Round Lake CROW WING COUNTY

Transcription

1 Round Lake CROW WING COUNTY Lake Water Quality Summary Round Lake is located 5 miles north of Brainerd, MN in Crow Wing County. It has a rounded shape, as the name implies, and covers 1,650 acres. Round Lake has two inlets and one outlet, which classifies it as a drainage lake. Sugar Bush Creek flows into Round Lake on the eastern side from North Long Lake. Water also flows into the lake from a wetland on the west side, by Mission Road. Bishops Creek exits Round Lake to the west and flows into Gull Lake. The Gull River flows out of the south end of Gull Lake, and continues south to the Crow Wing River. The Crow Wing River then eventually joins the Mississippi River. Water quality data have been collected on Round Lake since These data show that the lake is on the mesotrophic/eutrophic border (page 9). Lakes on the mesotrophic to eutrophic border are characterized by moderately clear water most of the summer, with possible algae blooms in late summer (Table 7). The Round Lake Improvement Association has been involved in numerous activities including water quality monitoring, education, vegetation planning, Healthy Lakes Initiative, and water level management. Round Lake also has an Improvement District, which is a taxing entity. Table 1. Round 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): Littoral area (acres): 627 % Littoral area: 38% Max depth (ft), (m): 51 (ft), 15.5 (m) Inlets: 2 Outlets: 1 Public Accesses: 1 Table 2. Availability of primary data types for Round Lake. Data Availability Transparency data Excellent data source from , Chemical data Inlet/Outlet data Limited data source from , 1997, 06-07, 10. Not available. Recommendations For recommendations refer to page 18. RMB Environmental Laboratories, Inc. 1 of 13 Round Lake

2 Lake Map Figure 1. Map of Round Lake with 10 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), RMB Environmental Laboratories Lakes Program (RMBEL), and Clean Water Legacy Surface Water Monitoring (CWL). Lake Site Depth (ft) Monitoring Programs * Primary site MPCA: 1997 MPCA: , 1997 CLMP: 1993, CLMP: 1993, CLMP: 1993, MPCA: , 1997; CLMP:1993, , CLMP: , 01-06, CLMP: RMBEL: RMBEL: RMBEL: RMBEL: CWL: 10 RMB Environmental Laboratories, Inc. 2 of 13 Round Lake

3 Average Water Quality Statistics The information below describes available chemical data for Round Lake at site 211 for May- September in 10 (Table 4). 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) > 30 3 Chlorophyll a (ug/l) > 9 Chlorophyll a max (ug/l) 24.3 < 15 Secchi depth (ft) < 6.5 Interpretation Total phosphorus and secchi depth results are within the expected range for the ecoregion. Dissolved oxygen Total Kjeldahl Nitrogen (mg/l) Dimictic see page 8 Dissolved oxygen depth profiles show that the deep areas of the lake are anoxic in late summer 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 Slightly above 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) Above the expected range for the ecoregion, which could be from Highway 371. Total Suspended Solids (mg/l) 3.36 <1 2 Slightly above the expected ecoregion range. Conductivity (umhos/cm) Within the expected range for the ecoregion. Total Nitrogen : Total Phosphorus 38:1 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 13 Round Lake

4 Water Quality Characteristics - Historical Means and Ranges Table 5. Water quality means and ranges for primary sites. Parameters Primary Site 211 Site 2 Site 3 Total Phosphorus Mean (ug/l): Total Phosphorus Min: Total Phosphorus Max: Number of Observations: 5 6 Chlorophyll a Mean (ug/l): Chlorophyll-a Min: Chlorophyll-a Max: Number of Observations: 5 6 Secchi Depth Mean (ft): Secchi Depth Min: Secchi Depth Max: Number of Observations: Site 4 Site 5 Site 6 Figure Figure 2. Round 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 211). 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 13 Round 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 Round Lake ranges from 6.9 to 13.9 feet (Table 5). The transparency throughout the lake appears to be relatively uniform since 1985, with the best transparency occurring at site 3. Site 3 in the southern part of the lake consistently has better transparency than any other site on Round Lake (Figure 3). Transparency is generally greater at deeper areas of lakes where surface water is constantly mixing. Transparency monitoring should be continued annually at the primary site 211 in order to track water quality changes. Sites 2, 3, and 6 have been consistently monitored by volunteers for more than 10 years. Monitoring could continue at these sites if the citizen lake monitors want to stay active in the MPCA s program. Secchi Depth (ft) Transparency Annual Means 211 (Primary) Mean 0 Year Figure 3. Annual mean transparency compared to long-term mean transparency. Round Lake transparency ranges from 4.6 to 18 ft at the primary site (211). Figure 4 shows the seasonal transparency dynamics. The maximum Secchi reading is usually obtained in early summer. Round 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 13 Round Lake

