Southern Central Valley Counties Brace for Flooding as Heat Wave Melts Sierra Snowpack

Standing before a tractor peeking out of a temporary inland sea, Gov. Gavin Newsom said that if you don’t believe in climate change, visit California.

“People here are quite literally just a stone’s throw away in houses that will likely be underwater in a matter of months,” Newsom said, of homes protected by a threatened levee outside the Kings County town of Corcoran, home to 22,000 people and a prison complex.

Central Valley counties — Kern, Kings, Fresno and Tulare — are on high alert as the heat melts the southern Sierra’s snowpack, which is at 324% of normal for this date since the state began conducting snow measurements in 1910. The levee protecting Corcoran is in question as the flows push against the structure.

“For the governor to be here today lowers the anxiety level in Corcoran,” said Richard Valle, who was born in Corcoran and now represents the town on the Kings County Board of Supervisors.

Tulare County Supervisor Eddie Valero said that in the past few months, in his county, atmospheric river flooding breached canals more than 50 times, swamped more than 640 homes, destroyed 37 houses and restored Tulare Lake — a former inland lake historically dried up and replaced by farmland and cities.

“People are tired, homes are gutted, lands aren’t harvestable and the livelihoods of many are at stake,” Valero said.

Flood risk is expected for the next four months.

“We are now into the next phase of the winter-of-2023 storm event and flood emergency, and that is planning for a historic snowmelt season,” said Karla Nemeth, director of the California Department of Water Resources.

A nearly statewide heat wave is expected to bring 90-degree temperatures to inland California, which will begin to melt the massive snowpack — record-breaking in the southern Sierra Nevada — and flow into rivers and reservoirs.

The flows have the potential to flood mountain and valley communities; the bounds of Tulare Lake will likely only grow more prominent. In response, state and local governments are taking action to build up levees where possible, modeling how runoff will flow into the valley and taking every chance to protect people in the region.

Michael Anderson, the state’s climatologist, said one of the big reasons the big melt will likely occur is because temperatures at night are supposed to stay warm.

“Towards the end of the week, we’re gonna see things warm up, and warmer outcomes mean more snowmelt,” he said.

But just how much snow will melt is determined by the sun’s angle, the length of the day and how much radiation makes it into the snowpack, Anderson said.

“This week is just going to get progressively worse and then maybe relent a bit the following week,” said UCLA climate scientist Daniel Swain. “The problem is there’s nowhere else for this water to go, and the Tulare Lake basin is just going to fill up like a bathtub.”

The state is running models to see what the impact of snowmelt might be like in places like the Tulare Lake basin, said Brian Ferguson, deputy director of crisis communications and media relations for the state Office of Emergency Services (Cal OES), at a media briefing Monday.

“There’s water jujitsu happening,” he said. “Flowing with the water to put it where it needs to be, but also understanding what are the emergency protective measures we as a state along with our local and federal counterparts can do to help protect these communities.”

Ferguson said as the rate of flood risk speeds up, the state is prioritizing public safety. It is approaching the crisis from a regional perspective since four counties have the potential to flood.

“We cannot dig our way out of this,” he said. “We just need to be smart about the steps we can take holistically to protect as many people as possible.”

The agency is also paying close attention to public infrastructure in the path of floodwaters — things like sewers, hospitals, nursing homes and prisons.

“We’re going to have a challenging few weeks to come, but one of the things that we continue to be impressed with is the ability of Californians to come together during these challenging times,” he said.

A flooding resource center is now open in the community of Farmersville, and mobile units will be dispatched across the region.