Advancing Volunteer Lake Monitoring on Lake Vermilion – St. Louis County

Citizen Lake Monitoring Program: Advancing Volunteer Lake Monitoring on Lake Vermilion – St. Louis County

2008 Assessment Report March, 2009

Minnesota Pollution Control Agency 520 Lafayette Road North Saint Paul, MN 55155-4194 http://www.pca.state.mn.us 651-296-6300 or 800-657-3864 toll free TTY 651-282-5332 or 800-657-3864 toll free Available in alternative formats

Report Prepared By: Jesse Anderson – MPCA Duluth Office Steve Heiskary – MPCA St. Paul Office

Report Review: Dana Vanderbosch- MPCA St. Paul Office Johanna Schussler- MPCA St. Paul Office

With Cooperation From: • The Sportsmen’s Club of Lake Vermilion • Minnesota Department of Natural Resources, Tower Area Fisheries

Lake Vermilion CLMP+ Water Quality Report • March 2009 2 Minnesota Pollution Control Agency

Table of Contents List of Tables ...... 4

List of Figures...... 4

Executive Summary...... 5

Introduction...... 7

Background...... 8 Lake Assessment Overview ...... 8 a. Lake Trophic Status...... 8 b. Lake Morphometry and Mixing ...... 11 Study Area Overview...... 12 c. Watershed, and Land Use Characteristics ...... 14 d. Precipitation and Lake Levels...... 18 e. Fisheries Summary ...... 20

Methods...... 22

Results and Discussion...... 24

2008 Water Quality Summary ...... 32

Trophic Status and Water Quality Trends...... 37

Modeling...... 41

303(d) Assessment and Goal Setting ...... 47

References ...... 49

Appendices A Glossary ...... 50 B Water Quality Data Abbreviations and Units...... 52 C Water Quality Data ...... 53

Lake Vermilion CLMP+ Water Quality Report • March 2009 3 Minnesota Pollution Control Agency

LIST OF TABLES

1. 2008 Lake Vermilion Water Quality Monitoring Stations...... 7 2. Lake Vermilion Morphology ...... 14 3. Lake Vermilion Watershed Areas...... 14 4. Lake Vermilion Land Use Data ...... 16 5. MDH Laboratory Methods and Precision Estimates...... 23 6. 2008 Summer-mean Water Quality Data and NLF Ecoregion Typical Range ...... 33 7. Comparison of Observed and Model Predicted Values ...... 42 8. 2008 and 2000 Estimated Lake Vermillion Total Phosphorus Budget from BATHTUB Model………….45 9. Minnesota Lake Eutrophication Standards…………………………………………………………………48 10. Lake Vermilion 303d Assessment Summary……………………………………………………………...48

LIST OF FIGURES

1. Map of 2008 Lake Vermilion monitoring sites...... 7 2. Carlson’s Trophic State Index ...... 9 3. Minnesota’s Ecoregions...... 10 4. Mixing Types and Lake Layers for Shallow and Deep Lakes ...... 11 5. Monthly Mean Total Phosphorus, Chlorophyll-a and Secchi. Based on 30 shallow lakes sampled from West-Central MN in 2003...... 12 6. Lake Vermilion Watershed ...... 15 7. Lake Vermilion Watershed Land Cover ...... 17 8. Spring 2008 and 2008 Water Year Precipitation Totals ...... 18 9. 2008 Lake Vermilion Lake Levels…………………………………………………………………………19 10. 1994 to 2008 Lake Vermilion Water Levels……………………………………………………………….19 11. Pike Bay Temperature and DO Profile…………………………………………………………………….24 12. Big Bay Temperature and DO Profile……………………………………………………………………..25 13. Armstrong Bay Temperature and DO Profile……………………………………………………………...26 14. Frazer Bay Temperature and DO Profile…………………………………………………………………..27 15. Trout Lake Portage Temperature and DO Profile………………………………………………………….28 16. Niles Bay Temperature and DO Profile……………………………………………………………………29 17. Wakemup Bay Temperature and Oxygen Profile………………………………………………………….30 18. Head of the Lakes Bay Temperature and DO Profile……………………………………………………...31 19. TSI Values for Pike Bay and Entire Lake Vermilion Basin……………………………………………….34 20. 2008 Total Phosphorus, Chlorophyll-a and Secchi Transparency Data for east end sites…………………35 21. 2008 Total Phosphorus, Chlorophyll-a and Secchi Transparency Data for west end sites……………….36 22. Summer-mean total phosphorus, chlorophyll-a, and Secchi for 2000 and 2008…………………………..38 23. Trends in August chlorophyll-a concentrations at DNR’s Wakemup Bay site……………………………39 24. Trends in Lake Vermilion Secchi Transparency Data for: site 203, 218, and lake-wide average…………40 25. 2000 and 2008 estimated relative phosphorus contributions from external sources………………………46

Lake Vermilion CLMP+ Water Quality Report • March 2009 4 Minnesota Pollution Control Agency

Executive Summary

In 2008, the Minnesota Pollution Control Agency (MPCA) and the Sportsmen’s Club of Lake Vermilion (SCLV) partnered to conduct a water quality assessment on Lake Vermilion. This Advanced Citizen Lake Monitoring Program effort monitored 8 sites spread out across the lake’s numerous bays. The MPCA last conducted a water quality assessment on Lake Vermilion in 2000. Lake Vermilion is located between the towns of Tower and Cook in northeastern Minnesota. It is the seventh largest lake in Minnesota, with an area of about 39,000 acres on the southern edge of the Canadian Shield. The Lake Vermilion watershed covers approximately 488 square miles (312,000 acres) spread out over several basins. The Pike River is the dominant tributary, contributing about 40 percent of the watershed area. Lake Vermilion was sampled from May – September, primarily by Club volunteers. Samples were sent to the Minnesota Department of Health laboratory for analysis.

Distinct thermal and dissolved oxygen (DO) stratification was evident at the deeper sites; whereas the shallower sites exhibited variable or well-mixed conditions. Epilimnetic DO concentrations consistently exceeded 5 milligrams per liter (mg/L) throughout the monitoring season, a level necessary to maintain healthy cool water fisheries. Carlson’s overall Trophic State Index (TSI) on the entire lake indicates mesotrophic conditions. The individual TSI estimates for phosphorus, chlorophyll-a, and Secchi transparency align very well on a lake-wide basis. For Pike Bay, these measures were not in synch. Due to the naturally tannin- stained water, Secchi transparency and chlorophyll-a were lower than is expected at its given phosphorus concentration. In general, phosphorus is slightly lower and Secchi is higher in the West basin as compared to the East. The near record high water levels in the first half of the monitoring season did not appear to have a consistent affect across Lake Vermilion. The relatively stable phosphorus concentrations in Pike and Big Bays in 2008 may be the combined result of a steady influx of phosphorus from the Pike River, as well as wind resuspension of fine particles (e.g. clays) from shallow water sediments (which would include all of Pike Bay) throughout the summer. As lake in-flows and levels dropped by late summer, internal recycling and wind resuspension may become even more important in serving to maintain phosphorus concentrations in the shallow windswept bays. Sulfate concentrations in Lake Vermilion were relatively high in 2008 as compared to other lakes in the Northern Lakes and Forests ecoregion. The lake-wide average (10.6 mg/L) slightly exceeded the water quality standard of 10 mg/L. Concentrations were highest in Big Bay, and were lower and below the standard in the western arm of the lake. Further monitoring may be needed to fully discern the source(s) of excess sulfate and cycling of sulfate within the lake; however it seems likely that the Sandy River (a tributary to the Pike River) is an important source.

Of the eight sites sampled in 2008, three were also sampled in the MPCA’s 2000 study – Pike, Big, and Wakemup bays. Based on this comparison there was no significant difference in phosphorus, chlorophyll, or Secchi transparency on a lake-wide basis. These data suggest that water quality in Lake Vermilion has not changed significantly from 2000 to 2008 – though algal response may vary somewhat between years.

The MINLEAP model was run individually for Pike Bay and the whole lake, as was also done for the 2000 assessment report. Conclusions were very similar compared to 2000, since water quality conditions and model inputs did not significantly change between those years. The BATHTUB model provides a further basis for estimating water and nutrient budgets for the Lake Vermilion watershed using a combination of runoff, phosphorus export coefficients based on land use in the watershed, and data from similar systems in the Northern Lakes and Forests ecoregion. For this effort, we divided the lake into two distinct basins: Pike Bay and the main-basin, versus four basins in our 2000 model run. This was done to simplify inputs, since water quality did not significantly vary among the main basin sites and we lacked actual monitoring data for inflows to the various sub-basins. As has been previously discussed, Pike Bay has unique hydrology, morphology, and water quality and warrants separation from the rest of the lake. To make the 2000 and 2008 model runs as comparable as possible, model inputs were not changed unless new information and data became available to increase the model’s accuracy. In general, there is good agreement between observed and predicted chlorophyll-a and Secchi values for each basin. This suggests Lake Vermilion is generating the amount of algae we would expect based on measured phosphorus and standard regression equations. Pike Bay represents about 1.5 % of the volume of Lake Vermilion but receives runoff from about 40 percent of the watershed via the Pike River and East and West Two Rivers. These three rivers account for the vast majority of the external

Lake Vermilion CLMP+ Water Quality Report • March 2009 5 Minnesota Pollution Control Agency phosphorus loading to Pike Bay and about 60-65 percent of the total phosphorus loading (external plus internal). In comparison, on-site septic systems and the Tower wastewater ponds discharge contributed on the order of five percent of the phosphorus loading. According to data from St. Louis County, there are approximately 2,950 residences on Lake Vermilion - a 21% increase since 2000. It is very likely that this increase in development (and phosphors load) has been offset partially by the County’s septic system point of sale ordinance. When the internal loading estimates are removed from the phosphorus budget, the total phosphorus loads are very similar from 2000 to 2008- about 12,500 kilograms. Of the source-categories we have noted, some might be considered controllable (subject to management) while others are not. Sources which would generally be considered not controllable would include: atmospheric deposition of phosphorus on the lake, background runoff from forest and wetland areas (typical of this landscape), and diffusive sources (mixing within the lake). Those sources that can be viewed as controllable would include: a portion of the septic system effluent that leaches to the lake, wastewater discharges, a portion of the urban runoff (stormwater) that drains to the lake from driveways, parking lots, rooftops, lawns and other surfaces which contribute runoff and phosphorus to the lake. While septic systems appeared to be a small contributor (on a lake-wide basis) it may be among the most “controllable” portion of the phosphorus loading to the lake considering that atmospheric and natural background loads cannot be reduced.

In summary, the similarity in measured (i.e. monitored) and modeled water quality in 2000 and 2008 and the lack of significant trends in the long term datasets provide multiple lines of evidence that Lake Vermilion’s water quality is relatively stable, generally within typical ranges for area lakes and meets Minnesota’s Northern Lakes and Forest ecoregion lake nutrient standards. It is important for the SCLV and area management agencies to continue their excellent work in protecting the Lake Vermilion watershed. Potential threats to the lake are numerous; such as exotic species invasions, increasing lakeshore development, and global climate change.

Lake Vermilion CLMP+ Water Quality Report • March 2009 6 Minnesota Pollution Control Agency

Introduction

Minnesota’s Citizen Lake Monitoring Program (CLMP) is the largest and oldest volunteer lake monitoring program in the country. Volunteers in the CLMP currently use a Secchi disk to measure the clarity on hundreds of Minnesota’s lakes. The expanded program, including the collection of water chemistry samples for analysis along with Secchi transparency collection, was conducted in 2008 on Lake Vermilion. The study was conducted cooperatively with volunteers from the Sportsmen’s Club of Lake Vermilion (SCLV) and staff from the Minnesota Pollution Control Agency (MPCA). A total of 8 sites were selected for monitoring in 2008 (Table 1, Figure 1), some of which were established Minnesota Department of Natural Resources (DNR) Large Lake monitoring sites or sites sampled previously by the MPCA during their 2000 Lake Assessment (Anderson and Heiskary, 2001).

