BULLHEAD CITY — Forty-five percent of Arizona is now in extreme drought according to the Arizona Drought Monitoring Technical Committee.
The committee released a report last week showing statewide drought conditions worsened during March. The continued dryness led to drought declarations on the Navajo Nation and in Yuma County.
Though a series of weak storms passed through Arizona, they left only insignificant snow, according to the report. The southern half of the state remained dry and northern Arizona received only scattered light precipitation. The committee noted rangeland conditions are very poor with little forage, and water hauling for both livestock and wildlife has begun in many parts of the state.
Water in the Colorado River is generated by snowmelt runoff from mountain ranges as far away as Wyoming and Colorado.
As of April 2, the Upper Colorado River basin snowpack stood at just 72 percent of normal, resulting in a runoff season that may be the sixth driest since Glen Canyon Dam and Lake Powell have been in place to capture the runoff, according to a report on the Arizona Department of Water Resources website.
The Colorado River system, which provides Arizona with about 40 percent of its water supply, has experienced severe drought conditions since 2000.
Water levels in Lake Mead, the primary storage reservoir for the Lower Basin states — Arizona, California and Nevada — have been declining and projections indicate this will continue into the foreseeable future, according to ADWR.
Forecasters also predict runoff into Lake Powell, which supports the Upper Basin states north of Arizona’s Lee’s Ferry — Colorado New Mexico, Utah and Wyoming — will be only 43 percent of normal this year. ADWR reported this year’s projection for in-flow into Lake Powell is 3.1 million acre-feet, less than half its average 7.1 million acre-feet.
An acre-foot of water is 325,851 gallons, enough to cover an acre of land with a foot of water. It’s enough water to support three households for one year.
U.S. Bureau of Reclamation reports as of Tuesday showed Lake Powell is 56 percent full and Lake Mead is at 41 percent, with an 1,087 foot elevation, roughly 12 feet above the 1,075 elevation that would trigger automatic first tier shortages for Central Arizona Project deliveries.
BuRec does not anticipate any level of shortage in Lake Mead for 2018, but increased the probability of shortage in 2019 from 15 percent in August 2017 to 17 percent probability now. BuRec’s Colorado River Simulation System model also increased the probability of shortage in 2020 by 7 percent, in 2021 by 13 percent and in 2022 by 11 percent.
Worse, ADWR officials said, in-state river systems are historically low; provisional data for runoff in the Salt and Verde reservoir systems show the January through March runoff totals are “the lowest amounts on record dating back to 1913.”