Lake Emily CROW WING COUNTY

Transcription

1 Lake Emily CROW WING COUNTY Lake Water Quality Summary Lake Emily is located on the eastern edge of the City of Emily, MN in Crow Wing County. It is a shallow lake that covers 720 acres and has a maximum depth of 13 feet (Table 1). Lake Emily has two inlets and one outlet, which classify it as a drainage lake (Figure 1). Water enters Lake Emily from Lake Mary and Dahler Lake. The outlet is the Little Pine River, which flows south to eventually join the Pine River. Water quality data have been collected on Lake Emily since 1982 (Tables 2-3). These data show that the lake is eutrophic, which is characteristic of a shallow lake with abundant plant and algae growth. The Emily Lakes and River Association has been involved in numerous activities including water quality monitoring, promoting boating education and safety, and walleye restocking. Table 1. Location data and physical characteristics for Lake Emily. Location Data Physical Characteristics MN Lake ID: Surface area (acres): 720 County: Crow Wing Littoral area (acres): 720 Ecoregion: Northern Lakes and Forest % Littoral area: 100% Major Drainage Basin: Pine River Watershed Max depth (ft), (m): 13, 3.96 Latitude/Longitude: , Inlets: 2 Invasive Species: None as of 2011 Outlets: 1 Public Accesses: 1 Table 2. Data availability for Lake Emily. Data Availability Transparency data Chemical data Inlet/Outlet data Good amount of data from through the CLMP. Good amount of phosphorus and chlorophyll a data, but not enough for a trend analysis. No inlet or outlet data are available. Recommendations For recommendations refer to page 18. RMB Environmental Laboratories, Inc. 1 of Lake Emily

2 Lake Map Figure 1. Map of Lake Emily with 2010 aerial imagery and illustrations of 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), White Fish Property Owners Association (WAPOA), Outdoor Corps Lake Monitoring (OCLM). Lake Site Depth (ft) Monitoring Programs MPCA: 1982, *primary 10 CLMP: ; WAPOA: CLMP: 1999, ; OCLM: ; WAPOA: 2005, RMB Environmental Laboratories, Inc. 2 of Lake Emily

3 Average Water Quality Statistics The information below describes available chemical data for site (202) of Lake Emily through The data set is limited, and all parameters with the exception of total phosphorus, chlorophyll a and secchi depth, are means for just 2004 data. 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 Waters Standard 2 Ecoregion Parameter Mean Range 1 Interpretation Total phosphorus (ug/l) > 30 Results are poorer than the 3 Chlorophyll a (ug/l) > 9 Chlorophyll a max (ug/l) 32 <15 Secchi depth (ft) < 6.5 Dissolved oxygen Polymictic See page 8 expected range for the ecoregion. The mean phosphorus is over the Impaired Waters Standard as well; however, Lake Emily is not listed as impaired as of Dissolved oxygen depth profiles show that the lake mixes all summer. Total Kjeldahl Nitrogen Indicates insufficient nitrogen to support summer nitrogen-induced (mg/l) algae blooms. Alkalinity (mg/l) Indicates a low sensitivity to acid rain and a good buffering capacity. Color (Pt-Co Units) Indicates cloudy or stained water (tannins) ph Within the expected range for the ecoregion. Lake water ph less than 6.5 can affect fish spawning and the solubility of metals in the water. Chloride (mg/l) Slightly over the ecoregion range, but still considered low level. Total Suspended Solids (mg/l) Specific Conductance (umhos/cm) Total Nitrogen :Total Phosphorus 2.0 <1-2 Indicates low suspended solids and clear water Within the expected range for the ecoregion. 15:1 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 Lake Emily

4 Water Quality Characteristics - Historical Means and Ranges Table 5. Water quality means and ranges for primary sites. Parameters Primary Site 201 Site 202 Site 101 Total Phosphorus Mean (ug/l): Total Phosphorus Min: Total Phosphorus Max: Number of Observations: Chlorophyll a Mean (ug/l): Chlorophyll-a Min: Chlorophyll-a Max: Number of Observations: Secchi Depth Mean (ft): Secchi Depth Min: Secchi Depth Max: Number of Observations: Figure 2. Lake Emily total phosphorus, chlorophyll a and transparency historical ranges. The arrow represents the range and the black dot represents the historical mean (Site 202). Figure adapted after Moore and Thornton, [Ed.] Lake and Reservoir Restoration Guidance Manual. (Doc. No. EPA 440/ ) RMB Environmental Laboratories, Inc. 4 of Lake Emily

