Status and Trend Monitoring Summary for Selected Pope and Douglas County, Minnesota Lakes 2000 (Lakes: Ann, Gilchrist, Grove, Leven, Reno, Villard, Smith)
Minnesota Pollution Control Agency Environmental Outcomes Division Environmental Monitoring and Analysis Section Andrea Plevan and Steve Heiskary
September 2001
Printed on recycled paper containing at least 10 percent fibers from paper recycled by consumers. This material may be made available in other formats, including Braille, large format and audiotape. MPCA Status and Trend Monitoring Summary for 2000 Pope County Lakes
Part 1: Purpose of study and background information on MN lakes
The Minnesota Pollution Control Agency’s (MPCA) core lake-monitoring programs include the Citizen Lake Monitoring Program (CLMP), the Lake Assessment Program (LAP), and the Clean Water Partnership (CWP) Program. In addition to these programs, the MPCA annually monitors numerous lakes to provide baseline water quality data, provide data for potential LAP and CWP lakes, characterize lake conditions in different regions of the state, examine year-to-year variability in ecoregion reference lakes, and provide additional trophic status data for lakes exhibiting trends in Secchi transparency. In the latter case, we attempt to determine if the trends in Secchi transparency are “real,” i.e., if supporting trophic status data substantiate whether a change in trophic status has occurred. The lake sampling efforts also provide a means to respond to citizen concerns about protecting or improving the lake in cases where no data exists to evaluate the quality of the lake. For efficient sampling, we tend to select geographic clusters of lakes (e.g., focus on a specific county) whenever possible.
In 2000, the MPCA monitored the following six lakes: Ann, Gilchrist, Grove, Leven, Reno, and Villard Lakes in Pope County; and Smith Lake in adjacent Douglas County. Water quality samples were collected monthly from June through September at most lakes. These lakes represent a cross section of the lakes found in this area in terms of water quality, lake morphometry and watershed characteristics. They also represent a range in terms of the amount of data available; ranging from a completed LAP study on Gilchrist Lake, completed Clean Water Partnership Phases I and II work on Grove, to Ann Lake which only had Secchi data. Grove and Smith Lakes were a part of MPCA’s ecoregion reference lake monitoring effort in the mid 1980s. More recently, several of the lakes have been monitored as part of a Pope County water plan and efforts of a coalition of lake associations. MPCA monitoring in 2000 was conducted by Mike Vavricka, Steve Heiskary, and student interns Stephanie Johnson and Dan Barringer.
The state of Minnesota is divided into seven ecoregions (Figure 1), based on soils, landform, potential natural vegetation, and land use. All of the lakes monitored for this study are located in the North Central Hardwood Forest (NCHF) ecoregion. By comparing a lake’s water quality to that of reference lakes in the same ecoregion, one can gain a clearer picture of where the lake falls in the spectrum of water quality parameters relative to other lakes in that ecoregion.
Lake phosphorus criteria have been established for Minnesota lakes located in several of the ecoregions represented in Minnesota (Table 1; Heiskary and Wilson 1988). These criteria vary depending on the intended use of the water resource. For example, phosphorus criteria for a drinking water supply are more stringent than the criteria for recreation and aesthetics. Phosphorus concentrations in the lakes in the present study can be compared to the lake phosphorus criteria in Table 1. In general, lakes that are at or below the specific criterion for primary contact recreation and aesthetics will have adequate transparency and sufficiently low amounts of algae to support swimmable use throughout most of the summer. Whenever possible these lakes should be protected from increases in nutrient concentrations that would tend to stimulate algal and plant growth and
1 reduce transparency. For lakes above the phosphorus criteria, the suggested levels may serve as a restoration goal for the lake; however, restoration goals should be determined by individual examination of the lake and its watershed characteristics. Thus criteria, which were originally developed in 1988, may be modified in the future, as Minnesota is in the process of formally developing (through rule-making) nutrient criteria as a part of a national effort.
Lake depth can have a significant influence on lake processes and water quality. One such process is thermal stratification (formation of distinct temperature layers), in which deep lakes (maximum depths of 30 - 40 feet or more) often stratify (form layers) during the summer months and are referred to as dimictic. Shallow lakes (maximum depths of 20 feet or less) in contrast, typically do not stratify and are often referred to as polymictic. Some lakes, intermediate between these two (e.g., lakes with moderate depth and large surface area) may stratify intermittently during calm periods. The combined effect of depth and stratification can influence overall water quality. The epilimnia of deeper, stratified lakes often have lower phosphorus concentrations as compared to shallow well-mixed lakes in the same ecoregion (Table 2). The percentiles in Table 2 can provide an additional basis for comparing observed summer mean TP and may further serve as a guide for deriving an appropriate TP goal for the lake. Note that the percentile values (median, for example) can be quite different within an ecoregion for different types of lakes.
Stream water quality was not monitored as a part of this study. However, we have provided typical concentrations of total phosphorus and total suspended solids for streams in six of MN’s ecoregions (Table 3). If data are available from other sources, local stream water quality parameters can be compared to these values. The values in Table 3 represent the “central tendency” (25th to 75th percentiles) of concentrations from representative, minimally-impacted river sites in each ecoregion. These data were derived from Minnesota’s Milestone monitoring program and should not be considered as “reference” streams nor does this represent the most pristine streams in each ecoregion. The data do, however provide useful yardsticks for evaluating data obtained from streams in the respective ecoregions.
2 Figure 1. Minnesota’s seven ecoregions as mapped by U.S. EPA.
Northern Minnesota Wetlands
Red River Valley Northern Lakes and Forests Pope County North Central Hardwood Forests
Northern Glaciated Plains Driftless Area
Western CornBelt Plains
Table 1. Minnesota lake total phosphorus criteria, by ecoregion. (Heiskary and Wilson 1988) Ecoregion Most Sensitive Use TP Criteria Northern Lakes and Forests drinking water supply < 15 µg/L cold water fishery < 15 µg/L primary contact recreation and aesthetics < 30 µg/L North Central Hardwood drinking water supply < 30 µg/L Forests primary contact recreation and aesthetics < 40 µg/L Western Corn Belt Plains drinking water supply < 40 µg/L primary contact recreation (full support) < 40 µg/L (partial support) < 90 µg/L Northern Glaciated Plains primary contact recreation and aesthetics < 90 µg/L (partial support)
3 Table 2. Total phosphorus concentrations(µg/L), by mixing status and ecoregion. Based on all assessed lakes for each ecoregion. D = Dimictic, I = Intermittent, P = Polymictic.
Northern Lakes and North Central Western Corn Belt Forests Hardwood Forest Plains
Percentile D I P D I P D I P 90 % 37 53 57 104 263 344 -- -- 284 75 % 29 35 39 58 100 161 101 195 211 50 % (median) 20 26 29 39 62 89 69 135 141 25 % 13 19 19 25 38 50 39 58 97 10 % 9 131219213225--69
# of obs. 257 87 199 152 71 145 4 3 38
Table 3. Interquartile range of annual mean concentrations for minimally impacted streams in Minnesota, by ecoregion. Data from 1970-1992. TP = total phosphorus, TSS = total suspended solids. (McCollor and Heiskary 1993)
TP (mg/l) TSS (mg/l) Region 25% 50% 75% 25% 50% 75% NLF 0.02 0.04 0.05 1.8 3.3 6.0 NMW 0.04 0.06 0.09 4.8 8.6 16 NCHF 0.06 0.09 0.15 4.8 8.8 16 NGP 0.09 0.16 0.25 11 34 63 RRV 0.11 0.19 0.30 11 28 59 WCBP 0.16 0.24 0.33 10 27 61
4 Part 2: Lake survey
Methods
This report includes data from 2000 as well as previously collected data available in STORET, U.S. EPA’s national water quality data bank (Appendix). The following discussion assumes familiarity with basic limnologic terms as used in a “Citizens Guide to Lake Protection” and as commonly used in LAP reports. A glossary is included in the Appendix as well.
For the lake survey, one to two sites in each lake were monitored monthly, from June through September. If more than one site was monitored, one of the sites was the “primary site,” and the other site a “secondary site.” If only one site in a lake was monitored, it was treated as a primary site. Lake size and morphometry determined the number of sites monitored per lake. At each primary site, the following parameters were analyzed from a surface sample of water: chlorophyll a, total phosphorus (TP), total Kjeldahl nitrogen (TKN), total suspended solids (TSS), total suspended volatiles (TSV), alkalinity, color, pH, and conductivity. Additionally, a temperature and dissolved oxygen depth profile was taken. At sites that were stratified, total phosphorus was analyzed from a hypolimnetic (bottom) water sample as well. At each secondary site, only surface chlorophyll a and total phosphorus were analyzed. Secchi disk transparency was recorded at all sites.
Additional information, such as bathymetric and location maps, was obtained from the DNR’s lakefinder website (http://www.dnr.state.mn.us/lakefind/index.html) and the MPCA website (http://www.pca.state.mn.us). Watershed areas were estimated from USGS quad maps for the majority of the lakes, except for Gilchrist and Grove Lakes, for which the watershed areas had already been delineated.
Lake summer-mean water quality parameters for 2000 are presented in Table 4. The typical range (25th to 75th percentile) for reference lakes in the NCHF ecoregion are provided for comparison purposes. Carlson’s Trophic State Index (TSI) values based on TP, chlorophyll a and Secchi were calculated for each lake as well (Table 5). Additionally, percentile rankings were estimated (Table 5) based on assessed lakes from the NCHF ecoregion. The ranking represents the percentage of lakes that rank lower in TSI than the ranked lake; therefore, a higher ranking corresponds to relatively better water quality, and vice versa. More details on these rankings can be obtained from the MPCA’s “Minnesota lake water quality assessment data: 2000” report. Figure 2 outlines the trophic state estimates, ranging from oligotrophic to hypereutrophic, that correspond to the multiple TSIs.
In the following discussion, trends in water quality of each lake will be analyzed separately. A set of graphs are presented for each lake, including: TP, chlorophyll a, and Secchi disk transparency for both seasonal trends during the sampling period and for longer term trends; temperature and dissolved oxygen depth profiles from each sampling date; and algal community composition. This last set of graphs presents the percentages of each general taxonomic group for each sample. The algae are split into the following groups: blue-green algae, diatoms, yellow- brown algae, green algae, and “other.” The name “blue-green algae” is slightly misleading, in that these organisms are not actually algae. They are a group of bacteria, termed cyanobacteria, which
5 are able to photosynthesize. Due to this trait, they are grouped with algae, and often called algae, since they contribute to the amount of chlorophyll in an aquatic system. However, blue-green algae have a trait that sets them apart from the other algae, in that some forms can utilize atmospheric nitrogen, a form of nitrogen unavailable to other algae. Therefore, when dissolved nitrogen concentrations in the lake are low, blue-green algae have access to an additional source of nitrogen, and often dominate the algal community during those periods of the year when dissolved nitrogen concentrations in the lake are low, normally in late summer. Additionally, many groups of blue- green algae are not very edible to zooplankton, which graze on algae. While a bloom of blue-green algae in late summer is common in MN lakes, dominance by this form throughout the summer is not common and is often a sign of extreme nutrient enrichment.
