Foster is an earth dam located in Riverside County, California, built in 1945. It carries a High hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 38 ft38 ft tall and 277 ft long, taller than 84% of U.S. dams with a recorded height. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Foster
The primary purpose of Foster 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 Idyllwild Water District (public utility). It impounds the Lily Creek near Valle Vista.
The dam stands 38 feet tall and stretches 277 feet across, creates a reservoir covering 6 acres, has a maximum storage capacity of 56 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1945, the structure is well-established, with more than 75 years of service.
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. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 09/18/2025.
At 38 feet, this dam is taller than 84% of dams nationwide.
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 | Riverside |
| Nearest City | Valle Vista |
| River/Stream | Lily Creek |
| Coordinates | 33.75710, -116.72720 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 38 ft |
| Dam Height | 38 ft |
| Dam Length | 277 ft |
| Year Completed | 1945 (81 years old) |
Storage & Hydraulics
| NID Storage | 56 acre-ft |
| Max Storage | 56 acre-ft |
| Surface Area | 6 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Idyllwild Water District |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/18/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | CA00769 |
| Federal ID | CA00769 |
| More Info | State Dam Safety Program |