Intact riparian ecosystems are key to maintaining and restoring fully functional stream habitat.
Healthy riparian zones, or areas of vegetation along stream banks, play a central role in creating habitat for aquatic species. Intact vegetation helps provide shade - cooling stream temperatures, reduces stream bank erosion, and also acts a buffer, filtering run-off of nutrients and sediment from surrounding land. Additionally, trees and other plants that fall into the stream from vegetated banks are an important source of nutrients and help create in-stream habitat complexity, allowing organisms spaces to hide from predators.
Over the past hundred and fifty years, much of the riparian zone in areas of tidal wetlands has been lost as wetlands have been drained and streams have been channelized. Before settlement, these systems were sinuous and marshy, providing highly productive rearing areas for juvenile salmon, including coho. As the stream network has been simplified to accommodate agriculture land and other forms of development, only about 10% of Coos Bay's original tidal wetlands remain (source). This dramatic loss of habitat makes it all the more important to ensure that what lowland streams and marshes do remain are fully functional. Functionality in these systems additionally means working with agricultural stakeholders to return fields that experience frequent flooding to productivity. In addition to restoring lowland riparian zones, CoosWA also addresses upland streams that may have impacted riparian zones due to historical logging practices (buffer zones are now required). The tools and practices that CoosWA uses to restore functionality to riparian zones typically fall into one of three categories: planting, fencing, and erosion control. These techniques are frequently combined with sediment reduction projects, long-term monitoring efforts, and in-stream restoration projects to holistically restore streams.
Riparian restoration methods are highly variable depending upon the eco-region, the location in the watershed, and the specific site characteristics of the restoration project. On the Oregon Coast, allowing natural regeneration to restore the site is rarely successful due to the rampant and highly competitive nature of invasive riparian plant species. Under such conditions, restoration of riparian areas usually involves very specific planting techniques and a well coordinated post-planting maintenance regime. Additionally, each planting plan is site dependent and designed to augment existing populations of native plants rather than introduce plants that are not already established in that area. All trees and shrubs used in planting projects are sourced from or prepared for planting at CoosWA's own Matson Creek Native Plant Nursery.
The CoosWA restoration team and Summer Restoration Youth Crew members build many types of fence ranging from electric, standard, and stock wire to pedestrian fencing (safety rails). Riparian fencing is commonly installed to provide ease of access to streams for deer, elk, and other wildlife while keeping livestock in designated areas. Preventing heavy animal traffic along streams is also necessary to allow a native riparian buffer to re-establish, as heavy impact can damage young shoots.
CoosWA crews apply erosion control techniques to all disturbed soils on CoosWA restoration projects involving state, federal, and private agencies. Erosion control commonly occurs in late summer to minimize soil loss and improve waters quality during winter storm events. Certified weed free straw and seeds are used at each site. High strength mesh netting is additionally used on root wads, willow saplings, and other native plants to create a protective barrier and prevent grazing by deer or elk. Once trees and shrubs are established, they help stabilize stream banks and reduce the likelihood of soil loss. Strategic planting and staking are crucial in protecting riparian areas and preventing heavy sediment input into nearby streams.