The Minnesota Lake Eutrophication Analysis Procedure (MINLEAP) model was used to predict the TP concentration, chlorophyll a concentration, and Secchi disk transparency of each lake based on the lake area, lake depth, and the area of the lake’s watershed. A complete explanation of this model may be found in Wilson and Walker (1989). The predicted values were then compared to the observed values (summer means) for each lake. Further information on this model may be found in the MPCA website at: http://www.pca.state.mn.us/water/charting.html.
A subroutine in the MINLEAP model provided an estimate of background TP concentration for each lake based on its mean depth and alkalinity. This estimate was derived from an equation developed by Vighi and Chiaudani (1985) and is based on the morphoedaphic index commonly used in fisheries science. This equation assumes that most of the phosphorus entering the lake arises from soil erosion in the watershed, and that phosphorus and other minerals, which contribute to alkalinity, are delivered in relatively constant proportions. In turn, the mean depth of the lake will moderate the in-lake phosphorus concentration (e.g. deep lakes settle material readily, which contributes to low phosphorus concentrations).
6 Table 4. Mean summer water quality parameters and trophic status indicators, based on 2000 epilimnetic data. The “NCHF Ecoregion” range is the 25th – 75th percentile of summer means from ecoregion reference lakes. Chlorophyll a measurements have been corrected for phaeophytin. TSI percentiles are based on approximately 650 lakes in the NCHF ecoregion. See Figure 2 for an explanation of the TSI. NCHF Ann Gilchrist Grove Leven Reno Smith Villard Ecoregion Total phosphorus (µg/l) 264 73 34 45 49 55 32 23-50 Chlorophyll a (µg/l) 38 59 16 21 34 37 14 5-22 Chlorophyll a 107 96 32 39 110 67 24 7-37 maximum (µg/l) Secchi depth (m) 2.0 1.2 2.1 1.8 1.6 1.2 2.0 1.5-3.2 Total Kjeldahl 1.7 1.3 1.0 1.2 1.4 1.3 1.0 <.6-1.2 nitrogen (mg/l) Alkalinity (mg/l) 200 190 184 166 324 164 162 75-150 Color (Pt-Co) 12 18 16 20 10 14 16 10-20 pH 8.9 8.5 8.4 8.4 9.0 8.6 8.7 8.6-8.8 Total suspended 9.6 12.1 4.9 6.4 10.0 8.2 4.6 2-6 solids (mg/l) Total suspended 2.2 3.2 1.2 1.9 4.4 1.1 0.8 1-2 inorganic solids (mg/l) Conductivity 522 441 436 525 752 354 442 300-400 (µmhos/cm) TKN:TP 6 18 29 9 28 23 30 25-35 TSI, based on: TP 85 66 55 57 60 62 54 Chlor a 66 71 58 60 65 66 56 Secchi 50 57 49 52 54 57 50 TSI percentiles: TP 5-10 25-50 50-75 50-75 50-75 25-50 50-75 Chlor a 25-50 10-25 50-75 25-50 25-50 25-50 50-75 Secchi 50-75 25-50 50-75 50-75 25-50 25-50 50-75
Table 5. Lake morphometry and watershed areas. Mean depth and watershed areas were estimated for Ann, Leven, Reno and Villard Lakes. Ann Gilchrist Grove Leven Reno Smith Villard Maximum depth (ft) 14 24 31 33 25 36 15 Mean depth (ft) 10 10 9 15 15 15 10 Lake area (acres) 356 330 374 283 2612 581 536 Watershed area (mi2) 2.2 107 12.7 14.4 8.8 14.9 32.8 Watershed:lake area ratio 4:1 209:1 22:1 33:1 2:1 16:1 40:1
7 Figure 2. Carlson’s Trophic State Index, based on a scale of 0 – 100. (Carlson 1977)
TSI < 30 Classical Oligotrophy: Clear water, oxygen throughout the year in the hypolimnion, salmonid fisheries in deep lakes.
TSI 30 - 40 Deeper lakes still exhibit classical oligotrophy, but some shallower lakes will become anoxic in the hypolimnion during the summer.
TSI 40 - 50 Water moderately clear, but increasing probability of anoxia in hypolimnion during summer.
TSI 50 - 60 Lower boundary of classical eutrophy: Decreased transparency, anoxic hypolimnia during the summer, macrophyte problems evident, warm-water fisheries only.
TSI 60 - 70 Dominance of blue-green algae, algal scums probable, extensive macrophyte problems.
TSI 70 - 80 Heavy algal blooms possible throughout the summer, dense macrophyte beds, but extent limited by light penetration. Often would be classified as hypereutrophic.
TSI > 80 Algal scums, summer fish kills, few macrophytes, dominance of rough fish.
OLIGOTROPHIC MESOTROPHIC EUTROPHIC HYPEREUTROPHIC
20 25 30 35 40 45 50 55 60 65 70 75 80 TROPHIC STATE INDEX
15 10 8 7 6 5 4 3 2 1.5 1 0.5 0.3 SECCHI DEPTH (meters)
0.5 1 2 3 4 5 7 10 15 20 30 40 60 80 100 150 CHLOROPHYLL-A (µg/l)
3 5 7 10 15 20 25 30 40 50 60 80 100 150 TOTAL PHOSPHORUS (µg/l)
After Moore, L. and K. Thornton, [Ed.]1988. Lake and Reservoir Restoration Guidance Manual. USEPA>EPA 440/5-88-002.
NCHF Ecoregion Range, 25th – 75th percentile:
8 Gilchrist Lake
Gilchrist Lake is a moderate-sized (330 acres, 134 hectares) but shallow lake (mean depth of ten feet, or 3 meters) located on the East Branch of the Chippewa River. It has a very large watershed (~107 mi2) relative to its size (Table 5). As such, its water residence time (time it would take to fill the lake if it were completely empty) is quite short – on the order of 0.1 to 0.7 years. The river enters at the northern end of the lake (near the secondary site) and exits at the southern end (primary site, Figure 3). A LAP study was conducted on Gilchrist in conjunction with the lake association in 1992. Eurasian watermilfoil was confirmed to be present in the lake in 1996.
Gilchrist Lake was well mixed down to a depth of approximately three meters. By June 13, both temperature and dissolved oxygen began to drop off below three meters (Figure 5). By August 21, the water column was well mixed with regard to temperature; however, dissolved oxygen (DO) was still somewhat lower in the deeper layers of the lake. Based on these profiles Gilchrist exhibits intermittent stratification during the summer. Heavy winds or the passing of cold fronts would likely cause the lake to mix because of its shallow depth.
When compared to the NCHF reference lakes, Gilchrist Lake ranks below average in terms of water quality (Table 4). Average epilimnetic total phosphorus was 73 µg/L, well above the 75th percentile of 50 µg/L for the NCHF ecoregion. Compared to other “intermittent” mixing lakes in the NCHF it ranks between the 50th and 75th percentiles (Table 2). Phosphorus concentrations were lowest during the early summer, at 40 µg/L, and peaked at 90 µg/L during the sampling at the end of August (Figure 4). Chlorophyll a showed a similar trend. Accordingly, Secchi disk transparency was higher at the beginning of the summer, then dropped substantially and remained at less than one meter from late July through late September. TSI values suggest that Lake Gilchrist demonstrated eutrophic to hypereutrophic conditions during the period sampled (Table 4, Figure 2).
Blue-green algae dominated the algal community on all three sampling dates (Figure 6). In a “normal” seasonal progression of algae in this type of lake, diatoms dominate in the spring, followed by green algae, leading to a bloom of blue-green algae later on in the summer when dissolved nitrogen concentrations are lower. However, in Gilchrist Lake, the blue-greens made up 75% of the community in June, which is rather early for a blue-green algae bloom. This was also the case in the 1992 LAP study. The high nutrient concentrations and shallow depth of the lake, combined with warm temperatures, likely caused the dominance of blue-greens. Gilchrist Lake is classified as “partially supporting” for swimmable use, due to high algal concentrations, frequent algal blooms and low transparency which may limit swimming for a significant portion of the summer.
The trophic status in 2000 was quite comparable to the historical data for the lake (Figure 4). Based on available information TP typically ranges from about 60 to 75 µg/L in most years. Chlorophyll a varied from about 20 to over 60 µg/L and Secchi was typically between 1 to 1.5 m in most summers (Figure 4).
Table 6 provides a comparison of the predicted TP concentrations based on the MINLEAP model and the observed measurements from the 2000 monitoring study. Based on
9 this comparison, the lake exhibits a slightly lower TP concentration than would be anticipated based on the lake’s size and the size of its watershed. This may be due to upstream lakes and wetlands that serve to trap phosphorus. As a result, the phosphorus load to the lake is lower than that predicted by the model. The model estimated a background TP concentration of 29 µg/L based on the lake’s mean depth and alkalinity.
Table 6. MINLEAP results for Gilchrist Lake (± 1 SE). Observed Predicted TP (µg/L) 73 (±7.5) 100 (±23) Chl a (µg/L) 59 (±10) 55 (±26) Secchi (m) 1.2 (±0.2) 0.7 (±0.3)
Figure 3. Bathymetric map of Gilchrist Lake.
10 Figure 4. Seasonal and long-term trends in mean TP, chlorophyll a, and Secchi depth, in Lake Gilchrist. Error bars represent 1 standard error. Note that “year” on the x-axis is not consecutive.
120 0
100 1 Secchi (m) 80 2
60
3 40
4 20 TP, chlorophyll a (ug/l) 0 5 May Jun Jul Aug Sep Oct
Summer 2000
120 0
TP 1 Chlor a 100 Secchi 2
3 Secchi (m) 80 4
60 5
6 40 7
8 20 9 TP, chlorophyll a (ug/l) 0 10
1955 1974 1977 1980 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
Annual
11 Figure 5. Temperature and dissolved oxygen (DO) depth profiles of Gilchrist Lake, 2000.
Temperature (°C)
14 16 18 20 22 24 0
2
4
6 Depth (m)
8 June 5 June 13 10 July 25 Aug 21 DO (mg/L) Sept 12
024681012 0
2
4
6 Depth (m) Depth
8
10
Figure 6. Algal composition for Gilchrist Lake, 2000.
100% 80% Other 60% Green Yellow -brow n 40% Diatoms 20% Blue-green
% composition % 0% June July August
12 Reno Lake
Reno Lake is located north of Glenwood, on the Pope and Douglas County border. It is a large (2,612 acres; 1,057 hectares) but rather shallow lake, with a maximum depth of approximately 25 feet (7.6 meters) and a majority of the lake basin at 15 feet (4.6 meters) or less (Figure 7). Its watershed is relatively small as compared to the size of the lake (Table 5); the watershed area is approximately 2278 hectares (8.8 mi2). Two sites in the lake were sampled in 2000, both at a depth of 20 feet (6.1 meters).
Reno Lake was quite well mixed during the summer of 2000 (Figure 9). This is a result of its shallow depth and large fetch (maximum distance wind can travel unimpeded). Temperatures peaked at about 23°C in July. DO concentrations were generally above 7 mg/L throughout the water column, though some declines were evident just above the sediments.
