From the Waterloo International Airport Website:
“Effective June 1, 2009 Delta / Northwest Airlines service from the Region of Waterloo International Airport (YKF) will be suspended.
If you are booked on a flight, departing from the Region of Waterloo International Airport after the June 1, 2009 suspension date please contact Delta / Northwest Airlines customer service line at 1-800-225-2525 or your travel agent to make alternative travel arrangements or arrange for a refund.”