Great Western
Great Western is an earth dam located in Broomfield County, Colorado, built in 1903. It carries a High hazard potential classification and has a fair condition assessment.
About Great Western
The primary purpose of Great Western 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 City Of Broomfield (middleton, Brennan) (local government). It impounds the Walnut Creek near Westminster.
The dam stands 83 feet tall and stretches 1,885 feet across, creates a reservoir covering 150 acres, has a maximum storage capacity of 4,459 acre-feet, and collects water from a drainage area of 4 square miles. Completed in 1903, the structure is over a century old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 05/03/2022.
At 83 feet, this dam is taller than 97% of all dams in the United States.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Colorado dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Colorado |
| County | Broomfield |
| Nearest City | Westminster |
| River/Stream | Walnut Creek |
| Coordinates | 39.89606, -105.14838 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 83 ft |
| Dam Height | 70 ft |
| Dam Length | 1,885 ft |
| Year Completed | 1903 (123 years old) |
Storage & Hydraulics
| NID Storage | 4,459 acre-ft |
| Max Storage | 4,459 acre-ft |
| Normal Storage | 2,200 acre-ft |
| Surface Area | 150 acres |
| Drainage Area | 4 sq mi |
| Max Discharge | 6,600 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | CITY OF BROOMFIELD (MIDDLETON, BRENNAN) |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 05/03/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CO00091 |
| Federal ID | CO00091 |
| More Info | State Dam Safety Program |