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EPA Reach File References
The U.S. Environmental Protection Agency's (USEPA) Reach Files
are a series of national hydrologic databases that uniquely identify
and interconnect the stream segments or "reaches" that comprise the
Country's surface water drainage system. The three versions of the
Reach File that currently exist, known as RF1, RF2, and RF3-Alpha
respectively, were created from increasingly detailed sets of digital
hydrography data produced by the U.S. Geological Survey. RF1, at a
scale of 1:500,000, is still utilized
while RF2 and RF3, at a scale of 1:100,000, have been superseded
by the National Hydrography Dataset (NHD).
The USEPA enhanced these hydrography
datasets by assigning a unique reach code to each stream segment,
determining the upstream/downstream relationships of each reach, and,
when possible, identifying the stream name for each reach. A variety of
other reach-related attributes that support mapping and spatial
analysis applications, such as the stream level attribute, are also
available.
Click on the graphic below to explore the various Reach
File references.
