Pinal County farmers will likely have to reduce their use of Colorado River water by 40% in coming years as the state’s 20-year mega-drought continues and the reservoirs on the Colorado River dwindle.
Arizona’s now facing a water crisis that could dry up rural areas all over the state and confront the Valley with a crippling water shortage in the coming decades, according to a recently completed study by the Center for Colorado River Studies.
The Valley and Tucson will also have to reduce their share of Colorado River water by 40% in coming years – and that’s likely the best case scenario, the study concluded.
The state Legislature for the past five years has repeatedly failed to cope with a water crisis now afflicting much of rural Arizona – especially in the southern and eastern portions of the state.
Back in 1980, Arizona won federal approval of the $4-billion Central Arizona Project by agreeing to impose groundwater management plans on Maricopa, Pima and Pinal counties. The plans require developers to certify they have a 100-year water supply to support new development. However, groundwater pumping in some parts of rural Arizona remains unregulated.
Corporate farming operations that can afford million-dollar wells have pumped groundwater in unregulated parts of the state, which do not include Pinal County. One investigation by the Arizona Republic showed that a quarter of the wells in Arizona’s groundwater monitoring program have dropped by more than 100 feet. Most continue to drop by an average of about three feet per year.
Last year, state lawmakers proposed a total of 12 bills that would provide a way to regulate groundwater pumping in more rural areas, but not one made it to the floor of the House or Senate.
Half a dozen bills have been proposed this year. HB2679 would allow county supervisors to create rural management areas to protect the groundwater. HB 2595 would make it possible to bar the expansion of irrigated farmland in a county with projected problems with the water table. Several other bills including SB 1079, HB2741 and HB2204 would take steps to protect the San Pedro and Verde rivers – both in danger of drying up as water tables decline. Yet another bill – SB1314 – would require well owners pumping more than 35 gallons a minute to report to the state on their water withdrawals.
The growing groundwater crisis in rural areas comes just as the low flows on the Colorado River have prompted water rationing throughout the region – with far worse to come, according to the effort to predict river flows through mid-century.
The Lower Basin states of Arizona, Nevada and Colorado will have to cut their share of water from Lake Mead and Lake Powell by 40% by the 2050s to keep from emptying the reservoirs, eliminating power generation and causing a major water shortages throughout the region.
And that’s the optimistic scenario – based on a continuation of the current climate conditions as well as the assumption that the four upper-basin states will continue to be less than half of their legal entitlement. If temperatures continue to rise, it will get far worse – with river flows dropping y 7% for every 1 degree Celsius increase in temperature, the study concluded. The shortfall could total 30% by 2055 and 55% by 2100.
So far in this century, the river’s flow has already dropped by 18% compared to average flows in the 20th Century.
An agreement involving all seven of the Colorado River Basin states early in the 20th Century allocated some 15 million acre-feet in the river’s annual flow. The four upper basins states are entitled to 7.5-million acre-feet annually, but are now using only about 3 million acre-feet. The three lower-basin states have a lower priority use but can also claim 7.5 million acre-feet.
However, it turns out that the river’s flow was closer to 12 million acre-feet in the second half of the 20th Century. In recent years, flows have declined even further – resembling the worst known dry period on the river. Between 1576 and 1600, flows dwindled to just over 11 million acre-feet annually, according to one comprehensive tree-ring study.
Lake Mead and Lake Powell have for decades cushioned the overallocation of the river. However, they’re both now half empty, with continuing declines triggering rationing that will hit the lower-basin states hardest. California has higher priority than Arizona and Nevada, which means the desert states will bear the brunt of any cutback.
Almost all of that represents bad news for Arizona’s future water supply, with most projections calling for round after round of water rationing across most of the state in coming decades. Rural areas like Willcox and Kingman could find the big corporate farms will suck dry the water table before moving on, leaving whole regions all but undevelopable.
Peter Aleshire is Consulting Publications Editor for the Payson Roundup, a division of parent company Kramer Media.