Tumblesom
Tumblesom is a rockfill dam located in Boulder County, Colorado, built in 1918. It carries a Low hazard potential classification and has a fair condition assessment.
About Tumblesom
The primary purpose of Tumblesom 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 Denver Area Council Bsa (whitner, Dave) (private). It impounds the South St. Vrain Creek-tr near Lyons.
The dam stands 19 feet tall and stretches 186 feet across, creates a reservoir covering 16 acres, and has a maximum storage capacity of 149 acre-feet. Completed in 1918, the structure is over a century 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. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. The most recent inspection on record was 10/02/2020.
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Location
| State | Colorado |
| County | Boulder |
| Nearest City | Lyons |
| River/Stream | South St. Vrain Creek-tr |
| Coordinates | 40.10501, -105.49140 |
Physical Characteristics
| Dam Type | Rockfill |
| NID Height | 19 ft |
| Dam Height | 19 ft |
| Dam Length | 186 ft |
| Year Completed | 1918 (108 years old) |
Storage & Hydraulics
| NID Storage | 149 acre-ft |
| Max Storage | 149 acre-ft |
| Normal Storage | 85 acre-ft |
| Surface Area | 16 acres |
| Max Discharge | 96 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Fish and Wildlife Pond |
| Owner | DENVER AREA COUNCIL BSA (WHITNER, DAVE) |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 10/02/2020 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | CO00186 |
| Federal ID | CO00186 |
| More Info | State Dam Safety Program |