6 Secchi Depth (ft) Seasonal Transparency Trends Poly. (Mean) Date Figure 4. Seasonal transparency dynamics and year to year comparison (Primary Site 211 and site 4). Due to insignificant data for primary site 211, site 4 is included. In the event that secchi readings were taken at both sites on the same day the average are graphed. 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. Round Lake was rated as having "definite algae" 58% of the time by samplers at site 2 in 1993 and between (Figure 5). 10% 5% Physical Appearance Rating 27% 6% Crystal clear water 93% Not quite crystal clear a little algae visible 1% Definite algae green, yellow, or brown color apparent 58% 0% High algae levels with limited clarity and/or mild odor apparent 0% Severely high algae levels Figure 5. Round Lake physical appearance ratings by samplers. RMB Environmental Laboratories, Inc. 6 of 13 Round Lake

7 As the Secchi depth decreases, the perception of recreational suitability of the lake decreases. Round Lake was rated as being "slightly impaired" 49% of the time in 1993 and between (Figure 6). Recreational Suitability Rating 9% 6% 6% Beautiful, could not be better 49% 36% 36% Very minor aesthetic problems; excellent for swimming, boating 49% Swimming and aesthetic enjoyment of the lake slightly impaired because of algae levels 9% 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 Round Lake is phosphorus limited, which means that algae and aquatic plant growth is dependent upon available phosphorus. Total phosphorus was evaluated in Round Lake in and 1997 at site 4 and in 10 at site 211. The data points in 1985 and 1986, though few, are higher than those collected in 1997 and 10 during similar dates. Recent data (1997 and 10) show high total phosphorus readings in late summer and fall, which could be due to fall turnover. Overall, the majority of the data points fall into the mesotrophic 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. Site 4, 1985 Site 4, 1986 Site 4, 1997 Site 211, 10 Figure 7. Historical total phosphorus concentrations (ug/l) for Round Lake sites 4 and 211. RMB Environmental Laboratories, Inc. 7 of 13 Round Lake

