Students from Timber Lake Job Corps and the sunshine joined us once again last week at Currin Creek. We were also joined by our project funders, Clackamas County Soil and Water Conservation District staff.
Currin Creek, which flows behind Estacada High School, was altered during construction of a ball field behind the school, causing erosion. Pacific Habitat Services did bank work to regrade the steep eroding banks and volunteers. Estacada High School students, Timber Lake students, and community volunteers have been working with SOLVE to prevent further erosion by planting thousands of native trees and shrubs and constructing some bioengineered brush dams.
As applied to riparian restoration, bioengineering is a branch of engineering in which green woody plants are an integral part. Living plants and cuttings of plant stems are propagated and used as building materials for controlling erosion as well as for riparian restoration.
Timber Lake students constructed 10 bioengineered brush dams made of bundles of Willow, Black Cottonwood and Red Osier Dogwood branches which will root into the stream bed, providing soil stability. The dams slow down the flow of the stream and trap sediment behind them to build the stream bed back up and prevent erosion.
Conventionally, engineers have used only static inorganic materials that provide neither habitat for fish and wildlife, nor shade for the stream. Bioengineering techniques include effective, low cost methods for protecting and restoring riparian areas. Different species of willows and cottonwoods are used widely for bioengineering projects because they easily form roots on stem cuttings.