Little Pine Lake CROW WING COUNTY

Transcription

1 Little Pine Lake CROW WING COUNTY Lake Water Quality Summary Little Pine Lake is located 4 miles northeast of Crosslake, MN in Crow Wing County. It is a mostly oval lake covering 352 acres (Table 1). Little Pine Lake has one inlet and two outlets, which classify it as a drainage lake. Water enters Little Pine Lake from Fox and Eagle Lakes to the north. Water flows west from Little Pine Lake into Daggett Lake, which flows into Cross Lake and eventually the Pine River. Water quality data have been collected on Little Pine Lake from (Tables 2 & 3). These data show that the lake is mesotrophic (TSI = 48) with moderately clear water conditions most of the summer and excellent recreational opportunities. Little Pine Lake is part of the Whitefish Area Property Owners Association. The Whitefish Area Property Owners Association has been active since 197. Their mission statement is "to promote environmental stewardship throughout the Whitefish area and the Pine River Watershed". The Association has been involved in numerous activities including water quality monitoring, education, state regulations, fishing and supporting local business. Table 1. Little Pine Lake location and key physical characteristics. Location Data MN Lake ID: County: Crow Wing Ecoregion: Northern Lakes and Forests Major Drainage Basin: Pine R. Latitude/Longitude: / Invasive Species: Curly-Leaf Pondweed Physical Characteristics Surface area (acres): Littoral area (acres): % Littoral area: 53.8 Max depth (ft), (m): 36., 9.1 Inlets: 1 Outlets: 2 Public Accesses: Table 2. Availability of primary data types for Little Pine Lake. Data Availability Transparency data Good data set from Chemical data Good data set from 23, 25, Inlet/Outlet data Inlet data exist from previous watershed studies. Recommendations For recommendations refer to page 18. RMB Environmental Laboratories, Inc. 1 of Little Pine Lake

2 Lake Map Figure 1. Map of Little Pine Lake with 21 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 Citizen Lake Monitoring Program (CLMP), Pine River Clean Water Partnership (CWP), Whitefish Area Property Owners Association (WAPOA). Lake Site Depth (ft) Monitoring Programs 21 3 CLMP: CLMP: 1984, , ; CWP: CLMP: ; WAPOA: 1975, 1984, , 1998, 24 24*Primary site 36 WAPOA: 22-25, No data RMB Environmental Laboratories, Inc. 2 of Little Pine Lake

3 Average Water Quality Statistics The information below describes available chemical data for Little Pine Lake through 214 (Table 4). Data for total phosphorus, chlorophyll a, and Secchi depth are from the primary site 24. 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. Little Pine Lake is in the Northern Lakes and Forests Ecoregion. 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) > 3 3 Chlorophyll a (ug/l) > 9 Chlorophyll a max (ug/l) 1.8 < 15 Secchi depth (ft) < 6.5 Interpretation Results are within the expected range for the Northern Lakes and Forests Ecoregion. Dissolved oxygen See page 8 Dissolved oxygen depth profiles show that the lake stratifies in summer. Total Kjeldahl Nitrogen (mg/l) NA <.4.75 No data available. Alkalinity (mg/l) NA 4 14 No data available. Color (Pt-Co Units) NA 1 35 No data available. 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) NA No data available. Total Suspended Solids (mg/l) NA <1 2 No data available. Conductivity (umhos/cm) Within the expected range for the ecoregion. TN:TP Ratio NA 25:1-35:1 No data available. 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, ug/l (ppb) RMB Environmental Laboratories, Inc. 3 of Little Pine Lake

4 Water Quality Characteristics - Historical Means and Ranges Table 5. Water quality means and ranges for primary sites. Parameters Primary Site 24 Site 23 Site 22 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 Figure 2. Little 2. Lake Pine insert Lake total total phosphorus, chlorophyll chlorophyll a and and 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 24). xxx). Figure Figure adapted adapted after Moore and Thornton, [Ed.] Lake and Reservoir Restoration Guidance Manual. (Doc. No. EPA 44/5-88-2) after Moore and Thornton, [Ed.] Lake and Reservoir Restoration Guidance Manual. (Doc. No. EPA 44/5-88-2) RMB Environmental Laboratories, Inc. 4 of Little Pine 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 annual mean transparency in Little Pine Lake ranges from 7.8 to 11.9 feet (Figure 3). The annual means hover pretty close to the long-term mean. For trend analysis, see page 1. Transparency monitoring should be continued annually at site 22 in order to track water quality changes. 14 Precipitation Transparency and Precipitation 1 12 Secchi Mean 9 8 Secchi Depth (ft) Precipitation (in) Date Figure 3. Annual mean transparency compared to long-term mean transparency. Little Pine Lake transparency ranges from 4.5 to 11.5 feet at the primary site (24). Figure 4 shows the seasonal transparency dynamics. The maximum Secchi reading is usually obtained in early summer. Little Pine 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 Little Pine Lake