TP concentrations were just within the typical range for minimally impacted lakes in the NCHF ecoregion (Table 4) and the lake ranked near the 25th percentile for well-mixed (polymictic) lakes in the NCHF ecoregion (Table 2). Chlorophyll a was high in comparison to the reference lakes and relative to Reno’s TP concentration; hence the chlorophyll a-TSI was relatively high as compared to the TP-TSI for the lake (Table 5). The phosphorus and chlorophyll levels were rather high during the late August sampling event (Figure 8), leading to the high summer averages for those parameters. The maximum chlorophyll a of 110 µg/L was the highest of all these lakes in 2000 (Table 4). TSI values ranged from 54 to 65, indicating eutrophic conditions (Table 4, Figure 2). Reno Lake is classified as having “partial support” for swimmable use, indicating that algal blooms and low transparency may limit swimming for a significant portion of the summer.
Similar to Gilchrist Lake, blue-green algae dominated the algal community at Reno Lake on all three sampling dates (Figure 10). In June, blue-greens comprised 80% of the community, dropping somewhat to 65% by the August sampling date. Similar to Gilchrist Lake, the high nutrient concentrations, shallow depth, and high temperatures likely contributed to the dominance by the blue-greens.
Some historic data from Pope Coalition of Lake Associations (COLA) monitoring was available for comparison. The measured TP in 2000 was quite comparable to Pope COLA data from 1994 to 1997; however the 2000 chlorophyll a was much higher than the previous data (Figure 8). Secchi ranged from about 1.5 to 2.5 m in most years based on data dating back to 1991. No trend is evident based on this data.
The predicted (based on the MINLEAP model) and the observed trophic status values are summarized in Table 7. The observed TP and chlorophyll a concentrations in the lake were both slightly higher than the respective values predicted by the model. This suggests that nutrient loading to the lake may be higher than anticipated based on the lake’s size, depth and size of its watershed. In addition, the model estimated a background TP concentration of 31 µg/L based on the lake’s mean depth and alkalinity. This value is not significantly different from the
13 MINLEAP prediction; however, it is less than the observed TP. Thus the “background” or anticipated TP for the lake is in the 24 – 30 µg/L range, which is less than the 2000 MPCA and recent COLA data for the lake.
Table 7. MINLEAP results for Reno Lake (± 1 SE). Observed Predicted TP (µg/L) 49 (±9.5) 24 (±10) Chl a (µg/L) 34 (±14) 7.0 (±4.9) Secchi (m) 1.6 (±0.3) 2.5 (±1.1)
Figure 7. Bathymetric map of Reno Lake
14 Figure 8. Seasonal and long-term trends in mean TP, chlorophyll a, and Secchi depth, in Reno Lake. Error bars represent 1 standard error.
0 120
100 1 Secchi (m)
80 TP 60 2 Chl a Secchi
40 3 20
0 4 TP, chlorophyll a (ug/l) May Jun Jul Aug Sep Oct
Summer 2000
120 0
1 100 2
3 Secchi (m) 80 4
60 5
6 40 7
8 20 9 TP, chlorophyll a (ug/l) chlorophyll TP, 0 10 2 4 1991 199 1993 199 1995 1996 1997 1998 1999 2000
Annual
15 Figure 9. Temperature and dissolved oxygen (DO) depth profiles of Reno Lake, 2000.
Temperature (°C)
14 16 18 20 22 24 0
2
4
Depth (m) 6
8 June 5 June 14 July 26 10 Aug 22 Sept 12 DO (mg/L)
678910 0
2
4
Depth (m) 6
8
10
Figure 10. Algal community composition at Reno Lake in 2000.
100% 80% Other Green 60% Yellow-brown 40% Diatoms Blue-green 20% % composition % 0% June July August
16 Ann Lake
Ann Lake is a moderate sized lake (surface area of 356 acres) located south of Reno Lake. The lake is shallow, with a maximum depth of ten feet (three meters; Table 5). It has a relatively small watershed (1436 acres, 2.2 mi2) and receives runoff from John Lake to the west.
Ann Lake was well mixed throughout the summer of 2000. Temperatures peaked in July at 23 degrees C (Figure 13). DO concentrations were at or above 6.5 mg/L on all dates.
The water quality values exceeded the typical range for most of the measured parameters (Table 4). Total phosphorus was the highest of all of the lakes monitored in this study (264 µg/L; Table 4), and chlorophyll a was also relatively high, with a summer-mean of 38 µg/L and maximum of 107 µg/L. These values characterize Ann as a hypereutrophic lake, according to the TSI (Table 4, Figure 2). Total Kjeldahl nitrogen (TKN) was quite high as well (Table 4). Due to high levels of phosphorus and frequent algal blooms, swimming is considered “non- supported” in Ann Lake (MPCA 2000).
Blue-green algae dominated the algal community on all sampling dates (Figure 14), and comprised 100% of the community during the August sampling. The blue-green algae, which typically form scums near the surface of the lake, allowed for deeper transparency than would be expected based on the TP and chlorophyll a values (Table 5).
Total phosphorus concentrations increased steadily over the summer of 2000 (Figure 12). This was likely caused by a combination of phosphorus loading from the watershed and internal recycling of phosphorus, which is common in shallow, hypereutrophic lakes. Chlorophyll a peaked near 100 µg/L in late August, coincident with the peak in TP.
The total phosphorus and chlorophyll record over the last decade is scarce; however, the Secchi depth record is more complete. The average Secchi depth from 2000 is near the long term average, monitored since 1992 (Figure 12).
The predicted (MINLEAP) and observed water quality parameters are outlined in Table 8. The observed summer-mean TP was significantly greater than the predicted TP concentration. This discrepancy suggests that the lake may be receiving excessive nutrient loading from the watershed, which is surprising considering the lake’s relatively small watershed size. The observed chlorophyll a concentration was also higher than predicted; however, this difference was anticipated based on the high observed TP. Note that the watershed area is relatively small (581 hectares) relative to the surface area of the lake (144 hectares).
Table 8. MINLEAP results for Ann Lake (± 1 SE). Observed Predicted TP (µg/L) 264 (±58) 35 (±14) Chl a (µg/L) 38 (±18) 12 (±8) Secchi (m) 2.0 (±0.1) 1.8 (±0.8)
17 Figure 11. Bathymetric map of Ann Lake.
18 Figure 12. Seasonal and long-term trends in mean TP, chlorophyll a, and Secchi depth, in Ann Lake. Error bars represent 1 standard error for years with more than one observation.
500 0
400 3 Secchi (m)
300 6
200 9
100 12 TP, chlorophyll a (ug/l)
0 15 May Jun Jul Aug Sep Oct
TP Chl a Secchi
Summer 2000
450 0
400 1
350 2
3 Secchi (m) 300 4 250 5 200 6 150 7
100 8
50 9 TP, chlorophyll a (ug/l) 0 10 2 7 9 99 994 996 998 000 1 1993 1 1995 1 199 1 199 2
Annual
19 Figure 13. Temperature and dissolved oxygen (DO) depth profiles of Ann Lake, 2000.
Temperature (°C)
14 16 18 20 22 24 0
2
4
Depth (m) Depth 6
8 June 5 June 14 July 26 10 Aug 22 Sept 12 DO (mg/L)
45678910 0
2
4
Depth (m) Depth 6
8
10
Figure 14. Algal community composition in Ann Lake in 2000.
100%
80% Other 60% Green 40% Yellow -green Diatoms 20% Blue-green % composition % 0% June July August
20 Grove Lake
Grove Lake, located in the eastern portion of Pope County, has a surface area of 374 acres, a maximum depth of 31 feet (9.4 meters), and a mean depth of almost nine feet (2.7 meters; Table 5). It is one of the two lakes in this survey that is not part of the Minnesota River basin, but rather is located in the Upper Mississippi River basin, at the headwaters of the North Fork of the Crow River. The river feeds into the lake towards the eastern end of its northern shore, exits at the eastern end of the southern shore (Figure 15), and drains a watershed of about 12.7 square miles. Grove Lake was one of MPCA’s ecoregion reference lakes and was monitored from 1985-1987 as a part of this statewide effort. It was also the subject of a Clean Water Partnership (CWP) Phase I and II effort. The diagnostic study was conducted in 1986 and was the subject of an MA thesis “A Limnologic Diagnostic Study of Grove Lake, Pope County in 1986” (Munter-Holm 1988).
The primary monitoring site for the 2000 monitoring was located in the eastern part of the lake, near the inflow and outflow of the river, and the secondary site was located towards the center of the lake (consistent with previous efforts). Grove Lake was thermally stratified by mid- June, and remained stratified through the end of August (Figure 17). Dissolved oxygen was quite low (< 2 mg/L) in the hypolimnion (lower cooler layer) through the end of August as well.
Most of the water quality parameters fell within the 25th to 75th percentile ranges of the NCHF ecoregion (Table 4). Grove Lake and Villard Lake were the only lakes in this study that ranked above the median value for all three TSI estimates (Table 4), lending them a classification of mesotrophic to eutrophic. Unlike many of the other lakes sampled for this study, there was not a peak in total phosphorus towards the end of the summer; rather phosphorus levels remained low (relative to this set of lakes) throughout the summer (Figure 16). Hypolimnetic TP peaked at 355 µg/L at the end of August, just before fall turnover in September. Based on trophic status data since 1994, swimming in Grove Lake is considered to be fully supported.
In June, the algae were composed of a mixed community of yellow-browns, diatoms, and blue-greens (Figure 18). During the July and August sampling dates blue-green algae dominated; however, several other forms were still present in the samples. The transition between algal forms was more typical of what is anticipated for lakes – in contrast to the dominance of blue-greens in Reno, Ann and Gilchrist Lakes.
Grove Lake has an excellent long-term database as a result of CLMP, MPCA, and lake association and watershed district efforts. During our reference lake monitoring in the 1980s TP ranged between approximately 40 to 45 µg/L and chlorophyll a ranged from about 17 to 22 µg/L. With the exception of what appears to be an outlier value for 1990 (based on high standard error), the trend in TP has been stable to declining in recent years. Chlorophyll a exhibited a similar trend (Figure 16). Secchi in most years ranges from about 1.5 to 2.1 m with some slightly higher measurements in the early 1980s.
MINLEAP modeling was conducted for Grove Lake based on the 2000 observed data and morphometric and watershed data compiled during MPCA’s reference lake work (Table 9). Grove Lake’s observed TP was slightly less than that predicted by MINLEAP; loading to the
21 lake was likely lower than that predicted by the model. Likewise, chlorophyll a was lower and Secchi was higher. The lower observed TP may reflect trapping of TP in upstream lakes or wetlands. The “background” P for Grove Lake was estimated at 30 µg/L, which is quite close to the 2000 observed concentration.
Table 9. MINLEAP results for Grove Lake (± 1 SE). Observed Predicted TP (µg/L) 34 (±3.4) 59(±19) Chl a (µg/L) 16 (±3) 25 (±15) Secchi (m) 2.1 (±0.4) 1.2 (±0.5)
Figure 15. Bathymetric map of Grove Lake.
22 Figure 16. Seasonal and long-term trends in mean TP, chlorophyll a, and Secchi depth, in Grove Lake. Error bars represent 1 standard error.