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 annual mean transparency ranges from 2.4 to 11.4 feet. The transparency is different between sites 201 and 202. Site 202 consistently has the best transparency. It is located by the inlet, which could be flushing out that area and improving transparency. Transparency monitoring should be continued annually at sites 201 and 202 in order to track water quality changes. 12 Transparency: Annual Means 10 Secchi Depth (ft) Site 201 Site Figure 3. Annual mean transparency comparing sites. Lake Emily transparency ranges from 1.5 to 10.0 feet at the primary site (201). Figure 4 shows that the data do not follow much of a pattern, but there is a lot of year-to-year variability. In 2004 and 2007, the transparency was high all summer, while in transparency was low all summer. 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 Lake Emily

6 Secchi Depth (ft) Seasonal Transparency Dynamics pattern 0 2 May 22 May 11 Jun 1 Jul 21 Jul 10 Aug 30 Aug 19 Sep 9 Oct 29 Oct Poly. (pattern) Figure 4. Seasonal transparency dynamics and year to year comparison (Primary Site 201). 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. Lake Emily was rated as being "not quite crystal clear" 41% of the time from (Figure 5). 9% 14% Physical Appearance Rating 14% Crystal clear water 41% Not quite crystal clear a little algae visible 36% 41% 36% Definite algae green, yellow, or brown color apparent 9% High algae levels with limited clarity and/or mild odor apparent 0% Severely high algae levels Figure 5. Physical appearance rating, as rated by the volunteer monitor ( ). RMB Environmental Laboratories, Inc. 6 of Lake Emily

7 As the secchi depth decreases, the perception of recreational suitability of the lake decreases. Lake Emily was rated as having "very minor aesthetic problems" 35% of the time from (Figure 6). 18% 13% Recreational Suitability Rating 13% Beautiful, could not be better 35% Very minor aesthetic problems; excellent for swimming, boating 34% Swimming and aesthetic enjoyment of the lake slightly impaired because of algae levels 34% 35% 18% Desire to swim and level of enjoyment of the lake substantially reduced because of algae levels 0% 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 Lake Emily is phosphorus limited, which means that algae and aquatic plant growth is dependent upon available phosphorus. Total phosphorus was evaluated in Lake Emily in , The data do not indicate much seasonal variability. Sites 101 and 202 have similar concentrations, but site 201 s concentration was much higher (Figure 7). It is not clear whether it is the site that caused the high phosphorus or just the conditions that year started out as a very wet year, which could have contributed to more runoff into the lake. Total Phosphorus (ug/l) Eutrophic Mesotrophic 0 Oligotrophic Total Phosphorus Site 101, 2004 Site 201, 2010 Site 202, 2003 Site 202, 2004 Site 202, 2005 Site 202, 2007 Site 202, 2008 Site 202, 2009 Figure 7. Historical total phosphorus concentrations (ug/l) for Lake Emily. The majority of the data points fall into the eutrophic range. Phosphorus should continue to be monitored to track any future changes in water quality. RMB Environmental Laboratories, Inc. 7 of Lake Emily

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 Site 101, 2004 Site 201, 2010 Site 202, 2003 Site 202, 2004 Site 202, 2005 Site 202, 2007 Site 202, 2008 Chlorophyll a was evaluated in Site 202, 2009 Lake Emily in , Chlorophyll a Minor Algae concentrations reached 10 ug/l in 0 Nuisance Algae 2003, 2005, 2008 and 2010, indicating minor algae blooms (Figure 8). Chlorophyll a concentrations exceeded 20 ug/l Figure 8. Chlorophyll a concentrations (ug/l) for Lake Emily. in 2003, indicating nuisance algae blooms. There was not much variation between sites over the years monitored, and chlorophyll a concentrations remained relatively steady over the summer. Dissolved Oxygen Depth (m) Dissolved Oxygen (mg/l) /27/2004 6/25/2004 7/24/ /25/ /8/2004 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. Lake Emily is a shallow lake, with a maximum depth of 13 ft. Dissolved oxygen profiles from indicate that the lake mixes throughout the summer (Figure 9). In a shallow lake, the water column never completely stratifies. Any windy day can mix up the water column causing phosphorus from the anoxic lake bottom to re-suspend into the water. This phenomenon is known as internal loading. 2 3 Figure 9. Dissolved oxygen profile for Lake Emily in RMB Environmental Laboratories, Inc. 8 of Lake Emily

