By Cathie Anderson | The Sacramento Bee
With more storms barreling toward Northern California, south Sacramento County communities near the Cosumnes and Mokelumne rivers are on edge for new flood evacuations this week.
Point Pleasant residents were ordered to evacuate on Sunday and Wilton residents were told to remain prepared to evacuate if they haven’t already even as reclamation district officials raced around the clock to shore up levee breaks ahead of the storm system expected to arrive Wednesday.
“We’re very concerned,” said Mark Hite, a trustee on the reclamation district that manages Cosumnes River levees in the area. “One of the somewhat benefits of this river. It comes up fast, but in the past, it also goes down fast. Hopefully, we can get a couple of days of dry weather and lose a couple of feet of flow.”
Levees are crucial along this 80-mile river because there’s no dam to slow the flow from headwaters in the El Dorado National Forest, said Jay Lund, vice-director of the Center for Watershed Sciences at the University of California, Davis. Consequently, he said, flash flooding is a common after warm storms like the one this past weekend that produced more rain than snow.
Lund said residents are not out of danger, despite the sunny skies on New Year’s Day. When a levee fails, he said, it can’t take the pummeling from the same flow of water that it had managed before the break.
Flood water from the New Year’s Eve storm already topped two south county levees, weakening them ahead of the the next round of rain. Lund said he’d want to be out of the area if he lived in the communities subject to the evacuation warnings and orders.
“If I was really close, I would hope that I had already evacuated. If I’m not flooded yet, I’d be worried,” Lund said. “One levee’s down, and it’s going to continue to go down. … I should evacuate either because the water is on its way to me or because maybe later on in the week — or next week even — that levee might still be failed.”
Evacuation the only option
Sacramento County warned residents in Point Pleasant, Glanville Track, and Franklin Pond to evacuate because floodwaters from the Cosumnes and Mokelumne rivers were moving southwest toward Interstate 5 and could reach those areas. Residents could be largely cut off from leaving by automobile.
The California Nevada River Forecast Center website shows that the Mokelumne River rose above its flood stage of 17 feet at Benson’s Ferry at 8 a.m. New Year’s Day, and the site projected the Mokelumne would reach a high of 21.2 in the wee hours of the morning Monday.
The Cosumnes River topped flood stage by 8 p.m. on New Year’s Eve. Evacuation is really the only option, said Lund and Kevin King, general manager of Reclamation District 1000, which manages levee in Natomas and points north.
“If it’s too late to get out, you’re going to be rescued by a helicopter or by a boat,” King said “People say, ‘Oh, we’ll just walk through it or whatever.’ This water is very cold is probably 55 to 60 degrees. … Here in the cold water that we have, you literally lose muscle control within three to five minutes, and your body just shuts down.”
If residents want to try and preserve family heirlooms or other items they can’t transport, Lund suggested they store them in the attic or at second floor level.
Cosumnes levee weakened in 2017 storms
In Wilton, reclamation district leaders began work to prepare for the storm on Wednesday, Hite said, placing loads of sandbags along the levees and arranging with farmers and ranchers to have their workers on call to put them in place as needed.
They also contracted with rock and gravel companies, he said, to truck boulders and other needed material to Wilton and to stand ready with the personnel to move it. And, it was.
The frustrating part for reclamation district officials, Hite said, is that they had to put off fortifying the levee in seven places damaged by flooding in 2017. The district didn’t have the money to do it, he said, and federal agencies turned them down when they sought financial help.
Perhaps the biggest challenge with protecting the Wilton are from the Cosumnes, Hite said, is that gravel and silt have collected in the river over the years and there’s just less space to hold the water.
“Under rare circumstances are we allowed to do any kind of work inside the riverbed, he said. “This river channel has gotten smaller over the years, as silt and sand have been transported downstream. So basically, we are now having some of these high water events and it’s been pushed through a straw that has gotten narrower. It would be nice if we could get away to do some internal dredging, removing excess sand and gravel from the riverbed.”
That situation won’t change by Wednesday when more rain comes to the region, but Hite and Lund said there are several factors working in Wilton’s favor. The next storm is expected to be colder, leaving more snow than rain. The precipitation isn’t expected to come down quite so fast. And, clear days between now and Wednesday will allow time for water levels in the Cosumnes to drop.
Rivers can rise fast in the Sacramento region, Sacramento County officials said, and residents should look out for evacuation warnings and make an evacuation plan, including which route they will take.