Jan 01, 2013 10:42AM
Rampant algae levels degrade water quality because as algae decompose, oxygen levels can drop low enough to kill fish. After the United States and Canada signed the initial Great Lakes Water Quality Agreement in 1972, many local governments banned detergents containing phosphorus and the algae problem faded, but it has returned in the past decade.
Analysts note that while the practice of planting crops without plowing the ground may help prevent erosion, it leaves high concentrations of fertilizer phosphorus in the upper layers of soil, where it easily runs off into waterways. A task force of academic and government experts has recommended more than 50 helpful practices, including providing funding and technical assistance for phosphorus reduction projects; authorizing state regulators to require pollution reduction measures in stressed watersheds; and working with farmers and equipment manufacturers to develop fertilizer application methods that avoid runoff.