One of the smaller ornaments on the Christmas tree of water projects in the recent federal spending bill was $3 million for a so-called “Snow Water Forecasting Program” within the Department of the Interior. The measure included another $15 million over the next five years. That may not have the flash and recognition of some of the other water projects, but could be huge for water management in the San Joaquin Valley. That’s because predicting runoff from Sierra watersheds that feed valley reservoirs from Yosemite down to Mount Whitney is difficult at best as it relies on widely scattered electronic snow sensors and infrequent physical surveys. Those methods are helpful, but have an accuracy range of 50 percent to 90 percent. The new forecasting money would pay for an airborne snow observatory (ASO) program to complement those conventional methods. For the past few years, valley water districts have been paying independently for ASO flights, which measure snow depth and water content using LIDAR (light detection and ranging). ASO along with conventional measurements boosts accuracy to between 96 percent and 99 percent. The information is invaluable in managing run off. But the flights are pricey, about $90,000 each. The state Department of Water Resources has participated in some flights, but to cover watersheds statewide would cost $15 million a year and legislative attempts to come up with that kind of money haven’t succeeded. Still, DWR has paid for some flights, such as the new “bare earth” ASO flight over the upper San Joaquin River watershed where the Creek Fire scorched more than 25 percent of the land. “The next flight is tentatively scheduled for the first of February,” said Jason Phillips, general manager of the Friant Water Authority, which depends on San Joaquin River water to supply nearly a million acres of farmland from Millerton Lake down to Arvin. He said the authority has about $300,000 budgeted this year for ASO flights, as needed and coordinates with other watersheds up the valley. The new federal funding will likely cover watersheds throughout the Bureau of Reclamation’s jurisdiction, not just California.