The family of a mother and son, who died after their vehicle plunged into a canal north of Toronto, continue to grieve as Bradford's mayor says the tragedy could have been prevented.

Cassandra Read, 32, was driving on Canal Road, just east of Highway 400, between Newmarket and Bradford, Saturday night. She lost control of her vehicle on the snow-covered, icy road.

With no guard rail in place, the SUV tumbled down a small embankment and then plunged to the bottom of the Holland Marsh drainage canal. Read and her four-year-old son Taylor were trapped inside.

Read was supposed to go to Bradford to drop her son off at her friend's house for babysitting.

The babysitter, Crystal Pittman, was speaking to Read on her cell phone as the SUV went under. It is unclear if the cell phone was a factor in the accident.

Brenda Read, Cassandra's mother, spoke to CTV Toronto about her overwhelming grief as she prepares to bury her daughter and grandson on Thursday.

"I didn't believe it because I know Cassandra is strong," Brenda said through tears on Monday. "She would have risked her life for Taylor's, I know that for sure."

Attila Jagodics lives nearby and ran to the canal after the accident but he said there was little he could do.

"By the time I got out we couldn't spot the vehicle or anything else," Jagodics said. "They didn't have too much of a chance."

Rescuers tried to free the pair from the SUV but were not successful.

Bradford's mayor, Frank Jonkman, has advocated for an $18 million plan to move the canal away from the roadway. He said his efforts, and those of the community's drainage commissioner, have been frustrated by government bureaucracy.

"We've run into a number of obstacles from the different ministries involved," Jonkman said Sunday. "We need to do study after study and now we've got two people dead."

He said that officials have been trying since 1993 to get approval to shift the canals and to create a buffer zone along the road, Canadian Press reported.

Bradford's drainage superintendent Art Janse told CP that the efforts have been stalled by environmental assessments for the Ministry of Fisheries and Oceans.

The canal has claimed 11 lives in the last 10 years.