Rains Not Enough to Recharge Colorado River, or California’s Groundwater

January 31, 2023

New Scientist (paywall):

The three years since 2020 have been the driest in California in more than a century, with 35 per cent of the state under extreme drought conditions and more than 80 per cent under severe drought conditions by mid-December, according to the National Integrated Drought Information System (NIDIS).

With the storms finished as of 19 January, no part of the state was under extreme drought and the portion under severe drought had shrunk in half, according to the NIDIS. Nearly all of the state remained under moderate drought conditions, however.

Jeanine Jones at the California Department of Water Resources says the NIDIS classification system is based on non-irrigated Midwestern agriculture so doesn’t accurately reflect California’s heavily managed water system or snowpack. But she says the storms have improved drought conditions, with total precipitation this year now up to 167 per cent of the annual average.

That water has brought the majority of the state’s major water supply reservoirs above average for this time of year, though these are kept around half full for flood control purposes during the current wet season. At three California reservoirs, managers are testing ways to rely on improved weather forecasts to safely store more water, says Jones.

The storms also left behind a mammoth snowpack already around a quarter larger than the average high point usually seen in April, though the amount of snow that will become runoff depends on a variety of factors such as the dryness of soil and the weather in 2023, says Jones.

Still, “from a surface water perspective, things are going to be good”, says Abatzoglou. “We’re not going to have a surface water drought this year in California.”

Things are more complicated when it comes to the state’s groundwater, which has seen huge losses from a combination of drought and a century of over-pumping. “One year, no matter how wet, is not going to recharge those groundwater basins,” says Jones.

There are numerous projects underway to capture more water from storms to recharge those aquifers, but even large-scale improvements probably won’t be enough to stop some farmland from being taken out of production to balance groundwater budgets, as has been mandated by the state, says Daniel Mountjoy at Sustainable Conservation, an environmental nonprofit in San Francisco.

And even with the recent deluge, California remains set to cut the water it gets from the Colorado river, which has been depleted to record low levels due to a megadrought in the US Southwest. Less affected by the atmospheric rivers, the Colorado river basin has still seen above average snow recently, but it is nowhere near enough to fill extremely low reservoirs along the river, says Jones. “That is literally the proverbial drop in the bucket.”

While rains and snow have helped California quite a bit, water levels are still critical in the Colorado River basin, which supports 40 million people in the Southwest.


Lake Mead’s water levels have continued to rise very slightly over the past week, but the projections for 2023 still look dire.

The reservoir formed by the Hoover Dam on the Colorado River has water levels standing at 1,045.99 feet as of January 24. That’s a slight rise from the 1044.69 feet recorded at the beginning of January.

The increase is likely due to the weeks of heavy rainfall that swept across California and Nevada in recent weeks. The storms came during one of the severest droughts the region has ever seen, and since 2000, most of the western United States has suffered as a result.

Los Angeles Times:

The seven states that depend on the Colorado River have failed to meet a Tuesday deadline for agreeing on a water-use reduction plan, raising the likelihood of more friction as the West grapples with how to manage the shrinking river.

In a bid to influence federal officials after contentious negotiations reached an impasse, six of the seven states submitted a last-minute proposal outlining possible cuts to help prevent reservoirs from falling to dangerously low levels, presenting a unified front while leaving out California, which uses the single largest share of the river.

Arizona, Colorado, Nevada, New Mexico, Utah and Wyoming called their plan a “consensus-based modeling alternative” that could serve as a framework for negotiating a solution. The U.S. Bureau of Reclamation had set an end-of-January deadline for the seven states to reach a consensus. But California officials opposed making evaporation and other water losses in the river’s Lower Basin part of the calculation, as the change would would translate to bigger supply cuts for the state.

In announcing the proposal Monday, Tom Buschatzke, director of the Arizona Department of Water Resources, called it a key step in the “ongoing dialogue” among the seven states “as we continue to seek a collaborative solution to stabilize the Colorado River system.”

John Entsminger, general manager of the Southern Nevada Water Authority, said that “while our goal remains achieving a seven-state agreement, developing and submitting this consensus-based alternative is a positive step forward” as federal officials carry out an expedited review to revise the current rules for dealing with the shortage.

Federal officials told the region’s water managers at a mid-December conference that they would weigh immediate options to protect water levels in depleted reservoirs this year, and that the region must be prepared for the river to permanently yield less water because of climate change.


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