Pelican Lake CROW WING COUNTY

Transcription

1 Pelican Lake CROW WING COUNTY Lake Water Quality Summary Pelican Lake is located six miles east of Pequot Lakes, Minnesota, in Crow Wing County. It covers 8,367 acres, which places it in the upper 5% of lakes in Minnesota in terms of size. Pelican Lake had no inlets until a ditch from Ossawinnamakee was constructed in 1938 to raise the falling levels of the lake. This ditch can be used as an inlet or outlet depending on water levels in both lakes. In the past 10 years, water has not been flowing between the two lakes. Because there are no natural inlets to Pelican Lake, it is classified as a seepage lake. It receives its inflow from precipitation and groundwater. Water quality data have been collected on Pelican Lake since These data show that the lake is oligotrophic (page 9). Oligotrophic lakes are usually found in northern Minnesota and have deep, clear water, rocky and sandy bottoms, and very little algae. The Pelican Lakes Conservation Club (PLCC) is dedicated to the conservation of the environmental resources of the Pelican Lakes and the promotion of the general welfare of the Pelican Lakes area and its population. They have been an active, ongoing body since the late 1940s. The PLCC has been involved in numerous activities including water quality monitoring, education, Healthy Lakes Initiative, managing buoys, fish stocking, improving habitat, recycling and litter cleanup. Table 1. Pelican Lake location and key physical characteristics. Location Data MN Lake ID: County: Crow Wing Ecoregion: Northern Lakes and Forest Major Drainage Basin: Upper Mississippi River Latitude/Longitude: / Invasive Species: Curly-Leaf pondweed Zebra Mussels Physical Characteristics Surface area (acres): 8,367 Littoral area (acres): 3,910 % Littoral area: 47% Max depth (ft), (m): 104 (ft), 31.7 (m) Inlets: 0 Outlets: 1 Public Accesses: 5 Table 2. Availability of primary data types for Pelican Lake. Data Availability Transparency data Chemical data Inlet/Outlet data Excellent data source from , , , , and Excellent data source from , 1984, 1989, , 1996, , and Not available. Recommendations For recommendations refer to page 19. RMB Environmental Laboratories, Inc. 1 of Pelican Lake

2 Lake Map Figure 1. Map of Pelican Lake with 2010 aerial imagery and illustrations of lake depth contour lines, sample site locations, inlets and outlets, and public access points. The light green areas in the lake illustrate the littoral zone, where the sunlight can usually reach the lake bottom, allowing aquatic plants to grow. Table 3. Monitoring programs and associated monitoring sites. Monitoring programs include the Minnesota Pollution Control Agency Lake Monitoring Program (MPCA), Citizen Lake Monitoring Program (CLMP), Assess of Chemicals of Potential Concern in MN Lake Sed and Fish (ACPC), Lake Trend Monitoring (LTM), MN Department of Agriculture Water Quality Monitoring Program (MNDA), National Lake Assessment (NLA), Outdoor Corps Lake Monitoring (OCLM), Pelican Lakes with Pelican Lakes Property Owners Association (PLPOA), Thirty Lakes Watershed District (TLWD). Lake Site Depth (ft) Monitoring Programs ACPC: 2007; LTM: 2005; MNDA: 2007; MPCA: 1991; NLA: 2007; TLWD: 1984, 1989, 1992, 1996, LTM: 2005 CLMP: and 1982 CLMP: and 1982 CLMP: 1983 CLMP: CLMP: ; OCLM: 2004 No data RMB Environmental Laboratories, Inc. 2 of Pelican Lake

