The National Weather Service has issued a flash flood warning as the levee along the north fork of the Mokelumne River is expected to fail.
Sacramento County officials are "strongly advising the residents of Tyler Island to evacuate. Tyler Island is expected to flood due to a compromised levee."
Officials say there's about 20-40 homes in that area.
"There was a question about whether or not the levee has failed," said Matt Robinson with the Department of Water Resources for Sacramento County. "It has not."
What has happened is a partial collapse of the levee and crews are using boulders to shore it up before it collapses even more. If that happens, they'll have to use sandbags to protect the area from the Delta.
Christopher Nudeck, a district engineer with the area, said that the Tyler Island area isn't known to overtop the way other areas with levee problems so far have.
"If this levee fails, we're gonna have 20 feet of water," said Nudeck. "Big event, if it goes."
Nudeck said that's what crews are trying to prevent. They'll be working overnight for at least a few days.
Sacramento Office of Emergency Services is also are advising Walnut Grove residents to take "precautionary measures due to flooding."
Walnut Grove residents are advised to take precautionary measures due to flooding at Tyler Island. https://t.co/3bcPbqOB7k. pic.twitter.com/cIezSIt7vG
— SacramentoOES (@SacramentoOES) February 13, 2017
Safe travel routes include Tyler Island Road south to Tyler Island Bridge Road and then to River Road either north or south, county officials said.
Locals can use Tyler Island/San Andrus Island roads north to Walnut Grove Rd. and then north or south to either River Rd. or West Walnut Grove Rd.
"The situation is dynamic," county officials said.
For more information check the Sacramento Office of Emergency Services website.