Photo: BC Gov't

Work crews around the site of a massive rock slide in the Fraser River will be blasting away a large overhanging rock in an effort to avoid future slides.

A joint information bulletin from the British Columbia government and Department of Fisheries and Oceans says a rock scaling crew has drilled 50 holes in the rock to facilitate the controlled detonation.

It says the blast has been carefully designed to restrict the size of rocks that will detach, which prevents harming the fish that may be in the river below.

The rock slide has narrowed the river, creating a five-metre waterfall that is preventing many migrating salmon from getting through to spawning grounds.

The statement says the slide has raised concerns about the possibility of potential losses of critical salmon runs because it's blocking millions of salmon from migrating past the site.

Currently, sockeye and chinook salmon are starting to make their way up the river to the spawning grounds, and the statement says coho will head up the river later this the summer and into the fall.