Otter Lake Low Flow Dam
Otter Lake Low Flow Dam is a rockfill dam located in Macoupin County, Illinois, built in 2008. It carries a Low hazard potential classification.
About Otter Lake Low Flow Dam
The primary purpose of Otter Lake Low Flow Dam is debris control. The dam is designed to catch sediment, rocks, and debris carried by flowing water — particularly important in areas prone to mudslides or heavy erosion. The dam is owned by Otter Lake Water Commission (public utility). It impounds the Otter Creek near Hagaman.
The dam stands 6 feet tall and stretches 317 feet across, creates a reservoir covering 42 acres, has a maximum storage capacity of 217 acre-feet, and collects water from a drainage area of 10 square miles. Completed in 2008, the structure is relatively new.
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 04/26/2023.
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Location
| State | Illinois |
| County | Macoupin |
| Nearest City | Hagaman |
| River/Stream | Otter Creek |
| Coordinates | 39.46276, -89.90087 |
Physical Characteristics
| Dam Type | Rockfill |
| NID Height | 6 ft |
| Dam Height | 6 ft |
| Dam Length | 317 ft |
| Year Completed | 2008 (18 years old) |
Storage & Hydraulics
| NID Storage | 217 acre-ft |
| Max Storage | 217 acre-ft |
| Normal Storage | 105 acre-ft |
| Surface Area | 42 acres |
| Drainage Area | 10 sq mi |
| Max Discharge | 2,087 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Debris Control |
| Owner | OTTER LAKE WATER COMMISSION |
| Owner Type | Public Utility |
| Hazard Classification | Low |
| Condition Assessment | Not Available |
| Last Inspection | 04/26/2023 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL50548 |
| Federal ID | IL50548 |
| More Info | State Dam Safety Program |