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NHD INDEXED LOCATIONS FOR SECTION 303(D) LISTED WATERS
Description:
River segments, lakes, and estuaries designated under Section 303(d) of the Clean Water Act. Each State will establish Total Maximum Daily Loads (TMDLs) for these waters. 303(d) Waterbodies are coded onto route.rch (Transport and Coastline Reach) feature of NHD to create Linear and Point Events. Point events are attached to a reach in NHD to represent a TMDL for many reasons: to represent an estuary, to represent a shellfish area (if state prefered to represent the TMDL in this manner) - refer to NOAA's shellfish areas for a more accurate representation (<http://state-of-coast.noaa.gov/bulletins/html/sgw_04/sgw.html>). Point events represent point source dischargers, or, if there is no reach in NHD, they are used to represent the TMDL. 303(d) Waterbodies are coded onto NHD Waterbody reaches (region.rch) to create Waterbody Shapefiles. In addition to NHD reach indexed data there may also be custom shapefiles (point, line, or polygon) that are not associated with NHD and are in an EPA standard format that is compatible with EPA's Reach Address Database. These custom shapefiles are used to represent locations of 303(d) waterbodies that are not represented well in NHD.