Belourt Outlet Lake
Rolette County, North Dakota827 acresView mapDirections
Clarity, phosphorus, and algae sit in the clean band for this region.
↑ up from D at the last regrade
- Eutrophic
- #4 of 6 in the county
Belourt Outlet Lake in Rolette County, North Dakota has a water quality grade of B (Good). Water clarity: 3 ft visibility. Phosphorus: 28 µg/L. Chlorophyll-a (algae): 12.5 µg/L. Surface area: 827 acres.
- Clarity
- 3 ft
- Typical in September
- 61°F
- Area
- 827 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
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Watch Belourt Outlet Lake’s letter
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Belourt Outlet Lake is a 827-acre productive, nutrient-rich eutrophic lake in Rolette County, North Dakota. Water quality is graded B based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. Compared to the 5 other monitored lakes in Rolette County, Belourt Outlet Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2025-09-16. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyBacteria A
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Based on E. coli testing, Belourt Outlet Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 9 samples across 3 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check North Dakota’s current beach and health-department advisories before swimming.
Water Quality Grade: B (Good)
Very murky, less than 3 ft of visibility. Phosphorus 28 µg/L. Chlorophyll-a 12.5 µg/L. TSI 56. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 28 µg/L | Good |
| Chlorophyll-a (Algae) | 12.5 µg/L | Good |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Belourt Outlet Lake typically sits around 61°F at the surface in September. Summer average is about 70°F. Usually warmest in Jul (about 73°F) and coldest in May (about 55°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 147 field readings (2010–2025) via the EPA Water Quality Portal. See the full Belourt Outlet Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 827 acres |
No bathymetric survey has been published for Belourt Outlet Lake, so its depth is not documented here.
Fishing Belourt Outlet Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.05 m/yr | 5 |
| Phosphorus | ↓ Declining | +3.25 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +0.3 µg/L/yr | 4 |
Reservoir Info (USACE NID)
Belourt Outlet Lake is a man-made reservoir impounded by the Belcourt Lake (completed 1930), built primarily for recreation on the Ox Creek; earth-type dam, 13 ft tall and 700 ft long.
- Surface area
- 827 ac
- Normal storage
- 5,651 ac-ft
- Max storage
- 9,159 ac-ft
- Drainage area
- 28.4 sq mi
- Hazard class
- High
- Owner
- BIA
All listed purposes: Recreation;Fish and Wildlife Pond;Water Supply.
Source: USACE National Inventory of Dams, NID ID ND00535 · Operator website · Matched by proximity (0.06 km)
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Belourt Outlet Lake under Clean Water Act (NPDES) discharge permits.
- Belcourt Public UtilitiesBelcourt · 2.8 mi away · NPDES ND0023647
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.
County Ranking
Ranked #4 of 6 lakes in Rolette County
Nearby Lakes With Higher Grades
Belourt Outlet Lake holds Grade B. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Rolette County
Frequently asked questions about Belourt Outlet Lake
Where is Belourt Outlet Lake?
- Belourt Outlet Lake is a lake in Rolette County, North Dakota. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Belourt Outlet Lake?
- Belourt Outlet Lake in Rolette County, North Dakota has a water quality grade of B (Good). Water clarity: 3 ft visibility. Phosphorus: 28 µg/L. Chlorophyll-a (algae): 12.5 µg/L. Surface area: 827 acres.
Is Belourt Outlet Lake safe to swim in?
- Based on E. coli testing, Belourt Outlet Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 9 samples across 3 seasons. That works out to a bacteria swim-safety grade of A — a historical summary of past testing, not a current reading. Belourt Outlet Lake has a water quality grade of B (Good). Bacteria levels can spike quickly after heavy rain, so always check North Dakota's current beach and health-department advisories before you swim.
What is the water temperature of Belourt Outlet Lake?
- Belourt Outlet Lake typically sits around 61°F at the surface in September, from 147 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
Explore Belourt Outlet Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
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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Where this data comes from
217 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Turtle Mountain Environmental Office (Tribal)
TURTLEMT217 samples · 2020–2025
Analytical methods
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Depth, fish, and access data from North Dakota Game & Fish