6 Secchi Depth (ft) Seasonal Transparency Dynamics pattern Poly. (pattern) Figure 4. Seasonal transparency dynamics and year to year comparison (Primary Site 23/24). 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. Little Pine Lake was rated as being "not quite crystal clear" 71% of the time by samplers at site 24 between 23 and 211 (Figure 5). 26% 3% Physical Appearance Rating 3% Crystal clear water 71% Not quite crystal clear a little algae visible 26% Definite algae green, yellow, or brown color apparent % High algae levels with limited clarity and/or mild odor apparent 71% % Severely high algae levels Figure 5. Little Pine Lake physical appearance ratings by samplers. RMB Environmental Laboratories, Inc. 6 of Little Pine Lake

7 As the Secchi depth decreases, the perception of recreational suitability of the lake decreases. Little Pine Lake was rated as being "beautiful" 43% of the time from 23 to 211 (Figure 6). 14% Recreational Suitability Rating 43% Beautiful, could not be better 43% 43% Very minor aesthetic problems; excellent for swimming, boating 14% Swimming and aesthetic enjoyment of the lake slightly impaired because of algae levels 43% % Desire to swim and level of enjoyment of the lake substantially reduced because of algae levels % 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 Little Pine Lake is phosphorus limited, which means that algae and aquatic plant growth is dependent upon available phosphorus. Total phosphorus was evaluated in Little Pine Lake in 23, 25, The data do not indicate much seasonal variability. The majority of the data points fall into the eutrophic range (Figure 7). Total Phosphorus (ug/l) Eutrophic Mesotrophic Oligotrophic Total Phosphorus Phosphorus should continue to be monitored to track any future changes in water quality. Figure 7. Historical total phosphorus concentrations (ug/l) for Little Pine Lake site 24. RMB Environmental Laboratories, Inc. 7 of Little Pine 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 29 concentrations greater 4 21 than 1 ug/l are perceived as a mild algae bloom, while Minor Algae concentrations greater than 2 ug/l are perceived as a nuisance. Figure 8. Chlorophyll a concentrations (ug/l) for Little Pine Lake at site 24. Chlorophyll a was evaluated in Little Pine Lake at site 24 in 23, 25, (Figure 8). Chlorophyll a concentrations went above 1 ug/l in some years, indicating minor algae blooms. There was not much variation over the years monitored and chlorophyll a concentrations remained relatively steady over the summer. Dissolved Oxygen Chlorophyll a (ul/l) Chlorophyll a Depth (m) Dissolved Oxygen (mg/l) 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. Little Pine Lake is a moderately deep lake, with a maximum depth of 36 feet. Dissolved oxygen profiles from data collected in 21 show stratification developing mid-summer (Figure 9). The thermocline varies between 5-6 meters ( feet) during the summer, and the oxygen is depleted mid-summer under the thermocline. This means gamefish will be scarce below this depth Figure 9. Dissolved oxygen profile for Little Pine Lake. 11 RMB Environmental Laboratories, Inc. 8 of Little Pine 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 Little Pine Lake falls into the mesotrophic range (Figure 1). There is good agreement between the TSI for phosphorus, chlorophyll a and transparency, indicating that these variables are strongly related (Table 6). Little Pine Lake Table 6. Trophic State Index for site 24. Trophic State Index Site 24 TSI Total Phosphorus 51 TSI Chlorophyll-a 47 TSI Secchi 46 TSI Mean 48 Trophic State: Mesotrophic Numbers represent the mean TSI for each parameter. Hypereutrophic Eutrophic Mesotrophic Oligotrophic Mesotrophic lakes (TSI 4-5) are characterized by moderately clear water most of the summer. "Meso" means middle or mid; therefore, mesotrophic means a medium amount of productivity. Mesotrophic lakes are commonly found in central Minnesota and have clear water with algal blooms in late summer (Table 7). They are also good for walleye fishing. Figure 1. Trophic state index chart with corresponding trophic status. Table 7. Trophic state index attributes and their corresponding fisheries and recreation characteristics. TSI Attributes Fisheries & Recreation <3 Oligotrophy: Clear water, oxygen throughout Trout fisheries dominate the year at the bottom of the lake, very deep cold water. 3-4 Bottom of shallower lakes may become anoxic (no oxygen). Trout fisheries in deep lakes only. Walleye, Cisco present. 4-5 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. 5-6 Eutrophy: Algae and aquatic plant problems possible. "Green" water most of the year. Warm-water fisheries only. Bass may dominate. 6-7 Blue-green algae dominate, algal scums and aquatic plant problems. Dense algae and aquatic plants. Low water clarity may discourage swimming and boating. 7-8 Hypereutrophy: Dense algae and aquatic Water is not suitable for recreation. plants. >8 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 Little Pine Lake

