Cottonwood

A targeted gillnet survey was conducted during early September of 2025 on Cottonwood Lake. We conducted the survey to assess relative abundance and size structure of Northern Pike in Cottonwood Lake. A targeted survey is generally used for sampling a specific kind of fish or time of year (i.e. spawning season, fall season, etc.) unlike a standard survey which samples a wider range of fish species during the summer months using standard methodology (i.e. standard time of year, set sampling stations, taking water clarity readings and oxygen/temperature profiles, etc.) and gears (i.e. lake survey gillnets, trapnets, and spring electrofishing for Largemouth Bass). Cottonwood is a small (379 acres), shallow (7 feet maximum), aerated (6 unit helixor system and floating surface type aerators), and productive lake located in Lyon County. There are two boat accesses and a park located along the lakeshore. A significant winterkill last occurred during late January or early February of 2013 on Cottonwood Lake. A 2013 spring ice out netting confirmed a significant winterkill of Walleye, Black Crappie and Common Carp. However, enough Common Carp survived to produce large year classes in later years. Other fish species (Yellow Perch, Northern Pike and Black Bullhead) were relatively unaffected. Significant winterkill occurred on nearby School Grove Lake in 2019 due to intense fall algae blooms. Nearby Wood Lake experienced significant winterkill in 2022. Late snowfall accumulations in January or early February have lowered dissolved oxygen levels (<1 ppm) in shallow area lakes in recent years. Winter oxygen levels were low in February of 2023 on nearby School Grove due in part to heavy snowfall events. Gamefish often become susceptible to winterkill when oxygen levels are less than 1 ppm for an extended period. Ice out occurred in mid-March of 2023. There were reports of winterkill (Common Carp and Walleye) in the spring of 2023 in both School Grove and Lady Slipper. Although no winterkill occurred in Cottonwood, nearby Sham Lake (Walleye rearing pond) had a significant winterkill in February/March of 2023. Cottonwood Lake aeration system maintained adequate winter oxygen levels during the 2022-23 winter. Winter oxygen levels were also adequate during the 2023-2024 and 2024-2025 winters for area lakes due to mild winter conditions. Aerators were not run in 2025-26 winter due to mild conditions and high oxygen levels in Cottonwood and surrounding lakes (i.e. Wood, Tyson, School Grove, and Lady Slipper). Water clarity was moderate (4.0 feet) with excellent dissolved oxygen levels (9 ppm) on September 9, 2025 for Cottonwood. Shoalwater substrates include boulder, rubble, gravel, sand, and silt. The fine sediments compose most of the lake substrates. Water levels above normal during the spring and summer, but normal by fall of 2025. Submergent vegetation densities were moderate in 2025 which included mostly sago pondweed. Blue-green algae blooms were moderate during the 2025 summer and fall. Intense blue-green algal blooms are common during the summer due to agricultural, residential, municipal and golf course nutrient runoff. There are approximately 15 drain tile, culvert and storm sewer inlets that enter Cottonwood Lake. The three largest inlets are ditches that enter the southeast (County Ditch#69), north (Judicial Ditch#18) and southwest corners of the lake. An outlet dam is located along the northwest shore. The outlet structure is inadequate at preventing fish movement (i.e. Common Carp, Northern Pike and Bowfin) into Cottonwood during high water events. The outlet flows into Judicial Ditch#24, which drains into the Yellow Medicine River and eventually the Minnesota River. Prior to 1993, angling for game fish species was limited due to frequent winterkills. Angling opportunities have increased dramatically following the 1993 reclamation and subsequent operation of aeration units in Cottonwood. Local residents have reported high shore fishing catches of small (< 22.00 inches) Northern Pike during recent years. The current southern zone Northern Pike regulation only allows the harvest of Northern Pike 24.00 inches or larger from Cottonwood Lake. Black Bullhead abundance was moderate in 2025 (26.00 