Jamestown Reservoir is a 17,427-acre productive, nutrient-rich eutrophic lake in Stutsman County, North Dakota with a maximum depth of 36 feet (14-foot average). Water quality is graded D based on 3 sampling years through 2023. Overall water quality is declining over recent sampling years. The lake supports 9 documented fish species including Northern Pike, Walleye, and Black Crappie. Public access is available with 3 public boat landings. Compared to the 6 other monitored lakes in Stutsman County, Jamestown Reservoir ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, North Dakota DNR, last sampled 2023-07-26. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Murky, only visible to about 6 ft. Phosphorus level: 560.5 µg/L. Chlorophyll-a: 17.6 µg/L. Trophic State Index: 69.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6 ft | D |
| Phosphorus | 560.5 µg/L | F |
| Chlorophyll-a (Algae) | 17.6 µg/L | C |
| Trophic State Index (TSI) | 69 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 36.2 ft |
| Average Depth | 14.2 ft |
| Surface Area | 17,427 acres |
| Shoreline Length | 31 mi |
| Public Access | Yes |
Where to stay near Jamestown Reservoir
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Jamestown Reservoir
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -8.647 m/yr | 6 |
| Phosphorus | ↓ Declining | +72.25 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -8.56 µg/L/yr | 5 |
Recreation & Access
Water Temperature
Jamestown Reservoir averages about 70°F at the surface in summer, usually warmest in Jul (about 74°F) and coldest in Oct (about 54°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 369 field readings (2012–2025) via the EPA Water Quality Portal. See the full Jamestown Reservoir water temperature breakdown →
Location
County Ranking
Ranked #6 of 7 lakes in Stutsman County
Cleaner Lakes Within 30 Miles
Jamestown Reservoir holds Grade D. 5 nearby lakes hold higher grades.
- ASpiritwood LakeStutsman County · 11.5 mi · Two grade letters higher (D → A)
- BJamestown ReservoirStutsman County · 3.2 mi · Two grade letters higher (D → B)
- CMoon LakeBarnes County · 26.4 mi · Higher grade (D → C)
- CBader LakeStutsman County · 27.9 mi · Higher grade (D → C)
- CHehn-Schaffer LakeStutsman County · 26.4 mi · Higher grade (D → C)
Nearby Lakes in Stutsman County
Explore Jamestown Reservoir across LakeGrade
Fish species and top-graded lakes across North Dakota
Fish species and best lakes in Stutsman County
Species activity outlook by water temperature and season
Where to stay at North Dakota's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
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More North Dakota Lake Rankings
Other Grade D Lakes in North Dakota
Eutrophic Lakes in North Dakota
Compare Jamestown Reservoir With Nearby Lakes
More records, surveys & data sources
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
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Jamestown Reservoir under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Jamestown City OfJamestown · 3.9 mi away · NPDES ND0023370MajorRecent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Depth, fish, and access data from North Dakota Game & Fish
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2023-07-26
Monitoring stations: 1