Sweetwater Lake is a 48-acre highly nutrient-loaded hypereutrophic lake in Ramsey County, North Dakota. Water quality is graded D based on 3 sampling years through 2023. Overall water quality is improving over recent sampling years. The lake supports 3 documented fish species including Black Crappie, Yellow Perch, and Walleye. Compared to the 7 other monitored lakes in Ramsey County, Sweetwater Lake ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, North Dakota DNR, last sampled 2023-10-17. Grade methodology: LakeGrade methodology.
Watch Sweetwater Lake water quality
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 2.9 ft of visibility. Phosphorus level: 593 µg/L. Chlorophyll-a: 10.7 µg/L. Trophic State Index: 71.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.9 ft | F |
| Phosphorus | 593 µg/L | F |
| Chlorophyll-a (Algae) | 10.7 µg/L | C |
| Trophic State Index (TSI) | 71 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | 8 ft |
| Surface Area | 48 acres |
| Shoreline Length | 1.2 mi |
Where to stay near Sweetwater Lake
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Sweetwater Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +2.8 m/yr | 4 |
| Phosphorus | ↓ Declining | +200.74 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -42.12 µg/L/yr | 4 |
Water Temperature
Sweetwater Lake averages about 70°F at the surface in summer, usually warmest in Jul (about 73°F) and coldest in Feb (about 34°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 254 field readings (2010–2023) via the EPA Water Quality Portal. See the full Sweetwater Lake water temperature breakdown →
Location
County Ranking
Ranked #7 of 8 lakes in Ramsey County
Cleaner Lakes Within 30 Miles
Sweetwater Lake holds Grade D. 3 nearby lakes hold higher grades.
- CDevils LakeRamsey County · 10.5 mi · Higher grade (D → C)
- CDevils LakeBenson County · 18.3 mi · Higher grade (D → C)
- DPelican LakeRamsey County · 14.2 mi · Higher overall water quality score
Nearby Lakes in Ramsey County
Explore Sweetwater Lake across LakeGrade
Fish species and top-graded lakes across North Dakota
Fish species and best lakes in Ramsey County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Devils Lake Region area
Where to stay at North Dakota's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
North Dakota's cleanest and most-polluted lakes, ranked
More North Dakota Lake Rankings
Other Grade D Lakes in North Dakota
Hypereutrophic Lakes in North Dakota
More records, surveys & data sources
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Depth, fish, and access data from North Dakota Game & Fish
Most recent sample: 2023-10-17
Monitoring stations: 1