70 0
1 60 2 Secchi (m) Secchi 50 3
4 40 5 30 6
20 7 8 10 9
TP, chlorophyll a (ug/l) chlorophyll TP, 0 10 May Jun Jul Aug Sep Oct
TP Chl a Secchi
Summer 2000
120 0
1 100 2
3 Secchi (m) 80 4
60 5
6 40 7
8 20 9 TP, chlorophyll (ug/l) a 0 10 3 1982198 1984 19851986 198719881989 19901991 199219931994 19951996 199719981999 2000
Annual
23 Figure 17. Temperature and dissolved oxygen (DO) depth profiles of Grove Lake, 2000.
Temperature (°C)
14 16 18 20 22 24 26 0
2
4
Depth (m) Depth 6
8 June 5 June 13 July 25 10 Aug 21 Sept 12
DO (mg/L)
0246810 0
2
4
Depth (m) Depth 6
8
10
Figure 18. Community composition at Grove Lake in 2000.
100% 80% Other 60% Green Yellow -brow n 40% Diatoms 20% Blue-green
% composition % 0% June July August
24 Leven Lake
Leven Lake is located north of Villard Lake and drains directly into it. Leven Lake is fed by a stream that enters the north-eastern part of the lake and its watershed reaches northward into Douglas County. It has a total surface area of 283 acres, a maximum depth of 33 feet (10.1 meters), and a watershed area of approximately 3734 ha (14.4 mi2; Table 5).
Leven Lake is one of the deeper lakes in this study, and was thermally stratified by mid- June, similar to the other deep lakes (Figure 25). The lake remained stratified throughout the summer, but by mid-September the water column was isothermic (same temperature top to bottom). During the July 25 sampling, the hypolimnion was anoxic, with dissolved oxygen concentrations below 2 mg/L. The lake remained this way through August, after which dissolved oxygen in the hypolimnion increased due to fall turnover which was underway on the September sampling date.
Total phosphorus and chlorophyll a in Leven Lake were near the upper end of the “typical range” for lakes in the NCHF ecoregion (Table 4). Hypolimnetic TP peaked at 468 µg/L during the end of July, and remained quite high (367 µg/L) at the end of August, before fall turnover. Turnover contributed to the increase in TP between the August and September sampling events (Figure 24). Leven Lake is considered eutrophic to hypereutrophic based on its TSI values. The moderately high TP and chlorophyll a classify the lake as “partially supporting” for swimmable use, implying that algal blooms may impair swimming for a portion of the summer.
Blue-green algae comprised 90% of the algal community during the June sampling, and remained high throughout the summer (Figure 26). Based on elevated chlorophyll a and dominance of blue-greens, nuisance blooms were likely common in 2000. This dominance of blue-greens likely contributed to the higher than anticipated Secchi values.
TP values were quite variable between years and no overall pattern is evident. Summer- mean TP and chlorophyll a in 2000 was comparable to COLA monitoring from 1994 to 1997 (Figure 24). Secchi disk transparency remained relatively stable from 1992 - 2000 (Figure 24).
Lake Leven’s watershed is quite large in relation to its surface area (Table 5). However, the observed TP concentration in the lake was not significantly different from the concentration predicted by the MINLEAP model (Table 10). Based on the model, the lake retained approximately 63% of its phosphorus load. This phosphorus retention in Leven benefits Lake Villard, located immediately downstream from Leven. The estimated background phosphorus (based on the Vighi and Chiaudani regression) was 25 µg/L. Based on the two model estimates, the observed phosphorus concentration in 2000 in Leven seemed reasonable. However, the background phosphorus estimate suggests there may be room for some reduction.
25 Table 10. MINLEAP results for Leven Lake (± 1 SE). Observed Predicted TP (µg/L) 45 (±6) 57(±18) Chl a (µg/L) 21 (±6) 25 (±14) Secchi (m) 1.8 (±0.4) 1.2 (±0.5)
Figure 23. Bathymetric map of Leven Lake.
26 Figure 24. Seasonal and long-term trends in mean TP, chlorophyll a, and Secchi depth, in Leven Lake. Error bars represent 1 standard error.
70 0
1 60 2 Secchi (m) 50 3
4 40 5 (ug/l) 30 a 6
20 7 8 10 9
TP, chlorophyll 0 10 May Jun Jul Aug Sep Oct
TP Chl a Secchi
Summer 2000
200 0
180 1
160 2
140 3 Secchi (m)
120 4
100 5
80 6
60 7
40 8
20 9
TP, chlorophyll a (ug/l) chlorophyll TP, 0 10
92 4 19 1993 199 1995 1996 1997 1998 1999 2000
Annual
27 Figure 25. Temperature and dissolved oxygen (DO) depth profiles of Leven Lake, on all sampling dates in 2000.
Temperature (°C)
14 16 18 20 22 24 26 0
2
4
Depth (m) 6
8 June 5 June 13 July 25 10 August 21 Sept 12 DO (mg/L)
2468 0
2
4
Depth (m) 6
8
10 0 10
.
Figure 26. Algal community composition at Leven Lake in 2000.
100%
80% Other 60% Green Yellow -brow n 40% Diatoms 20% Blue-green % composition % 0% June July August
28 Lake Villard
Lake Villard is a shallow lake located in the north-eastern portion of Pope County, just south of Leven Lake. It outlets to Lake Amelia directly to the south, and is part of the headwaters of the East Branch of the Chippewa River, in the Minnesota River basin. The lake’s surface area is 536 acres, with a maximum depth of 15 feet (4.6 meters) and a mean depth of ten feet (three meters; Table 5, Figure 19). Its watershed, approximately 8500 ha (32.8 mi2), extends to the northwest and into Douglas County. There are at least four inflows to the lake including Rice Lake (Figure 19).
Villard Lake did not thermally stratify during the monitoring period. Dissolved oxygen concentrations were generally above 7 mg/L and fairly constant from surface to bottom, though some reduction in DO was noted near the bottom of the lake (Figure 21).
Water quality parameters were well within the typical range for reference lakes in the NCHF ecoregion (Table 4; Figure 20). Additionally, as previously mentioned, it is one of two lakes in this study that ranks above the ecoregion median values for all three of the TSIs calculated (Table 4). These TSIs place Villard Lake as a mesotrophic to eutrophic lake. Relative to other well-mixed lakes, it ranks near the 10th percentile in terms of TP (Table 2). Based on recent (1995 forward) data, swimming is fully supported.
The June algal community was dominated by yellow-brown algae (Figure 22). In July, approximately 50% of the algae were blue-greens, 25% were diatoms, and the remaining 25% were other forms. The community in August was similar to the July community. Again, as with Grove Lake, a much more typical transition in algal types was noted over the summer.
Total phosphorus concentrations in the lake have not changed substantially since 1995; however, the levels measured since then are all well below the average phosphorus concentrations reported in 1980 and 1994 (Figure 20). There appears to be a slight trend of improved water clarity (as measured by Secchi disk transparency) since 1992 and chlorophyll a concentrations have been 15 µg/L or less since 1995.
Similar to Lake Leven, Lake Villard’s watershed is large relative to the size of the lake. It also exhibited an observed TP which was less than the predicted (Table 11). This can be explained by the phosphorus retention in Lake Leven, since approximately 44% of Lake Villard’s watershed drains through Leven. The MINLEAP model does not take upstream nutrient retention into account, and therefore the predicted TP concentration was greater than the observed concentration. Likewise, the predicted Secchi transparency was less than that observed. The background phosphorus was estimated at 28 µg/L, slightly lower than the observed concentration.
Table 11. MINLEAP results for Villard Lake (± 1 SE). Observed Predicted TP (µg/L) 32 (±6) 69 (±20) Chl a (µg/L) 14 (±4) 32 (±18) Secchi (m) 2.0 (±0.4) 1.0 (±0.4)
29 Figure 19. Bathymetric map of Villard Lake.
30 Figure 20. Seasonal and long-term trends in mean TP, chlorophyll a, and Secchi depth, in Villard Lake. Error bars represent 1 standard error. Note that “year” on the x-axis is not consecutive.
70 0
1 60 2 Secchi (m) 50 3
4 40 5 (ug/l) 30 a 6
20 7 8 10 9
TP, chlorophyll 0 10 May Jun Jul Aug Sep Oct TP Chl a Secchi
Summer 2000
120 0
1 100 2 Secchi (m)
3 80 4
60 5
6 40 7
8 20 9
0 10 TP, chlorophyll a (ug/l) 3 0 0 5 60 8 92 993 94 995 97 998 0 19 19 1975 19 19 1 19 1 1996 19 1 1999 20
Annual
31 Figure 21. Temperature and dissolved oxygen (DO) depth profiles of Villard Lake, 2000.
Temperature (°C)
14 16 18 20 22 24 0
2
4
Depth (m) 6
8
June 5 10 June 13 July 25 Aug 21 Sept 12 DO (mg/L)
45678910 0
2
4
Depth (m) Depth 6
8
10
Figure 22. Algal community composition at Villard Lake in 2000.
100%
80% Other 60% Green 40% Yellow -brow n Diatoms 20% Blue-green % composition % 0% June July August
32 Smith Lake
Smith Lake, located in the south-eastern portion of Douglas County, has a total surface area of 581 acres, a maximum depth of 36 feet (11.0 meters), and a mean depth of 15 feet (4.6 meters; Table 5). It has a fairly large watershed area of approximately 14.9 square miles (3850 ha). Smith Lake was included in MPCA reference lake monitoring of the 1980s.
The water column was stratified by mid-June, and by the end of August was undergoing fall turnover (Figure 29). In mid-June, dissolved oxygen concentrations were lower in the hypolimnion, and this pattern was more pronounced during the July and August sampling events. September profile data were not available.
Most of the water quality parameters exceeded the 25th to 75th percentile range for NCHF ecoregion reference lakes (Table 4). TP peaked at the end of July at 65 µg/L (Figure 28), with a concurrent peak in chlorophyll (55 µg/L). Hypolimnetic TP peaked at 128 µg/L at the end of July, and remained high (99 µg/L) at the end of August. TSI values agree fairly well and classify Smith Lake as eutrophic. Based on the elevated TP, high chlorophyll a and low Secchi, swimming is non-supported (Table 4; Figure 2).
The algal community was dominated by blue-green algae on all sampling dates, ranging from 85% of the community in June to 95% in August (Figure 30). Nuisance blue-green algae blooms were common in late summer. This was similar to other the more eutrophic lakes in this study.
The only historical data were from the MPCA monitoring in the 1980’s. A mean TP of 62 µg/L, chlorophyll a of 29 µg/L, and Secchi of 1.4 m from that effort was comparable to the measures recorded in 2000 (Table 4). No CLMP data were available for the lake.
MINLEAP modeling for Smith Lake was performed based on lake morphometric and watershed data from the reference lake work and the 2000 data. These modeling results indicate a slightly higher observed TP than predicted by the model (Table 12). Chlorophyll a was substantially higher than predicted. The background TP was estimated at 25 µg/L. Thus based on the observed and predicted TP and chlorophyll a values for Smith Lake, some reduction in TP may be possible and desirable.
Table 12. MINLEAP results for Smith Lake (± 1 SE). Observed Predicted TP (µg/L) 55 (±11) 45 (±16) Chl a (µg/L) 37 (±7) 17 (±11) Secchi (m) 1.2 (±0.2) 1.5 (±0.6)
33 Figure 27. Bathymetric map of Smith Lake.
34 Figure 28. Seasonal and long-term trends in mean TP, chlorophyll a, and Secchi depth, in Smith Lake. Error bars represent 1 standard error.
