The reservoir known as Riffe Lake is 23.5 miles (38 km) along the Cowlitz River in Washington. It was created in 1968 after Mossyrock Dam’s completion. The lake is the result of efforts by Tacoma City Light (now Tacoma Power) and is the tallest dam in the state.
The formation of the reservoir in the late 1960s submerged the communities of Kosmos, Nesika, and Riffe, leading to the relocation of residents. Initially named Mossyrock Lake and later Davisson Lake after Tacoma Utilities Commissioner Ira Davisson, it was officially renamed Riffe Lake in 1976. This change honored the submerged community following petitions by residents.
In 2017, Tacoma Power lowered the lake’s maximum water level by 30 feet (9.1 m) due to seismic concerns about Mossyrock Dam’s piers, potentially preventing catastrophic flooding.
Riffe Lake features two parks: Mossyrock Park and Taidnapam Park. Due to fluctuating water levels, boat launches at both parks have faced periodic closures since 2017, with ongoing efforts to extend the launches for consistent accessibility. Numerous fish species may be found in the lake, such as landlocked coho, rainbow and brown trout, largemouth and smallmouth bass, bluegill, crappie, and perch.