Zone 7 has established as one of its main planning criteria, the ability to meet water demands, even during times of drought. This is to protect against emergency curtailments in deliveries of water from the SWP or water treatment plant outages. Conjunctive use means actively managing the aquifer systems as an underground reservoir. During wet years, when more surface water is available, surface water is stored underground by recharging the aquifers with surplus surface water. During dry years, the stored water is available in the aquifer system to supplement or replace diminished surface water supplies.
Conjunctive use is an effective tool for increasing the overall water supply.
To protect its customers in a prolonged drought, Zone 7 has entered into several long-term water transfer agreements to supplement its regular surface water and groundwater supplies. Proper planning, along with construction and utilization of efficient facilities enables Zone 7 to maintain a water supply system that is highly reliable. The management of storage facilities and their associated conveyance systems is a vital component of Zone 7's ability to deliver a sustainable water supply during dry and critically dry years. This plan assesses the Zone's ability to supply water to its customers by examining present and anticipated weather patterns and water supplies, and mapping out the most efficient use of available surface and groundwater assets. These factors are primarily rainfall, size of snow pack, runoff, water in storage, and pumping capacity in the Delta.