Description: The U.S. Environmental Protection Agency's (EPA) Reach Files are a series of hydrographic databases of the surface waters of the continental United States and Hawaii. A key characteristic of the Reach files are their attributes that define the connected stream network. These attributes provide connectivity regardless of the presence or absence of topologic continuity in the digital linework. Flow direction is inherent in the connectivity attributes. This attribute-level connectivity enables the Reach Files to provide hydrologic ordering of stream locations using reach codes (what is upstream and downstream of a given point in the stream network) as well as network navigation proceeding in either the upstream or downstream direction. RF3-Alpha data is un-validated and given the nature of the shortcomings that have been identified in the RF3-Alpha data and the re-design work that is being incorporated into RF3 validation to support GIS applications, it is recommended that a conservative approach be taken when processing and applying these data. The final, validated RF3 ("The National Hydrography Dataset") will provide a much improved data product. In the mean time, access to the provisional Alpha data, accompanying documentation, and technical support is provided through the Office of Water's (OW) STORET User Assistance Group. STORET, EPA's national water quality data system, is currently undergoing a major re-design to address evolving user requirements and technology advancements including GIS. Both STORET and RF3 will play integral roles in EPA's future water quality data collection, analysis, and reporting activities. For further assistance on RF3 Alpha, please contact STORET User Assistance at 800-424-9067.
Copyright Text: McKay, Lucinda; Sue Hanson; Robert Horn; Richard Dulaney; Alan Cahoon; Mark Olsen; and Thomas Dewald, 1994. The U.S. EPA Reach File Version 3.0 Alpha Release (RF3-Alpha) Technical Reference. U.S. Environmental Protection Agency, Washington, DC