Koster Pond Dam is an earth dam located in Greene County, Illinois, built in 1963. It carries a Low hazard potential classification.
Dam profile
NID height · 27 ft27 ft tall and 134 ft long, taller than 59% of U.S. dams with a recorded height. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Koster Pond Dam
The primary purpose of Koster Pond Dam is fish and wildlife pond. The dam creates habitat for fish and wildlife, supporting local ecosystems and potentially serving conservation goals. The dam is owned by John C. Koster;john C. Koster (private). It impounds the Sand Creek near Spanky.
The dam stands 27 feet tall and stretches 134 feet across, creates a reservoir covering 2 acres, has a maximum storage capacity of 25 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1963, 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 08/27/2025.
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Location
| State | Illinois |
| County | Greene |
| Nearest City | Spanky |
| River/Stream | Sand Creek |
| Coordinates | 39.27833, -90.36302 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 27 ft |
| Dam Height | 27 ft |
| Dam Length | 134 ft |
| Year Completed | 1963 (63 years old) |
Storage & Hydraulics
| NID Storage | 25 acre-ft |
| Max Storage | 25 acre-ft |
| Normal Storage | 18 acre-ft |
| Surface Area | 2 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 150 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Fish and Wildlife Pond |
| Owner | John C. Koster;john C. Koster |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Last Inspection | 08/27/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL40024 |
| Federal ID | IL40024 |
| More Info | State Dam Safety Program |