Great story by Hugh McDiarmid, Jr. in today's Detroit Free Press about research into the return of the Lake Erie dead zone. One slight clarification: one of the chief "modern pollution controls" that reduced the problem in the 1960s and 1970s was an effort by all the Lake Erie governments to limit phosphorus in laundry detergents. This happened over great resistance from the soap and detergent industry, but once implemented, was immediately effective. Which shows that getting to the source of the problem -- a product -- is often more efficient than treating it at the sewage plant. And our clothes still get clean.
http://www.freep.com/news/mich/deadzone26e_20050426.htm
The dead zone is not new. It occurs every year in late summer in the lake's shallow central basin off the Cleveland area, when organic matter like algae dies and settles to the bottom. As it decomposes, it eats oxygen, creating a blanket of water on the bottom several feet deep where living things can't survive.
In the 1960s -- fueled by phosphorus and other organic pollutants that fed huge mats of algae and weeds -- dissolved oxygen was virtually nonexistent in many parts of Lake Erie.
Modern pollution controls stemming from the 1972 Clean Water Act successfully reversed that problem, forcing polluters like the Detroit wastewater treatment plant, which sends effluent directly to Lake Erie via the Detroit River, to control its phosphorus emissions. The dead zone shrank accordingly.