly unlikely that mercury would have been detected in the edible muscle tissue of these fish at such low concentrations.
Selenium
The site means (mean of all fish collected at each site) for the selenium analysis in fish tissue samples collected in 2008 at the SPR sites indicate an apparent steady increase in fish exposure to environmental selenium in a downstream direction as far as site S21/22 (2.7 to 6.7 ppm), while downstream from this site mean selenium concentrations level off at sites N18 through N47 with concentrations ranging between 6.4 and 7.1 ppm (Table 4). Overall, fish concentrations ranged from 1.8 ppm in white suckers (bottom omnivore) at site S84 immediately below Chatfield Reservoir to 14.5 ppm in longnose dace (bottom insectivore) at the farthest downstream site N47. For three of the individual species, specifically white suckers, longnose dace, and bass (smallmouth and/or largemouth, piscivores), selenium concentrations generally tended to increase at each succeeding downstream site. White suckers and bass had the highest concentrations (5.8 and 6.2 ppm, respectively) at site N34, while the highest concentration for longnose dace was at site N47 (14.5 ppm). In contrast, for common carp (bottom omnivore), the lowest selenium concentration was at site N47 (4.3 ppm) and was highest at site S21/22 (10.5 ppm) (Table 4). For fathead minnows (water column omnivore), selenium concentrations were rather uniform and varied only slightly from site to site with the highest concentration (6.3 ppm) recorded at site N47. Interestingly, except for carp, the highest selenium concentration for each species sampled was at either site N34 or N47.
Longnose dace (bottom insectivore) had the highest mean whole body selenium concentration of 8.1 ppm (range 1.9 to 14.5 ppm) and also contained the highest individual selenium concentration for all fish sampled at each site, except site S76 where fathead minnows had the highest concentration of 5.0 ppm (vs. 4.3 ppm for longnose dace). Longnose dace feed primarily on benthic invertebrates that have fed on periphytic algae and detritus, thereby bioaccumulating environmental selenium. Longnose dace also likely passively ingest contaminated sediments or algae while feeding on insects. The relative uniformity
Aquatics Associates, Inc. 27 May 2010 Aquatic Monitoring Program for SPCURE, 2008 of the selenium concentrations in the fathead minnow, a water column feeder, may be due to flow fluctuations in the SPR caused by periodic releases from Chatfield Reservoir of water with lower selenium concentrations and the fact that they don’t feed on the bottom where selenium concentrations are likely to be higher and less uniform. Interestingly, the mean concentration of selenium in the smallmouth and largemouth bass collected from the SPR study sites was the second lowest (4.6 ppm) next to white suckers at 3.6 ppm. Since these piscivores are at the top of the food chain, it would be expected that according the literature they would have higher or possibly the highest concentrations of selenium of all the fish sampled. A likely explanation for the lower concentrations in the bass is that all the specimens collected were relatively young (~age 1+; only young fish were available) and have had insufficient time to bioaccumulate selenium to higher concentrations.
In comparison to fish from other streams in the SPR drainage, selenium concentrations in fish at the SPR sites collected in 2008 were comparable to or well below those found in other studies (Table 5). For example, in a 2004 study of Big Dry Creek (north of Denver, from Standley Lake to Wattenberg), AAI (2005) found mean concentrations of selenium for the entire study area to be substantially higher in both longnose dace and fathead minnows than in the SPR study specimens (13.3 vs. 8.1 ppm and 11.7 vs. 5.2 ppm, respectively). For longnose dace, selenium concentrations ranged from 1.9 to 14.5 ppm in the SPR compared to 8.5 to 17.0 ppm in Big Dry Creek, while fathead minnow selenium concentrations ranged from 4.4 to 6.3 ppm in the SPR compared to 7.5 to 15.5 ppm in Big Dry Creek. Brown and Caldwell (2003) reported selenium concentrations in fathead minnows (whole body) ranging from 3.2 ppm in upper Sand Creek to 19.4 ppm in Toll Gate Creek (tributaries to the South Platte River) collected in 2002. No other fish species were analyzed in that study.
In studies conducted in high plains streams, May el al. (2001) reported selenium concentrations in fish from the Republican River in eastern Colorado that were also generally higher than those in the SPR study with mean concentrations of 9.56 ppm for white suckers (vs. 3.6 ppm, SPR), 7.88 ppm for fathead minnows (vs. 5.2 ppm, SPR), 6.86 ppm for carp (vs. 6.9 ppm, SPR), and 8.44 ppm for largemouth bass (vs. 4.6 ppm, SPR) (Table 5). In another selenium study conducted by May et al. (2008) on fish from the Solomon River in north-central Kansas, selenium concentrations in carp from three sites in a downstream direction were 7.8, 9.3, and 10.4 ppm, while for the red shiner (Cyprinus lutrensis) selenium concentrations were 7.0, 5.8, and 10.0 ppm. Only carp appeared to have similar selenium concentrations in all three studies including the 2008 SPR study and studies by May et al. (2001, 2008). Lastly, selenium concentrations in muscle tissue from forage fish in the Colorado River had mean annual concentrations of 8.6, 20.2, and 27.2 ppm (Simmons and Wallschlager 2005).
Aquatics Associates, Inc. 28 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Fish tissue selenium concentrations for the 2008 SPR collections were generally near or above the Lemly (1998) suggested whole body fish criterion of 4.0 ppm dry wt. (78% of values were above), but were mostly below the EPA (2004) suggested criterion of 7.9 ppm (only 16.7% were above) and the criterion suggested by DeForest (1999) of 9.0 ppm (only 13.8% were above). None of the fish collected from the SPR sites nor those in Big Dry Creek showed any signs of selenium toxicity (e.g., deformities, lowered reproduction and recruitment, mortality, etc.). This does not appear to be an unusual phenomenon in stream environments as reported in the literature discussed below.
Fish populations in the La Plata River where instream concentrations were as high as 12 ppm showed no obvious signs of impairment, and according to the EIS, these fish may have adapted to the elevated selenium concentrations (WWE 2007). In addition, tissue analyses of fish from the La Plata and Animas Rivers did not indicate biomagnification to levels of selenium that could reproductively impair fish. Of the tissue concentrations in fish collected from the Republican River and Solomon River, May et al. (2001, 2008) reported that 75% and 55% of the fish concentrations, respectively, exceeded the 4.0 ppm biological effects threshold (compared to 78% for the 2008 SPR study), and no impairment to the overall fisheries for both studies was also noted. As reported for the La Plata River study, May et al. (2001) also postulated that because the selenium source was from naturally occurring shales in the watershed, that over a large span of time, the fish likely have adapted to the elevated selenium concentrations.
Several recent studies have compared the ecotoxicity of selenium in lentic (standing) vs. lotic (flowing) water environments and found selenium to be less toxic in lotic systems than in lentic systems (Hillwalker et al. 2006, Orr et al. 2006, Simmons and Wallschlager 2005). Reasons for this difference relate mainly to the ecological and biogeochemical differences between lotic and lentic systems and how these differences affect the chemical forms of selenium present in each system. Because the sediments in most lotic systems are largely oxic (oxygenated), the predominant form of selenium in streams is inorganic selenate compared to lentic systems where the sediments are more anoxic and form a reducing environment resulting in greater amounts of inorganic selenite, organic selenium, and elemental selenium. Selenite is the most biologically available form of selenium, especially to algae and cyanobacteria where in it is converted to the more toxic and bioaccumulative organic seleno-amino forms (Simmons and Wallschlager 2005). Selenate on the other hand is less toxic than other forms, as well as being less readily bioaccumulated, especially in the presence of sulfate which inhibits its uptake in algae, macroinvertebrates, and fish (Simmons and Wallschlager 2005). As reported by WWE (2007), selenate is the predominant form of selenium in Big Dry Creek; therefore, selenate is likely the most prevalent form of selenium in the South Platte River as well.
Aquatics Associates, Inc. 29 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Despite the apparently “elevated” tissue concentrations (i.e., concentrations above several suggested criteria), the lack of any obvious toxic effects in the fish populations found in the SPR, as well as Big Dry Creek and the other streams discussed, indicates the likelihood that some form of adaptation to naturally occurring selenium can and does occur in fish populations. Additionally, the predominant chemical form of selenium in fish tissues collected from SPR is the relatively non-toxic selenate form. Toxic effects were noted by Lemly (1993) in fathead minnows and largemouth bass in the form of deformities at tissue concentrations of ~19.6 ppm, which is higher than any of the 2008 concentrations found in SPR fish. Lemly’s fish however, were from a lentic environment where the more toxic organic seleno-amino form of selenium was much more prevalent than the other inorganic forms and more readily bioaccumulated within the food chain (Simmons and Wallschlager 2005).
It appears therefore safe to assume, that based on the limited amount of 2008 data, selenium concentrations in SPR fish, though mostly higher than Lemly’s tissue limit of 4.0 ppm (most were less than the EPA and DeForest limits of 7.9 and 9.0 ppm, respectively), are not a threat to the overall health of these fish populations.
3.2.3 Fish Summary
In summary, the fish community in the urban reach of the South Platte River appears most influenced by the widely fluctuating stream flows as well as channelization. Ten of the 22 total species collected were native to the SPR drainage. Suckers were predominant at sites upstream from site S21/22, while fathead minnows, longnose dace (though common at most all sites), and common carp generally became more abundant at sites N18 through N47. Creek chubs were also well represented and were evenly distributed from site S51 downstream. Interestingly, both the Iowa darter (State species of special concern) and johnny darter were found in good numbers in the SPR study area. The Iowa darter was limited to one site S76, while the johnny darter was collected at six of the eight sites. The incidence of disease (black spot) was very low to nonexistent with the highest incidence occurring at site S21/22. Nonetheless, all individuals collected appeared healthy and in good condition. The IBI analysis showed spatial differences with the lowest IBI scores noted at sites S76 and S21/22 suggesting that these sites may be more impacted than the other sites. The discriminatory effectiveness of the IBI will likely be more reliable in subsequent years as more data become available. Furthermore, the fish population showed no apparent effects due to slightly elevated selenium concentrations and nearly all mercury concentrations were less than the method detection limit. None of the fish population results for 2008 suggest any stress from temperature modifications due to municipal/industrial effluent discharges in the SPR study area.
Aquatics Associates, Inc. 30 May 2010 Aquatic Monitoring Program for SPCURE, 2008
3.3 MACROINVERTEBRATES
Macroinvertebrates were collected at all 13 sites on the SPR in the fall of 2007 and 2008. Macroinvertebrate sampling was performed at six of the sites in the spring of 2008 and the artificial substrate sampling using rock baskets was conducted at the same six sites in the fall 2008 (Table 2). The predominant and important species found in fall 2007 and 2008, spring 2008, and the rock basket 2008 samples are presented in Table 6. Key macroinvertebrate community metrics for the fall of 2007 and 2008 are summarized in Table 7, and community metrics for spring 2008 and the 2008 rock basket samples are provided in Tables 8 and 9, respectively. A complete list of macroinvertebrate species and their occurrence on each of the four sampling events is presented in Appendix D. A list of the predominant and important species collected and their respective densities and percent abundances is also provided in Appendix D. Summaries of community parameters, relative abundance, and density for the major groups (Orders) collected, as well as summaries of selected community metrics such as species diversity, HBI, ICI, EPT taxa, total taxa, density, and the ICI/HBI ratio are provided in Appendix D. The percent abundance of the major macroinvertebrate taxonomic groups collected in the kick samples is presented graphically in Figure 5 for the spring 2008 and the fall 2007 and 2008. A comparison of total taxa and density data for kick samples is presented in Figure 6 for the spring and fall seasons. Selected community metrics for EPT taxa vs. total taxa, HBI values vs. % Oligochaeta, and HBI values vs. ICI scores for fall 2007 and 2008 are compared and graphically presented in Figure 7, while these comparisons for spring 2008 are presented in Figure 8. Similar graphs for the rock baskets are provided in Figure 9 (% relative abundance by order), Figure 10 (density vs. number of taxa), and Figure 11 (metrics comparisons).
3.3.1 Kick Samples
Community Characteristics
Macroinvertebrate study results for the 2007 and 2008 spring and fall sampling events in the SPR are discussed below. The results indicate that the macroinvertebrate community was dominated by aquatic insects, oligochaetes (aquatic worms), and turbellarians (flatworms). A total of 17 macroinvertebrate orders were represented in the fall collections (15 in 2007, 17 in 2008), while 12 orders were collected in the spring 2008. The most taxa were collected in the fall 2008 with a total of 66 taxa compared to 63 taxa in the fall of 2007 and 60 taxa in the spring 2008 (Appendix D). In the fall, the macroinvertebrate community in the study reach was generally dominated by caddisflies (Trichoptera) in 2007 and by mayflies (Ephemeroptera) in 2008. Interestingly, in both years oligochaetes (mainly tubificids) were
Aquatics Associates, Inc. 31 May 2010 Aquatic Monitoring Program for SPCURE, 2008
TABLE 6
OCCURRENCE OF PREDOMINANT AND IMPORTANT MACROINVERTEBRATE SPECIES COLLECTED FROM SOUTH PLATTE RIVER SITES, SPRING 2008 AND FALL 2007 AND 2008
Kick Samples Rock Baskets Taxa Fall 2007 Fall 2008 Spring 2008 Fall 2008 TURBELLARIA (flatworms) Dugesia sp. X X X
OLIGOCHAETA (aquatic worms) Enchytraeidae X X X Nais sp. X X Tubificidae X X X
AMPHIPODS (scuds) Crangonyx sp. X X X X Hyalella azteca X
EPHEMEROPTERA (mayflies) Acentrella insignificans XX Baetis tricaudatus XX X Tricorythodes explicatus XX X X
TRICHOPTERA (caddisflies) Cheumatopsyche sp. X X X Hydropsyche sp. X X X X
DIPTERA Chironomidae (midges) Chironomus sp. X Cricotopus sp. X X X X Microtendipes sp. X X X Orthocladius sp. X X Phaenopsectra sp. X Rheocricotopus sp. X Saetheria tylus X Empididae (dance flies) Hemerodromia sp. X Simuliidae (black flies) Simulium sp. X Total Taxa by Event 63 66 60 71
Aquatics Associates, Inc. 32 May 2010 Aquatic Monitoring Program for SPCURE, 2008
TABLE 7
SUMMARY OF KEY COMMUNITY PARAMETERS AND INDICES FOR MACROINVERTEBRATE SAMPLES COLLECTED FROM SOUTH PLATTE RIVER SITES, FALL 2007 AND 2008
Fall 2007 - Kicks Metric
Site EPT Taxa Total Taxa ICI HBI % Oligochaetes ICI/HBI ratio % Sprawlers S84 8 31 32 4.79 1.2 6.68 46.6 S76 9 30 36 4.61 3.1 7.81 25.5 S62 9 25 30 4.70 1.9 6.38 12.8 S51 8 22 26 4.63 1.2 5.62 27.8 S34 8 24 30 4.66 6.6 6.44 7.8 S30 8 37 32 5.82 18.4 5.50 12.2 S21/22 6 30 26 6.22 31.8 4.18 3.2 S7 6 25 24 6.82 40.0 3.52 2.1 N4 6 29 26 4.75 5.8 5.47 2.0 N18 7 31 28 5.58 13.6 5.02 1.9 N28 8 36 32 5.25 11.7 6.10 3.2 N34 7 30 30 5.22 11.6 5.75 1.5 N45/46 7 27 24 5.69 17.5 4.22 3.7
Fall 2008 - Kicks Metric
Site EPT Taxa Total Taxa ICI HBI % Oligochaetes ICI/HBI ratio % Sprawlers S84 6 35 26 5.45 1.3 4.77 10.0 S76 6 28 26 4.61 0.5 5.64 53.0 S62 6 25 30 4.49 0.1 6.68 56.8 S51 7 27 24 4.58 0.8 5.24 55.8 S34 7 31 30 4.75 0.9 6.32 19.9 S30 8 35 28 5.12 1.1 5.47 11.1 S21/22 6 26 24 5.74 13.6 4.18 5.2 S7 8 31 22 6.63 33.9 3.32 11.6 N4 6 25 24 5.93 16.1 4.05 22.1 N18 6 35 30 5.42 1.4 5.54 7.5 N28 7 33 26 5.89 13.8 4.41 8.6 N34 7 30 24 5.97 9.2 4.02 8.2 N45/46 7 30 24 5.96 25.6 4.03 4.8
Bold indicates notable upstream/downstream changes.
