Flood project opens land to development

Jeff Schweers

Monday, June 2, 1997 | 11:59 a.m.

Summerlin South wouldn't be possible without a $258 million flood control project being built by the U.S. Army Corps of Engineers, Clark County Public Works Department and the Regional Flood Control District.

Due for completion in 2006, the decade-long project to build a system of catch basins and channels in the Tropicana and Flamingo wash areas is opening thousands of acres to development by taking it out of a historic flood zone.

Without the project, developers would have to invest millions of private dollars making the southwest Las Vegas Valley suitable for homes, business parks and shopping centers.

"We want to be careful about that," said Kevin Eubanks, who helps remap the federal flood insurance zones for the Regional Flood Control District. "The enabling legislation is clear that we're supposed to protect our existing development and people from existing flood hazards. We're not here to spend money to provide for development."

Once completed, however, the project is going to solve a lot of flooding projects in the southwest valley, Eubanks said. "As a side benefit, it will open areas to development."

Another side benefit is homeowners won't have to get flood insurance when they take out a bank mortgage, Eubanks said. Banks are required to have mortgagees buy insurance if they live in a federally mapped flood zone.

That isn't to say homes and apartments couldn't be built in the flood plain, Eubanks said, "but it would cost developers a lot more and development would not be approaching drainage on a regional basis. Project by project, they would have less chance for success."

Denis Cederburg, manager of the design engineering and management division of the Clark County Public Works Department, said developers have to provide drainage studies and show how they will manage run-off flow before their projects can be approved.

Building their own facilities costs more for the developer, but is the only alternative if they want to start building before public flood control facilities are built, Cederburg said, "because they can't rely on facilities that are not there."

"If they did," he said, "they couldn't build until those facilities were in place."

The project also is being coordinated with the construction of the Las Vegas Beltway, to ensure that the freeway doesn't get washed out during a flood, Cederburg said.

The project is part of a valleywide flood control system that will cost $1.2 billion and take the next 25-30 years to complete, said Gale Fraser, director of the Regional Flood Control District.

"Drainage is the only infrastructure issue that is not growth-related," Fraser said, explaining that the system is being built to protect people and property.

Since 1960, 22 people have lost their lives in nine separate flash floods, and the valley has had seven "million-dollar floods," which caused in excess of $7 million in damage to public and private property.

The corps did a cost-benefit analysis in the early 1980s on the project, following the 1981 and 1984 floods that led to the formation of the flood control district, which has itself spent $250 million on flood control improvements since 1987.

Most of that money has come from a quarter-cent sales tax implemented in 1987 and an $80 million bond sold in 1991.

Clark County is contributing 25 percent of the Army Corps project, which deals mainly with the problems of flooding in the west and southwest parts of the valley. The corps project includes expansion of the Red Rock and Upper Flamingo detention basins, the construction of two detention basins in the mountains west of Summerlin, and miles of concrete-lined channels.

Cederburg said the county's job is to acquire right of way, coordinate utility relocations and find disposal sites for debris.

"They said it would be cost-beneficial to provide these to protect the community," Cederburg said.

The project will provide greater protection for a 100-year flood by collecting storm run-off from a 160-square-mile drainage area, funneling it into the detention basins and releasing the run-off through the urban Las Vegas Valley at a lower flow rate.

The expansion of the Red Rock Detention Basin alone has slowed the outflow capacity from 1,400 cubic feet per second to 180 feet per second, Eubanks said. The effect has been to remove from the flood zone about six square miles downstream of the basin -- much of it owned by the Howard Hughes Corp., which is developing Summerlin South, he said.

That isn't to say it's completely removed flooding impacts, Eubanks said. But a developer can mitigate flooding to a lesser degree and market projects without buyers having to buy flood insurance.

"We're proud of that," Eubanks said. "That's one big chunk of the flood zone that just went away."