Overview of the Chehalis River Basin

The Chehalis River Basin lies between the Deschutes River Basin on the east and the Cowlitz River Basin on the south, the Willapa Hills on the west, and the Olympic Range on the north as shown on this overview map.. The basin includes parts of Lewis, Thurston, Cowlitz, Pacific, Grays Harbor, Mason, Jefferson and Wahkiakum counties.

The Chehalis River Basin is the second largest river basin in the state of Washington outside the Columbia River Basin. The total drainage area of the Chehalis River Basin is 2,660 square miles of which approximately 85% is forest lands. Approximately 257 square miles (164,000 acres), or 9.7% of the basin is agricultural land.

The Chehalis River system is largely rain-fed with precipitation levels which range from 45 inches per year in the eastern Chehalis River valley to over 200 inches in the Olympic Mountains. Estimated average annual discharge of the entire basin is 11,208 cubic feet per second (cfs).

The four major population centers, Chehalis, Centralia, Aberdeen, and Hoquiam, depend on surface waters of the basin for the largest portion of their municipal and industrial supplies. The principal industrial use of water is in the manufacturing of wood, pulp and paper products. Aberdeen's industrial water system supplies most of this water from the Wynoochee River, with the remainder from Lake Aberdeen.

Land within the basin is mostly forest cover with interspersed agricultural and residential areas. Forest lands, which constitute approximately 77% of the Upper Chehalis Basin (upstream of Porter) and 91% of the lower basin (downstream of Porter), are generally located on the upland areas with scattered amounts on bottom lands. Most forested acres are corporation-owned with the remainder being privately or government-owned (Capitol State Forest, Mt. Baker-Snoqualmie National Forest and Olympic National Forest). Intensive agriculture and irrigation occur mostly in the low-lying valleys along the Chehalis River and its tributaries. Commercial farms in the basin are following national trends of increased acreage and reduced numbers. Primary use of agricultural land is for crop production (133,000 acres). Pasture comprises 1.8%, or 31,000 acres, of the basin (USDA, 1975).

The anadromous fish resources of the basin are of national significance to sport, tribal, and commercial fishing and are important to the economy of the Chehalis Basin.

Subbasin Descriptions

For the purposes of this plan, the Chehalis River Council has identified thirteen major subbasins comprising the Chehalis River Basin. The basin includes parts of eight counties and includes Water Resource Inventory Areas (WRIA) 22 and 23. A brief description of each subbasin follows:

A. - Upper Chehalis Drainage - above the Newaukum River

• The Chehalis River originates in southwestern Lewis County and flows northeast to the Chehalis-Centralia area. The Upper Chehalis drains about 438 square miles with an average annual discharge of 1,600 cubic feet/second (cfs).
  for Upper Chehalis details, click here.

B. - Newaukum River Drainage

• The Newaukum River originates in the eastern portion of the Chehalis Basin and flows westerly to join the Chehalis River near Chehalis at river mile (RM) 75.2. It drains a 158 square mile area, with an average annual discharge of 506 cfs.
  for Newaukum details, click here.

C. - Middle Chehalis - below Newaukum River and above Grand Mound, excluding the Skookumchuck River Drainage.

• The Middle Chehalis Subbasin above Grand Mound consists of the minor streams between the mouth of the Newaukum and the gaging station at Grand Mound. The total watershed area is 118 square miles, and the two principal tributaries are Lincoln Creek and Salzer Creek. The average annual discharge of the tributaries is 271 cfs and the drainage area is 118.0 square miles.
  for Middle Chehalis above Grand Mound details, click here.

D. - Skookumchuck River Drainage

• The Skookumchuck River rises in the westernmost region of the Mt. Baker-Snoqualmie National Forest and flows in a northwesterly direction to the town of Bucoda, and from there to a confluence with the Chehalis River at Centralia. With its tributaries, it drains 181 square miles. Much of the basin is in coniferous forest, but the river valley has some agricultural use. The average annual discharge from the basin is estimated to be 540 cfs. A major tributary of the Skookumchuck is Hanaford Creek with a drainage area of 58 square miles and an average annual flow of 85 cfs.
  for Skookumchuck details, click here.

