Norway Lake CASS COUNTY

Transcription

1 Norway Lake CASS COUNTY Lake Water Quality Summary Norway Lake is located at Pine River, MN in Cass County. It is a shallow lake covering 524 acres (Table 1). Norway Lake has one inlet and one outlet, which classify it as a drainage lake. Water enters Norway Lake from the Pine River in the north. The Pine River continues in the south of Norway Lake and carries water south into the Whitefish Chain. Norway Lake has been monitored consistently since 1997 (Tables 2-3). These data show that the lake is eutrophic, which is characteristic of a shallow lake with abundant aquatic plants. Norway Lake Association is involved in many activities, including water quality monitoring, and is a member of the Association of Cass County Lakes (ACCL). Table 1. Norway Lake location and key physical characteristics. Location Data Physical Characteristics MN Lake ID: Surface area (acres): 515 County: Cass Littoral area (acres): 515 Ecoregion: Northern Lakes and Forests % Littoral area: 100% Major Drainage Basin: Upper Mississippi River Max depth (ft): 13 Latitude/Longitude: / Inlets: 1 Invasive Species: None as of 2011 Outlets: 1 Public Accesses: 1 Table 2. Availability of primary data types for Norway Lake. Data Availability Transparency data Good data set from Chemical data Inlet/Outlet data Good data set, but not enough for trend analysis. Citizens Stream Monitoring Program (transparency tube) from Recommendations For recommendations refer to page 19. RMB Environmental Laboratories, Inc. 1 of Norway Lake

2 Lake Map Figure 1. Map of Norway Lake with 2010 aerial imagery and illustrations of lake depth contour lines, sample site locations, inlets and outlets, and public access points. The light green areas in the lake illustrate the littoral zone, where the sunlight can usually reach the lake bottom allowing aquatic plants to grow. Table 3. Monitoring programs and associated monitoring sites. Monitoring programs include the Minnesota Pollution Control Agency Lake Monitoring Program (MPCA), Citizen Lake Monitoring Program (CLMP),RMB Environmental Laboratories Lakes Program (RMBEL), Whitefish Chain and Surrounding Lakes WAPOA (WCSL) and Clean Water Legacy Surface Water Monitoring (CWLM). Lake Site Depth (ft) Monitoring Programs 201* Primary site 12 CLMP: , ; CWLM: ; MPCA: 1981; RMBEL: CLMP: ; WCSL: RMB Environmental Laboratories, Inc. 2 of Norway Lake

3 Average Water Quality Statistics The information below describes available chemical data for Norway Lake through 2011 (Table 4). Data for total phosphorus, chlorophyll a, and secchi depth are from the primary site 201. All additional chemical data is from site 201 and reflects mean values from just 1981, 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) 16 <15 Secchi depth (ft) < 6.5 Dissolved oxygen Polymictic see page 8 Interpretation Results are within or slightly above the ecoregion range. This is most likely due to the shallow nature of the lake. Dissolved oxygen depth profiles show that the lake mixes in the summer. Total Kjeldahl Nitrogen Indicates insufficient nitrogen to support summer nitrogeninduced algae blooms. (mg/l) Alkalinity (mg/l) Indicates a low sensitivity to acid rain and a good buffering capacity. Color (Pt-Co Units) Indicates clear water with little to no tannins (brown stain). ph Indicates a hard water lake. Lake water ph less than 6.5 can affect fish spawning and the solubility of metals in the water. Chloride (mg/l) Above the expected range for the ecoregion, but still considered low level. Total Suspended Solids 2 <1-2 Indicates low suspended solids and clear water. (mg/l) Specific Conductance (umhos/cm) Total Nitrogen : Total Phosphorus Within the expected range for the ecoregion. 21:1 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 Norway Lake