3 Average Water Quality Statistics The information below describes available chemical data for Pelican Lake through 2012 (Table 4). All data are from the primary site 101. Minnesota is divided into 7 ecoregions based on land use, vegetation, precipitation and geology. The MPCA has developed a way to determine the "average range" of water quality expected for lakes in each ecoregion. For more information on ecoregions and expected water quality ranges, see page 11. Table 4. Water quality means compared to ecoregion ranges and impaired waters standard. Impaired Parameter Mean Ecoregion Range 1 Waters Standard 2 Total phosphorus (ug/l) > 40 3 Chlorophyll a (ug/l) > 14 Chlorophyll a max (ug/l) 6 < 15 Secchi depth (ft) < 1.4 Dissolved oxygen Total Kjeldahl Nitrogen (mg/l) Dimictic see page 8 Interpretation Results are better than the expected range for the ecoregion. Dissolved oxygen depth profiles show that the deep areas of the lake are anoxic in late summer. 0.4 < Indicates insufficient nitrogen to support summer nitrogeninduced algae blooms. Alkalinity (mg/l) Indicates a low sensitivity to acid rain and a good buffering capacity. Color (Pt-Co Units) Indicates clear water with little to no tannins (brown stain). ph Indicates a hardwater lake. Lake water ph less than 6.5 can affect fish spawning and the solubility of metals in the water. Chloride (mg/l) Above the expected range for the ecoregion, but still considered low level. Total Suspended Solids (mg/l) 1.3 <1 2 Indicates low suspended solids and clear water. Conductivity (umhos/cm) Above the expected range for the ecoregion. Total Nitrogen : Total Phosphorus 40:1 25:1 35:1 Indicates the lake is phosphorus limited, which means that algae growth is limited by the amount of phosphorus in the lake. 1 The ecoregion range is the 25 th -75 th percentile of summer means from ecoregion reference lakes 2 For further information regarding the Impaired Waters Assessment program, refer to 3 Chlorophyll a measurements have been corrected for pheophytin Units: 1 mg/l (ppm) = 1,000 ug/l (ppb) RMB Environmental Laboratories, Inc. 3 of Pelican Lake

4 Water Quality Characteristics - Historical Means and Ranges Table 5. Water quality means and ranges for primary sites. Parameters Primary Site 101 Site 205 Total Phosphorus Mean (ug/l): Total Phosphorus Min: 5 5 Total Phosphorus Max: Number of Observations: 51 5 Chlorophyll a Mean (ug/l): Chlorophyll-a Min: 1 1 Chlorophyll-a Max: 6 5 Number of Observations: 52 5 Secchi Depth Mean (ft): Secchi Depth Min: Secchi Depth Max: Number of Observations: Figure Figure 2. Pelican 2. Lake Lake insert total total phosphorus, phosphorus, chlorophyll chlorophyll a and a and transparency transparency historical historical ranges. ranges. The The arrow arrow represents represents the the range range and and the the black black dot dot represents represents the the historical historical mean mean (Primary (Primary Site Site 101). xxx). Figure Figure adapted adapted after Moore and Thornton, [Ed.] Lake and Reservoir Restoration Guidance Manual. (Doc. No. EPA 440/ ) after Moore and Thornton, [Ed.] Lake and Reservoir Restoration Guidance Manual. (Doc. No. EPA 440/ ) RMB Environmental Laboratories, Inc. 4 of Pelican Lake

5 Transparency (Secchi Depth) Transparency is how easily light can pass through a substance. In lakes it is how deep sunlight penetrates through the water. Plants and algae need sunlight to grow, so they are only able to grow in areas of lakes where the sun penetrates. Water transparency depends on the amount of particles in the water. An increase in particulates results in a decrease in transparency. The transparency varies year to year due to changes in weather, precipitation, lake use, flooding, temperature, lake levels, etc. The mean transparency in Pelican Lake ranges from 12.5 to 22.7 feet at the primary site 101. The transparency throughout the lake appears to be relatively uniform, with the best transparency occurring at site 101. The transparency at site 101 is better than the long-term average in , 2006, 2008, and Site 201 and site 205 appear to have relatively similar patterns of ups and downs, which illustrates seasonal variability. Transparency monitoring should be continued annually at site 101 in order to track water quality changes. 25 Transparency: Annual Means Secchi Depth (ft) Mean 0 Figure 3. Annual mean transparency compared to long-term mean transparency. Pelican Lake transparency ranges from 10 to 26 ft at the primary site (101). Figure 4 shows the seasonal transparency dynamics. The maximum Secchi reading is usually obtained in early summer. Pelican Lake transparency is high in May and June, and then declines through August. The transparency then rebounds in October after fall turnover. This transparency dynamic is typical of a Minnesota lake. The dynamics have to do with algae and zooplankton population dynamics, and lake turnover. It is important for lake residents to understand the seasonal transparency dynamics in their lake so that they are not worried about why their transparency is lower in August than it is in June. It is typical for a lake to vary in transparency throughout the summer. RMB Environmental Laboratories, Inc. 5 of Pelican Lake

