Drought limits water supply for western US agriculture

Drought in the western US is limiting water availability for agriculture in 2022, spurring cuts to allocations in California and Arizona as extreme dryness continues into a third year.

The US Bureau of Reclamation announced last month that irrigation districts accounting for farmers across California's Central Valley would receive a zero-water allocation from the Central Valley Project as early-year dryness weighs on anticipated water supply. No water is allocated for irrigation north and south of the Sacramento-San Joaquin river delta, including off the Sacramento river, according to the 23 February announcement. Additional allocations will be announced in May.

The Central Valley Project spans from the Cascade mountain range to Kern River in southern California, distributing about 5mn acre-feet (enough water to cover one acre of land to a depth of 1ft) of water for irrigating one-third of the state's agricultural land.

But water reserves in major regional reservoirs continues to decline from historical levels, and total storage for the northern Central Valley Project averaged 60pc of the 15-year average as of yesterday, according to the agency.

The entirety of California remains in at least moderate drought, according to the US Department of Agriculture (USDA) drought monitor. Snowpack in the Sierra Nevada, a key determinant of the state's water supply, neared 15 inches by the end of February — less than two-thirds of the typical amount by that time, the USDA said.

Meanwhile, the California Department of Water Resources cited record dryness in January and February, compared to the same period in prior years. The Sierra Nevada snowpack statewide was 63pc of average by the beginning of March, bringing statewide snowmelt forecasts to 66pc of average in tandem with below-normal precipitation.

Increasingly scarce water supply in the western US is also poised to be a key factor in Arizona planting decisions this season as water levels continue to decline in the Colorado River Basin. Lake Powell will soon decline below 3,525ft — the lake's target elevation — following abnormal dryness from January-February, although water elevation is expected to recover during the spring runoff season, according to a 4 March release from the Bureau of Reclamation. Falling water levels on Lake Mead have triggered a Level 1 Shortage Condition, reducing water allocations to Arizona by about 18pc, according to the bureau.

By Jasmine Davis