Pacific Gas and Electric : PG&E team responds to “slow moving disaster” of Tulare Lake flooding

By Denny Boyles

After what felt like a nonstop conveyor belt of winter storms that brought downpours of rain, strong winds and thousands of power outages, most of California is enjoying the return of blue skies.

In the Central Valley communities of Corcoran and Alpaugh, the blue sky is reflected in a mirror no one wants to see - a slowly growing flood as the once-dormant Tulare Lake refills from rivers swelled by a massive snowpack run-off in only the first stages of a spring melt.

The growing flood threatens three PG&E Substations, miles of distribution and transmission lines and dozens of pieces of ground mounted equipment such as transformers.

Local PG&E crews began responding to reports of flooding on March 28. On April 13 PG&E activated Incident Management Team 2 to coordinate efforts to protect infrastructure and keep power on for as many customers as possible,. Team 2 Incident Commander Vince Magri said the first goal was to ensure safety and assess the extent of the risks.

"Our first surveys from the ground and air showed what we suspected - waters are already impacting our facilities, and the worst is yet to come. It's a slow-moving disaster, the water is not coming quickly but we all know it is coming," Magri said.

To manage the mitigation, Magri's team have assembled a diverse and unique mix of personnel and equipment. Lineman patrol above the lake in helicopter and on the surface in swamp-style air boats. Dive crews disconnect 5000-pound transformers that are already underwater so that a Chinook helicopter can lift them and carry them to nearby landing sites.

One of the biggest concerns is potential flooding to substations in the towns of Corcoran and Alpaugh, and the nearby community of Angiola. Corcoran has 20,000 residents and is home to state prisons with more than 8,000 inmates.

Adam Kincade, South Valley Substation Maintenance and Construction Superintendent, is overseeing construction of flood mitigation walls around the substations. At Angiola, the walls will be 16-feet high.

"We have to protect against not the just the predicted height of the flood water, but also wind-driven waves that could be more than a foot high," Kincade said.

Wave action is a concern for Tulare Lake, which was once the largest freshwater body west of the Mississippi River and could grow larger than Lake Tahoe this year.

The lake is fed by multiple rivers carrying melted snow from the southern Sierra Nevada. Those flows that helped Tulare Lake cover more than 690 square miles of land at its largest.

In the last 40 years the lake has only reemerged twice, in 1983 and 1997. In 1983, the snow recorded its highest snowpack ever and it took two years for the lake to fully recede. This year's snowpack is one of the largest ever with the southern area, which feeds Tulare Lake, at more than 300 percent of average.

"As we plan, we have to consider that some of these communities may be impacted for years. It's unlike any storm response most of us have seen during our careers. The blue skies don't mean the problems are over," Vince said.