Where is Half Moon Lake?

Half Moon Lake is a lake in St. Louis County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.

Half Moon Lake

St. Louis County, Minnesota159 acresView map Directions

No nutrient or algae sampling on record from Minnesota PCA for this lake.

Area

159 acres

Surface area

Shoreline

3.6 mi

Measured length

Impaired · Mercury

See the measurements Directions Where to stay

Half Moon Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Surface area: 159 acres.

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Half Moon Lake is a 159-acre lake in St. Louis County, Minnesota.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder. Methodology: how these readings are compared.

Swimming conditions

No reading

Not rated

Nutrient and algae readings are not a swimming clearance. Half Moon Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.

Whether Half Moon 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 Half Moon Lake

These are the measurements Minnesota PCA publishes for Half Moon Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.

No clarity data. TSI undefined.

Ask about Half Moon Lake

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

Lake Details

Surface area

159 acres

Shoreline

3.6 mi

No bathymetric survey has been published for Half Moon Lake, so its depth is not documented here.

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Stays near Half Moon Lake

Compare lakeside cabins, hotels, and vacation rentals near Half Moon Lake in St. Louis 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.

Top-rated places to stay near Half Moon Lake

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Fishing Half Moon Lake

→ Half Moon Lake fishing regulations (limits, seasons, special rules)

EPA Impairment Status

Half Moon Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Mercury

Designated uses not supporting: Fish consumption.

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit MN69-0657-00 · Official waterbody report

Nearby Lakes in St. Louis County

Moon Lake0.7 miView →Horseshoe Lake2.1 miView →Pleasant Lake10 ft clear · Mesotrophic1.8 miView →Long Lake12.5 ft clear2 miView →St. Marys Lake13.1 ft clear · Oligotrophic3.3 miView →St Mary'S Lake15 ft clear3.5 miView →

Frequently asked questions about Half Moon Lake

Where is Half Moon Lake?: Half Moon Lake is a lake in St. Louis County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Half Moon Lake?: Half Moon Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Surface area: 159 acres.
Is Half Moon Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Half Moon Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.