Questions remain about the collapse of two BC Hydro towers on Monday and what the utility company knew and who they warned about the risk before they came down.

On Monday evening a high voltage transmission line tower on the south bank of the Fraser River collapsed, pulling down a second tower and several wooden poles in a residential neighbourhood of Surrey.

The collapse also dropped several power lines into the Fraser River and forcing the closure of the Highways 1, 7 and 7B for hours, jamming traffic into Vancouver for several hours on Tuesday morning.

BC Hydro blamed the collapse on high water levels and fast moving water in the river which scoured out the base of the tower.

But Coquitlam Richard Stewart Mayor is calling for a full investigation into the collapse so municipalities can understand the risks associated with the infrastructure.

No warnings issued to residents

Stewart says BC Hydro knew there were problems but didn't warn anyone that dangerous high voltage lines could come down quite literally in their own backyard.

"Between them giving it a clean bill of health and a half hour later when an enormous catastrophe almost occurred, I mean we could have had multiple fatalities," said Stewart.

The second tower collapsed in a residential neighbourhood of Surrey, pulling down smaller power poles and dropping lines onto houses. CBC

BC Hydro should have notified affected municipalities so people could have taken precautions, says the mayor.

"Local communities need to know when there are risks associated with the infrastructure that goes through their communities," said Stewart.

"We need to know Hydro's plan for what happens if something goes wrong, because we were perhaps four hours trying to understand what Hydro is going to do about it, and that lasted until four in the morning, said Stewart.

"And only then did Hydro lay out a plan for trying to open up the traffic on the busiest part of the Trans Canada in time for rush hour," he said.

No indications of trouble, says BC Hydro

BC Hydro president Dave Cobb says the utility had no indication the tower was in danger.

Cobb says crews were monitoring the situation all week with divers and the tower that fell had just been surveyed minutes before and seemed fine.

"There was no indication it was at risk of falling into the water, so it was a very sudden event that happened," he said.

Cobb says it appears the tower's foundation suddenly gave way, but the utility won't know why until its technical crews report back in about two weeks.

"It certainly seems there was a sudden shift in the foundation that the tower was sitting on in the riverbank," said Cobb.

History of erosion in area

Maple Ridge pressure welder Mike Boileau says Metro Vancouver records will show the area is prone to scouring erosion.

Twenty years ago Boileau was the contractor who repaired a submerged water main in the same area of the river. He says it was split it half and fell into an 6 metre hole that was also created by scouring.

"I think the record of the GVRD on all their crossings in the area — they have more than one crossing — will indicate there was scour in that area," said Boileau.

There were no injuries linked to the collapse, but Boileau says BC Hydro should have taken the risk more seriously.

"These people were aware these towers were at risk to a certain extent, and not knowing the extent they were at risk, they put the public at risk of these power lines falling on them," said Boileau.

"They probably could have fallen on children. They could have fallen on anyone in traffic," he said.

Union questions safety record

Doug McKay, the business manager for BC Hydro's union, the International Brotherhood of Electrical Workers, says the utility no longer has the enviable safety record it once had.

"It used to be one of the top utilities in North America for safety. We are certainly not that over the last few years," he said.

McKay says he couldn't say whether that's affected maintenance, but says he has requested the relevant records.

"One of our biggest problems is that BC Hydro, the Crown jewel of this province is used as a cash cow by the governments," he said.

But Cobb says the problem was with the foundations, and not the tower itself.

"It is an aging system, there's no question about that, but again, this tower in particular -- there was no sign of failure of the tower itself or of a weakness or problem with the structure. It seems to be the foundation that under the water that caused this tower to fall," said Cobb.

Hydro infrastructure under review

In April the B.C. government set up a panel to review BC Hydro's plan to raise electricity rates 10 per cent in each of the next three years.

BC Hydro says it needs to raise $6 billion to upgrade dams and other facilities to meet the growing demand for electricity. The plan would cost homeowners $180 dollars more a year on average.

B.C. residents pay some of the lowest rates in North America for electrical power because of the province's large infrastructure of hydro dams.

But many of the facilities are 30 to 80 years old and in need of upgrades, according to BC Hydro.

The increases will help finance upgrades for about a dozen dams and generating stations around the province, including the 80-year-old Ruskin Dam that will require an $800-million investment.

New transmission lines will also be built to link existing and new substations.

BC Hydro is a provincially owned Crown corporation that reports to the Ministry of Energy, Mines, and Petroleum Resources.

It is regulated by the B.C. Utilities Commission, which controls the rates it charges and is mandated to provide reliable power, at low cost, for generations.