Where is Herrin Reservoir?

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

How deep is Herrin Reservoir?

Herrin Reservoir has a maximum depth of 13.5 feet and an average depth of 5 feet. The lake covers 50 acres.

Are there boat ramps on Herrin Reservoir?

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

Can I fish at Herrin Reservoir?

Herrin 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 Illinois's fish and wildlife agency, so check its current regulations before you go.

Herrin Reservoir

Williamson County, Illinois50 acresView map Directions

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

Max depth

13.5 ft

Bathymetric survey

Area

50 acres

Surface area

Shoreline

2 mi

Measured length

Impaired · Mercury
14 ft max depth
Public access

See the measurements Directions Where to stay

Herrin Reservoir in Williamson County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Maximum depth: 13.5 ft. Surface area: 50 acres.

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Herrin Reservoir is a 50-acre lake in Williamson County, Illinois with a maximum depth of 14 feet (5-foot average). Limited fish-species data available. Public access is available with 1 public boat landing.

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

What Herrin Reservoir is good for

From access and monitoring records, not editorial picks.

Boat launch1 documented ramp

Swimming conditions

No reading

Not rated

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

Whether Herrin Reservoir 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 Herrin Reservoir

These are the measurements Illinois EPA publishes for Herrin 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 Herrin Reservoir

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

Lake Details

Max depth

13.5 ft

Average depth

5 ft

Surface area

50 acres

Shoreline

2 mi

Public access

Yes

Listed by Illinois EPA

Recreation & Access

Boat Landings

Yes

Public Access

Herrin Lake #1Public

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

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Stays near Herrin Reservoir

Compare lakeside cabins, hotels, and vacation rentals near Herrin Reservoir 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 Herrin Reservoir

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Fishing Herrin Reservoir

→ Herrin Reservoir fishing regulations (limits, seasons, special rules)

EPA Impairment Status

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

Causes of impairment

MercuryNutrients (phosphorus, nitrogen)PCBsTurbidity

Designated uses not supporting: Fish consumption, Other.

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

Source: EPA ATTAINS assessment unit IL_RNZD · Official waterbody report

Nearby Lakes in Williamson County

Crab Orchard Lake4.6 miView →Madison Lake5.3 miView →Marion Reservoir7.2 miView →Teal Lake8.4 miView →Herrin Lake9.2 miView →Sweet Lake8.3 miView →

Frequently asked questions about Herrin Reservoir

Where is Herrin Reservoir?: Herrin Reservoir 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 Herrin Reservoir?: Herrin Reservoir in Williamson County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Maximum depth: 13.5 ft. Surface area: 50 acres.
Is Herrin Reservoir safe to swim in?: Nutrient and algae readings are not a swimming clearance. Herrin Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), pCBs, turbidity. Check local advisories before you swim.
How deep is Herrin Reservoir?: Herrin Reservoir has a maximum depth of 13.5 feet and an average depth of 5 feet. The lake covers 50 acres.
Are there boat ramps on Herrin Reservoir?: Herrin Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Herrin Lake #1. Public access is listed as yes.
Can I fish at Herrin Reservoir?: Herrin 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 Illinois's fish and wildlife agency, so check its current regulations before you go.