fish/gillnet). The Black Bullhead historical average gillnet catch rate is 86.24 fish/gillnet. The 2025 Black Bullhead average size was large (0.73 pounds and 10.83 inches) from gillnets. The Black Bullhead historical average weight is 0.45 pounds from gillnets for Cottonwood. The largest Black Bullhead captured was 13.43 inches in 2025. Common Carp abundance was moderate in 2025 (3.00 fish/gillnet). The Common Carp historical catch rate is 9.41 fish/gillnet for Cottonwood. The 2025 Common Carp average size was moderate (3.36 pounds and 17.08 inches) from gillnets. The Common Carp historical average weight is 2.26 pounds from gillnets for Cottonwood. Black Crappie were not present in the 2017, 2022 or 2025 survey nets. Black Crappie were only sampled in Cottonwood surveys during 2007 (0.44 fish/trapnet, 9.25 inches average) and 2012 (4.11 fish/trapnet, 12.83 inches average). Black Crappie adults were last stocked (632 fish, 158 pounds) into Cottonwood during 2008. Bluegill were not sampled in the 2017, 2022 or 2025 survey nets. The Bluegill historical catch rate is 1.74 fish/trapnet for Cottonwood. Channel Catfish were not caught in survey nets since 2007. Low numbers were caught in Cottonwood during 1997 and 2007 surveys. Channel Catfish fingerlings were first stocked into Cottonwood during 1994 (6,730 fish) and recently in 2008 (3,250 fish). Northern Pike abundance was high in 2025 (7.00 fish/gillnet). The Northern Pike historical average catch rate is 3.94 fish/gillnet for Cottonwood. Abundant shallow in-lake habitat (sago pondweed) and inlet/outlet connections for immigration to potential spawning habitat (wetlands and river systems) have produced large year classes of Northern Pike for Cottonwood Lake. There were abundant numbers of small sized Northern Pike captured in surveys from 2002 (7.33 fish/gillnet, 1.66 pounds average weight) and 2012 (15.00 fish/gillnet, 2.30 pounds average weight). Low numbers were present in the 2017 gillnets (1.00 fish/gillnet, 1.24 pounds average weight). Moderate numbers (2.67 fish/gillnet, 2.85 pounds average weight) were present in the 2022 survey. The 2025 Northern Pike average size was small (2.03 pounds and 20.94 inches) from gillnets. Northern Pike historical average weight is 2.02 pounds from gillnets. Northern Pike growth rates were slow for ages 1-3. The 2023 and 2022 year classes comprised 57% and 43% respectively of the 2025 Northern Pike catch. The largest Northern Pike captured was 25.71 inches in 2025. Cottonwood Lake is in the Southern Northern Pike Regulation zone which allows anglers and spearers to keep two Northern Pike daily, with a minimum size of 24.00 inches. Only one Northern Pike was captured over 24.00 inches in the 2025 gillnet survey. Local residents have recently reported high catches of small size Northern Pike with few over 24.00 inches in Cottonwood. The Northern Pike zone regulation is currently not justifiable due to slow growth and abundant numbers of small sized Northern Pike in Cottonwood Lake. Yellow Perch abundance was moderate in 2025 (17.00 fish/gillnet). The Yellow Perch historical average catch rate is 31.54 fish/gillnet for Cottonwood. The 2025 Yellow Perch average size was large (0.55 pounds and 9.96 inches) from gillnets. The Yellow Perch historical average length is 8.44 inches. The largest Yellow Perch captured was 12.28 inches in 2025. Yellow Perch were last stocked in 2013 (8,554 yearlings, 329 pounds; 442 adults, 138 pounds). Walleye natural reproduction has been generally insignificant based on previous surveys for Cottonwood. Walleye fry are generally stocked (160,000-250,000) every other year in Cottonwood, after a fry stocking failure or winterkill occurrence. Walleye fry (124,769 fish) were last stocked in May of 2025. Other recent Walleye fry stockings (102,000 - 250,000 fish) included 2008-2011, 2013-2014, 2016, 2018, and 2021-2025. Additionally, Walleye fingerlings and yearlings had been previously stocked into Cottonwood during late September of 2004 (12,130 fish, 715 pounds), January of 2010 (16,800 fingerlings, 700 pounds-private stocking), May of 2010 (124 yearlings/adults, 19 pounds), fall of 2011 (5,152 yearlings; 260 fingerlings; and 82 adults; 742 pounds total), fall of 2014 (29 fish, 38 pounds) and fall of 