modeling support system developed by EPA’s OW/Office of Science and Technology (OST) 
(http://www.eDa.gov/ost/basinsA EPA 1998b), STORAGE and RETRIEVAL database 
(STORET), the Water Quality Standards Database, the TMDL tracking database, and Watershed 
Assessment Tracking and Environmental Results Systems (WATERS). In addition, 
incorporation of toxicity data into EPA’s STORET database will be coordinated with this effort. 
In siqDport of diagnostic efforts at the watershed scale, NHEERL will continue to collaborate with 
EPA’s Office of Environmental Information (OEI) and USGS Mapping Division (EROS Data 
Center) and Water Division in their work to produce a seamless nationwide geospatial database 
of watershed boundaries and associated hydrological derivatives [NED-H (now EDNA, 
Elevation Derivatives for Natural Applications), see 
http://edcntsl2.cr.usgs.gov/ned-h/index.html . Protocols for deriving watershed boundaries have 
been developed through an interagency task force coordinated by the Federal Geographic Data 
Committee (FGDC) and Advisory Committee on Water Information (ACWI), thus ensuring 
consistency across Federal agencies (see Federal Standards for Delineation of Hydrologic Unit 
Boundaries, 06/12/01 Draft; http://www.ftw.nrcs.usda.gov/huc data.html ). The USGS 8-digit 
hydrologic unit codes (HUCs) are being divided into finer units (10- and 12-digit HUCs) that are 
generally consistent with watershed boundaries for integrated drainages, and with boundaries for 
internal drainages to moderately-sized water bodies. The smallest of these units (12-digit HUCs) 
correspond to the scale of watersheds associated with wadeable streams. NHEERL is supporting 
development of GIS tools for automated watershed delineation using digital elevation models 
(DEMs), and hydrologic correction of existing DEMs to ensure consistency between synthetic 
streamlines and mapped hydrography. ThuSj attributes coded using the National Hydrography 
Database for streams (the successor to EPAs Reach 3 stream files) will be consistent with the 
Nationwide Watershed Boundary Dataset under development. Regional case studies (project 3) 
will provide an opportunity to use the Nationwide Watershed Boundary Database under 
development to demonstrate its usefulness in watershed-scale monitoring designs, assessments, 
diagnosis, and management across an integrated series of watershed scales. 
Second, a nonpoint-stressor analog to the Ecological Toxicity Database (ECOTOX) 
(http://www.epa.gov/ecotox/. Hunter et al. 1990) will be developed that will contain information 
on stressor-response relationships for nontoxics, stratified by an appropriate classification 
framework (project 2). ECOTOX is a source for locating single chemical toxicity data for 
aquatic life, terrestrial plants and wildlife. ECOTOX integrates three toxicology effects 
databases: AQUIRE, terrestrial plants (PHYTOTOX), and terrestrial wildlife (TERRETOX). 
Toxicity test results and related testing information for any individual chemical from laboratory 
and field aquatic toxicity tests are extracted from the literature and recorded. Lethal, sublethal, 
and bioconcentration effects are recorded for freshwater and marine organisms, along with 
pertinent information on laboratory or field test conditions. The current database structure could 
be adapted readily to store information on stressor-response relationships for non-toxics. These 
data would ultimately support the development of regional and/or national criteria for nutrients 
and suspended and bedded sediments. 
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