A transformation is taking place in the Sierra Nevada; as the snow from this season's heavy storms is melting, it is flowing down the mountain range and turning into one of California’s largest freshwater resources. While the water supply is critical to mitigating drought conditions, the increased flows mean more risks for people enjoying summer recreation as they wade into lakes and reservoirs.

“Southern California Edison oversees the safe operation of an array of dams and reservoirs, striving to serve Californians by providing clean, reliable electricity and recreational opportunities,” said Nima Ehsani, Water Resources and Hydroclimatology advisor with SCE’s Generation department. “During the snowmelt season, hot temperatures may induce a rapid increase in stream flows that can lead to potentially life-threatening situations.”

SCE manages hydroelectric projects on the eastern and western slopes of the Sierra, leveraging the natural watersheds to generate electricity and provide safe access points to the lakes and reservoirs that hold the water before it reaches its final downstream destination. This water year, those reservoirs are working at full capacity. The peak snowpack in the Southern Sierra was recorded at 301% of average, and the total stream flow volume is projected to be 250% of average for the Big Creek Hydroelectric Project and also significantly above average for the Bishop Creek and Mono Basin systems.

While SCE’s system is not designed to hold back all the runoff, and therefore cannot control the total volume expected during the melt, the company manages the water as it passes through its hydroelectric systems. SCE’s engineers and scientists are monitoring conditions closely to ensure the systems work as they should, produce the clean power we need and help preserve public safety.

“Though we are anticipating increased water flows into and out of our reservoirs during the peak runoff from June to August, we do not believe these flows will pose a significant dam safety risk,” said Matthew Paruolo, SCE’s Eastern Sierra Government Relations manager. “We’re proactively working with local governments, federal and state agencies to reduce the potential impacts on our mountain communities.”

The company’s hydroelectric system operators balance many priorities including water management for storage, electricity generation and agriculture, as well as dam safety.

SCE reminds boaters, swimmers and everyone who will be on, near or in the water that they bear the responsibility for their own safety and the safety of others around them. Being careful and keeping a close eye on conditions can help each person have a safe and enjoyable experience during what’s projected to be a lengthier recreation season due to the high water flows.

“We will see extended flows from the reservoirs and from the surrounding water sheds, into the streams below, and these streams can be very hazardous with high, fast-moving flows,” said Jay Kimbler, senior manager of SCE’s Western Operations. “Water temperature may also be much colder than normal and expose swimmers to ‘cold shock,’ which can cause changes in breathing, blood pressure and heart rate. These conditions create a greater risk of drowning, that’s why it’s important to always wear a life jacket.”

Click here for more information about National Dam Safety Awareness Day, May 31.