The Washington State DOT (WSDOT) has negotiated with its Department of Ecology, a permit which allows the DOT to wash four over-water bridges in a trial to determine the appropriate conditions under which future bridge washing should be permitted.
Download the WSDOT’s NPDES Bridge Permit.
The Maine DOT has also developed a Best Practices agreement with its Department of Environmental Protection for the cleaning and washing of bridges. The agreement may be viewed at http://www.maine.gov/mdot/community-programs/csd/localbridgemaintlw.php