Gentle Raindrops Welcomed : Millions of Gallons Captured; Next Storm to Arrive on Sunday

The relatively weak tropical storm that pushed through drought-stricken Orange County was welcomed by local water officials, who said Friday that they captured millions of gallons of rainwater for the diminished underground water supply.

While warning that the storm, which dropped as much as two inches in some parts of the county, did not come close to solving the county’s chronic water supply problems, authorities said that the sometimes gentle rain showers are preferable to drenching downpours.

Too much rain at a time, they explained, would end up in the ocean without replenishing the water table.

“It’s a nice storm, not big enough to require flood control but big enough for water conservation,” said Greg Grigorian of the Army Corps of Engineers, which operates Prado Dam. “It hasn’t been heavy, which gives us enough time to catch the water in the spreading basins downstream.”

Meteorologists said Thursday’s storm was a precursor to a series of light to moderate storm fronts that should keep Orange County on the moist side for the next week.

The warmer-than-normal storm, which formed in the west Pacific Ocean, gave way to gorgeous sunshine and picturesque clouds Friday, allowing residents a short respite before two colder storm fronts move into the region.

Mild temperatures and clear blue skies were predicted for today and into Sunday morning, said Steve Burback, a meteorologist with the Wichita, Kan.-based WeatherData Inc., which provides forecasting for The Times

By Sunday afternoon, he said, a storm that has been brewing just south of the Aleutian Islands will reach California and provide rain showers. The rain is likely to remain throughout Monday, with clearing by Tuesday.

On Wednesday, the last of the three back-to-back storms is expected to pass through the Southland, lingering for about a day before moving out of the state, said WeatherData forecaster Ric Ditman. By the end of the third storm, the snow level is expected to drop below 5,000 feet in the San Gabriel and San Bernardino mountains.

“It looks like we are in for a real wet weather pattern,” Ditman said.

Law enforcement authorities plagued by fender-benders over the past two days expressed relief on Friday at the first storm’s passing.

“We’ve only had a fourth of the crashes we had yesterday,” said Anaheim Police Sgt. Ken Brott. “They (drivers) seem to be behaving themselves.”

The California Highway Patrol also reported a sharp drop in the number of accidents. While more than 100 traffic accidents were reported on the county’s freeways Thursday, Friday was almost vacation-like in comparison, said CHP Officer Angel Johnson.

“People weren’t quite so bad today,” she said.

Nevertheless, as the storm dumped its last vestiges of rain, two rain-related traffic problems tied up the early commute in North County.

The driver of a tractor-trailer rig heading west on the Riverside Freeway lost control of the truck, which jackknifed and closed one lane of the rain-soaked freeway, Johnson said. A fuel tank on the rig was punctured, spilling diesel fuel over the wet roadway.

On the Orange Freeway a short time later, rain caused a van to stall, backing up southbound traffic for miles. “That one was really a problem,” Johnson said, adding that “we’ve gotten so many calls on stalled vehicles today. It always happens in the rain.”

Santiago Peak in South County received the most rainfall, measuring 2.24 inches, according to the county Environmental Management Agency. In Cypress, 1.54 inches of rain fell, while in Santa Ana, 1.35 inches of rainfall was recorded.

Rainfall was lightest in Irvine, Mission Viejo and Lake Forest, where 0.79 inches of rainfall was recorded, the county reported.

Water officials said the rain is by no means a drought-buster. But it helps replenish Orange County’s ground-water supply, which is the source of about half of the water consumed in the county. The other half is imported from the Colorado River and the drought-plagued Sierra Nevada.

In all, the two days of light rain provided about 1,000 acre-feet, or 326 million gallons--only enough to provide a day’s worth of ground water for 2 million residents of north Orange County.

This week’s rainfall, however, has been the type that local officials like to see--big enough to capture some flow in reservoirs, but not so big that water rushing down the Santa Ana River becomes a flood risk and has to be dumped into the ocean.

Since Thursday, millions of gallons of storm water has has filled Prado Dam, and the Army Corps of Engineers has been releasing it slowly so that it can be collected and stored in large spreading basins downstream in Anaheim, officials said.

The dam is on the Santa Ana River just over Orange County’s border in Riverside County.

“By end of this week or two, we will have a lot of water saved for Orange County Water District,” Grigorian said, referring to the coming storms.

The last stretch of foul weather dumped about 195 million gallons of water into the series of catch basins and reservoirs along the Santa Ana River, Grigorian said.

Another 100 million gallons is still behind the dam and will be released slowly into those basins over the next couple of days, while runoff will probably contribute another 40 million gallons.

That is a drop in the bucket for Orange County, which uses about 108 billion gallons of ground water per year.

Nevertheless, “every drop helps, absolutely,” said Jim Van Haun of the Orange County Water District.

The dam keepers, however, are watching for bigger storms.

If the water behind the dam rises to 494 feet--another 13 feet--the Corps must release it all quickly into the ocean to prevent floods downstream in Orange County and to protect the nesting grounds of the least Bell’s vireo, a small endangered bird, Grigorian said.

Last year, during heavy March storms, millions of gallons of rainwater were allowed to flow uselessly into the ocean because of the Corps’ policy of protecting the birds.

But after the public expressed outrage at the wasted water, the Corps, the water district and federal wildlife biologists held emergency meetings and agreed upon a way to store more water yet protect the vireos.

The agreement, however, expired last year, and new negotiations between wildlife officials and water officials recently began. Van Haun said a new agreement is in the works, possibly by March 1.

WeatherData’s Marty McKewan agreed that the persistent storminess does little to relieve the drought locally, saying that the answer to county’s water supply will be found in the high mountains of Northern California.

“What we really need is a good couple of feet of snowfall,” McEwan said. “That would be ideal.”

Banking Water Against the Drought

Orange County has drawn more heavily from its underground water basin to make up for its drought-reduced water supply from the Sierra Nevadas. While local rainfall replenishes the basin, levels will drop again unless Sierra snowpack returns to normal. What Happens to Rainwater Watering the lawn Most local rainfall only soaks lawns and gardens. It does not reach the county’s underground aquifer hundreds of feet below the surface. Prado Dam The dam captures rain, which can be channeled into the underground aquifer. But the dam cannot be filled to capacity because water would cover the habitat of an endangered bird, the least Bell’s vireo. Recharge Basins Water channeled into several catch-basins sinks into the aquifer. The water is pumped up for later use. Underground Aquifer The aquifer provides most of north Orange County’s water, reducing the need for imports. South Orange County depends mostly on imported supplies. County’s Overall Water Supply During a normal year, Orange County draws water from supplies shown. Sierra shortfalls have been made up from local and Colorado River water supplies. Underground aquifer: 50% Sierra Nevada: 25% Colorado River: 25%

STORM TOTALS In inches, as of 8 a.m. Friday Santa Ana: 1.35

Santiago Peak: 2.24

Costa Mesa: 1.28

Mission Viejo: 0.79

Corona del Mar: 1.18

Irvine: 0.79

Westminster: 1.30

Cypress : 1.54

Fullerton: 1.22

San Juan Capistrano: 0.87

Laguna Beach: 0.94

* As of Thursday 5 p.m. Source: Orange County Water District, Orange County Environmental Management Agency; Researched by DANNY SULLIVAN/Los Angeles Times