The Centennial Fountain, completed in 1989, commemorates the 100th anniversary of the Metropolitan Water Reclamation District of Chicago. The fountain is located near the very spot where the agency reversed the flow of the Chicago River back in 1900.
Centennial Fountain is comprised of two major parts. The first is the semicircular waterfall that runs every day between Memorial Day (last Monday of May) and Labor Day (first Monday in September) from 8 a.m. until 11 p.m. The second part is a water cannon that shoots a huge arc of water across the Chicago River for 10 minutes at the top of every hour (beginning at 10 a.m., except the hours of 3 p.m. and 4 p.m.). Boats that are traveling down the river at these times either pause and wait for the cannon to stop, or they will go right on through and get soaked by the sheet of water that cascades from the arc.