Table 1. 2008 Lake Vermilion Water Quality Monitoring Stations Lake Vermilion Site Site Basin Name Depth at Notes Name Number Site (feet) Pike Bay 116 Pike Bay 7 Established MPCA station Big Bay 130 East 76 DNR, MPCA station Armstrong Bay 134 East 25 New in 2008 Frazer Bay 132 East 40 DNR Station Trout Lake Portage 113 East 20 DNR Station Niles Bay 102 West 55 DNR Station Wakemup Bay 131 West 55 DNR, MPCA station Head of the Lakes Bay 133 West 50 New in 2008

Figure 1. Map of 2008 Lake Vermilion Monitoring Sites, Courtesy of Mel Hintz, SCLV

Lake Vermilion CLMP+ Water Quality Report • March 2009 7 Minnesota Pollution Control Agency

All equipment and analytical costs for the samples were provided for and paid by the MPCA. Volunteers on these lakes collected water chemistry samples and temperature profiles twice per month. After sampling, the volunteers dropped off their samples at a predetermined location within their county. Thanks to the staff at the DNR office in Tower and the Superior National Forest office in Cook in coordinating shipping of samples. Special thanks to the volunteers who helped make this project a success:

Central Team: Jeff Lovgren (Leader), Darryl L. Johnson, Walt Moe, Marcie Moe, Kathy Lovgren, Dick Johnson, Mardy Jackson, Don Johnson, Barbara Dobson

East Team: Mel Hintz (Leader), Bob Wilson, Ellen Hintz, Tom Mesojedic, Steve Lotz

West Team: Rick Borken (Leader), Ed Zottola, Chuck Richards, Bob Kocks, Steve Herr, Steve Towle, Joanne Bergman, Ed Borowiec, Jim Mueller, Judy Moline, Larry Lange, Gary and Alberta Whitenack, Dave and Lucie Schwartz.

MPCA Staff: Don Carlson, Jenny Magyar, Stacia Schacht, Johanna Schussler, Pam Anderson, Brittany Story, Jesse Anderson

Background Information

Lake Assessment Overview

The MPCA core lake monitoring programs include the CLMP and the Lake Assessment Program (LAP). In addition to these programs, the MPCA annually monitors numerous lakes to provide baseline water quality data, provide data for potential LAP, and characterize lake conditions in different regions of the state. MPCA also examines year-to-year variability in ecoregion reference lakes and provides additional trophic status data for lakes exhibiting trends in Secchi transparency.

Lake Trophic status

Total phosphorus (TP), chlorophyll-a (Chl-a) and Secchi transparency are closely interrelated and are collectively used to characterize the “trophic status” of lakes. One means to evaluate the trophic status of a lake and to interpret the relationship between TP, Chl-a and Secchi transparency is Carlson's Trophic State Index (TSI) (Carlson 1977). This index was developed from the interrelationships of summer Secchi transparency and the concentrations of surface water Chl-a and TP. TSI values are calculated as follows:

TP TSI (TSIP) = 14.42 1n (TP) + 4.15 Chl-a TSI (TSIC) = 9.91 1n (Chl-a) + 30.6 Secchi disk TSI (TSIS) = 60 - 14.41 1n (SD) TP and Chl-a are in micrograms per liter (μg/L) and Secchi transparency is in meters and TSI values range from 0 (ultra-oligotrophic) to 100 (hypereutrophic).

In this index, each increase of 10 units represents a doubling of algal biomass. The following is a list of TSI ranges and the typical observations associated with them (Figure 2). This index is based on the interrelationship of the three variables and allows for the prediction of any variable.

Lake Vermilion CLMP+ Water Quality Report • March 2009 8 Minnesota Pollution Control Agency

Figure 2. Carlson’s Trophic State Index, R.E. Carlson 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 TRANSPARENCY (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.

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Legend County Ecoregion Driftless Area Red River Valley North Central Hardwood Forests Northern Glaciated Plains Northern Lakes and Forests Northern Minnesota Wetlands

Western Corn Belt Plains

Figure 3. Minnesota’s Ecoregions. Lake Vermilion is located in the Northern Lakes and Forests (NLF) ecoregion.

The state of Minnesota is divided into seven ecoregions (Figure 3), based on soils, landform, potential natural vegetation, and land use. Lake Vermilion is located within the Northern Lakes and Forest (NLF) ecoregion. Comparing a lake’s water quality to that of reference lakes in the same ecoregion provided one basis for characterizing the condition of the lake.

Lake depth can have a significant influence on lake processes and water quality (Figure 4). 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. These lakes full-mix or turn-over twice per year; typically in spring and fall. 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, may stratify intermittently during calm periods. In Lake Vermilion, shallow Pike Bay is polymictic, whereas larger, deeper bays like Big Bay and Head of the Lakes are dimictic. Measurement of temperature throughout the water column (surface to bottom) at selected intervals (e.g. every meter) can be used to determine whether the lake is well-mixed or stratified. It can also identify the depth of the thermocline (zone of maximum change in temperature over the depth interval). In general, the upper, well- mixed layer (epilimnion) is warm and has high oxygen concentrations. In contrast, the lower layer (hypolimnion) is much cooler and often has little or no oxygen. Most of the fish in the lake will be found in the epilimnion or near the thermocline. The combined effect of depth and stratification can influence overall water quality.

Lake Vermilion CLMP+ Water Quality Report • March 2009 10 Minnesota Pollution Control Agency

Figure 4. Mixing Types and Lake Layers for Shallow and Deep Lakes

Polymictic Lake Shallow, No Layers, Wind Mixes Continuously Spring, Summer &

Dimictic Lake Wind Deep, Form Layers, Epilimnion Mixes Few Times Metalimnion Summer

Hypolimnion

Wind Dimictic Lake Deep, Form Layers, Mixes Few Times Spring/Fall

Lake Vermilion CLMP+ Water Quality Report • March 2009 11 Minnesota Pollution Control Agency

In deeper lakes that are typically well-mixed in April and May, following ice-out and wind-mixing, we often see elevated TP and Chl-a. As the lakes begin to stratify a reduction in TP and Chl-a is often noted by June. If the lake remains stratified over the summer we often observe stable or slightly declining TP over the summer, absent any major precipitation and runoff events. This decline is a reflection of algal uptake of P combined with natural sedimentation processes. While internal recycling of P will often occur it is typically limited to the hypolimnion and does not tend to mix with the surface waters until fall overturn. Chl-a concentrations often increase over the summer as the waters warm and algal dominance shifts from diatoms to blue-greens. As algal (i.e. Chl-a) concentrations increase, Secchi will decrease.

In shallow lakes a somewhat different Figure 5. Monthly Mean TP, Chl-a and Secchi. Based on 30 shallow lakes sampled from West-Central MN in 2003. pattern is noted. If TP and Chl-a are measured in April, it is not uncommon to 200 0 see high concentrations followed by a 180 -2 decline in May. May and sometimes early 160

June Chl-a concentrations may be kept 140 relatively low as a result of zooplankton -4 grazing and perhaps rooted plant growth; 120 100 -6

however, as the summer progresses we ppb often see a marked increase in both TP and 80 Meters -8 Chl-a in shallow lakes (Figure 5). In these 60 shallow, well-mixed lakes internal 40 recycling of P (absent significant summer -10 runoff events) is often a primary cause of 20 the seasonal increase in TP. Various 0 -12 factors can contribute to the recycling and May June July August Sept. likely include things such as: die-off of TP Chl-a Secchi curly-leaf pondweed, frequent wind mixing, increased temperatures and internal P-release along with various other factors (Heiskary and Wilson, 2005). As a result, dramatic increases in Chl-a concentrations are noted over the summer and these blooms are often dominated by blue-green algae, which accumulate near the surface. In turn, Secchi tends to decline over the summer in response to increased algae concentrations.

Awareness of these differing seasonal patterns will aid in the assessment of Minnesota lakes; in turn this should aid in the development of the Total Maximum Daily Load, or impaired waters, studies, and may be of particular use in developing an implementation plan and projecting improvements that may result from its implementation

Study Area Overview, Basin Hydrology, and 2008 Climate Summary

Lake Vermilion is located between the towns of Tower and Cook in northeastern Minnesota (Figure 1). It is the seventh largest lake in Minnesota, with an area of about 39,000 acres. The lake is on the southern edge of the Canadian Shield, and was formed during the last glaciation (~ 10,000 years ago). The thin soils and surficial bedrock common throughout the lake’s watershed and much of the NLF ecoregion (Figure 3) are a result of the retreating glaciers. The DNR has divided Lake Vermilion into 3 distinct areas- Pike Bay, and an Eastern and Western Portion of the main lake basin. The Pike River, which flows north off the Laurentian Divide, is the Lake’s main tributary and flows into the shallow Pike Bay. From there water moves north into the large Eastern Basin, meeting up with the Western Portion of Lake Vermilion at the outlet of Oak Narrows. Water then flows North through Niles Bay towards the Lake’s outlet at the Vermilion River. Water then flows downstream to the large lakes of Voyageur’s National Park. In general, the western portion of Lake Vermilion is less developed than the Eastern Portion- which contains the cities of Tower and Soudan, and recreational development centered around the Bois Forte Band of Chippewa’s Fortune Bay Resort.

Lake Vermilion has a diverse and heterogeneous morphometry (Figure 1). There are numerous bays among the three distinct basins. The mean depth of the lake is approximately 20 feet, and the maximum depth is 76

Lake Vermilion CLMP+ Water Quality Report • March 2009 12 Minnesota Pollution Control Agency feet. For the purposes of our study and this report, we have selected 8 monitoring locations, spread out among the three main basins (Table 1). Assistance from SCLV allowed us to sample additional sites that weren’t visited in 2000, and therefore improved our overall water quality assessment. Mean depths were estimated for each basin by inspection of the maps and best professional judgment. Future efforts to improve on the modeling herein should include planimetry of the actual maps to allow for more accurate definition of mean depth. Watershed areas were estimated based on USGS Web-based maps of the subwatersheds of Lake Vermillion. A brief summary of each sampled Bay follows:

• Pike Bay is the southern most bay and is located at the mouth of the Pike River. It is very shallow and bog stained with a mean depth of about 5 feet (1.5 m) and has a surface area of about 2,149 acres (3.35 mi2). This bay accounts for about one percent of the volume of the lake but receives runoff from 40% of the lake’s watershed via the Pike, East Two and West Two Rivers. Therefore, it has a very short residence time, estimated at about 30 days. The city of Tower is located in this watershed and the municipal Wastewater Treatment Facility (WWTF) discharges to the Bay.

• Big Bay is the largest of the bays at approximately 17,000 acres, accounts for about 40 percent the lake’s surface area, and is immediately to the north of Pike Bay. It is much deeper than Pike Bay with a maximum depth of 76 ft (23 m) and an approximate mean depth of 19 ft (5.8 m). It also has an extremely large fetch (distance over which the wind can blow unimpeded by land) of about 5 - 6 miles (8 – 9.6 km) which contributes to the well-mixed conditions throughout most of the open water season. It has a relatively small immediate watershed relative to its size.

• Armstrong Bay is located at the extreme eastern end of Lake Vermilion. This area of the lake has a mean depth of about 20 feet. It is currently undeveloped, and is near the site of potential future development – either a new state park, or large residential development

• Frazer Bay is located just south of Oak Narrows, the Lake’s East / West boundary. This area of the lake is slightly deeper than Big Bay, with an average depth of about 30 feet.

• Trout Lake Portage Bay is located at the outlet of Trout Lake, northeast of Frazer Bay, and is a shallow, sheltered part of the lake with an average depth about 15 feet. This is a relatively undeveloped portion of the lake; parts of the north side of the bay are within the Boundary Waters Canoe Area Wilderness.

• Niles Bay is a large deep bay near the lake’s outlet. It has a large fetch of about 3 miles and an average depth of 40 feet. Water from the Eastern portion of the lake empties into the southeast corner of Niles Bay

• Wakemup Bay is the main bay in the northwest part of the lake. This bay is moderately deep with a maximum depth of 57 ft (17.3 m) and mean depth of about 23 ft. (7 m). This portion of the lake has a relatively small watershed. Water from this bay and Big Bay flow northward to Wolf Bay, which represents the outlet of the lake and the beginning of the Vermilion River.

• Head of the Lakes Bay is at extreme western end of the lake, and has a very small drainage area. It is fairly deep with an average depth of about 35 feet.

Because Pike Bay is hydrologically different from the rest of Lake Vermilion, we separated it out when describing the lake’s overall morphology (size and shape). Pike Bay covers about 5% of the lake area, and has just 1.6 % of the lake’s volume. Littoral areas, defined as those areas less that 15 feet in depth, cover all of Pike Bay versus about 35% of the remainder of the lake (Table 2).

