Lost Lake is a lake in Marathon County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.

How deep is Lost Lake?

Lost Lake has a maximum depth of 23 feet. The lake covers 42 acres.

Are there boat ramps on Lost Lake?

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

Can I fish at Lost Lake?

Lost Lake 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 Wisconsin's fish and wildlife agency, so check its current regulations before you go.

Lost Lake

Marathon County, Wisconsin42 acresView map Directions

No nutrient or algae sampling on record from Wisconsin DNR for this lake.

Max depth

23 ft

Bathymetric survey

Area

42 acres

Surface area

Shoreline

1 mi

Measured length

Impaired · Nutrients (phosphorus, nitrogen)
23 ft max depth
Public access

See the measurements Directions Where to stay

Lost Lake in Marathon County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Maximum depth: 23 ft. Surface area: 42 acres.

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Lost Lake is a 42-acre lake in Marathon County, Wisconsin with a maximum depth of 23 feet. Limited fish-species data available. Public access is available with 1 public boat landing.

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

What Lost Lake is good for

From access and monitoring records, not editorial picks.

Boat launch1 documented ramp

Swimming conditions

No reading

Recreation use not supported

Nutrient and algae readings are not a swimming clearance. Lost Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.

Whether Lost Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.

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Water quality measurements for Lost Lake

These are the measurements Wisconsin DNR publishes for Lost 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 Lost Lake

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

Lake Details

Max depth

23 ft

Surface area

42 acres

Shoreline

1 mi

Public access

Yes

Listed by Wisconsin DNR

Recreation & Access

Boat Landings

Yes

Public Access

Lost 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 Lost Lake

Compare lakeside cabins, hotels, and vacation rentals near Lost Lake in Marathon County, Wisconsin — 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 Lost Lake

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Follow Lost Lake’s readings

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Fishing Lost Lake

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

EPA Impairment Status

Lost Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Nutrients (phosphorus, nitrogen)

Designated uses not supporting: Aquatic life, Recreation.

Source: EPA ATTAINS assessment unit WI10008658 · Official waterbody report

Nearby Lakes in Marathon County

Rice Lake1.3 miView →Bass Lake1.3 miView →Pike Lake5 ft clear · Eutrophic2.4 miView →Mission Lake5 miView →Norrie Lake4.5 miView →Mud Lake5.4 miView →

Frequently asked questions about Lost Lake

Where is Lost Lake?: Lost Lake is a lake in Marathon County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Lost Lake?: Lost Lake in Marathon County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Maximum depth: 23 ft. Surface area: 42 acres.
Is Lost Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Lost Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Lost Lake?: Lost Lake has a maximum depth of 23 feet. The lake covers 42 acres.
Are there boat ramps on Lost Lake?: Lost Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lost Lake. Public access is listed as yes.
Can I fish at Lost Lake?: Lost Lake 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 Wisconsin's fish and wildlife agency, so check its current regulations before you go.