9 Trophic State Index 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. The results from these three measurements cover different units and ranges and thus cannot be directly compared to each other or averaged. In order to standardize these three measurements to make them directly comparable, we convert them to a trophic state index (TSI). The mean TSI for Lake Emily falls into the eutrophic 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). Lake Emily Eutrophic lakes (TSI 50-70) are characteristic of "green" water most of the summer (Table 7). "Eu" means true and the root "trophy" means nutrients therefore, eutrophic literally means true nutrients or truly nutrient rich (phosphorus). Eutrophic lakes are usually shallow, and are found where the soils are fertile. Eutrophic lakes usually have abundant aquatic plants and algae. Table 6. Trophic State Index for Lake Emily. Trophic State Index Site 202 TSI Total Phosphorus 57 TSI Chlorophyll-a 50 TSI Secchi 53 TSI Mean 53 Trophic State: Eutrophic 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 categories and corresponding lake conditions. 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 Lake Emily

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. There is not enough historical data to perform trend analysis for total phosphorus or chlorophyll a on Lake Emily. Sites 201, and 202 had at least 8 years of transparency data, which was enough data to perform a long-term trend analysis (Table 8). The data was analyzed using the Mann Kendall Trend Analysis. Table 8. Trend analysis for Lake Emily. Lake Site Parameter Date Range Trend Probability 202 Transparency , Decreasing 90% 201 Transparency Decreasing 80% 202 Total Phosphorus , Insufficient data Chlorophyll a , Insufficient data Transparency Trend for Emily Lake Figure 11. Transparency (ft) trend for site 205 from Sites 201 and 202 show a significant declining trend in transparency in the last decade (Figure 11). Over this time, the transparency decreased approximately 2.5 feet per decade. Transparency monitoring should continue at both sites so that this trend can be tracked in future years. RMB Environmental Laboratories, Inc. 10 of Lake Emily

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. Emily Lake is in the Northern Lakes and Forests Ecoregion. The mean total phosphorus, chlorophyll a and transparency (Secchi depth) for Emily are poorer than the expected ecoregion ranges (Fig 13). This could be due to the shallow nature of the lake. Figure 12. Map of Minnesota with the seven ecoregions Total Phosphorus (ug/l, ppb) Chlorophyll-a (ug/l, ppb) Secchi depth (ft) increased algae crystal clear 0 NLF Ecoregion Emily 0 NLF Ecoregion Emily 25 NLF Ecoregion Emily Figures 13a-c. Lake Emily ranges compared to Northern Lakes and Forest Ecoregion ranges. The Lake Emily total phosphorus and chlorophyll a ranges are from 29 data points collected in May-September of , The Lake Emily Secchi depth range is from 38 data points collected in May-September from , RMB Environmental Laboratories, Inc. 11 of Lake Emily

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. Lake Emily is located in minor watershed (Figure 15). Figure 14. Pine River Major Watershed. Figure 15. Minor Watershed contributes water to Lake Emily. 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. Lake Emily falls within lakeshed (Figure 16). Though very useful for displaying the land and water that contribute directly to a lake, lakesheds are not true watersheds because they do 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 Lake Emily s full watershed, containing all the upstream lakesheds, see page 17. The data interpretation of the Lake Emily lakeshed Figure 16. The Lake Emily Lakeshed ( ). This area is the land and water surface that flow directly into Lake Emily. RMB Environmental Laboratories, Inc. 12 of Lake Emily

13 includes only the immediate lakeshed, as this area is the land surface that flows directly into Lake Emily. 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. Lake Emily lakeshed vitals table. Lakeshed Vitals Rating Lake Area 720 acres descriptive Littoral Zone Area 720 acres descriptive Lake Max Depth 13 ft. descriptive Lake Mean Depth 8 ft. Water Residence Time NA NA Miles of Stream 0.7 descriptive Inlets 2 Outlets 1 Major Watershed 11 Pine River descriptive Minor Watershed descriptive Lakeshed descriptive Ecoregion Northern Lakes and Forest descriptive Total Lakeshed to Lake Area Ratio (total lakeshed includes lake area) 2:1 Standard Watershed to Lake Basin Ratio (standard watershed includes lake areas) 59:1 Wetland Coverage 9% Aquatic Invasive Species Public Drainage Ditches Public Lake Accesses 1 None None Miles of Shoreline 4.8 descriptive Shoreline Development Index 1.3 Public Land to Private Land Ratio 0.46:1 Development Classification General Development Miles of Road 9.0 descriptive Municipalities in lakeshed Forestry Practices Feedlots Sewage Management Lake Management Plan Lake Vegetation Survey/Plan Emily County Forest Management: None Individual Subsurface Sewage Treatment Systems (Inspection and assessment required for all permits and property transfers within the Shoreland Protection Zone) Healthy Lakes & Rivers Partnership program, 2004 None RMB Environmental Laboratories, Inc. 13 of Lake Emily