Aquatics Associates, Inc. 33 May 2010 Aquatic Monitoring Program for SPCURE, 2008
TABLE 8
SUMMARY OF KEY COMMUNITY PARAMETERS AND INDICES FOR MACROINVERTEBRATE SAMPLES COLLECTED FROM SOUTH PLATTE RIVER SITES, SPRING 2008
Spring 2008 - Kicks Metric
Site EPT Taxa Total Taxa ICI HBI % Oligochaetes ICI/HBI ratio % Sprawlers S84 4 31 18 7.54 41.5 2.39 24.7 S76 6 33 24 7.43 59.1 3.23 21.7 S30 4 25 18 7.24 50.2 2.49 3.5 S21/22 4 24 14 8.33 75.4 1.68 2.6 N18 5 29 18 7.33 36.2 2.46 2.1 N45/46 4 25 14 7.93 51.4 1.77 2.4
Bold indicates notable upstream/downstream changes.
TABLE 9
SUMMARY OF KEY COMMUNITY PARAMETERS AND INDICES FOR MACROINVERTEBRATE SAMPLES COLLECTED IN ROCK BASKET SAMPLES FROM SOUTH PLATTE RIVER SITES, FALL 2008
Fall 2008 - Rock Baskets Metric
Site EPT Taxa Total Taxa ICI HBI % Oligochaetes ICI/HBI ratio % Sprawlers S84 2 20 10 6.44 0.1 1.55 7.7 S76 3 29 22 5.42 0.8 4.06 32.0 S30 7 38 24 5.05 1.9 4.75 7.0 S21/22 8 38 28 4.91 3.1 5.70 8.7 N18 9 38 26 5.87 0.2 4.43 9.9 N45/46 6 38 28 5.56 13.7 5.04 6.4
Bold indicates notable upstream/downstream changes.
Aquatics Associates, Inc. 34 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 5 PERCENT RELATIVE ABUNDANCE OF MACROINVERTEBRATE TAXONOMIC GROUPS FOR KICK SAMPLES FROM SOUTH PLATTE RIVER SITES, SPRING AND FALL 2007 AND 2008
EPHEMEROPTERA TRICHOPTERA DIPTERA OLIGOCHAETA TURBELLARIA OTHER GROUPS
SPRING 2008 100%
80%
60%
40%
20%
0%
4 6 2 1 4 0 2 4 8 8 4 /2 S7 N 1 2 3 S8 S7 S6 S5 S3 S3 1 N N N 5/46 4 S2 N
FALL 2007 100%
80%
60%
40%
20%
0%
PERCENT RELATIVE ABUNDANCE 2008 100%
80%
60%
40%
20%
0%
4 6 2 1 4 0 4 S7 N 18 28 34 S8 S7 S6 S5 S3 S3 1/22 N N N 45/46 S2 N
STUDY SITE
Upstream Downstream
Aquatics Associates, Inc. 35 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 6 MACROINVERTEBRATE DENSITY AND TOTAL NUMBER OF TAXA FOR KICK SAMPLES FROM SOUTH PLATTE RIVER SITES, SRING AND FALL 2007 AND 2008
DENSITY - 2008 DENSITY - 2007 TAXA - 2008 TAXA - 2007
SPRING 2008 14000 40 12000 30 10000 ) 2 8000 20 6000
4000 10 2000
0 0 TAXA OF NUMBER
7 4 6 84 76 62 51 34 30 S N 18 28 34 4 S S S S S S N N N 21/22 45/ S N
FALL 2007 & 2008 14000 40 12000 30 10000 MACROINVERTEBRATE DENSITY (N/m 8000 20 6000
4000 10 2000 0 0
7 4 6 84 76 62 51 34 30 S N 18 28 34 4 S S S S S S N N N 21/22 45/ S N
STUDY SITE
Upstream Downstream
Aquatics Associates, Inc. 36 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 7 COMPARSION OF SELECT MACROINVERTEBRATE COMMUNITY PARAMETERS FOR KICK SAMPLES AT SOUTH PLATTE RIVER SITES, FALL 2007 AND 2008
EPT Taxa - 2007 EPT Taxa - 2008 Total Taxa - 2007 Total Taxa - 2008 40 40 35 35 TOTAL TAXA
A 30 30 25 25 20 20 15 15 EPT TAX 10 10 5 5 0 0
7 84 76 62 51 34 30 22 S N4 S S S S S S N18 N28 N34 21/ S N45/46
HBI - 2007 HBI - 2008 % Oligochates - 2007 % Oligochates - 2008 10 40.0 % OLIGOCHAETES 9 8 30.0 7 6 5 20.0 4 3 10.0 2 HBI VALUES 1 0 0.0
7 84 76 62 51 34 30 22 S N4 S S S S S S N18 N28 N34 21/ S N45/46
HBI - 2007 HBI - 2008 ICI - 2007 ICI - 2008 10 40
9 35 ICI SCORES 8 30 7 6 25 5 20 4 15 3 10 2
HBI VALUES 1 5 0 0
7 84 76 62 51 34 30 22 S N4 S S S S S S N18 N28 N34 21/ S N45/46
STUDY SITES
Upstream Downstream
Aquatics Associates, Inc. 37 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 8 COMPARSION OF SELECT MACROINVERTEBRATE COMMUNITY PARAMETERS FOR KICK SAMPLES AT SOUTH PLATTE RIVER SITES, SPRING 2008
EPT Taxa - 2008 Total Taxa - 2008
40 35
35 30 TOTAL TAXA
A 30 25 25 20 20
EPT TAX 15 15 10 10 5 5 0 0 S84 S76 S30 S21/22 N18 N45/46
HBI - 2008 % Oligochates - 2008
10 80.0 % OLIGOCHAETES 9 8 60.0 7 6 5 40.0 4 3
HBI VALUES 20.0 2 1 0 0.0 S84 S76 S30 S21/22 N18 N45/46
HBI - 2008 ICI - 2008
10 40
9 35 ICI SCORES 8 30 7 6 25 5 20 4 15 3
HBI VALUES 10 2 1 5 0 0 S84 S76 S30 S21/22 N18 N45/46
STUDY SITES
Upstream Downstream
Aquatics Associates, Inc. 38 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 9 PERCENT RELATIVE ABUNDANCE OF MACROINVERTEBRATE TAXONOMIC GROUPS FOR ROCK BASKET SAMPLES FROM SOUTH PLATTE RIVER SITES, FALL 2008
EPHEMEROPTERA TRICHOPTERA DIPTERA OLIGOCHAETA TURBELLARIA OTHER GROUPS
2008 100%
80%
60%
40%
20%
0% S84 S76 S30 S21/22 N18 N45/46 PERCENT RELATIVE ABUNDANCE STUDY SITE
Upstream Downstream
Aquatics Associates, Inc. 39 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 10 MACROINVERTEBRATE DENSITY AND TOTAL NUMBER OF TAXA FOR ROCK BASKET SAMPLES FROM SOUTH PLATTE RIVER SITES, FALL 2008 ) 2 DENSITY TAXA
12,804 FALL 2008 3000 40 2500 NUMBER OF TAXA OF NUMBER 30 2000
1500 20
1000 10 500
0 0
MACROINVERTEBRATE DENSITY (N/m S84 S76 S30 S21/22 N18 N45/46
STUDY SITE Upstream Downstream
Aquatics Associates, Inc. 40 May 2010 Aquatic Monitoring Program for SPCURE, 2008
FIGURE 11 COMPARSION OF SELECT MACROINVERTEBRATE COMMUNITY PARAMETERS FOR ROCK BASKET SAMPLES AT SOUTH PLATTE RIVER SITES, FALL 2008
EPT Taxa - 2008 Total Taxa - 2008
40 40
35 35 TOTAL TAXA
A 30 30 25 25 20 20
EPT TAX 15 15 10 10 5 5 0 0 S84 S76 S30 S21/22 N18 N45/46
HBI - 2008 % Oligochates - 2008
10 15.0 % OLIGOCHAETES 9 8 7 10.0 6 5 4 5.0 3 HBI VALUES 2 1 0 0.0 S84 S76 S30 S21/22 N18 N45/46
HBI - 2008 ICI - 2008
10 40
9 35 ICI SCORES 8 30 7 6 25 5 20 4 15 3
HBI VALUES 10 2 1 5 0 0 S84 S76 S30 S21/22 N18 N45/46
STUDY SITES
Upstream Downstream
Aquatics Associates, Inc. 41 May 2010 Aquatic Monitoring Program for SPCURE, 2008 either nearly dominant or dominant at sites S21/22 and S7, which are downstream from the effluent discharges from L/E WWTP and Xcel’s Arapahoe Plant (Figure 5). In the spring on the other hand, all six sites were dominated by oligochaetes, mainly the species Nais sp. In general, the initial 2007 and 2008 data show as noted in other studies (GEI 2009, Zuellig et al. 2007) that the benthic macroinvertebrate community of SPR Segments 6 and 14 reflects the effects of meta stressors such as stream channelization, effluent dominance, and extremes in stream flows (i.e., storm runoff, releases from Chatfield Reservoir). The community is further affected by the predominance of sand and gravel substrates present in the glide habitats of the river and the paucity of stable riffles.
Fall 2007 and 2008. Number of taxa collected in fall 2007 ranged from 22 to 37 taxa and in 2008 from 25 to 35 taxa, with no notable upstream to downstream trends (Figure 6, Appendix D). Higher numbers of taxa tended to be collected at sites S84, S30, N18, and N28, whereas the lower numbers of taxa were collected at sites S62 and S51. Macroinvertebrate densities in 2007 generally decreased in a downstream direction from a maximum of 14,985 organisms/m2 at site S76 to a low of 1,476 organisms/m2 at site N45/46. This trend however was not observed in fall 2008 as total densities fluctuated from site to site ranging from 1,451 (site N4) to 9,917 organisms/m2 (site S62) (Figure 6). Such year-to-year fluctuations are common in plains streams (Voelz et al. 2005). As mentioned above, caddisflies were the dominant aquatic insect group in 2007 followed by mayflies, dipterans, and oligochaetes. In 2008, mayflies were the dominant group followed by dipterans, caddisflies, turbellarians, and lastly oligochaetes (Figure 5, Appendix D).
Caddisflies in both 2007 and 2008 were dominated by the net-spinning family Hydropsychidae with the moderately sensitive species Hydropsyche sp. the dominant caddisfly taxa at all sites except at site S84 just below Chatfield Reservoir, where Cheumatopsyche sp. was dominant in both years (Table 6, Appendix D). In 2007, Hydropsyche sp. abundance ranged from <1 to 47.1% (highest at site S34) with this species the dominant taxon overall at 9 of the 13 sites sampled in fall 2007. In 2008, however Hydropsyche sp. abundance ranged from <1 to only 15.9% (highest at site S21/22) and it was not the dominant taxon at any of the 13 sampling sites (Appendix D). These net-spinning hydropsychids construct silken nets and are basically filter feeders as they consume particles of detritus, bacteria, and algae that become trapped on the nets. Reasons for this somewhat dramatic change in dominance between these two years, other than the natural variability of aquatic macroinvertebrate, are not readily apparent.
Mayflies were second in abundance in 2007 and first in 2008 (Figure 5), and were represented by three predominant species including Acentrella insignificans, Baetis tricaudatus, and Tricorythodes explicatus.
Aquatics Associates, Inc. 42 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Tricorythodes expilcatus was the dominant taxon at sites S84 and S51 in 2007, while in 2008 it was dominant at 4 of the 13 sites with three of the sites in consecutive order (sites S76, S62, and S51) and the fourth at site N4 farther downstream (Appendix D). Tricorythodes explicatus tended to be the most abundant mayfly in the upper sections of the study area (sites S84 through S34). In both years, mayflies were the least abundant at sites S21/22 and S7, whereas their abundance increased noticeably at sites N4 through N45/46. In 2007, the moderately sensitive A. insignificans replaced T. explicatus at the sites downstream from S7 as the most abundant mayfly; however this was not the case in 2008 as all three of these predominant species were dominant at sites downstream from S7. For instance, A. insignificans was dominant (34.4%) at site N28, B. tricaudatus was dominant at site N18 (26.4%), and T. explicatus was dominant at site N4 (16.3%). The ubiquitous B. tricaudatus was consistently represented throughout the sampling reach in both years with their relative abundances generally ranging between 1% and 7.1% in 2007, but from <1 to 29.5% in 2008. While mayflies are generally sensitive to poor water quality conditions, the three predominant species discussed above are commonly found in high plains streams and can apparently tolerate a wide range of environmental stressors. Tricorythodes explicatus is a sprawler/collector-gatherer, while A. insignificans and B. tricaudatus are clinger/collector-gatherers (Merritt et al. 2008). The shift in overall dominance in 2008 from caddisflies to mayflies is likely due to the inherent natural variability of aquatic insect populations.
Dipterans were generally common throughout the study reach and were third most abundant group in 2007 and second in 2008. The moderately tolerant midge Cricotopus sp. (family: Chironomidae) was usually most abundant in both years, while the midge Microtendipes sp. (moderately tolerant) was occasionally present as well. In 2007, the abundance of Cricotopus sp. ranged from 1.6 to 20.9%, while in 2008 when dipterans were slightly more numerous, its abundance ranged from 2.7% to a high of 22.1% at site N34 where it was also the dominant taxon for that site.
