Skip to main content

Willamette Mainstem Cooperative

Who We Are

The Willamette Mainstem Cooperative (WMC) is a collaboration of landowners, organizations, and volunteers working together to promote, facilitate, and foster long-term stewardship of Willamette River resources with a focus on the Corvallis to Albany river reach.

What We Do


We collaborate with stakeholders to raise awareness about native and invasive plants along the river and address weed control priorities.

May contain: logo and person

We provide information and opportunities for people to work together to achieve shared goals for river health.


We plan for the short and long-term management of aquatic and terrestrial invasives and PRIORITIZE species focus based on invasive plant population size and habitat impacts.

We surveyed close to 3,000 acres of riparian and aquatic habitats between Corvallis and Albany to identify high quality habitats and map populations of priority invasive plants.

Species Found in Small PatchesSpecies Abundant, Yet ControllableHigh Quality Habitat
Japanese KnotweedEnglish Ivy~15% or 385 acres of area surveyed
Purple LoosestrifeFalse Bromemostly on public land
Scotch BroomWater Primrose speciesmostly in relatively undisturbed sites
Spotted KnapweedOld Man's Beardpatches average six acres



We protect high quality habitat through control and containment of target invasive plants.

We apply integrated techniques to control priority invasive plants on the Willamette River. Efforts have spanned from volunteer weed pulls to technical control methods implemented by contracted and licensed experts.


We monitor post-treatment site changes for impacts, success, and future management needs.

2016 Monitoring Report2017 Monitoring Report

We plant and encourage natural recruitment of appropriate native aquatic and terrestrial plant species following invasive weed control treatments.



This project would not have been possible without the help of the following organizations:

May contain: logo