Olson Lake is a lake in Big Stone County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.

How deep is Olson Lake?

No published bathymetric survey covers Olson Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 24 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.

Can I fish at Olson Lake?

Public access to Olson 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.

Olson Lake

Big Stone County, MinnesotaView map Directions

Minnesota PCA publishes the water-quality measurements for Olson Lake. Here is what has been measured.

Clarity

0.7 ft

Murkier than most

Secchi · sampled 2023

Phosphorus

774 µg/L

More phosphorus than most

Measured by Minnesota PCA

Chlorophyll-a

384 µg/L

More algae than most

Measured by Minnesota PCA

Max depth

~24 ft est.

GLOBathy model

24 ft max depth
Limited data

See the measurements Directions Where to stay

Olson Lake in Big Stone County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 0.7 ft visibility. Phosphorus: 774 µg/L. Chlorophyll-a (algae): 384 µg/L.

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Olson Lake is a lake in Big Stone County, Minnesota with an estimated average depth of about 24 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 2023-07-31. Methodology: how these readings are compared.

Swimming conditions

No reading

Limited data

Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.

Whether Olson 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.

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Water quality measurements for Olson Lake

These are the measurements Minnesota PCA publishes for Olson 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 0.7 ft of visibility. Phosphorus 774 µg/L. Chlorophyll-a 384 µg/L. TSI 91.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)	0.7ft	Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer.
Total phosphorus	774µg/L	Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential.
Chlorophyll-a (algae)	384µg/L	Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water.
Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a.	91	Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic

Very high nutrients, dense algae, poor clarity

Ask about Olson Lake

Answers come straight from the public measurements and survey records on this page.

Lake Details

Max depth

~24 ft est.

Public access

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 Olson Lake.

Lake Size & Watershed

Watershed (drainage) area

3 sq mi

HydroLAKES / HydroSHEDS

Surface area

126 acres

HydroLAKES / HydroSHEDS

Shoreline

2.6 mi

HydroLAKES / HydroSHEDS

Elevation

1,096 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.

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Stays near Olson Lake

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Fishing Olson Lake

→ Olson Lake fishing regulations (limits, seasons, special rules)

Nearby Lakes in Big Stone County

Bentsen Lake—View →Munnwyler Lake—View →Otrey Lake1 ft clear—View →Thielke Lake—View →Larson Lake—View →Bassett Slough—View →

Frequently asked questions about Olson Lake

Where is Olson Lake?: Olson Lake is a lake in Big Stone County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Olson Lake?: Olson Lake in Big Stone County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 0.7 ft visibility. Phosphorus: 774 µg/L. Chlorophyll-a (algae): 384 µg/L.
Is Olson Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Olson Lake?: No published bathymetric survey covers Olson Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 24 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Can I fish at Olson Lake?: Public access to Olson 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.

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State Parks Near Olson Lake

Big Stone Lake State Park

State Park · 8.7 mi

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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 WaterMNPCA4 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)

MNPCA-06-0069-00-201

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.