St Clair Lake
Becker County, Minnesota45 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for St Clair Lake. Here is what has been measured.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- zebra mussel
- 39 ft max depth
St Clair Lake in Becker County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4 ft visibility. Phosphorus: 50 µg/L. Chlorophyll-a (algae): 14.3 µg/L. Surface area: 45 acres.
St Clair Lake is a 45-acre productive, nutrient-rich eutrophic lake in Becker County, Minnesota with an estimated average depth of about 39 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 83 other monitored lakes in Becker County, St Clair Lake ranks #74 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-16. Methodology: how these readings are compared.
Swimming conditions
Readings onlyRecreation use not supported
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. St Clair Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether St Clair Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for St Clair Lake
These are the measurements Minnesota PCA publishes for St Clair Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4 ft. Phosphorus 50 µg/L. Chlorophyll-a 14.3 µg/L. TSI 58.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 50µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 14.3µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 58 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about St Clair Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
St Clair Lake typically sits around 67°F at the surface in September. Summer average is about 72°F. Usually warmest in Jul (about 75°F) and coldest in Sep (about 67°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (67°F) to its warmest (75°F).
Typical surface water temperature by month, from 223 field readings (2016–2025) via the EPA Water Quality Portal. See the full St Clair Lake water temperature breakdown →
Lake Details
Max depth
~39 ft est.
Surface area
45 acres
Public access
No
Listed by Minnesota PCA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for St Clair Lake.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Shoreline
2 mi
HydroLAKES / HydroSHEDS
Elevation
1,325 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Stays via Stay22
Stays near St Clair Lake
Compare lakeside cabins, hotels, and vacation rentals near St Clair Lake in Becker County, Minnesota — 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 readings cover nutrients and algae, not lodging. Cabins and rentals around St Clair Lake are listed below.
Top-rated places to stay near St Clair Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fishing St Clair Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Phosphorus
Improving-4.14 µg/L/yr6 years
Chlorophyll-a
Improving-0.86 µg/L/yr6 years
Reservoir Info (USACE NID)
St Clair Lake is a man-made reservoir impounded by the Long Lake (completed 1936), built primarily for recreation on the Pelican River-TR; gravity-type dam, 9 ft tall.
- Surface area
- 45 ac
- Normal storage
- 4,365 ac-ft
- Max storage
- 5,335 ac-ft
- Drainage area
- 3.2 sq mi
- Hazard class
- Low
- Owner
- MNDNR
Source: USACE National Inventory of Dams, NID ID MN00882 · Operator website · Matched by proximity (0.96 km)
EPA Impairment Status
St Clair Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN03-0382-00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of St Clair Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Detroit Lakes Water Reclamation FacilityDetroit Lakes · 1 mi away · NPDES MN0020192MajorRecent violation
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.
Nearby Lakes in Becker County
Frequently asked questions about St Clair Lake
Where is St Clair Lake?
- St Clair Lake is a lake in Becker County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of St Clair Lake?
- St Clair Lake in Becker County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4 ft visibility. Phosphorus: 50 µg/L. Chlorophyll-a (algae): 14.3 µg/L. Surface area: 45 acres.
Is St Clair Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. St Clair Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of St Clair Lake?
- St Clair Lake typically sits around 67°F at the surface in September, from 223 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.
How deep is St Clair Lake?
- No published bathymetric survey covers St Clair Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 39 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 45 acres.
Can I fish at St Clair Lake?
- Public access to St Clair Lake is listed as no on the lake record, so confirm before you make the trip. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore St Clair Lake across LakeQuality
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Where this data comes from
136 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA136 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (2)
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.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder