St. Marys Lake
St. Marys Lake is an earth dam located in Clear Creek County, Colorado, built in 1889. It carries a Significant hazard potential classification.
About St. Marys Lake
The primary purpose of St. Marys Lake 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 Coors Brewing Co. Land & Water Resources (santange (private). It impounds the Silver Creek-os near Idaho Springs.
The dam stands 9 feet tall and stretches 210 feet across, creates a reservoir covering 7 acres, and has a maximum storage capacity of 51 acre-feet. Completed in 1889, 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. An emergency action plan is in place for this dam. The most recent inspection on record was 09/28/2022.
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Location
| State | Colorado |
| County | Clear Creek |
| Nearest City | Idaho Springs |
| River/Stream | Silver Creek-os |
| Coordinates | 39.83263, -105.64544 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 9 ft |
| Dam Height | 9 ft |
| Dam Length | 210 ft |
| Year Completed | 1889 (137 years old) |
Storage & Hydraulics
| NID Storage | 51 acre-ft |
| Max Storage | 51 acre-ft |
| Normal Storage | 38 acre-ft |
| Surface Area | 7 acres |
| Max Discharge | 220 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | COORS BREWING CO. LAND & WATER RESOURCES (SANTANGE |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not Rated |
| Last Inspection | 09/28/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CO01188 |
| Federal ID | CO01188 |
| More Info | State Dam Safety Program |