The Chehalis River drains a vast area of western Washington, forming the largest river basin in the state, after the Columbia. Fed by rivers and streams that flow from the Cascade foothills, the Willapa Hills, glacial prairies of the northeast and the Olympic Mountains, the Chehalis eventually drains into Grays Harbor on the Pacific, where it forms the largest, highest-quality tidal surge plain in Washington. Here, where salt water from the Pacific surges inland with the tide to meet the freshwater of the Chehalis River, a diverse and highly productive wetland ecosystem is formed.
In the Chehalis River Surge Plain, sheltered sloughs provide crucial habitat for a wealth of fish and wildlife, including spring and fall Chinook, coho, chum salmon, steelhead, river otter, beaver and the endemic Olympic mudminnow. Dense stands of Sitka spruce and western red cedar, draped with mosses and lichens, are home to bald eagle, osprey and other bird life. All year long, hikers and paddlers visit the area to explore the tidal channels by foot, canoe and kayak.
There are only four other wetlands of this type in Washington, all of which are substantially smaller and in poorer ecological condition than the Chehalis River Surge Plain. In 1989, the Washington Department of Natural Resources created the Chehalis River Surge Plain Natural Area Preserve to protect this important ecosystem. Yet, for almost 30 years, the preserve has been incomplete, with nearly 1,500 acres at the heart of it privately owned and unprotected. In partnership with the Weyerhaeuser Company, Western Rivers Conservancy has taken the first steps toward completing the preserve and ensuring the lasting integrity of this extraordinary place. Together, we will conserve 1,472 acres of former timberlands by transferring them to the WDNR for inclusion and protection within the natural area preserve.
WRC’s efforts will benefit the river, its wildlife and the thousands of people who visit each year by completing the original vision for the preserve and eliminating the threats of development and timber harvest. The project will conserve more than six miles of river frontage, including exceptional water-trail systems through Peel’s Slough, Blue Slough and Preachers Slough. Canoe and water trails will be joined to upland parcels, and both scientific and educational activities will be enhanced. And once WDNR acquires these lands, the Chehalis River Surge Plain will be protected not in fragments, but in its entirety.
The Chehalis River Surge Plain Natural Area Preserve is managed by the Washington Department of Natural Resources and is open to the public. The NAP spans 3,018 acres just upstream from where the river empties into Grays Harbor and will total nearly 4,500 acres of protected land when WRC’s efforts are complete.
Visiting the preserve is a wonderful way to explore the extraordinary and increasingly rare estuary environment, where fresh and salt water systems come together to create tidal wetlands. The southern edge of the floodplain can be explored by foot, while having a canoe, kayak or stand-up paddleboard will allow you to get into the heart of the preserve and explore its many sloughs.
There is one hiking trail, which follows an abandoned railroad bed for 3.5 miles along the southern reaches of the preserve. The trail passes Blue Slough and Preachers Slough and has multiple interpretive signs along the way, which explain the natural systems at work in the surge plain. They also provide information on the plants, animals, fish and insects that inhabit this special place, where seawater and river meet. The first half-mile of trail is gravel and leads to an observation platform at Preacher’s Slough. A rougher-surfaced interpretive trail continues for 3 miles along Blue Slough.
For paddlers, there are two sites for launching a canoe, kayak or other small paddle-craft. One is at Preacher’s Slough (past the first parking area) and the other is off of Blue Slough Road.
In addition to the trail and signs, the site offers toilet facilities and a parking lot at the Preachers’ Slough access.
The preserve boundary includes much of the flood plain area between river miles 3.8 and 10.5 of the Chehalis River. From Montesano, at the junction of U.S. 12 and Highway 107, travel south and west on Hwy 107 for 3.9 miles. Turn right at Preacher’s Slough Road. Trail parking and toilet facilities are on the left, and water access is further down the road. Here is a Google Maps link.
A Washington State Discover Pass is required for parking at this site. This funding helps DNR manage these important natural areas across the state.