“It’s a desert out there. Be water smart.” That’s the slogan used by the Southern Nevada Water Authority to remind us locals to conserve water. But the same slogan could be used to convey the situational awareness we need to survive a summer rainy season here in Las Vegas.

Those who have never seen the awesome power of a Las Vegas summer rainstorm often scoff at the potential for flash floods in the valley. I have a hard time myself believing a parched expanse of sand and sagebrush could explode into a raging torrent in a matter of minutes. But violent rainstorms occur here every summer, and their effect can be freakish.

True, the average annual rainfall in Las Vegas is only 4 inches a year, but I have seen storms drop what would have been more than 2 inches an hour — if it had rained that long. Most of our summer storms last less than 15 minutes, but these storms can be very intense. In fact, it’s not uncommon to see tornado vortex signatures form in the middle of some of these storms, although they rarely last long enough to reach the ground. Because desert soil is almost as impermeable as asphalt, even a short thunderstorm can result in astonishing amounts of flood water.

A couple of years ago, a simple trip to the grocery store turned into a whitewater adventure when a sudden thunderstorm turned the seemingly-flat parking lot into a cascade of white froth. My car, a four-wheel-drive SUV, was picked up by waves of water pouring in from the street. I went for a spinning, unexpected joy ride of about 50 feet before I was able to regain traction and head for higher ground. (For another exciting desert adventure, check out Megan Edwards’ description of being caught by a flash flood near a dry lake bed south of town.)

The Clark County Regional Flood Control District was created in early 1985 and tasked with the monumental job of channeling and controlling the runoff of summer thunderstorms in southern Nevada. As with flood control districts elsewhere, funding for the projects is provided by state taxes and through the U.S. Army Corps of Engineers. Construction on the first flood control facilities began in 1988 and total spending has now exceeded $1.2 billion.

As of last year, the district had completed 75 retention basins; it intends to build nearly twice that number over the next 30 years. These retention basins are huge, and new residents probably shake their heads at what appear to be massive plots of empty land in their neighborhoods. Two of these enormous basins lie within five miles of my house, and I’ve been watching construction crews working every day building connecting concrete channels. Now, while everything is Sahara-dry, their work looks completely unnecessary. I have to remind myself that in the eight years I’ve lived here, I’ve seen the residential roads that parallel these brand-new channels completely washed out by short-lived rainstorms.

In addition to water control projects, the Flood Control District maintains sensors in 150 rainfall-measuring devices set out around the valley to report water levels and other weather data to agencies tasked with issuing flood alerts. This operation, known as the “Flood Threat Recognition System,” publishes its data on a Web site. It’s a pretty amazing bunch of graphs to check out in the midst of a rainstorm here in town! But then again, I’m a weather junkie. I love watching ice-cold super thunderstorm cells form and collide with the hot air rising from the desert floor. In the summer months, I keep my weather radio close by, and I monitor the radar stations as I wait for the next big storm.

In fact, in the last 15 years, I have seen at least four weather events that were classified as being “100-year storms.” No, this does not indicate a short-term memory problem on the part of the newscasters. It turns out that more than one 100-year storm can strike in one century. The term doesn’t denote historical frequency; rather, in good Vegas fashion, it states the odds of such a severe storm hitting in a particular year, i.e., there is a 1 percent chance that a 100-year storm will hit in any given year. Which means, for a weather junkie, I’ve just been extraordinarily lucky.

But not everyone who encounters a Vegas flood has been lucky. In fact, storm water can be a killer, and in the last 30 years, more than 35 Las Vegans have died in flood-related incidents. Hence, some advice.

If you happen to be near a flooded street or in the proximity of a flash flood, don’t try to drive through it. You can’t tell how deep the water is by looking at the surface — I have seen cars sink up to their windows into what looked like no more than a shallow puddle. Even more risky is attempting to walk through flash flood water. Even an obviously shallow flow can knock you off your feet, because the water can travel at speeds up to 30 miles an hour and it’s often full of storm debris.

Because flood waters look benign to people who don’t know any better, the Flood Control District has sponsored a billboard campaign featuring real photographs of hapless motorists who drove into flooded areas. Clever captions on vanity license plates convey a series of warning messages.

My own recommendation is to banish this one seductive thought: “I think I can make it.” That way you’ll never see a picture of your car on a billboard or squander your 15 minutes of fame appearing as a drowned rat on the “6 O’Clock News.”