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 lands 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. Figure 17. The Emily ( ) lakeshed land cover ( Impervious intensity describes the lands 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 Lake Emily s lakeshed. The University of Minnesota has online records of land cover statistics from years 1990 and 2000 ( Although this data is 11 years old, it is the only data set available to compare over a decade of time. Table 10 describes Lake Emily s lakeshed land cover statistics and percent change from 1990 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 transition within the lakeshed from agriculture, grass/shrub/wetland, and water acreages to forest and urban acreages. The largest change in percentage is the decrease in agriculture cover (58%). In addition, the impervious intensity has increased, which has implications for storm water runoff into the lake. The increase in impervious intensity is consistent with the increase in urban acreage. RMB Environmental Laboratories, Inc. 14 of Lake Emily

15 Table 10. Lake Emily s lakeshed land cover statistics and % change from 1990 to 2000 ( % Change Land Cover Acres Percent Acres Percent 1990 to 2000 Agriculture % Decrease Grass/Shrub/Wetland % Increase Forest % Increase Water % Decrease Urban % Increase Impervious Intensity % % Decrease % Decrease % Decrease % Increase % Decrease No Change % Increase Total Area Total Impervious Area (Percent Impervious Area Excludes Water Area) % Increase Demographics Lake Emily is classified as a general development lake. General Development Lakes usually have more than 225 acres of water per mile of shoreline and 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 Compared to Crow Wing County as a whole, Fairfield Lake Township has a lower extrapolated growth projection. However, the City of Emily has a higher extrapolated growth projection (Figure 18). Figure 18. Population growth projection for Fairfield Township and Crow Wing County. (source: state.mn.us/resource.ht ml?id=19332) RMB Environmental Laboratories, Inc. 15 of Lake Emily

16 Lake Emily 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 Lake Emily s lakeshed is made up of private forested uplands (Table 11). 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 (37%) 43% Public (20%) Developed Agriculture Forested Uplands Other Wetlands Open Water County State Federal Land Use (%) 3.2% 2.1% 18% 9.8% 4% 42% 4.4% 15.6% 0% 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 Lake Emily

17 Table 12. Suggested approaches for watershed protection and restoration of DNR-managed fish lakes in Minnesota. Watershed Watershed Management Disturbance Protected Comments Type (%) (%) Sufficiently protected -- Water quality supports healthy and > 75% Vigilance diverse native fish communities. Keep public lands protected. < 25% < 75% Protection 25-60% n/a Full Restoration > 60% n/a Partial Restoration 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%. 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. Lake Emily is classified with having 58.3% of the watershed protected and 8.5% of the watershed disturbed (Figure 19). Therefore, Lake Emily 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 Lake Emily, whether through direct overland flow or through a creek or river. Seven of the 12 upstream lakesheds have the same management focus (protection). Percent of the Watershed Protected 0% 75% 100% Lake Emily (58.3%) Percent of the Watershed with Disturbed Land Cover 0% 25% 100% Lake Emily (8.5%) Figure 19. Lake Emily lakeshed s percentage of watershed protected and disturbed. Figure 20. Upstream lakesheds that contribute water to the Emily Lakeshed. Color-coded based on management focus (Table 12). RMB Environmental Laboratories, Inc. 17 of Lake Emily

