October 2014, Issue 87: Editor’s Notes

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Groundwater management: Arizona vs. California 

In September, California became the last western state to pass a law to regulate groundwater pumping. This game-changing legislation is long overdue; not only does California sometimes depend on groundwater to meet half or more of its annual water demand, but the state has been under a devastating drought for several years. Because this drought has severely curtailed surface water supplies, some Central Valley basins are experiencing apocalyptic groundwater declines — over 50 feet a year.

ca_wlDeclineMapArizona long ago recognized the negative consequences of groundwater overdraft: reduced well yields, increased pumping costs, land subsidence, degraded water quality, and diminished stream flows. In 1980, we passed the Groundwater Management Act, hailed as the most progressive groundwater-management law in the western U.S. Arizona has also recognized that, in addition to avoiding the negative effects of overpumping, preserving groundwater supplies buffers against drought when surface water supplies are unavailable. We took things a step further in 1996 by institutionalizing water banking at the state level. By comparison, banking or “managed aquifer recharge” is less prominent in California, with most efforts to date undertaken by private interests or local water management agencies.

California, at the forefront in many areas of natural resource management, is a latecomer to groundwater management. Table 1 (below) compares the status of suface water and groundwater management in California and Arizona. In terms of taking steps to protect groundwater and limit dependence on vulnerable surface water supplies, Arizona clearly leads. Regardless of who got there first, Arizonans should welcome the changes in California. Ultimately, we all benefit when each Colorado River Basin state ensures the sustainability of its groundwater supplies.

Groundwater Supplies
Dependence on groundwater statewide 38% of total water use Varies; 50% or more of total water use during drought
Year law was passed to regulate pumping 1980 2014 (takes effect in 2015; plans must be in place by 2020)
Target year (total time allotted for basin to reach “safe yield” (AZ) or  “sustainability” (CA)) 2025 (45 years) 2040 (20 years)
Percent of population living in regulated groundwater basins 82% (in 5 AMAs out of 51 basins) 88% (in 127 “high and medium” priority basins out of 515)
Surface Water Supplies
Severity of current drought (impact on surface water flows) Diminished; lessening Ongoing; no end in sight
2014 shortage declaration (reduced delivery of contracted surface water allocations) None State Water Project: 95% cut
Central Valley Project: 50% cut for M&I, 100% cut (no deliveries) for ag
Historical shortages with statewide water projects (reduced delivery of contracted surface water allocations) Never State Water Project: 22 of 25 years  Central Valley Project: 8 of 11 years