10 Trend Analysis For detecting trends, a minimum of 8-1 years of data with 4 or more readings per season are recommended. Minimum confidence accepted by the MPCA is 9%. This means that there is a 9% chance that the data are showing a true trend and a 1% 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. Little Pine 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 22. Lake Site Parameter Date Range Trend Probability 24 Total Phosphorus 23, 25, Improving 9% 24 Chlorophyll a 23, 25, No trend Transparency No trend Transparency 1984, , 1998, Improving 99% 23 Transparency No trend -- Secchi Depth (ft) Little Pine Lake Transparency Trend 9/4/1984 6/21/1986 8/4/1986 9/25/1986 7/11/1987 8/2/1987 6/18/1988 7/3/1988 9/17/1988 7/1/1989 8/12/1989 6/8/199 7/2/199 9/2/199 6/17/1991 8/3/1991 9/17/1991 9/2/25 6/1/27 9/17/27 7/2/28 6/14/29 5/16/21 7/5/21 9/8/21 7/2/211 9/5/211 8/18/212 8/1/213 7/4/214 Figure 11. Transparency (feet) trend for site 23 from 1984, , Long term trend Short term trend Little Pine Lake shows evidence of a long-term improving trend in water quality since 1984 (Table 8, Figure 11). From , there is no trend in transparency, meaning the water quality is stable over that time period. Monitoring should continue so that trends can be tracked in future years. RMB Environmental Laboratories, Inc. 1 of Little Pine 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. Little Pine Lake is in the Northern Lakes and Forest Ecoregion. The mean total phosphorus, chlorophyll a and transparency (Secchi depth) for Little Pine Lake are within the ecoregion ranges (Figure 13). Figure 12. Minnesota Ecoregions. 6 3 Total Phosphorus (ug/l, ppb) Chlorophyll-a (ug/l, ppb) Secchi depth (ft) increased algae crystal clear NLF Ecoregion Little Pine NLF Little Pine Ecoregion 25 NLF Ecoregion Little Pine Figure 13. Little Pine Lake ranges compared to Northern Lakes and Forest Ecoregion ranges. The Little Pine Lake total phosphorus and chlorophyll a ranges are from 35 data points collected in May-September of 23, 25, The Little Pine Lake Secchi depth range is from 39 data points collected in May- September of RMB Environmental Laboratories, Inc. 11 of Little Pine 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. Little Pine Lake is located in minor watershed 114 (Figure 15). Figure 14. Major Watershed. Figure 15. Minor Watershed. The MN DNR also has evaluated catchments for each individual lake with greater than 1 acres surface area. These lakesheds (catchments) are the building blocks for the larger scale watersheds. Little Pine Lake falls within lakeshed 1144 (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 Little Pine Lake s watershed, containing all the lakesheds upstream of the Little Pine Lake Figure 16. Little Pine Lake lakeshed (1144) with land ownership, lakes, wetlands, and rivers illustrated. RMB Environmental Laboratories, Inc. 12 of Little Pine Lake

