An intense riverine atmospheric storm continued to pressure strained levees in Monterey and Santa Cruz counties on Tuesday as officials considered emergency measures to prevent more catastrophic flooding from hitting the already inundated area. .
“The real issue today is manually breaching a section to relieve pressure,” said Zach Friend, a Santa Cruz County supervisor whose district includes Watsonville, which is now threatened by the swelling Pajaro River.
Just days ago, a breach in a levee along the river triggered massive flooding in the town of Pajaro, prompting dozens of water rescues and evacuation orders covering hundreds of residents. County and state officials have been working to stabilize the roughly 350-foot breach by laying down rocks and boulders to keep it from getting bigger, but there’s still no timeline for when. it will be repaired.
“When these systems come in and the system is already very wet, the flows don’t really go down for a while,” Monterey County water resources engineer Shaunna Murray said during a press briefing.
Adding to the challenge is that water flowing through a gap under Highway 1, between a levee and the freeway embankment, is “outside the river channel” and “erodes the levee from the side. from the floodplain rather than the side of the river,” said Mark Strudley, executive director of the Pajaro Regional Flood Management Agency.
Among the possible solutions is cutting Highway 1 to relieve pressure on the river, he said.
Major utilities, including a sewer and irrigation water pipe, cross the dyke and are threatened by erosion.
But its location makes it a tricky one – the only way to access the gap is through a small open area that stretches between the north and south lanes of Highway 1.
And because the tracks cross a shallow bridge, an excavator cannot be used to repair the erosion. Also, there would be no point in dropping rocks or sand through the opening between the tracks, as this could potentially damage the power lines.
“If water continues to erode through the levee such that it re-enters the river system…it could overwhelm the river system downstream of Highway 1,” where a water treatment plant is located Watsonville waste, Strudley said.
If the water overflows or seeps through the levee, “we risk destroying parts of the plant and may end up dumping untreated sewage into the floodplain, into the river and ultimately into Monterey Bay. “.
Officials have three options to deal with the situation, Strudley said.
“One thing you can do is open the dike downstream from that point – a bit downstream, but upstream from the treatment plant – to let the water flow back into the floodplain,” he said. he declares.
The second option” is actually to open Highway 1. Basically, cut through Highway 1 and the low point, which is south of the river, and let the water flow out of the plain floodable”.
The last option, he said, is to do nothing, which might be enough because the storm hasn’t hit as hard as expected. A decision is expected to be made Tuesday afternoon.
Times writer Hayley Smith contributed to this report.