These studies showed that phosphorus was the main cause of algal blooms, leading countries around the world to take steps to reduce the amount of phosphorus entering waterways.
Excessive growths of noxious algae plague many lakes and rivers and this, arguably, is the leading water quality problem in the world. Several important lakes in Canada are affected including Lake Erie, Lake Ontario, Lake of the Woods, and Lake Winnipeg. In the 1960s and 1970s, IISD-ELA researchers conducted controlled nutrient addition experiments in several lakes to identify the conditions suitable for developing strong algal growth in lakes. Results from these studies were striking, and identified phosphorus inputs as the key factor driving algae blooms. This led countries around the world to take steps to reduce the amount of phosphorus entering waterways.