The William H. Nelson papers on Colorado Water cover issues related to the Colorado River watershed, with an emphasis on the Western Slope. Materials include correspondence, photographs, government documents, press releases, brochures, publications, newsletters, and other documents related to the management of water in the Colorado River basin from the 1860s to the 1990s with the majority of the content focused on the 1940s into the 1980s. The material focuses heavily on Bureau of Reclamation water projects, especially the Colorado River Storage Project (CRSP) and the Fryingpan-Arkansas Project. Legal battles over water rights between the Eastern slope and the Western Slope of Colorado as well as between the Federal government and the states figure heavily as well. Other topics covered include water quality, stream salinity, and hydrological forecasting using snowpack.