Chehalis River (Washington)
The Chehalis River (/ʃəˈheɪlɪs/ shə-HAY-lis) is a river in Washington in the United States. It originates in several forks in southwestern Washington, flows east, then north, then west, in a large curve, before emptying into Grays Harbor, an estuary of the Pacific Ocean. The river is the largest solely contained drainage basin in the state.
| Chehalis River | |
|---|---|
Chehalis River Valley (left), Grays Harbor (middle distance) and Satsop River Valley (along bottom) | |
Map of the Chehalis River watershed | |
Mouth of the Chehalis River in Washington Chehalis River (Washington) (the United States) | |
| Location | |
| Country | United States |
| State | Washington |
| Counties | Grays Harbor, Thurston, Lewis |
| Cities | Aberdeen, Centralia, Chehalis |
| Physical characteristics | |
| Source | |
| • location | Lewis County |
| • coordinates | 46°27′6″N 123°17′30″W |
| • elevation | 1,000 ft (300 m) |
| Mouth | Pacific Ocean |
• location | Grays Harbor, Aberdeen |
• coordinates | 46°57′29″N 123°50′5″W |
• elevation | 0 ft (0 m) |
| Length | 115 mi (185 km) |
| Basin size | 2,660 sq mi (6,900 km2) |
| Discharge | |
| • location | near Satsop, WA |
| • average | 6,425 cu ft/s (181.9 m3/s) |
| • minimum | 440 cu ft/s (12 m3/s) |
| • maximum | 47,000 cu ft/s (1,300 m3/s) |
| Discharge | |
| • location | mouth (Grays Harbor) |
| • average | 11,208 cu ft/s (317.4 m3/s) |
| Basin features | |
| Tributaries | |
| • right | South Fork Chehalis River, Newaukum River, Skookumchuck River, Satsop River, Wynoochee River, Wishkah River |
It was once much larger during the Ice Age when the tongue of the glacial ice sheet covering the Puget Sound terminated near Olympia and glacial runoff formed a large torrent of meltwater. This carved a large oversized valley that is much larger than the current river could have produced. The river's mouth was out near current Westport until rising sea levels at the end of the ice age flooded the broad Chehalis Valley to form a ria, known today as Grays Harbor.