Torrents of water have been rushing through bypass tubes on either side of Glen Canyon Dam on the Colorado River since Monday, sending large volumes of habitat-replenishing sediment downstream into the Grand Canyon.

Interior Secretary Ken Salazar on Monday opened the river outlet tubes, and over the course of the week, water volumes will gradually increase, peaking at 42,300 cubic feet per second.

The high-flow experiment -- the first since 2008 -- takes advantage of sediment deposited since late July by the Paria River, a tributary of the Colorado River. Scientists estimate it has deposited approximately 500,000 metric tons of sediment -- enough to fill a football field 230 feet deep.

"This is truly an historic milestone for the Colorado River, Grand Canyon National Park and the United States Bureau of Reclamation," Salazar said Monday. "It was an honor to open the door to a new era for Glen Canyon Dam operations and the ecology of Glen Canyon National Recreation Area and Grand Canyon National Park -- 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 high-flow experiment, which will continue through Friday, is the fourth such test in 16 years and the first at Glen Canyon Dam under a new experimental long-term plan Interior unveiled in May.

As part of the new plan, Bureau of Reclamation officials will schedule high-flow releases when the conditions are right to maximize ecosystem benefits along the Colorado River corridor -- typically after major storms that have flushed sediment into the system. The experimental releases, which will continue through 2020, will send sediment downstream to rebuild sand bars, beaches and backwaters. The rebuilt areas will provide key wildlife habitat, enhance the aquatic food base, protect archaeological sites and create additional camping opportunities in the canyon.

"Favorable sediment conditions in the system only occur periodically, so the ability to respond quickly and make the best use of those deposits when the time is right is essential," said Anne Castle, assistant secretary of the Interior for water and science.

The temporary high-flow tests will improve downstream resources without compromising water and power needs during the weeklong run, Salazar said. Scientists from the U.S. Geological Survey and other agencies and universities will monitor the flows and collect data to determine how the experiment is affecting the canyon.

Those data will be used to fine-tune the next experimental flow. The protocol adopted last spring allows for "adaptive management" -- essentially adjusting as necessary based on what scientists learn from one experiment to the next.

"This new protocol developed by Reclamation will protect both the Grand Canyon and the delivery of water for communities, agriculture and industry," Salazar said. "We are taking a practical approach. If, for any reason, the new high-flow experiments do not yield the positive results we anticipate, we have the ability to change and adjust future flows."

The Colorado River, which once roared through its channel during heavy rains, is now regulated by a series of dams built in the early part of the 20th century. Glen Canyon Dam, constructed in the 1960s, is one of the largest. Millions of people rely on the river for water, hydropower and agricultural production, but construction of the dams has starved the Grand Canyon of sediment, harming habitat.

Environmental and recreation groups celebrated the new experimental flow.

"The water released this week is the first in a long-term plan that will help to build new camping beaches in the Grand Canyon, and ultimately will improve the canyon experience for boaters supporting a $26 billion recreation economy that depends on the Colorado River," said George Wendt, president of OARS Outdoor Adventure River Specialists and a member of Protect the Flows, an environmental group. "This release shows an attempt at good stewardship of the area and is an example of how the conservation community and those who love to recreate on the river worked together with the Department of Interior on a solution that both fish and rafters will benefit from for years to come."