Allis
Allis is an earth dam located in Douglas County, Colorado, built in 1906. It carries a Low hazard potential classification and has a unsatisfactory condition assessment.
About Allis
The primary purpose of Allis is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Silver Spur Ranches (private). It impounds the Carpenter Creek-tr near Castle Rock.
The dam stands 45 feet tall and stretches 690 feet across, creates a reservoir covering 12 acres, has a maximum storage capacity of 225 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1906, 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 unsatisfactory, indicating serious safety deficiencies exist that require immediate attention or remedial action. The most recent inspection on record was 10/18/2022.
At 45 feet, this dam is taller than 91% of dams nationwide.
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Location
| State | Colorado |
| County | Douglas |
| Nearest City | Castle Rock |
| River/Stream | Carpenter Creek-tr |
| Coordinates | 39.13279, -104.85390 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 45 ft |
| Dam Height | 45 ft |
| Dam Length | 690 ft |
| Year Completed | 1906 (120 years old) |
Storage & Hydraulics
| NID Storage | 225 acre-ft |
| Max Storage | 225 acre-ft |
| Normal Storage | 140 acre-ft |
| Surface Area | 12 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 4,100 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | SILVER SPUR RANCHES |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Unsatisfactory |
| Last Inspection | 10/18/2022 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | CO01168 |
| Federal ID | CO01168 |
| More Info | State Dam Safety Program |