6 Secchi Depth (ft) Seasonal Transparency Dynamics Poly. (Pattern) Figure 4. Seasonal transparency dynamics and year to year comparison (Primary Site 205). The black line represents the pattern in the data. User Perceptions When volunteers collect Secchi depth readings, they record their perceptions of the water based on the physical appearance and the recreational suitability. These perceptions can be compared to water quality parameters to see how the lake "user" would experience the lake at that time. Looking at transparency data, as the Secchi depth decreases the perception of the lake's physical appearance rating decreases. Pelican Lake was rated as being "crystal clear" 48% of the time by samplers at site 205 between 1993 and 2007 (Figure 5). 12% 2% Physical Appearance Rating 48% Crystal clear water 38% Not quite crystal clear a little algae visible 38% 48% 12% Definite algae green, yellow, or brown color apparent 2% High algae levels with limited clarity and/or mild odor apparent 0% Severely high algae levels Figure 5. Pelican Lake physical appearance ratings by samplers. RMB Environmental Laboratories, Inc. 6 of Pelican Lake

7 As the Secchi depth decreases, the perception of recreational suitability of the lake decreases. Pelican Lake was rated as being "beautiful" 54% of the time from (Figure 6). 5% 1%1% Recreational Suitability Rating 54% Beautiful, could not be better 39% 54% 39% Very minor aesthetic problems; excellent for swimming, boating 5% Swimming and aesthetic enjoyment of the lake slightly impaired because of algae levels 1% Desire to swim and level of enjoyment of the lake substantially reduced because of algae levels 1% Swimming and aesthetic enjoyment of the lake nearly impossible because of algae levels Figure 6. Recreational suitability rating, as rated by the volunteer monitor. Total Phosphorus Pelican Lake is phosphorus limited, which means that algae and aquatic plant growth is dependent upon available phosphorus. Total phosphorus was evaluated in Pelican Lake in The data do not indicate much seasonal variability. Most of the phosphorus data points are very low level, with just a couple exceptions. The majority of the data points fall into the oligotrophic range (Figure 7). Total Phosphorus (ug/l) Eutrophic 20 Mesotrophic Oligotrophic 0 Total Phosphorus Figure 7. Historical total phosphorus concentrations (ug/l) for Pelican Lake site 101. Phosphorus should continue to be monitored to track any future changes in water quality. RMB Environmental Laboratories, Inc. 7 of Pelican Lake

8 Chlorophyll a Chlorophyll a is the pigment that makes plants and algae green. Chlorophyll a is tested in lakes to determine the algae concentration or how "green" the water is. Chlorophyll a concentrations greater than 10 ug/l are perceived as a mild algae bloom, while concentrations greater than 20 ug/l are perceived as a nuisance. Chlorophyll a (ug/l) Chlorophyll a Chlorophyll a was 2012 evaluated in Pelican Minor Algae Lake at site 101 from (Figure 8). Chlorophyll a Figure 8. Chlorophyll a concentrations (ug/l) for Pelican Lake at site 101. concentrations remained well below 10 ug/l on all sample dates, indicating clear water most of the summer. There was not much variation over the years monitored and chlorophyll a concentrations remained relatively steady over the summer. Dissolved Oxygen Depth (m) Dissolved Oxygen (mg/l) /29/2004 6/26/2004 7/26/2004 8/25/ /22/2004 Dissolved Oxygen (DO) is the amount of oxygen dissolved in lake water. Oxygen is necessary for all living organisms to survive except for some bacteria. Living organisms breathe in oxygen that is dissolved in the water. Dissolved oxygen levels of <5 mg/l are typically avoided by game fisheries. Pelican Lake is a very deep lake, with a maximum depth of 104 ft. Dissolved oxygen profiles from data collected in 2004 at site 205 show stratification developing midsummer. The thermocline occurs at approximately 10 meters (33 feet), which means that gamefish will be scarce below this depth. Figure 9 is a representative DO profile for Pelican Lake and it illustrates stratification in the summer of 2004 at site 205. Figure 9. Dissolved oxygen profile for Pelican Lake site RMB Environmental Laboratories, Inc. 8 of Pelican Lake

