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America’s largest reservoirs are heading in the right direction, scientists say


ALBUQUERQUE, NM – Parts of California are under water, the Rocky Mountains are bracing for more snow, flood warnings are in place in Nevada and water is being released from some reservoirs in Arizona to make way for the expected abundant spring runoff.

All the moisture helped ease the drought conditions in many parts of the western United States. Even the main reservoirs of the Colorado River are moving in the right direction.

But climate experts warn favorable drought maps are just a blot on the radar as the long-term effects of persistent drought linger.

Groundwater and reservoir storage levels – which are taking much longer to rebound – remain at historic lows. It could be more than a year before the extra moisture has an effect on the Lake Mead shoreline that straddles Arizona and Nevada. And water managers are unlikely to have enough leeway to turn back the clock on proposals to limit water use.

Indeed, water release and retention operations for the massive reservoir and its upstream sibling – Lake Powell on the Utah-Arizona border – are already set for the year. The reservoirs are used to manage water deliveries from the Colorado River to 40 million people in seven US states and Mexico.

Still, Lake Powell could gain 14 meters (45 feet) as snow melts and enters tributaries and rivers over the next three months. Its rise will depend on soil moisture levels, future precipitation, temperatures, and evaporation losses.

“We’re definitely heading in the right direction, but we still have a long way to go,” said Paul Miller, hydrologist at the National Weather Service’s Colorado Basin River Forecast Center.

Federal forecasters are due to release temperature, precipitation and drought forecasts for the next three months on Thursday, as well as the risk of spring flooding.

California has already been inundated with a fire hose of moisture from the Pacific Ocean that has caused flooding, landslides and toppled trees.

Ski resorts on the California-Nevada border are marking their snowiest winter time since 1971, when record keeping began. In fact, the Sierra Nevada is on course to surpass the second-highest snowfall total for an entire winter season, with at least two more months to go.

In Arizona, forecasters have warned that heavy rain is expected to fall on snowpack that has started in the mountains above the desert enclave of Sedona. One of the main streams running through the tourist town was expected to reach flood stage and evacuations were ordered for some neighborhoods on Wednesday evening.

“We’ve pretty much passed all kinds of averages and normals in the lower Colorado basin,” Miller said, much like other western basins.

Forecasters say the real star has been the Great Basin, which stretches from the Sierra Nevada to the Wasatch Mountains in Utah. It has recorded more snow this season than the past two seasons combined. Joel Lisonbee of the National Integrated Drought Information System said that was remarkable given that in the past decade only two years – 2017 and 2019 – had above-median snowpack.

Overall, the West has been drier than wetter for more than 20 years, and many areas will still feel the consequences.

An emergency declaration in Oregon warns of higher risks of water shortages and wildfires in the central part of the state. Pockets of central Utah, southeastern Colorado and eastern New Mexico still face extreme drought, while parts of Texas and the Midwest have become drier.

Forecasters are expecting hot, dry weather over the next few weeks, meaning the drought will keep its grip in some areas and tighten its grip elsewhere.

Tony Caligiuri, president of the Colorado Open Lands preservation group, said all the recent rainfall isn’t expected to derail groundwater recharge work.

“The problem or danger in these episodic wet year events is that it can reduce the sense of urgency to address longer-term issues of water use and water conservation” , did he declare.

The group is experimenting in the San Luis Valley in southern Colorado, at the source of the Rio Grande. One of the longest rivers in North America, the Rio Grande and its reservoirs have struggled due to low snowpack, long-term drought, and constant demands. It dried up over the summer in Albuquerque and managers had no extra water to supplement the flows.

Colorado Open Lands has reached an agreement with a farmer to withdraw his land and stop irrigating the approximately 1,000 acres. Caligiuri said the idea is to remove much of the chaff from the aquifer, which will allow savings to support other farms in the district so they no longer face the threat of having to shut down their wells. .

“We’ve seen where we can have several good years in place like the San Luis Valley in terms of rainfall or snowpack, and then a year of drought can wipe out a decade of progress,” he said. declared. “So you can’t put your head in the sand just because you have a good wet year.”

Joanna Swanson

Joanna Swanson is Europe correspondent at the Thomson Reuters Foundation based in Brussels covering politics, culture, business, climate change, society, economies and inclusive tech. With specific focus in breaking news, she has covered some of the world's most significant stories.