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The EPA Reach File: A National Spatial Data Resource

Thomas G. Dewald
Office of Wetlands, Oceans, and Watersheds
Office of Water
U.S. Environmental Protection Agency
Washington, DC

and

Mark V. Olsen

Environmental Monitoring Systems Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, Nevada

May, 1994

Abstract

The Environmental Protection Agency's (EPA) Reach File (Version 3.0), known as RF3, is a national hydrologic database that interconnects and uniquely identifies the 3.2 million stream segments or "reaches" that comprise the Country's surface water drainage system. RF3 is being developed by the EPA's Office of Water from U.S. Geological Survey (USGS) 1:100,000 scale hydrography data. The RF3 production process assigns a unique reach code to each stream segment contained within the USGS hydrography and determines the upstream/downstream relationships of each reach, allowing them to be connected together to form a national hydrologic transport network. The reach codes provide a common nomenclature for Federal and State reporting of surface water conditions as required under the Clean Water Act. In addition, the hydrologic transport network defined within RF3 enables the modeling of waterborne pollution associated with both point and non-point sources. This paper presents the current status and plans for RF3 development.

Background ("How did we get here from there?")

The U.S. Environmental Protection Agency's (EPA) Reach File (Version 3.0), known as RF3, is a national hydrologic database that interconnects and uniquely identifies the 3.2 million stream segments or "reaches" that comprise the Country's surface water drainage system [HORN0594]. RF3 is being developed by the EPA's Office of Water from U.S. Geological Survey (USGS) 1:100,000 scale hydrography data. The RF3 production process assigns a unique reach code to each stream segment contained within the USGS hydrography and determines the upstream/downstream relationships of each reach, allowing them to be connected together to form a national hydrologic transport network.

The reach codes contained within RF3 uniquely identify, by watershed, the individual components of the Nation's rivers and lakes. These codes provide a common nomenclature for Federal and State reporting of surface water conditions as required under the existing Clean Water Act such as the biennial National Water Quality Inventory report to Congress as mandated under Section 305(b) of the Act [CLIF1193]. It is also highly likely that the re-authorized Clean Water Act now under consideration by Congress will include more specific geographically-based reporting requirements. In addition, the hydrologic transport network defined within RF3 enables the modeling of waterborne pollution associated with both point and non-point sources. Integrating data from government organizations at all levels by linking them to this nationally consistent hydrologic network will allow permit writers, emergency management personnel, and other environmental managers to "navigate" upstream and downstream when assessing the causes or implications of actual or potential pollution events, e.g., spill contingency planning and emergency response, pollution dispersion modeling.

RF3 benefits from strong support provided by a variety of collaborating organizations. The EPA's Office of Water (OW) has overall programmatic responsibility for the development and support of RF3. The Office of Administration and Resources Management (OARM) manages the EPA's National GIS Program and plays the leadership role in coordinating its spatial data resources. The EPA's Office of Research and Development (ORD) has teamed with OW and OARM's Office of Information Resources (OIRM) during the past few years to establish GIS access to RF3 and to address the associated issues related to managing corrections and enhancements made to the File. It was this desire to develop a bi-directional software bridge between RF3's home on the EPA's IBM mainframe computer in Research Triangle Park, North Carolina and local GIS workstations across the Country that led to the establishment, by these EPA Offices, of the RF3 Workgroup. The U.S. Geological Survey's (USGS) Water Resources Division and National Mapping Division are also actively participating in this effort, while numerous states have contributed to RF3 development including Arizona and California which each provided preprocessed 1:100,000 scale hydrography for its production. The RF3 Workgroup provides for interagency coordination in the RF3 production process.

Status ("What are we up to now?")

RF3 production is generally described as a two-step process which entails the initial compilation of spatial and attribute data from a variety of different sources and the subsequent validation of the resulting file to ensure the integrity of the reach codes and hydrologic connectivity that define RF3.

The compilation part of RF3 production involves the combining of relevant portions of the Reach File Versions 1.0 and 2.0 (RF1 and RF2, respectively), the USGS Geographic Names Information System (GNIS) database, and the 1988 USGS 1:100,000 scale Digital Line Graph (DLG) hydrography [DEWA0285]. This processing employed custom mainframe and personal computer software and was designed to deliver enhanced capabilities to traditional Reach File mainframe and PC users. RF3 compilation is complete for the conterminous United States and Hawaii, except for the Pacific Northwest (PNW) region that includes Idaho, Oregon, and Washington. Concurrent with and independent of the RF3 compilation effort, a consortium of Federal and State organizations in the PNW jointly developed a Reach File-like hydrologic database using the USGS 1:100,000 scale hydrography and carrying forward many of the design features and reach codes defined within RF1. We have recently renewed discussions with the PNW coordination group in hope of developing a plan for reconciling RF3 and the PNW hydrologic database. In addition, we plan to produce RF3 data for Puerto Rico and, possibly, the Virgin Islands in the near future and are presently conducting an RF3 pilot project with the Bureau of Land Management in Alaska.