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Table 2. Lake Vermilion Morphology

Lake Littoral area Total Watershed: Max. Average Lake Lake Lake ID Basin Watershed Lake Ratio Depth Depth2 Volume Name Area 1 2 Acres Acres % Acres Ft. Ft. Acre-Ft. Vermilion- 69-0378 38,884 15,006 39 312,318 8:1 76 777,680 Entire ~ 20 Lake

Vermilion- 69-0378-03 2,149 2,149 100 141,668 66:1 8 ~ 6 12,894 Pike Bay Vermilion- 69-0378 36,735 12,857 35 170,650 4.6 : 1 76 ~ 21 764,786 Main Basin

1. Includes the lake area 2. Approximate

The Lake Vermilion watershed (Figure 6) covers approximately 488 square miles (312,000 acres) spread out over several basins (Table 3). The Pike River is the dominant tributary, contributing about 38 percent of the watershed area. Next is the immediate lake drainage – defined as the lake area itself, islands, and near-shore direct runoff. The Trout Lake basin contributes about 10 % of the watershed, followed by the East and West Two Rivers (6.7 %), Armstrong River (3 %) then numerous small streams and creeks (13% in total).

Table 3. Lake Vermilion’s Contributing Watershed Areas. Data from U.S. Geological Survey (http://gisdmnspl.cr.usgs.gov/watershed/start_page.htm )

Basin Name Watershed Area (acres) Percent of Total Pike River Watershed 118,400 37.9 Immediate Lake Drainage1 90,240 28.8 Trout Lake Watershed 32,512 10.4 East and West Two Rivers 21,056 6.7 Watersheds Bear, Black, Mud, Sunset Creeks 20,032 6.4 Armstrong River Watershed 9,344 3.0 All Other Small Drainages 20,672 6.6 1 Including Lake Area

Lake Vermilion CLMP+ Water Quality Report • March 2009 14 Minnesota Pollution Control Agency

Figure 6. Lake Vermilion Watershed

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Land use in the Lake Vermilion watershed is dominated by forest, open water, and wetlands (Table 4, Figure 7). Land use percentages fall within the range of other lakes in the NLF ecoregion. On the watershed scale, urban and developed land comprise a small portion, between 1 - 2 percent; however, lakeshore development has increased around the lake since the MPCA’s 2000 study. In 2000, the St. Louis County Planning Department estimated that there were approximately 2,330 residences (based on a count of “fire numbers”) on the lake; in 2008, this figure was 2,957 - an increase of 21 percent. The total number of private parcels on the lake in 2008 was 4,487 with 2,957 having a building value. Since August 2001, a total of 254 septic systems have been upgraded in the townships around Lake Vermilion, with most of these on the lakeshore (Rich Hyrkas, St. Louis County Environmental Services Department – personal communication, January, 2009).

Table 4. Lake Vermilion watershed land use data as compared to NLF ecoregion reference lake interquartile ranges. Vermilion based on 2001 GIS imagery. Land Use / Land Cover Lake Vermilion NLF Ecoregion Land Use % Forest 74.5 54 – 81 Open Water 1 17.7 Wetlands 4.7 14- 31 Pasture & grasslands 1.1 0 – 6 Cultivated 0.1 < 1 Barren Land & Bedrock 0.6 Urban & Developed 1.2 0 – 7

1. Including lake areas; figure is primarily Lake Vermilion, Trout, and Eagles Nest Lakes

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Figure 7. Lake Vermilion Watershed Land Cover

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Precipitation and Lake Levels Total precipitation in water year 2008 (which integrates the monitoring season: October 2007 to September 2008) was slightly higher than average; however, the spring was very wet, up to 250 % above normal in vicinity of Lake Vermilion (Figure 8.). This led to near-record high water levels in spring 2008. Water levels in the spring 2008 were the highest recorded by the DNR since monitoring began in 1951. They peaked on 5/17/08 at 1359.32 feet (Figure 9). For about the first third of the 2008 monitoring season, lake levels exceeded the DNR’s Ordinary High Water Level (OHWL), which is 1358.35 feet. For most of the recent 10 years, the OHWL was rarely exceeded; however, lake levels have generally been above the long-term mean lake level during this period (Figure 10). The OHWL is defined in state statute 103G.005 as “ an elevation delineating the highest water level that has been maintained for a sufficient period of time to leave evidence upon the landscape, commonly the point where the natural vegetation changes from predominantly aquatic to predominantly terrestrial”. The highest known elevation on Lake Vermilion occurred June 6, 1913 at 1359.94 feet (http://www.dnr.state.mn.us/lakefind/showlevel.html?id=69037800 ).

Figure 8. Spring 2008 and 2008 Water Year Precipitation Totals.

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Figure 9. 2008 Lake Vermilion Lake Levels (DNR Waters). Ordinary High Water Level of 1358.35 feet is noted as the red line.

1360

1359.5

1359

1358.5

1358

1357.5

Elevation (feet) 1357

1356.5

1356

6/9/08 7/7/08 8/4/08 9/1/08 5/12/08 5/26/08 6/23/08 7/21/08 8/18/08 9/15/08 9/29/08

10/13/08 10/27/08 11/10/08 Date

Elev. (ft) Sample Collected

Figure 10. 1994 to 2008 Lake Vermilion Water Levels. Red line denotes OHWL and blue line denotes long- term average. Data courtesy of DNR Waters.

Lake Vermilion Lake Levels 1994- 2008

1359.5

1359.0

1358.5

1358.0

(ft) Level 1357.5

1357.0

1356.5

1356.0 5/6/94 5/6/95 5/5/96 5/5/97 5/5/98 5/5/99 5/4/00 5/4/01 5/4/02 5/4/03 5/3/04 5/3/05 5/3/06 5/3/07 5/2/08 Date

Lake Vermilion CLMP+ Water Quality Report • March 2009 19 Minnesota Pollution Control Agency

Fisheries Summary – [Provided by Duane Williams, Lake Vermilion Large Lake Specialist, MN DNR]

Lake Vermilion is part of the statewide Large Lake Program, an intensive fisheries management program on the 10 largest lakes in Minnesota. The Large Lake Program includes annual population assessments, annual water quality monitoring, and regularly scheduled creel surveys. A variety of sampling gear is used during population assessments to collect the various fish species and life stages. These gear types include gill nets, trap nets, beach seines, and an electrofishing boat. Sampling for each gear type is conducted at the same time and place each year in order to determine population trends for the major species. Data are also collected on length, weight, age, and growth for each of the major species.

The walleye gill net catch in 2008 was 12.9 fish/net, slightly below the historical average and the lowest walleye catch on Lake Vermilion in several years. The relatively low walleye catch was due primarily to poor reproduction in 2004 and 2005. Gill netted walleye had a mean length of 13.2 inches, slightly above the historical average. The gill net catch of 12-15 inch walleye was well below average for those size classes, reflecting poor reproduction in 2004 and 2005. The catch of small walleye was above average, indicating the presence of strong younger year classes in the population. The gill net catch of walleye over 17 inches was also above average, especially on West Vermilion. These larger walleye are from strong year classes produced in 2002 and 2003. The walleye gill net catch was dominated by age 1 fish (2007 year class) and age 2 fish (2006 year class), which comprised 20.9% and 35.5% of the catch, respectively. Both the 2006 and 2007 year classes appear to be moderately strong. Strong year classes of walleye were also produced in 2002 and 2003, while poor year classes were produced in 2004 and 2005. A special walleye regulation went into effect on Lake Vermilion in 2006; a 17-26 inch protected slot with one fish allowed over 26 inches, and a four fish bag limit. A more restrictive regulation was adopted because of increased fishing pressure and walleye harvest. The regulation will help keep harvest at a safe level while allowing anglers to keep eating sized walleye.

The gill net catch of northern pike was 0.8 fish/net, slightly below the historical average. Gill net catches of northern pike have historically been fairly stable at a relatively low level. The mean length of northern pike sampled by gill nets was 26.7 inches, slightly above the historical average, although the sample size was only 15 fish. Reproduction of northern pike is usually fairly consistent from year to year, although it appears a relatively poor year class was produced in 2003. A special regulation for northern pike went into effect on Lake Vermilion in 2003; a 24-36 inch protected slot, with one fish allowed over 36 inches. This regulation is part of a statewide initiative to improve the size structure of pike populations in a number of lakes across the state.

The gill net catch of yellow perch was 13.9 fish/net, the lowest perch catch since large lake sampling began in 1984. The low perch catch was due primarily to poor reproduction in 2004. Gillnetted perch had a mean length of 7.7 inches, well above the historical average. The large average size reflects low numbers of small perch in the gill net catch. The perch catch was dominated by age 3 fish (2005 year class), which comprised 36.6% of the catch. Strong year classes of perch were produced in 2001 and 2002, while a poor year class was produced in 2004.

The trap net catch of bluegill was 44.5 fish/net, well above the historical average. The bluegill catch was much higher on West Vermilion than East Vermilion, reflecting higher bluegill abundance in that lake basin. Trap netted bluegill had a mean length of 5.7 inches, well below the historical average. The small average size was due to high numbers of small fish in the catch from strong 2005 and 2006 year classes. The bluegill trap net catch was dominated by age 3 fish (2005 year class), which comprised 37.4% of the catch. Strong year classes of bluegill were produced in 2002, 2005, and 2006, while a poor year class was produced in 2004.

The black crappie trap net catch was 1.4 fish/net, slightly below the historical average. Crappie numbers have historically been relatively low on Lake Vermilion, although some areas of West Vermilion have higher numbers of fish. Trapnetted crappie had a mean length of 8.0 inches, slightly below the historical average. Above average numbers of small crappie were sampled from a strong year class produced in 2006. The catch of 8-9 inch crappie was also above average, reflecting the presence of a strong 2005 year class. The crappie catch was dominated by age 3 fish (2005 year class), which comprised 67.5% of the catch. Strong year classes of crappie were produced in 2001, 2005, and 2006, while a poor year class was produced in 2004.

Lake Vermilion CLMP+ Water Quality Report • March 2009 20 Minnesota Pollution Control Agency

An electrofishing boat is used as the standard sampling gear for smallmouth bass because they are not often caught in standard assessment nets. The smallmouth bass electrofishing catch in 2008 was 54.3 fish/hour, well above the historical average and the second consecutive year of unusually high bass catches. Smallmouth bass sampled by electrofishing had a mean length of 9.9 inches, slightly above the historical average. High numbers of 12-13 inch bass were sampled from strong year classes produced in 2002 and 2003. The bass catch was dominated by age 2 fish (2006 year class) and age 3 fish (2005 year class), which together comprised 56.5% of the total catch. It appears both the 2005 and 2006 year classes will be much stronger than average. Moderately strong year classes of smallmouth bass were also produced in 2001, 2002, and 2003, while a poor year class was produced in 2004.

An electrofishing boat is used to sample young-of-the-year walleye in the fall to monitor reproductive success for the year. The fall electrofishing catch of young-of-the-year walleye was 130.3 fish/hour, slightly above the historical average. The mean length of young-of-the-year walleye sampled by electrofishing was 5.1 inches, slightly below the historical average. Growth of young-of-the-year walleye has proven to be a useful indicator of eventual year class strength. Past sampling has shown that large, fast growing young-of-the-year walleye generally produce strong year classes, while small slow growing fish produce poor year classes. Taken together, the 2008 electrofishing catch and growth rate indicate the 2008 year class will be slightly weaker than average.

Muskie population assessments have been done once every four years on Lake Vermilion, although future assessments will be done once every six years. East Vermilion and West Vermilion are done in different years due to the large size of the lake. Trap net catches of muskie have been gradually increasing since the first assessments were done in 1993 and 1994. The number of large fish has also been increasing. Over 15% of the muskie sampled in 2005 and 2006 were over 50 inches long. The largest muskie sampled during the 2005- 2006 assessments was 54.7 inches long. The next assessments are scheduled for 2010 and 2011.

Lake Vermilion CLMP+ Water Quality Report • March 2009 21 Minnesota Pollution Control Agency

Methods

This report includes data from 2008 as well as previously collected data available in STORET, U.S. Environmental Protection Agency’s (EPA) national water quality data bank. The following discussion assumes familiarity with basic limnology terms as used in a “Guide to Lake Protection and Management” and as commonly used in LAP reports. A glossary of terms is included in the appendix and can also be accessed at http://www.pca.state.mn.us/water/lakeacro.html.

The Lake Vermilion sites were sampled once in May, and twice per month June – September. Most of the monitoring was conducted by SCLV volunteers. MPCA staff sampled the lake in May, late July and late September (due to high winds on the late September sampling date, only 2 of the 8 sites could be sampled). Lake surface samples were collected with an integrated sampler, constructed from a PVC tube 6.6 feet (2 meters) in length with an inside diameter of 1.24 inches (3.2 centimeters). Lake-bottom samples were collected 1 meter off the bottom of the lake by MPCA staff using a Kemmerer sampler. Averages were calculated using May – September data. Sampling procedures were employed as described in the MPCA Quality Control Manual and Citizen Lake-Monitoring Program “Plus” Manual. Laboratory analyses were performed at the Minnesota Department of Health using EPA-approved methods. Surface samples from volunteers were analyzed for: TP, Chl-a, pheophytin, and sulfate. Secchi disk transparency and user perception information was recorded at all sites. Volunteers also collected dissolved oxygen (DO) and temperature profiles for each site using a HACH model – HQ30D luminescent DO and temperature meter. Algae samples were collected from the Chl-a sample bottles, preserved with Lugol’s solution and analyzed by MPCA staff: Dr. Howard Markus and Matt Lindon1.

