A controlled flood that replenishes Grand Canyon beaches will not happen this year as authorities grapple with the effects of a two-decade drought on the Colorado River.
It is a decision that shows how the lack of water has forced the federal government to modify operations on the river.
“This is a microcosm of a much larger problem and it shows that less water means changing management practices, which in the long term will likely have negative effects on the environment and the public interest. in general, “said Kyle Roerink, executive director of the Great Basin Water System.
Eight times since 1996, the US Bureau of Reclamation has released a dramatic surge of water from the Glen Canyon Dam to break up the sand from the river below and redistribute it downstream.
The discharges primarily benefit recreational users of Marble Canyon and the Grand Canyon by repairing and expanding beaches.
But this year, despite favorable sedimentary conditions, the federal government decided to withhold the flow.
Lee Traynham, program manager for the office, said his agency used a process to determine whether unacceptable negative effects would come from a flood experience.
“And in that case, this year we determined there would be,” she said.
Authorities do not even consider discharging until hundreds of thousands of tonnes of sediment, mostly from the Paria River, accumulates in the Colorado River in northern Arizona.
Now more than a million tonnes of sediment has accumulated in the river, Traynham said.
“Since we have been carrying out (the controlled flooding) this may be the second largest contribution of sediment that we have seen,” she said.
But assessing sediment buildup is only the first part of the process.
Whenever a discharge is considered, state and federal officials meet to assess the potential effects on other elements, such as water quality, tribal concerns, a federally protected fish species, electricity production and the status of a fund made up of income from electricity production. .
This year, supporters of the flow release feared that persistent drought conditions would limit the ability to conduct an experiment in the future. They also argued that sediment redistribution was necessary because the last flooding occurred in 2018.
Joel Sankey, acting head of the US Geological Survey’s Grand Canyon Monitoring and Research Center, said beaches downstream are eroding over time.
This year, the monsoon rains runoff also passed through some beaches, damaging them, he said.
“Some of them are in a particularly rough condition because of it,” Sankey said.
Protect the tampon
But the majority of the team that considered flooding this year found the effects on other resources unacceptable.
A 60-hour flow, which would have started on Monday, would have reduced Lake Powell’s elevation by about two feet.
The decrease runs counter to a measure taken last summer by the Bureau of Reclamation to increase the lake’s elevation by three feet by releasing water from reservoirs upstream, the office wrote in a letter announcing the decision not to conduct a debit experiment.
Water from the reservoirs upstream is believed to help Lake Powell avoid plunging below an elevation of 3,525 feet. (The lake level is measured in elevation, not in depth. An elevation of 3,525 feet means the water level is so high above sea level.)
An elevation of 3,525 feet provides a buffer zone of 35 feet from the minimum water level that allows the Glen Canyon Dam to generate electricity.
Officials are also concerned about other potential effects of dropping below this level, such as the release of warmer water, the release of low-oxygen water, and the risk of non-native fish. cross the dam and flow into the river below, Traynham said.
Releasing a stream of water to break up the sand could reduce support for future discharges upstream into Lake Powell, which will likely be necessary, according to the letter from the office.
Water level projections show Lake Powell temporarily dropping below the target elevation next year.
“Any extra time we spend below 3,525 is considered very risky,” Traynham said.
Conducting a flood would leave the reservoir below that altitude for an additional 15 days, according to the letter.
Decrease in electricity production, increase in expenses
Simulated floods do not affect the total volume of water discharged downstream in a year. To compensate for the drop in lake level due to the temporary precipitation of water, the dam would reduce its discharges over the following months.
But these reduced discharges would put even more pressure on electricity production, which is already suffering from falling lake levels and a mandatory reduction in downstream discharges.
The Western Area Power Administration, a government agency that markets and transmits wholesale electricity, is already unable to meet demand.
“To fill the deficit, (the administration) must buy energy from the wholesale market to meet these obligations,” said Peter Soeth, a spokesperson for the administration.
Reduced electricity production means less money for a fund that pays for things like dam maintenance and environmental programs. The Bureau of Reclamation and the Western Area Power Administration are already postponing maintenance and considering rate increases to offset the currently expected decline in the fund.
A controlled flood would force the administration to purchase even more electricity to meet demand, costing the fund between $ 1.3 million and $ 3 million, according to the Bureau of Reclamation.
The decision is criticized
This isn’t the first time the Bureau of Reclamation has decided not to flood after the river has reached its sediment build-up trigger.
In 2015, office officials called off the flooding because they were trying to stop the spread of a non-native fish, according to Jack Schmidt, director of the Center for Colorado River Studies at Utah State University.
The existing framework for the implementation of controlled flooding is supposed to put decision-making in the hands of science and environmental management, not politics, he said.
“This is the first time that a flood has been canceled because of politics, income and the economy and it is a dangerous precedent,” he said. “This is exactly what was not supposed to happen.”
He said estimates of the costs of holding a flood this year are consistent with estimates from previous years when flooding was carried out, but the bureau said this year’s costs appear in a different context.
The Bureau of Reclamation says authorities are using the best scientific data available and examining the condition of all resources before making a decision on whether to proceed with a flood.
Schmidt, a member of the original team that called for controlled flooding in the 1990s, is hoping the Bureau of Reclamation will release in the spring, which the bureau says it will consider.
John Weisheit, Colorado River guide and longtime advocate, said there was no reason not to release the flow this fall. He said the releases do not mean hydropower production will cease.
“Here’s what it means,” he said. “The Grand Canyon is not important. Our net budget is bigger than the Grand Canyon.