80 0
1 70 2
60 Secchi (m) 3 50 4
40 5 (ug/l)
a 6 30 7 20 8 10 9
TP, chlorophyll 0 10 May Jun Jul Aug Sep Oct
TP Chl a Secchi
35 Figure 29. Temperature and dissolved oxygen (DO) depth profiles of Smith Lake, 2000.
Temperature (°C)
14 16 18 20 22 24 0
2
4
6 Depth (m) 8
10
12 June 5 June 14 July 26 Aug 22 DO (mg/L)
024681012 0
2
4
6 Depth (m) Depth 8
10
12
Figure 30. Algal community composition at Smith Lake in 2000.
100% 80% Other 60% Green Yellow -brow n 40% Diatoms 20% Blue-green
% composition % 0% June July August
36 Summary
During the summer of 2000, six lakes in eastern Pope and Douglas Counties were sampled by the MPCA as a part of its regional and trend monitoring efforts. Of these, Grove, Smith and Gilchrist had been previously monitored by the MPCA as a part of the ecoregion reference lake and/or LAP monitoring efforts. Grove, Gilchrist, Reno, Leven, and Villard Lakes have been monitored as a part of Pope County Water Plan and COLA efforts as well. In contrast, Ann Lake had virtually no data beyond CLMP Secchi data.
Following are a few general observations and recommendations based on our monitoring and data analysis:
A. Secchi transparency monitoring: All lakes, with the exception of Smith, have participated in CLMP. Monitoring Secchi transparency provides a good basis for estimating trophic status and detecting trends. Routine participation is essential to allow for trend analysis. Of these lakes, Gilchrist, Reno, Ann, Grove, Leven and Villard have eight or more years of data (minimum needed for trend analysis). Continued CLMP monitoring on these lakes will contribute to the data base which already exists. It would be beneficial to have CLMP monitoring on Smith as well, which would augment the MPCA data and allow for future trend assessments.
B. Water quality and tropic status: Based on data collected in 2000, Grove and Villard exhibited TP and chlorophyll a concentrations comparable to the typical range for minimally- impacted lakes in the NCHF ecoregion. These lakes are considered “mildly eutrophic.” Leven and Reno were near the upper limit of this range and are considered eutrophic. Smith and Gilchrist TP concentrations were above the range and chlorophyll a was quite high. Both are considered highly eutrophic. Ann Lake exhibited very high TP and chlorophyll a and is considered “hypereutrophic.”
C. Water quality trends: Of the lakes with sufficient Secchi data for trend analysis, only Reno, with eight previous years of data (1991 to 1998), exhibited a significant (p = 0.05) positive trend for these years. It is unclear, however, whether this signifies a long-term trend in condition of the lake since Secchi in 2000 was somewhat lower and TP was equal to or greater than data from 1994 to 1997. Leven and Villard posted a non-significant increase in transparency. Grove Lake, which has the most extensive data record, exhibited a decline in TP and chlorophyll a when the years 1985 to 1987 (TP mean = 43 and chl a mean = 20 µg/L) are compared to the more recent time period from 1996 to 2000 (TP mean = 32 and chl a mean = 11 µg/L). Continued monitoring of all of these lakes will enhance our ability to assess trends.
D. Model predictions: In general, MINLEAP model results for Leven, Reno, Ann, and Smith suggest that observed TP was higher than predicted based on the lakes’ sizes, depths and watershed areas. Since these were based on estimated watershed areas and mean depths (Leven, Reno, and Ann), it is possible that there is some error incorporated in these estimates. Actual delineation of watershed boundaries and planimetry of lake volumes would improve these model estimates. For Leven, Reno, and Smith, the predicted and observed TP concentrations are relatively close; however, the observed TP for Ann is
37 significantly higher than the predicted TP, suggesting excessive phosphorus loading from the watershed.
Model predictions for Gilchrist, Villard and Grove were all higher than the observed concentrations. This is most likely a result of upstream trapping of phosphorus in lakes (e.g. Leven) and wetlands which is not accounted for in the MINLEAP model. However, in all cases the “background” phosphorus (based on the Vighi and Chiaudani regression) was lower than observed concentrations and suggests some reduction in in-lake phosphorus may be possible.
38 References
Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography 22:361-369.
Heiskary, S. H., and C. B. Wilson. 1988. Minnesota lake water quality assessment report. Minnesota Pollution Control Agency.
McCollor, S. and S. H. Heiskary. 1993. Selected water quality characteristics of minimally impacted streams from Minnesota’s seven ecoregions. MPCA. St. Paul MN
Munter-Holm, S. 1988. A limnologic diagnostic study of Grove Lake, Pope County, Minnesota in 1986. MA Thesis, St. Cloud State University.
Vighi, M. and G. Chiaudani. 1985. A simple method to estimate lake phosphorus concentrations resulting from natural background loading. Water Res. 19: 987-991.
Wilson, C. B. and W.W. Walker, Jr. 1989. Development of lake assessment methods based upon the aquatic ecoregion concept. Lake and Reservoir Management 5:11-22.
39 Appendix A – 2000 water quality data for Pope County lakes (K=actual value is less than the specified value for that parameter)
Lake Date Top Bot Site Secchi Color Alk TSS TSV TKN TP Chl a Phaeo (m) (m) (m) (pt-co) (ppm) (ppm) (ppm) (ppm) (ppm) (ppb) (ppb) 29 78 80 410 530 535 625 665 32211 32218 Ann 61-0122 05-Jun-00 0.0 2.0 101 2.1 10 190 6.8 4.4 1.25 0.137 18.8 1.4 61-0122 14-Jun-00 0.0 2.0 101 2.4 10 200 4.0 2.4 1.26 0.147 7.1 2.4 61-0122 26-Jul-00 0.0 2.0 101 1.8 10 190 6.0 4.0 1.38 0.234 18.9 1.8 61-0122 22-Aug-00 0.0 2.0 101 1.9 20 200 16.0 14.0 2.48 0.416 107.0 12.5 61-0122 12-Sep-00 0.0 2.0 101 1.8 10 220 15.0 12.0 1.92 0.384 36.1 1.6 Gilchrist 61-0072 05-Jun-00 0.0 2.0 101 2.6 10 200 4.8 3.6 0.88 0.051 17.1 2.8 61-0072 05-Jun-00 0.0 2.0 102 2.7 0.061 14.9 3.7 61-0072 13-Jun-00 0.0 2.0 101 1.3 20 210 6.8 5.0 1.04 0.038 25.1 0.5 K 61-0072 13-Jun-00 0.0 2.0 102 0.9 0.045 48.9 0.5 K 61-0072 25-Jul-00 0.0 2.0 101 0.7 20 170 14.0 10.0 1.33 0.069 54.6 5.9 61-0072 25-Jul-00 0.0 2.0 102 0.7 0.107 96.7 8.9 61-0072 21-Aug-00 0.0 2.0 101 0.8 20 180 13.0 10.0 1.80 0.093 75.2 6.7 61-0072 21-Aug-00 0.0 2.0 102 0.7 0.083 73.1 6.2 61-0072 12-Sep-00 0.0 2.0 102 0.9 0.097 96.3 5.2 Grove 61-0023 05-Jun-00 0.0 2.0 101 4.6 10 180 2.8 2.0 0.81 0.018 2.4 0.3 K 61-0023 05-Jun-00 0.0 2.0 102 4.7 0.024 3.0 1.1 61-0023 13-Jun-00 0.0 2.0 101 2.4 20 190 2.8 2.4 0.88 0.051 9.8 0.5 K 61-0023 13-Jun-00 7.0 7.0 101 0.020 61-0023 13-Jun-00 0.0 2.0 102 1.9 0.021 13.0 0.5 K 61-0023 25-Jul-00 0.0 2.0 101 1.2 20 170 6.4 4.4 0.95 0.034 18.6 2.1 61-0023 25-Jul-00 7.0 7.0 101 0.087 61-0023 25-Jul-00 0.0 2.0 102 1.3 0.036 15.2 2.1 61-0023 21-Aug-00 0.0 2.0 102 1.3 0.034 15.7 3.6 61-0023 21-Aug-00 8.0 8.0 101 0.355 61-0023 12-Sep-00 0.0 2.0 101 1.2 10 190 7.2 5.6 1.07 0.044 32.3 2.1 61-0023 12-Sep-00 0.0 2.0 102 1.4 0.044 30.0 4.4 Leven 61-0066 05-Jun-00 0.0 2.0 101 2.0 20 170 8.4 4.0 0.94 0.043 13.8 2.1 61-0066 13-Jun-00 0.0 2.0 101 3.2 20 190 2.4 2.0 1.14 0.028 6.1 13.4 61-0066 13-Jun-00 7.0 7.0 101 0.024 61-0066 25-Jul-00 0.0 2.0 101 1.6 20 160 6.0 4.0 1.03 0.054 18.6 1.7 61-0066 25-Jul-00 8.0 8.0 101 0.468 61-0066 21-Aug-00 0.0 2.0 101 1.1 20 160 6.8 5.2 1.42 0.041 27.8 2.9 61-0066 21-Aug-00 9.0 9.0 101 0.367 61-0066 12-Sep-00 0.0 2.0 101 1.1 20 150 8.4 7.2 1.27 0.060 38.8 6.3 Reno 61-0078 05-Jun-00 0.0 2.0 101 3.1 10 310 3.6 2.4 1.01 0.016 2.4 0.3 61-0078 05-Jun-00 0.0 2.0 102 3.1 0.019 2.8 0.3 61-0078 14-Jun-00 0.0 2.0 101 1.4 10 330 6.0 2.4 1.12 0.025 4.4 1.3 61-0078 14-Jun-00 0.0 2.0 102 1.9 0.022 2.1 0.5 K 61-0078 26-Jul-00 0.0 2.0 101 1.3 10 310 5.2 2.8 1.12 0.042 6.4 1.1 61-0078 26-Jul-00 0.0 2.0 102 1.5 0.045 5.0 1.3 61-0078 22-Aug-00 0.0 2.0 101 0.7 10 340 15.0 12.0 2.57 0.085 99.6 6.2 61-0078 22-Aug-00 0.0 2.0 102 0.8 0.091 110.0 11.2 61-0078 12-Sep-00 0.0 2.0 101 0.9 10 330 20.0 8.4 1.19 0.057 38.2 5.2 61-0078 12-Sep-00 0.0 2.0 102 0.9 0.090 70.5 14.2
