Tama County Lake Quality
Iowa, 3 lakes, average grade F (Very Poor)
Tama County has 3 graded lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. 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. Otter Creek Lake (D) is the cleanest in the county.
Quick Answers for Tama County
Planning a trip? Check special fishing regulations for Otter Creek Lake — or check the official Iowa fishing regulations.
All Lakes in Tama County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Otter Creek Lake | D | 1.3 ft | - |
| 2 | Union Grove Lake | F | 1.6 ft | - |
| 3 | Casey Lake | F | 1.2 ft | - |
Other Counties in Iowa
See how Tama County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 15 states.
Where to stay near Tama County
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Source: EPA National Aquatic Resource Surveys, 2026.