Mchugh Slough Lake
Nelson County, North DakotaView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- #4 of 4 in the county
- Limited data
Mchugh Slough Lake in Nelson County, North Dakota has a water quality grade of F (Algae-prone). Water clarity: 1.6 ft visibility. Phosphorus: 416 µg/L. Chlorophyll-a (algae): 88.7 µg/L.
- Clarity
- 1.6 ft
- Typical in September
- 58°F
- Type
- Hypereutrophic
- Phosphorus
- 416 µg/L
- Chlorophyll-a
- 88.7 µg/L
- Trend
- ↑ Improving
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Stays near Mchugh Slough Lake
Compare lakeside cabins, hotels, and vacation rentals near Mchugh Slough Lake in Nelson County, North Dakota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Mchugh Slough Lake are listed below.
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Mchugh Slough Lake is a highly nutrient-loaded hypereutrophic lake in Nelson County, North Dakota. Water quality is graded F based on 2 sampling years through 2023. Overall water quality is improving over recent sampling years. Compared to the 3 other monitored lakes in Nelson County, Mchugh Slough Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2023-10-16. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
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.
The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 1.6 ft of visibility. Phosphorus 416 µg/L. Chlorophyll-a 88.7 µg/L. TSI 79. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | Not graded |
| Phosphorus | 416 µg/L | Poor |
| Chlorophyll-a (Algae) | 88.7 µg/L | Poor |
| Trophic State Index (TSI) | 79 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Mchugh Slough Lake typically sits around 58°F at the surface in September. Summer average is about 70°F. Usually warmest in Jul (about 73°F) and coldest in Feb (about 35°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 295 field readings (2010–2023) via the EPA Water Quality Portal. See the full Mchugh Slough Lake water temperature breakdown →
Fishing Mchugh Slough Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +8.55 m/yr | 4 |
| Phosphorus | ↓ Declining | +95.93 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -27.7 µg/L/yr | 4 |
County Ranking
Ranked #4 of 4 lakes in Nelson County
Nearby Lakes in Nelson County
Frequently asked questions about Mchugh Slough Lake
Where is Mchugh Slough Lake?
- Mchugh Slough Lake is a lake in Nelson County, North Dakota. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Mchugh Slough Lake?
- Mchugh Slough Lake in Nelson County, North Dakota has a water quality grade of F (Algae-prone). Water clarity: 1.6 ft visibility. Phosphorus: 416 µg/L. Chlorophyll-a (algae): 88.7 µg/L.
Is Mchugh Slough Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Mchugh Slough Lake?
- Mchugh Slough Lake typically sits around 58°F at the surface in September, from 295 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Explore Mchugh Slough Lake across LakeQuality
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Where this data comes from
31 measurements from 1 monitoring station, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS North Dakota Water Science Center
USGS-ND31 samples · 2020–2023
Analytical methods
- P, wu, WCA, persulfate CF color
- Plant pigments, sonication & 445
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.