Cass County Lake Quality
North Dakota, 1 lakes, average grade D (Poor)
Only 1 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-wide average grade is D — water quality issues are persistent across most of the monitored basins. 0 lakes fall into the F bracket outright.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Brewer Lake (D); the most-stressed is Brewer Lake (D).
Quick Answers for Cass County
Planning a trip? Check special fishing regulations for Brewer Lake, whether the fish are safe to eat, and the best times to fish — or check the official North Dakota fishing regulations.
All Lakes in Cass County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Brewer Lake | D | 4.3 ft | 30.9 ft | - |
Other Counties in North Dakota
See how Cass 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 Cass County
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Source: EPA National Aquatic Resource Surveys, 2026.