Older Culvert (IMAGE) University of Washington Caption An example of a culvert before upgrades. This concrete pipe creates a big drop that is hard for salmon swimming upstream. Washington is legally obligated to upgrade these culverts to preserve treaty rights and protect salmon species under a 2013 federal court ruling. 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.