9 Trophic State Index (TSI) TSI is a standard measure or means for calculating the trophic status or productivity of a lake. More specifically, it is the total weight of living algae (algae biomass) in a waterbody at a specific location and time. Three variables, chlorophyll a, Secchi depth, and total phosphorus, independently estimate algal biomass. Phosphorus (nutrients), chlorophyll a (algae concentration) and Secchi depth (transparency) are related. As phosphorus increases, there is more food available for algae, resulting in increased algal concentrations. When algal concentrations increase, the water becomes less transparent and the Secchi depth decreases. If all three TSI numbers are within a few points of each other, they are strongly related. If they are different, there are other dynamics influencing the lake s productivity, and TSI mean should not be reported for the lake. The mean TSI for Pelican Lake falls into the oligotrophic range (Figure 10). There is good agreement between the TSI for phosphorus, chlorophyll a and transparency, indicating that these variables are strongly related (Table 6). Pelican Lake Oligotrophic lakes (TSI 0-39) are characteristic of extremely clear water throughout the summer and sandy or rocky shores. They are excellent for recreation. Some very deep oligotrophic lakes are able to support a trout fishery. Table 6. Trophic State Index for site 101. Trophic State Index Site 101 TSI Total Phosphorus 37 TSI Chlorophyll-a 39 TSI Secchi 36 TSI Mean 38 Trophic State: Oligotrophic Numbers represent the mean TSI for each parameter. Hypereutrophic Eutrophic Mesotrophic Oligotrophic Figure 10. Trophic state index chart with corresponding trophic status. 0 Table 7. Trophic state index attributes and their corresponding fisheries and recreation characteristics. TSI Attributes Fisheries & Recreation <30 Oligotrophy: Clear water, oxygen throughout Trout fisheries dominate the year at the bottom of the lake, very deep cold water Bottom of shallower lakes may become anoxic (no oxygen). Trout fisheries in deep lakes only. Walleye, Cisco present Mesotrophy: Water moderately clear most of the summer. May be "greener" in late summer. No oxygen at the bottom of the lake results in loss of trout. Walleye may predominate Eutrophy: Algae and aquatic plant problems possible. "Green" water most of the year. Warm-water fisheries only. Bass may dominate Blue-green algae dominate, algal scums and aquatic plant problems. Dense algae and aquatic plants. Low water clarity may discourage swimming and boating Hypereutrophy: Dense algae and aquatic Water is not suitable for recreation. plants. >80 Algal scums, few aquatic plants Rough fish (carp) dominate; summer fish kills possible Source: Carlson, R.E A trophic state index for lakes. Limnology and Oceanography. 22: RMB Environmental Laboratories, Inc. 9 of Pelican Lake

10 Trend Analysis For detecting trends, a minimum of 8-10 years of data with 4 or more readings per season are recommended. Minimum confidence accepted by the MPCA is 90%. This means that there is a 90% chance that the data are showing a true trend and a 10% chance that the trend is a random result of the data. Only short-term trends can be determined with just a few years of data, because there can be different wet years and dry years, water levels, weather, etc, that affect the water quality naturally. Pelican Lake had enough data to perform a trend analysis on all three parameters (Table 8). The data was analyzed using the Mann Kendall Trend Analysis. Table 8. Trend analysis for site 101. Lake Site Parameter Date Range Trend 101 Total Phosphorus No trend 101 Chlorophyll a No trend 101 Transparency No trend Pelican Lake Transparency Trend Secchi Depth (ft) Figure 11. Transparency (feet) trend for site 101 from Pelican Lake shows no evidence of water quality trends (Figure 11). That means that the water quality is relatively stable. Monitoring of all three parameters should continue so that these trends can be tracked in future years. RMB Environmental Laboratories, Inc. 10 of Pelican Lake

11 Ecoregion Comparisons Minnesota is divided into 7 ecoregions based on land use, vegetation, precipitation and geology (Figure 12). The MPCA has developed a way to determine the "average range" of water quality expected for lakes in each ecoregion. From , the MPCA evaluated the lake water quality for reference lakes. These reference lakes are not considered pristine, but are considered to have little human impact and therefore are representative of the typical lakes within the ecoregion. The "average range" refers to the 25 th - 75 th percentile range for data within each ecoregion. For the purpose of this graphical representation, the means of the reference lake data sets were used. Pelican Lake is in the Northern Lakes and Forest Ecoregion. The mean total phosphorus, chlorophyll a and transparency (Secchi depth) for Pelican Lake are better than the ecoregion ranges (Figure 13). Figure 12. Minnesota Ecoregions Total Phosphorus (ug/l, ppb) Chlorophyll-a (ug/l, ppb) Secchi depth (ft) increased algae crystal clear 0 NLF Ecoregion Pelican 0 NLF Ecoregion Pelican 30 NLF Ecoregion Pelican Lake Figure 13. Pelican Lake ranges compared to Northern Lakes and Forest Ecoregion ranges. The Pelican Lake total phosphorus, chlorophyll a, and secchi depth ranges are from 50 data points collected in May- September of RMB Environmental Laboratories, Inc. 11 of Pelican Lake