E. - Middle Chehalis Drainage - below Grand Mound, between Grand Mound and Porter

• The Middle Chehalis - below Grand Mound, is that portion of the Chehalis Basin between the U. S. Geological Survey gage at Grand Mound and the gage at Porter, exclusive of the Black River Drainage. The watershed area is 263 square miles. The average annual discharge of the Chehalis River at Porter from January 1952 to September 1972 was 4,287 cfs.
  for Middle Chehalis below Grand Mound details, click here.

F. - Black River Drainage

• The Black River originates at Black Lake and flows in a southwesterly direction to join the Chehalis River near Oakville. It drains 136 square miles and has an estimated annual discharge of 330 cfs. Black Lake is included in this drainage, however the natural channel from lake to river is choked by vegetative growth and beaver dams. The Black River may actually originate from springs in this area south of the lake.
  for Black River details, click here.

G. - Cloquallum Creek Drainage

• The headwaters of Cloquallum Creek are about 6 miles north of McCleary, in Mason County. The stream flows southward about 20 miles to join the Chehalis at RM 25.2. The Cloquallum drainage area, with the inclusion of Wildcat Creek, covers an area of about 65 square miles. The average discharge of Cloquallum Creek is 375 cfs.
  for Cloguallum Creek details, click here.

H. - Satsop River Drainage

• The Satsop River originates in the southern part of the Olympic Mountains and flows southward to join the mainstem Chehalis River at RM 20.2 near the town of Satsop. The Satsop has four major tributaries: the East, West, and Middle Forks, and Decker Creek. The subbasin covers 299 square miles. The average flow of the Satsop is 1,968 cfs.
  for Satsop River details, click here.

I. - Wynoochee River Drainage

• The Wynoochee River has its headwaters in the Olympic Mountains and flows southerly to join the mainstem Chehalis River at RM 13.1 near the town of Montesano. The main tributaries to the Wynoochee are Schaefer Creek and Black Creek. The Wynoochee River drains a basin of 185 square miles. Rainfall averages range from 75 inches annually in the lowlands up to 220 inches annually in the Olympic Mountains. Retention time of subbasin runoff is characteristically short and river levels rise and fall rapidly. Since 1972, river flows have been regulated by the Wynoochee Dam about 46 miles upstream from the mouth. The average discharge is 1,316 cfs.
  for Wynoochee River details, click here.

J. - Wishkah River Drainage

• The Wishkah River Basin drains the southern slopes of the Olympic Mountains and covers an area of 100 square miles. Approximately 6 miles above Aberdeen, the East and West Forks of the Wishkah combine. They flow into the Chehalis Basin at RM 0.15. Average annual yield figures are unavailable.
  for Wishkah River details, click here.

K. - Hoquiam River Drainage

• The Hoquiam River originates on the southern slopes of the Olympic Mountain range and drains an area of 90 square miles. The East and West Forks and main branch all flow southerly and converge above the city of Hoquiam. The Little Hoquiam River flows eastward and joins the combined river about one-half mile upstream from the confluence with the East Fork. The river flows into Grays Harbor between the cities of Aberdeen and Hoquiam. No records for average flows are available.
  for Hoquiam River details, click here.

L. - Humptulips River Drainage

• The East and West Forks of the Humptulips River originate in the southwest portion of the Olympic National Forest and merge 4.5 miles above the town of Humptulips. The river flows southwesterly to Grays Harbor at North Bay. The Humptulips drains an area of 245 square miles. The average discharge is 1,344 cfs.
  for Humptulips River details, click here.

M. - Lower Chehalis Drainage - Below Porter

• The Lower Chehalis drainage includes the remaining area below Porter not included in the Cloquallum, Satsop, Wynoochee, Wishkah, Hoquiam, and Humptulips drainages. The total area of the Lower Chehalis Drainage is 169 square miles. The two largest creeks that merge with the Chehalis River (below Porter, but above the mouth) are Mox Chehalis Creek, which drains 27 square miles, and Newman Creek, with a drainage area of 23 square miles. The two largest rivers in this subbasin that empty directly into Grays Harbor are Johns River and Elk River. These rivers drain forested areas. Average annual discharge figures are unavailable for this subbasin.
  for Lower Chehalis Basin details, click here.