Impaired Lakes in Wisconsin
145 of 388 graded Wisconsin lakes (37%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 14 have an approved TMDL restoration plan.
Top Causes of Impairment in Wisconsin
All 145 EPA-Listed Impaired Lakes in Wisconsin
| Lake | County | Grade | Causes | TMDL |
|---|---|---|---|---|
| Lake Capri | St. Francois | A | Nutrients (phosphorus, nitrogen) | — |
| Lake Wauwanoka Nr. Dam | Jefferson | A | Nutrients (phosphorus, nitrogen) | — |
| Lake Marseilles-Terre du Lac Lakes | St. Francois | A | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Shayne-Terre du Lac Lakes | Washington | A | Nutrients (phosphorus, nitrogen) | — |
| Timberline Lakes | St. Francois | A | Nutrients (phosphorus, nitrogen) | — |
| Lake Taneycomo Ab. Bee Cr. Arm | Taney | A | Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Taneycomo Nr. Roark Cr. | Taney | A | Nutrients (phosphorus, nitrogen) | ✓ |
| Fourche Creek Lake | Ripley | A | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Fox Valley Lake | Clark | B | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Fellows Lake | Greene | B | Mercury | — |
| Lake Taneycomo | Taney | B | Nutrients (phosphorus, nitrogen) | ✓ |
| North Bethany City Reservoir | Harrison | B | Mercury | — |
| Forest Lake | Adair | B | Algal growth, Mercury | — |
| Lake of the Woods | Boone | B | Mercury | — |
| Lake Buteo | Johnson | B | Mercury | — |
| James R. Just Ab. Lake Springfield | Greene | B | Algal growth | — |
| Weatherby Lake | Platte | B | Algal growth, Mercury, Nutrients (phosphorus, nitrogen) | — |
| Table Rock Lake | Stone | B | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Table Rock L. Ab. Oswalt Bluff Lake | Stone | B | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake 37 | St. Charles | B | Mercury | — |
| Lake Taneycomo | Taney | B | Nutrients (phosphorus, nitrogen) | ✓ |
| Milan Lake North | Sullivan | B | Algal growth | — |
| Waukomis Lake | Platte | C | Nutrients (phosphorus, nitrogen) | — |
| Little Prairie Lake by Dam | Phelps | C | Mercury | — |
| Bowling Green Lake | Pike | C | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Clearwater Lake | Reynolds | C | Algal growth, Mercury | — |
| Hazel Creek Lk. Lake | Adair | C | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Little Prairie Lake | Phelps | C | Mercury | — |
| Peaceful Valley Lake | Gasconade | C | Algal growth | — |
| Knob Noster S.P. Lake 2 | Johnson | C | Mercury | — |
| Forest Lake Se Branch | Adair | C | Algal growth, Mercury | — |
| Peaceful Valley Lake | Gasconade | C | Algal growth | — |
| Long Branch L. Lake | Macon | C | Algal growth | — |
| Monroe City Lake B Nr. Dam | Monroe | C | Algal growth | — |
| Hazel Creek Lk. Lake | Adair | C | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Clearwater Lake | Reynolds | C | Algal growth, Mercury | — |
| Mark Twain Lake | Monroe | C | Mercury | — |
| Longview Lake by Dam | Jackson | C | Mercury | — |
| Phillips Lake | Boone | C | Mercury | — |
| Rinquelin Trail Comm. Lake | Maries | C | Mercury | — |
| Bethel Lake | Boone | C | Algal growth | — |
| Marceline City Lake New Nr. Dam | Chariton | C | Algal growth | — |
| Happy Holler Lake | Andrew | C | Algal growth | — |
| Thomas Hill Lake @ Hwy T | Macon | C | Algal growth | — |
| Hunnewell Lake | Shelby | D | Mercury | — |
| Long Branch Lk. Lake | Macon | D | Algal growth | — |
| Hazel Creek Lk. East Fork Lake | Adair | D | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| L. Ste. Louise Lake | St. Charles | D | Mercury | — |
| Shepard Mountain Lake Intake | Iron | D | Algal growth | — |
| Deer Ridge Comm. Lake | Lewis | D | Algal growth, Mercury | — |
| Sugar Creek Lake | Randolph | D | Mercury | — |
| Ben Branch Lake by Dam | Osage | D | Mercury | — |
| Indian Hills Lake Nr. Dam | Crawford | D | Algal growth, Mercury | — |
