Cass County Lake Quality
Wisconsin, 5 lakes, average grade F (Very Poor)
Only 5 lakes in Cass 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. The county average is F — the most-stressed bracket in our rubric. Most monitored lakes here show persistent nutrient loading and algal pressure.
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. Raintree Lake (F) is the cleanest in the county.
Quick Answers for Cass County
Planning a trip? Check special fishing regulations for Raintree Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Cass County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Raintree Lake | F | 2.5 ft | - | 66.4 µg/L |
| 2 | Harrisonville City Lake | F | 1.9 ft | - | 78.5 µg/L |
| 3 | Harrisonville Lake | F | 1.1 ft | - | 69 µg/L |
| 4 | Lake Luna | F | 1.2 ft | - | 192.9 µg/L |
| 5 | North Lake | F | 1.6 ft | - | 152 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.