Of the non-insect groups, oligochaetes and the flatworm Dugesia sp. predominated. Oligochaete worms were the fourth most abundant group in 2007 and fifth in 2008, and were comprised mainly of Nais sp. and members of the family Tubificidae (tubificids), with both organisms highly tolerant of organic enrichment (Figure 5). Nais sp. was present in generally low numbers at all sites ranging from <1 to 12.6% in 2007, while in 2008 very few were collected with none being collected at two sites, <1% at 10 sites, and 1.2% at one site (Appendix D). As mentioned previously, tubificids were the dominant oligochaetes in both years at sites S21/22 and S7 with percent abundances in 2007 of 28.4 % and 30.7 %, respectively, and 13.4 % and 33.7 % in 2008, respectively. In both years, tubificids were the dominant taxon at site S7 in the fall. Oligochaete abundance was also relatively high (25.6%) at site N45/46 in 2008. A predominance of tubificid worms has been shown by numerous researchers to be a common
Aquatics Associates, Inc. 43 May 2010 Aquatic Monitoring Program for SPCURE, 2008 occurrence within relatively short distances downstream from WWTP outfalls (Hynes 1971, 1972, Kondratieff et al. 1984).
Turbellarians (flatworms) were the fifth most abundant group collected in 2007 and fourth most abundant in 2008 (Figure 5). Dugesia sp. was collected at all sites with their abundance in 2007 ranging from <1% to 24.8% (sites S76 and N4, respectively), and from 1.1 to 29.1 % (sites S84 and S34) in 2008. Dugesia sp., like the predominant mayfly and caddisfly species found in the study reach, is moderately tolerant of organic pollution. Interestingly, Dugesia sp. was the dominant taxon at 3 of the 13 sampling sites in 2008 (23.0 to 29.1% at sites S34, S21/22, and N45/46), but at none of the sites in 2007. These flatworms are quite ubiquitous being found in most freshwater environments (Pennak 1978).
Spring 2008. The macroinvertebrate community collected in spring 2008 was notably different than that collected in either fall sampling period as expected. Instead of being dominated by either mayflies or caddisflies, the community was comprised mainly of oligochaetes and dipterans (Figure 5). Oligochaetes were dominant throughout the study reach with abundances ranging from 36.2 to 75.4%, while dipteran abundance ranged from 17.5 to 49.9% (Appendix D). The oligochaete Nais sp. was by far the most abundant species and was the dominant taxon at four of the six sites (S84 through S21/22), while the midge Cricotopus sp. was dominant at sites N18 and N45/46 at 42.3% and 34.5%, respectively. The highest abundance of Nais sp. was at site S21/22 (68.0%), immediately downstream from the L/E WWTP and Xcel outfalls. By comparison, AAI found this same occurrence (dominance of Nais sp.) downstream from municipal WWTP outfalls in Big Dry Creek in spring samples collected for biomonitoring studies for the Big Dry Creek Watershed Association (AAI 2002, 2005, 2007). According to Pennak (1978), naidid worms can produce new individuals asexually by budding every two or three days under the right conditions. This is likely the case especially in the spring downstream from the outfalls of WWTPs that can discharge relatively large amounts of organic matter which provides excellent feeding and reproductive conditions for these worms. Additionally, organic matter throughout the SPR study area tends to accumulate on the substrates during the winter low flow period until the higher spring flows scour the substrates of accumulated organic matter.
Taxa richness in spring 2008 ranged from 24 taxa at site S21/22 to 33 taxa at site S76. Densities were highest at site S30 (6,180 organisms/m2) and lowest site S84 (1,791 organisms/m2) (Figure 6). Notably, amphipods (scuds) were more abundant at site S84 (5.9%) than either mayflies or caddisflies, but were not collected at four of the other spring sites (Appendix D). Mayflies and caddisflies in the spring 2008 were overall third and fourth in abundance, respectively. For both groups, the same abundant taxa found in the fall were present in the spring. Baetis tricaudatus was the most abundant mayfly ranging from <1
Aquatics Associates, Inc. 44 May 2010 Aquatic Monitoring Program for SPCURE, 2008 to 23.4% (sites S76 and S30, respectively) with none collected at site S84, whereas A. insignificans were absent at two sites and their highest abundance was only 1.4%. Tricorythodes explicatus likewise was absent at two sites and its highest abundance was 18.1% at site S76. Although predominant in the fall, abundance of the caddisfly Hydropsyche sp. ranged from <1% to only 4.8% in spring. Turbellarians, while present at each site never represented more than 1.1% of the community. The low numbers of mayflies and caddisflies are likely most related to their respective life histories (rather than some anthropogenic perturbation) with these taxa still in either the egg or the very early instar stages and therefore not readily collected during the spring event.
Community Metrics
Fall 2007 and 2008. Metrics calculated for the fall macroinvertebrate data that indicated trends or appeared to best reflect the response of the macroinvertebrate community to various meta stressors and overall environmental stressors were the HBI, ICI, ICI/HBI ratio, % Oligochaeta, and % sprawlers. EPT taxa, though often found to be sensitive to stressful environmental conditions, were too few in number with site to site variability (between 6 and 9 taxa) insufficient to detect impairment differences with this metric (Table 7, Figure 7). Both the HBI and ICI scores reflect the number of tolerant organisms in the community and these two indices are most responsive to degraded water quality conditions. The % sprawlers on the other hand are more responsive to physical conditions such as substrate composition and flow fluctuations, while % Oligochaeta are somewhat responsive to both water quality and substrate conditions (i.e., favor soft sediments and organic matter). Although none of the calculated metrics showed marked responses to the main environmental stressors, both the HBI values and % Oligochaeta responded similarly (both increased) at sites S21/22 and S7 in the fall of both sampling years (Table 7, Figure 7). The abrupt increases in both years of % Oligochaeta at sites S21/22 and S7 coincided with increases in HBI values (scale 0-10), which were highest (worse) at these sites with HBIs of 6.22 and 6.82 at sites S21/22 and S7 in 2007, respectively, and HBIs of 5.74 and 6.63 at sites S21/22 and S7 in 2008. HBIs were comparatively lower (better) at sites upstream and downstream from sites S21/22 and S7 ranging from 4.49 to 5.82 upstream and from 4.75 to 5.97 downstream from these two sites. The relationship between HBI and % Oligochaeta metrics was particularly evident at those sites downstream from WWTPs. Most oligochaetes are highly tolerant aquatic organisms and respond to high nutrient levels by often becoming overwhelmingly abundant. The HBI was designed to measure nutrient/organic impacts on macroinvertebrate communities, so a direct correlation between the two metrics would be expected as was the case at these two sites (sites S21/22 and S7).
Aquatics Associates, Inc. 45 May 2010 Aquatic Monitoring Program for SPCURE, 2008
The ICI scores were either at or near their lowest (worse) also at sites S21/22 and S7 compared to the other upstream and downstream sites with ICIs of 26 and 24 in 2007, and 24 and 22 in 2008, respectively. Compared to the other sites, ICI scores in 2007 ranged from 24 to 36 at sites N45/46 and S76, respectively, and low ICI scores were also recorded at sites S51 and N4 (both ICIs 26) and at site N45/46 (ICI 24). In 2008, the lower ICI scores of 24 were also recorded for four sites (S51, N4, N34, and N45/46) and ICIs of 26 were recorded for three sites (S84, S76, and N28), whereas the highest ICI score of 30 was recorded at sites S62, S34, and N18. Overall, ICI scores in 2008 were slightly more depressed at most sites than in 2007. The greatest decrease was at site S76 where the ICI was 36 in 2007 vs. only 26 in 2008. This decrease was mostly attributable to the large increases in percent abundance of dipterans and non-insects (oligochaetes and turbellarians), with decreases in the number caddisfly taxa and their overall abundance. The overall lower ICI scores in 2008 were also largely related to changes in these same community characteristics. Regardless of the lower ICIs that were often observed in the fall, macroinvertebrate community condition was rated as fair at all sites in both 2007 and 2008, except at site S76 which was rated as good in 2007.
The ICI/HBI ratio appears to indicate impairment more clearly than either the ICI or HBI metric alone (Table 7). ICI/HBI ratios between ~3.3 and 4.3 (low, indicating possible impacts) were recorded at sites S21/22, S7, and N45/46 in both years and at sites N4 and N34 in 2008 only. Site S7 had the lowest ratios of 3.52 and 3.32, while site S21/22 had ratios of 4.18 in both years. Site N45/46 had low ratios (4.22 and 4.03) indicating the macroinvertebrate community at this site was more stressed than most of the remaining sites even though this site is not situated immediately downstream from effluent discharge points. This site however receives rather large and sudden inputs of often degraded water from the largest storm drain in Denver (9.4 mi2) which drains both a highly industrialized area and a large residential area in northeast Denver. Additionally, the predominant shifting sand substrates typical of this reach are overall less productive of macroinvertebrates. Comparatively higher ICI/HBI ratios (>6.0, less impacted) were noted at five sites in 2007 (S84, S76, S62, S34, and N28), four of which are upstream from the L/E WWTP and Xcel outfalls, but at only two upstream sites (S62 and S34) in 2008.
Percent sprawlers in both years tended to decease with distance downstream from Chatfield Reservoir with this occurring more dramatically in 2007 than in 2008 when the most abundant sprawler, T. explicatus (mayfly) continued to be more abundant downstream from site S21/22 in 2008 than in 2007 (Table 7). Many of the sprawlers are also midges, but not Cricotopus sp. the most abundant midge; therefore contributions of the other less abundant midges likely did not significantly affect this metric in the fall. Sprawlers were especially abundant at sites S76, S62, and S51 in 2008 where 53.0 to 56.8%
Aquatics Associates, Inc. 46 May 2010 Aquatic Monitoring Program for SPCURE, 2008 sprawlers were collected. Apparently habitat and/or water quality suitable for sprawlers diminishes in reaches downstream from site S30 or S34 as indicated by the fall 2007 and 2008 data.
Because of the natural variations in macroinvertebrate populations, as more data become available these key metrics should more readily determine if community changes are due to meta stressors, habitat, or normal population fluctuations.
Spring 2008. Because of the high abundances of the tolerant oligochaete Nais sp. at all sites sampled in spring, HBI values were notably higher and ICIs were lower than those recorded for either of the fall collections (Table 8, Figure 8). HBIs ranged from 7.24 to 8.33 indicating that all sites were stressed by organic enrichment in the spring. The highest HBI was at site S21/22, and the second highest value was at site N45/46 further indicating that these two sites are more stressed than most of the other SPR sites. ICI scores were also lowest (worse) at sites S21/22 and N45/46 (both ICIs 14). The ICI score was highest at S76 (ICI 24) as noted at this site in the fall 2007. Nonetheless, all ICI scores were in the fair category for the spring event. The ICI/HBI ratios for all sites were <3.5 (low, indicating possible impacts) with ratios at sites S21/22 and N45/46 the lowest at 1.68 and 1.77, respectively, compared to values >4.00 at these sites for both fall collections. EPT taxa were low with only 4 to 6 taxa collected, and showed no discernable trends among the spring sampling sites.
The % Oligochaetes was elevated at all sites ranging from 36.2% (site N18) to 75.4% (site S21/22). Oligochaete abundance was high at all sites in the spring, and the dramatic increases in % Oligochaetes noted in fall at sites S21/22 and N45/46 were not as pronounced in the spring. The % sprawlers was somewhat comparable to the fall with the highest abundance at sites S84 and S76, and fewer sprawlers were collected at site S30 and the remaining downstream sites.
Recent Studies. GEI (2008) collected macroinvertebrate samples in the fall 2005 at locations in SPR Segments 6 and 14 similar to those in this bioassessment study. As found by AAI in 2007 and 2008, the macroinvertebrate community was comprised mainly of mayflies, caddisflies, dipterans, and oligochaetes. Both mayflies and caddisflies were nearly equally abundant throughout the sampling reach in 2005 with caddisflies, mayflies, and dipterans each most abundant downstream from Belleview Ave. (AAI site S51). Densities in the GEI study ranged from 1,652 to 21,706 organisms/m2 at sites near 38th Ave. and downstream from Belleview, respectively (AAI sites N34 and S51). Except for the high density of 21,706 organisms/m2, densities for the AAI and GEI studies were similar and generally ranged between 1,500 and 10,000 organisms/m2. Numbers of taxa collected ranged between 30 and 42 taxa in the GEI study compared to 22 to 37 taxa for AAI fall study. The number of EPT taxa was similar for the two
Aquatics Associates, Inc. 47 May 2010 Aquatic Monitoring Program for SPCURE, 2008 studies and ranged from 4 to 9 taxa compared to 6 to 9 taxa collected for the AAI study. The HBI values reported by GEI were >5.0 at all sites whereas for the AAI study HBIs were generally between 4.5 and 6.5, with both studies indicating the presence of high numbers of tolerant organisms. Similarly, oligochaete density (presumably mostly tubificid worms) in the GEI study increased notably upstream from Evans Ave. (AAI site S21/22) as reported by AAI for this study.
3.3.2 Rock Basket Samples
Community Characteristics
The benthic macroinvertebrate community that colonized the rock baskets was quite different from that found in the kick samples collected in either the spring or fall seasons. The most notable difference was the paucity of oligochaetes collected by this method (Figure 9, Appendix D). In addition, the only mayfly colonizing the rock baskets to any extent was T. explicatus, while A. insignificans and B. tricaudatus were either entirely absent or when present, found only in low numbers (Table 6, Appendix D). Similar to the mayflies, caddisflies were also low in abundance and the same predominant species (Cheumatopysche sp. and Hydropsyche sp.) collected in kick samples also colonized the rock baskets. Chironomid abundances and numbers of taxa were slightly greater in the rock baskets than in the kick samples. Although the number of macroinvertebrate orders represented in the rock baskets was lower than in the fall kick samples (12 vs. 15 and 17 orders), the number of individual taxa collected was greater in the rock baskets (71 vs. 63 & 66 taxa) largely due to the higher numbers of midge taxa.
