Vanishing reservoir lakes herald America’s future water crisis

The tell-tale signs are high on the cliffs. The red sandstone rock is bleached a whiter shade below a certain level. Just like the rim markings on a bath after the water has drained out.

The rock walls surround Lake Powell on the Arizona/Utah border. The artificial reservoir sits behind a major dam on the Colorado river on which about 40 million people across seven western American states and parts of Mexico rely for their water and some power supplies.

However, Lake Powell and its older sister reservoir, Lake Mead, downstream at the Arizona/Nevada border, are essentially drying up. Not so long ago they were effectively filled to the brim. There were even fears on occasion that Lake Powell would overflow. Now it is at its lowest ever level. Over the past year or so levels in Lake Mead dropped 22ft and 40ft at Lake Powell.

Amid the so-called megadrought – the most intense dry spell across the western United States in an estimated 1,200 years – levels on the Colorado river system, which has been harvested for decades as a source of both water and hydro-electric power, have been declining steadily.

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Farmers and businesses either have already or will in the near future likely experience reduced levels of water. Both groups are likely to have to rethink how they operate.

There is some work under way on potential scientific solutions, an increased use of desalinated ocean water or even cutting edge plans, for example, on cloud seeding aimed at generating more precipitation. However, scientists accept this will not be enough. Conserving water will be essential. And some environmentalists acknowledge this is starting to happen with, for example, the glitzy hotels of Las Vegas becoming pioneers in the recycling of water for their famous fountains.

The ongoing drought has also led to jostling among states for access to water.

Last month, authorities in Nebraska announced plans to invoke an obscure 100-year-old agreement to divert water from a river it shares with Colorado via a new canal. Politicians in Nebraska wanted to get in ahead of projects planned in Colorado which, they feared, could have led to a loss of water to which they felt their state was entitled.

Arguably the more immediate threat from the falling water levels is to electricity generation.

The Glen Canyon Dam at Lake Powell uses the gravitational force of the Colorado river to generate power for nearly six million homes and businesses in the region.

Locals estimate that water levels in parts of Lake Powell have already fallen overall by more than 100ft. If this continues and levels fall by a further 32ft, it will reach what is known technically as minimum power pool elevation. At that point the turbines lose capacity to produce power as they start to take in air along with water and must be shut down before they are damaged. If levels fall further, the reservoir would reach what is known as the “dead pool”, at which point water could no longer pass through the dam by the power of gravity.

The shape of the reservoirs – essentially a “V” which is broader at the top and narrower at the bottom – is exacerbating the problem caused by drought and climate change. As the levels fall, each remaining foot in depth holds less water.

In April at Lake Mead the top of a water intake valve used originally in the 1970s to draw water from its depths appeared for the first time above the surface. Authorities have been forced to use a second intake valve deeper in the reservoir.

At Lake Powell, features have re-emerged that have not been seen in more than 50 years since the desert gorges and canyons were drowned by the flood water after the construction of the dam.

Guides operating boats at Lake Powell told The Irish Times last week of having to circumnavigate rocks protruding from the water which they previously safely motored above. At the famous Antelope Canyon the falling water levels now allow kayakers, paddle boarders and those in small boats to enter the narrow gorge and view the cliffs soaring 150ft or so about the surface. At points in the past, boat passengers were almost at eye level with the top of these same cliffs.

At Lake Mead there are darker stories. As the water levels diminished, in recent weeks human remains have been found – one body was discovered in a barrel – which have generated much speculation about the reservoir being used as a burial ground for victims of mafia killings over the years in Las Vegas about 30 miles away.

Last year falling water levels at Lake Powell exposed a crashed car with a body still inside the vehicle.

In an attempt to deal with the falling levels, US authorities have announced “extraordinary actions” to boost water levels at Lake Powell and to facilitate the continuing operation of power generation.

They are to retain in Lake Powell 480,000 acre-feet of water that was scheduled to flow down the Colorado river through the Grand Canyon and into Lake Mead for use in California, Nevada and Arizona. One acre-foot is just over 325,000 gallons. An additional 500,000 acre-feet is to be released from another dam on the Wyoming-Utah border which will eventually make its way to Lake Powell.

Near Lake Powell sits the small town of Page, Arizona. It owes its history to the Glen Canyon Dam as the location was originally used as an encampment for workers employed on the massive project.

However, the 8,000-plus residents are now seeing the impact of climate change and the megadrought in America’s west at first hand.

Locals say that last year the extensive wild fires in California blanketed the area in smoke and blotted out the arid red sand and rock desert landscape.

About 40 per cent of Page’s energy comes from the nearby hydro-electric power station at the dam. Without its energy, prices could increase by 25-30 per cent, according to some reports.

And then there is the potential implications on tourism. A number of private aircraft including some hugely expensive business jets sit on the tarmac of the city’s small airport. An extensive flotilla of houseboats are berthed at its marina. Some are for rent, others are reserved for use by their owners. However, as the water levels recede, some of the slipways can no longer be used.