2020 (416 yearlings, 277 pounds; 69 adults, 137 pounds). Low young of year "YOY" Walleye numbers (14.00 YOY/hour, 8.35 inches) were caught in the 2023 fall night electrofishing survey. Moderate numbers of young of year "YOY" Walleye (36.00 YOY/hour, 6.35 inches) were caught in a daytime fall electrofishing survey. YOY Walleye are probably more numerous than documented in 2022 due to daytime electrofishing being less effective than nighttime electrofishing for catching YOY Walleye. Abundant numbers of large sized YOY Walleye were captured in the 2016 (86.00 YOY/hour, 8.17 inches) and 2018 (210.00 YOY/hour, 8.33 inches) fall night electrofishing surveys. Moderate numbers of YOY Walleye (48.00 YOY/hour, 6.16 inches) were captured in the 2014 fall night electrofishing survey. No YOY Walleye were captured in the 2013 fall electrofishing survey. However, there were abundant YOY Northern Pike (102.22 YOY/hour, 7.70 inches) captured in the 2013 fall electrofishing survey. No fall YOY Walleye electrofishing surveys were conducted in 2020-2021 and 2024-2025. Walleye abundance was high in 2025 (27.00 fish/gillnet). The Walleye historical average catch rate is 25.76 fish/gillnet for Cottonwood. The 2025 Walleye average size was moderate (1.11 pounds and 14.30 inches) from gillnets. Walleye historical average weight is 1.28 pounds from gillnets. The 2025 Walleye catch rate of quality size (15.00 inches and larger) was high (10.00 fish/gillnet). The largest Walleye captured was 21.18 inches in 2025. Walleye growth rates were fast for ages 1-5. The 2023 (fry stocked year) accounted for 74% of the 2025 Walleye gillnet catch. Other fish species captured in 2025 included low to moderate numbers of White Sucker (1.00 fish/gillnet) and Yellow Bullhead (2.00 fish/gillnet). The average weights were 2.27 pounds and 1.05 pounds respectively for White Sucker and Yellow Bullhead. Current fish management activities on Cottonwood include monitoring the fish population on a periodic basis, monitoring winter dissolved oxygen levels, assisting local residents and the sportsman's club with the operation of the aeration system, protecting aquatic vegetation through the permit process, assisting aquatic plant management and enforcement personnel in educating boaters and monitoring access sites for potential invasive species introductions, participating in local watershed initiatives, and stocking various fish species as warranted. Cottonwood Lake will be surveyed for all fish species in the 2027 summer and 2027 fall for YOY Walleye.

A targeted fall night electrofishing survey was conducted on Cottonwood Lake during September 11, 2023 to evaluate young of year "YOY" (fingerling sized) Walleye numbers due to a fry stocking. Three stations were sampled for a total of 30 minutes. The water temperature was 67 F. Water clarity was poor (3 inches) due to a blue-green algae bloom. We observed abundant numbers of YOY Yellow Perch, moderate numbers of adult Walleye, low numbers of Common Carp and Northern Pike. A targeted survey is generally used for sampling a specific kind of fish or time of year (i.e., spawning season, fall season, etc.) unlike a standard survey which samples a wider range of fish species during the summer months using standard methodology (i.e., standard time of year, set sampling stations, taking water clarity readings and oxygen/temperature profiles, etc.) and gears (i.e. lake survey gillnets, trapnets and possibly spring electrofishing for Largemouth Bass). Cottonwood is a small (383 acres), shallow (7 feet maximum), aerated (6 unit helixor system and floating surface type aerators), and productive lake located in Lyon County. A significant winterkill last occurred during late January or early February of 2013 on Cottonwood Lake. Walleye natural reproduction has been generally insignificant based on previous surveys for Cottonwood. Walleye fry were generally stocked (160,000-250,000) every other year in Cottonwood, after a fry stocking failure or winterkill occurrence. Walleye fry (175,828 fish) were last stocked in May of 2023. Other recent Walleye fry stockings (180,000 - 250,000 fish) included 2008-2011, 2013-2014, 2016, 2018 and 2021-2022. Walleye fry are currently scheduled for annual stockings of 125,000 fish. Walleye