In the rock baskets, dipterans were the dominant macroinvertebrate group, followed by turbellarians, amphipods, caddisflies, mayflies, and lastly oligochaetes (Figure 9, Appendix D). As found in the spring and fall kick samples, the dipterans in the rock baskets were comprised mainly of midges although the dominant taxa were different and included Microtendipes sp. and/or Phaenopsectra sp. compared to Cricotopus sp. in the kick samples. In fact, Microtendipes sp., a moderately tolerant species was the dominant taxon at site S76 where it had an abundance of 40.4%. Likewise, Phaenopsectra sp. was nearly the dominant taxon at site N18 with an abundance of 22.4% while the flatworm Dugesia sp. was the dominant taxon at 23.4%. Notably, Dugesia sp. was the dominant taxon in two of the rock basket samples with abundances of 49.6% and 54.2% at sites S30 and S21/22, respectively. Mayflies were only abundant in samples collected at site S76 with a total abundance of 31.1%; otherwise at the other five sites mayflies accounted for only <1% to 10.6% of the macroinvertebrate community with the highest abundance found at site S21/22. Caddisflies were also only abundant at one site, N45/46 where they comprised 49.3% of the entire macroinvertebrate community. At this site, Hydropsyche sp. was the
Aquatics Associates, Inc. 48 May 2010 Aquatic Monitoring Program for SPCURE, 2008 dominant caddisfly species as well as the dominant taxon at 37.8%. Amphipods, similar to the other groups discussed, were also abundant but only at one site, S84 comprising nearly 80% of the macroinvertebrate community. Crangonyx sp. was the most abundant amphipod and the dominant taxon at site S84 with an abundance of 52.7%, while Hyalella azteca was also relatively abundant at 26.3%. Though considerably lower in numbers, amphipods were still relatively abundant at the remaining rock basket sites. Lastly, the abundance of oligochaetes was low (<3.1%) at all sites except at site N45/46 where they comprised 13.7% of the macroinvertebrate population. At this site, each of the three rock basket samplers was somewhat silted in thereby providing more suitable substrate conditions for these worms to colonize. The lack of soft sediment substrates in the rock baskets severely limits the ability of oligochaetes to colonize these artificial samplers, which has also been reported in Maine where rock baskets are used extensively for aquatic monitoring and oligochaetes are only occasional colonizers of rock basket samplers (Meidel 2009). The rock basket data showed a pattern of random variability of the dominant groups collected from site to site (i.e., turbellaria dominant at two sites, amphipods dominant at one site, caddisflies dominant at one site, dipterans dominant at two sites, dipterans and mayflies co- dominant at one site) and indicated no clear upstream/downstream trends in terms of community structure.
Numbers of taxa collected in the rock baskets were similar to the kick samples and ranged from 20 to 38 taxa, with 38 taxa being collected at four of the six sites (sites S30 through N45/46) (Figure 10, Appendix D). Densities were also similar to both the spring and fall kick samples ranging from 1,202 to 12,804 organisms/m2 with the lowest numbers collected at site N18 and the highest at site S76.
Community Metrics
For several key community metrics, the rock basket results contradicted those found in the kick samples especially at the apparently impacted sites S21/22 and N45/46. At these two sites, the lowest HBI value for the rock baskets was found at site S21/22 (HBI 4.91, indicating least impacted site), while the HBI at site N45/46 was 5.56 which was within the values reported for the other sites (Table 9, Figure 11). The highest (worst) HBI was at site S84 (HBI 6.44) due to the predominance of tolerant amphipods collected at this site. ICI scores were actually highest (better) at both sites S21/22 and N45/46 with values of 28 for the rock baskets samples, while the lowest ICI score was 10 at site S84 which was also the lowest ICI reported to date for all sampling types and events. Furthermore, although site S76 appears to be one of the least impacted sites based on the kick sampling results, the ICI score was only 22 for the rock baskets at this site indicating a level of impairment contrary to the kick data. The ICI/HBI ratio was likewise incongruous at sites S21/22 and N45/46 as the highest (better) ratios were noted (5.70 and 5.04,
Aquatics Associates, Inc. 49 May 2010 Aquatic Monitoring Program for SPCURE, 2008 respectively) at these sites, while lowest ratio was at site S84 with a value of 1.55 with site S76 having an ICI/HBI ratio of 4.06.
Only 2 and 3 EPT taxa were collected at sites S84 and S76, which were the two most impacted of the rock basket sites as indicated by the other key metrics (Table 9, Figure 11). Otherwise, the number of EPT taxa at the other four sites (S30 through N45/46) ranged between 6 and 9 taxa as found in the fall kick samples.
There was no correlation between HBI values and % Oligochaeta due to the overall paucity of these worms at all but one of the rock basket sites (N45/46). The % sprawlers was highest at site S76 (32.0%) due to the abundance of the mayfly T. explicatus, with comparatively fewer sprawlers found at the other five sites (6.4 to 9.9%) which was consistent with that found in the kick samples.
3.3.3 Macroinvertebrate Summary
A total of 17 macroinvertebrate major taxonomic groups were collected in the fall kick samples, whereas 12 groups were represented in the spring 2008 and in the fall 2008 rock basket samples. In the kick samples, the most taxa were collected in the fall, with a total of 63 and 66 taxa in 2007 and 2008, respectively, compared to 60 taxa in the spring 2008. Comparatively more taxa were found in the rock basket samples (71 taxa), which was due to higher numbers of midge taxa.
The fall macroinvertebrate communities were dominated by caddisflies in 2007 and by mayflies in 2008 with dipterans also abundant throughout the study reach. In both years, oligochaetes (mainly tubificids) were generally the most abundant group at sites S21/22 and S7 which are downstream from the combined effluent discharges of L/E WWTP and Xcel’s Arapahoe and Zuni plants, and at site N45/46 in 2008. Turbellarians (flatworms) were also well represented at most sites in both years. These non-insects tend to be prolific in areas that are high in organic enrichment. In contrast, the spring community was dominated by the oligochaete, Nais sp. at all six sites which is undoubtedly related to the overall accumulation of organic matter on the substrates that occurs during the winter low flow period in the SPR system. Dipterans were also predominant in the spring and consisted mainly of midges. Mayflies and caddisflies were occasionally abundant at some sites but overall were less numerous in the spring than in the fall, primarily because of their life histories (rather than any anthropogenic perturbations) with these insects either in the egg or very early instar stages at the time of sampling in the spring. Mayflies and caddisflies were represented by the same taxa found in the fall. Amphipods (scuds) were abundant only
Aquatics Associates, Inc. 50 May 2010 Aquatic Monitoring Program for SPCURE, 2008 at site S84 and were generally not collected at any other of the sites. Though present in the spring, turbellarians were considerably less numerous than found in the fall.
The benthic macroinvertebrate community that colonized the rock baskets was markedly different from the spring and fall kick samples. The most notable difference was the paucity of oligochaetes collected by this method, which is mostly due to the lack of soft substrates in the rock baskets that severely limits oligochaete colonization of these samplers. Also fewer mayflies or caddisflies were consistently collected, and chironomid abundance and numbers of taxa were slightly greater in the rock baskets than in the kick samples. Overall, community structure was highly variable in the rock baskets in that almost every site was dominated by a different macroinvertebrate group with no apparent upstream/downstream trends.
The metrics calculated that were most responsive to the main environmental stressors were the HBI, ICI, ICI/HBI ratio, % Oligochaeta, and % sprawlers. Relatively few EPT taxa were collected in both spring (4 to 6 taxa) and fall (6 to 9 taxa). Although EPT taxa are sensitive to environmental conditions, too few were collected and there was so little variability among the sites that detection of any impairment differences was not possible with this metric. In the fall of both sampling years, both the HBI and % Oligochaeta responded similarly (both increased) at sites S21/22 and S7. An abrupt increase in both years in % Oligochaeta at sites S21/22 and S7 coincided with increases in the HBI values which were highest (worse) at these sites. HBI values were comparatively lower (better) at sites upstream and downstream from sites S21/22 and S7. In addition, the ICI scores at these two sites were either at or near their lowest (also worse) compared to most of the other sites. Overall, the fall ICI scores were slightly more depressed in 2008 than in 2007 with the greatest decrease noted at site S76. Regardless of the lower ICIs often observed in the fall, macroinvertebrate condition was rated as fair at all sites in both 2007 and 2008, except at site S76 which was rated as good in 2007. The ICI/HBI ratio appears to better discriminate levels of impairment among sites than does either metric alone. Lower ICI/HBI ratios were recorded at sites S21/22, S7, and N45/46 in both years and at sites N4 and N34 in 2008. The lowest ratios were noted at site S7 in both 2007 and 2008. The consistently lower ICI/HBI ratio reported for site N45/46 indicates the benthic community was more stressed than most of the remaining sites. While this site is not located immediately downstream from any effluent discharges, it is situated downstream from major storm water outfalls that drain this industrialized area with shifting sand substrates also predominant in this reach, both of which likely limit the macroinvertebrate community.
The metrics calculated for the spring 2008 were reflective of high abundances of the tolerant oligochaete, Nais sp. found at all spring sites. HBI values were notably higher and ICIs were lower than those
Aquatics Associates, Inc. 51 May 2010 Aquatic Monitoring Program for SPCURE, 2008 recorded for both fall collections indicating that all sites in the spring were highly stressed by organic enrichment. The highest HBI was recorded at site S21/22, while second highest HBI was at site N45/46 further indicating that these two sites are more stressed than most of the other SPR sites. The spring ICIs were also lowest at sites S21/22 and N45/46, however all scores were still in the fair category. While all ICI/HBI ratios were comparatively lower in the spring than in fall, the lowest ratios were again at sites S21/22 and N45/46. The % Oligochaetes was relatively high at all sites in the spring although the substantial increases evident in fall at sites S21/22 and N45/46 were not as pronounced in the spring. The distribution of sprawlers was similar in the spring and fall with generally fewer sprawlers collected at site S30 and the remaining downstream sites.
Metrics for the rock basket samples contradicted the results for the kick samples, especially at the previously mentioned impacted sites S21/22 and N45/46, confounding the 2007-2008 macroinvertebrate study results. The lowest HBI (best) for the rock baskets was reported at site S21/22 indicating it was the least impacted site, and the HBI at site N45/46 was higher but still within the range of values reported for the other sites. ICIs were also highest (better) at both sites S21/22 and N45/46 which is inconsistent with the kick results. The ICI/HBI ratio was also incongruously highest (better) at sites S21/22 and N45/46 further indicating low impairment at these two sites. Metrics for the rock baskets instead show that site S84 was the most impaired, as this site had fewest EPT taxa, the highest HBI, and lowest ICI due to the overwhelming abundance of tolerant amphipods. Furthermore, the comparatively low ICI reported for site S76 was also contrary to the kick ICIs which suggest this was one of the least impacted sites.
Aquatics Associates, Inc. 52 May 2010 Aquatic Monitoring Program for SPCURE, 2008
4.0 REFERENCES
Aquatics Associates, Inc. 2002. Results of the Aquatic Monitoring Program in Big Dry Creek and Walnut Creek, 1999-2001. Prepared for the Cities of Broomfield, Northglenn, and Westminster, Colorado.
Aquatics Associates, Inc. 2005. Results of the Aquatic Monitoring Program in Big Dry Creek, 2004. Prepared for the Cities of Broomfield, Northglenn, and Westminster, Colorado.
Aquatics Associates, Inc. 2007. Results of the Aquatic Monitoring Program in Big Dry Creek, 2006. Prepared for the Cities of Broomfield, Northglenn, and Westminster, Colorado.
Barbour, M.T., J. Gerritsen, B.D. Snyder, and J.B. Stribling. 1999. Rapid bioassessment protocols for use in streams and wadeable rivers: periphyton, benthic macroinvertebrates and fish, second edition. EPA 841-B-99-002. U.S. Environmental Protection Agency, Office of Water, Washington, D.C.
Beckman, W. C. 1952. Guide to the fishes of Colorado. University of Colorado Museum. Leaflet No. 11. Boulder, Colorado. 110 pp.
Belsile, N., Y. Chen, J.M. Gunn, J. Tong, Y. Alarie, T. Delonchamp, and C. Lang. 2006. The effects of selenium on mercury assimilation by freshwater organisms. Canadian Journal of Fisheries and Aquatic Sciences 63:1-10.
Bramblett, R.G. and K.D. Fausch. 1991. Variable fish communities and the Index of Biotic Integrity in a western Great Plains River. Transactions of the American Fisheries Society 120:752-769.
Bramblett, R.G., T.R. Johnson, A.V. Vale, and D.G. Heggem. 2005. Development and evaluation of a fish assemblage index if biotic integrity for northwestern Great Plains streams. Transactions of the American Fisheries Society 134:624-640.
Brinkman, S. 2004. Personal communication regarding conversion of fish tissue data from wet weight to dry weight. Colorado Division of Wildlife, Fort Collins, Colorado.
Brown and Caldwell. 2003. Selenium stakeholders 2002 comprehensive data analysis technical memorandum. Prepared for Colorado Department of Public Health and Environment/Water Quality Control Division, Colorado Division of Wildlife, U.S. Fish and Wildlife Service, and U.S. Environmental Protection Agency Region 8. 55 pgs, plus appendices.
Colorado Division of Wildlife. 2007. List of State and Federal endangered, threatened, and special concern wildlife, October 15, 2007. Colorado Division of Wildlife, Denver, CO.
Colorado Division of Wildlife. 2008. Stocking records for Chatfield and Cherry Creek Reservoirs 2006- 2008. Colorado Division of Wildlife, Denver, CO.
Colorado Water Quality Control Commission. 2009a. Regulation No. 38 Classifications and Numeric Standards South Platte River Basin, Laramie River Basin, Republican River Basin, Smoky Hill River Basin. 5 CCR 1002-38. Subsection 38.74 Statement of Basin Specific Statutory Authority and Purpose, June 8-9, 2009 Rulemaking hearing regarding deleting Segment 6c and adding to Segment 14 as proposed by Centennial Water and Sanitation District.
Aquatics Associates, Inc. 53 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Colorado Water Quality Control Commission. 2009b. Regulation No. 38 Classifications and Numeric Standards South Platte River Basin, Laramie River Basin, Republican River Basin, Smoky Hill River Basin. 5 CCR 1002-38. Subsection 38.74 Statement of Basin Specific Statutory Authority and Purpose, June 8-9, 2009 Rulemaking hearing regarding a temporary modification to selenium standard in Segment 14 as proposed by Public Service Company of Colorado.
Colorado Water Quality Control Commission. 2009c. Regulation No. 38 Classifications and Numeric Standards South Platte River Basin, Laramie River Basin, Republican River Basin, Smoky Hill River Basin. 5 CCR 1002-38. Subsection 38.74 Statement of Basin Specific Statutory Authority and Purpose, June 8-9, 2009 Rulemaking hearing regarding temperature standard in Segment 14 proposed by Colorado Water Quality Control Division.
Colorado Water Quality Control Commission. 2009d. Regulation No. 38 Classifications and Numeric Standards South Platte River Basin, Laramie River Basin, Republican River Basin, Smoky Hill River Basin. 5 CCR 1002-38. Subsection 38.74 Statement of Basin Specific Statutory Authority and Purpose, June 8-9, 2009 Rulemaking hearing regarding temperature standard in Segment 14 proposed by Littleton/Englewood Wastewater Treatment Plant.
Colorado Water Quality Control Division. 2009. Standards Framework Workgroup Meeting Summary, January 15, 2009. Metals and temperature criteria. Electronic Memo.
Colorado Water Quality Forum. 1995. A guide for water quality monitoring in Colorado. Draft, June 1995. Standard operating procedures for the collection and processing of benthic invertebrate samples.
DeForest, D. K., K.V. Brix, and W.J. Adams. 1999. Critical review of proposed residue-based selenium toxicity based thresholds for freshwater fish. Human Ecological Risk Assessment Management 5(6):1187-1228.
Denver Department of Environmental Health. 2005. 2003 Water quality assessment report, Volume III: Biomonitoring. Denver Department of Environmental Health, Division of Environmental Quality. December 2005. 28 pgs, plus appendices.