During the early 1990's, RF3 production was slowed considerably due to the attrition of several key EPA Office of Water staff while compilation was underway. It was during this time that the RF3 Workgroup was formed by OW, ORD, and OIRM to address the use and enhancement of RF3 within GIS. OW's interest in capturing GIS modifications to RF3 data prompted the decision to limit access to RF3 while update management procedures were being developed. Subsequently, the discovery of a variety errors in RF3 primarily by participating GIS cooperators, e.g., DLG density variations, coordinate shift, incorrect watershed assignment, re-emphasized the need to follow through with a rigorous validation of the File. Coincident with the recent return of RF3 support staff this past fall, the Office of Water has initiated efforts to assess and revise RF3 as part of this validation effort. This validation processing will also provide an opportunity to address expected errors introduced during the essentially blind compilation process that were not corrected at that time due to resource constraints. The assessment phase of RF3 validation involves the investigation of errors reported by users and an evaluation of data content and internal relationships. The revision phase will employ both batch (blind) and interactive (visual) procedures to resolve, where feasible, the highest priority items identified during assessment. Several basic design concepts, such as open water representations, are also being re-visited at this time in an effort to make RF3 more useful in GIS applications. It is anticipated that RF3 will be completed and released sometime during 1995.

As part of RF3 validation processing, EPA is coordinating closely with USGS NMD and WRD to synchronize RF3 feature definitions and linework with the hydrologic component of the new USGS Digital Line Graph Enhanced (DLG-E) product. This collaborative effort will minimize duplicative work and better enable both organizations to maintain and enhance their respective data sets.

Plans ("What does the future hold?")

The relevance of nationally consistent digital databases to improved natural resource management and environmental protection is evidenced by the ongoing deliberations aimed at establishing the National Spatial Data Infrastructure (NSDI). The OMB-sanctioned Federal Geographic Data Committee (FGDC) was recently tasked by Executive Order of the President with developing the NSDI to promote and insure proper spatial data coordination and management across the country. The NSDI will be comprised of core "framework" data sets including hydrology. RF3 has been nominated to serve as the hydrologic framework for the NSDI with RF3 reach codes as the permanent identifiers for the Nation's surface water features. Equally, if not more, important the Clean Water Act is currently undergoing re-authorization and will assuredly place increased significance upon responsible management of our water resources on a watershed basis. In recognition of this growing emphasis upon geographically-based management practices and the underlying requirement for spatial data to support them, EPA's Office of Water is pursuing with renewed commitment the completion of RF3 and planning for its long term maintenance and support.

In preparation for the planned completion of RF3 this coming year, a conceptual design document for the Reach File Update Management System (RUMS) has been completed as well as a complementary set of prototype GIS-based RF3 update tools [RUMS0792]. EPA's goal is to capitalize on improvements made by local users to the 1:100,000 scale RF3 data and, as the production of 1:24,000 scale hydrologic data continues, to provide a higher resolution reach file. The often complex issues associated with the update and enhancement of national spatial data sets, such as RF3, are currently being debated by the FGDC, which includes EPA representation, as part of the NSDI development process.

During the interim period, RF3 "alpha" data in its current un-validated form is available for use. Given the nature of the errors 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 will provide a much improved data product. In the mean time, access to the provisional RF3-alpha data, accompanying documentation, and technical support is provided through OW's 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. Existing documentation for RF3-alpha includes a technical reference and a list known problems with the current data.

Conclusion ("What does this all mean?")

RF3 is a valuable national spatial data resource. It provides a common foundation for improved water quality management at all levels of government. The recent high-level recognition that spatial data management issues are in fact of national concern and the resulting wide spread discussions on the NSDI have greatly increased opportunities for coordinated data sharing and make more substantial, far reaching solutions possible in the future. In recognition of this, EPA is committed to supporting RF3 and has pursued partnerships with other organizations to insure its completion and long term maintenance.

References

[CLIF1193]
Clifford, John; Dulaney, Richard A. and Olsen, Mark V., "Using the EPA RF3 Database to Facilitate Mandated Water Quality Reporting", USEPA, Office of Research and Development, November, 1993.
[DEWA0285]
Dewald, Thomas; Greenspun, Robert; Manning, Lee; Montalbano, Ann and Taylor, Phillip, Storet Reach File 1 Users Guide ("STORET.HELP.REACH.RETRIEVL"), USEPA, Office of Water, Office of Wetlands, Oceans, and Watersheds, February 11, 1985.
[HORN0594]
Horn, Robert C; McKay, Cindy and Hanson, Sue, "The History of the Reach File", 25th Environmental Systems Research Institute International User Conference, May 1994.
[RUMS0792]
River Reach File (RF3) Update and Quality Control Standards, Procedures and Management (Draft), USEPA, Office of Water, Office of Wetlands, Oceans, and Watersheds, July 31, 1992.

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