Exxonmobil Coal Usa/mine 2/freshwater Lake Dam

Exxonmobil Coal Usa/mine 2/freshwater Lake Dam is a rockfill dam located in Clinton County, Illinois, built in 1975. It carries a Low hazard potential classification.

About Exxonmobil Coal Usa/mine 2/freshwater Lake Dam

The primary purpose of Exxonmobil Coal Usa/mine 2/freshwater Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Exxonmobil Environmental Services Compan (private). It impounds the Trib Grassy Branch near Damiansville.

The dam stands 15 feet tall and stretches 800 feet across, creates a reservoir covering 545 acres, has a maximum storage capacity of 423 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1975, the structure is well into its service life at over 50 years old.

This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. The most recent inspection on record was 07/24/2025.

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Low HazardNot Available ConditionEmergency Action Plan: No

Location

StateIllinois
CountyClinton
Nearest CityDamiansville
River/StreamTrib Grassy Branch
Coordinates38.53631, -89.60401

Physical Characteristics

Dam TypeRockfill
NID Height15 ft
Dam Height15 ft
Dam Length800 ft
Year Completed1975 (51 years old)

Storage & Hydraulics

NID Storage423 acre-ft
Max Storage423 acre-ft
Normal Storage187 acre-ft
Surface Area545 acres
Drainage Area1 sq mi
Max Discharge230 cfs
Spillway TypeUncontrolled

Ownership & Safety

PurposeRecreation
OwnerEXXONMOBIL ENVIRONMENTAL SERVICES COMPAN
Owner TypePrivate
Hazard ClassificationLow
Condition AssessmentNot Available
Last Inspection07/24/2025
Emergency Action PlanNo

Identifiers

NID IDIL50527
Federal IDIL50527
More InfoState Dam Safety Program

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