Jamestown Reservoir
Stutsman County, WisconsinEutrophic
Jamestown Reservoir is a 17,427-acre productive, nutrient-rich eutrophic lake in Stutsman County, ND. Water quality is graded B based on 2 sampling years through 2025. Compared to the 6 other monitored lakes in Stutsman County, Jamestown Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2025-09-23. Grade methodology: LakeGrade methodology.
Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Moderate clarity, visible to about 7.2 ft. Chlorophyll-a: 8.5 µg/L. Trophic State Index: 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.2 ft | C |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 8.5 µg/L | B |
| Trophic State Index (TSI) | 50 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 17.4K acres |
Location
County Ranking
Ranked #3 of 7 lakes in Stutsman County
Cleaner Lakes Within 30 Miles
Jamestown Reservoir holds Grade B. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Stutsman County
More Wisconsin Lake Rankings
Other Grade B Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Jamestown Reservoir is a man-made reservoir impounded by the Jamestown Dam (completed 1954), built primarily for flood risk reduction on the JAMES RIVER; earth-type dam, 110 ft tall and 1,418 ft long.
- Surface area
- 17,427 ac
- Normal storage
- 35,535 ac-ft
- Max storage
- 379,636 ac-ft
- Drainage area
- 1,573.65 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
All listed purposes: Flood Risk Reduction;Irrigation.
Source: USACE National Inventory of Dams, NID ID ND00151 · Operator website
EPA Impairment Status
Jamestown Reservoir 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-10160001-002-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: 2025-09-23
Monitoring stations: 2