(CN) – Arizona farmers are bracing for a reduced share of Colorado River water next year as the U.S. Bureau of Reclamation is expected to declare a shortage on the iconic lifeline for more than 40 million people in the bone-dry Southwest.
Leaders from Reclamation, the Arizona Department of Water Resources and the Central Arizona Project, which delivers much of the state’s share of the river to more than half its residents, offered a glimpse Thursday of where Arizona stands with the shortage looming.
A declared shortage, which the bureau is expected to announce in August, would trigger a cascade of actions from Utah to California and squeeze who gets water and how it is distributed among farms, mines, factories, and homes.
But the news is no surprise, said ADWR director Thomas Buschatzke.
“This is a day we knew would come at some point, and we have been preparing for this moment for at least a couple decades,” Buschatzke said.
The now-familiar bleached “bathtub rings” around lakes Mead and Powell, the two largest manmade lakes in the U.S., tell the story. The lakes serve as bellwethers for a shortage declaration, said Daniel Bunk, chief of Reclamation’s Boulder Canyon Operations Office.
Lake Powell is just 35% full and Lake Mead stands at 38% of capacity, leaving each shoreline 140 feet below its full-pool level, Bunk said.
Reclamation forecasts that this year just 41% of the average amount of water will flow into Lake Powell, mostly from melting snow pack. A drought stretching back to 2002 and climate change have led us here, and not only is there less water flowing into the river, but that water is melting faster and earlier in the year, Bunk said.
“The drought has intensified significantly in the past three or four years,” he said.
Things could be worse, Buschatzke said.
Since the current drought began and Lake Powell fell to a record low, Colorado river states have been working together and individually to plan for the expected shortage.
The Lower Basin Drought Contingency Plan, an agreement among Arizona, California, and Nevada, emerged from meetings with more than 40 stakeholder groups in Arizona alone, including mining, agriculture, municipalities, industry, and others.
The plan has helped direct unused water --- more than enough to offset a Tier 1, or lowest level, shortage next year --- to Lake Mead, Buschatzke said.
“We would probably be in Tier 2 if it were not for these actions,” he said.
The full impact on Colorado River water users won’t be known until August, when Reclamation makes a decision on the shortage, said Ted Cooke, general manager of the Central Arizona Project.
Arizona gets 2.8 million acre-feet of the Colorado’s 16 million acre-foot annual allocation. An acre-foot is the amount of water that would over an acre in 12 inches of water – about 326,000 gallons, enough for seven Arizona families annually. But next year the allocation will likely drop by about 512,000 acre-feet, Cooke said.
The drop will only affect agricultural users. One pool, agricultural CAP customers, will lose 100% of their allocation, but all of that will be made up from stored water, water borrowed from the Salt River Project, which supplies Phoenix with water from the Salt River, and water from Native American tribes, he said.
The other agricultural pool, other non-tribal users, will lose about 40% of its allocation, but only some of that will be replaced, Cooke said.
By 2022, those mitigation options will be gone, leaving the state’s farmers in dire straits. They will have other options, such as transfers of water rights from cities, and they also have grandfathered rights to pump groundwater, Buschatzke said.
“But I don’t think anyone expects the ag districts will be able to completely replace their reduced allocations with groundwater,” he said.
Allocations of Colorado River water began with the 1922 Colorado River Compact. That agreement among Arizona, Colorado, Utah, New Mexico, Wyoming, Nevada and California divided the 16 million acre-feet of water among the states.
In 1935, Hoover Dam created Lake Mead, the largest manmade lake in the nation, and launched the era of Colorado River storage and flow regulation. In 1966, the Glen Canyon Dam created Lake Powell in Utah, at the eastern edge of the Grand Canyon, allowing the upper basin states to store their river allocations.
In 1968, Congress authorized the Central Arizona Project, an aggressive plan to carry 1.8 million acre-feet per year of Arizona’s river allocation through Phoenix to southern Arizona. The 336-mile uncovered canal ends in a recharge facility that lets the water sink into the aquifer near Tucson.
Tucson stores its share of the water in the aquifer for pumping to homes and businesses in the city of 900,000 people. Phoenix stores its CAP water in Lake Pleasant, an 11-square-mile reservoir that also serves as a popular boating spot.
A series of meetings over the next few months will determine the exact course of action, but regardless of what happens, households are unlikely to see much impact, Buschatzke said.
“You’re not going to see a request for people in their homes to shower just two times a week. We’re not at that level.”
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