MPCA staff collected surface samples and bottom samples for each site on three occasions. These data serve to augment the volunteer collection and provide an opportunity for comparison of results. MPCA collected surface samples were analyzed for the following parameters: TP, Chl-a, pheophytin, total Kjeldahl nitrogen (TKN), nitrate and nitrite (NO2+NO3), total suspended solids (TSS), suspended volatile solids (SVS), total chloride, alkalinity and color. Conductivity, pH, and DO and temperature profiles were collected using a Hydrolab multi-probe unit. Lake-bottom samples were analyzed for TP. Secchi disk transparency and user perception information was recorded for each site. Qualitative analysis of zooplankton collected using a Wisconsin net was also recorded for each site. During the MPCA’s September sampling, a wider Wisconsin net was used, to specifically look for the exotic zooplankton spiny water flea. It was not found in the sites we sampled.

Quality Assurance/Quality Control (QA/QC) samples were taken routinely throughout the sampling season. A field duplicate is a second sample collected in the same manner and location right after an initial sample. Field duplicates are used to assess the sampler and lab precision (i.e. reproducibility).

Laboratory and Field Analysis

All water quality samples, with the exception of phytoplankton, were analyzed the Minnesota Department of Health (MDH) lab in St. Paul. Method numbers and associated quality assurance information is noted for several of the parameters (Table 5).

1 At the time of this report, algal samples were not yet analyzed. The report will be updated online as the data becomes available.

Lake Vermilion CLMP+ Water Quality Report • March 2009 22 Minnesota Pollution Control Agency

Table 5. MDH laboratory methods and precision estimates

Parameter Reporting Limit & Method Precision: 1 Difference as % Units number mean difference of observed Total Phosphorus 3.0 µg/L EPA365.1 4.8 µg/L 2.7 % Total Kjeldahl N 0.1 mg/L EPA351.2 0.05 mg/L 2.8 %

NO2 + NO3 0.05 mg/L EPA353.2 -- -- Total Suspended Solids 1.0 mg/L SM2540D 2.8 mg/L 9.6 % Total Suspended Volatile Solids 1.0 mg/L SM2540E -- -- Alkalinity as CaCO3 10 mg/L SM 2320 B -- -- Chloride 1.0 mg/L EPA 325.2 -- -- Color 5 Pt-CU EPA 110.2 -- -- Chlorophyll-a SM10200H 1.7 µg/L 7.4 % Pheophytin SM10200H -- -- 1 Average of individual means of 10 duplicates and expressed as a % of measured concentrations

The Minnesota Lake Eutrophication Analysis Procedure (MINLEAP) computer model was used to predict the TP concentration, Chl-a concentration, and Secchi disk transparency of the lakes based on lake area, lake depth, and the total area each lake watershed. Pike Bay was modeled separately from the main basin of the lake. Additional information about this model can be found in the modeling section of this report or a complete explanation of this model may be found in Wilson and Walker (1989).

The BATHTUB model (Walker, 2004) provides a further basis for estimating water and nutrient budgets for Lake Vermillion using a combination of runoff and P export coefficients based on land use in the watershed and data from similar systems in this ecoregion. This model allows for the “routing” of water and nutrient loads between the basins. In this fashion improved estimates of nutrient and water exchange can be obtained and improved estimates of in-lake condition should be possible. Further details on the BATHTUB model run will be discussed later in the report.

photo by Marshall Helmberger

Lake Vermilion CLMP+ Water Quality Report • March 2009 23 Minnesota Pollution Control Agency

Results and Discussion A series of graphs are presented for each site on Lake Vermilion including: TP, Chl-a, Secchi disk transparency, temperature and DO profiles. All water quality data for each site are available in the Appendix.

2008 Dissolved Oxygen and Temperature Profiles

The following pages summarize DO and temperature profiles and pertinent observations for each monitoring site (Figures 11-18) In 2008, the ice-out date was May 12, so our data from May 16 illustrate very cold temperatures, around 5 degrees Celsius. As expected, all sites reached their annual maximum surface temperatures in August, and temperatures declined thereafter. Distinct thermal and DO stratification was evident at the deeper sites, whereas the shallower sites exhibited variable or well-mixed conditions. Epilimnetic DO concentrations consistently exceeded 5 mg/L throughout the monitoring season, a level necessary to maintain healthy cool water fisheries.

Figure 11. Pike Bay Temperature and DO Profile. Shallow and thermally well-mixed from top to bottom. Warmest bay with maximum temperature of 23 C. DO remains above 5 mg/L.

Site 116

Temp (C) 5 10152025 0

5/16/2008 0.5 6/2/2008 6/23/2008 1 7/7/2008 7/22/2008 8/5/2008

Depth (M) Depth 1.5 8/18/2008 9/3/2008 2 9/30/2008

2.5

Site 116

DO (mg/L) 567891011 0

5/16/2008 0.5 6/2/2008 6/23/2008 1 7/7/2008 7/22/2008 8/5/2008

Depth (M) Depth 1.5 8/18/2008 9/3/2008 2 9/30/2008

2.5

Lake Vermilion CLMP+ Water Quality Report • March 2009 24 Minnesota Pollution Control Agency

Figure 12. Big Bay Temperature and DO Profile. Thermal stratification evident from late June through early August. Mixing underway by late August. Thermocline forms between 8-12 m. DO falls below 5 mg/L below thermocline. High winds and cooling of water allow for fall mixing in September.

Site 130

Dissolved Oxygen (mg/L) 024681012 0

5 5/16/2008 6/2/2008

10 6/23/2008 7/7/2008 7/22/2008

Depth (M) Depth 15 8/5/2008 8/18/2008 20 9/3/2008

site 130

Temp (C) 0 5 10 15 20 25 0

5 5/16/2008 6/2/2008

10 6/23/2008 7/7/2008 7/22/2008

Depth (M) Depth 15 8/5/2008 8/18/2008 20 9/3/2008

Lake Vermilion CLMP+ Water Quality Report • March 2009 25 Minnesota Pollution Control Agency

Figure 13. Armstrong Bay Temperature and DO Profile. Very minimal thermal stratification with no distinct thermocline. DO declines near bottom but generally remains above 5 mg/L.

Site 134

Temp (C) 5 10152025 0

1 5/16/2008 2 6/2/2008 3 6/23/2008 7/7/2008 4 7/22/2008

Depth (M) Depth 5 8/5/2008 8/18/2008 6 9/3/2008 7

Site 134

DO (mg/L) 024681012 0

1 5/16/2008 2 6/2/2008 3 6/23/2008 7/7/2008 4 7/22/2008

Depth (M) Depth 5 8/5/2008 8/18/2008 6 9/3/2008 7

Lake Vermilion CLMP+ Water Quality Report • March 2009 26 Minnesota Pollution Control Agency

Figure 14. Frazer Bay Temperature and DO Profile. Thermal stratification initiated in late June and is maintained until late September. Thermocline forms between 5-8 m. DO falls below 5 mg/L below thermocline and falls to <1.0 mg/L above the sediments.

site 132

Temp (C) 0 5 10 15 20 25 0

2 5/15/2008 6/2/2008 4 6/23/2008 6 7/7/2008 7/21/2008 8 8/4/2008 Depth (M) Depth 8/18/2008 10 9/3/2008 9/29/2008 12

Site 132

DO (mg/L) 02468101214 0

2 5/15/2008 6/2/2008 4 6/23/2008 6 7/7/2008 7/21/2008 8 8/4/2008 Depth (M) Depth 8/18/2008 10 9/3/2008 12 9/29/2008

Lake Vermilion CLMP+ Water Quality Report • March 2009 27 Minnesota Pollution Control Agency

Figure 15. Trout Lake Portage Temperature and DO Profile. Slight thermal stratification from June through July. Well-mixed in August and September. Rapid decline in DO below thermocline, with values < 1.0 near sediment.

site 113

Temp (C) 5 10152025 0

1 5/16/2008 2 6/2/2008 3 6/23/2008 7/7/2008 4 7/22/2008

Depth (M) Depth 5 8/4/2008 8/18/2008 6 9/3/2008 7

site 113

DO (mg/L) 024681012 0

1 5/16/2008 2 6/2/2008

3 6/23/2008 7/7/2008 4 7/22/2008

Depth (M) Depth 5 8/4/2008 6 8/18/2008 9/3/2008 7

Lake Vermilion CLMP+ Water Quality Report • March 2009 28 Minnesota Pollution Control Agency

Figure 16. Niles Bay Temperature and DO Profile. Thermal stratification from June through August. DO levels fall below 5 mg/L below the thermocline and <1.0 mg/L near the sediments.

Site 102

Temp (C) 510152025 0

6/2/2008 4 6/23/2008 6 7/7/2008 7/21/2008 8 8/4/2008 Depth (M) Depth 8/18/2008 10 9/8/2008

site 102

DO (mg/L) 024681012 0

6/2/2008 4 6/23/2008 6 7/7/2008 7/21/2008 8 8/4/2008 Depth (M) Depth 8/18/2008 10 9/8/2008

Lake Vermilion CLMP+ Water Quality Report • March 2009 29 Minnesota Pollution Control Agency

Figure 17. Wakemup Bay Temperature and Oxygen Profile. Thermal stratification from June through August with fall mixing underway by early September. DO falls below 5 mg/L below the thermocline and are <1.0 mg/L near the sediments

Site 131

Temp (C) 0 5 10 15 20 25 0

2 5/15/2008 4 6/2/2008 6/24/2008 6 7/7/2008 7/21/2008 8 Depth (M) 8/4/2008 10 8/18/2008 9/8/2008 12

site 131

DO (mg/L) 02468101214 0

2 5/15/2008 4 6/2/2008 6/24/2008 6 7/7/2008 7/21/2008 8 Depth (M) Depth 8/4/2008 10 8/18/2008 9/8/2008 12

Lake Vermilion CLMP+ Water Quality Report • March 2009 30 Minnesota Pollution Control Agency

Figure 18. Head of the Lakes Bay Temperature and DO Profile. Thermal stratification from June through August with fall mixing underway in September. DO falls below 5 mg/L below thermocline and is <1.0 mg/L near sediments.

Site 133

Temp (C) 0 5 10 15 20 25 0 2 5/15/2008 4 6/2/2008 6/24/2008 6 7/7/2008 7/21/2008 8 Depth (M) Depth 8/4/2008 10 8/18/2008 9/8/2008 12

site 133

Dissolved Oxygen (mg/L) 02468101214 0

2 5/15/2008 4 6/2/2008 6/24/2008 6 7/7/2008 7/21/2008 8 Depth (m) 8/4/2008 8/18/2008 10 9/8/2008 12

Lake Vermilion CLMP+ Water Quality Report • March 2009 31 Minnesota Pollution Control Agency

2008 Water Quality Summary

Mean 2008 water quality measurements for each site and the typical range for NLF ecoregion lakes, based on the ecoregion reference lakes are presented in Table 6. Carlson TSI values for TP, Chl-a, and Secchi transparency for Pike Bay and the main basin of Lake Vermilion are presented in Figure 19. TP is highest in Pike Bay as a combined result of its shallowness and inputs from the Pike River, which is the single largest tributary to the lake. While TP is higher than concentrations found elsewhere in Vermilion, it is near the typical range for NLF ecoregion lakes (Table 6). Chl-a is lower in Pike Bay as compared to other bays on the lake and is low relative to TP (Figure 19). This is likely due to light limitation from the bog-stained water from the Pike River. The other bays have much lower color and higher Secchi transparency in comparison. In general, TP is slightly lower and Secchi is higher in the West basin as compared to the East (Table 6). Other parameters such as alkalinity, conductivity and chloride tend to be slightly lower in the West as well. Chloride is high relative to typical concentrations in the NLF ecoregion. Potential sources of excess chloride may be from road salt and runoff from taconite mine tailings. Chloride concentrations are approximately 190 mg/L in Minntac’s tailing basin (MPCA data). It is important to note that while these Lake Vermilion values are high relative to minimally impacted lakes in the NLF ecoregion they are much lower than concentrations encountered in more urbanized portions of the state (Heiskary and Wilson, 2005) and are far below the state water quality standard.

