Flood Control District

Mohave County, even with its desert climate, has the potential for major flooding events. Floods in the County have caused damage claims totaling millions of dollars.

Mohave County has a natural system of washes, streams and rivers that can carry off and drain accumulated rainfall. Rainstorms can fill rivers and washes outside the County, sending floodwaters through tributaries into the Mohave County landscape.  Flooding in the County also occurs when the ground cannot absorb the rainfall from a short but heavy storm.   

Sources of Flooding in Mohave County

Mohave County is affected by the rapid development that has taken place in our area. The growth of the County's population over the years has produced significant urban development. In many early cases, streets, roads, and subdivisions were developed with little regard to the County's natural drainage basins and natural storm conveyance channels. Buildings, homes, paved streets and parking lots have disrupted the natural flow of water and prevented the water from being absorbed into the ground as it would in a natural, undeveloped state. This has created inadequate drainage in some areas.

Mohave County experiences two active precipitation seasons each year with a high frequency of severe storms. The first rainfall season occurs from November to March. Winter precipitation is greatest when the storm track enters the state from the west or southwest after picking considerable moisture from the Pacific Ocean. In fact, some of the most damaging floods have occurred from winter storms outside the County such as the Beaver Dam Floods of January 2005 and December 2010.
The second rainfall season, known as the "summer monsoon," occurs in July, August and September when the County experiences widespread thunderstorm activity associated with moist air from the south and southeast. These thunderstorms are extremely variable in intensity and location, and can produce heavy amounts of precipitation in short periods of time. The flooding that may result is localized and short-lived, however the damage can be severe.

Flooding and Development

Mohave County is located in north-western Arizona. Geographically, it is the second largest county in Arizona and is ranked the 5th largest county by land area in the entire United States.  It has a land area of 13,479 square miles, of which nearly 98 percent is unincorporated.