The federal government on Tuesday laid out options for saving the Colorado River in an effort to prevent it from falling to critically low levels and put an end to months-long negotiations between the seven western states and Indigenous nations that rely on it as a dwindling resource.
As less and less water has been flowing through the river and its reservoirs fell to historic lows, the US Bureau of Reclamation, which manages water resources, called on the basin’s seven states – California, Arizona, Nevada, New Mexico, Colorado, Utah and Wyoming – to find ways to cut as much as 30% of their river water allocation.
But despite numerous deadlines, the states have been unable to agree on how to reduce their usage to prevent deadpool – the point at which the waterline sits beneath intake pipes at the Hoover Dam and the river effectively ceases to flow. Last year, the Lake Mead reservoir sank to its lowest level since the 1930s.
On Tuesday, the Department of the Interior said it would either impose cuts to water allotments according to the water-rights priority system or evenly across the board.
The interior department did not say how states should reduce water usage, but defended its authority to make sure basic needs such as drinking water and hydropower generated from the river are met – even if it means setting aside the priority system. The more than a century old method of dividing up the water is based on a senior priority system among the states – basically, whichever one was there first – that puts California at the front of the line.
The 1,450-mile (2,334km) Colorado River serves 40 million people and generates hydroelectric power for regional markets, and irrigates nearly 6m acres (2.4m hectares) of farmland.
California receives the largest share of water from the Colorado River and would be most affected by an overall cut, particularly its agricultural regions, which help feed the country.
If allotments are changed based on the seniority of water rights, California, as the oldest user of the river’s water, would mostly be spared, but it could be disastrous for Arizona, causing the aqueduct that carries drinking water to Phoenix and Tucson to be reduced to nearly nothing and hurting the Native American tribes that rely on that water, and whose rights to it are guaranteed by treaty.
Among the main differences between the two plans is whether states should account for the vast amount of water lost along the Colorado River basin to evaporation and leaky infrastructure as it flows through the region’s behemoth dams and waterways.
Federal officials say more than 10% of river water evaporates, leaks and spills – yet Arizona, California and Nevada have never accounted for that loss.
California disagreed with that approach on grounds that the state would lose a significant amount of water if such losses were counted. The further south the river travels, more water evaporates – meaning that if evaporation losses were counted, California and Arizona would stand to lose more than states further north.
Tommy Beaudreau, the interior deputy secretary, told the New York Times he would rather see the states that rely on the Colorado River reach an agreement among themselves, so that the federal government doesn’t have to impose reductions.
The lengthy environmental analysis released by the Biden administration on Tuesday explores both options, as well as a third option that includes taking no action. States, tribes and other water users now have until 30 May to comment before federal officials announce their formal decision.
Beaudreau gave no indication of whether the department prefers one approach over the other.