More than a dozen communities remain isolated from the mainland in Newfoundland, while thousands are without power in Nova Scotia, as the cleanup continues after the remnants of Hurricane Matthew battered Canada's East Coast.

Floodwaters have wiped out crucial roads and bridges in Newfoundland, leaving 17 communities cut off from the rest of the province until the routes can be re-established. Those communities remain under state of emergency declarations as crews work to clear the roads and, in St. Alban's, to find an alternative route to the single, washed-out bridge into town. A portion of the Trans-Canada Highway has also been destroyed in Terra Nova National Park.

An estimated 225 millimetres of rain fell over Cape Breton, N.S., in 24 hours during the storm, amounting to more rain in one day than fell over the entire summer. The water washed out sewers and septic systems, flooded basements, submerged cars and eroded roadways and the land under some residents' homes.

The damage is expected to result in millions of dollars' worth of insurance claims, as well as a push for federal aid.

However, some residents may not be able to make insurance claims, depending on how the water entered their home. A lawyer told CTV News Channel that some insurance policies won’t cover water damage if the water entered through windows or doors.

Nova Scotia Power says it will likely take until Friday for service to be fully restored in Cape Breton, where an estimated 20,000 customers remain in the dark. Fierce winds wreaked havoc with the island's power grid, toppling trees onto power lines and cutting off hydro service to as many as 144,000 homes earlier this week. NSP has called in additional help from New Brunswick to deal with the hydro outages.

St. Alban’s Mayor Jamie Leroux told CTV News Channel that power reconnection in town “could be this weekend or it could go later.” He advised people to keep a close eye on social media for minute-by-minute updates.

Maritime Electric says it has nearly finished restoring power to customers in Prince Edward Island, where there were up to 7,800 outages after the storm. P.E.I. avoided the worst of the storm, with very little flooding or damage to infrastructure.

That's not the case in Cape Breton. Many students remain at home this week because their schools are flooded, as the Cape Breton-Victoria Regional School Board scrambles to find alternatives during the crisis. But schools are expected to re-open Thursday morning, with the exception of Brooklyn Elementary.

Cecil Clarke, mayor of Cape Breton Regional Municipality, says the cost of damage on the island will likely be tens of millions of dollars. He has also asked for disaster relief assistance from the federal and provincial governments.

With files from CTV Atlantic and NTV