40 Lake Date Top Bot Site Secchi Color Alk TSS TSV TKN TP Chl a Phaeo (m) (m) (m) (pt-co) (ppm) (ppm) (ppm) (ppm) (ppm) (ppb) (ppb) Smith 21-0016 05-Jun-00 0.0 2.0 101 2.4 10 170 5.2 4.0 0.83 0.026 8.0 1.4 21-0016 05-Jun-00 0.0 2.0 102 2.1 0.026 8.0 0.3 K 21-0016 14-Jun-00 0.0 2.0 101 1.7 10 170 4.4 3.6 0.90 0.029 16.3 1.1 21-0016 14-Jun-00 8.0 8.0 101 0.024 21-0016 14-Jun-00 0.0 2.0 102 0.038 21.0 0.4 K 21-0016 26-Jul-00 0.0 2.0 101 0.7 20 170 10.0 8.8 1.44 0.067 57.2 4.3 21-0016 26-Jul-00 8.5 8.5 101 0.128 21-0016 26-Jul-00 0.0 2.0 102 0.7 0.146 66.8 5.1 21-0016 22-Aug-00 0.0 2.0 101 0.8 10 150 12.0 10.0 1.83 0.066 55.6 8.1 21-0016 22-Aug-00 10.0 10.0 101 0.099 21-0016 22-Aug-00 0.0 2.0 102 0.9 0.052 49.5 5.6 21-0016 12-Sep-00 0.0 2.0 101 0.9 20 160 9.6 9.2 1.30 0.049 46.7 1.8 21-0016 12-Sep-00 0.0 2.0 102 0.9 0.047 43.3 3.0 Villard 61-0067 05-Jun-00 0.0 2.0 101 3.4 10 170 2.8 2.4 0.79 0.019 6.1 1.1 61-0067 13-Jun-00 0.0 2.0 101 2.4 10 160 2.0 1.6 0.91 0.022 9.8 0.5 K 61-0067 25-Jul-00 0.0 2.0 101 1.8 20 160 3.2 2.0 0.95 0.034 8.3 2.0 61-0067 21-Aug-00 0.0 2.0 101 1.1 20 160 8.0 6.8 1.12 0.052 24.4 6.5 61-0067 12-Sep-00 0.0 2.0 101 1.2 20 160 7.2 6.4 1.12 0.035 19.7 2.3
41 Appendix B – 2000 profile data for Pope County lakes
Lake Date Time Depth Site Temp DO SpCond pH ORP DO (hhmm) (meters) (øC) (mg/l) (æS/cm) (mV) (% sat) Ann 61-0122 05-Jun-00 1000 0.1 101 17.6 9.4 61-0122 05-Jun-00 1000 1.0 101 16.3 9.3 61-0122 05-Jun-00 1000 2.0 101 15.9 9.3 61-0122 05-Jun-00 1000 3.0 101 15.8 9.3 61-0122 05-Jun-00 1000 4.0 101 15.8 8.8 61-0122 05-Jun-00 1000 5.0 101 15.7 6.0
61-0122 14-Jun-00 0915 0.1 101 20.7 7.5 467 9.2 137 84.9 61-0122 14-Jun-00 0915 1.1 101 20.7 7.5 467 9.2 137 84.9 61-0122 14-Jun-00 0915 2.0 101 20.7 7.5 467 9.3 136 84.8 61-0122 14-Jun-00 0915 2.9 101 20.6 7.4 467 9.2 136 83.5 61-0122 14-Jun-00 0915 4.0 101 20.6 7.4 467 9.2 136 83.0
61-0122 26-Jul-00 0900 0.2 101 22.9 7.2 454 8.9 189 86.0 61-0122 26-Jul-00 0900 0.2 101 22.9 7.2 454 8.9 189 86.0 61-0122 26-Jul-00 0900 1.0 101 22.9 7.1 453 8.9 189 85.4 61-0122 26-Jul-00 0900 2.0 101 22.8 6.9 453 8.9 190 82.9 61-0122 26-Jul-00 0900 3.0 101 22.8 6.4 454 8.8 190 75.1 61-0122 26-Jul-00 0900 4.0 101 22.8 4.4 458 8.7 192 53.2
61-0122 22-Aug-00 1010 0.2 101 21.8 6.9 457 8.8 150 80.5 61-0122 22-Aug-00 1010 0.2 101 21.8 6.8 457 8.8 149 79.6 61-0122 22-Aug-00 1010 1.0 101 21.9 6.7 457 8.8 149 78.8 61-0122 22-Aug-00 1010 2.0 101 21.8 6.6 458 8.8 149 77.6 61-0122 22-Aug-00 1010 3.1 101 21.8 6.5 458 8.8 149 76.7 61-0122 22-Aug-00 1010 4.0 101 21.7 6.2 459 8.8 149 71.9
61-0122 12-Sep-00 1145 0.0 101 18.6 9.6 707 8.7 369 61-0122 12-Sep-00 1145 1.0 101 18.6 9.1 707 8.7 368 61-0122 12-Sep-00 1145 2.0 101 18.6 9.1 708 8.7 368 61-0122 12-Sep-00 1145 3.0 101 18.5 9.1 709 8.8 365 61-0122 12-Sep-00 1145 4.0 101 18.5 9.0 709 8.8 364 61-0122 12-Sep-00 1145 4.4 101 18.5 8.8 709 8.8 361
Gilchrist 61-0072 05-Jun-00 1110 0.1 101 20.1 8.0 61-0072 05-Jun-00 1110 1.0 101 17.9 8.5 61-0072 05-Jun-00 1110 2.0 101 16.8 8.3 61-0072 05-Jun-00 1110 3.0 101 16.5 7.7 61-0072 05-Jun-00 1110 4.0 101 16.2 7.6 61-0072 05-Jun-00 1110 5.0 101 16.1 7.8 61-0072 05-Jun-00 1110 6.0 101 15.8 7.8 61-0072 05-Jun-00 1110 6.5 101 15.8 4.5
61-0072 13-Jun-00 1215 0.3 101 21.6 9.1 427 9.0 96 104.5 61-0072 13-Jun-00 1215 1.3 101 21.5 9.0 426 9.0 96 103.7 61-0072 13-Jun-00 1215 1.9 101 21.5 9.0 426 9.2 97 103.0 61-0072 13-Jun-00 1215 3.1 101 20.9 7.5 431 8.8 99 85.6 61-0072 13-Jun-00 1215 4.1 101 18.9 6.7 448 8.5 103 68.7 61-0072 13-Jun-00 1215 5.3 101 17.0 4.2 455 8.2 108 39.4
42 Lake Date Time Depth Site Temp DO SpCond pH ORP DO (hhmm) (meters) (øC) (mg/l) (æS/cm) (mV) (% sat) 61-0072 13-Jun-00 1215 6.0 101 16.4 1.6 458 8.1 19 16.2
61-0072 25-Jul-00 1230 0.1 101 23.1 9.5 380 8.4 294 114.4 61-0072 25-Jul-00 1230 0.9 101 23.0 9.8 381 8.5 292 116.8 61-0072 25-Jul-00 1230 2.1 101 22.3 8.1 384 8.3 296 93.8 61-0072 25-Jul-00 1230 3.0 101 22.2 7.6 384 8.3 296 90.2 61-0072 25-Jul-00 1230 4.0 101 22.1 6.9 387 8.2 298 81.0 61-0072 25-Jul-00 1230 5.0 101 21.6 2.8 397 7.8 310 31.3 61-0072 25-Jul-00 1230 6.1 101 21.3 1.1 403 7.6 310 10.5
61-0072 21-Aug-00 1145 0.2 101 21.9 8.6 371 8.5 198 100.8 61-0072 21-Aug-00 1145 1.0 101 21.6 7.8 372 8.4 198 91.0 61-0072 21-Aug-00 1145 2.0 101 21.5 6.6 375 8.2 199 76.4 61-0072 21-Aug-00 1145 3.0 101 21.4 6.2 375 8.2 199 71.6 61-0072 21-Aug-00 1145 4.0 101 21.4 5.8 376 8.2 198 67.0 61-0072 21-Aug-00 1145 5.0 101 21.3 5.5 376 8.1 198 64.0 61-0072 21-Aug-00 1145 6.0 101 21.2 5.1 377 8.1 199 58.7
61-0072 12-Sep-00 1320 0.1 101 19.4 9.9 563 9.0 342 61-0072 12-Sep-00 1320 1.0 101 19.4 9.8 563 9.0 343 61-0072 12-Sep-00 1320 2.0 101 19.3 9.8 563 9.0 345 61-0072 12-Sep-00 1320 3.0 101 19.2 9.8 564 9.0 346 61-0072 12-Sep-00 1320 4.0 101 18.9 9.6 563 8.9 345 61-0072 12-Sep-00 1320 5.0 101 18.6 9.0 566 8.9 347 61-0072 12-Sep-00 1320 5.9 101 18.1 7.8 567 8.8 347
Grove 61-0023 05-Jun-00 1255 0.1 101 19.5 7.6 61-0023 05-Jun-00 1255 1.0 101 17.8 7.6 61-0023 05-Jun-00 1255 2.0 101 16.7 7.6 61-0023 05-Jun-00 1255 3.0 101 16.1 7.6 61-0023 05-Jun-00 1255 4.0 101 16.0 7.5 61-0023 05-Jun-00 1255 5.0 101 15.7 7.4 61-0023 05-Jun-00 1255 6.0 101 15.7 7.4 61-0023 05-Jun-00 1255 7.0 101 15.6 7.1 61-0023 05-Jun-00 1255 8.0 101 15.2 3.7 61-0023 05-Jun-00 1255 9.0 101 14.9 1.6
61-0023 13-Jun-00 1440 10.0 101 21.3 9.2 408 8.9 114 104.5 61-0023 13-Jun-00 1440 1.2 101 21.3 9.2 407 8.9 113 104.9 61-0023 13-Jun-00 1440 2.9 101 21.2 9.1 407 8.9 112 104.4 61-0023 13-Jun-00 1440 4.0 101 20.1 8.0 411 8.7 115 88.6 61-0023 13-Jun-00 1440 5.0 101 18.4 7.5 418 8.5 117 80.7 61-0023 13-Jun-00 1440 5.8 101 16.8 5.9 417 8.4 120 60.9 61-0023 13-Jun-00 1440 7.1 101 15.6 4.2 422 8.2 123 38.8 61-0023 13-Jun-00 1440 7.9 101 15.0 1.3 429 8.1 14 11.5
61-0023 25-Jul-00 1349 0.1 101 23.6 9.4 362 8.6 247 113.7 61-0023 25-Jul-00 1349 1.0 101 23.5 9.4 362 8.6 245 113.7 61-0023 25-Jul-00 1349 2.0 101 23.3 9.3 362 8.6 244 112.1 61-0023 25-Jul-00 1349 3.1 101 23.1 9.2 363 8.6 243 111.1 61-0023 25-Jul-00 1349 4.0 101 23.1 9.0 363 8.6 242 107.9 61-0023 25-Jul-00 1349 5.1 101 22.8 8.3 365 8.5 242 99.0 61-0023 25-Jul-00 1349 5.9 101 20.6 1.9 399 7.8 223 21.2
43 Lake Date Time Depth Site Temp DO SpCond pH ORP DO (hhmm) (meters) (øC) (mg/l) (æS/cm) (mV) (% sat) 61-0023 25-Jul-00 1349 6.9 101 18.1 0.7 425 7.6 50 7.5 61-0023 25-Jul-00 1349 8.0 101 17.1 0.5 433 7.6 -111 5.4 61-0023 25-Jul-00 1349 8.8 101 16.4 0.4 446 7.5 -162 3.5
61-0023 21-Aug-00 1300 0.2 101 23.2 6.8 357 8.3 163 81.6 61-0023 21-Aug-00 1300 0.9 101 22.2 6.7 357 8.4 163 78.7 61-0023 21-Aug-00 1300 1.9 101 22.1 6.7 357 8.4 163 78.2 61-0023 21-Aug-00 1300 3.0 101 22.0 6.6 357 8.4 163 77.8 61-0023 21-Aug-00 1300 4.0 101 22.0 6.6 357 8.4 162 77.9 61-0023 21-Aug-00 1300 5.0 101 22.0 6.6 356 8.4 162 77.1 61-0023 21-Aug-00 1300 5.9 101 21.5 1.8 374 7.9 167 21.2 61-0023 21-Aug-00 1300 7.0 101 18.5 0.9 431 7.6 -98 8.7 61-0023 21-Aug-00 1300 8.0 101 17.4 0.3 445 7.7 -162 3.4
