Mossyrock Dam, completed in 1968, stands 606 feet from bedrock and is Washington’s tallest dam. It produces clean, renewable electricity that serves more than 78,000 Northwest homes  The dam has three penstocks between 248 and 285 feet in length that extend down to the powerhouse and is a double curvature concrete arch dam.

Mossyrock Dam forms Riffe Lake. Riffe (rhymes with "life") Lake, when it’s full, is 23 miles long, covers 11,830 acres and has 52 miles of shoreline. The lake was named after a small pioneering community that was covered when the lake was formed.