4 Water Quality Characteristics - Historical Means and Ranges Table 5. Water quality means and ranges for primary sites. Primary Parameters Site Total Phosphorus Mean (ug/l): 30 Total Phosphorus Min: 18 Total Phosphorus Max: 58 Number of Observations: 23 Chlorophyll a Mean (ug/l): 7 Chlorophyll-a Min: 2 Chlorophyll-a Max: 16 Number of Observations: 23 Secchi Depth Mean (ft): 7 8 Secchi Depth Min: 4 5 Secchi Depth Max: Number of Observations: Figure 2. Norway Lake total phosphorus, chlorophyll a and transparency historical ranges. The arrow represents the range and the black dot represents the historical mean (Primary Site201). Figure adapted after Moore and Thornton, [Ed.] Lake and Reservoir Restoration Guidance Manual. (Doc. No. EPA 440/ ) RMB Environmental Laboratories, Inc. 4 of Norway 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 for Norway Lake ranges from 7.3 to 8.8 feet. The transparency hovers closely around the long-term mean, and doesn t vary much year to year. Transparency monitoring should be continued annually at site 201 in order to track water quality changes. Transparency: Annual Means Secchi Depth (ft) Site 201 Site 202 Mean, Site 201 Figure 3. Annual mean transparency compared to long-term mean transparency. Norway Lake transparency ranges from 4 to 12 ft at the primary site (201). Figure 4 shows the seasonal transparency dynamics. The transparency doesn t change much over the season, which is typical for a shallow 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 Norway Lake

6 Secchi Depth (ft) Seasonal Transparency Dynamics Pattern 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. Norway Lake was rated as being "not quite crystal clear" 64% of the time by samplers between , (Figure 5). 14% 6% Physical Appearance Rating 6% Crystal clear water 13% 3% 64% Not quite crystal clear a little algae visible 13% Definite algae green, yellow, or brown color apparent 3% High algae levels with limited clarity and/or mild odor apparent 64% 14% Severely high algae levels Figure 5. Norway Lake physical appearance ratings by samplers at site 201. RMB Environmental Laboratories, Inc. 6 of Norway Lake

7 As the secchi depth decreases, the perception of recreational suitability of the lake decreases. Norway Lake was rated as having "very minor aesthetic problems" 58% of the time from , (Figure 6). 6% 7% Recreational Suitability Rating 7% Beautiful, could not be better 29% 58% Very minor aesthetic problems; excellent for swimming, boating 29% Swimming and aesthetic enjoyment of the lake slightly impaired because of algae levels 58% 6% 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 at site 201. Total Phosphorus Lake Norway is phosphorus limited, which means that algae and aquatic plant growth is dependent upon available phosphorus. Total phosphorus was evaluated in Norway Lake in 1981 and 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 Figure 7. Historical total phosphorus concentrations (ug/l) for Norway Lake site 201. continue to be monitored to track any future changes in water quality. RMB Environmental Laboratories, Inc. 7 of Norway 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 20 ug/l are perceived as a nuisance. Chlorophyll a (ug/l) Chlorophyll a Minor Algae Chlorophyll a was Figure 8. Chlorophyll a concentrations (ug/l) for Norway Lake at site 201. evaluated in Norway Lake in 1981 and (Figure 8). Chlorophyll a concentrations reached 10 ug/l in most summers monitored, 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 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. Norway Lake is a shallow lake, with a maximum depth of 12 ft. The entire lake is considered littoral zone. Dissolved oxygen profiles from data collected in 2009 at site 201 show that the lake mixes all summer. This is typical for a shallow lake, since the lake is not deep enough to thermally stratify. Figure 9 is a representative DO profile for Norway Lake /28/2009 6/18/2009 7/22/2009 8/19/2009 9/30/2009 Figure 9. Dissolved oxygen profile for Norway Lake in 2009 at site 201. RMB Environmental Laboratories, Inc. 8 of Norway Lake

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 Norway Lake 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). Norway Lake Eutrophic lakes (TSI 50-70) are characteristic of "green" water most of the summer. "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 7). Table 6. Trophic State Index for site 201. Trophic State Index Site 201 TSI Total Phosphorus 53 TSI Chlorophyll-a 50 TSI Secchi 49 TSI Mean 51 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 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 Norway 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. Norway Lake did not have enough data from one site to perform a trend analysis any of the three parameters (Table 8, Figure 11). If the transparency data from sites 201 and 202 are combined, a trend analysis results in no significant trends. Usually, it is bad practice to combine sites for trend analysis, but since Norway Lake is so shallow and both sites are the same depth and in the middle of the lake, an argument could be made to combine sites. Transparency monitoring should continue at site 201 so that this trend can be tracked in future years. Table 8. Trend analysis for Norway Lake. Lake Site Parameter Date Range Trend 201 Total Phosphorus 1981, Insufficient data 201 Chlorophyll a 1981, Insufficient data 201 Transparency Insufficient data 201 & 202 Transparency No trend Transparency Trend for Norway Lake Site 201 Site 202 Secchi Depth (ft) Figure 11. Transparency data for sites 201 and 202. RMB Environmental Laboratories, Inc. 10 of Norway Lake

