U.S. Gives $100 Million More to Raise Height of Dam

Daniel Spera can’t point to the Prado Dam on a map or explain the hydrological science behind a $472-million plan to raise its walls.

But the Huntington Beach office manager is acutely aware of how it affects his pocketbook. If the dam is raised, he and tens of thousands of other homeowners living in the vast Santa Ana River flood plain will no longer be required to purchase costly flood insurance.

“I pay $500 a year. That would cover a lot of Christmas presents for the kids, or a trip to the mountains,” Spera said. “It would get rid of a pretty big expense.”

The dam-raising is the final piece of the mammoth Santa Ana flood-control project, a $1.3-billion effort aimed at protecting what federal officials describe as potentially the most vulnerable flood plain west of the Mississippi.

The long-delayed elevation of the dam won a big boost earlier this month when the U. S. Army Corps of Engineers agreed to pay an additional $100 million of the costs, raising its share from 30% to 50%. The county is now optimistic that the project will be built, but money is still needed from the state to fully fund the work.

The plan is to increase the storage capacity of the dam by 50%, reducing the pressures to release water into the Santa Ana River. Although the river’s flow is now down to a trickle during the dry summer, the Santa Ana can turn destructively wild in the rainy season, and releases from the dam aggravate the problem.

Officials said the river is overdue for a great 100-year flood, which could cause an estimated $15 billion in damage and the deaths of 3,000 people.

One such flood occurred in the late 19th century, when settlers wrote of rowing boats from Newport Beach to Santa Ana. Another massive flood in 1938 knocked out nearly every bridge in the county, submerged large parts of Garden Grove, Westminster and Santa Ana and killed dozens of people.

Built in 1941, the Prado Dam sharply reduced flood dangers in central Orange County and made possible the dramatic postwar urbanization. But the Corps later determined that the Prado could sustain nothing greater than a 70-year flood and urged that the dam be raised.

“To most people, this dam is a financial issue because of the insurance,” said Fountain Valley Councilman John J. Collins, whose city lies in the heart of the flood plain. “But it also gives us peace of mind.”

About 40,000 homeowners along the river are now required by the Federal Emergency Management Agency to have flood insurance, far more than in any other Southern California county, including Los Angeles.

The agency determines which areas must have insurance by predicting the amount of water that would accumulate during floods so severe that they are expected to occur only once a century, and then overlaying these 100-year flood depths on topographical maps to determine where flooding would be most severe. Zones that would accumulate more than a foot of water are required to have insurance, said Jack Eldridge, chief of the agency’s community mitigation program.

The agency agreed last year to reduce flood insurance rates in the flood plain by as much as 50% or more, because the Santa Ana flood-control project had reached the halfway point.

For example, the annual insurance premium on a home valued at $150,000 dropped from $690 to $326.

Eldridge said the insurance requirement would be eliminated altogether if the county protects the flood plain against a 100-year flood--something that can only occur with improvements to Prado Dam.

Plans call for the county to raise the elevation of the dam--located off the Corona Expressway in Riverside County--from 566 feet above sea level to 594 feet. The improvements require the acquisition of more than 1,700 acres of private property that would be flooded when the dam is raised.

Officials have encountered opposition from some environmentalists and property owners unwilling to sell their land. Still, the county hopes to complete the project by 2005, said William L. Zaun, the public works director.

The total cost of the dam-raising is $467 million, and before the Corps decided to kick in nearly $100 million of the cost, the county and state share was roughly 71% of the total, or $330 million.

The increased federal contribution now means that the state and local portion of the bill will fall to $233.5 million, or exactly half the cost. Of that $233.5 million, the state could pay as much as $163.5 million, leaving the Orange County Flood Control District to pay only $70 million.

The dam-raising, along with a massive widening of the Santa Ana River, should protect the county against the kind of flood that occurs every 190 years--exceeding the 100-year protection necessary to drop mandatory flood insurance.

But officials said the extra protection is only prudent, given the unpredictable nature and catastrophic flood potential of the Santa Ana River.

Like many rivers in the West, the Santa Ana rages during the rainy season but trickles in the dry months. Today, it runs in a fairly straight line from Yorba Linda south to the ocean just north of Newport Beach. But 19th century Spanish land grant maps showed the river curving west from Buena Park and emptying into the ocean near Seal Beach.

Another great flood is “not a matter of if, it’s a matter of when,” said Supervisor Jim Silva, who has lobbied state and federal officials for dam funding. “This is an investment to protect our residents against a natural disaster that is very real. It’s a small price to pay considering the damage a major flood could cause.”