8 Chlorophyll a Chlorophyll a is the pigment that makes plants and algae green. Chlorophyll a is tested in lakes to deter mine 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 ug/l are perceived as a nuisance. Chlorophyll a was evaluated in Round Lake in and 1997 at site 4 and in 10 at site 211. (Figure 8). Chlorophyll a concentrations remained below 10 ug/l on all Total Phosphorus (ug/l) Chlorophyll a Minor Algae Nuisance Algae Figure 8. Chlorophyll a concentrations (ug/l) for Round Lake at sites 4 and 211. sample dates at site 4, indicating clear water most of the summer. In 10 at site 211 chlorophyll a increased beyond 10 ug/l on one sample date and above ug/l on one sample date. These dates indicate a minor algae bloom (10 ug/l) and a nuisance algae bloom ( ug/l). Due to a lack of data there is not much variation over the years. Chlorophyll a concentrations remained relatively steady over the summer and should continue to be monitored in order to gain a better data set for future studies. Dissolved Oxygen Depth (m) Dissolved Oxygen (mg/l) /19/10 6/21/10 7/28/10 8/17/10 9/14/10 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. Round Lake is a relatively deep lake, with a maximum depth of 51 ft. Dissolved oxygen profiles from data collected in 10 at site 211 show stratification developing mid-summer. The thermocline occurs between 7 and 10 meters (23-33 feet), which means that gamefish will be scarce below this depth. Figure 9 is a representative DO profile for Round Lake and it illustrates stratification in the summer of 10 at site 211. Figure 9. Dissolved oxygen profile for Round Lake site 211. RMB Environmental Laboratories, Inc. 8 of 13 Round 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. Round Lake The mean TSI for Round Lake falls on the border between mesotrophic and eutrophic (49-51) (Figure 10). There is not good agreement between the different TSI values (Table 6). This difference could be due to the lack of chlorophyll a data, zooplankton grazers selectively eliminating the smaller algal cells, or a loss of rooted vegetation. Lakes on the mesotrophic to eutrophic border (TSI 49-51) are characterized by moderately clear water most of the summer (Table 7). If the water quality becomes more eutrophic the water will start to have extended periods of green water. Table 6. Trophic State Index for site 211. Trophic State Index Site 211 TSI Total Phosphorus 50 TSI Chlorophyll-a 55 TSI Secchi 45 TSI Mean 50 Trophic State: Mesotrophic 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 13 Round 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. Round Lake had enough data to perform a trend analysis using transparency data from (Table 8). Sites 2 and 3 have the longest and most consistent data set of transparency readings. The data was analyzed using the Mann Kendall Trend Analysis. Chlorophyll a and total phosphorus was sampled in 1985, 1986, 1997, 06, and 07 across seven different sites. There is not enough consistent data to run a trend analysis on these parameters. Table 8. Trend analysis for site 3. Lake Site Parameter Date Range Trend 3 Transparency No trend All Sites Chlorophyll a -- Insufficient data All Sites Total Phosphorus -- Insufficient data 25 Round Lake Transparency Trend Secchi Depth (ft) Date Figure 11. Transparency (feet) trend for site 3 from Round Lake shows no evidence of water quality trend for transparency at sites 2 or 3 (Figure 11). That means that the water quality is stable. Transparency monitoring should continue so that this trend can be tracked in future years. RMB Environmental Laboratories, Inc. 10 of 13 Round 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. Round Lake is in the Northern Lakes and Forest Ecoregion. The mean total phosphorus chlorophyll a and Secchi disk values for Round Lake are within or slightly worse 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 Round 0 NLF Ecoregion Round 25 CHF Ecoregion Round Lake Figure 13. Round Lake ranges compared to Northern Lakes and Forest Ecoregion ranges. The Round Lake total phosphorus and chlorophyll a ranges are from 5 data points collected in May-September of 10. The Round Lake Secchi depth range is from 5 data points collected in May-September of 10. RMB Environmental Laboratories, Inc. 11 of 13 Round 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 Crow Wing 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 136 minor watersheds. Round Lake is located in minor watershed (Figure 15). Figure 14. Crow Wing 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. Round 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, Figure 16. Round Lake lakeshed ( ) with land ownership, lakes, wetlands, and rivers illustrated. reflecting a larger drainage area via stream or river networks. For further discussion of Round Lake s watershed, containing all the lakesheds upstream of the Round Lake lakeshed, see page RMB Environmental Laboratories, Inc. 12 of 13 Round Lake

13 17. The data interpretation of the Round Lake lakeshed includes only the immediate lakeshed as this area is the land surface that flows directly into Round 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. Round Lake lakeshed vitals table. Lakeshed Vitals Rating Lake Area acres descriptive Littoral Zone Area acres descriptive Lake Max Depth 51 feet descriptive Lake Mean Depth 18.5 feet Water Residence Time NA NA Miles of Stream 1.80 descriptive Inlets 2 Outlets 1 Major Watershed 12 Crow Wing River descriptive Minor Watershed descriptive Lakeshed descriptive Ecoregion Northern Lakes and Forests 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) 15:1 Wetland Coverage (NWI) 8.6% Aquatic Invasive Species Public Drainage Ditches Public Lake Accesses 1 Zebra Mussels, curly-leaf pondweed None Miles of Shoreline 6.61 descriptive Shoreline Development Index 1.16 Public Land to Private Land Ratio 0.04:1 Development Classification General Development Miles of Road descriptive Municipalities in lakeshed Nisswa 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 01 Lake Vegetation Survey/Plan 06 RMB Environmental Laboratories, Inc. 13 of 13 Round 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 Round Lake s lakeshed. The National Land Cover Dataset has online records of land cover statistics Figure 17. Round Lake lakeshed ( ) land cover ( from years 01 and 06. Although some of this data is 12 years old, it is the most recent data set that is comparable. Table 10 describes Bay Lake s lakeshed land cover statistics and percent change from 01 to 06. Due to the many factors that influence demographics, one cannot determine with certainty the projected statistics over the next 10,, 30+ years, but one can see the transitions occurring within the last 12 years within the lakeshed. RMB Environmental Laboratories, Inc. 14 of 13 Round Lake

