American Zinc Smelter Company Large Lake Dam is an earth dam located in Montgomery County, Illinois, built in 1916. It carries a Significant hazard potential classification.
Dam profile
NID height · 31 ft31 ft tall and 320 ft long, taller than 72% 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 American Zinc Smelter Company Large Lake Dam
The primary purpose of American Zinc Smelter Company Large Lake Dam is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Asarco Inc. (private). It impounds the Middle Fork Shoal Creek near Hillsboro.
The dam stands 31 feet tall and stretches 320 feet across, and has a maximum storage capacity of 300 acre-feet. Completed in 1916, the structure is over a century old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. The most recent inspection on record was 07/14/2021.
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Location
| State | Illinois |
| County | Montgomery |
| Nearest City | Hillsboro |
| River/Stream | Middle Fork Shoal Creek |
| Coordinates | 39.12976, -89.50501 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 31 ft |
| Dam Height | 31 ft |
| Dam Length | 320 ft |
| Year Completed | 1916 (110 years old) |
Storage & Hydraulics
| NID Storage | 300 acre-ft |
| Max Storage | 300 acre-ft |
| Normal Storage | 184 acre-ft |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Asarco Inc. |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 07/14/2021 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL01063 |
| Federal ID | IL01063 |
| More Info | State Dam Safety Program |