Antelope Valley’s neighbors to the east now have something to worry about.
According to an article in USA Today, some Californians have serious concerns over water. Officials have worries that the Mojave River Dam could breach in an extreme weather event.
Flood waters could threaten Hesperia, Apple Valley, Victorville and Barstow.
Jorge L. Ortiz wrote that “A decision by the U.S. Army Corps of Engineers about a danger most Californians didn’t even know existed serves as reminder that everyone is at the mercy of Mother Nature, and preventive measures can go a long way toward sparing life and property.”
“What did the U.S. Army Corps do?
“It switched the Dam Safety Action Classification of the Mojave River Dam from low to high urgency of action, meaning steps must be taken to safeguard communities close to the river.”
The risk assessment determined that, in an extreme weather event, water could flow over the nearly 50-year-old dam and it could breach, endangering 16,000 residents downstream and property valued at $1.5 billion. Floodwaters could reach as far as 150 miles away.
“What measures must be taken?” the writer asked.
He wrote that, “The most immediate is raising awareness about preparation. Residents are encouraged to assemble an emergency kit, sign up for phone alerts and formulate evacuation plans.”
Closer to home, we remember that the Littlerock Dam has released waters over its spillway when heavy storms supply many tributary flows, splashing down the mountainsides. One time an Eastside bridge was destroyed and it took months to get a replacement.
“We’re going to be enacting a lot of emergency-preparedness activities,” Kristen Bedolla, dam safety program manager for the Corps’ Los Angeles District said. “As we turn the corner toward winter, we’re definitely going to be more proactive in working with our downstream partners.”
The agency will also conduct further studies to assess whether the dam – which goes through regular maintenance and upgrades — needs further hardening. Interim measures also are being considered before the rainy season arrives in the coming weeks.
“How big is the risk?” Ortiz asked.
He answered “It’s minimal, but it does exist. The dam is about 200 feet high, and its highest watermark ever, 72 feet in 2005, did not reach the halfway point. The emergency spillway has never been used.”
Lillian Doherty, chief of the operations division for the L.A. District, said that chances of water flowing over the dam are .01% on any given year.
The USA Today writer pointed out that in February 2017, both spillways for the Oroville Dam in Northern California were damaged by floodwaters, and 190,000 people had to flee their homes.
“Is climate change a factor?”
Ortiz wrote “Of course. Although the Mojave River Dam, built in 1971, has been performing as designed, old weather models no longer accurately predict what conditions to expect. Evidence of climate change has been a motivator in the decision to further assess the dam’s ability to withstand extreme floods.
“That is our mission, to reduce the risk for the communities we serve,” Doherty said. “With climate change, we are seeing more severe events on a more regular basis.”
“Floods in the desert, really?” Ortiz asked.
The Mojave Desert primarily located in southeastern California and southern Nevada, is regarded as the driest desert in North America, with an average yearly precipitation of less than five inches. The western part is not quite as parched, average 6.7 inches, mostly stemming from winter storms rolling east from the Pacific. When that happens, the water can accumulate quickly in areas not used to it,” he wrote.
“We have a very reactive system,” Doherty said. “Just a little bit of rain can cause huge flash floods in any area including the desert.”