15 Table 10. Round Lake s lakeshed land cover statistics and % change from 01 to 06 ( % Change Land Cover Acres Percent Acres Percent 01 to 06 Agriculture No Change Forest % Decrease Grass/Shrub/Wetland % Increase Water No Change Urban % Decrease Impervious Intensity % % Decrease % Decrease No Change No Change Total Area Total Impervious Area (Percent Impervious Area Excludes Water Area) % Decrease Demographics Round 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 35. These projections are shown in Figure 18 below. Compared to Crow Wing County as a whole, Lake Edward Township has a slightly lower extrapolated growth projection, while the city of Nisswa has a slightly higher extrapolated growth projection (Figure 18). Population Growth Projection Percentage of 06 Population 40% 30% % 10% Lake Edward Township; 06 population: 2,049 City of Nisswa; 06 population: 2,047 Crow Wing County; 06 population: 61,038 0% Extrapolation Figure 18. Population growth projection for Lake Edward Township, the city of Nisswa, and Crow Wing County. Figure excludes First Assessment, which lacks population data(source: RMB Environmental Laboratories, Inc. 15 of 13 Round 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 Round Lake s lakeshed is privately owned and composed primarily 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 06 National Land Cover Dataset). Private (43%) 52% Public (5%) 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 13 Round 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. Unfortunately, the DNR fisheries report, as of 07, shows no Cisco in gill nets in 04 and only 2 in 07, which is a decline from previous monitoring. Round Lake s lakeshed is classified with having 54.3% of the watershed protected and 3.5% 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. Of the 54.3% area protected, the lake itself covers 51.3% of the watershed. Figure 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 Round Lake, whether through direct overland flow or through a creek or river. There are 6 upstream of the Round Lake lakeshed. Percent of the Watershed Protected 0% 75% 100% Round Lake (54.3%) Percent of the Watershed with Disturbed Land Cover 0% 25% 100% Round Lake (3.5%) Figure 19. Round Lake s lakeshed percentage of watershed protected and disturbed. Figure. Upstream lakesheds that contribute water to the Round Lake lakeshed. Color-coded based on management focus (Table 12). RMB Environmental Laboratories, Inc. 17 of 13 Round Lake

