Natural Features & Ecosystems

ESRI Story Map on Tidal Wetland Restoration at Lewis and Clark National Historical Park

By: Kayla Fermin

Nature and Science
Recovering coniferous forest

NPS photo

Prior to the early 1800s the Fort Clatsop site was predominantly old growth Sitka spruce forest. Logging removed all of the site’s old growth between 1850 and 1900. By 1950 some forest cover had been restored. Most of the originally forested area had been replanted by 1988, primarily to western hemlock and Douglas fir. The return of a mature or old-growth Sitka spruce/western hemlock forest similar to the one encountered by the Lewis and Clark Expedition in 1805-06 is a high priority for the park and an objective listed in the General Management Plan.

Approximately 50% of the park is freshwater or estuarine wetlands. Ten types of wetlands occur within the park, as identified by the National Wetland Inventory.

Water within and surrounding the park has been greatly diverted and altered. The Lewis and Clark River has been extensively diked for flood control, reducing or eliminating fertile floodplains. The former floodplains are now utilized for agriculture and development. Logs, rootwads and other woody debris have been historically removed from the river to improve its navigability, increasing its flow rate and decreasing wildlife habitat quality. Many activities within the Lewis and Clark River drainage may impact Fort Clatsop’s water quality and wetlands. These activities include pesticide and fertilizer use, runoff from agricultural and logging operations, potential contamination due to tidal influences (such as oil spills), illegal dumping of household and industrial rubbish and toxic materials, erosion from forest roads and logging operations, and encroaching development.

The North Coast and Cascades Network (NCCN) Inventory & Monitoring Program has been monitoring tree mortality and recruitment in mature forests at Cape Disappointment since 2014. Learn more about this program and read about our findings on the NCCN Forest Monitoring Website.

Map of Restoration Project

Restoration at Lewis and Clark National Historical Park

South Clatsop Slough Restoration Project


The South Clatsop Slough Restoration Project is in the recently expanded Fort Clatsop unit of the Lewis and Clark National Historical Park. The project site is located between the Fort Clatsop Visitor Center and Netul Landing, along the Lewis and Clark River approximately 1 mile upstream from the confluence with Youngs Bay. The project is approximately 47 acres.


The project goals are to:
  • Protect the property in perpetuity as a part of the National Park Service unit.
  • Reconnect the former slough with the Lewis and Clark River and Columbia River Estuary.
  • Reestablish estuary habitats on approximately 47 acre of land. Habitat that will be created includes riparian, emergent marsh, stream channel and Sitka Spruce marsh.
  • Use the site as outdoor laboratory for research and education.

The acquisition of the property that contains South Clatsop Slough has increased the National Park Service’s ability to manage the lands in the park to restore ecological process, provide recreational and educational opportunities. This project will restore approximately 47 acres of marginal pasture land to a part of the Columbia River estuary.

The project is starting with planning, engineering and design that will in turn direct the work to reestablish the connection between the slough and the Columbia River estuary. It is envisioned that the planning and engineering will call for the removal of structures and fill to create this connectivity and enhance the habitat.

As part of the initial work extensive surveys are being conducted to establish base line conditions. This data and monitoring stations will allow scientists and teachers to study, learn and teach about the changes that will take place. Studies now underway include: channel geometry, vegetation communities, water quality, topography, fish species, and current tidal elevations. This information will be used to drive the design of the engineering plans and contract specifications for the work to create the wetlands. It is expected that the data sampling will be repeated through time to measure the changes over years.

The slough is part of a small watershed (approximately 540 acres) that is entirely within the Lewis and Clark National Historical Park. The watershed is comprised of this slough and uplands that were until recently managed as commercial timberlands. Given that the entire watershed is within the boundary of the park makes the project ideal for estuary enhancement without creating concerns for impacts to adjacent landowners.


By reconnecting the slough to the estuary, the site is expected to change from a marginal pasture to a mix of estuary habitats. This means moving towards a stream channel with native aquatic vegetation, emergent wetland and marsh habitat, stream riparian habitat and Sitka spruce swamp. These different vegetation types provide important habitat for wildlife. This includes, but is not limited to, habitat for; salmon, cutthroat trout, white sturgeon, beaver, river otters, and muskrats, bald eagles, osprey and great blue heron. With more food and cover resident animals such as elk, black bear and mountain lion will make greater use of the watershed.

The project is also expected to serve as an outdoor laboratory for scientists and teachers. Scientists will be able to monitor the changing conditions at the project site and this in turn will help them to evaluate the effectiveness of the restoration techniques used. Teachers and families will be able to use the site to learn about the native habitat and wildlife, about restoration science and the ecology of the region.


  • The Conservation Fund initially purchased the property and has provided $150,000 grant.
  • The Lower Columbia River Estuary Partnership provided a $150,000 grant.
  • The North Coast Land Conservancy has provided $18,000 in grants for the project.
  • The Port of Portland has provided a $10,000 grant to help with the project.
  • The Columbia River Estuary Task Force (CREST) is managing the restoration project in partnership with the National Park Service.
  • Clatsop County Road Department, Youngs Bay Watershed Council, Youngs Bay Diking District are all providing technical support.
  • Mr. and Mrs. Ness, the previous landowner, demonstrated great patience in working to have this property become a part of the park.

Last updated: May 6, 2020

Contact the Park

Mailing Address:

Lewis and Clark National Historical Park
92343 Fort Clatsop Road

Astoria, OR 97103


(503) 861-2471
Rangers are available to answer your calls between the hours of 9 - 5 PST.

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