18 Emily, Status of the Fishery (as of 06/26/2006) Walleyes have been stocked into Lake Emily since 1911, with regular walleye fry stocking beginning in The walleye catch rate was average in 2006 when compared to similar lakes (3.3/gill net). Average size was 19.5" and 2.7 lbs. All of the fish were over 12". The northern pike catch rate was below average (3.3/gill net), although low catch rates have been common in Emily. Average size was 22.2" and 2.6 lbs., with 35% of the fish being 24" or larger. Largemouth bass were captured at the rate of 54.5/hr run-time during spring electrofishing. Average length of was 8.7" and only 8% were 12" or larger. The black crappie catch rate was above average in gill nets (10.0/gill net), with an average length of 7.4". The catch rate was average in trap nets (3.3/trap net), with an average length of 6.9". When both net types were combined, 32% of the fish were 8" or larger. The bluegill catch rate was average (13.9/trap net). Average length was 6.2" and 34% of the fish were 7" or larger. The yellow perch catch rate was well above average (78.9/gill net). Average length was 6.4" and only 3% were 8" or larger. Although most of these fish are not a good size for angling, they provide an important food base for the walleyes and northern pike in this lake. Other fish species captured included black bullhead, bowfin, brown bullhead, hybrid sunfish, pumpkinseed, rock bass, white sucker, and yellow bullhead. See the link below for specific information on gillnet surveys, stocking information, and fish consumption guidelines. Key Findings / Recommendations Monitoring Recommendations Transparency monitoring at sites 201 and 202 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, as the budget allows, to track future water quality trends. Site 201 should be the primary site for Lake Emily. All future phosphorus and chlorophyll a data should be collected at site 201. Data have been collected on both 201 and 202 in the past. Either the water quality in this lake varies greatly year-to-year, or the data is not of sufficient quality to explain the lake dynamics. Overall Conclusions Overall, Lake Emily has fair quality, but it is in fairly good shape for lakeshed protection. It is a shallow, eutrophic lake (TSI=53) with a declining trend in transparency over the past decade. Twenty percent (20%) of the lakeshed is in public ownership, and 58% of the watershed is protected, while only 8% of the watershed is disturbed (Figure 19). RMB Environmental Laboratories, Inc. 18 of Lake Emily

19 There are State Wildlife Management Areas along the east shore, while the City of Emily sits on the northwest shore. Priority Impacts to the Lake There are two priority impacts to Lake Emily. The first is the surrounding development and any future development. The City of Emily sits on the northwest shore, which contributes to a lot of impervious surface (Figure 16). The City of Emily is expected to grow approximately 15% in the next 10 years (Figure 18). In addition, the inlet to Lake Emily on the north shore is developed along the river on both sides. Runoff into the river will flow into Lake Emily. Because Lake Emily is a shallow lake, it is very important to protect native aquatic plant beds to preserve fish habitat and water clarity. In addition, because Lake Emily is a shallow lake, it could be subject to internal loading. Internal loading is when the phosphorus that is in the lake sediment re-suspends into the water column, feeding algae and plants. Phosphorus re-suspends when large boat motors churn up the sediment, and when the lake has a few calm days which allows it to loosely stratify, and then windy days, which mixes the water back up. Best Management Practices Recommendations The management focus for Lake Emily should be to restore the water quality. Restoration efforts should be focused on managing and/or decreasing the impact caused by additional development, and impervious surface area. Project ideas include protecting land with conservation easements, enforcing county shoreline ordinances, smart development, shoreline restoration, rain gardens, and septic system maintenance. Projects that would have the best chance of improving the water quality of Emily include runoff and sedimentation reduction in the City of Emily area and buffer strips along the inlets to the lake. 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 streams. Native aquatic plants stabilize the lake s sediments and tie up phosphorus in their tissues. When aquatic plants are uprooted from a shallow lake, the lake bottom is disturbed, and the phosphorus in the water column gets used by algae instead of plants. This contributes to greener water and more algae blooms. Protecting native aquatic plant beds will ensure a healthy lake and healthy fishery. If the majority of the phosphorus in the lake is coming from internal loading, an alum treatment could be applied to hold the phosphorus in the sediments and prevent its re-suspension into the water column. Future Studies Future studies that would better pinpoint the impacts on the lake include a shoreline inventory, monitoring for internal loading, and a watershed flow analysis. The shoreline inventory would consist of boating around the lake and rating each parcel as to how much of the frontage has a vegetative buffer. This could be done upstream in the inlet as well. Monitoring for internal loading involves collecting hypolimnion water samples (water samples taken 1 foot above the lake s bottom) and corresponding dissolved oxygen profiles. A watershed flow analysis would be done using GIS software to see the areas of heaviest runoff into the lake. This analysis would also help pinpoint whether the City of Emily is the major impact to the lake or not. RMB Environmental Laboratories, Inc. 19 of Lake Emily

20 Organizational contacts and reference sites Emily Lakes & River Association DNR Fisheries Office Regional Minnesota Pollution Control Agency Office Crow Wing Soil and Water Conservation District Crow Wing County Environmental Services Department Minnesota Drive, Brainerd, MN College Road, Suite 105, Baxter, MN , Crow Wing County Land Services Building 322 Laurel St. Suite 13, Brainerd, MN Crow Wing County Land Services Building 322 Laurel St. Suite 14, Brainerd, MN Funding This project was funded in part by the Board of Water & Soil Resources and the Initiative Foundation, a regional foundation. RMB Environmental Laboratories, Inc. 20 of Lake Emily