12 Lakeshed Data and Interpretations Lakeshed Understanding a lakeshed requires an understanding of basic hydrology. A watershed is defined as all land and water surface area that contribute excess water to a defined point. The MN DNR has delineated three basic scales of watersheds (from large to small): 1) basins, 2) major watersheds, and 3) minor watersheds. The Pine River Major Watershed is one of the watersheds that make up the Upper Mississippi River Basin, which drains south to the Gulf of Mexico (Figure 14). This major watershed is made up of 69 minor watersheds. Pelican Lake is located in minor watershed (Figure 15). Figure 14. Pine River Watershed. Figure 15. Minor Watershed The MN DNR also has evaluated catchments for each individual lake with greater than 100 acres surface area. These lakesheds (catchments) are the building blocks for the larger scale watersheds. Pelican Lake falls within lakeshed (Figure 16). Though very useful for displaying the land and water that contribute directly to a lake, lakesheds are not always true watersheds because they may not show the water flowing into a lake from upstream streams or rivers. While some lakes may have only one or two upstream lakesheds draining into them, others may be connected to a large number of lakesheds, reflecting a larger drainage area via stream or river networks. For further discussion of Pelican Lake s watershed, containing all the lakesheds upstream of the Pelican Lake lakeshed, see page 17. The data interpretation of the Pelican Lake lakeshed Figure 16. Pelican Lake lakeshed ( ) with land ownership, lakes, wetlands, and rivers illustrated. RMB Environmental Laboratories, Inc. 12 of Pelican Lake

13 includes only the immediate lakeshed as this area is the land surface that flows directly into Pelican Lake. The lakeshed vitals table identifies where to focus organizational and management efforts for each lake (Table 9). Criteria were developed using limnological concepts to determine the effect to lake water quality. KEY Possibly detrimental to the lake Warrants attention Beneficial to the lake Table 9. Pelican Lake lakeshed vitals table. Lakeshed Vitals Rating Lake Area acres descriptive Littoral Zone Area acres descriptive Lake Max Depth 104 feet descriptive Lake Mean Depth 22.1 feet Water Residence Time NA NA Miles of Stream 0.47 descriptive Inlets 0 Outlets 0 Major Watershed 11 Pine River descriptive Minor Watershed descriptive Lakeshed descriptive Ecoregion Northern Lakes and Forests descriptive Total Lakeshed to Lake Area Ratio (total lakeshed includes lake area) 1:1 Standard Watershed to Lake Basin Ratio (standard watershed includes lake areas) 2:1 Wetland Coverage (NWI) 2.0% Aquatic Invasive Species Public Drainage Ditches Public Lake Accesses 4 Curly-leaf pondweed, Zebra mussels None Miles of Shoreline 27.2 descriptive Shoreline Development Index 1.99 Public Land to Private Land Ratio 0.08:1 Development Classification General Development Miles of Road descriptive Municipalities in lakeshed Breezy Point County Forest Management: Forestry Practices Feedlots None Individual Subsurface Sewage Treatment Sewage Management Systems (Inspection and assessment required for all permits and property transfers within the Shoreland Protection Zone) Lake Management Plan Healthy Lakes and Rivers, 2006 Lake Vegetation Survey/Plan 2010 RMB Environmental Laboratories, Inc. 13 of Pelican Lake

14 Land Cover / Land Use The activities that occur on the land within the lakeshed can greatly impact a lake. Land use planning helps ensure the use of land resources in an organized fashion so that the needs of the present and future generations can be best addressed. The basic purpose of land use planning is to ensure that each area of land will be used in a manner that provides maximum social benefits without degradation of the land resource. Changes in land use, and ultimately land cover, impact the hydrology of a lakeshed. Land cover is also directly related to the land s ability to absorb and store water rather than cause it to flow overland (gathering nutrients and sediment as it moves) towards the lowest point, typically the lake. Impervious intensity describes the land s inability to absorb water, the higher the % impervious intensity the more area that water cannot penetrate in to the soils. Monitoring the changes in land use can assist in future planning procedures to address the needs of future generations. Phosphorus export, which is the main cause of lake eutrophication, depends on the type of land cover occurring in the lakeshed. Figure 17 depicts the land cover in Pelican Lake s lakeshed. The National Land Cover Dataset has online records of land cover statistics from years 2001 and Although some of this data is 12 years old, it is the most recent data set that is Figure 17. Pelican Lake lakeshed ( ) land cover ( comparable. Table 10 describes Pelican Lake s lakeshed land cover statistics and percent change from 2001 to Due to the many factors that influence demographics, one cannot determine with certainty the projected statistics over the next 10, 20, 30+ years, but one can see the transitions occurring within the last 12 years within the lakeshed. RMB Environmental Laboratories, Inc. 14 of Pelican Lake

