Jorge Barrera
Northern News Services

Yellowknife (Oct 22/01) - What is "run of the river"?

The term is enjoying a lot of currency lately as debate surrounding a mega-hydro project for the Mackenzie and five other rivers heats up.

The main differences between run of the river facilities and dams are the height of the barrier, how much pooling is created and how much the river is controlled.

How feasible is it? The Mackenzie River has massive hydro potential. Enough potential in fact that it could be the next big deal in hydro. According to the territorial government, the Mackenzie River could generate 10,500 MW of power. The province of Alberta generates 8,000 MW of power. The average home uses five kW of power; 1,000 kW equals one megawatt. "The territory has the hydro potential to be on par with the massive James Bay project in Quebec," said Trevor Weir, spokesperson for the NWT. But Weir said any projects in the territories would need to generate copious amounts of power to make it feasible for investors. There is no connecting power link between the territory and US markets and a link would cost millions. The link between Yellowknife and Snare Lake cost $25 million for 140 kilometres of line.

According to Trevor Weir, spokesperson for the Northwest Territories Power Corporation, run of the river facilities do not create big pools of water or a reservoir.

"The main difference is that run of the river facilities do not alter the flow of the river," said Weir.

Run of the river facilities do not stop the flow of water and rely mainly on the river's own power to generate energy.

"(The facility) is at the mercy of the river," said Weir.

The territories has one run of the river facility. The Dogrib-owned Snare Cascades on the Snare River uses the concept to generate about 32 MW of power.

The Snare River's path is not redirected. A low barrier called a weir stretches across the width of the river deflecting some water down an artificial channel but the main body stays on its natural course. The channeled water flows through a generator powering turbines. The emerging water flows back into the main river body.

This is a typical run of the river facility, said Weir, but it can vary widely depending on the amount of juice needed.

Run of the river installations do not stop the flow of rivers which rises and falls according to the seasons.

A dam controls water levels. At the NWT Power Corp owned Snare Rapids dam, Weir said the water levels change slightly over the course of a year.

"Maybe a foot or two," said Weir.

Dams change landscapes dramatically creating lakes and flooding flats.

Run of the rivers do have the potential to back up rivers but it never creates massive pooling, said Weir.

"If you go a quarter mile up river you can't tell any difference," said Weir.

Some of the major environmental impact created by run of the river probably comes from creating the artificial channel.

Weir said blasting created the Cascade's channel.

According to a report from Hydro Quebec, run of the river projects have the best "payback ratio."

The ratio is based on energy needed to maintain the project vis-a-vis energy it produces.

Damming comes a close second.

The report connects environmental impacts with the energy needed for maintenance.

Using this formula fossil fuels have the worst payback ratio because of the amount of energy used in extraction, transportation and processing.

Weir said run of the river projects impact the environment by raising water levels down river.