Portage County Lake Quality
Wisconsin, 29 lakes, average grade A (Excellent)
Portage County's 29 graded lakes fall in the moderate-density bracket for Wisconsin. The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. The county's average grade is A — among the cleanest in Wisconsin. 22 lakes pull an A on their own, and almost none fall into the D or F brackets.
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. Sunset Lake (A) is the cleanest in the county.
Quick Answers for Portage County
Planning a trip? Check special fishing regulations for Sunset Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
DNR Reports (4)
Wisconsin DNR Fisheries Survey resources for lakes in Portage County. browse all reports →
- 2025Thomas Lake spring shocking, 2025Spring Shocking Survey · WI DNR · 2025 (PDF)
- 2024Sunset Lake spring shocking, 2024Spring Shocking Survey · WI DNR · 2024 (PDF)
- 2023Stevens Point Flowage comprehensive survey, 2023Comprehensive Survey · WI DNR · 2023 (PDF)
- 2022Collins Lake spring shocking, 2022Spring Shocking Survey · WI DNR · 2022 (PDF)
All Lakes in Portage County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Sunset Lake | A | 41 ft | 55 ft | 12 µg/L |
| 2 | Bear Lake | A | 42.7 ft | 28 ft | - |
| 3 | Lake Emily | A | 36.1 ft | 35 ft | 16.9 µg/L |
| 4 | Pickerel Lake | A | 32.8 ft | - | - |
| 5 | Wolf Lake | A | 27.9 ft | 17 ft | - |
| 6 | Lake Helen | A | 25.4 ft | 20 ft | 19.3 µg/L |
| 7 | South Twin Lake | A | 16.4 ft | 9 ft | - |
| 8 | Lake Susan | A | 26.2 ft | 24 ft | - |
| 9 | Adams Lake | A | 23.8 ft | 44 ft | - |
| 10 | Ebert Lake | A | 68.9 ft | - | - |
| 11 | Rinehart Lake | A | 57.4 ft | - | 13.8 µg/L |
| 12 | Glisezinski Lake | A | 29.5 ft | - | 16.4 µg/L |
| 13 | Unnamed Lake | A | - | - | 6.5 µg/L |
| 14 | Lake Lime | A | 34.5 ft | 29 ft | - |
| 15 | Onland Lake | A | 34.5 ft | 28 ft | 11.1 µg/L |
| 16 | Fountain Lake | A | 72.2 ft | - | - |
| 17 | Springville Pond | A | 29.5 ft | - | 18.8 µg/L |
| 18 | Thomas Lake | A | 49.2 ft | 28 ft | - |
| 19 | Lake Helen | A | - | 20 ft | 16.1 µg/L |
| 20 | Spring Lake | A | 27.5 ft | 42 ft | 29.9 µg/L |
| 21 | Collins Lake | A | 19.4 ft | 56 ft | 20.6 µg/L |
| 22 | Tree Lake | A | 24 ft | 33 ft | 20.1 µg/L |
| 23 | Mcdill Pond | B | 16.4 ft | 19 ft | 34.2 µg/L |
| 24 | Lake Ell Lake | B | 11.5 ft | 20 ft | - |
| 25 | Lake Pacawa | B | 14.8 ft | 12 ft | - |
| 26 | Joanis Lake | B | - | - | 23 µg/L |
| 27 | Jordan Pond | B | 11.5 ft | 7 ft | 35.6 µg/L |
| 28 | Amherst Millpond | C | - | 7 ft | 31.3 µg/L |
| 29 | Culvert on Lake Helen | D | - | - | 87.1 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.