
Impaired Lakes in Florida
244 of 2,012 measured Florida lakes (12%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 146 have an approved TMDL restoration plan.
Top Causes of Impairment in Florida
Reading the Florida impairment landscape
244 of Florida's 2,012 tracked lakes carry impaired-waters listings — 12%. That's a meaningful minority worth checking before specific trips, particularly for swimming, fishing, or drinking-water source identification. Most Florida lakes are unimpaired; the impaired set tends to concentrate in agricultural, post-industrial, or high-development watersheds rather than being randomly distributed.
The leading impairment category in Florida is Nutrients (phosphorus, nitrogen) — nutrient enrichment, typically from agricultural fertilizer runoff, septic discharge, or stormwater carrying lawn-care residue. Nutrient-impaired lakes can still be safe for contact recreation in many conditions, but they're prone to algal blooms (including potentially toxic cyanobacteria) during warm-water periods. Check the state's beach-monitoring or harmful-algal-bloom dashboard before swimming on nutrient-impaired waters in summer.
Impaired-waters listings come from the state environmental agency's §303(d) submission to EPA, refreshed on a roughly 2-year cycle. A listed lake stays on the list until either a TMDL is established and the cleanup completes, or subsequent monitoring shows the pollutant concentrations no longer exceed water-quality standards. The list below reflects the most recent available Florida submission to the EPA Assessment, Total Maximum Daily Load Tracking and Implementation System (ATTAINS) dataset.
All 244 EPA-Listed Impaired Lakes in Florida
| Lake | County | Causes | TMDL |
|---|---|---|---|
| Spring Lake | Seminole | Nutrients (phosphorus, nitrogen) | ✓ |
| Lake-Emma | Lake | Mercury | ✓ |
| Bear Gully Lake | Seminole | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake-Louisa | Lake | Mercury, pH / acidity | ✓ |
| Lake-Joanna | Lake | Mercury | ✓ |
| Lake Glenada | Highlands | Algal growth | ✓ |
| Lake Druid | Orange | Oxygen depletion (low DO) | — |
| Horseshoe North Lake | Seminole | pH / acidity | — |
| Lake-Dorr | Lake | Mercury | ✓ |
| Park Lake | Orange | Impaired biota (cause unknown) | — |
| Lake-Florence | Lake | Algal growth, Impaired biota (cause unknown) | — |
| Little Lake Jackson | Highlands | Algal growth, Impaired biota (cause unknown) | — |
| Lake-Little Harris | Lake | Nutrients (phosphorus, nitrogen) | ✓ |
| Bass Lake | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Buck Lake | Seminole | pH / acidity | — |
| Buck Lake | Highlands | Nutrients (phosphorus, nitrogen) | — |
| Little Fish Lake | Orange | Mercury | ✓ |
| Lake-Bear | Lake | pH / acidity | — |
| Lake-Lorraine | Lake | Oxygen depletion (low DO) | — |
| Lake Iamonia | Leon | Mercury, Oxygen depletion (low DO), pH / acidity | ✓ |
| Lake-Eustis | Lake | Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Bay Lake | Orange | Nutrients (phosphorus, nitrogen) | ✓ |
| Down Lake | Orange | Mercury | ✓ |
| Griffin Lake | Lake | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake-Wildcat | Lake | Mercury | ✓ |
| Tanner Lake | Orange | pH / acidity | — |
| Louise Lake | Orange | Mercury | ✓ |
| Palm Lake | Orange | pH / acidity | — |
| Lake Francis | Highlands | Algal growth | — |
| Carr Lake | Leon | pH / acidity | — |
| Yankee Lake | Seminole | pH / acidity | — |
| Starke Lake | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Carlton Lake | Orange | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Apthorpe | Highlands | Mercury | ✓ |
| Lake Brantley | Seminole | Mercury | ✓ |
| Lake Tarpon | Pinellas | Algal growth, Impaired biota (cause unknown), Mercury | ✓ |
| Weston Lake | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Bearhead Lake | Orange | Impaired biota (cause unknown) | — |
| Pocket Lake | Orange | Mercury | ✓ |
| Marshall Lake | Orange | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Lovely Lake | Orange | Algal growth | — |
| Mary Jane Lake | Orange | Mercury, Metals (other than mercury), pH / acidity | ✓ |
| Sheen Lake | Orange | Mercury | ✓ |
| Dias Lake | Volusia | Mercury | ✓ |
| Lake Griffin | Lake | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Hart Lake | Orange | Mercury, Metals (other than mercury), pH / acidity | ✓ |
| Amory Lake | Seminole | Impaired biota (cause unknown), Oxygen depletion (low DO) | — |
| Cascade Lake | Leon | Metals (other than mercury), pH / acidity | — |
| Mccoy Lake | Orange | Impaired biota (cause unknown) | — |
| Davis Lake | Citrus | Mercury, Oxygen depletion (low DO) | ✓ |
| Lake Anderson | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Nan Lake | Orange | Impaired biota (cause unknown) | — |
