The City of Calgary has boosted security around one of the city's drinking water sources, preventing the public from driving to the Glenmore reservoir and treatment plant.

A sign on the street that used to be called 56th Avenue SW now states: "Private Road."

The street leads to the treatment plant and the dam, but today only approved visitors can drive past a security checkpoint on the road.

Dams and water treatment plants need to be protected, said Lee Newton, a member of the Alberta Security and Strategic Intelligence Support Team, which is the province's counter-terrorism agency.

"Basically those essential facilities, services or assets, if they were to be disrupted or destroyed would have a serious impact on the safety and well-being of Albertans generally," he said.

Security has been stepped up around such sites in Alberta since the terrorist attacks in the U.S. in September of 2001, but at some facilities it has taken longer to put needed measures in place, he said.

"At the end of the day there is a limit to what a corporation or a municipality or whatever it may be … can do in a financial year because of limited funds," he said.

People can still walk or ride bicycles near the Glenmore dam and the water treatment plant, but Newton said that could change one day because security measures are constantly evolving and access could be impacted by future threats.