Sprague Lake is a 58-acre productive, nutrient-rich eutrophic lake in Sargent County, North Dakota with a maximum depth of 10 feet (8-foot average). Water quality is graded F based on 2 sampling years through 2020. The lake supports 2 documented fish species including Northern Pike and Walleye. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Sargent County, Sprague Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, North Dakota DNR, last sampled 2020-10-02. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 1.6 ft of visibility. Chlorophyll-a: 43.4 µg/L. Trophic State Index: 69.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 43.4 µg/L | F |
| Trophic State Index (TSI) | 69 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 9.5 ft |
| Average Depth | 7.6 ft |
| Surface Area | 58 acres |
| Shoreline Length | 3.4 mi |
| Public Access | Yes |
Where to stay near Sprague Lake
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Sprague Lake
Recreation & Access
Water Temperature
Sprague Lake averages about 67°F at the surface in summer, usually warmest in Jul (about 71°F) and coldest in Oct (about 49°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 15 field readings (2010–2020) via the EPA Water Quality Portal. See the full Sprague Lake water temperature breakdown →
Location
County Ranking
Ranked #3 of 3 lakes in Sargent County
Cleaner Lakes Within 30 Miles
Sprague Lake holds Grade F. 2 nearby lakes hold higher grades.
- CSilver LakeSargent County · 1.5 mi · Two grade letters higher (F → C)
- CAlkali LakeSargent County · 7.5 mi · Two grade letters higher (F → C)
Nearby Lakes in Sargent County
Explore Sprague Lake across LakeGrade
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Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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More records, surveys & data sources
Reservoir Info (USACE NID)
Sprague Lake is a man-made reservoir impounded by the Lake Mann Dam (completed 1965), built primarily for fish and wildlife pond on the Wild Rice River; earth-type dam, 9 ft tall and 784 ft long.
- Surface area
- 58 ac
- Normal storage
- 475 ac-ft
- Max storage
- 658 ac-ft
- Drainage area
- 0.18 sq mi
- Hazard class
- Low
- Owner
- US FISH AND WILDLIFE SERVICE
Source: USACE National Inventory of Dams, NID ID ND00900 · Operator website · Matched by proximity (0.8 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Lake size & watershed from HydroLAKES (HydroSHEDS)
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: 2020-10-02
Monitoring stations: 1