| Dosson Lake | Hillsborough | Impaired biota (cause unknown) | — |
| Prima Vista Lake | Orange | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | — |
| Garden Lake | Seminole | Impaired biota (cause unknown) | — |
| Minneola Lake | Lake | Impaired biota (cause unknown), Mercury | ✓ |
| Bumby Lake | Orange | Algal growth, Metals (other than mercury), Nutrients (phosphorus, nitrogen) | ✓ |
| Pearl Lake | Orange | pH / acidity | — |
| Pearl Lake | Orange | Impaired biota (cause unknown) | — |
| Beauclair Lake | Lake | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Whitetrout Lake | Hillsborough | Impaired biota (cause unknown) | — |
| Bear Lake | Seminole | Mercury | ✓ |
| Lake Marion | Seminole | Impaired biota (cause unknown) | — |
| Lake Hiawatha | Leon | pH / acidity | — |
| Lake Arnold | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Jackson | Leon | Mercury, Oxygen depletion (low DO), pH / acidity | ✓ |
| Deforest Lake | Seminole | Oxygen depletion (low DO) | — |
| Irma Lake | Orange | pH / acidity | — |
| Lake-Yale | Lake | Mercury, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Winyah | Orange | Algal growth, Impaired biota (cause unknown) | — |
| Lake Seminary | Seminole | pH / acidity | — |
| Lake Ann | Seminole | Impaired biota (cause unknown) | — |
| Lindsey Lake | Hernando | Oxygen depletion (low DO) | — |
| Lake Silver | Orange | Nutrients (phosphorus, nitrogen) | ✓ |
| Butler Lake | Orange | Mercury | ✓ |
| Lake Giles | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Concord | Seminole | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Concord | Orange | Impaired biota (cause unknown) | — |
| Sylvan Lake | Seminole | Mercury, pH / acidity | ✓ |
| Lake Piney-Z | Leon | Algal growth, Mercury, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Mills | Seminole | pH / acidity | — |
| Bessie Lake | Orange | Mercury | ✓ |
| Lake Glona | Lake | Mercury | ✓ |
| Lake-Minnehaha | Lake | Mercury | ✓ |
| Tyler Lake | Orange | Impaired biota (cause unknown) | — |
| Lake Weeks | Leon | pH / acidity | — |
| Lake Proctor | Seminole | Oxygen depletion (low DO) | — |
| Lake Harris | Lake | Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Linda | Pasco | Impaired biota (cause unknown) | — |
| Lake Annie | Highlands | Mercury, pH / acidity | ✓ |
| Lake Lotela | Highlands | Algal growth, Mercury | ✓ |
| Lake Lucien | Orange | Mercury | ✓ |
| Cooter Lake | Citrus | Impaired biota (cause unknown), Oxygen depletion (low DO) | — |
| Henderson Lake | Citrus | Mercury | ✓ |
| Lake Letta | Highlands | Impaired biota (cause unknown) | — |
| Munson Lake | Leon | Algal growth, Metals (other than mercury), Nutrients (phosphorus, nitrogen) | ✓ |
| Johns Lake | Orange | Impaired biota (cause unknown), Mercury | ✓ |
| Tussock Lake | Citrus | Oxygen depletion (low DO) | — |
| Bird Lake | Hillsborough | Impaired biota (cause unknown) | — |
| Lake Henry | Highlands | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake-Umatilla | Lake | Impaired biota (cause unknown) | — |
| Lake Smart | Polk | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Red Water Lake | Highlands | Algal growth, Nutrients (phosphorus, nitrogen), pH / acidity | ✓ |
| Blue Lake | Highlands | Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | — |
| Cherry Lake | Madison | Algal growth, Mercury | ✓ |
| Dora Lake | Lake | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Mckay Creek Lake | Pinellas | Noxious aquatic plants, Pathogens (E. coli, fecal) | ✓ |
| Lake Tom John | Leon | Algal growth, Mercury, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake of the Woods | Seminole | pH / acidity | — |
| Sandy Lake | Orange | Nutrients (phosphorus, nitrogen) | — |
| Lotta Lake | Orange | Algal growth, Impaired biota (cause unknown) | ✓ |
| Roberts Lake | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Crystal Lake | Polk | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Queens Mirror Lake | Seminole | Algal growth | — |
| Tilden Lake | Orange | Impaired biota (cause unknown) | — |
| Huckleberry Lake | Highlands | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Eola | Orange | Algal growth | — |
| Lake Howell | Seminole | Impaired biota (cause unknown) | — |
| Lake Terrace | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Buffum | Polk | Impaired biota (cause unknown), Mercury | ✓ |
| Lake Tarpon Canal | Pinellas | Algal growth, Mercury | ✓ |
| Lake Rochelle | Polk | Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Alligator Lake | Columbia | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Maggiore | Pinellas | Algal growth, Nutrients (phosphorus, nitrogen), Salinity / chlorides | — |
| Lake Beardall | Orange | Nutrients (phosphorus, nitrogen) | — |
| Alligator Lake | Pinellas | Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | — |
