Approximately 14 miles in length, the Transition Zone has been a key stretch of the Mojave River in terms of evaluated water supply needs and conditions in the basin. The area extends from the U.S. Geological Survey Gauging Station at the Lower Narrows downstream to the Helendale fault near Silver Lakes.

In 2002, the Agency’s Board of Directors authorized a Transition Zone Recharge Study designed to define the geology and water supply characteristic of the Transition Zone and evaluate future water demand in the area.

The study was conducted in two phases. The first focused on basic hydrologic evaluation, the second phase focused on future imported water needs in the upper Mojave River, and possible locations for recharge facilities there.