The Director’s Report for the Oregon Water Resources Commission January Meeting breaks down water conditions in the State:
“Current Water Conditions: The surface water supply index (SWSI) is a numerical index computed for the 14 major water basins in Oregon. The index ranges from + 4.0 indicating extremely wet conditions to – 4.0 indicting extremely dry conditions. An index of 0 would indicate normal conditions. The index is computed monthly and generally considers snowpack, rainfall, irrigation reservoir content and average monthly streamflow. On December 1, 2011 the indices in the 14 basins ranged from -1.5 in the Klamath Basin to +1.6 in the Deschutes Basin. According to the SWSI, water conditions in Oregon are generally below normal and trending downward.
On January 9, 2012 snowpack conditions range from a high of 55 percent of normal in the Grande Ronde, Powder, Burnt and Imnaha Basin Basins to a low of 19 percent of normal in the Owyhee Basin. Generally, snowpack is currently well below normal after 3.5 months into the water year.
We normally experience the bulk of our snowpack accumulation in December, January and
February. Total precipitation for the water year ranges from a high of 69 percent of normal in the
Grande Ronde, Powder, Burnt and Imnaha Basins to a low of 44 percent of normal in the Lake
County/Goose Lake Basin.
Storage carryover in the major irrigation reservoirs puts them at near normal capacity.
The northwest is still under the influence of La Niña conditions and continues to be forecasted for below normal temperatures and above normal precipitation over the winter period. However, these conditions have not been consistent with the moving three month forecast. Storms have been consistently pushed to the north, leaving the state with below normal water conditions.”