Carlson’s overall TSI on the entire lake indicate mesotrophic conditions. The individual TSI estimates for TP, Chl-a, and Secchi transparency align very well on a lake-wide basis. For Pike Bay, these measures were not in synch. Due to the naturally tannin stained water, Secchi transparency and Chl-a were lower than is expected at its given TP concentration.

TP, Chl-a concentrations, and Secchi transparency data for each site are shown in Figures 20 and 21 (grouped by East and West sites). In general, these parameters did not vary significantly throughout the monitoring season at most sites. TP usually ranged from 20-30 ug/L from May – September. Pike Bay exhibited a distinct increase in TP, and Chl-a and a decline in Secchi over the course of the summer (Figure 20). This pattern is similar to other shallow lakes (Figure 5) and is the result of warm temperatures, adequate sunlight, and abundant nutrients (a portion of which are recycled within the lakes- a result of in-lake processes and wind mixing). In other bays like Big, Frazer, and Armstrong a mid to late-summer increase in Chl-a, accompanied by a decline in Secchi occurred, which is common in many lakes. The September increase in TP that occurred in many of the bays (e.g. Big, Frazer, Niles and Trout) is likely the result of the onset of fall mixing of the lake, which was underway at that time.

Abnormally high water in the first half of the monitoring season (Figure 9) did not appear to have a consistent affect across Lake Vermilion. The relatively stable TP concentrations in Pike and Big Bays in 2008 may be the combined result of a steady influx of TP from the Pike River as well as wind resuspension of fine particles (e.g. clays) from shallow water sediments (which would include all of Pike Bay) throughout the summer. As lake in-flows and levels dropped by late summer, internal recycling and wind resuspension may become even more important in serving to maintain TP concentrations in these shallow windswept bays.

Sulfate concentrations in Lake Vermilion were relatively high in 2008. The lake-wide average (10.6 mg/L) slightly exceeded the water quality standard of 10 mg/L. Concentrations were highest in Big Bay, and were lower and below the standard in the western arm of the lake. The DNR has recently done extensive sampling for sulfate in the mining regions of northeastern Minnesota (Bavin and Berndt, 2008). Sulfate concentrations in lakes and rivers in non-mining impacted watersheds are typically below 10 mg/L, which suggests mining significantly increases sulfate in the watersheds near mines (Bavin and Berndt, 2008). Data from the recent National Lakes Assessment Program (U.S. EPA, summer 2007) can help place these concentrations in perspective as well. Based on 27 randomly-selected lakes in the NLF ecoregion, the inter-quartile range of sulfate was 1.4-3.5 mg/L and only one lake exceeded 10 mg/L. As we consider possible sources of excess sulfate to the lake, a survey of the Sandy River (tributary to the Pike River) may prove informative. Based on that work, the Sandy River average water sulfate concentration was 118 mg/L, approximately 12 times the state standard (Minntac 2004 EIS). Minntac tailings basin seeps draining to the Sandy River had an average sulfate concentration of 828 mg/L in 2008 (MPCA data). Further monitoring may be needed to more fully

Lake Vermilion CLMP+ Water Quality Report • March 2009 32 Minnesota Pollution Control Agency discern sources of excess sulfate to the lake and how sulfate cycles within the lake; however based on Minntac (2004) the Sandy River appears to be an important source of sulfate into Lake Vermilion.

Table 6. 2008 Summer-mean Water Quality Data and NLF Ecoregion Typical Range. East End West End

Parameters Pike Bay Big Bay Arm- Frazer Trout Niles Wakemup Head of Lake- Typical Site 116 Site 130 strong Bay Bay L. Bay Bay The Lakes wide Range for 134 Site 132 Portage Site 102 Site 131 Bay Average NLF Site 113 Site 133 Ecoregion Total 28 20 27 23 18 22 22 22 23 14-27 Phosphorus (± 2 ) ( ± 1.5) (± 2.5) ( ± 2.9) ( ± 2) ( ± 1.7) ( ± 1.8) (± 1.8) (µg/L) (± SE ) Chlorophyll 3.2 6.8 7.5 6.1 4.1 5.6 4.2 4.7 5.3 4 - 10 a (µg/L)3 ( ± 0.5) ( ± 1.1 ) (± 1.1) ( ± 1.1 ) ( ± 0.4 ( ± 0.9 ) ( ± 0.7) (± 0.4) (± SE) ) Maximum 6.6 11.6 11.5 12.1 5.7 10.7 8.4 6.9 < 15 Secchi disk 1.1 2.0 2.1 2.3 2.6 2.7 3.3 2.9 2.3 2.4 – 4.6 (m) (+ / - SE) ( ± 0.1) ( ± 0.1 ) ( ± 0.2 ) ( ± 0.1 ) ( ± 0.1) ( ± 0.1 ) ( ± 0.2 ) ( ± 0.2 )

Secchi Disk 3.6 6.6 6.8 7.4 8.3 8.8 10.9 9.4 7.8 7.9- 15.0 (ft) (± SE) ( ± 0.2) (± 0.3) ( ± 0.6) (± 0.4) (± 0.3) (± 0.6) ( ± 0.8) (± 0.7) TKN (mg/l) 0.8 0.6 0.7 0.5 0.5 0.5 0.4 0.7 0.6 < 0.75 Alkalinity 31 33 28 30 23 30 21 19 27 40 - 140 (mg/l) Color (Pt-Co 113 60 60 37 45 25 25 35 50 10-35 Units) pH (SU) 6.8 7.2 6.6 6.9 6.7 7.1 7.0 6.6 6.9 7.2 – 8.3 Chloride 8.8 8.4 7.7 7.4 4.8 7.0 4.2 4.1 6.6 0.6 – 1.2 (mg/l) Sulfate 10.6 14.8 12.5 12.7 9.6 12.5 6.3 6.1 10.6 (mg/L) T. Sus. Sol. 3.1 3.0 2.0 2.6 1.6 1.8 1.6 1.7 2.2 <1 - 2 (mg/l) T. Sus. 2.2 2.2 1.2 1.9 1.2 1.5 1.4 1.4 1.7 <1 - 2 Inorganic Conductivity 120 132 111 121 89 116 73 70 104 50 - 250 (µmhos/cm) TN:TP Ratio 29:1 29:1 26:1 22:1 27:1 23:1 18:1 32:1 26:1 25:1-35:1

Lake Vermilion CLMP+ Water Quality Report • March 2009 33 Minnesota Pollution Control Agency

Figure 19. TSI Values for Pike Bay and Entire Lake Vermilion Basin

. 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 TRANSPARENCY (METERS)

0.5 1 2 3 4 5 7 10 15 20 30 40 60 80 100 150 CHLOROPHYLL-A (PPB)

3 5 7 10 15 20 25 30 40 50 60 80 100 150 TOTAL PHOSPHORUS (PPB)

NLF Ecoregion Range: Vermilion- Lakewide : Vermilion- Pike Bay:

After Moore, l. and K. Thornton, [Ed.]1988. Lake and Reservoir Restoration Guidance Manual. USEPA>EPA 440/5-88-002.

Lake Vermilion CLMP+ Water Quality Report • March 2009 34 Minnesota Pollution Control Agency

Figure 20. 2008 TP, Chlorophyll-a and Secchi Transparency Data for East End Sites.

Pike Bay Big Bay

60 0 40 0 55

50 -3 ) -5 ft (

45 30

y 40 35 -6 -10 arenc p 30 20 25 -9 -15

C oncentration 20 15 (ug/L) Concentration 10 Secchi Transparency (ft) Transparency Secchi -12 Trans Secchi -20 10 5 0 -15 0 -25 Mid May E arly Late Early JulyLate July Early Late Aug. Early Late Mid May Early Late Early Late Early Late Early June June Aug. Sept. Sept. June June July July Aug. Aug. Sept.

Total P. (ug/L) Chl A. (ug/L) Secchi (ft) Total P. (ug/L) Chl A. (ug/L) Secchi (ft)

Frazer Bay Armstrong Bay

60 0 80 0 ) ft

) 50 (

-5

/L -5 y

60 ) g ) ft u (

( 40 /L y g arenc u

( -10 p

30 -10 arenc 40 p

20 -15 -15 Concentration Concentration Concentration 10

20 TransSecchi S Trans ecchi -20 0 -20 Mid Early Late Early Late Early Late Early Late May June June July July Aug. Aug. Sept. Sept. 0 -25 Mid May Early June Late June Early July Late July Early Aug. Late Aug. Early Sept.

Total P. (ug/L) Chl A. (ug/L) Secchi (ft) Total P. (ug/L) Chl A . (ug/L) Secchi (ft)

Lake Vermilion CLMP+ Water Quality Report • March 2009 35 Minnesota Pollution Control Agency

Trout Lake Portage Niles Bay

50 0 50 0

40 -4 ) ) ft

( 40 -5 )

ft ( y

/L y g u ( 30 -8

arenc 30 -10 arenc p p

20 -12 20 -15 Concentration C oncentration C oncentration

10 -16 Secchi Trans 10 -20 Trans Secchi

0 -20 0 -25 Mid May Early Late June Early July Late July Early Aug. Late Aug. Early Mid May Early Late June Early July Late July Early Aug. Late Aug. Early June Sept. June Sept.

Total P. (ug/L) Chl A. (ug/L) Secchi (ft) Total P. (ug/L) Chl A. (ug/L) Secchi (ft)

Wakemup Head of the Lakes

60 0 45 0

50 -5 40

) -5 ) ft

( 35 ft

(

40 -10 y 30 -10 arenc p 25 arenc 30 -15 -15 p 20

Concentration 20 -20 15 -20 Concentration

Secchi Trans Secchi 10

10 -25 -25 TransSecchi 5

0 -30 0 -30 Mid May Early June Late June Early July Late July Early Aug. Late Aug. Early Sept. Mid May Early June Late June Early July Late July Early Aug. Late Aug. Early Sept.

Total P. (ug/L) Chl A. (ug/L) Secchi (ft) Total P. (ug/L) Chl A. (ug/L) Secchi (ft)

Figure 21. 2008 TP, Chlorophyll-a and Secchi Transparency Data for West End Sites

Lake Vermilion CLMP+ Water Quality Report • March 2009 36 Minnesota Pollution Control Agency

Trends in Trophic Status and Water Quality

Comparison between 2000 and 2008 Lake Assessments

Of the eight sites sampled in 2008, three were also sampled in the MPCA’s 2000 study – Pike, Big, and Wakemup bays. A comparison of summer-mean TP, Chl-a, and Secchi transparency at the three sites and a lake-wide average for both years is provided in Figure 22. Based on this comparison there was no significant difference in TP, Chl-a, or Secchi transparency on a lake-wide basis. Likewise there was no significant difference among the 2000 and 2008 TP and Secchi means for the three bays. As an aside, the 2000 and 2008 lake-wide averages were not calculated from the same set of monitoring stations. In 2000, only four sites were sampled, one of them being the Vermilion River at the Lake’s outlet- which was not sampled in 2008.

There was a difference in Chl-a, in Wakemup and Pike Bays (Figure 22). In both cases, the 2008 values were lower than the 2000 values for these two bays. This was likely due to some high individual concentrations collected during a late summer algae blooms in 2000 and is reflected in the larger standard error bars for 2000. Wakemup concentrations peaked in August 2000 at 16 micrograms per liter (ug/L - versus 8 ug/L in 2008). Pike Bay concentrations peaked at 26.5 ug/L in 2000, versus only 6.5 in 2008. A nuisance algae bloom was noted in Pike Bay in August 2000, while bloom conditions were not observed by MPCA staff or SCLV volunteers during any 2008 sampling event.

In summary, these data suggest that water quality in Lake Vermilion has not changed significantly from 2000 to 2008 – though algal response may vary somewhat between years.

Mid-Summer Water Quality Data: 1988 – 2008 (DNR)

Since 1988, the DNR has been collecting water quality samples at their five stations. All five of the DNR’s stations were sampled by MPCA and SCLV in 2008 (Big, Trout, Frazer, Niles, and Wakemup bays). Because these individual samples are collected at about the same time of the year over the long term, they provide a good general indicator of mid-summer water quality and can be used to further help identify potential temporal changes in water quality.

These TP, Secchi, and Chl-a data were provided to the MPCA and the non-parametric Mann Kendall trend test was performed on the 21 years of data (Trout Bay data has been collected since 1996 so 13 years of data are available at that site). No temporal trends were detected in the Secchi data at any site. Two sites showed statistically significant ( α = .05) declines (i.e. improvement) in the other parameters – TP at the Trout Lake portage, and chlorophyll-a in Wakemup Bay (Figure 23).