DeShon, J. E. 1995. Development and applications of the invertebrate community index (ICI). Pages 217-243 In Davis, W. S. and T. Simon (eds.), Biological assessment and criteria: tools for water resource planning and decision making. Lewis Publishers, Boca Raton, Florida.
GEI Consultants, Inc. 2008. Evaluation of potential approaches to expected condition in the urbanized South Platte River, Colorado. May 2008. Report prepared for South Platte Coalition for Urban River Evaluation.
Hillwalker, W.E., P.C. Jepson, and K.A. Anderson. 2006. Selenium accumulation patterns in lotic and lentic aquatic systems. Science of the Total Environment 366:367-379.
Hoffman, G.L. 1999. Parasites of North American fishes. Second edition. Cornell University Press, Ithaca, New York.
Hynes, H.B.N. 1972. The ecology of running waters. University of Toronto Press, Toronto, Canada.
Hynes, H.B.N. 1971. The biology of polluted waters. University of Toronto Press, Toronto, Canada.
Karr, J. R. 1981. Assessment of biological integrity using fish communities. Fisheries 6(6):21-27.
Aquatics Associates, Inc. 54 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Karr, J. R., K. D. Fausch, P. L. Angermeier, P. R. Yant, and I. J. Schlosser. 1986. Assessing biological integrity in running waters: a method and its rationale. Illinois Natural History Survey, Special Publication 5. Illinois Natural History Survey, Champaign, Illinois. 28 pp.
Klemm, D.J., P.A. Lewis, F. Fulk, and J.M. Lazorchak. 1990. Field and laboratory methods for evaluating the integrity of surface waters. EPA/600/4-90/030. U.S. Environmental Protection Agency, Cincinnati, Ohio.
Kondratieff, F.P., R.A. Mathews, and A.L. Buikema Jr. 1984. A stressed stream ecosystem: Macroinvertebrate community integrity and microbial trophic structure. Hydrobiologia 111:81- 91.
Lemly, A.D. 1993. Teratogenic effects of selenium in natural populations of freshwater fish. Ecotoxicolgy and Environmental Safety 26:181-204.
Lemly, D.A. 1998. Pathology of selenium poisoning in fish. U.S. Forest Service, Blacksburg, VA. p. 281-296.
May, T,W., J.F. Fairchild, J.D. Petty, M.J. Walther, J. Lucero, M. Delvaux, J. Manring, and M. Armbruster. 2008. An evaluation of selenium concentrations in water, sediments, invertebrates, and fish from the Solomon River Basin. Environmental Monitoring and Assessment 137:213-232.
May, T.W., M.J. Walther, J.D. Petty, J.F. Fairchild, J. Lucero, M. Delvaux, J. Manring, M. Armbruster, and D. Hartman. 2001. An evaluation of selenium concentrations in water, sediment, invertebrates, and fish in the Republican River Basin: 1997-1999. Environmental Monitoring and Assessment 72: 179-206.
Meidel, S. 2009. Personal communication regarding rock basket sampling results for streams in Maine. Maine Department of Environmental Protection, Biological Monitoring Unit, Augusta, ME.
Merritt, R. W., K. W. Cummins, and M. B. Berg (eds). 2008. An introduction to the aquatic insects of North America, fourth edition. Kendall/Hunt Publishing Company, Dubuque, Iowa.
Nessler, T. P., R. VanBuren, J. A. Stafford, and M. Jones. 1997. Inventory and status of South Platte River native fishes in Colorado. Final report, June 1997. Aquatic Wildlife Section, Colorado Division of Wildlife, Fort Collins, Colorado.
Orr, P.L., K.R. Guiguer, and C.K. Russel. 2006. Food chain transfer of selenium in lentic and lotic habitats of a western Canadian watershed. Ecotoxicology and Environmental Safety 63:175-188.
Paul, M.J., J. Gerritsen, C. Hawkins, and E. Leppo. 2005. Development of biological assessment tools for Colorado. October 2005. Draft report prepared for Colorado Department of Health, Water Quality Control Division, Monitoring Unit, Denver, CO.
Pennak, R.W. 1978. Fresh-water invertebrates of the United States, 2nd Edition. John Wiley and Sons, New York, 803 p.
Plafkin, J.L., M.T. Barbour, K.D. Porter, S.K. Gross, and R.M. Hughes. 1989. Rapid bioassessment protocols for use in streams and rivers: benthic macroinvertebrates and fish. EPA/444/4-89-001. U.S. Environmental Protection Agency, Washington, D.C.
Aquatics Associates, Inc. 55 May 2010 Aquatic Monitoring Program for SPCURE, 2008
Propst, D. 1982. Warmwater fishes of the Platte River basin, Colorado: distribution, ecology, and community dynamics. Ph. D. Dissertation. Colorado State University, Fort Collins, Colorado. 283 p.
Rosenberg, D. M. and V. H. Resh. 1982. Use of artificial substrates in the study of freshwater macroinvertebrates. In Artificial Substrates, John Cairns, Jr. (ed.), p.175-235. Ann Arbor Science Publications, Inc., Ann Arbor, MI.
Schrader, L.H. 1989. Use of the index of biotic integrity to evaluate fish communities in western Great Plains streams. Master’s Thesis, Dept. of Fishery and Wildlife Biology, Colorado State University, 120 p.
Simmons, D.B.D. and D. Wallschlager. 2005. A critical review of the biogeochemistry and ecotoxicology of selenium in lotic and lentic environments. Environmental Toxicology and Chemistry, Vol. 24, No. 6, pp. 1331-1343.
Sprague, L. A., R.E. Zuellig, and J.A. Dupree. 2006. Effects of urbanization on stream ecosystems in the South Platte River Basin, Colorado and Wyoming. U.S. Geological Survey Scientific Investigations Report 2006-5101-A, 141p.
U.S. Environmental Protection Agency. 2004. Draft aquatic life criteria for selenium – 2004. Office of Water, Office of Science and Technology, Washington D.C.
Voelz, N.J., R.E. Zuellig, S. Shieh, and J.V. Ward. 2005. The effects of urban areas on benthic macroinvertebrates in two Colorado plains rivers. Environmental Monitoring and Assessment 101:175-202.
Walker, P. 2004. Personal communication. Fish Pathologist, Colorado Division of Wildlife, Aquatic Animal Health Laboratory, Brush, Colorado.
Woodling, J. 1985. Colorado’s little fish. A guide to the minnows and other lesser known fishes in the State of Colorado. Colorado Division of Wildlife, Denver, Colorado. 77 pp.
Wright Water Engineers, Inc. 2007. Exploration of Potential Selenium Sources in the Big Dry Creek Watershed (Revised). Memorandum to Big Dry Creek Watershed Association Board of Directors. December 1, 2006 (updated October 4, 2007).
Zuellig, R.E., J.F. Bruce, E. E. Evans, and R. Stogner. 2007. Urban-related environmental variables and their relation with patterns in biological community structure in the Fountain Creek basin, Colorado, 2003-2005. U.S. Department of the Interior, U.S. Geological Survey, Scientific Publications Report 2007-5225.
Zuellig, R.E. 2001. Macroinvertebrate and fish communities along the Front Range of Colorado and their relationship to habitat in the urban environment. Thesis. Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, Colorado.
Aquatics Associates, Inc. 56 May 2010
APPENDIX A
PHOTOGRAPHIC DOCUMENTATION
Site S84 – Oct 2007 Kick sampling in riffle upstream from Marcys Gulch Site S84 – Oct 2007 Glide habitat upstream from Marcys Gulch
Site S76 – Oct 2007 Riffle habitat downstream from Mineral Ave. at Site S76 – Oct 2008 View of study reach downstream from Mineral Ave. at Carson Nature Center Carson Nature Center
Site S62 – Oct 2007 Study reach upstream from Hudson Gardens Site S34 – Oct 2007 Study reach downstream from Hampden Ave. and Bear Creek
Site S51 – Oct 2007 Kick sampling in glide habitat upstream from Site S51 – Oct 2008 View of entire study reach downstream from Union Ave. footbridge and Union Ave.
Site S30 – Oct 2008 Kick sampling in riffle downstream from Dartmouth Ave., Site S30 – Oct 2008 Glide habitat in reach immediately upstream from immediately upstream from Littleton/Englewood WWTP and Xcel’s Arapahoe Littleton/Englewood WWTP and Xcel Arapahoe plant outfalls plant
Site S21/22 – Oct 2008 Electrofishing in reach upstream from Evans Ave., Site S21/22 – Oct 2008 View of entire reach upstream from Evans Ave., immediately downstream from Littleton/Englewood WWTP and Xcel’s immediately downstream from Littleton/Englewood WWTP and Xcel’s Arapahoe plant Arapahoe plant
Site S7 – Oct 2007 Reach downstream from Mississippi Ave. and Sante Fe Site N4 – Oct 2007 Glide habitat in reach upstream from 6th Ave. and overpass, upstream from Xcel’s Zuni Plant Xcel’s Zuni Plant
Site N18 – Oct 2008 View of entire reach at Elitch’s, downstream from I-25 Site N18 – Oct 2008 View of reach at Elitch’s, downstream from I-25 during and Xcel’s Zuni Plant the fish sampling event
Site N28 – Oct 2007 Kick sampling in reach ~0.25 mi. downstream from Site N34 – Oct 2007 Reach downstream from Park Ave. bridge Cherry Creek confluence
Site N45/46 – Oct 2007 Kick sampling in riffle downstream from I-70 Site N45/46 – Oct 2007 Glide habitat sampled upstream from I-70
Site N34 – Oct 2008 Riffle habitat where numerous longnose dace were Site N34 – Oct 2008 Electrofishing in reach downstream from Park Ave. collected in the study reach just downstream from Park Ave. overpass
Site N34 – Oct 2008 Upstream view of reach just downstream from Site N34 – Oct 2008 Upstream view of reach just downstream from Park Ave. overpass, downstream from Cherry Creek Park Ave. overpass
Site N47 – Oct 2008 Upper portion of study reach downstream from I-70, Site N47 – Oct 2008 Electrofishing deep holes by old livestock bridge near the end of Segment 14 upstream from the Burlington Ditch where numerous large carp were collected
Site N47 – Oct 2008 Downstream portion of reach, downstream from I-70 Site N47 – Oct 2008 View looking downstream at site N47 near old livestock bridge
Site N47 – Oct 2008 Fish processing at site N47 downstream from I-70 Site N47 – Oct 2008 Fish processing at site N47
Site S21/22 – Oct 2008 Kick sampling upstream from Evans Ave.
Site S21/22 – Oct 2008 Rock basket samplers in glide habitat Site S21/22 – Oct 2008 Retrieving the rock basket samplers
Site N45/46 Oct 2008 – Rock basket samplers in glide upstream from I-70
APPENDIX B
FISH POPULATION DATA
FISH POPULATION DATA SUMMARY FALL 2008 SOUTH PLATTE RIVER
SPCURE - LIST OF FISH SPECIES COLLECTED scientific name common name
CLUPEIDAE (herrings) Dorosoma cepedianum Gizzard Shad
CYPRINIDAE (carps & minnows) Rhinichthys cataractae Longnose Dace Semotilus atromaculatus Creek Chub Pimephales promelas Fathead Minnow Cyprinus carpio Common Carp Notemigonus crysoleucas Golden Shiner
CATOSTOMIDAE (suckers) Catostomus commersoni White Sucker Catostomus catostomus Longnose Sucker
SALMONIDAE (trouts) Oncorhynchus mykiss Rainbow Trout O. mykiss x O. clarki Rainbow x Cutthroat Hybrid Salmo trutta Brown Trout
POECILIIDAE (livebearers) Gambusia affinis Mosquitofish
GASTEROSTEIDAE (sticklebacks) Culaea inconstans Brook Stickleback
CENTRARCHIDAE (sunfishes) Lepomis cyanellus Green Sunfish Micropterus dolomieu Smallmouth Bass Micropterus salmoides Largemouth Bass Lepomis macrochirus Bluegill Pomoxis nigromaculatus Black Crappie
PERCIDAE (perches) Etheostoma nigrum Johnny Darter Etheostoma exile * Iowa Darter Perca flavescens Yellow Perch Stizostedion vitreum Walleye
Bold indicates native to South Platte River. * Listed as State Special Concern (not a statutory category) by CDOW, last updated 10/15/07. FISH POPULATION DATA SUMMARY FALL 2008 SOUTH PLATTE RIVER
RELATIVE ABUNDANCE
S84 S76 S51 S30 S21/22 N18 N34 N47 White Sucker 99.3 77.0 79.3 81.4 70.7 25.1 12.4 26.2 Longnose Sucker 0.4 0.2 1.7 0.4 Longnose Dace 0.1 0.8 7.1 2.1 7.3 0.2 51.6 3.5 Creek Chub 0.2 5.7 9.3 5.9 27.4 5.9 4.8 Fathead Minnow 6.2 2.0 4.2 38.2 22.2 58.8 Common Carp 0.2 0.6 2.6 3.6 Golden Shiner 0.1 0.3 Green Sunfish 6.6 0.2 0.5 4.2 0.5 0.2 0.1 Smallmouth Bass <0.1 6.5 1.1 2.7 2.2 1.1 0.5 0.4 Largemouth Bass 0.4 2.7 0.2 0.4 3.6 1.0 0.9 0.5 Bluegill 0.1 0.1 Black Crappie <0.1 0.1 0.2 0.1 <0.1 Johnny Darter 0.1 1.1 1.4 5.8 1.1 1.0 Iowa Darter 4.7 Yellow Perch 0.1 0.5 Walleye 0.2 0.1 Brook Stickleback <0.1 0.2 0.1 Gizzard Shad 0.1 Mosquitofish <0.1 Rainbow Trout <0.1 0.8 Rainbow x Cutthroat Hybrid <0.1 Brown Trout 0.3
NUMBER COLLECTED
S84 S76 S51 S30 S21/22 N18 N34 N47 White Sucker 4650 1026 1684 909 253 443 217 526 Longnose Sucker 5 4 30 9 Longnose Dace 7 10 151 24 26 4 906 71 Creek Chub 2 122 104 21 484 103 97 Fathead Minnow 131 22 15 674 390 1178 Common Carp 2 2 46 73 Golden Shiner 26 Green Sunfish 88 5 6 15 9 4 2 Smallmouth Bass 1 86 23 30 8 20 8 9 Largemouth Bass 21 36 5 5 13 18 16 10 Bluegill 1 1 Black Crappie 1 1 4 1 1 Johnny Darter 2 12 5 103 19 20 Iowa Darter 62 Yellow Perch 18 Walleye 32 Brook Stickleback 1 2 1 Gizzard Shad 1 Mosquitofish 1 Rainbow Trout 1 11 Rainbow x Cutthroat Hybrid 1 Brown Trout 4
Total Collected 4683 1332 2124 1117 358 1764 1755 2004 Total Species Collected 8 11 9 12 9 11 16 13 Native Species 37676787
APPENDIX C
FISH TISSUE MERCURY AND SELENIUM DATA
SPCURE - SUMMARY OF ANALYTICAL RESULTS WHOLE BODY MERCURY (Hg) AND SELENIUM (Se) CONCENTRATIONS IN FISH SOUTH PLATTE RIVER - FALL 2008
Selenium Results (u g/g, dry wt.) Species trophic/habit S84 S76 S51 S30 S21/22 N18 N34 N47
WHS 1/ o/b 2/ HgUUUUU0.25 * U U Se 1.8 2.2 2.3 3.0 3.2 4.8 5.8 5.6
CPP o/b Hg U -- -- U U -- 0.2 * U Se 1.9 -- -- 7.3 10.5 -- 7.1 4.3
CRC o/b Hg ------U -- -- Se ------5.5 -- --
FMW o/wc Hg -- -- UUUU U U Se -- -- 4.5 5.1 4.4 5.8 5.3 6.3
SNF o/wc Hg -- U ------Se -- 5.0 ------
LNDi/bHg--UUUUU U U Se -- 4.3 5.8 8.7 10.0 10.2 9.0 14.5
SMBp Hg--UUUUUU U Se -- 2.3 3.5 4.5 5.4 5.6 6.2 4.8
LMB p Hg U ------Se 4.4 ------
Samples analyzed by ACZ Laboratories, Steamboat Springs, CO. u g/g = ppm (micrograms per gram = parts per million). U = less than method detection limit. * indicates lab estimate: Hg value detected between MDL (method detection limit) and PQL (practical quantitation limit).
