Silver Falls on the Ohanapecosh River in Mount Rainier National Park
|- location||Cascade Range|
|- elevation||6,050 ft (1,840 m)|
|1,230 ft (370 m)|
|Length||16 mi (26 km)|
|Basin size||68.5 sq mi (177 km2)|
|- location||USGS gage 14224000 near Lewis, WA (historical: 1908-1912)|
|- average||572.92 cu ft/s (16.223 m3/s)|
|- minimum||58 cu ft/s (1.6 m3/s)|
|- maximum||7,500 cu ft/s (210 m3/s)|
It is the main headwater tributary of the Cowlitz River, which begins at the confluence of the Ohanapecosh River and the Clear Fork Cowlitz River. The Ohanapecosh originates near Ohanapecosh Glacier on the southeast side of Mount Rainier. Most of the river is within Mount Rainier National Park. Its final reach is in Gifford Pinchot National Forest.
Mount Rainier is the source of nine major rivers and their tributaries: the Nisqually, Puyallup, Mowich, Carbon, West Fork White, Huckleberry, White, Ohanapecosh, and Muddy Fork rivers. Of these only the Ohanapecosh and Huckleberry are non-glacial. All of these rivers empty into Puget Sound near Tacoma, Washington, except the Muddy Fork and Ohanapecosh, which flow into the Cowlitz River, a tributary of the Columbia River.
The Ohanapecosh River is named for a Taidnapam (Upper Cowlitz) Indian habitation site along the river, /áw-xanapaykaš/, meaning "standing at the edge". The Washington Place Names database says the name means "clear stream...deep blue...or deep blue holes". The database also relates a story from the June 6, 1953 Centralia Chronicle which claimed the name "may also be a corruption of the English words Oh, my gosh."
The Ohanapecosh River originates from meltwaters of the lower part of Ohanapecosh Glacier on the southeastern slopes of Mount Rainier. It flows southeast through Indian Bar, a broad, flat area of rocky debris. At approximately Ohanapecosh river mile 15 the Ohanapecosh plunges over Wauhaukaupauken Falls. The Wonderland Trail crosses the river near the falls. North of the river there is an alpine cirque known as Ohanapecosh Park. A similar cirque to the south is called Cowlitz Park. Below Wauhaukaupauken Falls the Ohanapecosh then flows more generally east over more waterfalls. The tributary Boulder Creek joins from the north.
Below Boulder Creek the Ohanapecosh flows southeast. At approximately river mile 10.5 the Eastside Trail crosses the river near a waterfall. Then the river is joined by Chinook Creek from the north. The Ohanapecosh turns south and flows through a broad glacial U-shaped valley, which it shares with Washington State Route 123, east of the river, and the Eastside Trail on the west side of the river. Many tributary streams joins the river, including Panther Creek from the east and Olallie Creek from the west. Shortly below Panther Creek the Ohanapecosh exits Pierce County and enters Lewis County. Below Olallie Creek the Ohanapecosh River flows through a broad flat bottomland called Cedar Flats. The river splits into two channels which join at the south end of Cedar Flats. The Grove of the Patriarchs trail crosses the river and loops through the island created by the Ohanapecosh's channels.
Just downstream from the rejoining of the two channels the Ohanapecosh flows by the east end of Stevens Canyon Road, which joins State Route 123 near the river. The high ridge west of the Ohanapecosh River north of the Stevens Canyon entrance road is called the Cowlitz Divide. South of the Stevens Canyon entrance the ridge is called Backbone Ridge. Both form a continuous ridgeline separating the watershed of the Ohanapecosh from the Muddy Fork Cowlitz River.
The river plunges over Silver Falls near river mile 6, between Stevens Canyon Road and Laughingwater Creek.
Just below that the river is joined by Laughingwater Creek from the east. At approximately river mile 5, less than a mile below Laughingwater Creek, the Ohanapecosh flows by Ohanapecosh Hot Springs and the Ohanapecosh Campground, Visitor Center, and Ranger Station. This southeastern part of Mount Rainier National Park is known as the Ohanapecosh area. After flowing through it the river exits the national park and enters Gifford Pinchot National Forest.
Continuing south the Ohanapecosh is joined by Carlton Creek and Summit Creek from the east. Near La Wis Wis Campground the Ohanapecosh River joins the Clear Fork Cowlitz River. Below the confluence the stream is called the Cowlitz River. State Route 123 ends near La Wis Wis, joining U.S. Route 12. Route 12 continues to follow the Cowlitz River downstream.
- U.S. Geological Survey Geographic Names Information System: Ohanapecosh River
- Derived from Google Earth search using Geographic Names Information System (GNIS) source coordinates.
- "National Hydrography Dataset". United States Geological Survey. Retrieved 14 June 2011.
- "USGS gage 14224000 Ohanapecosh River near Lewis, WA". United States Geological Survey. Retrieved 4 September 2009.
- Bright, William (2004). Native American placenames of the United States. University of Oklahoma Press. p. 344. ISBN 978-0-8061-3598-4. Retrieved 11 July 2011.
- General course and elevation info from USGS topographic maps accessed via the "GNIS in Google Map" feature of the USGS Geographic Names Information System website
- "Water Quality, Mount Rainier National Park". National Park Service. Retrieved 4 September 2009.
- "Ohanapecosh". National Park Service. Retrieved 4 September 2009.
- "Ohanapecosh". Washington Place Names database. Tacoma Public Library. Archived from the original on March 9, 2009. Retrieved 4 September 2009.
- Washington Road & Recreation Atlas (Fourth ed.). Benchmark Maps. 2007. ISBN 978-0-929591-98-8.
- Green Trails Map No. 270, Mount Rainier East, WA. http://www.greentrailsmaps.com
- U.S. Geological Survey Geographic Names Information System: Ohanapecosh Glacier
- U.S. Geological Survey Geographic Names Information System: Ohanapecosh Park
- U.S. Geological Survey Geographic Names Information System: Ohanapecosh Hot Springs
- U.S. Geological Survey Geographic Names Information System: Ohanapecosh Campground
- U.S. Geological Survey Geographic Names Information System: Ohanapecosh Visitor Center
- U.S. Geological Survey Geographic Names Information System: Ohanapecosh