State slips back into severe drought

In fact, the 21-year drought that has renewed its grip on the Southwest ranks as the longest, severe dry spell in nearly 700 years.
The near-normal winter and decent monsoon offered hope we’d finally escaped the drought, but the bone-dry autumn and prospects for a dangerously dry winter have allowed the drought to set its teeth around the throat of the Southwest once again.
The University of Arizona Tree Ring Lab has confirmed that the six-year dry stretch interrupted by snowfall in the winter of 2016-17 marked the marked the longest way-below-normal spell in 675 years.
The U of A Tree Ring Lab has an unparalleled record of such growth ring samples from throughout the region.
The records going back more than 700 years do show several periods with lower average rainfall than the past 21 years.
The so-called Medieval Warm Period lasted from about 950 to 1250, the warmest stretch since the so-called Roman Warm Period from 250 B.C.
The Medieval Warm Period was followed by the three cold periods termed the Little Ice Age in the 16th and 19th centuries.
The tree ring record does show two similar five-year dry spells, one in the 1590s and one in the 1660s.
The spring runoff in 2017 snapped the six-year losing streak, finally providing runoff a little above the long-term average, according to the Salt River Project.
Lake Mead, the reservoir behind Hoover Dam, stands at about 39 percent capacity.

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