Where is Boulder Lake Reservoir?

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

Are there boat ramps on Boulder Lake Reservoir?

Boulder Lake Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Boulder Lake. Public access is listed as yes.

Can I fish at Boulder Lake Reservoir?

Boulder Lake Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. 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.

Boulder Lake Reservoir

St. Louis County, Minnesota3,287 acresView map Directions

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

Area

3,287 acres

Surface area

Shoreline

32.9 mi

Measured length

Impaired · Mercury
Public access

See the measurements Directions Where to stay

Boulder Lake Reservoir in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Surface area: 3287 acres.

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Boulder Lake Reservoir is a 3,287-acre lake in St. Louis County, Minnesota. Limited fish-species data available. Public access is available with 1 public boat landing.

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

What Boulder Lake Reservoir is good for

From access and monitoring records, not editorial picks.

Boat launch1 documented ramp
Big water3,287 acres

Swimming conditions

No reading

Not rated

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

Whether Boulder Lake Reservoir 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 Boulder Lake Reservoir

These are the measurements Minnesota PCA publishes for Boulder Lake Reservoir, 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 Boulder Lake Reservoir

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

Lake Details

Surface area

3,287 acres

Shoreline

32.9 mi

Public access

Yes

Listed by Minnesota PCA

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

Recreation & Access

Boat Landings

Yes

Public Access

Boulder LakePublic

Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps

Stays via Stay22

Stays near Boulder Lake Reservoir

Compare lakeside cabins, hotels, and vacation rentals near Boulder Lake Reservoir 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 Boulder Lake Reservoir

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Follow Boulder Lake Reservoir’s readings

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Fishing Boulder Lake Reservoir

→ Boulder Lake Reservoir fishing regulations (limits, seasons, special rules)

EPA Impairment Status

Boulder Lake Reservoir 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 MN69-0373-00 · Official waterbody report

Nearby Lakes in St. Louis County

Twin Lakes2.6 miView →Twin Lakes3 miView →Island Lake Reservoir3.7 miView →Apple Lake4.1 miView →Nevens Lake3.8 miView →Flowage Lake8.5 ft clear—View →

Frequently asked questions about Boulder Lake Reservoir

Where is Boulder Lake Reservoir?: Boulder Lake Reservoir 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 Boulder Lake Reservoir?: Boulder Lake Reservoir in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Surface area: 3287 acres.
Is Boulder Lake Reservoir safe to swim in?: Nutrient and algae readings are not a swimming clearance. Boulder Lake Reservoir is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Are there boat ramps on Boulder Lake Reservoir?: Boulder Lake Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Boulder Lake. Public access is listed as yes.
Can I fish at Boulder Lake Reservoir?: Boulder Lake Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. 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.