The Washington State Department of Transportation (WSDOT)/University of Washington Highway Runoff Water Quality research project, conducted from 1977 to 1982, produced a number of results of potential use to WSDOT. An effort was required to implement these results in the Department's procedures. One phase of implementation completed previously involved preparation of a guide for assessing the impacts of operating highways on aquatic ecosystems and training WSDOT personnel in its use. The present phase involved formulating decision criteria in a number of water quality problem areas of concern to WSDOT and determining the need for revisions to departmental documents for consistency with the research results and the new criteria. The results of this phase are presented in a two volume implementation manual and a separate document listing the suggested modifications to four existing WSDOT manuals. Volume 1 of the implementation manual states the criteria, which were developed for: 1) identification of waters potentially sensitive to impact by operating highways; 2) the use of vegetated drainage courses to treat highway runoff; 3) the use of retention/detention facilities for highway stormwater drainage; 4) disposal of ditch cleaning spoils; 5) the use of woodwaste fills for highway construction; 6) highway sanding; 7) dilution of highway runoff in a receiving water; 8) highway cleaning; 9) stream channel modification for highway construction. Volume 2 presents the basis of each criterion listed in Volume 1, including references to the research results and other literature, the reasoning followed, development of equations, etc.