Thu July 5, 2012
Simulated Floods Designed To Mitigate Dam Impacts
The Colorado River is about to run wild again, at least a couple times a year. In May, Interior Secretary Ken Salazar approved a series of simulated floods -- releasing huge amounts of water and sediment from the Glen Canyon Dam over the next several years. It’s all part of a long-studied effort to restore the river environment downstream.
Five boats recently launched a two-week Grand Canyon river trip. The group of tourists paddled white-water rapids, hiked side canyons and camped at river’s edge.
But vast sandy beaches ideal for camping are scarce these days.
Before the dam was built 50 years ago to store drinking water and harness hydropower for western states, the silt-laden Colorado River flowed high through the Grand Canyon, creating sandy beaches along the shore.
Longtime river guide Brad Dimmock said sediment is now blocked behind the dam so some of those beaches have turned rocky and some are overgrown with shrubs and trees.
"The vegetation is on a rampage and it’s taking over beaches at a pretty high rate of speed to where it’s kind of a war between us and the vegetation at some camps," Dimmock said.
Currently there are fluctuating flows coming from Glen Canyon.
"Flows that go up and down in a dramatic fashion in a 24 hour period," said Nicolai Lash, spokesman for Grand Canyon Trust, a conservation group. "This is done for generating as much hydropower revenue as possible."
Unfortunately, Lash said, it’s counterproductive for the resources in Grand Canyon, like the beaches and an endangered native fish.
Matt Kaplinski is a geologist who was once part of an ad hoc group of scientists, river guides, tribes, power companies and others who make recommendations to the federal government on how to improve the river environment.
"It’s like the Doctor Strangelove movie: how I quit worrying and learned to live with the dam," Kaplinski said. "That’s the premise of the program, is to see how we can operate this dam and balance the needs of water storage and power delivery with environmental conservation downstream."
The best solution they’ve come up with are these high flows. Dam managers wait until sediment accumulates upstream, then they release a large amount of water in hopes of pushing sediment downstream onto beaches. So far the federal government has allowed three high flows in the last 16 years -- 1996, 2004 and 2008.
But this year they’ve decided to accelerate the high flow program -- authorizing as many as two floods a year for the next eight years. And it hasn’t come without controversy. Electric companies don’t want to see water bypass the hydroelectric turbines. The 2008 flow cost them $3.8 million in lost hydropower revenue.
But river guide Brad Dimmock said allowing these high flows is the government’s responsibility to the Grand Canyon.
"Once you come in and take away the sediment flow or you alter the environment tremendously, and you have your fingers on the controls of the dam, you are technically God," Dimmock said. "I mean you decide how that ecosystem is going to mature you become nature to a large part."
The problem is nature is often at odds with the needs of the western population. Scientists will continue to study the impact of these high flows, balancing electricity and water demands with the mandate to protect and preserve the critical river environment.
KNAU and Arizona News
KNAU and Arizona News