Whitman Dam Lake is a 143-acre mesotrophic lake in Nelson County, North Dakota with a maximum depth of 21 feet (9-foot average). Water quality is graded B based on 1 sampling years through 2025. The lake supports 5 documented fish species including Northern Pike, Walleye, and Yellow Perch. Public access is available with 1 public boat landing. Compared to the 8 other monitored lakes in Nelson County, Whitman Dam Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, North Dakota DNR, last sampled 2025-10-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Good clarity, visible to about 12 ft. Trophic State Index: 41.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 20.8 ft |
| Average Depth | 8.9 ft |
| Surface Area | 143 acres |
| Shoreline Length | 7.4 mi |
| Public Access | Yes |
Where to stay near Whitman Dam Lake
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Whitman Dam Lake
Recreation & Access
Water Temperature
Whitman Dam Lake averages about 68°F at the surface in summer, usually warmest in Jun (about 68°F) and coldest in Oct (about 46°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 17 field readings (2016–2025) via the EPA Water Quality Portal. See the full Whitman Dam Lake water temperature breakdown →
Location
County Ranking
Ranked #1 of 9 lakes in Nelson County
Nearby Lakes in Nelson County
Explore Whitman Dam Lake across LakeGrade
Fish species and top-graded lakes across North Dakota
Fish species and best lakes in Nelson 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
Moderate nutrients, good water quality
North Dakota's cleanest and most-polluted lakes, ranked
More North Dakota Lake Rankings
Other Grade B Lakes in North Dakota
Mesotrophic Lakes in North Dakota
More records, surveys & data sources
Reservoir Info (USACE NID)
Whitman Dam Lake is a man-made reservoir impounded by the Whitman Dam (completed 1965), built primarily for flood risk reduction on the Middle Branch Forest River; earth-type dam, 49 ft tall and 1,200 ft long.
- Surface area
- 143.4 ac
- Normal storage
- 1,355.5 ac-ft
- Max storage
- 9,364 ac-ft
- Drainage area
- 84.7 sq mi
- Hazard class
- Significant
- Owner
- Walsh County WRB
All listed purposes: Flood Risk Reduction;Recreation.
Source: USACE National Inventory of Dams, NID ID ND00207 · Operator website
EPA Impairment Status
Whitman Dam 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-09020308-002-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
Depth, fish, and access data from North Dakota Game & Fish
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2025-10-22
Monitoring stations: 1