Every year, small boats in Canada spill enough fuel -- often only a splash or two at a time -- to fill an oil tanker.

They also pump chemicals and raw sewage into the water, drop plastics and other materials overboard, and leave their mark on lake bottoms and riverbanks.

It's not necessary, says George Balmer, head of Environment Canada's Enforcement and Emergency section in Whitehorse. Most of the environmental damage caused by small boats can be prevented.

In fact, says Balmer, the practices that create an environmentally friendly boat are mainly the same practices that create a safe boat. It's all related to attitude.

Take, for example, engine maintenance. When you change the oil in your motor, put the waste oil in a covered container, remove it from the boat and dispose of it ashore. That not only prevents spills into the water but also prevents spills into the boat and on clothing and gear.

When refueling, do it carefully. Even small spills accumulate, especially in marinas. They also create a fire hazard aboard the boat.

"Besides," says Balmer, "fuel is too expensive to waste."

Spilled oil and fuel accumulates in the bilge at the bottom of the boat, along with water from splashes and leaks. You can buy commercial bilge cleaner, a kind of detergent, but it should be mopped up rather than pumped into the water.

A better practice, says Balmer, is to use sorbants, a kind of sponge. The sorbant sheet floats on the water in the bilge and absorbs only the oil, not the water. The oil can be wrung out of it (and disposed of safely ashore) and the sorbant reused.

"They're cheap and there are all kinds of local sources for them, " says Balmer.

The best practice of all is good maintenance, he says. If the boat's hull doesn't leak, all the fuel lines and connections are checked and intact, and engine maintenance is done carefully, there will be very little in the bilge to clean up.

The boat engine itself can be a major polluter, Balmer says. Two-stroke engines use pre-mixed fuel containing oil, but only a very tiny amount of the oil is burnt. The rest is spewed out in the exhaust, straight into the water. Four-stroke engines have far less impact on the environment.

Another major source of pollution is sewage and waste water. Any boat big enough to have toilet and cooking facilities should also have a holding tank, says Balmer. It is now illegal to dump sewage in American waters and it soon will be illegal in Canadian waters, he says.

If you go ashore to do your cooking and camping, it's still important to dispose of waste responsibly. Good landing spots tend to be used again and again, Balmer points out, and no one wants to come ashore to old camping litter and "a toilet paper minefield."

"The rule is, if you take it ashore, drag it back to the boat," he says.

And don't throw it overboard. People will heave almost anything over the side of the boat -- beer bottles, batteries, plastic containers, dehumidifier salt, yellow rope, monofilament fishing line. It doesn't go away and it doesn't degrade, says Balmer. It just accumulates, usually around popular fishing and boating places.

Some lost and discarded things do active damage. Lost fishing lures and nets still catch fish, even if there is no one to haul them in. Crab traps must now have biodegradable panels, says Balmer. The old steel crab traps, if lost, sat intact on the ocean bottom for years, still catching crabs and constantly re-baiting themselves with the remains of previous victims.

Almost everything about a boat can be environmentally harmful, but it needn't be. It's just a matter of taking care, says Balmer.

The three general rules of environmentally friendly boating are the same rules that apply to safe boating, he says. Select proper equipment, maintain it, and follow careful procedures.

For more information about making your boat environmentally friendly, contact Environment Canada, Whitehorse, at (867) 667-3400.