The Greenwater River is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 in the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Washington. Its watershed

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 drains a portion of the Cascade Range

Cascade Range

The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

 east and northeast of Mount Rainier

Mount Rainier

Mount Rainier is a massive stratovolcano located southeast of Seattle in the state of Washington, United States. It is the most topographically prominent mountain in the contiguous United States and the Cascade Volcanic Arc, with a summit elevation of . Mt. Rainier is considered one of the most...

, including parts of the Norse Peak Wilderness

Norse Peak Wilderness

Norse Peak Wilderness is located in central Washington in the United States. It protects the portion of the Cascade Range north of Chinook Pass , south of Naches Pass , and east of Mt. Rainier National Park. This 50,923 acre wilderness is named for a prominent peak which overlooks Crystal Mountain...

. It flows into the White River

White River (Washington)

The White River is a white, glacial river in the U.S. state of Washington. It flows about 75 miles from its source, the Emmons Glacier on Mount Rainier, to join the Puyallup River at Sumner...

 at Greenwater

Greenwater, Washington

Greenwater is a census-designated place in Pierce County, Washington, United States. The population was 67 at the 2010 census.Based on per capita income, Greenwater ranks 17th of 522 areas in the state of Washington to be ranked...

, which eventually flows into Puget Sound

Puget Sound

Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...

 via the Puyallup River

Puyallup River

The Puyallup River is a river in the U.S. state of Washington. About long, it is formed by glaciers on the west side of Mount Rainier. It flows generally northwest, emptying into Commencement Bay, part of Puget Sound...

. The Greenwater River defines part of the boundary between King

King County, Washington

King County is a county located in the U.S. state of Washington. The population in the 2010 census was 1,931,249. King is the most populous county in Washington, and the 14th most populous in the United States....

 and Pierce

Pierce County, Washington

right|thumb|[[Tacoma, Washington|Tacoma]] - Seat of Pierce CountyPierce County is the second most populous county in the U.S. state of Washington. Formed out of Thurston County on December 22, 1852, by the legislature of Oregon Territory...

 counties.

Course

The Greenwater River rises in eastern Pierce County, in the Norse Peaks Wilderness near Corral Pass. Along with a few headwater tributaries, it drains the north side of Castle Mountain. The Greenwater flows north, through Hidden Lake and then Echo Lake. After Echo Lake the river bends slightly westward, collects the tributary streams Maggie Creek, Lost Creek, and Meadow Creek, then turning more fully west.

Meadow Creek rises near Naches Pass

Naches Pass

Naches Pass is a mountain pass of the Cascade Range in the U.S. state of Washington. It is located about east of Tacoma and about northwest of Yakima, near the headwaters of tributary streams of the Naches River on the east and the Greenwater River on the west. The boundaries of Pierce, King,...

, flowing through Government Meadows before joining the Greenwater River. The boundary between King and Pierce counties follows Meadow Creek down from Naches Pass. Then the boundary follows the Greenwater for the rest of its course to the White River.

Below Meadow Creek, the Greenwater River passes through two small ponds called Greenwater Lakes. It collects a number of tributary streams as it flows west, including George Creek, which flows from George Lake near Noble Knob, and Pyramid Creek, which flows from its source at Pyramid Peak.

As the Greenwater River approaches the White River, it is flanked by Huckleberry Mountain to the north and Dalles Ridge to the south. The Greenwater River joins the White River at the small community of Greenwater.