1/ Abbrevations for fish species are: white suckers (WHS), common carp (CPP), creek chub (CRC), fathead minnow (FMW), green sunfish (SNF), longnose dace (LND), smallmouth bass (SMB), and largemouth bass (LMB). 2/ Abbreviations for trophic and habit designations are: omnivore/bottom (o/b), omnivore/water column (o/wc), insectivore/bottom (i/b), and piscivore (p).
APPENDIX D
MACROINVERTEBRATE COMMUNITY DATA
SPCURE - LIST OF MACOINVERTEBRATE SPECIES AND THEIR OCCURRENCE SOUTH PLATTE RIVER 2007-2008
Fall Spring Rock Baskets Ta1on 2007 2008 2008 2008 TURBELLARIA Planariidae Dugesia sp. x x x x NEMERTEA Prostoma sp. x x x NEMATODA x OLIGOCHAETA Enchytraeidae x x x x Lumbricidae x x x Lumbriculidae x x x x Naididae x Chaetogaster sp. x x x x Dero sp. x x Nais sp. x x x x Ophidonais serpentina x x x Pristina sp. x x Slavina appendiculata x x Stylaria lacustris x Tubificidae Tubificidae with hair chaetae x x x x Tubificidae without hair chaetae x x x x HIRUDINEA Erpobdellidae x x Erpobdella punctata x Glossiphoniidae Helobdella stagnalis x ISOPODA Asellidae Caecidotea sp. x x x x AMPHIPODA Gammaridae Crangonyx sp. x x x x Hyalellidae Hyalella azteca x x x x DECAPODA Cambaridae Orconectes sp. x x x x ACARI Hygrobatidae Hygrobates sp. x Sperchonidae Sperchon sp. x x x EPHEMEROPTERA Baetidae Acentrella insignificans x x x x Baetis flavistriga x x x Baetis tricaudatus x x x x Fallceon quilleri x x x Paracloeodes minutus x Leptohyphidae Tricorythodes explicatus x x x x ODONATA Aeshnidae Aeshna sp. x Calopterygidae Hetaerina americana x Coenagrionidae x Argia sp. x Gomphidae Ophiogomphus severus x x
Aquatics Associates, Inc. March 2009 SPCURE - LIST OF MACOINVERTEBRATE SPECIES AND THEIR OCCURRENCE SOUTH PLATTE RIVER 2007-2008
Fall Spring Rock Baskets Ta1on 2007 2008 2008 2008 HEMIPTERA Corixidae x x Sigara alternata x Sigara grossolineata x Veliidae Microvelia sp. x x TRICHOPTERA Hydropsychidae Cheumatopsyche sp. x x x x Hydropsyche sp. x x x x Hydroptilidae Hydroptila sp. x x x x Leucotrichia pictipes x Leptoceridae Oecetis sp. x x x Psychomyiidae Psychomyia flavida x x LEPIDOPTERA Pyralidae Petrophila sp. x x DIPTERA Ceratopogonidae Ceratopogoninae x x x x Chironomidae Brillia sp. x x x Cardiocladius sp. x x x Chironomus sp. x x x x Cladotanytarsus sp. x x Cricotopus sp. x x x x Cricotopus/Orthocladius sp. x Cricotopus trifascia group x x x x Cryptochironomus sp. x x x x Diamesa sp. x x Dicrotendipes sp. x x x x Eukiefferiella sp. x x x x Hydrobaenus sp. x x x Limnophyes sp. x x Micropsectra sp. x x x x Microtendipes sp. x x x x Nanocladius sp. x x Odontomesa sp. x x x Orthocladius sp. x x x x Pagastia sp. x Paracladopelma sp. x x Parakiefferiella sp. x x x x Parametriocnemus sp. x x x Paraphaenocladius sp. x Paratanytarsus sp. x Phaenopsectra sp. x x x x Polypedilum sp. x x x x Procladius sp. x Pseudochironomus sp. x x x x Pseudodiamesa sp. x Pseudosmittia sp. x Radotanypus sp. x Rheocricotopus sp. x x x x Rheotanytarsus sp. x x Saetheria tylus x x x x Stictochironomus sp. x x x x Thienemanniella sp. x x x Thienemannimyia group x x x x Tvetenia sp. x
Aquatics Associates, Inc. March 2009 SPCURE - LIST OF MACOINVERTEBRATE SPECIES AND THEIR OCCURRENCE SOUTH PLATTE RIVER 2007-2008
Fall Spring Rock Baskets Ta1on 2007 2008 2008 2008 Empididae Hemerodromia sp. x x x Neoplasta sp. x x x Muscidae Lispoides aequifrons x Psychodidae Pericoma/Telmatoscopus sp. x Simuliidae Simulium sp. x x x x Stratiomyidae Caloparyphus sp. x x Tipulidae x x Tipula sp. x x x GASTROPODA Ancylidae Ferrissia sp. x x Physidae x x BIVALVIA Corbiculidae Corbicula fluminea x x x x Sphaeriidae Pisidium sp. x
Total Number of Taxa 63 66 60 71 Range of Taxa - all sites 22-37 25-35 24-33 20-38
Aquatics Associates, Inc. March 2009 SPCURE - PREDOMINANT AND IMPORTANT MACOINVERTEBRATE SPECIES AND THEIR OCCURRENCE SOUTH PLATTE RIVER Fall 2007 - Kicks * Taxa S84 S76 S62 S51 S34 S30 S21/22 S7 N4 N18 N28 N34 N45/46 TURBELLARIA Dugesia sp. 7.4 0.5 5.6 11.9 5.0 3.9 7.2 7.5 24.8 5.1 1.8 2.6 2.0 803 75 473 1005 233 293 311 435 765 285 68 100 30
OLIGOCHAETA Enchytraeidae 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4.0 00000000000059
Nais sp. 0.4 2.3 1.8 1.0 3.9 12.6 3.4 9.2 4.3 9.7 7.8 2.0 3.6 45 345 150 83 180 953 146 533 131 548 293 78 54
Tubificidae 0.8 0.7 0.2 0.2 2.8 5.2 28.4 30.7 1.3 3.6 3.4 9.6 9.8 83 105 15 15 128 398 1226 1778 39 203 128 375 144
AMPHIPODA Crangonyx sp. 1.6 0.0 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 173000800000000
Hyalella azteca 0.3 0.0 0.0 0.0 0.0 0.4 0.1 0.0 0.0 0.0 0.8 0.2 0.0 300 0 0 0304 0 0 0308 0
EPHEMEROPTERA Acenetrella insignificans 1.7 9.7 9.9 13.9 15.4 4.7 3.2 7.1 30.2 22.6 20.4 18.9 19.4 188 1455 840 1170 716 353 139 413 920 1275 761 738 286
Baetis tricaudatus 0.1 0.9 5.5 6.9 6.5 6.7 3.7 7.1 3.4 4.3 1.3 2.2 0.7 15 135 465 578 300 510 161 413 104 240 49 88 10
Tricorythodes explicatus 45.2 21.8 9.7 23.3 6.7 9.4 1.1 0.4 0.6 0.5 0.4 0.2 1.1 4928 3270 825 1965 311 713 49 23 18 30 15 8 17
TRICHOPTERA Cheumatopsyche sp. 23.1 22.9 15.8 10.0 3.6 5.8 0.5 0.0 0.0 1.1 0.8 1.9 0.3 2520 3428 1343 840 165 443 23 0 0 60 30 73 5
Hydropsyche sp. 0.3 31.5 36.6 16.7 47.1 23.3 42.8 21.9 20.6 23.4 41.4 45.4 34.2 38 4718 3105 1403 2186 1770 1853 1268 629 1320 1545 1773 505
DIPTERA CHIRONOMIDAE Cricotopus sp. 4.9 2.0 6.7 2.0 2.3 8.4 1.6 8.6 7.4 20.9 13.8 11.2 13.6 533 293 570 165 105 638 68 495 233 1178 514 438 201
Microtendipes sp. 3.1 1.0 2.2 4.8 1.1 8.4 1.8 3.6 1.1 1.7 0.3 0.3 0.0 338 143 188 405 53 638 79 210 33 98 11 10 0
EMPIDIDAE Hemerodromia sp. 1.1 3.1 2.7 2.6 0.7 0.7 0.5 0.4 0.1 0.1 0.9 0.3 0.6 120 465 233 218 34 53 23 23 2 8 34 13 9
* Percent abundance = black; density (organisms/m2) = blue. SPCURE - PREDOMINANT AND IMPORTANT MACOINVERTEBRATE SPECIES AND THEIR OCCURRENCE SOUTH PLATTE RIVER Fall 2008 - Kicks * Taxa S84 S76 S62 S51 S34 S30 S21/22 S7 N4 N18 N28 N34 N45/46 TURBELLARIA Dugesia sp. 1.1 8.5 9.1 11.1 29.1 7.0 24.9 22.0 14.7 1.3 0.2 2.4 23.0 51 503 900 870 1173 368 1778 1170 213 120 3 75 855
OLIGOCHAETA Enchytraeidae 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.5 12.1 2.6 13.3 0 0 0 0 0 0 0 0 0 45 176 79 495
Tubificidae 0.1 0.3 0.0 0.8 0.7 0.9 13.4 33.7 16.1 0.7 1.4 5.6 11.8 3 15 0 60 30 49 960 1793 233 60 20 173 439
AMPHIPODA Crangonyx sp. 5.1 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.2 0.1 0.2 0.0 0.0 247000088038300
EPHEMEROPTERA Acenetrella insignificans 0.8 3.2 4.8 4.5 5.4 11.0 2.5 7.3 13.7 16.8 34.4 12.2 12.8 38 188 480 353 218 578 180 390 199 1515 503 375 476
Baetis tricaudatus 0.2 0.9 5.9 5.9 22.0 29.5 16.8 8.2 7.5 26.4 9.8 10.4 8.0 8 53 585 465 888 1545 1196 435 109 2378 143 321 296
Tricorythodes explicatus 5.2 51.3 55.4 54.0 18.2 7.9 4.1 9.4 16.3 2.2 3.1 1.2 1.6 250 3038 5490 4245 733 416 293 503 236 195 45 36 60
TRICHOPTERA Cheumatopsyche sp. 61.5 5.7 5.8 5.4 2.1 3.4 0.8 0.4 0.0 0.0 0.1 0.8 0.7 2971 338 570 428 85 176 60 23 0 0 2 24 26
Hydropsyche sp. 0.2 8.1 3.2 3.0 5.2 12.6 15.9 0.4 1.0 7.0 2.3 11.5 15.4 8 480 315 233 210 660 1133 23 15 630 33 354 570
DIPTERA CHIRONOMIDAE Cricotopus sp. 13.2 4.1 2.7 3.1 9.2 8.5 5.4 6.5 13.7 15.0 20.8 22.1 6.4 638 240 270 240 373 443 386 345 198 1350 303 681 236
Microtendipes sp. 0.2 9.0 4.8 3.7 2.6 5.5 3.4 0.1 1.0 2.6 0.3 0.4 0.0 8 533 480 293 105 289 240 8 15 233 4 11 0
Orthocladius sp. 1.6 0.8 0.8 0.8 0.4 2.0 0.1 0.1 1.9 3.8 3.4 4.8 2.1 75 45 83 60 18 105 8 8 27 345 50 148 79
Saetheria tylus 0.0 0.0 0.0 0.0 0.1 0.1 0.0 1.1 0.3 3.4 3.3 13.3 0.2 0 0 0 0 5 4 0 60 4 308 49 411 8
SIMULIIDAE Simulium sp. 2.5 0.6 3.0 0.6 1.5 1.9 1.4 3.0 1.6 16.2 2.5 3.2 0.0 120 38 293 45 60 101 98 158 23 1455 36 99 0
* Percent abundance = black; density (organisms/m2) = blue. SPCURE - PREDOMINANT AND IMPORTANT MACOINVERTEBRATE SPECIES AND THEIR OCCURRENCE SOUTH PLATTE RIVER Spring 2008 - Kicks * Taxa S84 S76 S30 S21/22 N18 N45/46 OLIGOCHAETA Enchytraeidae 0.0 0.6 0.0 0.1 4.9 18.3 0 15 0 5 214 600
Nais sp. 40.9 57.3 47.3 68.0 31.0 29.6 733 1575 2925 2668 1365 970
Tubificidae 0.5 0.4 1.1 5.7 0.3 3.4 9 11 68 223 15 110
AMPHIPODA Crangonyx sp. 5.8 0.3 0.0 0.0 0.0 0.0 10380000
EPHEMEROPTERA Baetis tricaudatus 0.0 0.8 23.4 2.6 12.4 3.8 0 23 1448 103 548 125
Tricorythodes explicatus 0.9 18.1 1.9 0.1 0.0 0.0 17 499 120 3 0 0
TRICHOPTERA Hydropsyche sp. 0.1 2.3 2.1 1.0 3.8 4.8 2 64 128 40 165 158
DIPTERA CHIRONOMIDAE Cricotopus sp. 6.8 12.3 18.0 15.9 42.3 34.5 122 338 1110 625 1860 1133
Orthocladius sp. 8.2 0.3 0.2 0.5 0.5 0.3 146815202310
* Percent abundance = black; density (organisms/m2) = blue. SPCURE - PREDOMINANT AND IMPORTANT MACOINVERTEBRATE SPECIES AND THEIR OCCURRENCE SOUTH PLATTE RIVER Fall 2008 - Rock Baskets * Taxa S84 S76 S30 S21/22 N18 N45/46 TURBELLARIA Dugesia sp. 0.0 0.6 49.6 54.2 23.4 14.2 0 75 1109 1587 282 411
AMPHIPODA Crangonyx sp. 52.7 4.8 6.6 1.2 5.1 4.4 1264 615 148 35 61 129
Hyalella azteca 26.3 0.0 0.8 0.0 0.0 1.1 6300170 032
EPHEMEROPTERA Tricorythodes explicatus 7.4 31.1 3.1 3.0 1.4 0.2 177 3983 69 88 17 7
TRICHOPTERA Cheumatopsyche sp. 3.8 9.1 7.9 1.9 2.5 11.1 91 1170 177 56 30 323
