The town of Lake Cowichan on Vancouver Island will start using pumps to keep the local river flowing, due to one of the most severe droughts its watershed has experienced.

Water from Cowichan Lake will start being pumped into the Cowichan River on Thursday.

Catalyst Crofton, the company that will manage the process, says 11 droughts have plagued the Cowichan basin since 1998.

This year has been the extreme, it says.

Brian Houle, the company's environment manager, says dry summer conditions and a low snowpack led lake levels to sink low enough to put the town's prime water source in severe danger.

"We're now at a point where gravity will not sustain the river. If we're not able to put pumps in operation, the river flow would begin to diminish," Houle said.

An image of an overly dry Cowichan Lake in 2012. (Parker Jefferson)

Pumping has been authorized by the Ministry of Forests and will continue until water levels naturally restore themselves this fall.

Houle says efforts have been taken to minimize damage to the environment and wildlife, including a mesh screen to protect fish from being sucked into the pumps.

A local resident has placed markers on the lake and river to deter people from any hazard areas. The company says the area around the weir spill gates, the weir and the lake pumps and discharge area in the river will remain inaccessible.

Houle says boaters should exercise caution when out on the water.