| Irvin Lake | Hernando | Impaired biota (cause unknown) | — |
| Lake Monroe | Volusia | Algal growth, Impaired biota (cause unknown), Mercury +2 more | ✓ |
| Lake of the Woods | Orange | Nutrients (phosphorus, nitrogen) | — |
| Lake Wade | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Tiger Lake | Polk | Mercury, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Richmond | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Seminole | Pinellas | Algal growth, Nutrients (phosphorus, nitrogen), pH / acidity | — |
| Lake Seminole | Pinellas | Algal growth, Nutrients (phosphorus, nitrogen), pH / acidity | — |
| Lake Fran | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Hancock | Polk | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) +1 more | ✓ |
| Lake Okeechobee | Palm Beach | Mercury, Metals (other than mercury), Nutrients (phosphorus, nitrogen) +1 more | ✓ |
| Lake Davis | Orange | Algal growth, Nutrients (phosphorus, nitrogen), Pathogens (E. coli, fecal) | ✓ |
| Kelly Lake | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Lawsona | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Weldona | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Apopka Lake | Orange | Algal growth, Nutrients (phosphorus, nitrogen), Pesticides | ✓ |
| Lake Seminole | Pinellas | Algal growth, Nutrients (phosphorus, nitrogen), pH / acidity | — |
| Lake Talquin West | Gadsden | Algal growth, Mercury, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Adair | Orange | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Dead Lake | Flagler | Mercury | ✓ |
| Lake Trafford | Collier | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Kasey Lake | Orange | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) +1 more | ✓ |
| Fox Lake | Brevard | Mercury | ✓ |
| Kinsale Lake | Leon | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Condel Lake | Orange | Algal growth, Metals (other than mercury), Nutrients (phosphorus, nitrogen) +1 more | ✓ |
| Lake Haines | Polk | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Crago | Polk | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Tallavana Lake | Gadsden | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) +2 more | ✓ |
| Doctor'S Lake | Clay | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Doctor'S Lake | Clay | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Thonotosassa | Hillsborough | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Istokpoga | Highlands | Algal growth, Mercury, Nutrients (phosphorus, nitrogen) +1 more | ✓ |
| Doctors Lake | Clay | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Blue Cove Lake | Marion | Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | — |
| Lake Vedra | St. Johns | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Denham Lake | Lake | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Olive | Orange | Impaired biota (cause unknown) | — |
| Lake Norris | Lake | Mercury, Metals (other than mercury) | ✓ |
| Sweetwater Creek Lake | Seminole | Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | — |
| Alligator Creek Lake | Pinellas | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Mirror Lake | Lake | pH / acidity | — |
| Lake Francis | Madison | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Wauberg | Alachua | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Joanna Lake | Lake | Mercury | ✓ |
| Tank Lake | Hernando | Oxygen depletion (low DO) | — |
| Lake Hunter | Polk | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Gap Lake | Washington | Mercury | ✓ |
| James Lake | Hillsborough | Impaired biota (cause unknown) | — |
| Lake Grassy | Highlands | Mercury | ✓ |
| Lake Marion | Polk | Algal growth, Mercury, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Jackson | Walton | Mercury | ✓ |
| Lake Jackson | Highlands | Impaired biota (cause unknown), Mercury | ✓ |
| Lake Virginia | Hillsborough | Impaired biota (cause unknown) | — |
| Lake Eden | St. Lucie | pH / acidity | — |
| Lake Deer | Polk | Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Clinch | Polk | Algal growth, Mercury, Nutrients (phosphorus, nitrogen) +1 more | ✓ |
| Isabell Lake | Polk | pH / acidity | — |
| Lake Garfield | Polk | Mercury | ✓ |
| Henderson Lake | Citrus | Mercury | ✓ |
| Lake Ariana | Polk | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lochloosa Lake | Alachua | Nutrients (phosphorus, nitrogen) | ✓ |
| Yale Lake | Lake | Mercury, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Ida | Palm Beach | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Holden | Orange | Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Copeland | Orange | Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | — |
| Lake Thomas | Pasco | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Rowell | Bradford | Impaired biota (cause unknown), Mercury, pH / acidity | ✓ |
