Attributes for NHDPlus Catchments (Version 1.1): Level 3 Nutrient Ecoregions, 2002

This data set represents the area of each level 3 nutrient ecoregion in square meters,  compiled for 
every catchment of NHDPlus for the conterminous United States. The source data are from the 2002 
version of the U.S. Environmental Protection Agency's (USEPA) Aggregations of Level III Ecoregions 
for National Nutrient Assessment &amp; Management Strategy (USEPA, 2002).
		
The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates 
many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset 
(NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, 
naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments 
(drainage areas) produced using a drainage enforcement technique first widely used in New England, 
and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale 
NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The 
resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree 
with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey 
(USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method 
produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus 
dataset is organized by 18 Production Units that cover the conterminous United States.
		
The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's  Major River Basins (MRBs, 
Crawford and others, 2006).  MRB1, covering the New England and Mid-Atlantic River basins, contains 
NHDPlus Production Units 1 and 2.  MRB2, covering the South Atlantic-Gulf and Tennessee River basins, 
contains NHDPlus Production Units 3 and 6.  MRB3, covering the Great Lakes, Ohio, Upper Mississippi, 
and Souris-Red-Rainy River basins, contains NHDPlus Production Units 4, 5, 7 and 9.  MRB4, covering 
the Missouri River basins, contains NHDPlus Production Units 10-lower and 10-upper.  MRB5, covering 
the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf River basins, contains NHDPlus Production 
Units 8, 11 and 12.  MRB6, covering the Rio Grande, Colorado and Great Basin River basins, contains 
NHDPlus Production Units 13, 14, 15 and 16.  MRB7, covering the Pacific Northwest River basins, 
contains NHDPlus Production Unit 17.  MRB8, covering California River basins, contains NHDPlus 
Production Unit 18.

Tags: cali, california, catchment, cogb, conterminous-united-states, environment, geoscientificinformation, glmr, great-lakes-ohio-upper-mississippi-and-souris-red-rainy, inlandwaters, level-3-nutrient-ecoregions, lmtg, lower-mississippi-arkansas-white-red-and-texas-gulf, major-river-basin, missouri, mori, mrb, mrb1, mrb2, mrb3, mrb4, mrb5, mrb6, mrb7, mrb8, nawqa, nema, new-england-and-mid-atlantic, nhdplus, pacific-northwest, panw, rio-grande-colorado-and-great-basin, sagt, south-atlantic-gulf-and-tennessee, sparrow, usgs-ee0f0272-47fc-43a9-932e-6e1dbfb198f8
Organization: Department of the Interior