What does it mean for a basin to sustainably manage groundwater?
To manage and use groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results (Water Code §10721(v), meaning one or more of the following effects caused throughout the basin:
(1) Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply over the planning and implementation horizon. Overdraft during a period of drought is not to establish a chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reductions in groundwater levels or storage during a period of drought are offset by groundwater levels or storage during other periods.
(2) Significant and unreasonable reduction of groundwater storage.
(3) Significant and unreasonable seawater intrusion.
(4) Significant and unreasonable degraded water quality, including the migration of contaminate plumes that impair water supplies.
(5) Significant and unreasonable land subsidence that substantially interferes with surface land use.
(6) Depletions of interconnected surface water that have significant and unreasonable adverse impacts on uses of surface water (Water Code §10721(x)).