18 Status of the Fishery (DNR, as of 07/09/07) Round Lake, at 1,644 acres, is one of the larger and more popular lakes in the Brainerd area. The lake is heavily developed with 36.4 homes/cabins per shoreline mile as of A public access is located on the south side of the lake. The maximum depth is 51' and about 38% of the lake is 15' deep or less. Shallow water substrate is primarily sand, although areas of gravel, rubble, and boulders are also present. The aquatic plant community is relatively diverse with 31 species present and is critical to maintaining healthy fish populations. Emergent plants such as bulrush are important for shoreline protection, maintaining water quality, and provide essential spawning habitat for bass and panfish species. Submerged plants provide food and cover needed by fish and other aquatic species. Walleyes were caught in relatively low numbers in 07 at 3.3/gill net. Average length and weight were 14.8" and 1.3 lbs. Eleven year classes were sampled with age 2 fish (05) accounting for 49% of the gill net catch. These fish measured approximately 11" to 13" at the time of the survey. Northern pike abundance in 07 was typical of past catches on this and similar lakes at 3.7/gill net. Average length and weight were 25.4" and 3.7 lbs. Growth was good with 65% of these fish measuring at least 24". Spring electrofishing for largemouth bass resulted in a catch rate of 64/hr run-time. Mean length of these fish was 11.1" with a PSD of 41 and an RSD-P of 8. Two smallmouth bass were also sampled Black crappie abundance in gill nets was relatively high at 2.9/gill net, while in trap nets it was the lowest to date at 0.4/trap net. The bluegill catch of 44.9/trap net was typical of past catches on this and similar lakes. Yellow perch and Cisco are important forage species for the lake's gamefish. The 07 catch of 22.5 perch/gill net was the lowest since 1942, but is still above the lake class median. Historical abundance of Cisco prior to 04 has ranged from 2.8 to 9.1/gill net. No Cisco were sampled in 04 and only 2 were sampled in 07 (0.1/gill net). See the link below for specific information on gillnet surveys, stocking information, and fish consumption guidelines. Key Findings / Recommendations Monitoring Recommendations Transparency monitoring at site 211 should be continued annually, due to the chemical data collection tied to this specific site and the deeper depth. Sites 2, 3, and 6 have been consistently monitored by volunteers for more than 10 years. Monitoring could continue at these sites as long as the volunteers want to remain active. 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 at site 211, as the budget allows, to track water quality. Round Lake has 13 registered MPCA lake sites. Site 211 is located at a deep spot in the lake and has the most recent and completed chemical data set (Table 4). Due to the variation depth and nearby aquatic vegetation can impact water quality samples, it would be ideal if future chemical data was collected at site 211. RMB Environmental Laboratories, Inc. 18 of 13 Round Lake

19 Overall Conclusions Overall, Round Lake has fair water quality but the lakeshed protection may be at risk. It is a mesotrophic/eutrophic lake (TSI 50) with no detectable trends in water quality. Five percent (5%) of the lakeshed is in public ownership, and 54% of the lakeshed is protected, while only 4% of the watershed is disturbed. Of the 54% that is protected, 52% of this area is open water. Ciscos (Coregonus artedi) can be an early indicator of eutrophication in a lake because they require cold hypolimnetic temperatures and high dissolved oxygen levels. The DNR Fisheries report, as of 07, shows the historical abundance of Cisco prior to 04 has ranged from 2.8 to 9.1/gill net. No Cisco were sampled in 04 and only 2 were sampled in 07 (0.1/gill net). Priority Impacts to the Lake Mean chloride data from site 211 in 10 are above (9.1 mg/l) the typical ecoregion range ( mg/l). Chloride does not affect plant and algae growth at any of these levels, but it can be used as an indicator of possible water pollution from human activity. The most likely sources of chloride, and other containments, are septic systems, animal waste, potassium chloride fertilizer (potash), and road-salting chemicals. Highway 371 also passes along the western shoreline of Round Lake. There is a high potential that runoff from the highway causes road salts and sediment to flow into Round Lake impacting the water quality. Round Lake is heavily developed and the population within the lakeshed is expected to increase significantly over the next -25 years. The DNR Fisheries report states that the lake is heavily developed with 36.4 homes/cabins per shoreline mile as of While most of the land within the first tier of the lake is already developed, additional development within the second tier or within the lakeshed will have the greatest impact to the lakeshed. The southwest shoreline is already developed several tiers out from the first tier. Best Management Practices Recommendations The management focus for Round Lake should be to protect the current water quality and the lakeshed. Efforts should be focused on managing and/or decreasing the impact caused by additional development, including second tier development, and impervious surface area. Project ideas include enforcing county shoreline ordinances, smart development, shoreline restoration, rain gardens, and septic system maintenance. Much of the development around Round Lake is very close to the shoreline. When surface runoff flows through native vegetation, which has a much more robust root system than turf grass, and infiltrates into the soil it acts as a filter, slowing down and removing potential containments in the water. Mitigating the effect large areas of impervious surfaces and septic drain fields located near the shoreline should be a priority for water quality management. Along Highway 371 it is imperative that the entire area between the highway and the lake be covered in vegetation to help filter out additional nutrients and chemicals from entering the lake. 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) RMB Environmental Laboratories, Inc. 19 of 13 Round Lake

20 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. Organizational contacts and reference sites Round Lake Improvement 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 P.O. Box 378, Nisswa, MN 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. of 13 Round Lake