fingerlings and yearlings had been previously stocked into Cottonwood during late September of 2004 (12,130 fish, 715 pounds), January of 2010 (16,800 fingerlings, 700 pounds-private stocking), May of 2010 (124 yearlings/adults, 19 pounds), fall of 2011 (5,152 yearlings, 260 fingerlings and 82 adults; 742 pounds), fall of 2014 (29 fish, 38 pounds), fall of 2020 (416 yearlings, 277 pounds; 69 adults, 137 pounds) and fall of 2021 (126 adults, 197 pounds). Low numbers of young of year "YOY" Walleye (14.00 YOY/hour, 8.35 inches) were caught in a 2023 nighttime fall electrofishing survey. Local residents reported seeing dead small Walleye along the Cottonwood near shore areas during early July of 2023. Moderate numbers of YOY Walleye (36.00 YOY/hour, 6.35 inches) were caught in a 2022 daytime fall electrofishing survey. YOY Walleye are probably more numerous than documented in 2022 due to daytime electrofishing being less effective than nighttime electrofishing for catching YOY Walleye. Abundant numbers of large sized YOY Walleye were captured in the 2018 (210.00 YOY/hour, 8.33 inches) and 2016 (86.00 YOY/hour, 8.17 inches) fall night electrofishing surveys. Moderate numbers of YOY Walleye (48.00 YOY/hour, 6.16 inches) were captured in the 2014 fall night electrofishing survey. No yearling Walleye were caught in 2023 fall electrofishing survey. Abundant YOY Northern Pike (102.22 YOY/hour, 7.70 inches) captured in the 2013 fall electrofishing survey. No fall YOY Walleye electrofishing surveys were conducted in 2020-2021. Adult Walleye were abundant (17.00 fish/gillnet) in the most recent 2022 summer standard gillnet and trapnet survey. Walleye average weight and length were 2.14 pounds and 17.87 inches from gillnets. Walleye growth rates were excellent. The 2019 year class (yearling/adult stocked and/or natural reproduction) accounted for 58% of the 2022 Walleye summer survey catch. Cottonwood Lake will be surveyed for all fish species in 2027. Fall electrofishing surveys will be conducted periodically during Walleye fry stocked years.

A standard survey was conducted during late-June of 2022 on Cottonwood Lake. A targeted survey is generally used for sampling a specific kind of fish or time of year (i.e. spawning season, fall season, etc.) unlike a standard survey which samples a wider range of fish species during the summer months using standard methodology (i.e. standard time of year, set sampling stations, taking water clarity readings and oxygen/temperature profiles, etc.) and gears (i.e. lake survey gillnets, trapnets, and spring electrofishing for Largemouth Bass). A fall daytime electrofishing survey for young of year "YOY" (fingerling sized) Walleye was conducted in late August of 2023. Cottonwood is a small (379 acres), shallow (7 feet maximum), aerated (6 unit helixor system and floating surface type aerators), and productive lake located in Lyon County. There are two boat accesses and a park located along the lakeshore. A partial winterkill may have occurred in February of 2010. A significant winterkill last occurred during late January or early February of 2013 on Cottonwood Lake. A winter storm sunk one of the two surface aerators in February of 2013, but was replaced shortly afterward. A 2013 spring ice out netting confirmed a significant winterkill of Walleye, Black Crappie and Common Carp. However, enough Common Carp survived to produce large year classes in later years. Other fish species (Yellow Perch, Northern Pike and Black Bullhead) were relatively unaffected. The helixor system has struggled to maintain adequate oxygen levels during moderate to severe winters, but no winterkill after 2013 has been documented. Significant winterkill occurred on nearby School Grove Lake in 2019 due to intense fall algae blooms. Nearby Wood Lake experienced significant winterkill in 2022. Late snowfall accumulations in January or early February have lowered dissolved oxygen levels (<1 ppm) in shallow area lakes in recent years. However, winterkill severity and occurrence has been sporadic on these lakes. Water clarity was moderate (3.0 feet) on June 27, 2022 for Cottonwood. Shoalwater substrates include boulder, rubble, gravel, sand, and silt. The fine sediments compose most of the lake substrates. Water