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This is a Washington State extract downloaded from the USGS in February 2018 and projected into WA State Plane Coordinates South. Strahler Stream Order has been added. The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's surface water drainage system. This high-resolution NHD, generally is developed at 1:24,000/1:12,000 scale, but many areas of Washington State have been improved to 1:4800 scale. NHD data was originally developed at 1:100,000-scale and exists at that scale for the whole country. Local resolution NHD is being developed where partners and data exist. The NHD contains reach codes for networked features, flow direction, names, and centerline representations for areal water bodies. Reaches are also defined on waterbodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria established by the Federal Geographic Data Committee. Stream Orders in Washington State range from 1 to 10. The smallest headwater streams are a 1, and the Columbia River is a 10.
This feature class contains a BETA version of Water Type attached to the Skagit River Basin NHDFlowline. This Beta version of the Water Type is the result of a pilot project and will be refined over the next six months. The field is for users of NHD who want access to Water Type and who are not under Forest Practices rules. The Water Type uses Shorelines Master Program type S streams and Fish Presence Data from both WA Dept Natural Resources and WA Dept Fish and Wildlife.
This data includes the results of the SUMMARY steps in modeling the assessment of the water quality process (Sediment, Phosphorus, Metals, Nitrogen, and Pathogens) for analysis units in a WRIA/sub-watershed. For a complete description of the overall water quality model and each attribute, see the Department of Ecology publication # 11-06-016, Puget Sound Watershed Characterization, Volume 1: the Water Resource Assessments (Water Flow and Water Quality).The water quality assessment is the result of a modeling approach to assess the areas of relative export potential (Model 1) to the water quality process and the relative degradation (Model 2) to the process from human activity among analysis units across a watershed (WRIA). It is a broad scale analysis to identify areas on the landscape that are most important for maintaining the water quality process, and to characterize the degree of degradation to the process from human activity. The results can help to identify areas that are : 1) more important to protect, 2) a higher priority to restore, and 3) more appropriate for development. It is best suited to analysis at the watershed or sub-watershed scale, or tens to hundreds of square miles, with individual analysis units being in the range of approximately one to fifteen square miles. It is not intended for use at the site scale.