This process has all but eliminated the natural pool-riffle morphology with a consequent loss of aquatic and riparian habitat. The design approach involved removing the plug that blocks flow into the secondary channel, thereby reducing the flow velocity by nearly one half in the main stem channel. The reduction in velocity and energy will allow sediment to aggrade the main channel, thereby encouraging a natural pool-riffle morphology. In order to provide a catalyst for the aggradation process, the design included construction of log and rock weirs in the main stem channel. Enhancements on the side channel include log and boulder weirs to provide grade control, and placement of rootwads. The project was constructed in September 2009.
Gooseneck Creek Restoration
Client: Yamhill Basin Council
Waterways staff prepared the engineering design documents to reactivate a historic secondary channel on Gooseneck Creek and encourage bed aggradation through a bedrock reach. The project is located above the confluence with Mill Creek in Polk County, Oregon. The secondary channel was plugged during gravel mining operations over the last several decades. The effect on the main stem channel has been an increase in flow velocities and energy and subsequent downcutting of the creek to bedrock.