Most of the southwest, parts of California and the southern and central Great Plains will be the most vulnerable areas in the US to water shortages during the next 60 years, according to a US Forest Service Report.
The report, “Vulnerability of US Water Supply to Shortage: A Technical Document Supporting the Forest Service 2010 RPA Assessment,” compares projected future water demand and supply across the contiguous United States. The report modeled demand and supply on an annual basis for 98 river basins called assessment sub-regions, or ASRs.
Increases in population and economic activity will not, by themselves, pose a serious threat of large-scale shortages because of improvements in efficiency, the report concluded. But it warned that climate change can increase water demand and decrease water supply. This makes future shortages likely, especially in the larger southwest, unless major adaptation efforts are taken.
For the US as a whole, precipitation is expected to decline by more than 30 percent of current levels by 2080 for some scenarios examined, according to the report. In some particularly vulnerable regions of the US, important reservoirs are left with little or no water.
In about one half of the ASRs where vulnerability is expected to increase, decreases in water yield and, in turn, water supply, have a greater effect than do rises in water demand. The reverse is true in the other ASRs.
The report concludes the projected levels of vulnerability in some ASRs are untenable, suggesting that adaptation will be essential. Adaptation options might include groundwater mining, reductions in in-stream flows, water transfers, water conservation beyond the levels assumed in the report, population shifts and alterations of reservoir operating rules.
In 2003, the General Accounting Office issued a report warning that by 2013 at least 36 states could face water shortages. But by 2008, at least 36 states were already dealing with periodic if not chronic water shortages, with California, New Mexico, and Arizona at the top of the list, according to a report released in January by urinal maker Waterless Co.
Earlier this month, the US Army Corps of Engineers said it will begin issuing permits for industrial and municipal uses of Missouri River water, and is considering charging for surplus river water in the future.