| L. Ste. Louise Lake | St. Charles | D | Mercury | — |
| Pomme de Terre L. Central Arm Lake | Hickory | D | Algal growth | — |
| Indian Creek Lake | Livingston | D | Mercury | — |
| Longview L. Nr. Dam Lake | Jackson | D | Mercury | — |
| Frisco Lake | Phelps | D | Mercury | — |
| Pomme de Terre Lake | Hickory | D | Algal growth | — |
| Pomme de Terre Lake | Hickory | D | Algal growth | — |
| Sugar Creek Lake | Randolph | D | Mercury | — |
| Lake Springfield | Greene | D | Algal growth | — |
| Smithville Lake | Clay | D | Algal growth | — |
| Hazel Hill Lake by Dam | Johnson | D | Algal growth | — |
| Lake 36 | St. Charles | D | Mercury | — |
| Sunnen Lake | Washington | D | Algal growth | — |
| Macon City Lake | Macon | D | Algal growth | — |
| Pony Express Lake | DeKalb | D | Algal growth | — |
| Hamilton Lake | Caldwell | D | Algal growth | — |
| Buffalo Bill Lake Nr. Access | DeKalb | D | Algal growth, Mercury | — |
| Jamesport City Lake | Daviess | D | Algal growth | — |
| Lakewood Greenway Lake | Clay | D | Mercury | — |
| Harrison County Lake Intake | Harrison | D | Algal growth, Mercury | ✓ |
| Simpson Park Lake | St. Louis | D | Algal growth, Mercury | — |
| Binder Lake | Cole | D | Algal growth | — |
| Nodaway Lake | Nodaway | D | Algal growth | — |
| Manito Lake by Dam | Moniteau | D | Algal growth | — |
| Lake St. Louis | St. Charles | D | Algal growth | — |
| Lake Paho | Mercer | D | Mercury | — |
| Sugar Creek Lake North Arm | Randolph | D | Mercury | — |
| Simpson Park Lake | St. Louis | D | Algal growth, Mercury | — |
| Buffalo Bill Lake 0.4 Mi From Dam | DeKalb | D | Algal growth, Mercury | — |
| Belcher Branch Lake | Buchanan | D | Mercury | — |
| Pomme de Terre Lake | Hickory | D | Algal growth | — |
| Foxboro Lake | Franklin | D | Mercury | — |
| Lake 35 | St. Charles | D | Mercury | — |
| Lake of the Woods-Kc | Jackson | F | Mercury | — |
| Lake St. Louis by Dam | St. Charles | F | Algal growth | — |
| Blind Pony Lake | Saline | F | Algal growth | — |
| Little Dixie Lk. Lake | Callaway | F | Algal growth | — |
| Lamar City Lk. Nr. Dam Lake | Barton | F | Nutrients (phosphorus, nitrogen) | ✓ |
| Raintree Lake | Cass | F | Algal growth | — |
| Harrisonville City Lake | Cass | F | Algal growth | — |
| Lamar City Lk. W of Se 30th Ln Lake | Barton | F | Nutrients (phosphorus, nitrogen) | ✓ |
| Lamar City Lk. East Arm Lake | Barton | F | Nutrients (phosphorus, nitrogen) | ✓ |
| Lamar City Lk. South Arm Lake | Barton | F | Nutrients (phosphorus, nitrogen) | ✓ |
| Lamar City Lk. Up Northern Arm Lake | Barton | F | Nutrients (phosphorus, nitrogen) | ✓ |
| Cottontail Lake | Jackson | F | Mercury | — |
| Coot Lake | Jackson | F | Algal growth, Mercury | — |
| Mark Twain Lake | Monroe | F | Mercury | — |
| Harrison County Lake | Harrison | F | Algal growth, Mercury | ✓ |
| Pomme de Terre Lake | Hickory | F | Algal growth | — |
| Mckay Park Lake | Cole | F | Mercury | — |
| Harrisonville Lake | Cass | F | Algal growth | — |
| Edwin A Pape Lake | Lafayette | F | Algal growth | — |
| Elmwood Lake | Sullivan | F | Algal growth | — |
| Hemitite Lake | St. Francois | F | Algal growth | — |
| Vandalia Community Lake | Audrain | F | Algal growth | — |
| Cameron Lake Deep Site | DeKalb | F | Algal growth | — |
| Clearwater Lake @ Bluff View Park | Reynolds | F | Algal growth, Mercury | — |
| Dairy Farm Lake No.1 | Boone | F | Algal growth | — |
| Lake St. Louis Nr. Hwy 40 | St. Charles | F | Mercury | — |
| Drexel City Reservoir South Nr. Dam | Bates | F | Algal growth | — |
| Unionville Lake | Putnam | F | Algal growth | — |
| King Lake | DeKalb | F | Algal growth | — |
| Nell Lake | Jackson | F | Algal growth | — |
| Higginsville South Lake | Lafayette | F | Algal growth | — |
| Jackrabbit Lake | Jackson | F | Algal growth | — |
