With more storms on the way as of Feb. 14, county officials were continuing to keep a close eye on the Arroyo Grande Creek levee as early February storms pushed Lopez Lake over its capacity.
SLO County Public Works Engineer David Spiegel told New Times that the dam began spilling on Feb. 7 around 10 p.m., making it the second time in 25 years that Lopez has overflowed. The first time was last March. On Feb. 14, the lake was more than 100 percent full at 49,388 acre-feet.
“It’s still spilling at a rate of 32.6 cubic feet per second, or 21 million gallons, per day,” he said on Feb. 13. “It has not caused any damage at this point or impacted any residential areas.”
SLO County Water Resources Engineer Brandon Zuniga told New Times that comparing 21 million gallons a day to a normal household’s use of 100 gallons is shocking, but it’s far less than previous spills.
“Like many floods management engineers, I like to convert it to cubic feet per second, and when you do that, it’s a pretty small rate compared to what we saw last year during the winter storms,” he said. “Right now, it’s about 3 cubic feet when last year it was hundreds per second.”
Zuniga said thanks to a break in stormy weather, the dam’s overflow isn’t a concern for the creek levee right now, but as the National Weather Service forecasts future rain, it’s something he’s watching.
According to the National Weather Service website, rain was expected to begin Feb. 17 and last until Feb. 20, and Zuniga said crews were in the process of removing debris out of the creek caused by strong winds in early February to prepare for possible flooding in the next storms.
“We kind of anticipate that Lopez will be contributing anywhere between 20 and 40 percent of the flows down at the levee portion of the creek, so that means we’ll definitely be on high alert this upcoming weekend,” he said. “We want to make sure that we’re monitoring the creek and making sure any issues that arise are taken care of.”
While the county anticipates flooding, Zuniga said it most likely won’t be at the same level as last year.
“Right now, based on the projections, it looks like we’ll be getting about an inch of rain and with the size of the watershed, it should be able to move new flows pretty quickly,” he said.
Zuniga said storm predictions are often subject to change, including rain intensity and duration, so keeping an eye on how the storm moves through the county is the best way to determine possible flooding.
“We could get an inch over 24 hours, in which the creek can definitely handle that amount of water, but if it’s an inch over a small period of time, such as three or four hours, that looks different,” he said. “I think we should be OK, but that’s me basing it off of what the National Weather Service is saying right now.” Δ
This article appears in Feb 15-25, 2024.