Acid deposition, commonly referred to as acid rain, continues to damage Canadian ecosystems. Acidification of lakes and streams makes the water unsuitable to support some fish and other biota. Acid deposition damages forest soils by stripping the soil nutrients and increasing the release of toxic chemicals such as aluminium, as well as directly damaging some sensitive tree species.
In October 1998 all energy and environment ministers signed The Canada-Wide Acid Rain Strategy for Post-2000. The Strategy is a framework to address the problem of acid deposition. The long-term goal of The Strategy is "to meet the environmental threshold of critical loads for acid deposition across Canada." Critical loads are the maximum amount of acid deposition that an ecosystem can receive without significant damage. They vary substantially from one region to another depending on the local soil and bedrock conditions.
Regular reporting on SO2 and NOx emissions and forecasts and progress in implementing The Strategy is required. Commencing with the 2006/07 report, progress is reported biennially, alternating with the biennial Canada – United States Air Quality Agreement progress report which presents similar information.