Lake Powell is enormous. It is 189 miles long, has a shoreline of about 2,000 miles, longer than the entire US pacific coast. And despite the falling levels, it is still a couple of hundred feet deep in places. It attracts an estimated two million visitors annually.

The water storage system that millions of people across the western United States rely on is dependent on snow pack in the upper Rockies... that storage system is not performing in the way it has in the past

—  Sarah Porter

Sarah Porter, director of the Kyl Center for Water Policy at Arizona State University, says the water levels in the lake are dropping as more water is being taken out of it than is being put into it.

Scientists and environmentalists maintain the source of the problems lies several hundred miles away in the Rocky Mountains.

Porter says the water storage system that millions of people across the western United States rely on is dependent on snow pack in the upper Rockies.

“And what we are really seeing here is that storage system is not performing in the way it has in the past, for various reasons.” She says climate change and drought are very significant causes.

The level of snow and rain falling in the Rockies is broadly in line with yearly averages. However, this is not translating into water making its way into the streams and tributaries that lead to the Colorado river.

“Last year we had 93 per cent of average snowfall but 34 per cent of average inflows into the system. It looks like this year we will have something into the 90s but inflows will be in the 60 per cents of average,” she says.

Porter says snow melt is now different. She says more seems to be going into the atmosphere while more dust on the snow appears to make it melt faster.

“We also think that when it is hotter the ground is losing more moisture, so when the ground has a chance, it holds on to the snow melt.”

Kevin Moran, associate vice-president for regional affairs at the non-profit Environmental Defense Fund who has been working on water issues in the southwest for six years, says actual flows on the Colorado river have declined by 20 per cent since 2000.

He says scientists attribute about half of the decline to a warming climate.

And he fears the situation could get worse.

Moran tells The Irish Times future projections are bleak unless action is taken to cut methane and carbon dioxide emissions.

“The scientists tell us we must plan for a river that may have 15-20 per cent less flow than today – a further 15-20 per cent. Hopefully it will not be that bad and we can mitigate further drying by bold action on climate.

“We built the two biggest reservoirs in North America and built canals to serve Phoenix [in Arizona] and gotten whatever reliability and security we are going to get from pipes and dams. And now we have to think about the health of watersheds, the eco system and the river itself, otherwise we go down a negative spiral.

“We have to plan for the river we are going to have, not the one we remember or wish for.

“We need to invest in the health of forests and watersheds and use new approaches on a big scale like nature-based solutions, the ability of nature to filter, cleanse and store water in a natural system,” he says.

Moran says conservation is going to be key to dealing with the declining levels of water. He says some cities in the region have done a really good job in decoupling population growth from water use. There is also evidence of new thinking on the part of business and agriculture.

“I would definitely commend Las Vegas; the land of glitzy fountains is a leader in recycling water and in doing measures and regulations in neighbourhoods to reduce water use. They have made it uncool to water grass.”

He says “non-functional turf“ or ornamental grass will be phased out over the next five years.

Moran says that, historically, rights to water was based on a system of “seniority” – those with the oldest rights had priority. The general mindset was “hands off my water”. However, he says new thinking is emerging on how to deal with a reality that the river may not in future be able to generate the levels set out in deals signed in the past.

He says some farmers may lose up to 40 per cent of the water they were used to receiving and are examining the potential of crop switching. He says one group is working with a major tyre company on growing an America desert shrub called guayule, which is a natural source of rubber. He says it uses about 40 per cent of the level of water needed by some traditional crops.

Porter says 70-75 per cent of water withdrawn from the Colorado river system is used for agriculture and about 20-25 per cent for cities.

“Every single city that uses Colorado river water is facing challenges of water resilience but every city for the most part has a plan.

“In central Arizona about 93 per cent of water that enters the wastewater treatment system is treated and retained. Some of it is sent to cool nuclear power plants and some is used to water golf courses.

“At present none [of the treated recycled waste water] is being sent to the drinking water treatment system but that is in our future and is already happening in southern California.”

She says this year is the first time that farmers faced shortages in their expected level of water from the Colorado river. She says, in response, some farmers are reducing the amount of acreage that is in production and others are using ground water and other supplies to make up the losses. However, she says using ground water is not sustainable.

Porter says there are “little tiny things” that science can do to try deal with the water shortage but in reality “we don’t have much control over Mother Nature”.

She says desalinating sea water produces very expensive water and may make sense for cities. She says there is a large desalination plant in southern California. Using desalinated sea water for farming would make food very expensive.

“Arizona is looking at a bi-national desalination plant with Mexico. Arizona water users would finance the building and operation of the plant and taking in exchange some of Mexico’s Colorado river water.”

Porter says there are some studies being undertaken into cloud seeding to try generate more snow or rain.

“This may have a small impact on snow cap, maybe 5 per cent more precipitation but we can take everything we can get. However, no one is looking at that as the main response.

“The response has to be; there is less water, we have to use less water.”