The Mojave River is the lifeblood of the desert. Flows in the river cause a majority of the natural groundwater recharge that occurs within the Mojave Basin. Tributaries to the river originate primarily in the San Bernardino Mountains, with the West and East forks merging behind the Mojave River Dam in southern Hesperia.
In an average year, a little over 50,000 acre-feet of water enters the Mojave River and percolates into local groundwater basins. However, that amount can vary tremendously depending upon the amount of rainfall in the mountains. Flows recorded since the early 1900’s have ranged anywhere from under 10,000 to over 400,000 acre-feet in a year. For planning purposes, the MWA looks at the long-term average flow as the basis for water supply the area receives from the river.
Map of the Mojave River and Water Table
The river also serves as MWA’s main groundwater recharge outlet. A majority of MWA’s State Water Project imports are recharged at sites along the river. When natural surface flows subside, the sandy soil conditions in the dry riverbed make for an ideal place to quickly percolate large volumes of imported water.