Sandy beaches have reappeared more than 100 miles (160 kilometers) downstream of Glen Canyon Dam, an early measure of success for a massive flood last week designed to rebuild habitat along the Colorado River in the iconic Grand Canyon.

However, it will be weeks before scientists know whether the six days of high flows realized the Department of the Interior's goals of moving more than 500,000 metric tons of sediment down the canyon.

"Surely there are new white sandbars in a lot of places, but what we have learned from doing this in the past is that the devil is in the details," said Jack Schmidt, chief of the U.S. Geological Survey's Grand Canyon Monitoring Center. Test floods in 1996, 2004 and 2008 had some unintended consequences, such as increasing the population of predatory non-native trout.

Initial tests The department ordered the flood, released in a gush from the Glen Canyon Dam starting Nov. 19, to help create beaches and back eddies for campers, rafters and native fish. Since the dam was built in 1966, the only sediment sources for the Grand Canyon are the naturally flowing Little Colorado and Paria rivers, which feed into the Colorado River below the dam. A popular tourist destination, the canyon's beaches and wildlife depend on sand and mud carried by the Colorado River.

USGS researchers spent the Thanksgiving holiday camped along the river monitoring the flood, Schmidt said. Their samples will help determine if the floodwaters actually moved suspended sediment downriver, among other tests, he said.

A group from the National Park Service and the USGS left Monday to float downriver and download before-and-after images from cameras mounted in the canyon and collect additional samples. A preliminary report on the flood's aftermath will be presented at a stakeholders meeting in January 2013. [Related: The Grand Canyon in Pictures ]

"Now starts the hard work of figuring out and understanding the nature of the process that went on during the flood and the environmental impact of the flood," Schmidt told OurAmazingPlanet.

First new beaches National Park staff at Phantom Ranch, a Colorado River crossing with cabins and a campground more than 100 miles (160 km) downstream of the dam, reported new sand at two nearby beaches, said Jan Balsom, deputy chief of science and resource management for Grand Canyon National Park. Roy's Beach, on river right just upstream of Phantom Ranch, has sand for the first time in a number of years, she said. Cremation Camp, a rafter camp upstream on river left, also has new beach sand.

Science news from NBCNews.com

Genetic testing confirms the legendary Bigfoot is a human relative that arose some 15,000 years ago at least according to a press release issued by a company called DNA Diagnostics detailing supposed work by a Texas veterinarian.

Read the rest here:

Beaches back after Grand Canyon floods