| Lamar City Lk. Nr. Upper End Lake | Barton | F | Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Luna | Cass | F | Algal growth | — |
| Chaumiere Lake | Clay | F | Mercury | — |
| North Lake | Cass | F | Algal growth | — |
| Spring Fork Lake | Pettis | F | Algal growth | ✓ |
| Montrose Lake | Henry | F | Algal growth | — |
| Sterling Price Lake | Chariton | F | Algal growth | — |
| Knox Village Lake | Jackson | F | Mercury | — |
| Crowder S.P. Lake | Grundy | F | Mercury | — |
| Cameron Lake Nr. Dam | DeKalb | F | Algal growth | — |
| Shelbyville Lake | Shelby | F | Algal growth | — |
| Mozingo Lake | Nodaway | F | Algal growth, Mercury | — |
| Holden City Lake Nr. Dam | Johnson | F | Mercury | — |
| Pomme de Terre Lake | Hickory | F | Algal growth | — |
| 34 Corner Blue Hole Lake | Mississippi | F | Mercury | — |
| Gopher Lake | Jackson | F | Algal growth | — |
| Cedar Lake | Boone | F | Algal growth | — |
| Jamesport Community Lake | Daviess | F | Algal growth | — |
| Bee Tree Lake | St. Louis | F | Mercury | — |
| Lake Taneycomo | Taney | F | Nutrients (phosphorus, nitrogen) | ✓ |
| Lewis Lake | Stoddard | F | Mercury | — |
| Lake of the Woods | Jackson | F | Mercury | — |
| Chaumiere Park Lake | Clay | F | Mercury | — |
| Catclaw Lake | Jackson | F | Algal growth | — |
| Memphis Lake No.1 | Scotland | F | Algal growth | — |
| Limpp Lake | Gentry | F | Algal growth | — |
| Perry City Lake | Ralls | F | Algal growth | — |
Frequently Asked Questions
How many lakes are impaired in Wisconsin?
145 of 388 graded Wisconsin lakes (37%) are listed as impaired in the most recent EPA ATTAINS reporting cycle. Of those, 133 are on the federal Clean Water Act §303(d) list and 14 have an approved Total Maximum Daily Load (TMDL) restoration plan.
What does Clean Water Act §303(d) mean?
Section 303(d) of the federal Clean Water Act requires every state to identify waters that don't meet water quality standards even after pollution control measures. Each listed water must then have a Total Maximum Daily Load (TMDL) developed — a plan that caps how much of each pollutant can enter the waterbody. The "303(d) list" is the impaired-waters list. The EPA reviews each state's list every two years.
What are the top causes of impairment in Wisconsin?
The most common causes flagged across Wisconsin's impaired lakes are: Algal growth (87 lakes); Mercury (58 lakes); Nutrients (phosphorus, nitrogen) (26 lakes). Mercury is widespread in fish tissue across the upper Midwest from atmospheric deposition. Nutrient impairment (phosphorus, nitrogen) typically reflects agricultural runoff and urban stormwater.
Can I swim in an impaired lake?
It depends on the cause of impairment. A lake impaired for "mercury in fish tissue" is generally safe to swim in — the warning is about long-term consumption of fish. A lake impaired for "pathogens" (E. coli) or "algal growth" may pose a swimming risk and often has a separate beach advisory. Check the cause categories listed for each lake below, and consult your state health department's beach monitoring program for current advisories.
Where does this impairment data come from?
Every impairment record on this page comes from the EPA's ATTAINS (Assessment and TMDL Tracking and Implementation System) public dataset, the federal repository of state-reported water quality assessments. EPA ATTAINS is published as GeoParquet files on the EPA Office of Water S3 bucket and refreshed several times per year. Causes and use-support codes follow EPA's standard taxonomy.
Data source
Impairment data from the EPA ATTAINS (Assessment and TMDL Tracking and Implementation System) public dataset. Assessment unit IDs are matched to LakeGrade waterbodies by name and proximity; some lakes may not appear here if their ATTAINS name doesn't match our naming convention. For an official query, consult Wisconsin's state water-quality agency.