Citizen Lake Monitoring Program Secchi Transparency Trend Data

MPCA’s CLMP database provides another option for assessing trends and patterns in water quality for Lake Vermilion. In this case, a lake-wide summary and data from two individual sites, with extended data records, were used for this purpose. The Mann Kendall statistical test for trends was performed on the average as well as individual mid-summer values. The two CLMP sites with the longest continuous record have data starting in the mid 1990’s. Site 203 is located southeast of Pine Island, courtesy of volunteer Steven Lotz, the other is site 218 in Big Bay (~1 mile S. of the Big Bay site sampled in this study) courtesy of Mel and Ellen Hintz. Figure 24 shows the summer average Secchi transparency at the two CLMP sites, and the lake-wide annual average (which includes CLMP data as well as data from the MPCA and cooperating agencies).

Lake Vermilion CLMP+ Water Quality Report • March 2009 37 Minnesota Pollution Control Agency

Figure 22. Summer-mean TP, Chl-a, and Secchi for 2000 and 2008. Red bars are ± 1 standard error.

Total Phosphorus (ug/L) 10

0 Pike Bay Big Bay Wakemup Lake-wide

2000 TP (ug/L) 2008 TP (ug/L)

6 Chlorophyll a (ug/L)

0 Pike Bay Big Bay Wakemup Lake-wide

2000 Chl.-a (ug/L) 2008 Chl.-a (ug/L)

10 Secchi Transparency (ft)Secchi Transparency

14 Pike Bay Big Bay Wakemup Lake-wide

2000 Secchi (ft) 2008 Secchi (ft)

Lake Vermilion CLMP+ Water Quality Report • March 2009 38 Minnesota Pollution Control Agency

Figure 23. Trends in August Chl-a Concentrations at DNR’s Wakemup Bay Site. Data supplied courtesy of Duane Williams, MN DNR Fisheries.

Wakemup Bay Annual Chlorophyll-a Concentrations

Chlorophyll-a (ug/L) Chlorophyll-a 10

0 88 90 92 94 96 98 00 02 04 06 08

The two CLMP sites do not show a significant change in transparency since the mid-1990’s in either the average or mid-summer values; however, the lake-wide dataset does exhibit a significant improvement in transparency since the 1970’s. This apparent “lake-wide” trend, though, may be the product of a couple factors: 1. In the 1970’s, monitoring was focused in Pike Bay and Big Bay, areas with naturally lower transparency. Since the 1980’s, more data was collected in the main basin, including the West basin which naturally has a higher transparency. 2. During the 1970’s, the Tower and Soudan wastewater treatment ponds had not yet been upgraded to address phosphorus and the impact from the ponds would have been most pronounced in Pike and Big Bays as compared to the more distant bays of the lake. The ponds have been treated with alum to remove phosphorus since the early 1980’s, and discharge treated wastewater to a tributary of the East Two River.

Annual mean transparency has been relatively stable in Lake Vermilion since the late 1980’s (Figure 24). The long term annual mean transparency is 7.5 feet; however, there are some distinct cyclic patterns in transparency. For example, the periods from 1987-1993, 1996-2001, and 2004-2008 are characterized by declines in transparency (Figure 24). Sites 203 and 218 exhibit similar patterns of increasing transparency for the period 2000-2004 followed by a distinct decline for the period 2004-2008 (Figure 24). Lake levels may play some role in this pattern, e.g. 2001 and 2008 summers of low transparency were characterized by extended periods where levels were above the OHWL and well above the long-term average (Figure 10). Summers of 1998 and 2004 with above-average transparency had lake levels below the OHWL and in the range of long-term average. While this analysis is far from conclusive on causes for fluctuations in transparency it does suggest that lake level may be one of the factors that influence transparency in Lake Vermilion.

In summary, when looking at the entire historical dataset- MPCA and DNR assessments, and CLMP data - we can conclude that Lake Vermilion water quality has not significantly changed since comprehensive monitoring began about 20 years ago.

Lake Vermilion CLMP+ Water Quality Report • March 2009 39 Minnesota Pollution Control Agency

Figure 24. Trends in Lake Vermilion Secchi Transparency Data for: Site 203, 218, and Lake-wide Average. Red bars represent standard error of the mean.

CLMP Data Site 203, SE of Pine Island Courtesy of Volunteer Steven Lotz

0.00

2.00

4.00

6.00

8.00

Annual Secchi mean (Feet) 10.00

12.00 1994 1995 1996 1997 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

CLMP Data Site 218- Big Bay. Courtesy of Mel & Ellen Hintz

0.0

2.0

4.0

6.0 ean Secchi (Feet) 8.0 nnual M

A 10.0

12.0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Lake Vermilion Lake-wide Annual Mean Secchi Transparency

10 Mean SecchiMean Transparency (Feet)

12 76 77 79 81 82 83 84 85 86 87 88 89 90 91 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08

Lake Vermilion CLMP+ Water Quality Report • March 2009 40 Minnesota Pollution Control Agency

Modeling

MINLEAP

Observed and predicted P for Pike Bay were not significantly different (28 and 39 µg/L). The predicted Chl-a concentration (based upon predicted TP) is 13.9 µg/L, which is significantly different than the measured value for 2008. This difference may be due to the naturally high color (“bog stain”) in the water, which can limit algae growth and is not accounted for in the model. Predicted transparency is slightly higher, but not significantly different, than observed (Table 8). The model also estimates the frequency of occurrence of nuisance (> 20 µg/L Chl-a) and severe nuisance (> 30 μg/L Chl-a) algal blooms. Based on the observed summer-mean Chl-a of 3.2 µg/L and data for 2008 (Figure 20) nuisance blooms did not occur in 2008. In contrast, at a predicted concentration of 13.9 μg/L, nuisance blooms could occur about 16 percent of the summer.

The Pike River is the single largest tributary to Lake Vermilion and is the primary contributor of the water and P load (Table 7a). Because of its small volume and large water loading from the Pike River, the water residence time (time it would take to fill the bay if it were empty) for Pike Bay is very short – on the order of 30 days (0.1 years). The areal water load (water load from runoff and precipitation divided by lake surface area) is about 14 m/yr and outflow from the lake is estimated at 130 cubic hectometers per year (~ 145 cubic feet per second - cfs) based on the inputs used in MINLEAP.

Similar estimates were made for the lake as a whole as presented in Table 7b. Predicted P is slightly lower (but not significantly different) than observed, and as a result, predicted Chl-a and Secchi are not significantly different as well. Because of the much larger volume relative to the watershed (Table 2), the residence time of the lake is much longer and is on the order of 3.6 years. The lake retains about 65 percent of the P load based on MINLEAP.

A regression model (Vighi and Chiaudani, 1985), based on the morphoedaphic index commonly used in fishery science, was used to estimate “background” TP for Pike Bay and Lake Vermilion. This model predicts TP based on mean depth and alkalinity. Based on this equation, background TP for Pike Bay and Lake Vermilion was estimated at 21 and 12 µg/L respectively. While alkalinity is similar between Pike Bay and Lake Vermilion, Pike Bay is substantially shallower, which contributes to the higher background concentration and makes sense given the large watershed that drains to it.

Lake Vermilion CLMP+ Water Quality Report • March 2009 41 Minnesota Pollution Control Agency

Table 7a. Comparison of observed and model predicted values- Pike Bay

Parameter 2008 MINLEAP BATHTUB Observed Predicted Predicted TP (µg/l) 28 ± 2 39 ± 8 23.5 chl-a (µg/l) 3.2 ± 0.5 13.9 ± 6.5 8.1 % chl-a > 20 µg/l 16 3.9 % chl-a > 30 µg/l 3 0.8 Secchi (m) 1.1 ± .1 1.6 1.0 P-loading rate (kg/yr) -- 6,603 6,655

% P retention -- 23

P inflow conc. (µg/l) -- 50 water load (m/yr) -- 14 outflow volume (hm3/yr) -- 130 “background P” -- 20.5 residence time (years) -- 0.1 0.11

Table 7b. Comparison of observed and model predicted values-Vermilion main basin

Parameter 2008 MINLEAP BATHTUB Observed Predicted Predicted TP (µg/l) 22 ± 2 16 ± 5 23 chl-a (µg/l) 5.6 ± 0.7 3.7 ± 2.2 7.9 % chl-a > 20 µg/l 7 0 3.5 % chl-a > 30 µg/l 0 0 0.7 Secchi (m) 2.3 ± 0.1 3.6 ± 1.4 2.1 P-loading rate (kg/yr) -- 12,439 19,199 (12,8441 ) % P retention -- 65 73 P inflow conc. (µg/l) -- 45 water load (m/yr) -- 1.75 outflow volume (hm3/yr) -- 278 225 “background P” -- 12.2 residence time (years) -- 3.6 4.1 1. excludes internal loading 1. Excludes internal loading

BATHTUB

The BATHTUB model provides a further basis for estimating water and nutrient budgets for the Lake Vermilion watershed using a combination of runoff , P export coefficients based on land use in the watershed, and data from similar systems in this ecoregion. This model allows for the “routing” of water and nutrient loads between the basins. In this fashion, improved estimates of nutrient and water exchange can be obtained and improved estimates of in-lake condition should be possible.

For this effort, we divided the lake into two distinct basins: Pike Bay and the main-basin, versus four basins in our 2000 model run. This was done to simplify inputs, since water quality did not significantly vary among the main basin sites (Table 6) and we lacked actual monitoring data for inflows to the various sub-basins. As has been previously discussed, Pike Bay has unique hydrology, morphology, and water quality and warrants separation from the rest of the lake. To make the 2000 and 2008 model runs as comparable as possible, model inputs were not changed unless new information and data became available to increase the model’s accuracy. Specifics on the model inputs are detailed below.

Lake Vermilion CLMP+ Water Quality Report • March 2009 42 Minnesota Pollution Control Agency

Reference to “direct or immediate” drainage is meant to imply that portion of the watershed that drains directly to the lake via small tributaries without passing through a major lake. This would include much of the land around the western portion of the lake (Head of the Lakes, Wakemup, and Niles Bay, and subwatersheds to the east of Big Bay). In other instances, runoff may flow through significant lakes such as Trout Lake. These lakes will retain much of the P generated from the subwatershed and as such are addressed differently in the modeling effort. Additional estimates and inputs to the model are as follows.

Significant changes to 2008 inputs versus the 2000 model are also summarized in Table 8:

1. Septic loading was based on a total of ~ 2,950 residences around the lake as supplied by the St. Louis County Planning Department (based on 911 records, or “fire numbers”). This is about a 21% increase in developments since 2000 (2,330 residences). The estimates on use and system performance were the same as 2000 (Anderson and Heiskary, 2001). We estimated about 80 percent were seasonal and the remainder year round residences. This allowed for P loading estimates from septics based on: 2.2 capita per residence, estimated days of use (seasonal vs. year round), standard P loading per capita, and P retention by septic systems and soils ranging from “high retention” of 90 % to a “low retention” of 60 %. High retention is anticipated for well-maintained systems in good soils and poor retention is anticipated for poorly maintained systems in poor (e.g. water-logged soils). For this model run, we selected 70 percent retention which translates to a loading rate of 880 kg P/yr reaching the lake. This is a 10 % increase as compared to the 2000 model run. We assume that St. Louis County’s septic system point of sale ordinance (which mandates a system functions properly or be replaced before a sale), has had a beneficial effect by reducing the TP load to Lake Vermilion. We assume that the 20% increase in development resulted in only a 10 % increase in TP loadings from septic systems (800 kilograms in 2000 versus 880 in 2008). A reasonable bracket might be 80 percent (588 kg P/yr) to 60 percent (1,174 kg P/yr). This estimate was then subdivided among the basins based on the estimated intensity of development (septic systems) around the lake: Pike Bay (10%), remainder of lake (90%). 2. P export coefficients - standard coefficients based on the literature and past experience were used. These were applied to lands in the “immediate” watershed of Lake Vermilion (islands and near shore). These values vary by land use type (forest, wetland, and urban for this watershed) and were appropriately applied to the lake based on the most recent land use data (Figure 7, Table 4). New data available since 2000 improved the accuracy of this estimate. 3. Precipitation was based on data from the surrounding area in 2008. The 2008 water year (October 1, 2007 to September 30, 2008) precipitation in Tower was 30.7 inches, a 16% increase over 2000. Runoff was estimated from USGS records for the Vermilion River as measured at Crane Lake; it slightly increased (~ 15%) in 2008 because of the greater precipitation. 4. Atmospheric deposition rate of 15 kg P/km2/yr was used. 5. P concentrations for runoff from Trout Lake, Pike River, and Two Rivers were estimated from recently available data. The Trout Lake concentration was selected as 10 ug/L, based on a 2006 Lake Assessment conducted on Trout Lake by the MPCA. TP concentrations in the Pike River were estimated at 50 ug/L. This is slightly higher than the 2000 estimate of 40 ug/L. The higher number was used to account for the extreme high water in 2008, which likely increased overall TP load to the Lake. The Two Rivers TP concentration was estimated to be 40 ug/L (versus 50 ug/L in 2000). This value was based on recent lake monitoring in Eagles Nest Lakes, which form the headwaters of the E. Two River, where concentrations average about 25 ug/L. Slight increases in TP are expected downstream due to storm-water runoff from the city of Tower. 6. Point sources – Measured discharge and concentration data were used for the Tower WWTF. The figure of 128 kg / year was the average of the actual 2007 and 2008 wastewater monitoring data provided to the MPCA. Values for Soudan State Park were excluded, since the inflows to Lake Vermilion are groundwater discharge and the flows are very low ( 0.15 cfs, or 0.1 % of Pike Bay’s inflow) and no TP data are available. Estimates of the TP load from Fortune Bay Resort’s wastewater ponds were also excluded from BATHTUB, because discharge data were not available. It is reasonable to estimate the TP load to Lake Vermilion is equal to or slightly less than Tower’s given the pond’s size. 7. Internal loading was used as an input for Pike Bay as a means to balance the “observed” in-lake P with “estimated.” This was deemed reasonable based the shallowness of the Bay and the likelihood of wind resuspension of P from bottom sediments. The internal loading rate used in 2008 was double the rate used

Lake Vermilion CLMP+ Water Quality Report • March 2009 43 Minnesota Pollution Control Agency

in 2000. This value of 2 mg/m2/day was still deemed reasonable and is based on literature values from other Minnesota lakes. The actual phosphorus release rates from the Pike Bay sediments are unknown.