Hydropsyche sp. 0.0 0.8 4.1 5.1 4.5 37.8 0 105 92 150 55 1097
DIPTERA CHIRONOMIDAE Chironomus sp. 0.4 2.9 1.9 0.2 4.3 2.5 10 375 42 5 52 72
Cricotopus sp. 1.2 1.2 2.7 5.1 12.7 2.1 28 150 60 149 152 62
Microtendipes sp. 2.8 40.4 4.8 2.8 3.7 0.1 67 5168 108 82 44 3
Phaenopsectra sp. 0.5 0.4 6.3 3.6 22.4 3.2 11 45 141 105 269 94
Rheocricotopus sp. 0.0 0.0 0.4 2.4 2.3 3.6 0 0 8 72 28 103
* Percent abundance = black; density (organisms/m2) = blue. SOUTH PLATTE RIVER
MACROINVERTEBRATE DATA SUMMARY - METRICS COMPARISONS FALL 2007-2008
FALL 2007 metric S84 S76 S62 S51 S34 S30 S21/22 S7 N4 N18 N28 N34 N45/46 diversity 2.75 2.75 3.04 3.27 2.76 3.82 2.68 3.09 2.86 3.28 2.90 2.73 3.10 HBI 4.79 4.61 4.70 4.63 4.66 5.82 6.22 6.82 4.75 5.58 5.25 5.22 5.69 ICI 32 36 30 26 30 32 26 24 26 28 32 30 24 ICI/HBI ratio 6.68 7.81 6.38 5.62 6.44 5.50 4.18 3.52 5.47 5.02 6.10 5.75 4.22 EPT taxa 8998886667877 total taxa 31 30 25 22 24 37 30 25 29 31 36 30 27 density 10909 14985 8484 8423 4640 7583 4325 5783 3045 5640 3729 3903 1476
FALL 2008 metric S84 S76 S62 S51 S34 S30 S21/22 S7 N4 N18 N28 N34 N45/46 diversity 2.31 2.71 2.55 2.64 3.01 3.54 3.35 3.21 3.49 3.28 3.25 3.82 3.29 HBI 5.45 4.61 4.49 4.58 4.75 5.12 5.74 6.63 5.93 5.42 5.89 5.97 5.96 ICI 26 26 30 24 30 28 24 22 24 30 26 24 24 ICI/HBI ratio 4.77 5.64 6.68 5.24 6.32 5.47 4.18 3.32 4.05 5.54 4.41 4.02 4.03 EPT taxa 6667786866777 total taxa 35 28 25 27 31 35 26 31 25 35 33 30 30 density 4832 5919 9917 7861 4034 5240 7141 5325 1451 9006 1460 3079 3711 SOUTH PLATTE RIVER
MACROINVERTEBRATE DATA SUMMARY - METRICS COMPARISONS SPRING 2008
SPRING 2008 metric S84 S76 S30 S21/22 N18 N45/46 diversity 2.89 2.30 2.34 1.86 2.58 2.71 HBI 7.54 7.43 7.24 8.33 7.33 7.93 ICI 18 24 18 14 18 14 ICI/HBI ratio 2.39 3.23 2.49 1.68 2.46 1.77 EPT taxa 464454 total taxa 31 33 25 24 29 25 density 1791 2750 6180 3923 4403 3281 SOUTH PLATTE RIVER
MACROINVERTEBRATE DATA SUMMARY - METRICS COMPARISONS FALL 2008 - Rock Baskets
FALL 2008 metric S84 S76 S30 S21/22 N18 N45/46 diversity 2.08 2.48 3.05 2.88 3.68 3.25 HBI 6.44 5.42 5.05 4.91 5.87 5.56 ICI 10 22 24 28 26 28 ICI/HBI ratio 1.55 4.06 4.75 5.70 4.43 5.04 EPT taxa 237896 total taxa 20 29 38 38 38 38 density 2399 12804 2237 2929 1202 2904 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY FALL 2007
COMMUNITY PARAMETERS
S84 S76 S62 S51 S34 S30 S21/22 Total Density (N/m2) 10909 14985 8484 8423 4640 7583 4325 Diversity (d) 2.75 2.75 3.04 3.27 2.76 3.82 2.68 Total Number of Taxa 31 30 25 22 24 37 30 % Dominant Taxon 45.17 31.48 36.60 23.33 47.11 23.34 42.83 No. EPT Taxa 8998886 HBI 4.79 4.61 4.70 4.63 4.66 5.82 6.22 % Diptera 16.57 8.11 12.73 10.06 4.77 24.83 8.32 % Oligochaeta 1.17 3.05 1.94 1.16 6.63 18.40 31.82 % Sprawlers 46.61 25.48 12.82 27.78 7.84 12.17 3.21 % Chironomidae 14.99 4.60 9.55 7.21 3.88 22.65 7.54 % Chironomus + Cricotopus (of 33.03 45.65 70.37 27.16 62.50 42.36 44.83 Chironomidae) No. Mayfly Taxa 3454444 No. Caddisfly Taxa 5544442 No. Diptera Taxa 11 12 9 8 10 19 15 % Mayflies 47.03 32.53 25.37 45.59 30.63 21.66 8.58 % Caddisflies 24.20 54.90 52.60 28.23 51.24 29.87 43.35 % Tribe Tanytarsini 0.00 0.00 0.00 0.00 0.00 0.69 0.17 % Tolerant Organisms 2.21 4.00 3.18 5.43 8.32 21.86 35.11 % Non-Insects 11.72 4.40 9.28 16.12 13.37 23.64 39.74 % Non-insects + % Diptera 28.29 12.51 22.01 26.18 18.13 47.78 47.89 (excluding Tanytarsini) EPT (abundance) 7770.00 13102.50 6615.00 6217.50 3798.75 3907.50 2246.25 Chironomidae (abundance) 1635.00 690.00 810.00 607.50 180.00 1717.50 326.25 EPT/Chironomid ratio 4.75 18.99 8.17 10.23 21.10 2.28 6.89 ICI/HBI ratio 6.68 7.81 6.38 5.62 6.44 5.50 4.18 ICI 32 36 30 26 30 32 26
S7 N4 N18 N28 N34 N45/46 Total Density (N/m2) 5783 3045 5640 3729 3903 1476 Diversity (d) 3.09 2.86 3.28 2.90 2.73 3.10 Total Number of Taxa 25 29 31 36 30 27 % Dominant Taxon 30.09 30.20 23.40 41.44 45.42 34.18 No. EPT Taxa 667877 HBI 6.82 4.75 5.58 5.25 5.22 5.69 % Diptera 14.92 11.13 27.53 18.61 14.03 21.78 % Oligochaeta 39.95 5.81 13.56 11.67 11.60 17.45 % Sprawlers 2.08 1.97 1.86 3.22 1.54 3.69 % Chironomidae 14.27 10.79 25.80 17.10 13.52 20.80 % Chironomus + Cricotopus (of 60.91 72.60 81.96 81.18 82.94 65.80 Chironomidae) No. Mayfly Taxa 444544 No. Caddisfly Taxa 223333 No. Diptera Taxa 13 16 14 16 14 8 % Mayflies 14.79 34.73 27.93 22.93 21.40 21.27 % Caddisflies 22.05 20.99 24.60 42.34 48.05 34.86 % Tribe Tanytarsini 0.00 0.05 0.27 0.30 0.06 0.00 % Tolerant Organisms 41.63 7.98 14.63 14.18 13.65 19.21 % Non-Insects 48.25 33.15 19.81 15.92 16.53 22.09 % Non-insects + % Diptera 63.16 44.24 47.07 34.22 30.49 43.87 (excluding Tanytarsini) EPT (abundance) 2130.00 1696.50 2962.50 2433.75 2710.00 828.50 Chironomidae (abundance) 825.00 328.50 1455.00 637.50 527.50 307.00 EPT/Chironomid ratio 2.58 5.16 2.04 3.82 5.14 2.70 ICI/HBI ratio 3.52 5.47 5.02 6.10 5.75 4.22 ICI 24 26 28 32 30 24 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY FALL 2007
RELATIVE ABUNDANCE
Relative Abundance by Order S84 S76 S62 S51 S34 S30 S21/22 TURBELLARIA 7.36 0.50 5.57 11.93 5.01 3.86 7.20 NEMERTEA 0.00 0.00 0.18 0.09 0.00 0.00 0.09 OLIGOCHAETA 1.17 3.05 1.94 1.16 6.63 18.40 31.82 HIRUDINEA 0.01 0.00 0.00 0.00 0.00 0.00 0.00 ISOPODA 0.14 0.00 0.00 0.00 0.00 0.00 0.43 AMPHIPODA 1.86 0.00 0.00 0.00 0.16 0.40 0.09 DECAPODA 0.01 0.00 0.00 0.00 0.00 0.01 0.00 ACARI 0.21 0.50 0.71 2.32 1.37 0.89 0.00 EPHEMEROPTERA 47.03 32.53 25.37 45.59 30.63 21.66 8.58 HEMIPTERA 0.00 0.00 0.00 0.00 0.00 0.00 0.00 TRICHOPTERA 24.20 54.90 52.60 28.23 51.24 29.87 43.35 LEPIDOPTERA 0.48 0.05 0.01 0.00 0.00 0.00 0.00 DIPTERA 16.57 8.11 12.73 10.06 4.77 24.83 8.32 GASTROPODA 0.34 0.30 0.00 0.00 0.00 0.00 0.00 BIVALVIA 0.64 0.05 0.88 0.62 0.19 0.10 0.12 Totals: 100.00 100.00 100.00 100.00 100.00 100.00 100.00
Relative Abundance by Order S7 N4 N18 N28 N34 N45/46 TURBELLARIA 7.52 24.83 5.05 1.81 2.56 2.00 NEMERTEA 0.00 0.00 0.00 0.00 0.38 0.17 OLIGOCHAETA 39.95 5.81 13.56 11.67 11.60 17.45 HIRUDINEA 0.00 0.00 0.00 0.00 0.00 0.07 ISOPODA 0.00 0.49 0.00 0.40 0.77 0.34 AMPHIPODA 0.00 0.00 0.00 0.80 0.19 0.00 DECAPODA 0.00 0.00 0.00 0.01 0.00 0.00 ACARI 0.26 0.64 0.80 1.21 0.64 1.19 EPHEMEROPTERA 14.79 34.73 27.93 22.93 21.40 21.27 HEMIPTERA 0.00 0.00 0.13 0.20 0.00 0.00 TRICHOPTERA 22.05 20.99 24.60 42.34 48.05 34.86 LEPIDOPTERA 0.00 0.00 0.00 0.00 0.00 0.00 DIPTERA 14.92 11.13 27.53 18.61 14.03 21.78 GASTROPODA 0.00 0.00 0.13 0.00 0.13 0.10 BIVALVIA 0.52 1.38 0.27 0.01 0.26 0.78 Totals: 100.00 100.00 100.00 100.00 100.00 100.00 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY FALL 2007
DENSITY
Density by Order S84 S76 S62 S51 S34 S30 S21/22 TURBELLARIA 803 75 473 1005 233 293 311 NEMERTEA 0 0 15 8004 OLIGOCHAETA 128 458 165 98 308 1395 1376 HIRUDINEA 1000000 ISOPODA 15 0000019 AMPHIPODA 203 0008304 DECAPODA 1000010 ACARI 23 75 60 195 64 68 0 EPHEMEROPTERA 5130 4875 2153 3840 1421 1643 371 HEMIPTERA 0000000 TRICHOPTERA 2640 8228 4463 2378 2378 2265 1875 LEPIDOPTERA 53 810000 DIPTERA 1808 1215 1080 848 221 1883 360 GASTROPODA 38 45 00000 BIVALVIA 70 8 75 53 9 8 5 Totals: 10909 14985 8484 8423 4640 7583 4325
Density by Order S7 N4 N18 N28 N34 N45/46 TURBELLARIA 435 756 285 68 100 30 NEMERTEA 0000153 OLIGOCHAETA 2310 177 765 435 453 258 HIRUDINEA 000001 ISOPODA 0 15 0 15 30 5 AMPHIPODA 0 0 0 30 8 0 DECAPODA 000100 ACARI 15 20 45 45 25 18 EPHEMEROPTERA 855 1058 1575 855 835 314 HEMIPTERA 008800 TRICHOPTERA 1275 639 1388 1579 1875 515 LEPIDOPTERA 000000 DIPTERA 863 339 1553 694 548 322 GASTROPODA 008052 BIVALVIA 30 42 15 1 10 12 Totals: 5783 3045 5640 3729 3903 1476 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY FALL 2008
COMMUNITY PARAMETERS
S84 S76 S62 S51 S34 S30 S21/22 Total Density (N/m2) 4832 5919 9917 7861 4034 5240 7141 Diversity (d) 2.31 2.71 2.55 2.64 3.01 3.54 3.35 Total Number of Taxa 35 28 25 27 31 35 26 % Dominant Taxon 61.48 51.32 55.36 54.00 29.07 29.49 24.89 No. EPT Taxa 6667786 HBI 5.45 4.61 4.49 4.58 4.75 5.12 5.74 % Diptera 22.25 20.78 13.76 11.07 16.12 23.26 20.59 % Oligochaeta 1.29 0.51 0.08 0.76 0.93 1.07 13.60 % Sprawlers 9.99 52.97 56.80 55.81 19.90 11.95 5.15 % Chironomidae 19.61 19.77 10.82 10.40 14.44 21.18 19.22 % Chironomus + Cricotopus (of 68.33 22.44 25.17 31.19 63.95 42.91 51.64 Chironomidae) No. Mayfly Taxa 4334454 No. Caddisfly Taxa 2333332 No. Diptera Taxa 15 15 14 15 18 17 11 % Mayflies 6.13 55.37 66.10 64.88 45.74 49.24 23.48 % Caddisflies 61.63 13.94 9.00 8.59 7.56 16.10 16.70 % Tribe Tanytarsini 0.00 0.00 0.08 0.00 0.06 0.07 0.00 % Tolerant Organisms 4.45 2.79 2.04 5.25 2.17 5.74 20.90 % Non-Insects 9.94 9.90 11.06 15.47 30.58 11.40 39.24 % Non-insects + % Diptera 32.19 30.68 24.75 26.54 46.63 34.59 59.82 (excluding Tanytarsini) EPT (abundance) 3274.43 4102.50 7447.50 5775.00 2150.00 3423.75 2868.75 Chironomidae (abundance) 947.58 1170.00 1072.50 817.50 582.50 1110.00 1372.50 EPT/Chironomid ratio 3.46 3.51 6.94 7.06 3.69 3.08 2.09 ICI/HBI ratio 4.77 5.64 6.68 5.24 6.32 5.47 4.18 ICI 26 26 30 24 30 28 24
