Brown Marsh Lake
Brown Marsh Lake in Lyon County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.6 ft visibility. Phosphorus: 98 µg/L. Chlorophyll-a (algae): 32.7 µg/L.
- Clarity
- 1.6 ft
- Mean depth
- ~8 ft est.
- Public access
- Yes
Next lake in Lyon County
Why Brown Marsh 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 Brown Marsh 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.
Brown Marsh Lake is a lake in Lyon County, Minnesota with an estimated average depth of about 8 feet. Limited fish-species data available. Public access is available with 3 public boat landings.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-08-28. 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 Brown Marsh Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 1.6 ft of visibility. Phosphorus level: 98 µg/L. Chlorophyll-a: 32.7 µg/L. Trophic State Index: 68.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | Not graded |
| Phosphorus | 98 µg/L | Not graded |
| Chlorophyll-a (Algae) | 32.7 µg/L | Not graded |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Brown Marsh Lake
Compare lakeside cabins, hotels, and vacation rentals near Brown Marsh Lake in Lyon 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.
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Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~8 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Brown Marsh 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.
Recreation & Access
- Brawner LakePublic
- RussellPublic
- Rock LakePublic
Fishing Brown Marsh Lake
Graded lakes near Brown Marsh Lake
Brown Marsh Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Lyon County
Frequently asked questions about Brown Marsh Lake
What is the water quality grade for Brown Marsh Lake?
- Brown Marsh Lake in Lyon County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.6 ft visibility. Phosphorus: 98 µg/L. Chlorophyll-a (algae): 32.7 µg/L.
Is Brown Marsh Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Brown Marsh Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Algae concentration (chlorophyll-a) is 32.7 µg/L. Always check local health department advisories before swimming.
How deep is Brown Marsh Lake?
- No published bathymetric survey covers Brown Marsh Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 8 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Brown Marsh Lake?
- Brown Marsh Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Brawner Lake, Russell, Rock Lake. Public access is listed as yes.
Explore Brown Marsh 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
Named boat-access points from the USGS National Boat Ramps inventory