11 Ecoregion Comparisons 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. 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. Lake Norway is in the Northern Lakes and Forests Ecoregion (Figure 12). The mean total phosphorus, chlorophyll a and transparency (secchi depth) for Norway are slightly poorer 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 0 NLF Ecoregion Norway 0 NLF Ecoregion Norway 25 NLF Ecoregion Norway crystal clear Figures 13a-c. Norway Lake ranges compared to Northern Lakes and Forest Ecoregion ranges. The Norway Lake total phosphorus and chlorophyll a ranges are from 46 data points collected in May-September of 1981, The Norway Lake secchi depth range is from 123 data points collected in May- September from RMB Environmental Laboratories, Inc. 11 of Norway 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. Norway Lake is located in minor watershed (Figure 15). Figure 14. Pine River Major 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. Norway 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 Figure 16. Norway Lake lakeshed ( ) with land ownership, lakes, wetlands, and rivers illustrated. RMB Environmental Laboratories, Inc. 12 of Norway Lake

13 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 Norway Lake s full watershed, containing all the lakesheds upstream of the Norway Lake lakeshed, see page 17. The data interpretation of the Norway Lake lakeshed includes only the immediate lakeshed as this area is the land surface that flows directly into Norway 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. Norway Lake lakeshed vitals table. Lakeshed Vitals Rating Lake Area 515 acres descriptive Littoral Zone Area 515 acres descriptive Lake Max Depth 13 ft. descriptive Lake Mean Depth 5 ft. Water Residence Time NA NA Miles of Stream 5.7 descriptive Inlets 1 Outlets 1 Major Watershed 11 Pine River descriptive Minor Watershed descriptive Lakeshed descriptive Ecoregion Northern Lakes and Forests descriptive Total Lakeshed to Lake Area Ratio (total lakeshed includes lake area) 20:1 Standard Watershed to Lake Basin Ratio (standard watershed includes lake areas) 186:1 Wetland Coverage 13% Aquatic Invasive Species None as of 2011 Public Drainage Ditches None Public Lake Accesses 1 Miles of Shoreline 4.1 descriptive Shoreline Development Index 1.3 Public Land to Private Land Ratio 0.2:1 Development Classification General Development Miles of Road 28.5 descriptive Municipalities in lakeshed 1 Pine River Forestry Practices None Feedlots None Sewage Management Individual Waste Treatment Systems, lakewide inspection conducted in 2003 Lake Management Plan Healthy Lakes and Rivers Program, 2000 Lake Vegetation Survey/Plan MNDNR, 2009 RMB Environmental Laboratories, Inc. 13 of Norway 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 Figure 17. Norway Lake lakeshed ( ) land cover ( 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 Norway Lake 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 that is comparable over a decade s time. Table 10 describes Norway Lake 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 grass/shrub/wetland cover (43.8%). In addition, the urban acreage has increased, which has implications for storm water runoff into the lake. RMB Environmental Laboratories, Inc. 14 of Norway Lake

15 Table 10. Norway Lake s lakeshed land cover statistics and % change from 1990 to 2000 ( % Change Land Cover Acres Percent Acres Percent 1990 to 2000 Agriculture % Decrease Forest % Increase Grass/Shrub/Wetland % Decrease Water % Decrease Urban % Increase Impervious Intensity % % Decrease % Increase % Increase % Increase % Decrease % Decrease % Decrease Total Area Total Impervious Area (Percent Impervious Area Excludes Water Area) % Decrease Demographics Norway 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 Compared to Cass County as a whole, the Barclay and Pine River townships have similar growth projections (Figure 18). (source: Figure 18. Population growth projection for Barclay and Pine River Townships and Cass County. Percentage of 2006 Population 50% 40% 30% 20% 10% 0% Population Growth Projection Barclay Township; 2006 population: 512 Pine River Township; 2006 population: 1209 Cass County; 2006 population: 28, Extrapolation RMB Environmental Laboratories, Inc. 15 of Norway Lake

