Maximum discharge along the river is currently at the reporting a streamflow rate of cfs. This is also the highest stage along the Greenwater River, with a gauge stage of ft at this location. This river is monitored from 1 different streamgauging stations along the Greenwater River, the highest being situated at an altitude of ft, the .

The Greenwater River is a river located in western Washington state, USA. It stretches for 38 miles from its source on the western slopes of the Cascade Mountains to its confluence with the White River. The river is known for its clear green water from the glacial melt of Mount Rainier.

The river has a long history of providing water for irrigation and hydroelectric power generation. The White River Hydroelectric Project was constructed in the early 1900s, creating a series of reservoirs and dams along the Greenwater River. The largest reservoir, Howard Hanson Dam, is used for flood control, recreation, and fish habitat. Other smaller reservoirs, such as Mud Mountain Dam and Auburn Dam, provide irrigation water for farmland in the surrounding valley.

Recreational activities on the river include fishing, kayaking, and whitewater rafting. The river is also home to a variety of fish species, including chinook salmon and steelhead trout. The Greenwater River and its surrounding landscape are protected and managed by the National Park Service as part of the Mount Rainier National Park.