61-0023 12-Sep-00 1445 0.1 101 19.3 8.0 563 8.6 334 61-0023 12-Sep-00 1445 1.0 101 19.3 7.9 563 8.5 336 61-0023 12-Sep-00 1445 2.0 101 19.2 7.8 563 8.5 338 61-0023 12-Sep-00 1445 3.0 101 19.2 7.8 563 8.5 338 61-0023 12-Sep-00 1445 4.0 101 19.2 7.8 563 8.5 336 61-0023 12-Sep-00 1445 5.0 101 19.2 7.8 563 8.5 335 61-0023 12-Sep-00 1445 6.0 101 19.2 7.9 563 8.5 335 61-0023 12-Sep-00 1445 7.0 101 19.2 7.9 563 8.5 334 61-0023 12-Sep-00 1445 8.0 101 19.1 7.8 563 8.5 333 61-0023 12-Sep-00 1445 8.3 101 19.1 7.7 563 8.4 204
Leven 61-0066 05-Jun-00 1440 0.1 101 17.9 9.8 61-0066 05-Jun-00 1440 1.0 101 16.8 10.0 61-0066 05-Jun-00 1440 2.0 101 16.3 9.9 61-0066 05-Jun-00 1440 3.0 101 16.3 9.7 61-0066 05-Jun-00 1440 4.0 101 16.2 9.4 61-0066 05-Jun-00 1440 5.0 101 16.1 8.4 61-0066 05-Jun-00 1440 6.0 101 15.9 7.2 61-0066 05-Jun-00 1440 7.0 101 15.8 7.1 61-0066 05-Jun-00 1440 8.0 101 15.6 5.8 61-0066 05-Jun-00 1440 9.0 101 15.6 3.9 61-0066 05-Jun-00 1440 9.5 101 15.4 2.1
61-0066 13-Jun-00 1600 0.2 101 21.4 8.2 494 8.9 105 93.9 61-0066 13-Jun-00 1600 1.4 101 21.4 8.2 495 8.9 105 93.9 61-0066 13-Jun-00 1600 2.1 101 21.4 8.1 494 8.9 105 93.1 61-0066 13-Jun-00 1600 3.2 101 21.1 8.3 474 8.7 110 89.0 61-0066 13-Jun-00 1600 3.7 101 19.4 7.7 498 8.7 108 82.6 61-0066 13-Jun-00 1600 5.1 101 16.2 6.9 504 8.3 113 68.5 61-0066 13-Jun-00 1600 6.0 101 15.8 4.8 506 8.2 114 49.5 61-0066 13-Jun-00 1600 7.0 101 15.5 3.8 512 8.1 116 34.2 61-0066 13-Jun-00 1600 7.8 101 15.5 1.3 512 8.1 114 13.3
61-0066 25-Jul-00 1530 0.1 101 23.7 8.8 458 8.4 285 106.7 61-0066 25-Jul-00 1530 0.1 101 23.7 8.8 457 8.4 284 106.7 61-0066 25-Jul-00 1530 1.0 101 23.6 8.8 457 8.4 281 107.2 61-0066 25-Jul-00 1530 2.0 101 23.5 8.7 456 8.5 279 105.2 61-0066 25-Jul-00 1530 2.9 101 23.1 7.9 455 8.4 278 95.2 61-0066 25-Jul-00 1530 3.9 101 22.4 6.2 463 8.2 279 73.4
44 Lake Date Time Depth Site Temp DO SpCond pH ORP DO (hhmm) (meters) (øC) (mg/l) (æS/cm) (mV) (% sat) 61-0066 25-Jul-00 1530 5.0 101 21.2 1.5 481 7.7 284 14.8 61-0066 25-Jul-00 1530 6.1 101 20.2 0.4 500 7.7 94 4.5 61-0066 25-Jul-00 1530 7.0 101 18.6 0.3 519 7.7 -98 2.9 61-0066 25-Jul-00 1530 7.8 101 17.6 0.3 524 7.5 -153 2.3 61-0066 25-Jul-00 1530 8.8 101 17.1 0.2 530 7.5 -190 2.1
61-0066 21-Aug-00 1425 0.2 101 22.6 8.7 431 8.4 120 103.8 61-0066 21-Aug-00 1425 0.2 101 22.7 8.7 431 8.4 120 103.5 61-0066 21-Aug-00 1425 1.0 101 22.3 8.8 431 8.5 121 103.7 61-0066 21-Aug-00 1425 2.0 101 21.8 8.2 432 8.4 123 95.6 61-0066 21-Aug-00 1425 3.0 101 21.7 7.7 434 8.3 124 89.8 61-0066 21-Aug-00 1425 4.0 101 21.6 7.4 434 8.3 126 85.8 61-0066 21-Aug-00 1425 5.0 101 21.5 7.0 435 8.5 127 81.6 61-0066 21-Aug-00 1425 6.0 101 21.3 5.4 443 8.2 129 64.4 61-0066 21-Aug-00 1425 7.0 101 19.1 1.5 523 7.6 -156 14.8 61-0066 21-Aug-00 1425 8.0 101 18.0 0.8 536 7.5 -212 8.7 61-0066 21-Aug-00 1425 9.0 101 17.4 0.5 545 7.5 -247 5.5
61-0066 12-Sep-00 1630 0.0 101 18.9 9.0 658 8.9 311 61-0066 12-Sep-00 1630 1.0 101 18.9 8.8 658 8.8 312 61-0066 12-Sep-00 1630 2.0 101 18.9 8.9 658 8.8 314 61-0066 12-Sep-00 1630 3.0 101 18.8 8.8 658 8.8 315 61-0066 12-Sep-00 1630 4.0 101 18.8 8.7 658 8.8 315 61-0066 12-Sep-00 1630 5.0 101 18.6 8.0 660 8.7 317 61-0066 12-Sep-00 1630 6.0 101 18.5 7.8 661 8.7 317 61-0066 12-Sep-00 1630 7.0 101 18.5 7.8 661 8.6 318 61-0066 12-Sep-00 1630 8.0 101 18.4 7.3 662 8.6 319 61-0066 12-Sep-00 1630 8.8 101 18.1 6.6 665 8.5 233
Reno 61-0078 05-Jun-00 1630 0.1 101 18.2 8.0 61-0078 05-Jun-00 1630 1.0 101 17.2 8.1 61-0078 05-Jun-00 1630 2.0 101 16.0 8.4 61-0078 05-Jun-00 1630 3.0 101 15.7 8.4 61-0078 05-Jun-00 1630 4.0 101 15.4 8.5 61-0078 05-Jun-00 1630 5.0 101 15.3 8.5 61-0078 05-Jun-00 1630 6.0 101 15.2 7.7 61-0078 05-Jun-00 1630 7.0 101 15.1 7.1
61-0078 14-Jun-00 0830 0.2 101 19.8 8.2 678 9.2 150 89.4 61-0078 14-Jun-00 0830 1.1 101 19.8 7.9 678 9.2 150 86.7 61-0078 14-Jun-00 0830 2.1 101 19.8 7.7 678 9.2 150 85.9 61-0078 14-Jun-00 0830 2.9 101 19.8 7.7 678 9.2 150 85.5 61-0078 14-Jun-00 0830 4.0 101 19.7 7.6 678 9.2 150 84.7 61-0078 14-Jun-00 0830 4.9 101 19.7 7.6 678 9.2 150 84.4 61-0078 14-Jun-00 0830 6.2 101 19.7 7.5 678 9.2 150 83.5
61-0078 14-Jun-00 0810 0.1 102 19.7 7.7 677 9.2 152 85.4 61-0078 14-Jun-00 0810 1.0 102 19.7 7.8 678 9.2 152 86.3 61-0078 14-Jun-00 0810 2.0 102 19.7 7.8 678 9.2 152 86.0 61-0078 14-Jun-00 0810 3.1 102 19.7 7.7 677 9.2 152 85.7 61-0078 14-Jun-00 0810 3.9 102 19.7 7.7 678 9.2 152 84.9
61-0078 26-Jul-00 0825 0.2 101 23.0 7.7 670 8.8 234 91.8
45 Lake Date Time Depth Site Temp DO SpCond pH ORP DO (hhmm) (meters) (øC) (mg/l) (æS/cm) (mV) (% sat) 61-0078 26-Jul-00 0825 0.3 101 23.0 7.6 670 8.8 234 91.6 61-0078 26-Jul-00 0825 1.1 101 23.0 7.9 669 8.8 234 95.2 61-0078 26-Jul-00 0825 2.0 101 23.0 8.1 669 8.8 233 97.3 61-0078 26-Jul-00 0825 3.0 101 23.0 8.2 669 8.8 233 98.7 61-0078 26-Jul-00 0825 4.0 101 23.0 8.3 669 8.8 232 99.1 61-0078 26-Jul-00 0825 5.0 101 23.0 8.3 670 8.8 232 99.3 61-0078 26-Jul-00 0825 6.0 101 22.8 6.5 676 8.7 233 77.1
61-0078 22-Aug-00 0935 0.2 101 21.6 9.6 656 9.1 150 112.4 61-0078 22-Aug-00 0935 1.0 101 21.6 9.5 657 9.1 150 110.5 61-0078 22-Aug-00 0935 2.0 101 21.5 9.3 658 9.1 150 108.1 61-0078 22-Aug-00 0935 3.0 101 21.4 8.1 660 9.0 151 93.2 61-0078 22-Aug-00 0935 4.0 101 21.4 7.6 660 9.0 151 88.2 61-0078 22-Aug-00 0935 5.0 101 21.3 7.5 660 9.0 151 87.1 61-0078 22-Aug-00 0935 5.9 101 21.3 7.6 660 9.0 151 88.1
61-0078 12-Sep-00 1710 0.1 101 18.6 8.7 1000 9.0 325 61-0078 12-Sep-00 1710 1.0 101 18.7 8.8 1000 9.0 323 61-0078 12-Sep-00 1710 2.0 101 18.6 8.8 1001 9.0 324 61-0078 12-Sep-00 1710 3.0 101 18.7 8.7 1001 9.0 324 61-0078 12-Sep-00 1710 4.0 101 18.6 8.7 1001 9.0 324 61-0078 12-Sep-00 1710 5.1 101 18.6 8.7 1001 9.0 324 61-0078 12-Sep-00 1710 6.0 101 18.6 8.5 1002 9.0 324 61-0078 12-Sep-00 1710 6.1 101 18.6 8.4 1002 9.0 319
Smith 21-0016 05-Jun-00 1810 0.1 101 19.6 8.8 21-0016 05-Jun-00 1810 1.0 101 17.9 9.8 21-0016 05-Jun-00 1810 2.0 101 16.4 9.9 21-0016 05-Jun-00 1810 3.0 101 16.2 9.8 21-0016 05-Jun-00 1810 4.0 101 16.1 9.1 21-0016 05-Jun-00 1810 5.0 101 16.1 8.7 21-0016 05-Jun-00 1810 6.0 101 16.0 8.4 21-0016 05-Jun-00 1810 7.0 101 15.8 7.6 21-0016 05-Jun-00 1810 8.0 101 15.7 7.0 21-0016 05-Jun-00 1810 9.0 101 15.5 0.9
21-0016 14-Jun-00 1040 0.1 101 20.2 9.0 345 9.3 131 100.0 21-0016 14-Jun-00 1040 1.1 101 19.9 8.9 345 9.3 132 98.6 21-0016 14-Jun-00 1040 2.1 101 19.9 8.9 345 9.3 132 98.2 21-0016 14-Jun-00 1040 3.1 101 19.9 8.8 346 9.3 132 97.6 21-0016 14-Jun-00 1040 4.2 101 19.8 8.8 345 9.3 132 97.9 21-0016 14-Jun-00 1040 5.2 101 18.4 7.6 351 9.0 135 81.4 21-0016 14-Jun-00 1040 5.8 101 16.8 6.2 355 8.7 139 64.5 21-0016 14-Jun-00 1040 7.2 101 16.4 5.0 357 8.6 140 52.1 21-0016 14-Jun-00 1040 8.2 101 16.0 4.2 358 8.4 142 41.8 21-0016 14-Jun-00 1040 9.0 101 15.8 3.3 360 8.5 115 33.8
21-0016 26-Jul-00 1015 0.2 101 22.7 7.8 347 8.7 162 93.4 21-0016 26-Jul-00 1015 1.1 101 22.6 8.0 347 8.7 163 94.8 21-0016 26-Jul-00 1015 2.0 101 22.5 7.9 347 8.7 164 93.2 21-0016 26-Jul-00 1015 3.0 101 22.5 7.7 347 8.7 165 91.2 21-0016 26-Jul-00 1015 4.0 101 22.5 7.5 347 8.6 166 88.6 21-0016 26-Jul-00 1015 5.0 101 22.4 7.3 348 8.6 167 85.6
46 Lake Date Time Depth Site Temp DO SpCond pH ORP DO (hhmm) (meters) (øC) (mg/l) (æS/cm) (mV) (% sat) 21-0016 26-Jul-00 1015 6.0 101 22.3 6.2 350 8.5 169 72.5 21-0016 26-Jul-00 1015 7.0 101 21.3 2.9 357 8.0 174 32.5 21-0016 26-Jul-00 1015 7.9 101 20.9 1.2 360 7.9 176 12.6 21-0016 26-Jul-00 1015 9.0 101 20.0 0.3 372 8.1 97 2.6
