PAGE, Ariz. (AP) -- Authorities launched an experiment Monday aimed at building beaches and sandbars on the Colorado River through the Grand Canyon in northern Arizona.
Interior Secretary Ken Salazar opened the river outlet tubes at noon and called it "an historic milestone" and "a new era in which we realize that the goals of water storage, delivery and hydropower production are compatible with improving and protecting the resources of the Colorado River."
The peak flow will last 24 hours from Monday night into Tuesday, and the river will run high for five days.
The heavy rush of water down the river at Glen Canyon Dam is part of a government program to restore the Grand Canyon's ecosystem.
The goal is to wash millions of tons of sediment downstream to create beaches and improve habitat for plants and animals, and protect archaeological sites.
Grand Canyon National Park officials have contacted visitors with backcountry or river permits and advised them to camp on high ground this week, according to The Arizona Republic.
The experiment that could hurt next year's fishing - and complicate hydropower production and water storage - in the name of a more environmentally correct river.
The rush of water churning up sand for new beaches and backwater sandbars was welcomed by many environmentalists and park managers. It's the fourth experimental flush since 1996, and the first since Salazar in May decreed them routine in a 10-year protocol that, weather permitting, could mean mini-floods every year.
"This is a great victory," said Nikolai Lash, program director with the Grand Canyon Trust.
Previous experiments in 1996, 2004 and 2008 were one-time fact-finding missions instead of fundamental shifts in river management.
"This (Obama) administration can be patted on the back and thanked for doing what we've been trying to do, seriously, for 15 years," Lash added.
The previous experiments yielded mixed results, partly because a return to up-and-down flows timed partly to regional summer hydropower needs wiped out many of the new beaches and sandbars.
Advocates hope the effects will be longer lasting if these floods come more regularly and if a longer-term Interior Department planning effort leads to steadier flows through the summers.
But critics say there's little environmental benefit and that it comes at a cost.
In comments submitted to the Interior Department before the decision to go forward with regular flushes, the Colorado River Energy Distributors Association, a group of non-profit energy utilities, noted that previous springtime flood experiments helped boost the population of non-native trout that feed on the endangered humpback chub.
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