levels have been low during recent summers. Submergent vegetation densities were moderate in 2022 which included sago pondweed, small pondweed and coontail. Other less desirable aquatic vegetation species included filamentous algae and water moss. Emergent and terrestrial vegetation species included low densities of cattail, bulrush, reed canary grass, cane and swamp milkweed located mostly in the northwest corner of the lake. Intense blue-green algal blooms are common during the summer due to agricultural, residential, municipal and golf course nutrient runoff. Nutrient levels were extremely high (total phosphorus=0.221 ppm, chlorophyll a=237 ppb) in June of 2012. There are approximately 15 drain tile, culvert and storm sewer inlets that enter Cottonwood Lake. The three largest inlets are ditches that enter the southeast (County Ditch#69), north (Judicial Ditch#18) and southwest corners of the lake. An outlet dam is located along the northwest shore. The outlet structure is inadequate at preventing fish movement (i.e. Common Carp, Northern Pike and Bowfin) into Cottonwood during high water events. The outlet flows into Judicial Ditch#24, which drains into the Yellow Medicine River and eventually the Minnesota River. Prior to 1993, angling for game fish species was limited. Angling opportunities have increased dramatically following the 1993 reclamation and subsequent operation of aeration units in Cottonwood. Submergent vegetation (sago pondweed) increased substantially after the 1993 reclamation, however sago has declined in abundance over the last 24 years resulting in heavy algal blooms in Cottonwood. Primary species managed in Cottonwood include Walleye and Yellow Perch. Black Bullhead abundance was low (19.44 fish/trapnet) in 2022. The Black Bullhead historical average trapnet catch rate is 85.06 fish/trapnet. The 2022 Black Bullhead gillnet catch rate (32.00/gillnet) was also below the historical average (93.77 fish/gillnet). The 2022 Black Bullhead average size was large (0.64 pounds and 9.9 inches) from trapnets. The Black Bullhead historical average weight is 0.46 pounds from trapnets for Cottonwood. Common Carp abundance low to moderate (3.00 fish/gillnet, 5.56 fish/trapnet) in 2022. The Common Carp historical catch rates are 10.21 fish/gillnet and 6.22 fish/trapnet for Cottonwood. The 2022 Common Carp average weights were small (2.08 pounds and 4.15 pounds respectively from gillnets and trapnets. Black Crappie were not present in the 2022 or 2017 survey nets. Black Crappie were only sampled in Cottonwood surveys during 2007 (0.44 fish/trapnet, 9.3 inches average) and 2012 (4.11 fish/trapnet, 12.8 inches average). Black Crappie adults were last stocked (632 fish, 158 pounds) into Cottonwood during 2008. Bluegill were not sampled in the 2022 or 2017 survey nets. The Bluegill historical catch rate is 1.99 fish/trapnet for Cottonwood. Channel Catfish were last caught in the 2007 survey. Low numbers were caught in Cottonwood during 1997 and 2007 surveys. Channel Catfish fingerlings were first stocked into Cottonwood during 1994 (6,730 fish) and recently in 2008 (3,250 fish). Northern Pike abundance was moderate (2.67 fish/gillnet) in 2022 for Cottonwood. The Northern Pike historical average catch rate is 3.56 fish/gillnet for Cottonwood. There were abundant numbers (15.00 fish/gillnet) of small sized (2.30 pounds) Northern Pike in the 2012 gillnets. Low numbers were present in the 2017 gillnets (1.07 fish/gillnet). The 2022 Northern Pike average size was moderate to small (2.85 pounds and 23.2 inches) from gillnets. Northern Pike historical average weight was 2.02 pounds from gillnets. Northern Pike growth rates were good for ages 1-4, but slow for ages 5-7. The 2018 year class comprised 33% of the 2022 Northern Pike catch. Abundant YOY Northern Pike numbers (102.22 YOY/hour, 7.7 inches) due to natural reproduction were captured in a 2013 fall electrofishing survey. Historically, unfavorable conditions (lack of submergent vegetation, poor clarity, and low Yellow Perch numbers) had not been conducive for Northern Pike survival and abundance in Cottonwood unlike in recent years. In the Southern zone, anglers and spearers can keep two Northern Pike, with a minimum size of 24.0 inches. Yellow Perch