Phoenix Lake
Phoenix Lake is an earth dam located in Marin County, California, built in 1907. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Phoenix Lake
The primary purpose of Phoenix 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 Marin Municipal Water District (public utility). It impounds the Ross Creek near Ross.
The dam stands 90 feet tall and stretches 320 feet across, creates a reservoir covering 17 acres, has a maximum storage capacity of 420 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1907, 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 09/18/2025.
At 90 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 California 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 | California |
| County | Marin |
| Nearest City | Ross |
| River/Stream | Ross Creek |
| Coordinates | 37.95530, -122.57520 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 90 ft |
| Dam Height | 90 ft |
| Dam Length | 320 ft |
| Year Completed | 1907 (119 years old) |
Storage & Hydraulics
| NID Storage | 420 acre-ft |
| Max Storage | 420 acre-ft |
| Surface Area | 17 acres |
| Drainage Area | 2 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Marin Municipal Water District |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/18/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00206 |
| Federal ID | CA00206 |
| More Info | State Dam Safety Program |