Water will be more than abundant this year

All of Idaho will have adequate water supply this year and too much in some basins. Latest water supply reports are encouraging water managers to plan for higher volumes of streamflows, which could be 10 to 30 percent higher than earlier forecasts. The Natural Resources Conservation Service (NRCS) reported there would be abundant water supplies across the state. March storms are expected to bring several feet of snow into the western and northern parts of the state. Water supply shortages are not expected. NRCS said that because there is plenty of soil moisture already in the ground, there could be reduced demand for irrigation water early in the season. That means additional water may be available to use or release. “During February, the mountains of Idaho received 150% to 500% of normal monthly precipitation,” said Daniel Tappa, hydrologist with the Idaho Natural Resources Conservation Service. Streamflow forecasts are moving toward record high territory. The lowest forecasts in the Upper Snake are in the Henry’s Fork and Falls River basins at 125 to 133 percent of average. The Teton River is forecast at 150 percent and the Snake River at Heise is forecast at 173 percent of average. Willow Creek at Ririe Reservoir is forecast at 236 percent of average. The Portneuf River is expected to run at 166 percent of average for the period of March through July. According to the latest NRCS data, the lowest snowpack in the upper Snake River drainage is in the Henry’s Fork, Falls River, and Teton Rivers at 125 percent of median. To the south and east, snowpack increases to 202 percent in the Hoback basin in Wyoming. Palisades Reservoir snowpack is 159 percent of average with several measuring sites at or near record highs. Precipitation amounts in the first five months of the water year, which began October 1, 2016, are 91 percent of average year totals along the Snake basin above Palisades Reservoir. NRCS said the area is just a storm or two away from exceeding annual precipitation amounts. Overall snowpack is 152 percent of normal above American Falls Reservoir. The Willow, Blackfoot, and Portneuf basins are 145 to 160 percent of median. Bear River snowpack is 166 percent of median, which is the third highest since 1975. The full March water supply outlook report is available here.