News Release

U.S. Department of the Interior
U.S. Geological Survey

Release: October 1, 2003

Contact:
Matt Ely
253-428-3600, x2622

Chris Konrad
253-428-3600, x2634

New Model Adds Irrigation to Simulate Streamflows in Methow Basin

[Note: The report can be viewed on the Web at http://pubs.water.usgs.gov/wri034246/ .]

A newly enhanced computer model of the Methow River Basin adds irrigation diversions to an existing model to simulate both current and natural streamflow in the basin, according to a report published today by the U.S. Geological Survey (USGS). The enhanced USGS model was developed in cooperation with Okanogan County and the Methow River Basin Planning Unit.

USGS scientists built on a previous watershed model by adding streamflow data from a new, more extensive network of stream gages in the basin. But the major enhancement of the model comes from adding irrigation applications, diversions, and returns to the simulation of streamflows.

"By accounting for irrigation water in the model, we can better estimate natural streamflows in the basin," said Matt Ely, USGS hydrologist. "The model now includes estimates of irrigation diversions and canal seepage, so when we shut off irrigation water in the model, we get an improved estimate of what natural flow conditions would have been."

The term "natural streamflow" means streamflow conditions that would exist if there was no irrigation in the basin. Resource managers need this information to make choices about how to allocate surface water for fish habitat, irrigation, and other uses. The Methow River Basin Planning Unit is developing a watershed plan in accordance with the state Watershed Management Act. In the basin, summer steelhead and spring Chinook salmon are endangered, and bull trout are listed as threatened.

The report, "Precipitation-Runoff Simulations of Current and Natural Streamflow Conditions in the Methow River Basin, Washington," by D. Matthew Ely, is published as U.S. Geological Survey Water-Resources Investigations Report 03-4246. The report can be viewed on the Web at http://pubs.water.usgs.gov/wri034246/. Copies can be purchased from the U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225-0286, telephone 303-202-4200.

The USGS serves the nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life. To receive USGS news releases, go to http://www.usgs.gov/newsroom/list_server.asp

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