From Phish's official Facebook page:
Due to insurmountable transportation and public safety issues resulting from the power outage in Toronto after severe downpours in the city, Phish's performance tonight at Molson Canadian Amphitheare has been postponed. The show has been moved to Monday, July 22. All tickets will be honored at the new date. Refunds are available at point of purchase for fans who cannot attend. Phish has been greatly looking forward to their first Toronto appearance in nearly 13 years. Everyone involved worked tirelessly throughout the day and exhausted all options, but ultimately, public safety had to come first. We are sorry for any inconvenience this may cause.