Sweet Lake is a lake in Williamson County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.

Sweet Lake

Williamson County, Illinois37 acresView map Directions

No nutrient or algae sampling on record from Illinois EPA for this lake.

Area

37 acres

Surface area

Shoreline

1.9 mi

Measured length

Impaired · Nutrients (phosphorus, nitrogen)

See the measurements Directions Where to stay

Sweet Lake in Williamson County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Surface area: 37 acres.

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Sweet Lake is a 37-acre lake in Williamson County, Illinois.

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

Swimming conditions

No reading

Not rated

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

Whether Sweet Lake is safe to swim in today is a call for the Illinois Environmental Protection Agency and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.

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Water quality measurements for Sweet Lake

These are the measurements Illinois EPA publishes for Sweet 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 Sweet Lake

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

Lake Details

Surface area

37 acres

Shoreline

1.9 mi

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

Stays via Stay22

Stays near Sweet Lake

Compare lakeside cabins, hotels, and vacation rentals near Sweet Lake in Williamson County, Illinois — 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 Sweet Lake

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Fishing Sweet Lake

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

EPA Impairment Status

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

Causes of impairment

Nutrients (phosphorus, nitrogen)

Designated uses not supporting: Other.

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

Source: EPA ATTAINS assessment unit IL_RNZX · Official waterbody report

Nearby Lakes in Williamson County

Fresh Water Lake2.6 miView →Johnston City Lake3.1 miView →Herrin Reservoir8.3 miView →Marion Reservoir—View →Teal Lake—View →Marion Country Club Lake—View →

Frequently asked questions about Sweet Lake

Where is Sweet Lake?: Sweet Lake is a lake in Williamson County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Sweet Lake?: Sweet Lake in Williamson County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Surface area: 37 acres.
Is Sweet Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Sweet Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.