13 lakeshed, see page 17. The data interpretation of the Little Pine Lake lakeshed includes only the immediate lakeshed as this area is the land surface that flows directly into Little Pine 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. Little Pine Lake lakeshed vitals table. Lakeshed Vitals Rating Lake Area acres descriptive Littoral Zone Area acres descriptive Lake Max Depth 3 feet descriptive Lake Mean Depth 12.6 feet descriptive Water Residence Time.1 Miles of Stream 4.86 miles descriptive Inlets 1 Outlets 2 Major Watershed 11 - Pine River descriptive Minor Watershed 114 descriptive Lakeshed 1144 descriptive Ecoregion Northern Lakes and Forests descriptive Total Lakeshed to Lake Area Ratio (total lakeshed includes lake area) 9:1 Standard Watershed to Lake Basin Ratio (standard watershed includes lake areas) 25:1 Wetland Coverage (NWI) 9.5% Aquatic Invasive Species Public Drainage Ditches Public Lake Accesses Zebra Mussels Miles of Shoreline 6.98 miles descriptive Shoreline Development Index 2.66 Public Land to Private Land Ratio 1:5.3 Development Classification General Development Miles of Road 7.53 miles descriptive Municipalities in lakeshed Fifty Lakes, Crosslake Possible in County Tax Forfeited lands (brown in Forestry Practices Figure 16). See 215 County Forest Plan: Feedlots 1 Individual Subsurface Sewage Treatment Systems Sewage Management (Inspection and assessment required for all permits and property transfers within the Shoreland Protection Zone) Lake Management Plan None Lake Vegetation Survey/Plan None RMB Environmental Laboratories, Inc. 13 of Little Pine 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. Figure 17. Little Pine Lake lakeshed (1144) land cover (NLCD 211). 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 Little Pine Lake s lakeshed. The National Land Cover Dataset (NLCD) has records from 21 and 211. Table 1 describes Little Pine Lake s lakeshed land cover statistics and percent change from 21 to 211. Overall, there was not much change over this decade. RMB Environmental Laboratories, Inc. 14 of Little Pine Lake

15 Table 1. Little Pine Lake s lakeshed land cover statistics and % change from 21 to 211 (Data Source: NLCD) % Change Land Cover Acres Percent Acres Percent 21 to 211 Cultivated Crops Deciduous Forest Developed, High Intensity Developed, Low Intensity Developed, Medium Intensity Developed, Open Space Emergent Herbaceous Wetlands Evergreen Forest Grassland/Herbaceous Open Water Pasture/Hay Shrub/Scrub Woody Wetlands Total Area Table 11. Little Pine Lake development area and % change from (Data Source: UMN Landsat) Change (acres) Category Acres Percent Acres Percent 199 to 2 Total Impervious Area acres Urban Acreage acres Demographics Little Pine 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 235. Compared to Crow Wing County as a whole, Crosslake City has a higher growth projection (Figure 18). (source: Percent 5% 45% 4% 35% 3% 25% 2% 15% 1% 5% % Population Growth Projection Compared to 21 Population Crosslake City; 21 population = 2283 Crow Wing County; 21 population = 62,5 Ec Dev Region; 21 population = 163, Year Figure 18. Population growth projection for adjacent townships and Crow Wing County. RMB Environmental Laboratories, Inc. 15 of Little Pine 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 Little Pine Lake s lakeshed is forested uplands (Table 12). This land can be the focus of development and protection efforts in the lakeshed. Table 12. Land ownership, land use/land cover, estimated phosphorus loading, and ideas for protection and restoration in the lakeshed (Sources: County parcel data and the 211 National Land Cover Dataset). Private (75.2) 1.4 Public (14.3) 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 13). 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 Little Pine Lake

17 Table 13. 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%. 25-6% n/a Full Restoration > 6% 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. Little Pine Lake s lakeshed is classified with having 25% of the watershed protected and 14.6% 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. Little Pine Lake has many lakesheds upstream, but they are well protected (Figure 2). Percent of the Watershed Protected % 1% 75% Little Pine Lake (25%) Percent of the Watershed with Disturbed Land Cover % 25% 1% Little Pine Lake (14.6%) Figure 19. Little Pine Lake s lakeshed percentage of watershed protected and disturbed. Figure 2. Lakesheds that contribute water to the Little Pine Lake lakeshed. Color-coded based on management focus (Table 13). RMB Environmental Laboratories, Inc. 17 of Little Pine Lake

