Harper Lake
Harper Lake is an earth dam located in Boulder County, Colorado, built in 1985. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Harper Lake
The primary purpose of Harper 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 City Of Louisville (kowar, Kurt) (local government). It impounds the Coal Creek-tr near Louisville.
The dam stands 11 feet tall and stretches 2,200 feet across, creates a reservoir covering 31 acres, and has a maximum storage capacity of 843 acre-feet. Completed in 1985, the structure is 41 years 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 satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 10/11/2022.
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 | Boulder |
| Nearest City | Louisville |
| River/Stream | Coal Creek-tr |
| Coordinates | 39.98141, -105.16100 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 11 ft |
| Dam Height | 11 ft |
| Dam Length | 2,200 ft |
| Year Completed | 1985 (41 years old) |
Storage & Hydraulics
| NID Storage | 843 acre-ft |
| Max Storage | 843 acre-ft |
| Normal Storage | 715 acre-ft |
| Surface Area | 31 acres |
| Max Discharge | 460 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | CITY OF LOUISVILLE (KOWAR, KURT) |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 10/11/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CO02674 |
| Federal ID | CO02674 |
| More Info | State Dam Safety Program |