If your image of a hydroelectric generating facility is a huge plant and a monstrous dam flooding vast tracts of land, think again. Think about microhydro.

Microhydro projects use modest amounts of water to generate modest amounts of electricity, enough to serve as little as a single household or as much as a small community.

Randy Clarkson, a Whitehorse engineering consultant, has been involved in both extremes of microhydro.

Clarkson was introduced to microhydro in 1980 when a friend, Doug Gilday, needed help with the engineering of a two-kilowatt microhydro plant to supply power to his home on the Carcross road.

Developing the small plant was educational for both men, Clarkson says.

"We learned two things then -- how easy it was to build a microhydro and how difficult it was to deal with electrical utility companies. Nothing's changed in the 18 years since then."

The small creek that serves the Gilday household could produce far more power than the household needs, Clarkson says, but feeding the excess power into the Yukon Electrical Company's distribution system wasn't economical. Even though the electricity was relatively cheap to produce, the utility wouldn't pay enough to justify expanding the development.

However, encouraged by the success of the family-sized microhydro project, Gilday and Clarkson moved on to something bigger. In 1985 they began work on a microhydro plant to supply power to the Yukon highway maintenance camp, Canada Customs office, and residences at Fraser on the South Klondike Highway.

"It took five years to get contracts and permits, and 90 days to build," says Clarkson. The plant is owned jointly by Clarkson and Gilday through their New Era Hydro Corporation.

The Fraser microhydro system has no dam and no overhead transmission lines. The main evidence of its existence is a small building sitting over a little stream, across from the Canada Customs building.

The source of power for the microhydro plant is a small glacial lake drained by Bryant Creek. Instead of building a dam, Clarkson and Gilday punched a hole in the glacial moraine, a natural dam, at the lower end of the lake and ran a three-kilometre pipeline to the small powerhouse at Fraser.

To minimize the environmental impact and help insulate the pipeline, the pipe is buried for most of its three kilometres, emerging only where it crosses the stream. Now, eight years after construction, the right of way has been reseeded and the grass has come back, says Clarkson.

Inside the powerhouse, water emerging at a pressure of 350 pounds per square inch drives a turbine. The turbine rotates a generator that produces up to 300 kilowatts of electricity.

That's enough electricity to serve a community the size of Carcross, says Clarkson. Forty percent of the plant's electricity is used for heating the buildings at Fraser. The remainder provides all other electrical needs, at a price of nine cents a kilowatt-hour.

"No one can say it's not economic," says Clarkson. He estimates that it would require a thousand barrels of diesel oil a year to generate the same amount of electricity with a diesel generator.

Fraser is the largest microhydro site in the Yukon, but there are several smaller plants, ranging from a 150-kilowatt plant in the Rancheria valley to a 1-kilowatt plant providing summertime power for a residence near Stewart Crossing.

Clarkson says he has identified enough potential microhydro sites to provide between five and ten megawatts of electricity. He estimates that up to 20 percent of the Yukon's electricity needs could be served by microhydro.

"The key thing is that the number operating now is small and the capacity is limited, but the potential is huge," he says.