Devils Lake
Ramsey County, WisconsinEutrophic
Devils Lake is a 140,000-acre productive, nutrient-rich eutrophic lake in Ramsey County, ND. Water quality is graded C based on 2 sampling years through 2025. Compared to the 7 other monitored lakes in Ramsey County, Devils Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2025-10-09. Grade methodology: LakeGrade methodology.
Swimming Safety
Swim with caution, moderate algae may be present
Water Quality Grade: C, Fair
Murky, only visible to about 5.2 ft. Chlorophyll-a: 17 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.2 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 17 µg/L | C |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 140.0K acres |
Location
County Ranking
Ranked #1 of 8 lakes in Ramsey County
Nearby Lakes in Ramsey County
More Wisconsin Lake Rankings
Other Grade C Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Devils Lake is a man-made reservoir impounded by the Spirit Lake Jetty 1 (completed 1997), built primarily for flood risk reduction on the Sheyenne River -TR; earth-type dam, 22 ft tall and 2,145 ft long.
- Surface area
- 140,000 ac
- Normal storage
- 2,166,418 ac-ft
- Max storage
- 3,341,785 ac-ft
- Drainage area
- 3,322 sq mi
- Hazard class
- High
- Owner
- BIA
All listed purposes: Flood Risk Reduction;Other;Fish and Wildlife Pond;Recreation.
Source: USACE National Inventory of Dams, NID ID ND01090 · Operator website
EPA Impairment Status
Devils Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit ND-09020201-006-L_00 · Official waterbody report
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-10-09
Monitoring stations: 3