Torrential rains in California | The reservoirs are filling up, but the situation remains fragile

Torrential rains in California since the start of the year have filled the state’s water reservoirs. But reserve management remains fragile throughout the American Southwest, where the low level of the Colorado River has remained virtually unchanged.

The 12 atmospheric rivers that have hit the California coast since the start of 2023 have filled several large water reservoirs in the northern and central parts of the state. A glance at the California water resources map shows that current levels at Oroville, Shasta, New Bullards, Don Pedro, Camanche and other reservoirs are above their historical average.¹.

Faced with this resurgence, Democratic Governor Gavin Newsom announced, on March 24, relaxations in the restrictions on water consumption.

But we must remain very cautious in the face of this good news. Because they come with some bad sides, explains Amir Aghakouchak, associate professor at the Center for Hydrometeorology and Remote Sensing at the University of California at Irvine.

According to Mr. Aghakouchak, this very contrasting phenomenon could repeat itself in closer sequences in the future. “In 2017, we experienced the same situation: a five-year drought suddenly stopped by major floods. We have to be prepared for more sudden changes. We cannot assume that we will experience long periods of calm. »

In the Salinas Valley, an area halfway between San Jose and Monterrey, the rain did cause significant flooding. The damage to agricultural land is considerable. The price of lettuce, grown in abundance in this region, should increase shortly and remain high for months.

Strawberry fields were also affected.

“From north to south, wildlife, farmers and farm workers have not been spared,” confirms Chris Lopez, Monterey County Supervisor where the Salinas Valley is located. People’s jobs are affected. »

Little impact on the Colorado River

Another issue that should not be overlooked is the impact of recent rains on California’s groundwater levels. According to Alexis Maximilien Berg, assistant professor in the geography department of the University of Montreal, a winter of heavy rains will not succeed in raising them.

Recent rains have failed to raise the level of the Colorado River, which remains desperately low, as The Press reported it on 1^er February 2023². Levels of the two largest reservoirs in this river, Lakes Mead, in Nevada east of Las Vegas, and Powell, on the Utah-Arizona border, have risen a little over the past few years. last weeks. But they remain far from the average.

“Sometimes atmospheric rivers, after pouring most of their water over California, also leave water in Colorado basins. But not this time. The drought continues,” observes Amir Aghakouchak.

“If nothing is done, Lakes Mead and Powell could become what are called ‘dead pools’,” says Alexis Maximilien Berg. Initially, the power stations of the dams will no longer be able to produce electricity. In a second step, the water will no longer come out of them. »

The river’s water level is so low that the seven states that partly depend on it have been ordered by the federal government to come up with a plan to reduce their consumption – it was to be presented no later than January 31. However, there was no agreement because California, the largest consumer, refuses to join the agreement signed by the six other states. The project is still on hold.

With The Canadian Press and East Bay Times