Lake Water Quality - Outboards

Here are graphic results of an experiment done years ago looking for the effect of outboard engines on nutrient loading to lakes. For eight hours, I ran a modern two-cycle (left), a four-cycle (center) and an older (pre-1972) two-cycle outboard in the enclosures. By the way, nutrient loading from outboards turned out to be small except, perhaps, in densely used, nitrogen-limited lakes. We did not evaluate oil and gas loading or effects. (See Hallock and Falter. 1987. "Powerboat engine discharges as a nutrient source in high-use lakes." Lake Reserv. Manage. 3:172-181).