Floods, aftermath nothing new to Las Vegas Valley

Tuesday, Feb. 22, 2000 | 10:59 a.m.

Locals tell newcomers that the flood season in Southern Nevada is July through September, but a check into the weather history of the 20th century shows that floods can and have occurred during every month of the year in the Las Vegas Valley.

From 1905, when the City of Las Vegas was founded, to 1975 the U.S. Soil Conservation Service documented 184 different floods that damaged public and private property.

In the past 40 years, 25 people have been killed in 12 separate flash floods. Two more people lost their lives in last year's flood July 8, one a homeless person and another in a rain-related car accident.

Perhaps the largest single loss of life occurred in Clark County on Sept. 17, 1961 when nine people -- four Nevada Power linemen and five Boy Scouts -- were killed during a storm that struck the area after dark. The Nevada Power crewmen died trying to restore electricity to the valley. The Boy Scouts drowned after they were washed out of Zion National Park, more than 70 miles northeast of Las Vegas. Their bodies were recovered near Mesquite, 65 miles northeast of Las Vegas, in the Virgin River.

Since 1960 the area has experienced at least nine "million-dollar floods," including the latest one last July.

That flood caused more than $20 million in damage to public roads, buildings and flood control structures, according to Clark County records and the Federal Emergency Management Agency.

While floods can occur at any time, the most damaging of them typically strike the valley in July and August when moist, unstable air from the Gulf of Mexico meets hot, dry air over Nevada and Arizona causing downpours, according to the National Weather Service.

Most residents or visitors to the valley see dry gullies and washes most of the year, but as Monday's storm proved, an inch of rain in 24 hours can flood streets, the Charleston Underpass and the Las Vegas Wash, the valley's outlet leading to Lake Mead where Southern Nevada draws most of its drinking water.

Average rainfall for this time of year is 0.86 inches, but Southern Nevada surpassed that benchmark on Monday.

The average rainfall for the valley as measured by the National Weather Service at McCarran International Airport is slightly more than 4 inches per year.