Lopez Lake expected to spill excess water into Arroyo Grande Creek during forecasted storms

ARROYO GRANDE, Calif. – After adjusted rainfall predictions were issued by the National Weather Service, the County of San Luis Obispo's Office of Emergency Services expects Lopez Lake to spill earlier than previously stated.

Lopez Lake was constructed in 1969 as a water supply reservoir for drinking water and because of that, it has smaller-diameter pipes compared to a flood-control site.

Those skinny pipes mean the county can not release water as quickly in anticipation of incoming rain.

Storms during this year have raised the lake's water levels to near maximum capacity.

As rain begins to fall and the water levels rise, water will fall over the reservoir edge and into the spillway as designed.

The spillway leads excess water into Arroyo Grande Creek and that is where county officials indicate the excess water will have a notable impact on flood risk and debris flow as it has in January and February of this year.

County officials explain that Tally Ho Creek, itself subject to previous flooding this year, is not part of the main stem of Arroyo Grande Creek and is not expected to be affected by the spillway.

To prepare, the county's Public Works office will have road crews staged at areas upstream of Arroyo Grande to free culverts and bridges of obstruction and limit flooding.

Lopez Lake provides drinking water to residents of Arroyo Grande, Grover beach, Pismo Beach, Oceano, and Avila Beach and has spilled a total of 18 times since its construction in 1969. The last spill was in 1998.