Thunderstorms packing torrential rains may have been a welcome relief from the recent heat wave, but they also wreaked havoc on local roads and highways in the form of flash floods and mud slides.
Inyo County was under a “Flash Flood Watch” Monday night and all of Tuesday as a monsoonal weather system moved through the region, bringing electrical storms, high winds and heavy downpours – which gave the valley more precipitation than it received all winter.
According to the National Weather Service, the Great Basin was one of two areas nationwide with the greatest “flash flooding potential” on Tuesday. Coming in at No. 2 was New England and the Hudson and Delaware valleys.
Local weather forecaster Dennis Mattinson explained the storm was a combination of monsoonal moisture from the east and an upper low pressure system from the Baja Peninsula that drifted north. When the combo reached the Eastern Sierra and ran into the desert heat, the result was convection – or thunderstorm activity, he said. More specifically, the result was “isolated, heavy downpours” which caused flooding throughout the Owens Valley, Mattinson said.
The storm began Sunday night, and grew in intensity Monday afternoon. During the night, the rains took their toll on several roads from Big Pine to Death Valley to Lone Pine.
Saline Valley Road from Big Pine to Death Valley was closed Tuesday morning after flood waters on Monday cut a 40-foot deep by 50-foot wide hole in the roadway, according to Sheriff Bill Lutze. The road will remain closed indefinitely.
Flood waters also wreaked havoc on portions of State Route 168 East, known as Westgard Pass.
According to Caltrans District 9 Public Information Officer Florene Trainor, the entire pass was closed about 8 a.m. Tuesday from U.S. 395 outside of Big Pine to Nevada State Route 266. Crew members set out from either side to locate the damage, discovering huge ruts and “deep gullies” alongside the road as well as portions of highway that had been eroded away altogether near the top of the pass.
As of Wednesday morning, the highway was open again but traffic was being escorted through the pass by pilot cars as crews set about repairing shoulders and cleaning washes, Trainor said. Motorists, she added, could expect no more than 20-minute delays.
Northwest of Independence, the Taboose Creek Trailhead was washed out and four vehicles believed to belong to backpackers were left stranded in a muddy mess. According to Lutze, deputies left notes on the vehicles asking the owners to call the Sheriff’s Department for assistance.
“We’re going to have to get them out,” he said of the backpackers.
South of Independence, Manzanar National Historic Site suffered what a Park Service press release called “significant damage and road closures” as a result of Monday night’s rain.
Overnight, the rains caused the swollen Shepherd and Bairs creeks to overflow, flooding the auto tour road and burying Merritt Park and the Block 12 and 34 gardens.
On Tuesday, staff from the National Park Service and Los Angeles Department of Water and Power were in the process of assessing the damage.
“The blessing of significant rainfall for this parched valley has also yielded an operational challenge for Manzanar,” said Superintendent Les Inafuku. “We’re thankful that our staff and local LADWP crews are safely working to survey the damage and prevent further flooding.”
Manzanar itself remains open to the public, however the auto tour road and west boundary roads will remain closed until further notice, making the cemetery inaccessible by car.
Farther south, Inyo County Road Department crews worked all day Tuesday to re-open Whitney Portal Road, closed Monday night after flood waters deposited “large boulders and debris” in the roadway rendering it impassable, Lutze said. The gateway to Mt. Whitney was re-opened late Tuesday night.
The Trona-Wildrose/Panamint Valley Road remains closed indefinitely after a flash flood Monday evening washed out sections of the roadway and left almost a dozen vehicles stranded.
According to Lutze, the call came in about 6 p.m. and Road Department crews responded along with sheriff’s deputies to find 10-12 vehicles trapped by the water. “They were on high ground, so they weren’t in any danger,” Lutze said, explaining that Road Department employees waited for the waters to recede and then cleared away debris to create an exit route for the motorists.
The road did not fare as well. “It was a pretty good wash-out,” Lutze said.
South of Olancha, two separate mud slides overtook the same section of U.S. 395 near Haiwee Reservoir – one just after midnight Monday, July 22 and the other Tuesday about 4:30 p.m. Both times the highway was closed and motorists were stranded.
The mud slide just after midnight on July 22 took the occupants of a Nissan Titan on a wild, 1.5-mile ride when it came pouring out of the hills and westward toward Haiwee Reservoir.
Three other vehicles were trapped on the side of the highway and buried in mud. One of those vehicles, according to witness Alison Patterson of Bishop, was a Volvo that was pulled out of the mud and towed to the Coso Junction Rest Area. The Volvo, she said, started right up.
The highway, meanwhile, was closed for several hours before being fully re-opened at about 8 a.m.
No vehicles were directly impacted by Tuesday’s slide, according to Trainor, other than being delayed. The southbound lanes were re-opened less than an hour later at 5:15 p.m. and the northbound lanes at 7:07 p.m.
Death Valley, where flash flood warnings are common during summer rain storms, actually fared better than the Owens Valley, at least according to preliminary reports.
Lutze said it took his deputy stationed in Shoshone four-and-a-half hours Tuesday to make what is normally a two-and-half-hour drive, due to standing water, debris and rocks covering the highway. But other than that, he said, no major damage has been reported.
And for now, Inyo County has seen the worst of it – the upper flow has drifted north, Mattinson said – and Lutze, Caltrans, other first responders and motorists can breathe a little easier.
Not that they want the rain to go away. “I wouldn’t mind seeing a little bit of rain every day but not these torrential down pours,” Lutze said, offering a sentiment shared by many in an area that’s endured drought for the past 10 years.
According to Mattinson, these three days of isolated thunderstorms deposited more precipitation in the Owens Valley than it has received all year – a year that featured the “driest January and February in history” and one of the hottest Marches in memory.
“This has been the only measurable rain we’ve gotten so far this year,” he said.
Bishop received a quarter-inch; Big Pine, three-quarters; Independence, a half-inch; Lone Pine, a quarter-inch; and the Alabama Hills, one inch – for a total of two-and-three-quarters inches.
In a good year, not a drought year, the Owens Valley receives an average of six inches of precipitation, Mattinson said.