Belcourt Inlet Lake
Rolette County, North DakotaView mapDirections
ND DEQ publishes the water-quality measurements for Belcourt Inlet Lake. Here is what has been measured.
- Eutrophic
Belcourt Inlet Lake in Rolette County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 30.5 µg/L. Chlorophyll-a (algae): 10.7 µg/L.
Belcourt Inlet Lake is a productive, nutrient-rich eutrophic lake in Rolette County, North Dakota. Overall water quality is declining over recent sampling years. Compared to the 5 other monitored lakes in Rolette County, Belcourt Inlet Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2025-09-16. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Belcourt Inlet Lake is safe to swim in today is a call for the North Dakota Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Belcourt Inlet Lake
These are the measurements ND DEQ publishes for Belcourt Inlet Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 3.3 ft of visibility. Phosphorus 30.5 µg/L. Chlorophyll-a 10.7 µg/L. TSI 56.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 30.5µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 10.7µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 56 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Belcourt Inlet Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Belcourt Inlet Lake typically sits around 60°F at the surface in September. Summer average is about 69°F. Usually warmest in Jul (about 72°F) and coldest in May (about 57°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (57°F) to its warmest (72°F).
Typical surface water temperature by month, from 141 field readings (2010–2025) via the EPA Water Quality Portal. See the full Belcourt Inlet Lake water temperature breakdown →
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Stays near Belcourt Inlet Lake
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Fishing Belcourt Inlet Lake
Water Quality Trend: Worsening
Based on 5 years of monitoring (2021–2025).
Water clarity
Improving5 years
Phosphorus
Worsening+4.7 µg/L/yr5 years
Chlorophyll-a
Worsening+0.85 µg/L/yr4 years
Nearby Lakes in Rolette County
Frequently asked questions about Belcourt Inlet Lake
Where is Belcourt Inlet Lake?
- Belcourt Inlet Lake is a lake in Rolette County, North Dakota. Its water-quality measurements are published by ND DEQ and shown on this page as reported.
What is the water quality of Belcourt Inlet Lake?
- Belcourt Inlet Lake in Rolette County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 30.5 µg/L. Chlorophyll-a (algae): 10.7 µg/L.
Is Belcourt Inlet Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Belcourt Inlet Lake?
- Belcourt Inlet Lake typically sits around 60°F at the surface in September, from 141 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
Explore Belcourt Inlet Lake across LakeQuality
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Where this data comes from
212 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)
TURTLEMT212 samples · 2020–2025
Analytical methods
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.