were abundant (124.00 fish/gillnet) in 2022. The Yellow Perch historical average catch rate is 33.35 fish/gillnet for Cottonwood. The 2022 Yellow Perch average size was moderate (7.5 inches and 0.25 pounds) from gillnets. The Yellow Perch historical average length is 8.2 inches. Yellow Perch growth rates were good to excellent for ages 1-8. The 2020 year class comprised 59% of the 2022 Yellow Perch gillnet catch. Yellow Perch were last stocked in 2013 (8,554 yearlings, 329 pounds; 442 adults, 138 pounds). Walleye natural reproduction has been generally insignificant based on previous surveys and analysis for Cottonwood. Walleye fry are generally stocked (160,000-250,000) every other year in Cottonwood, after a fry stocking failure or winterkill occurrence. Walleye fry (188,901 fish) were last stocked in May of 2022. Other recent Walleye fry stockings (180,000 - 250,000 fish) included 2008-2011 and 2013-2014, 2016, 2018 and 2021. Additionally, Walleye fingerlings and yearlings had been previously stocked into Cottonwood during late September of 2004 (12,130 fish, 715 pounds), January of 2010 (16,800 fingerlings, 700 pounds-private stocking), May of 2010 (124 yearlings/adults, 19 pounds), fall of 2011 (5,152 yearlings, 260 fingerlings and 82 adults; 742 pounds), fall of 2014 (29 fish, 38 pounds) and fall of 2020 (416 yearlings, 277 pounds; 69 adults, 137 pounds). Most of the recent stockings of Walleye yearlings and adults have come from nearby Sham Lake rearing pond. Moderate numbers of young of year "YOY" Walleye (36.00 YOY/hour, 6.35 inches) were caught in a daytime fall electrofishing survey. YOY Walleye are probably more numerous than documented in 2022 due to daytime electrofishing being less effective than nighttime electrofishing for catching YOY Walleye. Abundant numbers of large sized YOY Walleye were captured in the 2016 (86.00 YOY/hour, 8.2 inches) and 2018 (210.00 YOY/hour, 8.3 inches) fall night electrofishing surveys. Moderate numbers of YOY Walleye (48.00 YOY/hour, 6.2 inches) were captured in the 2014 fall night electrofishing survey. No yearling Walleye were caught in 2014 or 2016 fall electrofishing surveys. No YOY Walleye were captured in the 2013 fall electrofishing survey. No fall YOY Walleye electrofishing surveys were conducted in 2020-2021. Walleye were abundant (17.00 fish/gillnet) in 2022. The Walleye historical average catch rate is 25.60 fish/gillnet for Cottonwood. The 2022 Walleye trapnet catch rate was moderate (4.78 fish/trapnet). The 2022 Walleye average size was moderate (2.14 pounds and 17.9 inches) from gillnets. Walleye historical average weight is 1.31 pounds from gillnets. The 2022 Walleye catch rate of quality size (15.0 inches plus) was high (15.67 fish/gillnet). The 2022 catch rate of preferred size Walleye (20.0 inches plus) was moderate (2.33 fish/gillnet). Walleye growth rates were excellent for ages 1-8. The 2019 (yearling/adult stocked and/or natural reproduction) accounted for 58% of the 2022 Walleye catch. Current fish management activities on Cottonwood include monitoring the fish population on a periodic basis, monitoring winter dissolved oxygen levels, assisting local residents and the sportsman's club with the operation of the aeration system, protecting aquatic vegetation through the permit process, assisting aquatic plant management and enforcement personnel in educating boaters and monitoring access sites for potential invasive species introductions, participating in local watershed initiatives, and stocking various fish species as warranted. Cottonwood Lake will be surveyed for all fish species in the 2027 summer and 2024 fall for YOY Walleye.

Based on Minnesota DNR survey data, anglers target Walleye, Yellow Perch, Bluegill, Black Crappie, and Northern Pike in Cottonwood. See the full species list above for catch rates, size structure, and quality scores.

Minnesota DNR records list public access for Cottonwood. Check the DNR LakeFinder page for the launch type and directions before you go.

Cottonwood has a maximum depth of 7 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Cottonwood is from 2025.

No invasive species are on record for Cottonwood in Minnesota DNR data. Always clean, drain, and dry your equipment to help keep it that way.