LAS VEGAS -- Families who have recently moved to southern Nevada may be surprised by warnings of flash flood season. But they’re real.

It only takes about four inches of rain to create flood conditions in the Las Vegas valley, the Regional Flood Control District announced at a news conference Tuesday.

Slideshow: Storms, Flooding Hit Vegas Valley

The average rainfall in the Las Vegas Valley is 4.49 inches, an amount the agency said is nearly equally divided between summer and winter.

Flash flood season lasts until September, and already this week there has been some rain.

This summer, the Flood Control District will begin construction on 33 new projects to cut down on the potential for floods. County leaders said the money, an estimated $230 million investment, will come from the federal stimulus package and could create as many as 3,000 jobs.

A breakdown of the agency’s projects can be found on its Web site.