Over 2 million acres of southern Idaho farm and ranch lands get their irrigation water from snowmelt and reservoir storage. In the past, these surface-water irrigators have relied on basin-wide estimates to project their upcoming season's water supplies. Now, University of Idaho agricultural engineer Brad King, senior scientific aide Ralph Oborn and economist Chris McIntosh have developed a statistical approach that projects the probability and severity of water shortages down to the irrigation-district level in major potato-producing areas.

 

Projections for 2005, which incorporate each district's water-rights priority dates along with each basin's hydrology, are now available on the Web at http://extension.ag.uidaho.edu/droughtpredict. January predictions will be updated for February, March and April.

While basin-wide water supply estimates are available from federal and state water resources agencies, an individual producer's water supply "can be vastly different due to water-right priority dates, which actually determine how water is distributed among users," says King. "In order for producers to manage risk during drought conditions, they need to know the interaction between water rights and total water supply."

Also on the Web site, potato growers facing water shortages can find information developed by Steve Love, Jeff Stark and other UI potato scientists that will help them make water-stretching changes in their management and select less water-demanding varieties. They can click on UI field-trial results describing potato yields per inch of irrigation, evaluating different potato varieties for drought tolerance and comparing reduced-irrigation methods. Another section presents ideas for mitigating the impacts of reduced-water years. A section on economics, emphasizing drought-related risk management, is under development.

The Web site is a joint project of the UI Center for Potato Research and Education and the USDA Risk Management Agency. Stark, the project's leader, says that the water supply estimates will be available to growers every year between January and April.