Recently, Environmental Services installed new plants in southwest Portland at the mouth of Stephens Creek and the Willamette River. This is follow up work for the Stephens Creek Confluence Habitat Enhancement Project.
This revegetation work is unique because we’re using a product developed by a company in Idaho that is fairly new here in Portland - wetland sod mats. The mats were delivered to the project site by boat, then were unrolled and staked down in place.
The woven coconut coir mesh mats have a variety of wetland plants incorporated into them, such as rice cutgrass, hard stem bulrush and Columbian sedge. They are grown hydroponically during the spring and summer before they are planted at a project site in the fall. The goal is to create wetland sod mats with strong root systems that can help prevent erosion and provide a diverse pallet of native vegetation.
At places like the Stephens Creek Confluence, where a stream that is prone to high flows meets a dynamic river like the Willamette, strong currents can cause young plants to wash out of new restoration areas. On the other hand, when native plants become well-established, restoration sites can become relatively self-sustaining and require little City maintenance in future years. Environmental Services is using these innovative wetland mats to help stabilize the Stephens Creek Confluence site, and will be applying any lessons learned from this to future restoration projects.