Mayfield Plunge Pool Barrier
Mayfield Plunge Pool Barrier is a dam located in Lewis County, Washington, built in 1963. It carries a Low hazard potential classification and has a satisfactory condition assessment.
About Mayfield Plunge Pool Barrier
The primary purpose of Mayfield Plunge Pool Barrier is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by City Of Tacoma (public utility). It impounds the Cowlitz River.
The dam stands 14 feet tall and stretches 200 feet across, creates a reservoir covering 2 acres, has a maximum storage capacity of 60 acre-feet, and collects water from a drainage area of 1,392 square miles. Completed in 1963, the structure is well into its service life at over 50 years old.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. 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 08/21/2025.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Washington |
| County | Lewis |
| Nearest City | None |
| River/Stream | Cowlitz River |
| Coordinates | 46.50270, -122.59150 |
Physical Characteristics
| NID Height | 14 ft |
| Dam Height | 14 ft |
| Dam Length | 200 ft |
| Year Completed | 1963 (63 years old) |
Storage & Hydraulics
| NID Storage | 60 acre-ft |
| Max Storage | 60 acre-ft |
| Normal Storage | 49 acre-ft |
| Surface Area | 2 acres |
| Drainage Area | 1,392 sq mi |
| Max Discharge | 313,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | City of Tacoma |
| Owner Type | Public Utility |
| Hazard Classification | Low |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/21/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WA00751 |
| Federal ID | WA00751 |
| More Info | State Dam Safety Program |