NEW YORK - (AP) - Engineers have begun testing the waterfalls forthe Sept. 11 memorial at ground zero in Manhattan.

The cascades are the largest man-made waterfalls in NorthAmerica. They empty into massive reflecting pools that mark spotswhere the footprints of the World Trade Center towers once stood.

Testing of the waterfalls for the north pool began for the firsttime at the site at about 11 a.m. Tuesday. The tests includedswitching on the eight pumps to see how the water will flow intothe basin.

More than 350,000 gallons of water streamed into the pool,circulating at a rate of 52,000 gallons per minute.

Testing of the south pool waterfall will begin next spring.

The 176-foot-perimeter pools are the centerpiece of MichaelArad's "Reflecting Absence" memorial.