21-0016 22-Aug-00 1115 0.2 101 22.2 8.9 342 8.8 141 105.6 21-0016 22-Aug-00 1115 1.0 101 22.2 9.0 342 8.8 142 106.1 21-0016 22-Aug-00 1115 2.0 101 22.1 8.3 343 8.7 144 97.3 21-0016 22-Aug-00 1115 3.0 101 21.7 6.2 346 8.5 147 72.5 21-0016 22-Aug-00 1115 4.0 101 21.6 5.8 347 8.4 148 66.7 21-0016 22-Aug-00 1115 5.0 101 21.6 4.5 348 8.3 149 51.7 21-0016 22-Aug-00 1115 6.0 101 21.6 5.1 347 8.4 149 59.2 21-0016 22-Aug-00 1115 7.0 101 21.5 3.7 350 8.2 151 43.2 21-0016 22-Aug-00 1115 8.1 101 21.4 2.8 351 8.0 152 30.7 21-0016 22-Aug-00 1115 9.1 101 21.2 1.6 354 7.9 154 17.8 21-0016 22-Aug-00 1115 10.0 101 20.9 0.3 366 7.8 148 3.4 21-0016 22-Aug-00 1115 11.0 101 17.6 0.1 488 7.2 -153 1.1
Villard 61-0067 05-Jun-00 1545 0.1 101 18.5 8.7 61-0067 05-Jun-00 1545 1.0 101 16.9 8.7 61-0067 05-Jun-00 1545 2.0 101 16.2 8.7 61-0067 05-Jun-00 1545 3.0 101 15.9 8.7 61-0067 05-Jun-00 1545 4.0 101 15.9 8.7 61-0067 05-Jun-00 1545 4.5 101 15.9 7.9
61-0067 13-Jun-00 1520 0.1 101 21.6 7.7 449 8.8 131 88.1 61-0067 13-Jun-00 1520 0.6 101 21.6 7.6 449 8.8 130 86.9 61-0067 13-Jun-00 1520 2.0 101 21.5 7.6 448 8.8 129 87.3 61-0067 13-Jun-00 1520 2.9 101 21.4 7.5 448 8.8 129 86.3 61-0067 13-Jun-00 1520 3.9 101 21.4 6.7 447 8.6 90 69.9
61-0067 25-Jul-00 1450 0.1 101 23.2 8.3 399 8.3 285 99.9 61-0067 25-Jul-00 1450 1.0 101 23.2 8.5 399 8.3 283 101.9 61-0067 25-Jul-00 1450 2.0 101 23.2 8.4 399 8.3 278 100.8 61-0067 25-Jul-00 1450 3.0 101 23.1 8.4 399 8.4 276 100.5 61-0067 25-Jul-00 1450 3.7 101 23.0 4.7 398 8.1 199 50.7
61-0067 21-Aug-00 1350 0.2 101 22.4 8.9 369 8.7 115 104.8 61-0067 21-Aug-00 1350 1.0 101 21.5 9.2 368 8.7 117 106.8 61-0067 21-Aug-00 1350 2.0 101 21.3 9.3 365 8.8 117 107.9 61-0067 21-Aug-00 1350 3.0 101 21.2 9.1 366 8.7 119 105.2 61-0067 21-Aug-00 1350 4.0 101 21.1 7.8 368 8.6 122 90.0
61-0067 12-Sep-00 1540 0.0 101 18.4 9.0 553 9.0 310 61-0067 12-Sep-00 1540 1.0 101 18.4 8.8 553 8.9 312 61-0067 12-Sep-00 1540 2.0 101 18.4 8.8 553 8.9 314 61-0067 12-Sep-00 1540 3.0 101 18.3 8.8 553 8.9 315 61-0067 12-Sep-00 1540 4.0 101 18.3 8.7 553 8.9 314 61-0067 12-Sep-00 1540 4.2 101 18.3 8.8 554 8.9 301
47 Appendix C – Glossary
Acid rain: Rain with a higher than normal acid range (low pH). Caused when polluted air mixes with cloud moisture. Can devoid lakes of fish.
Algal bloom: An unusual or excessive abundance of algae.
Alkalinity: Capacity of a lake to neutralize acid.
Bioaccumulation: Build-up of toxic substances in fish flesh (fatty tissues). Toxic effects may be passed on to humans eating the fish.
Biomanipulation: Adjusting the fish species composition in a lake as a restoration technique.
Dimictic: A lake which undergoes two annual periods of mixing, once in the spring and once in the fall, and goes through a period of both summer stratification and winter inverse stratification.
Ecoregion: Geographic areas of relative homogeneity. EPA ecoregions have been defined for Minnesota based on land use, soils, landform, and potential natural vegetation.
Ecosystem: A community of interaction among animals, plants, and micro-organisms, and the physical and chemical environment in which they live.
Epilimnion: Most lakes form three distinct layers of water during summertime weather. The epilimnion is the upper layer and is characterized by warmer and lighter water. Also known as the mixed layer.
Eutrophication: The aging process by which lakes are fertilized with nutrients. Natural eutrophication will very gradually change the character of a lake. Cultural eutrophication is the accelerated aging of a lake as a result of human activities.
Eutrophic Lake: A nutrient-rich lake – usually shallow, “green” and with limited oxygen in the bottom layer of water.
Fall turnover: Cooling surface waters, activated by wind action, sink and mix with lower layers of water. As in spring turnover, all water is now at the same temperature.
Hypolimnion: The bottom layer of lake water during a lake’s summer stratification period. The water in the hypolimnion is denser and much colder than the water in the upper two layers.
Intermittently stratified: A lake that intermittently stratifies during the summer. Common in shallow lakes.
Lake management: A process that involves study, assessment of problems, and decisions on how to maintain a lake as a thriving ecosystem.
Lake restoration: Actions directed toward improving the quality of a lake.
Lake stewardship: An attitude that recognizes the vulnerability of lakes and the need for citizens, both individually and collectively, to assume responsibility for their care.
Limnetic community: The area of open water in a lake providing the habitat for phytoplankton, zooplankton and fish.
Littoral community: The shallow areas around a lake’s shoreline, dominated by aquatic plants. The plants produce oxygen and provide food and shelter for animal life.
48 Mesotrophic lake: Midway in nutrient levels between the eutrophic and oligotrophic lakes.
Nonpoint source: Polluted runoff – nutrients and pollution sources not discharged from a single point: e.g. runoff from agricultural fields or feedlots.
Oligotrophic lake: A relatively nutrient- poor lake, it is clear and deep with bottom waters high in dissolved oxygen. pH scale: A measure of acidity. Waters with a low pH are more acidic.
Photosynthesis: The process by which green plants produce biomass and energy from sunlight, water and carbon dioxide, and in doing so produce oxygen.
Phytoplankton: Algae that live in the open water of a lake. They are often the base of a lake’s food chain. As algae, they produce oxygen as a by-product of photosynthesis.
Point sources: Specific sources of nutrient or polluted discharge to a lake: e.g. stormwater outlets.
Polymictic: A lake that does not thermally stratify in the summer and is continually mixed due to wind and wave action.
Profundal community: The area below the limnetic zone where light does not penetrate. This area roughly corresponds to the hypolimnion (bottom layer of water in a stratified lake) and is home to organisms that break down or consume organic matter.
Respiration: The process by which organisms convert biomass into energy. Respiration consumes oxygen.
Secchi disk: A device measuring the depth of light penetration in water.
Sedimentation: This addition of soils to lakes, a part of the natural aging process, makes lakes shallower. The process can be greatly accelerated by human activities.
Spring turnover: After ice melts in spring, warming surface water sinks to mix with the deeper water. At this time of year, all water is the same temperature.
Thermocline: During summertime, the middle layer of lake water, below the epilimnion. In the thermocline, there is a strong decrease in temperature with respect to depth.
Total Kjeldahl nitrogen (TKN): One measure of the amount of nitrogen in water, which includes all forms of organic nitrogen plus ammonium. TKN thus includes all forms of nitrogen except nitrate and nitrite.
Total suspended volatiles: A measure of the amount of suspended organic matter in a water sample. At high temperature, the organic matter becomes “volatile” and is driven off as a gas.
Trophic status: The level of growth or productivity of a lake as measured by phosphorus content, algal abundance, and depth of light penetration.
Turbidity: Particles in solution (e.g. soil or algae) which scatter light and reduce transparency.
Water density: Water is most dense at 39°F (4°C) and expands (becomes less dense) at both higher and lower temperatures.
Watershed: The land area that drains into a lake, river or river system.
Zooplankton: Microscopic animals that live in the open water of a lake.
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