WATSONVILLE, Calif. >> Crews rushed to repair a levee break on a storm-swollen river in California’s central coast before yet another atmospheric river arrives Monday night, further walloping the state’s swamped farmland and agricultural communities.

The Pajaro River’s first levee rupture grew to at least 400 feet (120 meters) since it failed late Friday, officials said. More than 8,500 people were forced to evacuate, and around 50 people had to be rescued as the water rose that night.

A second breach opened up another 100 feet (30.48 meters) of the levee closer to the Pacific coast, providing a “relief valve” for the floodwaters to recede near the mouth of the river, officials said Monday during a news conference.

Built in the late 1940s to provide flood protection, the levee has been a known risk for decades and had several breaches in the 1990s. Emergency repairs to a section of the berm were undertaken in January. A $400 million rebuild is set to begin in the next few years.

Forecasters warned of more flooding, wind damage and potential power outages from a new atmospheric river expected to arrive Monday night in northern and central parts of the state and move south over several days. California has been pummeled this winter by 10 atmospheric rivers, which are long, narrow plumes of moisture that turn into rain and snow when they make landfall.

Water from the upcoming storm will likely go over the Pajaro River’s levee — but crews were working to make sure the rupture doesn’t get any larger, said Shaunna Murray of the Monterey County Water Resources Agency. Over the weekend, crews had to build access roads to get to the site of the breach, and bring in rocks and boulders to plug the gap.

The river separates Santa Cruz and Monterey counties, about 70 miles (110 kilometers) south of San Francisco.

Monterey County officials also warned that the Salinas River could cause significant flooding of roadways and agricultural land, cutting off the Monterey Peninsula from the rest of the county. The city of Monterey and other communities are located on the peninsula.

Undersheriff Keith Boyd said first responders have rescued about 170 people who were stranded within the county’s evacuation areas since Friday, including a woman and her baby who got stuck trying to drive through high waters.

The undersheriff said 20 to 40 people remained trapped Monday near the Salinas River because the roads were impassible for rescuers.

Authorities had not received reports of any deaths or missing persons related to the storm as of Monday afternoon.

Winery and agricultural experts from the region said they are concerned about the storms’ impact on crops — both ones in the ground that are currently submerged, and ones that should be planted for the upcoming growing season.

Gov. Gavin Newsom on Sunday declared a state of emergency in six more counties after earlier making declarations for 34 counties.

Last week’s atmospheric river carried warm subtropical moisture that caused melting at lower elevations of California’s Sierra Nevada snowpack, adding to runoff that has swelled rivers and streams.

But the snowpack is so deep and cold that it mostly absorbed the rain, resulting in an even greater snowpack in the southern and central Sierra, said Daniel Swain, a climate scientist at the University of California, Los Angeles.

California Department of Water Resources online data showed Monday that the water content of the Sierra snowpack was 207% of the April 1 average, when it is normally at its peak. In the southern Sierra it was 248% of the average.