via AZ Republic on October 12, 2011.

Salt River Project opened the spillways at Roosevelt Dam on Tuesday morning, creating a rare spectacle of water gushing into the upper Salt River about 100 miles northeast of Phoenix.

SRP tests the two spillways periodically to make sure they will operate properly in case of a flood.

Tuesday's test was the first time both spillways had been open at the same time since the dam was expanded in 1996. At the peak of the hourlong test, about 100,000 gallons a second poured through 3-foot openings in the spillways.

Among a small crowd of onlookers, Emily Helms of nearby Tonto Basin took pictures during the test. Her husband, Larry Helms, was part of the 1996 expansion project, which made the century-old structure safer in case of flooding.

The water was captured in downstream reservoirs, starting with Apache Lake, and will flow into the canals that deliver water across the Valley.

Here's a video from September 2010 showing the release of water from one spillway.