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Double-click to zoom in, and drag to pan. Hold down the shift key and drag to zoom to a particular region.

Zoom to Zip Code or City,State: Example: Pullman,WA

Start Over with New Area
Load a Project|Load a Project Archive

Show Legend
Measure Distance

Minimum Source Channel Length (m): Help!
Critical Source Area (ha):  Help!


  • November 19, 2012 - The rock content in the WEPP soil files based on SSURGO soils was too low for some soil layers. Adjustments were made to sum all rock volume sizes from SSURGO.
  • November 28, 2012 - The default climate generator has been set to version 5.3. The previous version, 4.3, can still be used by selecting it from Climate Processing Options section before WEPP is run.
  • November 18, 2013 - The help PDF document was updated.
  • November 21, 2013 - An Options tab was added to the main window. The latest WEPP model version 2012.8 was added as an option. Updated model run window.
  • November 26, 2013 - Fixed bug when area of interest spanned DEM tiles. Added NLCD 2006 layer as a reference. Uses single NLCD 2001 raster instead of tiles.

Getting around the map

Double-click to zoom in, and drag to pan. Hold down the shift key and drag to zoom to a particular region. Type in a city, state or a zip code to go to a specific area.

The list of GIS layers is available by clicking the + sign in the upper right of the map. To hide the list of layers click the - (minus) sign above the layers.

Delineating Channels

The first step is to zoom to an area of interest and click the Build Channel Network button.This will use the 30 meter DEM and the TOPAZ model to build a channel network for the area. The maximum size of the area that can be processed is about 0.2 degrees by 0.2 degreees.

Selecting an Outlet

After the channel network is complete click on a channel which will be the outlet of your watershed.

Delineating a Watershed

Click the Build Subcatchments button to find the watershed boundary based on the channel network and the outlet point selected. This step will also define the subcatchment areas that will be used as WEPP hillslope areas when making runs.

Review the Watershed

Click the Review Watershed button to finish getting the soil and landuse information for the watershed. This will also open a web page in a new window that shows the landuse and soil information for the watershed.

Make a WEPP Run

Finally, click this button to set the options for the WEPP simulation.


Online WEPP Interface Documentation

View the PDF Documentation of how to use the online WEPP interface. WEPP Online GIS (6.5mb PDF file) or the

SSURGO Data Availability

When the WEPP online GIS software delineates a watershed it requests soil data from the NRCS SSURGO database. Most of the United States is covered, this is the current map:
Web Soil Survey Coverage.

Where soil data is not available in a watershed a default soil is chosen.

How to download results to ArcGIS

View how to work with downloaded project data in ArcGIS. How to view downloaded project in ArcGIS

Browser Information

WEPP Model Version to use for simulations: Use model version selected

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