From PR.com:
The Colorado River reached its peak flow for 2009 in Utah’s Cataract Canyon on May 26. The river was flowing at a raging 52,000 cfs(ft^3/s). Cataract Canyon is known for it’s exciting rapids and “when the river reaches flows over 50,000 cfs the rapids are awe inspiring” says veteran rafting guide Walker Mackay. The Rapids known as the “Big Drops” are so large that the National Park Service sets up a river rescue camp below the rapids when the river reaches the 50,000 cfs mark.