Good agreement was obtained between observed and predicted P for the segments, especially the main basin (Tables 8 & 9). In the case of Pike Bay, this was achieved by including a term for “internal loading” of P. This seemed reasonable based on the shallowness, susceptibility to wind mixing, and the limited exchange with the main basin of the lake. Internal loading was not used for the remainder of the lake – though it could account for a portion of the underestimate of P in these basins as well. In general, there is good agreement between observed and predicted Chl-a and Secchi values for each basin. This suggests Lake Vermilion is generating the amount of algae we would expect based on measured P and standard regression equations.

Pike Bay represents about 1.5 % of the volume of Lake Vermilion but receives runoff from about 40 percent of the watershed via the Pike River and East and West Two Rivers (Table 6). These three rivers account for the vast majority of the external loading to Pike Bay and about 60-65 percent of the total loading (external plus internal). In comparison, on-site septic systems and the Tower WWTF discharge contributed on the order of five percent of the P loading.

When the internal loading estimates are removed from the phosphorus budget, the loads are very similar from 2000 to 2008- about 12,500 kilograms (Table 8). Figure 25 shows the relative contribution from the seven major external sources of TP to Lake Vermilion, based on the 2000 and 2008 BATHTUB model estimates. Where noted, new information improved the accuracy of TP loads, and therefore improved accuracy of previous estimates

• The Pike River watershed portion increased to approximately 42 %. We estimate TP loads increased due to the abnormally high precipitation and lake levels observed in the spring and summer of 2008 (Figures 8 and 9). • The Two Rivers watershed contribution is about 6% of the TP load. The “true” load likely did not decline by 50% since 2000. The newer estimate is likely more accurate assuming land use did not change significantly. 2008 monitoring data in the Eagles Nest Lakes, which form the watershed’s headwaters, and improved watershed mapping tools are responsible for the difference • The City of Tower’s wastewater remains a very small portion of the Lake’s TP budget, around 1-2 percent. The WWTF remains in compliance with discharge limits and is functioning properly. Improvements in wastewater treatment operations are likely responsible for the 50 percent reduction in TP loads from 2000 to 2008, according to MPCA staff. • Direct runoff to the lake. The proportion of developed land was probably over-estimated in 2000, in keeping with the strategy of conservative estimates of TP loads. New Geographic Information System (GIS) maps and land cover data improved the accuracy of this estimate. • Septic systems remain about 6-7 % of the relative TP load. As discussed previously, the increase in TP from additional developments likely is partially offset by St. Louis County’s point-of-sale ordinance. • Precipitation increased 16% from 2000 to 2008, so this portion of the TP load increased accordingly. • Trout Lake watershed- “true” load was probably unchanged from 2000 to 2008 because landuse did not change in this watershed that is within the Boundary Waters Canoe Area Wilderness. New water quality data from Trout Lake improved the 2008 estimate. • Internal loading, which represents P recycled from the sediments, is common in both shallow, well- mixed lakes as well as deep, thermally-stratified lakes. It is not shown in Figure 25 because these values are estimated in an attempt to balance observed versus BATHTUB predicted TP values. In deep lakes, internal recycling is typically associated with oxygen-poor conditions that allow P to be released as iron-bearing compounds in the sediment lose their ability to adsorb P. In most cases, this “internal” source of P is retained in the deep hypolimnetic waters until fall mixing. In shallow lakes, internal P release is often caused by several processes including: wind resuspension of sediments and bacterial decomposition of organic matter in the sediments. This release is enhanced by warm temperatures and release rates are often greatest as temperatures rise above 17 degrees C at the sediment surface – as was the case for Pike Bay throughout the summer of 2008 (Figure 11). In shallow lakes this P is rapidly recycled into the system. An aerobic release rate of 2 mg/m2/day was used to balance the P budget for Pike Bay. This value was double what was used in 2000. This value

Lake Vermilion CLMP+ Water Quality Report • March 2009 44 Minnesota Pollution Control Agency

is on the low end based on the literature and is much lower than release rates measured for highly eutrophic Lake Pepin (2.7 – 7.8 mg/ m2/day). For Pike Bay it was estimated that this “internal” source could account for almost a third of the P loaded to the Bay (based on the measured P concentration for the Bay). As we noted, this was done to balance the P budget for the Bay and, as such, we cannot ascertain the accuracy of this estimate. Improving the estimate of external loading to Pike Bay and/or actually measuring sediment release rates in the laboratory could allow for refinement of these rates.

Table 8. 2008 and 2000 Estimated Lake Vermillion Total Phosphorus Budget from BATHTUB Model

Phosphorus Source 2008 Load in 2000 Load in Explanations on Differences – 2000 vs. Kilograms Kilograms 2008 ( % of Total ) ( % of Total ) Pike River Watershed 5,350 (27.8 % ) 3,560 (23.3 %) Very high water levels in Pike River in Spring 2008. Increased TP inflow from 40 to 50 ug/L to account for likely higher concentrations in runoff. Future efforts should include Pike River monitoring data Two Rivers Watershed 760 (3.9 % ) 1,450 (9.4 %) Lowered TP inflow concentration from 50 to 40 ug/L, based on new data from Eagles Nest Lakes. More accurate figures on drainage area used in 2008 City of Tower 128.5 (0.6 %) 246 (1.6 %) 2008 estimate matches actual monitored Wastewater wastewater data provided to MPCA Direct Runoff to Lake 2,325 (12.1 %) 3,531 (23.1 %) Improved GIS data increased accuracy of drainage area and land cover classifications. TP export concentrations from forest, wetland, and urban land uses unchanged. Slight decrease in watershed runoff values from 2000, based on USGS Vermilion River flow gage. Septic Systems 880 (4.5 %) 800 (5.2 %) 21 % increase in number of lake shore developments from 2000 to 2008; very likely that some impact is offset by County point-of- sale ordinance Trout Lake Watershed 265 (1.3 %) 530 (3.4 %) Recent Trout Lake water quality data improved TP estimate, from 20 to 10 ug/L (i.e. a 50% reduction) Precipitation 3,136 (16.3 % ) 2,461 (16.1 %) 2008 was a wetter year than 2000. 30.7 inches versus 25.2 inches in 2000 Internal Load 6,355 (33 %) 2,697 (17.6 %) Estimated to help balance observed versus predicted concentrations in Pike Bay. Aerobic internal recycling of P is likely because of shallowness of Bay, warm temperatures above sediments, and potential for wind resuspension. Actual P release rates are unknown. Grand Total 19,199 (100 % ) 15,277 (100 %)

Total Load Minus 12,844 (67 % ) 12,580 (82.4 %) Very similar values. These reflect observed Internal Loading water quality data showing no significant change from 2000 to 2008.

Lake Vermilion CLMP+ Water Quality Report • March 2009 45 Minnesota Pollution Control Agency

Figure 25. 2000 and 2008 Estimated Relative Phosphorus Contributions (%) from External Sources (excludes groundwater).

2000 Phosphorus Loading

6 2 4

Tower WWTP 28 Pike River Watershed Two Rivers Watershed

28 Precip Direct Runoff Trout Lake Watershed

Septic Systems 12

2008 Phosphorus Loading

7 1 2 Tower WWTP Pike River Watershed 18 Two Rivers Watershed 42 Precip Direct Runoff Trout Lake Watershed

Septic Systems

Model Review and Best Management Practices

While numerous assumptions were made in the modeling of Lake Vermilion, the results provide some general themes that can be useful as we think about next steps in the management of the lake. The Pike River and East and West Two Rivers are the largest tributaries (drain about 44 % of the total watershed) and most likely are the largest external source of P to Lake Vermilion (Figure 25). Since these rivers drain to Pike Bay, which contains about one percent of the lakes’ volume, they will dominate the water quality of Pike Bay. In contrast, other subwatersheds like Trout Lake, which drains about 10 % of total watershed, contribute a rather small percentage of the P load. Precipitation on the lake is a significant portion of the water and P budget because of Lake Vermilion’s large surface area and relatively small watershed. The wastewater discharge from the City of Tower, while an important source, contributes a small portion of the P load to the lake.

On-site septic system loading to the lake may be a small portion of the P load (about 7 percent when excluding internal sources of TP) based on the information we had available and the techniques we used to make our estimates. Should systems or soils around the lake retain less P (70 %) than we used in our assumptions the relative contribution from this source could be greater (and likewise if the systems retain more it would contribute less).

Lake Vermilion CLMP+ Water Quality Report • March 2009 46 Minnesota Pollution Control Agency

Of the source-categories we have noted, some might be considered controllable (subject to management) while others are not. Sources that would generally be considered not controllable would include: atmospheric deposition of P on the lake, background runoff from forest and wetland areas (typical of this landscape), and diffusive sources (mixing within the lake). Those sources that can be viewed as controllable would include: a portion of the septic system effluent that leaches to the lake, wastewater discharges, a portion of the urban runoff (stormwater) that drains to the lake from driveways, parking lots, rooftops, lawns and other surfaces which contribute runoff and P to the lake. While septic systems appeared to be a small contributor (on a lake- wide basis) it may be among the most “controllable” portion of the P loading to the lake considering that atmospheric and natural background loads cannot be reduced. Property owners should take a personal responsibility to properly maintain their system. Every TP source, no mater how small, prevented from reaching the lake will be beneficial in the long run. Although actual monitoring data are not available on Lake Vermilion, it is a reliable assumption that newer septic systems perform better than older ones, and that St. Louis County’s point of sale ordinance is having a beneficial affect by protecting Lake Vermilion. In addition to annual inspection and septic system maintenance (pump as needed) and updating systems that may not be up to code, other suggested lakeshore best management practices property owners can do to protect Lake Vermilion’s natural environment may include: • Maintain buffer areas of natural vegetation between their lawns and the lakeshore and minimize removal of aquatic vegetation. These can filter runoff and benefit the fishery and aquatic life. • Minimize the amount of manicured lawns on your property. If you must use fertilizers, use those that do not contain phosphorus. • Conserve water in your home or cabin. This will reduce stress on your septic system and the lake • In the shoreland areas, setback and stormwater provisions should be strictly followed and the amount of impervious area (roads, rooftops, and parking lots) should be minimized. Studies have shown that the TP originating from these “non-point” sources can be greater that the TP originating from septic systems.

303(d) Assessment and Goal Setting

Minnesota waters are assessed on a biennial basis for compliance with water quality standards as a part of the Clean Water Act. Those that do not meet standards are placed on the 303(d) list of impaired waters, which is submitted to U.S. EPA for approval. Waters on this list require development of a Total Maximum Daily Load (TMDL), which is intended to determine the necessary reductions in a pollutant loading that would allow the water to meet standards.

Aquatic recreation use support is an example of one of the assessments made for lakes in Minnesota. This assessment uses the recently promulgated eutrophication standards as a basis for judging impairment status (Table 9). Details on the derivation of this standard may be found in Heiskary and Wilson (2005). For a lake to be assessed for the 303 (d) process it must have 8 measurements of TP, Chl-a and Secchi collected over the most recent 10 years. Only results collected between June and September are considered in the assessment.

