Grant County Lake Quality
Wisconsin, 3 lakes, average grade C (Fair)
Only 3 lakes in Grant County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. Grant County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.
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. Jones Slough Lake (B) is the cleanest in the county.
Quick Answers for Grant County
Planning a trip? Check special fishing regulations for Jones Slough Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Grant County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Jones Slough Lake | B | 16.1 ft | - | 31 µg/L |
| 2 | Rice Lake | B | 15.1 ft | - | 66.6 µg/L |
| 3 | Unknown Lake | D | 7.9 ft | - | 135.5 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.