Lets start with this from the G&M:-
Toronto's police chief is admitting there never was a five-metre rule that had people fearing arrest if they strayed too close to the G20 security perimeter....... A ministry spokeswoman says the change was about property, not police powers, and did not include any mention of a zone five metres outside the G20 security perimeter. When asked Tuesday if there actually was a five-metre rule given the ministry's clarification, Chief Bill Blair smiled and said, “No, but I was trying to keep the criminals out.”
Even though it wasn't accurate, the public was left to believe the province had given officers the power to demand identification and detain anyone with five-metres of the G20 site. All weekend there were reports of police stopping people throughout downtown Toronto — often in areas nowhere near the G20 zone — demanding identification and to search bags and backpacks.
Public Works Protection Act, ONTARIO REGULATION 233/10 DESIGNATION OF PUBLIC WORKS This Regulation was filed on June 14, 2010. A current consolidation of this Regulation is not yet available on e-Laws. See Source Law for the text of this Regulation. Notice of additional information: On June 21, 2010 this Regulation came into force. There may be more recent events that are not included in this notice.
However with a bit of digging I found this:-
Filed: June 14, 2010
Published on e-Laws: June 16, 2010
Printed in The Ontario Gazette: July 3, 2010
area referred to in paragraph 1 of section 1
designated places referred to in paragraph 2 of section 1