The Indio Subbasin Alternative Plan continues water management efforts began in 2002 with development of the 2002 Coachella Valley Water Management Plan, while updating Subbasin information and management strategies in compliance with new State regulations. The Alternative Plan will describe a pathway for managing the groundwater basin and describe measures to ensure that the Indio Subbasin operates within a sustainable goal for groundwater use. See the “What is the Alternative Plan” below for more information.
The Indio Subbasin has been managed for many years by the local water agencies. The Subbasin is divided into two management areas: the West Whitewater River and the East Whitewater River management areas. The dividing line between these two management areas is an irregular line (see map below) which stretches between Washington Street and Point Happy to the Indio Hills near Jefferson street.
The West Whitewater River management area is jointly managed by Coachella Valley Water District and Desert Water Agency under the terms of the 1976 Water Management Agreement. The East Whitewater River management area is managed by the Coachella Valley Water District. Desert Water Agency and Coachella Valley Water District operate a groundwater replenishment program to help fund groundwater recharge into the Indio Subbasin. CWA, IWA, and other large private and municipal pumpers pay a “Replenishment Assessment Charge” for each acre-foot of groundwater pumped.
The earth has limited supplies of water. Groundwater and surface water are essentially one resource, physically connected by the water cycle in which water evaporates, forms clouds, and falls to the ground as rain or snow. Some of this precipitation seeps into the ground and becomes groundwater that moves slowly into an underground aquifer. If there is no precipitation, then there is no water returning to the groundwater below and the groundwater supply is not “recharged” or refilled.
SGMA defines groundwater sustainability as “the management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results.” What does this mean? A sustainable groundwater basin is one in which the water use is balanced with the water replenishment from rainfall, surface water, and other sources.
Groundwater basins can be replenished naturally and artificially when water from the surface is allowed to seep into the soil. The Indio Subbasin is replenished naturally with mountain precipitation that flows downstream to the Whitewater River. Water agencies in the Coachella Valley also artificially replenish the groundwater with imported water that is pumped into what are known as “recharge ponds” and allowed to seep into the ground.
A groundwater basin is made up of several layers of aquifers, typically separated by different soil or rock types. Water fills the spaces under clay and in between the sand and gravel. Water within the Indio Subbasin slowly moves from the upper valley in the northwest towards the Salton Sea in the southeast.
The Indio Subbasin is part of the Coachella Valley Groundwater Basin, which is designated as Basin No. 7-12.01 in the DWR Bulletin 118 (DWR, 2003). See map below. The basin is surrounded by the San Bernardino Mountains on the north, the San Jacinto and Santa Rosa Mountains on the west, the Little San Bernardino Mountains on the east and the Salton Sea on the south. Adjacent groundwater subbasins are also shown in the map below.