S7 N4 N18 N28 N34 N45/46 Total Density (N/m2) 5325 1451 9006 1460 3079 3711 Diversity (d) 3.21 3.49 3.28 3.25 3.82 3.29 Total Number of Taxa 31 25 35 33 30 30 % Dominant Taxon 30.56 16.28 26.40 34.41 13.34 23.04 No. EPT Taxa 866777 HBI 6.63 5.93 5.42 5.89 5.97 5.96 % Diptera 13.52 28.68 43.57 33.47 48.05 10.02 % Oligochaeta 33.94 16.06 1.42 13.82 9.20 25.57 % Sprawlers 11.55 22.09 7.50 8.56 8.22 4.75 % Chironomidae 10.56 27.13 27.32 30.99 44.76 10.01 % Chironomus + Cricotopus (of 61.33 51.59 55.18 66.99 50.07 64.65 Chironomidae) No. Mayfly Taxa 544444 No. Caddisfly Taxa 322333 No. Diptera Taxa 13 13 19 15 16 12 % Mayflies 25.21 37.90 45.64 48.11 24.00 22.74 % Caddisflies 1.13 1.16 7.41 2.65 15.35 17.28 % Tribe Tanytarsini 0.00 0.17 0.17 0.30 0.00 0.00 % Tolerant Organisms 37.75 19.85 2.67 16.09 11.51 27.29 % Non-Insects 60.14 32.26 3.38 15.59 12.61 49.96 % Non-insects + % Diptera 73.66 60.77 46.78 48.76 60.66 59.98 (excluding Tanytarsini) EPT (abundance) 1402.50 566.88 4777.50 741.25 1211.25 1485.00 Chironomidae (abundance) 562.50 393.75 2460.00 452.50 1378.13 371.25 EPT/Chironomid ratio 2.49 1.44 1.94 1.64 0.88 4.00 ICI/HBI ratio 3.32 4.05 5.54 4.41 4.02 4.03 ICI 22 24 30 26 24 24 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY FALL 2008
RELATIVE ABUNDANCE
Relative Abundance by Order S84 S76 S62 S51 S34 S30 S21/22 TURBELLARIA 1.05 8.49 9.08 11.07 29.07 7.01 24.89 NEMERTEA 0.47 0.13 0.00 0.00 0.00 0.00 0.00 NEMATODA 0.00 0.00 0.00 0.00 0.00 0.00 0.00 OLIGOCHAETA 1.29 0.51 0.08 0.76 0.93 1.07 13.60 HIRUDINEA 0.10 0.00 0.00 0.00 0.00 0.00 0.00 ISOPODA 1.26 0.00 0.00 0.00 0.00 0.00 0.42 AMPHIPODA 5.28 0.00 0.00 0.00 0.00 0.14 0.11 DECAPODA 0.02 0.00 0.00 0.00 0.01 0.01 0.00 ACARI 0.47 0.76 1.82 1.72 0.56 1.79 0.11 EPHEMEROPTERA 6.13 55.37 66.10 64.88 45.74 49.24 23.48 ODONATA 0.00 0.00 0.00 0.00 0.00 0.00 0.00 HEMIPTERA 0.05 0.00 0.00 0.00 0.00 0.00 0.00 TRICHOPTERA 61.63 13.94 9.00 8.59 7.56 16.10 16.70 LEPIDOPTERA 0.00 0.01 0.08 0.00 0.00 0.00 0.00 DIPTERA 22.25 20.78 13.76 11.07 16.12 23.26 20.59 GASTROPODA 0.00 0.00 0.00 0.00 0.00 0.01 0.00 BIVALVIA 0.00 0.02 0.09 1.92 0.01 1.36 0.11 Totals: 100.00 100.00 100.00 100.00 100.00 100.00 100.00
Relative Abundance by Order S7 N4 N18 N28 N34 N45/46 TURBELLARIA 21.97 14.69 1.33 0.17 2.44 23.04 NEMERTEA 0.00 0.00 0.00 0.00 0.00 0.00 NEMATODA 0.14 0.00 0.17 0.00 0.00 0.20 OLIGOCHAETA 33.94 16.06 1.42 13.82 9.20 25.57 HIRUDINEA 0.00 0.00 0.00 0.00 0.00 0.00 ISOPODA 0.14 0.30 0.00 0.00 0.97 0.81 AMPHIPODA 0.00 0.17 0.08 1.37 0.00 0.20 DECAPODA 0.00 0.00 0.00 0.00 0.00 0.00 ACARI 0.14 0.00 0.33 0.13 0.00 0.00 EPHEMEROPTERA 25.21 37.90 45.64 48.11 24.00 22.74 ODONATA 0.00 0.00 0.00 0.00 0.00 0.00 HEMIPTERA 0.00 0.00 0.00 0.17 0.00 0.00 TRICHOPTERA 1.13 1.16 7.41 2.65 15.35 17.28 LEPIDOPTERA 0.00 0.00 0.00 0.00 0.00 0.00 DIPTERA 13.52 28.68 43.57 33.47 48.05 10.02 GASTROPODA 0.00 0.00 0.00 0.00 0.00 0.00 BIVALVIA 3.80 1.03 0.05 0.10 0.00 0.13 Totals: 100.00 100.00 100.00 100.00 100.00 100.00 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY FALL 2008
DENSITY
Density by Order S84 S76 S62 S51 S34 S30 S21/22 TURBELLARIA 51 503 900 870 1173 368 1778 NEMERTEA 23 800000 NEMATODA 0000000 OLIGOCHAETA 63 30 8 60 38 56 971 HIRUDINEA 5000000 ISOPODA 61 0000030 AMPHIPODA 255 000088 DECAPODA 1000110 ACARI 23 45 180 135 23 94 8 EPHEMEROPTERA 296 3278 6555 5100 1845 2580 1676 ODONATA 0000000 HEMIPTERA 3000000 TRICHOPTERA 2978 825 893 675 305 844 1193 LEPIDOPTERA 0180000 DIPTERA 1075 1230 1365 870 650 1219 1470 GASTROPODA 0000010 BIVALVIA 0 1 9 151 1 71 8 Totals: 4832 5919 9917 7861 4034 5240 7141
Density by Order S7 N4 N18 N28 N34 N45/46 TURBELLARIA 1170 213 120 3 75 855 NEMERTEA 000000 NEMATODA 8 0 15 0 0 8 OLIGOCHAETA 1808 233 128 202 283 949 HIRUDINEA 000000 ISOPODA 84003030 AMPHIPODA 0 3 8 20 0 8 DECAPODA 000000 ACARI 8 0 30 2 0 0 EPHEMEROPTERA 1343 550 4110 703 739 844 ODONATA 000000 HEMIPTERA 000300 TRICHOPTERA 60 17 668 39 473 641 LEPIDOPTERA 000000 DIPTERA 720 416 3924 489 1479 372 GASTROPODA 000000 BIVALVIA 203 15 5205 Totals: 5325 1451 9006 1460 3079 3711 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY SPRING 2008
COMMUNITY PARAMETERS
S84 S76 S30 S21/22 N18 N45/46 Total Density (N/m2) 1791 2750 6180 3923 4403 3281 Diversity (d) 2.89 2.30 2.34 1.86 2.58 2.71 Total Number of Taxa 31 33 25 24 29 25 % Dominant Taxon 40.93 57.28 47.33 68.01 34.75 29.56 No. EPT Taxa 464454 HBI 7.54 7.43 7.24 8.33 7.33 7.93 % Diptera 49.93 17.46 21.12 19.25 45.23 37.41 % Oligochaeta 41.45 59.07 50.24 75.40 36.20 51.43 % Sprawlers 24.71 21.68 3.52 2.61 2.13 2.36 % Chironomidae 49.41 15.27 20.51 19.06 44.38 36.04 % Chironomus + Cricotopus (of 14.41 80.36 87.57 83.61 95.39 95.77 Chironomidae) No. Mayfly Taxa 222322 No. Caddisfly Taxa 242132 No. Diptera Taxa 19 16 14 12 17 12 % Mayflies 1.05 18.96 25.36 2.87 13.80 4.88 % Caddisflies 0.42 3.68 2.55 1.02 4.26 5.33 % Tribe Tanytarsini 7.33 0.00 0.00 0.00 0.00 0.00 % Tolerant Organisms 49.96 58.80 48.67 75.02 36.63 51.75 % Non-Insects 48.60 59.91 50.97 76.86 36.63 52.38 % Non-insects + % Diptera 91.21 77.36 72.09 96.11 81.86 89.79 (excluding Tanytarsini) EPT (abundance) 26.25 622.50 1725.00 152.50 795.00 335.00 Chironomidae (abundance) 885.00 420.00 1267.50 747.50 1953.75 1182.50 EPT/Chironomid ratio 0.03 1.48 1.36 0.20 0.41 0.28 ICI/HBI ratio 2.39 3.23 2.49 1.68 2.46 1.77 ICI 18 24 18 14 18 14 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY SPRING 2008
RELATIVE ABUNDANCE
Relative Abundance by Order S84 S76 S30 S21/22 N18 N45/46 TURBELLARIA 0.63 0.14 0.36 1.08 0.09 0.38 NEMERTEA 0.00 0.00 0.00 0.00 0.00 0.23 OLIGOCHAETA 41.45 59.07 50.24 75.40 36.20 51.43 ISOPODA 0.13 0.00 0.00 0.00 0.17 0.02 AMPHIPODA 5.86 0.27 0.00 0.00 0.00 0.00 DECAPODA 0.00 0.02 0.00 0.00 0.00 0.00 ACARI 0.31 0.27 0.24 0.00 0.00 0.08 EPHEMEROPTERA 1.05 18.96 25.36 2.87 13.80 4.88 ODONATA 0.00 0.00 0.00 0.00 0.09 0.00 TRICHOPTERA 0.42 3.68 2.55 1.02 4.26 5.33 DIPTERA 49.93 17.46 21.12 19.25 45.23 37.41 BIVALVIA 0.21 0.14 0.12 0.38 0.17 0.24 Totals: 100.00 100.00 100.00 100.00 100.00 100.00 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY SPRING 2008
DENSITY
Density by Order S84 S76 S30 S21/22 N18 N45/46 TURBELLARIA 11 4 23 43 4 13 NEMERTEA 000008 OLIGOCHAETA 743 1624 3105 2958 1594 1688 ISOPODA 200081 AMPHIPODA 105 80000 DECAPODA 010000 ACARI 6 8 15 0 0 3 EPHEMEROPTERA 19 521 1568 113 608 160 ODONATA 000040 TRICHOPTERA 8 101 158 40 188 175 DIPTERA 894 480 1305 755 1991 1228 BIVALVIA 4 4 8 15 8 8 Totals: 1791 2750 6180 3923 4403 3281 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY FALL 2008 - Rock Baskets
COMMUNITY PARAMETERS
S84 S76 S30 S21/22 N18 N45/46 Total Density (N/m2) 2399 12804 2237 2929 1202 2904 Diversity (d) 2.08 2.48 3.05 2.88 3.68 3.25 Total Number of Taxa 20 29 38 38 38 38 % Dominant Taxon 52.68 40.36 49.58 54.18 23.43 37.78 No. EPT Taxa 237896 HBI 6.44 5.42 5.05 4.91 5.87 5.56 % Diptera 5.42 51.96 21.73 22.89 56.51 15.07 % Oligochaeta 0.08 0.82 1.92 3.07 0.17 13.65 % Sprawlers 7.68 31.98 6.97 8.68 9.86 6.38 % Chironomidae 5.42 51.96 20.65 19.89 54.06 14.63 % Chironomus + Cricotopus (of 28.46 7.89 22.08 26.44 31.33 31.45 Chironomidae) No. Mayfly Taxa 114463 No. Caddisfly Taxa 123433 No. Diptera Taxa 9 13 20 20 22 18 % Mayflies 7.39 31.10 4.29 10.55 5.95 0.49 % Caddisflies 3.80 9.96 12.29 7.24 7.41 49.25 % Tribe Tanytarsini 0.10 0.35 1.07 0.58 0.92 0.23 % Tolerant Organisms 29.77 5.05 7.20 7.20 8.70 19.49 % Non-Insects 82.79 6.86 61.60 59.28 30.13 35.15 % Non-insects + % Diptera 88.11 58.47 82.25 81.59 85.73 49.99 (excluding Tanytarsini) EPT (abundance) 268.50 5257.50 371.00 521.13 160.50 1444.76 Chironomidae (abundance) 130.00 6652.50 462.00 582.56 649.50 424.95 EPT/Chironomid ratio 2.07 0.79 0.80 0.89 0.25 3.40 ICI/HBI ratio 1.55 4.06 4.75 5.70 4.43 5.04 ICI 10 22 24 28 26 28 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY FALL 2008 - Rock Baskets
RELATIVE ABUNDANCE
Relative Abundance by Order S84 S76 S30 S21/22 N18 N45/46 TURBELLARIA 0.00 0.59 49.58 54.18 23.43 14.15 OLIGOCHAETA 0.08 0.82 1.92 3.07 0.17 13.65 ISOPODA 2.01 0.06 0.89 0.38 0.71 1.22 AMPHIPODA 78.95 4.80 7.38 1.20 5.08 5.51 DECAPODA 1.13 0.30 1.83 0.38 0.25 0.31 EPHEMEROPTERA 7.39 31.10 4.29 10.55 5.95 0.49 ODONATA 0.55 0.12 0.09 0.03 0.00 0.03 HEMIPTERA 0.04 0.00 0.00 0.00 0.00 0.00 TRICHOPTERA 3.80 9.96 12.29 7.24 7.41 49.25 DIPTERA 5.42 51.96 21.73 22.89 56.51 15.07 GASTROPODA 0.63 0.27 0.00 0.00 0.00 0.00 BIVALVIA 0.00 0.03 0.00 0.07 0.50 0.31 Totals: 100.00 100.00 100.00 100.00 100.00 100.00 SOUTH PLATTE RIVER MACROINVERTEBRATE DATA SUMMARY FALL 2008 - Rock Baskets
DENSITY
Density by Order S84 S76 S30 S21/22 N18 N45/46 TURBELLARIA 0 75 1109 1587 282 411 OLIGOCHAETA 2 105 43 90 2 396 ISOPODA 48 8 20 11 9 35 AMPHIPODA 1894 615 165 35 61 160 DECAPODA 27 38 41 11 3 9 EPHEMEROPTERA 177 3983 96 309 72 14 ODONATA 13 15 2101 HEMIPTERA 100000 TRICHOPTERA 91 1275 275 212 89 1430 DIPTERA 130 6653 486 670 679 438 GASTROPODA 15 34 0000 BIVALVIA 040269 Totals: 2399 12804 2237 2929 1202 2904