Upper Highline
Upper Highline is an earth dam located in Mesa County, Colorado, built in 1967. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Upper Highline
The primary purpose of Upper Highline is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Colorado Parks And Wildlife (taylor, Margaret) (state). It impounds the Mack Wash-tr near Mack.
The dam stands 98 feet tall and stretches 1,440 feet across, creates a reservoir covering 155 acres, has a maximum storage capacity of 7,125 acre-feet, and collects water from a drainage area of 13 square miles. Completed in 1967, the structure is well into its service life at over 50 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 09/07/2022.
At 98 feet, this dam is taller than 98% 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 | Mesa |
| Nearest City | Mack |
| River/Stream | Mack Wash-tr |
| Coordinates | 39.27001, -108.84557 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 98 ft |
| Dam Height | 87 ft |
| Dam Length | 1,440 ft |
| Year Completed | 1967 (59 years old) |
Storage & Hydraulics
| NID Storage | 7,125 acre-ft |
| Max Storage | 7,125 acre-ft |
| Normal Storage | 3,400 acre-ft |
| Surface Area | 155 acres |
| Drainage Area | 13 sq mi |
| Max Discharge | 2,600 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | COLORADO PARKS AND WILDLIFE (TAYLOR, MARGARET) |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/07/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CO00831 |
| Federal ID | CO00831 |
| More Info | State Dam Safety Program |