15 Table 10. Pelican Lake s lakeshed land cover statistics and % change from 2001 to 2006 ( % Change Land Cover Acres Percent Acres Percent 2001 to 2006 Agriculture % Increase Forest % Decrease Grass/Shrub/Wetland % Increase Water % Decrease Urban % Decrease Impervious Intensity % % Decrease No Change No Change No Change Total Area Total Impervious Area (Percent Impervious Area Excludes Water Area) % Decrease Demographics Pelican Lake is classified as a general development lake. General development lakes usually have more than 225 acres of water per mile of shoreline, 25 dwellings per mile of shoreline, and are more than 15 feet deep. The Minnesota Department of Administration Geographic and Demographic Analysis Division extrapolated future population in 5-year increments out to These projections are shown in Figure 6 below. Compared to Crow Wing County as a whole, Pelican and Mission Townships, and the city of Breezy Point, have higher extrapolated growth projections. In contrast, Lake Edward Township has a slightly lower extrapolated growth projection (Figure 18). Figure 18. Population growth projection for the townships around Pelican Lake, the city of Breezy Point, and Crow Wing County (source: te.mn.us/resource.html?id= Percentage of 2006 Population 110% 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Population Growth Projection Pelican Township; 2006 population: 456 Mission Township; 2006 population: 771 Lake Edward Township; 2006 population: 2,049 City of Breezy Point; 2006 population: 1,642 Crow Wing County; 2006 population: 61, Extrapolation RMB Environmental Laboratories, Inc. 15 of Pelican Lake

16 Lakeshed Water Quality Protection Strategy Each lakeshed has a different makeup of public and private lands. Looking in more detail at the makeup of these lands can give insight on where to focus protection efforts. The protected lands (easements, wetlands, public land) are the future water quality infrastructure for the lake. Developed land and agriculture have the highest phosphorus runoff coefficients, so this land should be minimized for water quality protection. The majority of the land within Pelican Lake s lakeshed is privately owned and composed of forested uplands(table 11). In addition, a large portion of land found within the other category was verified as being forested. This land can be the focus of development and protection efforts in the lakeshed. Table 11. Land ownership, land use/land cover, estimated phosphorus loading, and ideas for protection and restoration in the lakeshed (Sources: Crow Wing County parcel data, National Wetlands Inventory, and the 2006 National Land Cover Dataset). Private (29%) 68% Public (3%) Developed Agriculture Forested Uplands Other Wetlands Open Water County State Federal Land Use (%) Runoff Coefficient Lbs of phosphorus/acre/year Estimated Phosphorus Loading Acreage x runoff coefficient Description Focused on Shoreland Cropland Focus of development and protection efforts Open, pasture, grassland, shrubland Protected Potential Phase 3 Discussion Items Shoreline restoration Restore wetlands; CRP Forest stewardship planning, 3 rd party certification, SFIA, local woodland cooperatives Protected by Wetland Conservation Act County Tax Forfeit Lands State Forest National Forest DNR Fisheries approach for lake protection and restoration Credit: Peter Jacobson and Michael Duval, Minnesota DNR Fisheries In an effort to prioritize protection and restoration efforts of fishery lakes, the MN DNR has developed a ranking system by separating lakes into two categories, those needing protection and those needing restoration. Modeling by the DNR Fisheries Research Unit suggests that total phosphorus concentrations increase significantly over natural concentrations in lakes that have watershed with disturbance greater than 25%. Therefore, lakes with watersheds that have less than 25% disturbance need protection and lakes with more than 25% disturbance need restoration (Table 12). Watershed disturbance was defined as having urban, agricultural and mining land uses. Watershed protection is defined as publicly owned land or conservation easement. RMB Environmental Laboratories, Inc. 16 of Pelican Lake

