The Great Lakes drainage region extends from Thunder Bay, through to Southern and Eastern Ontario. Its 10,998 km2 of built-up area, accounting for 3.5% of the total area, was the highest in the country in 2011. Natural and semi-natural area accounted for 85.4% of the landscape, followed by arable land (10.3%) and smaller amounts of natural land for pasture (0.8%).
This drainage region had the highest population in the country in 2011 at 11,287,184 in 2011, with a population density of 54.7 persons/km2. Population was up 70% compared to 6,632,154 in 1971.
Surface freshwater intake from thermal-electric production, manufacturing, drinking water plants, mining and irrigation was 23,461 million m3 in 2013, by far the highest in Canada. These withdrawals account for 70% of the water intake from the 25 drainage regions.
The average annual water yield was 133.3 km3 over the period 1971 to 2013. The water yield per unit area was 0.42 m3/m2, compared to 0.35 m3/m2 at the Canada level. Monthly water flows peak in April. Evapotranspiration was the highest in Canada at 0.48 m3/m2.
Sources of nitrogen and phosphorus residuals in the environment include fertilizer application, livestock and poultry production and industrial emissions. On average residual soil nitrogen on agricultural land was 37.5 kg/ha compared to 23.2 kg/ha at the Canada level. In 2014, 106,099 tonnes of nitrogen-containing substances were air, land and water by industrial facilities. These emissions accounted for 14% of direct industrial emissions across Canada.
