Marshall Lake
Marshall Lake is an earth dam located in Boulder County, Colorado, built in 1908. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Marshall Lake
The primary purpose of Marshall Lake is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Farmers Reservoir And Irrigation Company (edgar, S (private). It impounds the South Boulder Creek-tr near Marshall.
The dam stands 101 feet tall and stretches 2,370 feet across, creates a reservoir covering 305 acres, has a maximum storage capacity of 12,878 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1908, 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 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 06/03/2022.
At 101 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 | Boulder |
| Nearest City | Marshall |
| River/Stream | South Boulder Creek-tr |
| Coordinates | 39.95105, -105.20930 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 101 ft |
| Dam Height | 80 ft |
| Dam Length | 2,370 ft |
| Year Completed | 1908 (118 years old) |
Storage & Hydraulics
| NID Storage | 12,878 acre-ft |
| Max Storage | 12,878 acre-ft |
| Normal Storage | 11,545 acre-ft |
| Surface Area | 305 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 1,920 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | FARMERS RESERVOIR AND IRRIGATION COMPANY (EDGAR, S |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/03/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CO00241 |
| Federal ID | CO00241 |
| More Info | State Dam Safety Program |