Johnston City Lake
Williamson County, Illinois60 acresView mapDirections
No nutrient or algae sampling on record from Illinois EPA for this lake.
- Impaired · Algal growth
- 13 ft max depth
Johnston City Lake in Williamson County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Maximum depth: 13 ft. Surface area: 60 acres.
Johnston City Lake is a 60-acre lake in Williamson County, Illinois with a maximum depth of 13 feet (6-foot average).
Source: EPA Water Quality Portal sampling records, Illinois EPA. Methodology: how these readings are compared.
Swimming conditions
No readingNot rated
Nutrient and algae readings are not a swimming clearance. Johnston City Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen), turbidity. Check local advisories before you swim.
Whether Johnston City 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.
Water quality measurements for Johnston City Lake
These are the measurements Illinois EPA publishes for Johnston City 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 Johnston City Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
13 ft
Average depth
6 ft
Surface area
60 acres
Shoreline
1.9 mi
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Fishing Johnston City Lake
EPA Impairment Status
Johnston City Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Other.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_RNZE · Official waterbody report
Nearby Lakes in Williamson County
Frequently asked questions about Johnston City Lake
Where is Johnston City Lake?
- Johnston City 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 Johnston City Lake?
- Johnston City Lake in Williamson County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Maximum depth: 13 ft. Surface area: 60 acres.
Is Johnston City Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Johnston City Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen), turbidity. Check local advisories before you swim.
How deep is Johnston City Lake?
- Johnston City Lake has a maximum depth of 13 feet and an average depth of 6 feet. The lake covers 60 acres.
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Where this data comes from
Measurements for Johnston City Lake come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database