17 Table 12. Suggested approaches for watershed protection and restoration of DNR-managed fish lakes in Minnesota. Watershed Disturbance (%) Watershed Protected (%) Management Type Comments < 25% > 75% Vigilance < 75% Protection Sufficiently protected -- Water quality supports healthy and diverse native fish communities. Keep public lands protected. Excellent candidates for protection -- Water quality can be maintained in a range that supports healthy and diverse native fish communities. Disturbed lands should be limited to less than 25% % n/a Full Restoration > 60% n/a Partial Restoration Realistic chance for full restoration of water quality and improve quality of fish communities. Disturbed land percentage should be reduced and BMPs implemented. Restoration will be very expensive and probably will not achieve water quality conditions necessary to sustain healthy fish communities. Restoration opportunities must be critically evaluated to assure feasible positive outcomes. The next step was to prioritize lakes within each of these management categories. DNR Fisheries identified high value fishery lakes, such as cisco refuge lakes. Ciscos (Coregonus artedi) can be an early indicator of eutrophication in a lake because they require cold hypolimnetic temperatures and high dissolved oxygen levels. These watersheds with low disturbance and high value fishery lakes are excellent candidates for priority protection measures, especially those that are related to forestry and minimizing the effects of landscape disturbance. Forest stewardship planning, harvest coordination to reduce hydrology impacts and forest conservation easements are some potential tools that can protect these high value resources for the long term. Pelican Lake s lakeshed is classified with having 70.9% of the watershed protected and 4.1% of the watershed disturbed (Figure 19). Therefore, this lakeshed should have a protection focus. Goals for the lake should be to limit any increase in disturbed land use. Figure 20 displays the upstream lakesheds that contribute water to the lakeshed of interest. All of the land and water area in this figure has the potential to contribute water to Pelican Lake, whether through direct overland flow or through a creek or river. There are 14 upstream of the Pelican Lake lakeshed. Percent of the Watershed Protected 0% 75% 100% Pelican Lake (70.9%) Percent of the Watershed with Disturbed Land Cover 0% 25% 100% Pelican Lake (4.1%) Figure 19. Pelican Lake s lakeshed percentage of watershed protected and disturbed. Figure 20. Upstream lakesheds that contribute water to the Pelican Lake lakeshed. Color-coded based on management focus (Table 12). RMB Environmental Laboratories, Inc. 17 of Pelican Lake

18 Status of the Fishery (DNR, as of 08/10/2009) Pelican Lake, at 8,253 acres, is one of the largest and most popular lakes in the Brainerd area. The lake is heavily developed with 22.9 homes/cabins per shoreline mile in Two resorts remain on the lake along with a youth camp. There are four public accesses and a public swimming beach that provide recreational opportunities. The maximum depth is 104 feet and about 47% of the lake is 15 feet deep or less. Shallow water substrates consist primarily of sand, although areas of gravel, rubble, marl and silt are also common. The aquatic plant community is quite diverse, and with 38 species present, is critical to maintaining healthy fish populations. Emergent plants such as bulrush are important for shoreline protection, maintaining water quality and they provide essential spawning habitat for bass and panfish species. Submerged plants provide food and cover needed by fish and other aquatic species. The 2009 walleye catch showed a significant decline and dropped to near the lake's first quartile value for the first time since Young fish remain abundant in fall electrofishing samples however. Fish from years of both fry and fingerling stockings were fairly common in the catch. Average size was 15.8 inches and 1.55 pounds up slightly from their 2006 values. Eleven year classes were sampled with the 2005 and 2006 classes being most abundant in the catch. Northern pike abundance (8.07/GN) rose into the "high" category for the first time in Pike showed a statistically significant increase in abundance over the 2006 catch of 3.93/GN. Fish aged 2-4 comprised 84% of the catch. Size averaged 21 inches and 2.16 pounds compared to 23 inches and 2.99 pounds in Pike at least 24 inches long comprised 13% of the catch, while 3% were at least 30 inches long. Largemouth bass were sampled by electrofishing in spring of The catch rate was 99/hour compared to 122/hr in Bass averaged 11.2 inches long in both samples. Of bass at least 8.0 inches long, 38% were at least 12 inches long, 13% were at least 15 inches long and 2% were at least 18 inches long. The bluegill catch was similar to that of Growth was "average" and 15% were at least 7.0 inches long. The crappie catch was also in the "average" category in both gill and trap nets. For the combined sample, 86% were at least 8.0 inches long and 5% exceeded 12.0 inches. The yellow perch catch (4.53/GN) dropped below the first quartile value for the lake class for the first time in at least ten nettings and exhibited a statistically significant decrease over the 2006 catch of 8.67/GN. Perch had slow growth through about age six. The cisco catch (0.80/GN) remained in the "average" category for the lake class. Cisco growth was "fast" in See the link below for specific information on gillnet surveys, stocking information, and fish consumption guidelines. RMB Environmental Laboratories, Inc. 18 of Pelican Lake

