Mayfield, located in Lewis, Washington, is a public utility owned hydroelectric dam on the Cowlitz River. Built in 1963 by Harza Engineering Co., this arch-type dam stands at a height of 200 feet and has a structural height of 250 feet. With a storage capacity of 184,194 acre-feet and a normal storage of 133,718 acre-feet, Mayfield serves multiple purposes including hydroelectric power generation and recreation.

The dam's controlled spillway has a width of 205 feet, and it is equipped with five Tainter radial gates for water release. Mayfield's hazard potential is rated as high, with a very high risk assessment score of 1. Despite its age, the dam's condition assessment is currently not available. The Federal Energy Regulatory Commission oversees its regulatory and inspection activities, ensuring its safe operation and maintenance.

Mayfield's strategic location and significant storage capacity make it a vital water resource in the region. Its impressive hydraulic height of 230 feet contributes to its efficient power generation capabilities. With its rich history and crucial role in water management and energy production, Mayfield remains a fascinating site for water resource and climate enthusiasts to explore and learn from.