For those trained to study the Earth’s surface, looking at the pristine snowpack atop the Sierra Nevada is like looking into the future. Most of the snow blanketing the Sierra peaks today eventually melts and flows downstream, filling rivers and lakes and providing water to millions of California residents, farms and recreation sites.

Each year, Southern California Edison conducts several snow surveys where hydrographers scale the Sierra to measure snow density at multiple points along the more than 400-mile-long mountain range. Their job is to anticipate how much snowmelt will flow when it gets warmer. Capturing an accurate forecast is critical to determining a significant portion of the state’s water supply and as a key indicator of the hydroelectric power that can be safely generated from the runoff.

“These surveys help us stay in line with dam safety guidelines for managing the reservoirs,” said Jay Kimbler, generation senior manager of SCE’s western operations. “We start making adjustments to reservoir levels and generation now in order to safely accommodate the forecast runoff.”

The team at SCE that manages power generation closely monitors survey results to forecast the amount of water that will move through its Big Creek Hydroelectric Project on the west side of the Sierra and its Bishop Creek and Mono Basin systems on the east. Hydroelectric systems are designed to generate renewable energy from whatever water supply is available and use a network of lakes and reservoirs to store the water so it may be used to power customers during periods of peak demand.

To date, the statewide snowpack is measuring at 101% of average — a welcome return to normalcy following a record winter that pushed reservoirs to capacity.

“A normal year means we will have plenty of water to generate during the high demand times of the year, which eases the pressure of dam safety concerns,” said Kimbler. “We always monitor lake levels closely, but with an overabundance of water, we have to forecast and manage water levels more precisely for a longer period of time to make sure we don’t approach the use of spillways or overfill a reservoir.”

While hydroelectric systems are not designed to hold back runoff or control the total volume of water moving downstream, they do manage several priorities. These systems generate electricity, protect natural and cultural resources, help deliver water to farmers, businesses and water districts, and support local recreation. A strong water year, like current data is forecasting, is a good sign for water rights allocations and a summer of healthy recreational waters.

A final snow survey traditionally occurs at the beginning of April, when nearly all the snow of the season has accumulated and begins the transformation from winter snowpack to spring runoff.

For more information on clean power, visit edison.com/cleanenergy.