16 Norway Lake 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 Norway Lake s lakeshed is privately-owned 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 Norway lakeshed (Sources: Cass County parcel data, National Wetlands Inventory, and the 2006 National Land Cover Dataset). (Note: the high percentage of land in Other land use category due to significant disagreement between NWI and NLCD wetlands) Developed Private (77%) 8% Public (15%) Forested Open Agriculture Uplands Other Wetlands Water County State Federal Land Use (%) 3.2% 14% 29% 20.8% 10% 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 Norway Lake

17 Table 12. Suggested approaches for watershed protection and restoration of DNR-managed fish lakes in Minnesota. Watershed Disturbance (%) Watershed Protected (%) Management Type Comments < 25% > 75% Vigilance < 75% Protection Sufficiently protected -- Water quality supports healthy and diverse native fish communities. Keep public lands protected. Excellent candidates for protection -- Water quality can be maintained in a range that supports healthy and diverse native fish communities. Disturbed lands should be limited to less than 25% % n/a Full Restoration > 60% n/a Partial Restoration Realistic chance for full restoration of water quality and improve quality of fish communities. Disturbed land percentage should be reduced and BMPs implemented. Restoration will be very expensive and probably will not achieve water quality conditions necessary to sustain healthy fish communities. Restoration opportunities must be critically evaluated to assure feasible positive outcomes. The next step was to prioritize lakes within each of these management categories. DNR Fisheries identified high value fishery lakes, such as cisco refuge lakes. Ciscos (Coregonus artedi) can be an early indicator of eutrophication in a lake because they require cold hypolimnetic temperatures and high dissolved oxygen levels. These watersheds with low disturbance and high value fishery lakes are excellent candidates for priority protection measures, especially those that are related to forestry and minimizing the effects of landscape disturbance. Forest stewardship planning, harvest coordination to reduce hydrology impacts and forest conservation easements are some potential tools that can protect these high value resources for the long term. Norway Lake s lakeshed is classified with having 19.8% of the watershed protected and 20.1% of the watershed disturbed (Figure 19). Therefore, this lakeshed should have a protection focus. Goals for the lake should be to limit any increase in disturbed land use. Figure 20 displays the upstream lakesheds that contribute water to the lakeshed of interest. All of the land and water area in this figure has the potential to contribute water to Norway Lake, whether through direct overland flow or through a creek or river. Thirty-three of the 38 upstream lakesheds have the same management focus (protection). Percent of the Watershed Protected 0% 75% 100% Norway Lake (19.8%) Percent of the Watershed with Disturbed Land Cover 0% 25% 100% Norway Lake (20.1%) Figure 19. Norway Lake s lakeshed percentage of watershed protected and disturbed. Figure 20. Upstream lakesheds that contribute water to the Norway lakeshed. Color-coded based on management focus (table 12). RMB Environmental Laboratories, Inc. 17 of Norway Lake

18 Conservation Easement Potential In an ever-growing society, today s landscapes are being urbanized more and more to sustain the ever-growing population and behavior of recreational usage. In Minnesota, the land of ten thousand lakes, it is only natural to develop properties within the boundaries and beauty of our lakes and streams. Conservation efforts to limit or slow down the development process can only assist in the preservation of the lakeshed and inevitably the water quality of water bodies found within. Figure 21 identifies parcels within the lakeshed that are large enough to warrant the investigation of parcel conservation practices and purchase. Figure 21. Lake parcels with conservation potential (developed by John Snyder, LLAWF). RMB Environmental Laboratories, Inc. 18 of Norway Lake

