Beaulieu Lake
Beaulieu Lake in Mahnomen County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.3 ft visibility. Phosphorus: 90 µg/L. Chlorophyll-a (algae): 55.8 µg/L. Surface area: 300 acres.
- Clarity
- 1.3 ft
- Mean depth
- ~7 ft est.
- Area
- 300 acres
- Public access
- No
Next lake in Mahnomen County
Why Beaulieu Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Beaulieu Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Beaulieu Lake is a 300-acre lake in Mahnomen County, Minnesota with an estimated average depth of about 7 feet. Limited fish-species data available. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-08-08. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Beaulieu Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 1.3 ft of visibility. Phosphorus level: 90 µg/L. Chlorophyll-a: 55.8 µg/L. Trophic State Index: 71.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | Not graded |
| Phosphorus | 90 µg/L | Not graded |
| Chlorophyll-a (Algae) | 55.8 µg/L | Not graded |
| Trophic State Index (TSI) | 71 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Beaulieu Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~7 ft est. |
| Surface Area | 300 acres |
| Public Access | No |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Beaulieu Lake.
Lake Size & Watershed
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.
Fishing Beaulieu Lake
Reservoir Info (USACE NID)
Beaulieu Lake is a man-made reservoir impounded by the Beaulieu Lake (completed 1922), built primarily for fish and wildlife pond on the MARSH CREEK - TR; gravity-type dam, 10 ft tall and 300 ft long.
- Surface area
- 300 ac
- Normal storage
- 1,128 ac-ft
- Drainage area
- 43.6 sq mi
- Hazard class
- Undetermined
- Owner
- USFWS
Source: USACE National Inventory of Dams, NID ID MN00216 · Operator website
Graded lakes near Beaulieu Lake
Beaulieu Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Mahnomen County
Frequently asked questions about Beaulieu Lake
What is the water quality grade for Beaulieu Lake?
- Beaulieu Lake in Mahnomen County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.3 ft visibility. Phosphorus: 90 µg/L. Chlorophyll-a (algae): 55.8 µg/L. Surface area: 300 acres.
Is Beaulieu Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Beaulieu Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Algae concentration (chlorophyll-a) is 55.8 µg/L. Always check local health department advisories before swimming.
How deep is Beaulieu Lake?
- No published bathymetric survey covers Beaulieu Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 7 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 300 acres.
Explore Beaulieu Lake across LakeGrade
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Where this data comes from
4 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA4 samples · 2023
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2120 B ~ Color in Water by Visual Comparison
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder