A new report finds that much of Canada's tap water remains at risk from contamination.

The Ecojustice report says progress in protecting water after the Walkerton disaster in Ontario a decade ago has faded.

The report finds only Ontario among the provinces worthy of an A grade for its water-protection efforts. Nova Scotia received an A minus, with other provinces picking up a B or C grade and the three territories ranging from C to D-.

The report says the federal government comes off worst — picking up an F — for a record that continues to worsen.

Grades by province Ontario: A

Nova Scotia: A-

Manitoba: B+

New Brunswick: B+

Newfoundland and Labrador: B

Prince Edward Island: B-

Quebec: B-

Saskatchewan: B-

British Columbia: C+

Northwest Territories: C

Alberta: C-

Yukon: D+

Nunavut: D

Federal government: F Source: Ecojustice "Waterproof 3"

For the first time, the report has expanded beyond treatment and monitoring to look at protection of drinking water sources.

However, it finds that only seven of 13 provinces and territories have taken steps to implement full-fledged source-water protection plans.

For example, Saskatchewan, which received a B-, has a good program for planning water sources, said Randy Christenson, the report's author. But those water sources aren't protected by any laws against potential threats. Enacting such laws could boost Saskatchewan's grade, he told CBC News.