The next assessments will be made in 2009 for the 2010 listing and will consider data collected from 1999- 2008. Table 11 shows the assessment of Lake Vermilion relative to the criteria. If the values exceed the TP, and either the Chl-a or Secchi criteria the lake will be considered impaired, placed on the 303 (d) list and submitted to U.S. EPA.

Lake Vermilion is in the NLF Ecoregion and is classified as a 2B water. The applicable standards are < 30 µg/L TP, < 9 µg/L Chl-a and > 2.0 meter Secchi Transparency. Based on the 2008 data, Lake Vermilion is meeting these standards and is therefore NOT considered impaired (Table 10).

Lake Vermilion CLMP+ Water Quality Report • March 2009 47 Minnesota Pollution Control Agency

Table 9. Minnesota Lake Eutrophication Standards Ecoregion TP Chl-a Secchi

ppb ppb meters NLF – Lake trout (Class 2A) < 12 < 3 > 4.8

NLF – Stream trout (Class 2A) < 20 < 6 > 2.5 NLF – Aquatic Rec. Use (Class 2B) < 30 < 9 > 2.0

NCHF – Stream trout (Class 2a) < 20 < 6 > 2.5

NCHF – Aquatic Rec. Use (Class 2b) < 40 < 14 > 1.4 Deep lakes NCHF – Aquatic Rec. Use (Class 2b) Shallow lakes < 60 < 20 > 1.0

WCBP & NGP – Aquatic Rec. Use (Class 2B) Deep < 65 < 22 > 0.9 lakes

WCBP & NGP – Aquatic Rec. Use (Class 2b) Shallow < 90 < 30 > 0.7 lakes

Table 10. Lake Vermilion 303d Assessment Summary

Parameter NLF Ecoregion Lake Vermilion Lake Vermilion Lake Standard (2B) – Entire Lake – Pike Bay Vermilion- Main Basin Total Phosphorus (µg/l) <30 22.7 29 21.8 Chlorophyll mean (µg/l) < 9 5.3 3.4 3.4 Secchi Disk (meters) > 2.0 2.3 1.1 2.5

If the SCLV and area management agencies desire a supplemental water quality management goal, based on observed data and model estimates, a reasonable P goal for Pike Bay may be in the 25 to 30 µg/L range. At 25µg/L nuisance blooms should not occur and mild blooms should occur less than about 10 percent of the summer. For the remainder of the lake, a P goal of 20 µg/L or less should be reasonable. At 20 µg/L, nuisance blooms should not occur and mild blooms should occur less than five percent of the summer. Secchi should average on the order 2.5 – 3.0 m over the summer – with the exception of bays that may be more highly colored. At this point, it is difficult to refine these goals any further or to determine the long-term achievability of the goals. Our data and model estimates do, however, provide some general direction on which subwatersheds should be priorities for future monitoring and what might constitute “manageable” sources of P to the lake.

In summary, the similarity in measured (i.e. monitored) and modeled water quality in 2000 and 2008 and the lack of significant trends in the long term DNR and CLMP datasets provide multiple lines of evidence that Lake Vermilion’s water quality is relatively stable, generally within typical ranges for NLF lakes and meets NLF lake nutrient standards. It is important for the SCLV and area management agencies to continue their excellent work in protecting the Lake Vermilion watershed. Potential threats to the lake are numerous; such as exotic species invasions, increasing lakeshore development, and global climate change.

Once communities and property owners in the watershed take ownership in the quality of these lakes there is an increased likelihood that measures to improve the lakes will be undertaken. The improvement and protection of the lakes is essential not only for the future of the lake, but the community as well. This is well stated by Krysel, et al. (2003), “The evidence shows that management of the quality of lakes is important to maintaining the natural and economic assets of this region.”

Lake Vermilion CLMP+ Water Quality Report • March 2009 48 Minnesota Pollution Control Agency

References

Anderson, J.A. and S. Heiskary. Lake Vermilion Lake Assessment, 2000. Environmental Outcomes Division. Minnesota Pollution Control Agency, May 2001. http://www.pca.state.mn.us/publications/lar-69-0378.pdf

Bavin, T. and Berndt, M. 2008. Sources and Fate of Sulfate in NE Minnesota Watersheds: A Minerals Coordinating Committee Progress Report. Minnesota Department of Natural Resources, Division of Lands and Minerals, St. Paul, MN

Charles Krysel, Elizabeth Marsh Boyer Charles Parson, Ph. D and Patrick Welle. 2003. Lakeshore Property Values and Water Quality Bemidji State University.

Carlson, R.E. 1977. A trophic state index for lakes. Limnol. Oceangr. 22:361-369.

Heiskary S. and C.B. Wilson. 2005. Minnesota Lake Water Quality Assessment Report: Developing Nutrient Criteria. 3rd Ed. Environmental Analysis and Outcomes Division, MPCA St. Paul MN. http://www.pca.state.mn.us/publications/reports/lwq-a-nutrientcriteria.pdf

Minnesota Department of Natural Resources. Lake Vermilion Lake Level Dataset. http://www.dnr.state.mn.us/lakefind/showlevel.html?id=69037800

Minnesota State Climatology Office. Annual Precipitation Maps http://www.climate.umn.edu/doc/annual_pre_maps.htm

Minntac, 2004. Minntac Water Inventory Reduction Final Environmental Impact Statement Wild Rice Technical Memorandum. US Steel Corporation , Pittsburgh, PA, 58 p.

Vighi, M. and G. Chiaudani. 1985. A sample method to estimate lake phosphorus concentrations resulting from natural background loading. Wat. Res. 19:987-991.

U.S. Environmental Protection Agency. National Lakes Survey http://www.epa.gov/owow/lakes/lakessurvey/

U.S. Geological Survey. Interactive mapping GIS application. http://gisdmnspl.cr.usgs.gov/watershed/start_page.htm

Walker, W., 2004. BATHTUB version 6.1. Simplified Techniques for Eutrophication Assessment and Prediction. USAE Waterways Experiment Station, Vicksburg, Mississippi; April 2004.

Wilson, C.B. and W.W. Walker 1989. Development of lake assessment methods based upon the aquatic ecoregion concept. Lake and Reservoir Management 5(2):11-22.

Lake Vermilion CLMP+ Water Quality Report • March 2009 49 Minnesota Pollution Control Agency

Appendix A Glossary

Acid Rain: Rain with a higher than normal acid range (low pH). Caused when polluted air mixes with cloud moisture. Can make lakes devoid 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. 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: Lakes which thermally stratify and mix (turnover) once in spring and fall.

Ecoregion: 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 microorganisms, 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.

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 to mix with lower levels of water. As in spring turnover, all water is now at the same temperature.

Hypolimnion: The bottom layer of lake water during the summer months. The water in the hypolimnion is denser and much colder than the water in the upper two layers.

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.

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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.

Mesotrophic Lake: Midway in nutrient levels between the eutrophic and oligotrophic lakes

Meromictic A lake that does not mix completely

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.

Photosynthesis: The process by which green plants produce oxygen from sunlight, water and carbon dioxide.

Phytoplankton: Algae – the base of the lake’s food chain, it also produces oxygen.

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. Tends to mix periodically throughout summer via wind and wave action.

Profundal Community: The area below the limnetic zone where light does not penetrate. This area roughly corresponds to the hypolimnion layer of water and is home to organisms that break down or consume organic matter.

Respiration: Oxygen consumption

Secchi Disk: A device measuring the depth of light penetration in water.

Sedimentation: The 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 deeper water. At this time of year, all water is the same temperature.

Thermocline: During summertime, the middle layer of lake water. Lying below the epilimnion, this water rapidly loses warmth.

Watershed storage area The percentage of a drainage area labeled lacustrine (lakes) and palustrine (wetlands) on U.S. Fish and Wildlife Service National Wetlands Inventory Data.

Zooplankton: The animal portion of the living particles in water that freely float in open water, eat bacteria, algae, detritus and sometimes other

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Appendix B Abbreviations and Units

Abbreviations ALK = Alkalinity mg/L CACO3 TP= total phosphorus in mg/L (decimal) or µg/L as whole number TKN= total Kjeldahl nitrogen in mg/l TN: TP=Total Nitrogen (TKN): Total Phosphorus ratio TSS= total suspended solids in mg/l TSV= total suspended volatile solids in mg/l TSIN= total suspended inorganic solids in mg/l Spec. Cond. = Specific Conductance CL= chloride in mg/l DO= dissolved oxygen in mg/l Temp.= temperature in degrees centigrade Chl-a= chlorophyll-a in µg/l TSI= Carlson's TSI (P=TP, S=Secchi, C=Chla) Pheo= pheophytin in µg/l Obs.= Observations NO2 + NO3 =Nitrate + Nitrite Nitrogen, Total

Units pH= pH in SU mg/L = Milligrams / Liter µg/L = Microgram / Liter µScm = Micro Siemens / Centimeter mV = Millivolts CU = Cobalt units

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Appendix C. 2008 Water Quality Data

Total Collection Depth Phosphorus date site ID (meters) Secchi (ft) (ppb) Chlorophyll-A (ug/L) Sulfate (mg/L) 05/15/08 102 0 7.872 24 6.47 12.6 06/02/08 102 0 7.5 16 3.11 06/23/08 102 0 8.5 17 2.54 07/07/08 102 0 9.5 28 3.64 07/21/08 102 0 10.988 20 5.64 12.4 08/04/08 102 0 12 20 5.9 08/18/08 102 0 8 20 7.1 09/08/08 102 0 6.5 30 10.7 05/16/08 113 0 7.872 15 5.23 9.77 06/02/08 113 0 7.5 15 3.11 06/23/08 113 0 9.5 12 2.36 07/07/08 113 0 8.5 15 4.97 07/22/08 113 0 9.84 21 3.27 9.43 08/04/08 113 0 8 18 4.17 08/18/08 113 0 8 20 4.3 09/03/08 113 0 7.6 30 5.73 05/16/08 116 0 3.5 23 2.22 12.1 06/02/08 116 0 3 23 2.57 <1.00 06/23/08 116 0 2.5 24 1.66 8.68 07/07/08 116 0 3.75 22 2.5 9.43 07/22/08 116 0 4.92 30 3.6 9.64 08/05/08 116 0 3.5 28 3.65 10.4 08/16/08 116 0 4 30 3.2 11.1 09/03/08 116 0 3.5 40 6.57 12 09/30/08 116 0 3.936 35 11.6 05/16/08 130 0 5.904 21 4.89 15.4 06/02/08 130 0 6 20 4.31 14.4 06/23/08 130 0 7.5 16 3.52 14.7 07/07/08 130 0 7 19 4.31 14.6 07/22/08 130 0 7.216 19 11.6 14.6 08/05/08 130 0 6 18 9.63 14.6 08/18/08 130 0 7.5 20 6.2 14.9 09/03/08 130 0 6 30 10.4 14.8 05/15/08 131 0 11.972 19 3.95 6.25 06/02/08 131 0 7.5 30 8.42 5.8 06/23/08 131 0 10 18 2.85 6.4 07/07/08 131 0 10 21 1.5 6.16 07/22/08 131 0 9.184 18 4.15 6.5 08/04/08 131 0 12.5 19 3.85 6.54 08/18/08 131 0 11.5 20 3.9 6.67 09/08/08 131 0 14.5 30 4.9 6.3 05/15/08 132 0 7.872 18 6.14 13.9 06/02/08 132 0 7 20 3.85 6.28 07/07/08 132 0 8.5 15 5.12 13.7 07/21/08 132 0 8.856 19 4.93 13.7 08/04/08 132 0 7.6 21 6.43 13.5

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08/18/08 132 0 5.6 30 8.7 13.6 09/03/08 132 0 5.5 40 12.1 13.4 09/29/08 132 0 7.872 27 12.5 6/23/208 132 0 8.5 13 1.81 14.1 05/15/08 133 0 7.872 28 6.89 06/02/08 133 0 7 25 5.72 6.16 06/23/08 133 0 8.25 16 4.23 6.05 07/07/08 133 0 9 21 4.71 5.88 07/21/08 133 0 9.184 18 3.03 6.28 08/04/08 133 0 13 17 4.38 08/18/08 133 0 11.5 20 3.6 09/08/08 133 0 9.5 30 5.54 05/16/08 134 0 5.904 24 8.61 10.6 06/02/08 134 0 6 26 5.77 06/23/08 134 0 6.5 19 2.98 07/07/08 134 0 11.25 41 4.15 07/22/08 134 0 7.38 20 6.9 14.4 08/05/08 134 0 5.5 23 9.35 08/18/08 134 0 6.5 30 11 09/03/08 134 0 6 30 11.5

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