The National Network of Reference Watersheds

NNRW Core Watersheds

The National Network of Reference Watersheds has defined a set of "Core" reference watersheds. NNRW Core watersheds meet the following criteria: Low hydrologic disturbance (dams, water withdrawal, pollutant discharge); 0% Row Crops; < 5% Pasture; 0% High Impact Development; 0% Medium Impact Development; < 10% Total Development (High + Medium + Low); Natural vegetation + Barren Land > 75%. Core reference watersheds also have stream discharge data available. The NNRW core reference watersheds are defined using land use characteristics calculated from the National Land Cover and Land Use dataset from 2006.

NNRW Core watersheds can be used is to define reference or "background" conditions across the Nation and to measure changes in baseline conditions through time or to compare to disturbed areas. To search for Core Watersheds, first define the area(s) of interest and then choose the water quality parameters of interest.

State(s): InformationHold Ctrl to select multiple states at once.

Counties will be loaded here according to states selected

Level II Ecoregions: InformationEPA Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources
Water Resources Regions: Information21 geographic areas that contain either the drainage area of a major river or the combined drainage areas of a series of rivers
Agency(s)/Partner(s): Informationthe Federal, State, tribal, interstate, academic, local and private sector organization responsible for the site, this option can be left blank while still selecting a program/ network
Program(s)/Network(s): Informationselect sites based on programs or networks to which they belong; sites may belong to multiple programs or networks
Characteristic Group: InformationThese water quality characteristic groups are pre-set by the water quality portal
Time Period: Informationleave time period blank to retrieve entire period of record
Start Date:  /  /
End Date:  /  /
Watersheds within  kilometers of an NADP station
Watershed Area (range)InformationInput the range in watershed areas or leave blank to include all watershed sizes.  to   kilometers2
Elevation at outlet (range)InformationThis is the elevation at the watershed outlet. Leave blank to include watersheds at all elevations.  to   meters  


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Site Last Modified: 27 February 2018
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