Stanley Reservoir
Mountrail County, WisconsinEutrophic
Stanley Reservoir is a 253-acre productive, nutrient-rich eutrophic lake in Mountrail County, ND. Water quality is graded D based on 2 sampling years through 2024. Compared to the 4 other monitored lakes in Mountrail County, Stanley Reservoir ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-10-03. Grade methodology: LakeGrade methodology.
Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 1.1 ft of visibility. Chlorophyll-a: 19.5 µg/L. Trophic State Index: 68.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.1 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 19.5 µg/L | C |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 253 acres |
Location
County Ranking
Ranked #5 of 5 lakes in Mountrail County
Cleaner Lakes Within 30 Miles
Stanley Reservoir holds Grade D. 5 nearby lakes hold higher grades.
- BGarlk1481dw LakeMcKenzie County · 23.2 mi · Two grade letters higher (D → B)
- CClearwater LakeMountrail County · 9.3 mi · Higher grade (D → C)
- CWhite Earth Dam LakeMountrail County · 19.6 mi · Higher grade (D → C)
- CPowers LakeMountrail County · 19.7 mi · Higher grade (D → C)
- CPowers Lake Dredge SiteMountrail County · 19.7 mi · Higher grade (D → C)
Nearby Lakes in Mountrail County
More Wisconsin Lake Rankings
Other Grade D Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Stanley Reservoir is a man-made reservoir impounded by the Stanley Dam (completed 1968), built primarily for water supply on the Little Knife River; earth-type dam, 21 ft tall and 860 ft long.
- Surface area
- 253 ac
- Normal storage
- 1,550 ac-ft
- Max storage
- 3,720 ac-ft
- Drainage area
- 22 sq mi
- Hazard class
- Low
- Owner
- City of Stanley
Source: USACE National Inventory of Dams, NID ID ND00192 · Operator website
EPA Impairment Status
Stanley 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-10110101-009-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: 2024-10-03
Monitoring stations: 1