| Lake Sebring | Highlands | Mercury | ✓ |
| Persimmon Lake | Highlands | Algal growth, Nutrients (phosphorus, nitrogen), pH / acidity | ✓ |
| Lake Minnehaha | Lake | Mercury | ✓ |
| Newnan'S Lake | Alachua | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Clay | Highlands | Mercury | ✓ |
| Lake Disston | Flagler | Mercury, Metals (other than mercury), pH / acidity | ✓ |
| Lake Washington | Brevard | Impaired biota (cause unknown), Mercury | ✓ |
| Harris Lake | Lake | Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Carrie | Highlands | Impaired biota (cause unknown) | — |
| Lake Pickett | Orange | Mercury, pH / acidity | ✓ |
| Lake Conine | Polk | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Compass Lake | Jackson | Mercury | ✓ |
| Lake Manatee | Manatee | Impaired biota (cause unknown), Mercury, Pathogens (E. coli, fecal) | ✓ |
| Lake Hollingsworth | Polk | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Alligator Lake | Osceola | Mercury | ✓ |
| Lake Placid | Highlands | Algal growth, Mercury | ✓ |
| Lake Juliana | Polk | Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Drawdy | Orange | pH / acidity | — |
| Lake Alfred | Polk | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Weohyakapka | Polk | Mercury, pH / acidity | ✓ |
| Lake Worrell | Pasco | Oxygen depletion (low DO) | — |
| Gooseneck Lake | Pasco | Oxygen depletion (low DO) | — |
| Ashby Lake | Volusia | Impaired biota (cause unknown), Mercury | ✓ |
| Lake Conway | Orange | Mercury | ✓ |
| Newnans Lake | Alachua | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Sampson | Bradford | Mercury, pH / acidity | ✓ |
| Spring Garden Lake | Volusia | Mercury | ✓ |
| Lake Gibson | Polk | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Petty Gulf Lake | Leon | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | — |
| Cannon Lake | Polk | Algal growth, Nutrients (phosphorus, nitrogen), pH / acidity | ✓ |
| Minnehaha Lake | Lake | Mercury | ✓ |
| Lake Allen | Hillsborough | Impaired biota (cause unknown) | — |
| Lake Parker | Polk | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | ✓ |
| Dexter Lake | Volusia | Mercury | ✓ |
| Lake Santa Fe | Alachua | Mercury, pH / acidity | ✓ |
| Big Sand Lake | Orange | Mercury, Metals (other than mercury) | ✓ |
| Lake Rosalie | Polk | Impaired biota (cause unknown) | — |
| Lake Earl | Okaloosa | Mercury | ✓ |
| Lake Bonny | Polk | Algal growth, Nutrients (phosphorus, nitrogen), pH / acidity | ✓ |
| Lake Rousseau | Citrus | Mercury | ✓ |
| Lake Broward | Putnam | Mercury | ✓ |
| Lake Okeechobee | Palm Beach | Mercury, Nutrients (phosphorus, nitrogen), Turbidity | ✓ |
| Lake Kanturk | Leon | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Kanturk | Leon | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Kanturk Lake | Leon | Algal growth, Nutrients (phosphorus, nitrogen) | — |
| Lake Clarke | Palm Beach | Algal growth, Impaired biota (cause unknown), Nutrients (phosphorus, nitrogen) | — |
| Alford Arm Tributary Lake | Leon | Oxygen depletion (low DO) | — |
| Ella Lake | Lake | Mercury | ✓ |
| Lake Bryant | Marion | Mercury | ✓ |
| Georges Lake | Putnam | Mercury, pH / acidity | ✓ |
| Ella Lake | Lake | Mercury | ✓ |
Frequently Asked Questions
How many lakes are impaired in Florida?
244 of 2,012 measured Florida lakes (12%) are listed as impaired in the most recent EPA ATTAINS reporting cycle. Of those, 130 are on the federal Clean Water Act §303(d) list and 146 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 Florida?
The most common causes flagged across Florida's impaired lakes are: Nutrients (phosphorus, nitrogen) (107 lakes); Algal growth (95 lakes); Mercury (83 lakes); Impaired biota (cause unknown) (63 lakes); pH / acidity (42 lakes); Oxygen depletion (low DO) (17 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.
More on impaired waters
What it means when a lake is listed as impaired, why mercury is the most common reason, and why a listed lake can still be clear water with favourable readings.
Why states issue fish-consumption advisories, which contaminants — mercury, PCBs, PFAS — drive them, and how to eat the fish you catch more safely.
How phosphorus and nutrient runoff drive algae growth and turn lakes green, where the nutrients come from, and what it means for a lake’s readings.
Which lakes are actually improving: multi-year EPA monitoring trends, the named recoveries still in progress, and what it takes to move the readings.
Data source
Impairment data from the EPA ATTAINS (Assessment and TMDL Tracking and Implementation System) public dataset. Assessment unit IDs are matched to LakeQuality lakes 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 Florida's state water-quality agency.