18 Status of the Fishery (DNR, as of 7/11/25) Little Pine Lake is the easternmost lake in the 14, acre Whitefish chain of lakes in northern Crow Wing County. At 387 acres Little Pine is one of the smaller lakes in the Whitefish chain. Access is from Cross Lake via Daggett Lake. Boating activity can be high with over 1 cabins on Little Pine and over 2 on nearby Daggett Lake. A population survey was conducted on Little Pine Lake in early July 25 to monitor the fish community. Northern pike was the most common fish in gill nets catches while bluegill was the most abundant species in trap nets. The northern pike catch of 14 per gill net was high compared to other similar lakes and has been fairly consistent over the past several surveys. Most northern pike were 19 to 25 inches long; the largest was 32 inches. The cisco (tullibee) gill net catch of 6 per net was high compared to other similar lakes. In previous surveys, the cisco gill net catch was near normal. Most ciscoes were around 9 or 17 inches long. Other species were caught in low numbers (less than 3 per gill net), which is consistent with previous assessments. The three walleyes captured in this survey were all large (21 to 26 inches) and old (11 to 18 years). The walleye catch has been below two per gill net in all surveys since 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 22 and 24 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. Total Phosphorus and chlorophyll a monitoring should continue, as the budget allows, to track trends in water quality. Overall Summary Little Pine Lake is a mesotrophic lake (TSI = 48). It evidence of a long-term improving trend in water quality since 1984 (Table 8, Figure 11). From , there is no trend in transparency, meaning the water quality is stable over that time period. The total phosphorus, chlorophyll a and transparency ranges are within the ecoregion ranges. Fourteen percent (14%) of the Little Pine Lake lakeshed is disturbed by development and agriculture (Figure 19). The threshold of disturbance where water quality tends to decline is 25%. Little Pine Lake is under this threshold. The lakeshed has many land uses that benefit water quality: forest (36%), publicly-owned (14%), and wetlands (21%). Little Pine Lake has a very large watershed to lake area ratio (25:1, Table 9). Much of the watershed is well-protected though, which benefits Little Pine Lake (Figure 2). The shallow depth of the lake makes it susceptible to internal loading, and the phosphorus seasonal pattern indicates that this could be occurring in the lake (Figure 7). In a shallow lake, the water column never completely stratifies (Figure 9). 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. When the surface phosphorus is graphed with the bottom RMB Environmental Laboratories, Inc. 18 of Little Pine Lake

19 phosphorus, internal loading is evident when the bottom phosphorus concentration is higher than the surface (Figure 21). Total Phosphorus (ug/l) Bottom vs Surface Phosphorus in Little Pine Lake Bottom Surface Chlorophyll a 15 concentrations do not show major algae 1 blooms occurring in 5 the lake (Figure 8). Much of the phosphorus coming from internal loading could be getting flushed into Daggett Figure 21. Surface versus bottom phosphorus concentrations in Little Pine Lake. and Cross Lakes. Little Pine Lake has a large amount of water moving through it, which continually flushes the lake. The residence time in the lake is.1 years (Table 9). Priority Impacts to the Lake The priority impacts to Little Pine Lake would be the large watershed and the expansion of residential housing development in the lakeshed and second tier development around the lakeshore. The conversion of small lake cabins to year-round family homes increases the impervious surface and runoff from the lake lots. Most of the private land around the lake has been developed in the first tier, and the second and third tiers are developed in some areas (Figure 16). Once the second and third tiers are developed, it can significantly affect the drainage around the lake. Overall, the development pressure for Little Pine Lake appears high due to its location near the city of Cross Lake. Data from and show there was an increase in development during that period of time (Tables 1-11). The DNR reported during its 25 fisheries survey that boating activity can be high with over 1 cabins on Little Pine and over 2 on nearby Daggett Lake. Best Management Practices Recommendations The management focus for Little Pine Lake should be to protect the current water quality and lakeshed. Efforts should be focused on managing and/or decreasing the impact caused by additional development, including second tier development, and impervious surface area on existing lots (conversion of seasonal cabins to year-round homes). The current lakeshore homeowners can lessen their negative impact on water quality by installing or maintaining the existing tress on their properties. Forested uplands contribute significantly less phosphorus (lbs/acre/year) than developed land cover (Table 12). In addition, filter strips or native vegetative buffers could be installed to decrease or slow the runoff reaching the water s edge. Septic systems should be pumped and inspected regularly. RMB Environmental Laboratories, Inc. 19 of Little Pine 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) Conservation easements Lake Associations Lake condition monitoring Ground truthing visual inspection upstream on stream inlets Watershed runoff mapping by a consultant Shoreline inventory study by a consultant Conservation easements Soil and Water Conservation District (SWCD) and Natural Resources Conservation Service (NRCS) Shoreline restoration Stream buffers Wetland restoration Work with farmers to o Restore wetlands o Implement conservation farming practices o Land retirement programs such as Conservation Reserve Program Organizational contacts and reference sites Whitefish Area Property Owners Association 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 Laurel Street, Suite 14, Brainerd, MN Laurel Street, Suite 13, Brainerd, MN 5641 (218) Minnesota Drive, Brainerd, MN 5641 (218) College Road, Suite 15, Baxter, MN (218) Minnesota Drive, Brainerd, MN 5641 (218) RMB Environmental Laboratories, Inc. 2 of Little Pine Lake