19 Key Findings / Recommendations Monitoring Recommendations Transparency monitoring at sites 101 and 205 should be continued annually. It is important to continue transparency monitoring weekly or at least bimonthly every year to enable year-to-year comparisons and trend analyses. Phosphorus and chlorophyll a monitoring should continue at site 101, as the budget allows, to track future water quality trends. Overall Conclusions Overall, Pelican Lake has excellent water quality, and is in good shape for lakeshed protection. It is an oligotrophic lake (TSI 38) with no trend in transparency over the past decade. Three percent (3%) of the lakeshed is in public ownership, and 71% of the lakeshed is protected, while only 4% of the lakeshed is disturbed (Figure 19). Because there are no natural inlets to Pelican Lake, it is classified as a seepage lake. It receives most of its inflow from precipitation and groundwater flow; therefore, the land practices occurring around the lakeshore such as septic systems and unnatural shorelines, as well as water level have a larger relative impact on water quality than for a lake that has inlets. Ciscos (Coregonus artedi) can be an early indicator of eutrophication in a lake because they require cold hypolimnetic temperatures and high dissolved oxygen levels. Dissolved oxygen profiles for Pelican Lake show that the water column is well oxygenated (Figure 9). The DNR reports that the cisco catch (0.80/GN) remained in the "average" category for the lake class. Cisco growth was "fast" in Priority Impacts to the Lake The management focus for Pelican Lake should be to maintain the current water quality. Pelican Lake is heavily developed with 22.9 homes/cabins per shoreline mile in In many areas it is developed out to the 2 nd and 3 rd tiers (Figure 16). Two resorts remain on the lake along with a youth camp. There are four public accesses and a public swimming beach that provide recreational opportunities. The City of Breezy Point is projected to grow in population by 25% in the next 10 years (Figure 18). The City of Breezy Point sits on the northwest corner of Pelican Lake. It is important to implement good stormwater mitigation practices so that runoff from the impervious surface in the city does not run into Pelican Lake. Best Management Practices Recommendations The management focus for Pelican Lake should be to protect the current water quality and restore the lakeshed. Efforts should be focused on managing and/or decreasing the impact of the impervious surface in the lakeshed. Although it may not be possible to decrease the impervious area in the lakeshed, it is possible to reduce the impact of the impervious surface by retaining stormwater instead of allowing it to runoff into the lake. Project ideas include shoreline restorations on lakeshore property, rain gardens in the city and around the lake, and enforcement of county shoreline ordinances that limit impervious surface. A surface water runoff analysis could pinpoint where rain gardens and restored shorelines would be most effective. This type of analysis could be done by the county or a consultant. RMB Environmental Laboratories, Inc. 19 of Pelican Lake

20 Project Implementation The best management practices above can be implemented by a variety of entities. Some possibilities are listed below. Individual property owners Shoreline restoration Rain gardens Aquatic plant bed protection (only remove a small area for swimming) Lake Associations Lake condition monitoring Ground truthing visual inspection upstream on stream inlets Shoreline inventory study by a consultant Soil and Water Conservation District (SWCD) & Natural Resources Conservation Service (NRCS) Shoreline restoration Stream buffers Work with farmers to o Restore wetlands o Implement conservation farming practices o Land retirement programs such as Conservation Reserve Program County-wide Recommendation In order to better manage the impact of septic systems on lake water quality, it is recommended that the county implement a lake-wide septic inspection program. In a program such as this, the county would focus on one to three lakes a year, pull septic system records on those lakes, and require old systems to be inspected. This program can rotate through the county doing a few lakes each year. Since conversion of small cabins to large lake homes could be a future issue, strengthening county shoreline ordinances such as set-backs, impervious surface limits and shoreline alteration (installation of retaining walls and removing trees) will help to protect water quality.aining walls and removing trees) will help to protect water quality. RMB Environmental Laboratories, Inc. 20 of Pelican Lake

21 Organizational contacts and reference sites Pelican Lakes Conservation Club Crow Wing County Land Services Department Crow Wing Soil and Water Conservation District DNR Fisheries Office Regional Minnesota Pollution Control Agency Office Regional Board of Soil and Water Resources Office PLCC P.O. Box 623, Pequot Lakes, MN (218) Laurel Street, Suite 14, Brainerd, MN Laurel Street, Suite 13, Brainerd, MN (218) Minnesota Drive, Brainerd, MN (218) College Road, Suite 105, Baxter, MN (218) Minnesota Drive, Brainerd, MN (218) RMB Environmental Laboratories, Inc. 21 of Pelican Lake