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Snowpack readings to remain accurate thanks to NASA
• $15 million snagged over five years
snow flyover
The Airborne Snow Observatory uses the Twin Otter aircraft to fly over the Sierra, collecting data on the snow melt.

Technology using radar to give an accurate analysis of the local water supply will continue with $15 million in federal funding for the Aerial Snowpack Observatory program. 

The ASO technology, which was developed by NASA, offers more precise measurements when measuring snow runoff, increasing the accuracy to within 96 to 99 percent compared to the 50 to 90 percent accuracy by conventional methods. Officials with Modesto and Turlock irrigation districts say more precise measurements allow water managers to make better forecasts on water allocations — using more water when it’s available and conserving water when it’s not.

When it was learned that NASA would be ending the program in December 2019, Josh Weimer of TID approached Rep, Josh Harder, D-Turlock, to explain the importance of continued funding. Recent snowpack readings using the ASO program were critical when determining the irrigation cap allotment for farmers this year, Weimer said, and also helps TID and MID determine how much water to release for fish flow purposes.

Harder was joined by leaders from Turlock Irrigation District and Modesto Irrigation District at a March 9 press conference to celebrate the securing of $15 million over the next five years for the program. Upon developing the new technology over six years ago, NASA selected the local Tuolumne River Watershed as one of the first watersheds in the world to test the ASO program. 

“This boils down to better measurement means better predictions, which means more water for folks across the Valley,” said Harder.

The Tuolumne River Watershed covers roughly 1,500 square miles and the antiquated method of measuring the snowpack saw crews monitor 17 different measurement points across the area. The ASO program uses laser pulses to measure the area first without snow, then with snow to determine how deep the snowpack is.

“This gives you a really good understanding since it’s not one of 17 points of measurement over the entire watershed, but a specific meter by meter model of how much snow is there,” Weimer said.

The latest snow survey showed statewide snowpack is just 61 percent of average, with only two wet months left in the water year.