Cosumnes communities on guard as new atmospheric river takes aim on Sacramento region
People along the Cosumnes River basin were preparing Wednesday for a powerful new wave of warm, late-winter storms and the prospect of snowmelt-fed flooding.
Elk Grove opened sandbag stations ahead of potential high water. To the east, in nearby Sloughhouse, monitors are watching the free-flowing river ahead of its expected rise late Friday.
Water districts along the Cosumnes were diverting river flows onto dormant vineyards to give its riverbanks breathing room ahead of the oncoming storm, while area emergency responders are applying lessons learned from January’s widespread flooding.
Eyes again are on MIchigan Bar on the river near Rancho Murieta, where forecasters predict water levels at 13.3 feet — a foot above flood stage — by 11 p.m. Friday. It’s the same spot where in January crews worked feverishly to staunch flows to save earthen downstream levees during the string of powerful storms that swamped Wilton and stranded motorists on a submerged Highway 99.
What happens at Michigan Bar is “a pretty good indication of what happens in the county. It happens there first,” Cosumnes Fire Department Operations Chief Dan Quiggle said Wednesday. Cosumnes Fire serves Elk Grove, Galt and the unincorporated south county where much of January’s fatal flooding occurred.
“We know three or four hours later, it will be really high at the Wilton Road bridge and it will be really high where the river crosses Highway 99,” Quiggle said.
That scenario played out with deadly consequences on New Year’s Eve night when the Cosumnes River overtook the highway. Two motorists were either swept away or trapped in their submerged vehicles on the highway at Dillard Road. Cosumnes fire crews rescued at least 50 others from their vehicles and logged 259 service calls from New Year’s Eve through New Year’s Day.
On Wednesday, Quiggle had a stern warning for motorists: “Do not drive on a flooded roadway,” he said, emphasizing each word. “Turn around and go back where you came from. One of the most significant impacts (of flooding) is people stranded on roadways.”
Memories of 1997 floods
For some, the looming storms recall the relentless Pineapple Express storms in 1997 that liquefied Sierra Nevada snowpack, leading to devastating flooding up and down the Sacramento Valley.
Rain from this storm will produce snowmelt runoff below 4,000 feet, forecasters said, but they emphasized that the 2023 version will not pack the same punch.
Though a warm rain-on-snow storm moves in during the day Thursday, “this is not a 1997 scenario,” Sacramento National Weather Service meteorologist Courtney Carpenter said at a morning briefing Wednesday. “We’re not expecting anything that warm or as wet, as we saw during kind of that six-day period in 1997.”
But forecasters are keeping watch on river spots across the region expected to rise above flood stage with this first round of storms, Carpenter said. including the Mokulumne River at Benson’s Ferry; the Tuolumne River farther into the San Joaquin Valley in Modesto; and the Cosumnes at Michigan Bar.
In Sloughhouse, east of Elk Grove, community water officials were mapping out plans and getting information to residents.
“We are sending out to all the members of our listserv information on sandbags, where to get help, how to follow conditions along the Cosumnes and when it will crest,” said Barbara Washburn of the Sloughhouse Resource Conservation District board.
Sloughhouse board members met Wednesday to discuss the heavy weather to come and its potential outcomes. “We’re trying to keep people apprised of what’s going on,” Washburn said. “Our main concern isn’t flooding of people’s homes. It’s the blocking of roadways, then people get stuck in their houses.”
Where to get sandbags
Elk Grove opened two sandbag stations Wednesday ahead of the storm at the City Corporation Yard, 10250 Iron Rock Way. Hours are 9 a.m. to 3 p.m. through Friday. A second location is open at 9260 Elk Grove Blvd., the site of the former Rite Aid drug store and future city library at Elk Grove and Waterman Road. The site will open Friday afternoon through Sunday.
Residents and businesses can get up to 10 sandbags at the self-serve sites. Bring proof of address and shovels.
In Wilton’s Omuchomne-Hartnell Water District, pumps have been diverting Cosumnes River water onto dormant vineyards since January under a State Water Board permit, while officials such as district manager Michael Wackman focus on the rain and Sierra runoff. Wackman is cautiously optimistic that the high water from this upcoming round of storms won’t match January’s flows.
“We’re going to get higher flows, but nothing like we got at the first of the year,” he said.
Meantime, Cosumnes crews are in what Quiggle called a “prepare and monitor mode.”
Now, a Cosumnes Community Services District member is working with emergency planners at the county’s emergency operations center. Quiggle and fellow fire operations chiefs from across the county will meet Friday morning to plot out mutual aid and receive new information on snowmelt and how much flooding that will mean downstream.
Another focus: More effective road closures in and around flooded areas to better alert motorists before they encounter trouble.
“We have learned quite a bit from our experience with the storms in January,” Quiggle said.
This story was originally published March 8, 2023 at 5:00 PM.
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