WINDSOR, ONT. - A federal biologist fears that an upcoming expansion of Detroit's sewage treatment plant will have a catastrophic effect on Lake Erie mayflies and Ohio's $200 million-a-year sport fishing industry.
Bruce Manny of the U.S. Geological Survey's Great Lakes Science Center in Ann Arbor, said chemically treated sewage water flowing down the Detroit River will bring heavier doses of chemicals to Lake Erie's western basin, which ranges from Toledo to Port Clinton.
Mayflies were able to recover a few years ago, resulting in one of the Great Lakes region's biggest environmental success stories. But Dr. Manny fears they will disappear again once the $106 million Detroit sewage plant expansion is completed in about two years.
“Almost half the fish in Lake Erie eat the mayfly,” he said. “My concern is: Are we poisoning them [the mayflies] out again?”
Another scenario is just as gloomy: having mayflies survive and enhance the food chain pathway in which chemicals can move from mayflies to fish to humans, Dr. Manny said.
Mayflies burrow in lake sediment for two years before reaching adulthood. They are about 30 percent body fat, higher than some other insects, he said.
Cancer-causing chemicals such as polychlorinated biphenyls, known as PCBs, cling to body fat.
Dr. Manny, who has specialized in Lake Erie fish biology for 20 years, voiced his concern in front of a roomful of scientists here yesterday during the final day of a U.S.-Canada conference called “Lake Erie in the Millennium.” The two-day event drew 130 researchers from both sides of the border.
While many fish species can survive without mayflies, Dr. Manny said certain fish, such as yellow perch, would not reach their growth potential without them. He noted that the disappearance of mayflies stunted the growth of yellow perch years ago.
Detroit's wastewater treatment plant has long been viewed by regional scientists as one of the largest sources of pollution in the Great Lakes, with a history of environmental violations dating back almost to when former President Nixon signed the Clean Water Act in 1972. That act, together with the U.S.-Canada Great Lakes Water Quality Agreement, marked the advent of modern regulation of water discharges from sewage plants and manufacturing facilities.
In February, 2000, a U.S. District Court order required closer federal oversight of the Detroit sewage plant and assigned operation of it to Detroit Mayor Dennis Archer.
Phil Argiroff, superintendent of Michigan DEQ's municipal design review and operations unit, said the state agency endorsed the project because the Detroit facility needs greater capacity and flow rate to address the amount of raw waste that pours into the Detroit and Rouge rivers during heavy storms. Otherwise, the excess goes untreated and flows into the Detroit River and western Lake Erie.
Dr. Manny said he is skeptical about what's touted as an improvement, given the Detroit plant's troubled history. He said he believes the increased capacity was allowed largely to keep pace with Detroit-area sprawl.
Hydrology studies show 93 percent of the flow into Lake Erie comes from the Detroit River, he said.
Ohio's most well-known mayfly researcher, Dr. Ken Krieger of Heidelberg College in Tiffin, said he was intrigued by Dr. Manny's analysis. He said he was not sure whether he could agree, though, until he learns more about the Detroit project.
Dr. Krieger said the key is whether the Detroit project is as effective at addressing untreated waste as the Michigan DEQ predicts.
The conference was the first time in years that officials became so public about linking the effects of water quality on the Detroit River with Lake Erie in terms of research. On Tuesday, U.S. Rep. John Dingell opened a corresponding Detroit River conference, called “State of the Strait,” by announcing he will introduce legislation to designate much of the southern part of the river as an international wildlife refuge. Similar legislation is expected to be introduced on the Canadian side.