Florence County Lake Quality
Wisconsin, 39 lakes, average grade B (Good)
There are 39 graded lakes in Florence County. The mix is varied enough that the county-level average tells you the broad strokes, not the choose-this-cabin specifics. The county-wide average lands at B — solid water quality with most lakes carrying clear summer transparency and low-to-moderate phosphorus.
Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. North Lake (A) is the cleanest in the county.
Quick Answers for Florence County
Planning a trip? Check special fishing regulations for North Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
DNR Reports (18)
Wisconsin DNR Fisheries Survey resources for lakes in Florence County. Showing 12 most recent — browse all reports →
- 2025Spread Eagle Chain panfish regulation assessment survey, 2025Panfish Survey · WI DNR · 2025 (PDF)
- 2024Brule River Flowage comprehensive/creel survey, 2024Comprehensive Survey · WI DNR · 2024 (PDF)
- 2024Fay Lake spring summary report, 2024Fisheries Survey · WI DNR · 2024 (PDF)
- 2024Halsey Lake comprehensive survey, 2024Comprehensive Survey · WI DNR · 2024 (PDF)
- 2024Patten Lake comprehensive survey, 2024Comprehensive Survey · WI DNR · 2024 (PDF)
- 2023Long Lake comprehensive survey, 2023Comprehensive Survey · WI DNR · 2023 (PDF)
- 2023Spread Eagle Chain comprehensive survey, 2023Comprehensive Survey · WI DNR · 2023 (PDF)
- 2022Bush Lake panfish netting survey, 2022Netting Survey · WI DNR · 2022 (PDF)
- 2022East Bass Lake shocking and netting survey, 2022Netting Survey · WI DNR · 2022 (PDF)
- 2022Ellwood Lake shocking and netting survey, 2022Netting Survey · WI DNR · 2022 (PDF)
- 2022Sand Lake shocking and netting survey, 2022Netting Survey · WI DNR · 2022 (PDF)
- 2022West Bass Lake shocking and netting survey, 2022Netting Survey · WI DNR · 2022 (PDF)
All Lakes in Florence County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | North Lake | A | 15 ft | 43 ft | - |
| 2 | Loon Lake | A | 16.8 ft | - | - |
| 3 | Sea Lion Lake | A | 21 ft | 82 ft | 11.5 µg/L |
| 4 | Keyes Lake | A | 21 ft | - | 11.1 µg/L |
| 5 | East Bass Lake | A | 17.8 ft | 42 ft | - |
| 6 | Sealion Lake | A | 25.6 ft | - | - |
| 7 | Lake Anna | A | 20.5 ft | 61 ft | - |
| 8 | Bass Lake | A | 12 ft | 16 ft | 11.6 µg/L |
| 9 | Ellwood Lake | A | 13 ft | 25 ft | 12 µg/L |
| 10 | Lost Lake | A | 10.6 ft | 45 ft | 13 µg/L |
| 11 | Porcupine Lake | A | 11 ft | 20 ft | 13 µg/L |
| 12 | Patten Lake | A | 10.1 ft | 52 ft | 15 µg/L |
| 13 | Frog Lake | B | 9.5 ft | - | 16.1 µg/L |
| 14 | Sand Lake | B | 12.2 ft | - | - |
| 15 | Sand Lake | B | 10.8 ft | 28 ft | - |
| 16 | Fay Lake | B | 7 ft | 10 ft | 15.5 µg/L |
| 17 | West Lake | B | 12 ft | 25 ft | - |
| 18 | Morgan Lake | B | 8.6 ft | 10 ft | 13 µg/L |
| 19 | Scout Lake | B | 14.2 ft | 26 ft | - |
| 20 | Long Lake -Spread Eagle Chain | B | 13.5 ft | - | - |
| 21 | Barrens Lake | B | 13.1 ft | - | - |
| 22 | North Lake -Spread Eagle Chain | B | 14.5 ft | - | - |
| 23 | Lake of Dreams | B | 10.2 ft | - | - |
| 24 | Middle Lake -Spread Eagle Chain | B | 14.4 ft | 54 ft | - |
| 25 | West Bass Lake | B | 14.4 ft | 19 ft | - |
| 26 | Long Lake | B | 7.2 ft | 21 ft | 25.2 µg/L |
| 27 | Halsey Lake | B | 6.2 ft | 10 ft | 18 µg/L |
| 28 | Reisner Lake | B | 6.5 ft | 5 ft | 18.1 µg/L |
| 29 | Mirror Lake | C | 8.5 ft | 13 ft | - |
| 30 | Emily Lake | C | 8.3 ft | - | - |
| 31 | Fisher Lake | C | 8.2 ft | - | - |
| 32 | West Lake -Spread Eagle Chain | C | 9.5 ft | 68 ft | - |
| 33 | Cosgrove Lake | C | 9.4 ft | - | - |
| 34 | Montgomery Lake | C | 6.8 ft | - | - |
| 35 | Seidel Lake | C | 7.3 ft | - | - |
| 36 | Little Cosgrove Lake | C | 8.6 ft | - | - |
| 37 | Twin Falls Flowage Us Twin Falls Dam Lake | C | 7 ft | 50 ft | - |
| 38 | Bush Lake | C | 8.1 ft | 18 ft | - |
| 39 | Fischer Lake | D | 5.5 ft | - | - |
Source: EPA National Aquatic Resource Surveys, 2026.