Ecology created the GIS statewide river mile point layer in March 2007 by digitizing the river mile points depicted on the USGS 7½ minute (24k) topographic quadrangle maps. Some of the rivers have gaps in the river mile progression because several of the quadrangle maps do not have any river mile points, while a few were missing a point or two. In November 2014 Ecology added river mile points for the missing areas using Washington Department of Fish and Wildlife's (WDFW) 1975 Stream Catalog, which only covers WRIA's 1 through 24. The Stream Catalog shows river miles for nearly every stream; however, only those water courses that have river miles from the USGS quadrangle maps were added. The field SOURCE denotes the source of the data point, USGS or WDFW. Discrepancies between the USGS and WDFW are documented in the Supplemental Information section.