Swollen by days of heavy rain, the Cosumnes River in south Sacramento County is projected to overflow its banks early Wednesday morning, prompting officials to call for voluntary evacuations Tuesday of low-lying areas in rural Wilton.
The river is expected to top flood stage before midnight, and crest about 2 a.m. Wednesday, reaching its highest levels since the floods of 1997, according to the National Weather Service.
Water may begin topping a small agricultural levee on the river’s south bank as early as 11 p.m., county emergency services officials said. Flood stage is reached on the Cosumnes River when water depth exceeds 12 feet. Wednesday early morning’s peak is expected to hit 14.1 feet at Michigan Bar.
Local fire and county emergency officials were telling some of the area’s 5,000 residents to pack up Tuesday during daylight hours in case they needed to leave their homes later.
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“If you are in a flood-prone area, or close to the river, now is the time during daylight to get out, so we don’t have to evacuate in the night,” Wilton Fire Protection District spokesman Casey Robinson said. “Anybody in the low-lying area along the river would be susceptible.”
A computer analysis suggests about 1,000 people live in the area that might be affected by tonight’s flooding, but some or many of their homes may be built on berms or otherwise on high-enough land to avoid flooding, Sacramento County emergency services official Mary Jo Flynn said.
Safety officials planned to open an evacuation center at the Elk Grove regional park pavilion at 7 p.m. Tuesday and encouraged concerned residents to take advantage of it.
It’s better to leave home during daylight hours than to risk driving after dark on what may be flooded roads when water is harder to see, Flynn said.
While some residents planned to evacuate, many in Wilton said they will stick it out.
Bill and Lill Nichols, who run a horse farm near the river on the south side, said they do not plan to leave.“We have no concerns,” Lill Nichols said. “We have animals and can’t evacuate anyway.”
Robinson of the Wilton fire district said safety officials with the county and several fire districts are poised to help where needed. If there are any official evacuations, those will be made through Sacramento-alert.org for affected residents.
“The wildcard is a levee break,” he said. “That can happen anytime.”
Earlier this week, the Cosumnes River levee suffered a boil – under-levee seepage from the river – near Wilton Road. The boil was sandbagged and stabilized Monday. Crews were out Tuesday dumping gravel on the top of the road in hopes of shoring up the weakened levee as heavy trucks drove on top of it to get to the boil for repairs.
Local officials were also planning to dump large concrete hunks along the shores of the bridge crossing the Cosumnes River.
The last major flood in the Wilton area occurred in 1997 when the levees broke in 17 places, and the river flooded 300 homes. The Cosumnes River hit depths of 18.5 feet back then, and Sacramento Sheriff's deputies flew over the area with helicopters, urging the evacuation of about 2,500 residents.
If recent history is a guide, the latest storm will cause some flooding around the Cosumnes River in low-lying farm and ranch areas, but not be nearly as disastrous as the 1997 storm.
The area’s reclamation district has strengthened the levee system in recent years.
In March 2006, the Cosumnes River peaked at 13.4 feet. During that storm, the river broke through private levees in two locations near Twin Cities Road, flooding several square miles of farmland and forcing the road to close for about a day.
A few months earlier, in December 2005, the Cosumnes River peaked at 13.7 feet, causing the river to top a levee and closing parts of Dillard Road.