Siletz

Lower Drift Estuary

Regrowing lost habitats

Drift Creek flows into the Siletz Bay just south of Lincoln City, where it forms a beautiful estuary habitat. The area is now part of the Siletz Bay National Wildlife Refuge, but the habitat has been severely degraded in the last 150 years. Several partners are restoring the wetland’s natural functions by removing tidal flow restrictions, digging new channels for the tides to flow through, and promoting native plants.

 

The Lower Drift project aims to restore roughly 40 acres of tidal wetlands in 2023 through the removal of dikes, restructuring and connecting of tidal channels, creating small mounds and planting native species, placement of large woody debris (LWD), and controlling invasive species. An additional 40 acres will be restored in 2024. These restoration efforts added to 86 acres of previously restored wetlands within Siletz Bay National Wildlife Refuge.

The value of estuaries’ ecosystem functions have not been prioritized in recent history. Instead, Oregon’s tidal wetlands have been diked, ditched, developed, or grazed to the point that the area of Oregon’s tidal wetlands has declined by an average of about 60%.

Once a common habitat along the Oregon Coast, forested swamps have declined by an average of roughly 95%. New research shows that forested swamps provide important ecosystem services such as shelter and foraging grounds for salmonids, multi-layered wildlife habitat and stream shading, and high levels of carbon storage in the soil. 

  • Wetlands are areas where water covers the soil, or remains close to the surface all or most of the year. Both marshes and swamps are types of wetlands. Marshes are wetlands that are dominated by soft-stemmed plants such as grasses. Swamps are wetlands that are dominated by woody plants such as trees or shrubs.

A forested tidal swamp (Photo by Laura Brophy)

In addition to directly supporting the preservation of estuary wildlife, the Lower Drift project plays a part in strengthening Oregon’s coastal climate change resiliency. Estuaries have a built-in system to adapt to rising sea levels. As sediment flows into the estuaries from the tides and river, it collects in vegetation and increases the elevation of the wetlands. Estuaries are also “blue carbon” ecosystems (such as mangrove forests and seagrass beds) which are even more efficient at storing carbon from the atmosphere than tropical forests!

How?

  • Improving topographic diversity higher elevation spots for spruce and native shrubs are present.

    Placing LWD to create potential nurse logs.

    Planting of spruce and native shrubs and managing invasive species. 

  • Removing tidal flow barriers such as old dikes, culverts, and riprap to allow for natural deposition of sediment.

    Placing of LWD to aid in catching of sediment.

    Creating elevation gradient to promote sediment deposition.

  • Increasing tidal channel connectivity through channel shaping and removal of tidal flow barriers.

    Placing of LWD to create shelter for aquatic species and coastal birds alike.

    Planting of native plants.

 

The first phase of the Lower Drift restoration began the summer of 2023 when stream diversion and fish salvage took place in July prior to the restructuring of tidal channels using large machinery. During fish salvage, species such as shiner perch, greenling, rockfish, gunnel, stickleback, and Coho salmon were successfully salvaged from the active work area and safely moved to habitat downstream. 


Project partners include US Fish and Wildlife Service, Oregon Coast National Wildlife Refuge Complex, US Forest Service, Bureau of Land Management, private landowners, the Lincoln Soil and Water Conservation District, the Wild Salmon Center, National Oceanic and Atmospheric Administration, and the Confederated Tribes of the Siletz Indians.

To learn more check out these resources:

 

North Creek

Prime salmon habitat reconnected

In 2019, a large culvert was put in place on North Creek, a tributary to Drift Creek in the Siletz River Basin, that allows salmon, steelhead, coastal cutthroat, lamprey, freshwater mussels, and other organisms to freely access sixteen miles of stream and wetland habitat for the first time in 62 years.

Contractors removed the old, severely undersized culvert and installed an appropriately sized, open-bottomed structure that doesn’t create a barrier to fish and other animals or to the downward transport of gravel or large wood which improves salmon spawning grounds downstream. The culvert replacement also allows for safe transport to and from popular forest recreation areas and Drift Creek Camp

Other collaborators assisted with funding, including the USFS, the U.S. Fish and Wildlife Service’s Fish Passage Program, Oregon Watershed Enhancement Board, Oregon Department of Transportation-Oregon Department of Fish and Wildlife Fish Passage Program, Trout Unlimited, National Fish and Wildlife Foundation, as well as a crowdfunding campaign organized by the Native Fish Society. 

Before (1980s)

After (2020)

The follow up

Students in Oregon Coast Community College’s Freshwater Habitats course are assisting in the data collection to determine how the new culvert is affecting the physical aspects of the stream and identify how organisms like salmon and aquatic insects respond to the newly opened channel. Volunteers with Trout Unlimited will continue eDNA sampling at 13 locations in the North Creek Watershed for two more years to determine the presence of difficult-to-survey target species such as lamprey and freshwater mussels. The efforts of these community partners will be complemented by stream temperature monitoring for three years by the USFS and the Environmental Protection Agency. The data resulting from monitoring work is expected to serve as an example for future large-scale aquatic organism passage projects.

OCCC students looking at samples in lab

OCCC students analyzing stream channel

Substrate change surveys

To learn more about this project, check out its coverage in the local news:

For even more nitty, sometimes gritty, details of what occurred throughout the nearly $1 million project’s timeline, click on the buttons below for bi-monthly breakdowns written by project partners as the work was happening:

Mill Creek

When large trees fall into a stream, they divert the energy of water and create complex arrangements of pools and riffles that are crucial for young salmon and other animals to survive. Extensive logging and human alteration has dramatically reduced the amount of wood and complexity in streams.

Pool created by large conifer wood placement under an alder forest.

In partnership with ODFW, MCWC installed 679 logs in 6.8 stream miles of salmon habitat in Mill, Gunn, and Cerine Creek. The goal of this project was to restore habitat complexity for young salmon. Large wood accumulates spawning gravel, provides substrate for prey to grow, and creates deep pools and slow water for young fish to live in.

Map of Large Woody Debris sites (LWD), Temperature, Life Cycle Monitoring (LCM), and Benthic Macro Invertebrate (Macro), and geomorphology site (Geo) locations.

Because the mouth of this basin has housed ODFW’s Life Cycle Monitoring (LCM) site for over 20 years, there is long term data about the numbers of juveniles and returning adults in this area. Strong before and after data make this project an excellent opportunity to study the effectiveness of projects like these.

This project is being followed up by an extensive Effectiveness Monitoring project to determine the effects of the large wood placement on fluvial geomorphology, aquatic habitat, benthic invertebrates assemblages, overwinter survival of juvenile coho, and overall coho smolt production for the watershed.

Field tech conducting Aquatic Habitat Inventory study.

Partners include: ODFW, Weyerhaeuser, Oregon DEQ, and OSU College of Forestry. The study is designed to inform future in-stream restoration priorities, large wood placement design, land use management, coastal coho recovery goals and objectives, and limiting factors analyses for coho salmon production.