Removing a berm for future flood protection

If you’ve driven north on U.S. 101 around Coyote Valley recently, you may have noticed that a big, gray berm that was put in last year is now gone.

The Santa Clara Valley Water District put in the berm as an emergency measure to stanch flooding on the freeway from a breached canal. So why take it out?

We have removed it and transferred the material to the head of the out-of-service canal, closer to Anderson Dam, to raise the crossing there. This will help keep water from overtopping the nearby Coyote Creek banks into the canal like it did in February 2017, when our area was pummeled by back-to-back atmospheric rivers that dumped an unprecedented amount of rain. The water from the creek was too much for the canal to handle, and it flooded the freeway.

Through a series of intentional breaches in the canal and the plugging of the canal just downstream of those breaches, we are ensuring that any water that enters the canal will divert back into the creek.

This work should ensure that any water that enters the canal is surface runoff from the nearby hillsides, which it is equipped to handle.

The original berm work was completed on Feb. 22, 2017, as water district crews worked around the clock to deal with the flooding on U.S. 101. During the storms that caused extensive flooding in San Jose last year, flows in Coyote Creek increased and water began to flow into Coyote Canal and then onto U.S. 101 about a quarter mile north of Cochrane Road, flooding the freeway for most of the day.

Water district crews finished the temporary repairs at 1 a.m. after breaching the canal upstream so that water would be diverted back to Coyote Creek, rather than over the freeway. Crews also created a temporary dam at the point the canal was first breached to prevent water from flowing further down the canal. Approximately 2,000 tons of material was trucked to the site and used for the repair.

The Santa Clara County Water Conservation District, the precursor agency of Santa Clara Valley Water District, built Coyote Canal in the early 20th century to convey water from Coyote Creek for groundwater recharge. It runs along the hillside east of U.S. 101 toward groundwater recharge ponds near Metcalf Road. This canal is not currently used since the water district constructed a pipeline to convey water across the valley.

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