Timely Rain Bolsters State Water Supply
Boise–A cool, wet spring combined with timely rain has turned the 2009 runoff into a 'moderate water supply year' according to the June Water Supply Outlook Report released by the Idaho Natural Resources Conservation Service.
“Average precipitation for the water year is good for the forests and rangelands, but the timing and intensity of spring rain can affect snowmelt runoff and irrigation demand for Idaho's water users,” said Ron Abramovich, NRCS water supply specialist. “Just like water on the Wicked Witch of the West, spring rain, and hot temperatures, can cause untimely melting of the snow.”
June 1 snow levels are near average in the Clearwater basin and the snow is melted in the southern Idaho basins, except in the highest elevations.
Reservoirs across Idaho are filling up except a few in southern and central Idaho. This could make irrigation water supplies tight for users in these basins. Depending on the summer's irrigation demand, better carryover reservoir storage for next year is also favoring basins that had better carryover from last year; these include Dworshak, Payette, Boise and Upper Snake reservoirs.
To provide guidance to water managers and river runners, there are a number of graphs on the Idaho NRCS Peak Streamflow Resources page: http://www.id.nrcs.usda.gov/snow/watersupply/peakflow.html.
Projections are made periodically after the snowmelt peaks have occurred and streams are receding. These graphs are manually updated once a week or more during the runoff season and less often in the summer months.
For more information about snowpack, precipitation, runoff and water supplies for specific basins, please view the complete June 2009 Water Supply Outlook Report online at www.id.nrcs.usda.gov/snow and click on the ‘Water Supply’ link.