City workers have declared war on the ice clogging the river that winds its way through Canada's capital.
The annual battle on the Rideau River pits thick frozen slabs against an arsenal that includes giant saws, sticks of dynamite and a bizarre boat with giant ice-smashing clods.
The late-winter ritual is intended to ensure ice won't clog the spring run-off and flood homes and public buildings along its banks.
Beginning in February, city workers cut channels into the ice with large saws to prepare for demolition in early March.
"Following that, they'll drill some holes in strategic places so they can place dynamite," says Jason Staniforth, the City of Ottawa's manager of core roads. "Then they use explosive charges to send the sheets of ice down the falls."
The $500,000 operation, paid for by the Rideau Valley Conservation Authority, also includes a so-called Amphibex Excavator, designed and made in Canada by Normrock Industries.
The powerful boat, with its ice-smashing arms, was introduced in 1992 to cut down on the use of dynamite, which can damage ecological systems and bridges, says Staniforth.
The Amphibex also features a hydraulic boom with a bucket that scours the river, bashing through the ice.
Prior to the Amphibex's introduction, as much as 8,000 kilograms of dynamite would be used, scarring the riverbed and killing some wildlife.
Today, only between 700 and 1,500 kilograms is used, limiting the damage.
The annual ice-smashing exercise in Ottawa has been in effect for more than a century.
Similar ice-breaking operations are undertaken on the Red River in Manitoba.
The city expects to wrap up the operation by April.