19 Status of the Fishery (DNR, as of 06/15/2009) Norway Lake is located on the Pine River north of the City of Pine River in Cass County. Water levels are maintained by a dam in Pine River about one mile downstream from the main lake basin. With a maximum depth of about 12 ft, aquatic vegetation can be found throughout the lake, but is most abundant in the western portion of the lake. Natural vegetation along lakeshores is critical habitat for most aquatic species for at least a portion of their life. Public accesses are located in the southwest bay and on the north shore east of the Pine River inlet, although parking is limited at the north access. A fishing pier is located on the west shore in the City north of the dam. A fisheries population assessment was conducted on Norway Lake in June 2009 with four gill net sets and eight trap net sets. Northern pike were the most abundant fish in the gill net catch (20.3 per net) and were caught at well above the normal catch rate for similar lakes in Minnesota. A wide size range of northern pike were captured, from 9.5 to 34.2 inches long with most fish from 13 to 31 inches. Yellow perch were the second most common fish in the gill net catch (13.3 per net) with catch near normal compared to similar lakes. Yellow perch ranged from 4.7 to 11.2 inches with a mean length of 8.1 inches. Trap net catches were comprised primarily of bluegills (90.8 per net) with pumpkinseed sunfish (9.6 per net) the second most common fish. Both of these species were caught at above normal numbers compared to similar lakes. Most bluegills were around 5 to 6 inches long with the largest at 8.1 inches. Only one largemouth bass was captured in the survey, although a few other largemouth bass were observed in the southwest bay near the access. Largemouth bass are usually not captured very well in survey nets. Other species that could provide angling opportunities include black crappie, bullheads, rock bass, and bowfin. 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 201 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 at site 201, as the budget allows, to track trends in water quality. Overall Conclusions Norway Lake has typical water quality for a shallow lake. It is a eutrophic lake (TSI=51) with stable transparency (Figure 11). Fifteen percent (15%) of the lakeshed is in public ownership, and 19% of the watershed is protected, while 20% of the watershed is disturbed (Figure 18). Priority Impacts to the lake There are three priority impacts to Norway Lake. The first is current and additional development. The first tier is developed all along the lakeshore. The second tier is heavily developed on the south side of the lake, which extends into the City of Pine River. Since the lake is adjacent to the RMB Environmental Laboratories, Inc. 19 of Norway Lake

20 City of Pine River, it has increased development pressure. The urban acreage around the lake increased by 128 acres from In addition, Norway Lake is classified by the DNR as a general development lake, which is usually a classification used for larger deeper lakes. Norway Lake most likely has this designation due to its proximity to the City of Pine River. Extra vigilance and planning must be taken for new development since the shoreline classification does not sufficiently protect the lake. A second impact is the shallow nature of the lake. Because Norway Lake is a shallow lake, it is very important to protect native aquatic plant beds to preserve fish habitat and water clarity. In addition, large boat motors can churn up the sediment and re-suspend phosphorus, causing algae blooms. A third impact is the large watershed (186:1 watershed to lake area ratio). The cumulative addition of nutrients along the Pine River upstream most likely impact the lake. Best Management Practices Recommendations The management focus for Norway Lake should be to protect the current water quality and the lakeshed. Extra vigilance and planning must be taken for new development since the shoreline classification does not sufficiently protect the lake. Efforts should be focused on managing and/or decreasing the impact caused by current and additional development, including second tier 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. 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. Studies have shown that large boat motors can re-suspend the phosphorus from the lake s sediment and cause algae blooms. Boaters should be encouraged to drive slowly through areas shallower than 10 feet. Making sure the Pine River and its tributaries have sufficient stream buffers can protect the lake from future nutrient loading. There are some large parcels of land that could be protected with conservation easements. See Figure 21 for the location of these parcels. Project Implementation The best management practices above can be implemented by a variety of entities. Some possibilities are listed below. Individual property owners Shoreline restoration Rain gardens Aquatic plant bed protection (only remove a small area for swimming) Lake Associations Lake condition monitoring Ground truthing visual inspection upstream on stream inlets Watershed mapping by a consultant Shoreline inventory study by a consultant RMB Environmental Laboratories, Inc. 20 of Norway Lake

21 Soil and Water Conservation District (SWCD) and Natural Resources Conservation Service (NRCS) Shoreline restoration Stream buffers Wetland restoration Organizational Contacts and Reference Sites Norway Lake Association Cass County Soil and Water Conservation District DNR Fisheries Office Regional Minnesota Pollution Control Agency Office County-MN/ Courthouse, 1st Floor, 303 Minnesota Avenue W, PO Box 3000, Walker, MN, State 371 Northwest, Walker, MN, College Road, Suite 105, Baxter, MN , RMB Environmental Laboratories, Inc. 21 of Norway Lake