Upgraded Culvert (IMAGE) University of Washington Caption The completed culvert replacement at state Route 11 in Bellingham. The new stream bed is broad with a gradual gradient. Tree trunks in the foreground act as woody debris to provide a more natural flow to help salmon swimming upstream. Credit Elizabeth Andruszkiewicz Allan/University of Washington Usage Restrictions With credit License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.