The Great Lakes Water Quality
In the 1980’s, the banning or restriction of chemicals such as DDT and toxaphene and the adoption of tough pollution standards were among actions being lauded. “Victories” – such as the apparent recovery of a once-dying Lake Erie and the establishment of a world class fishery for salmon – were also being celebrated.
By 1997, numerous environmental conditions in the Great Lakes were reported by government agencies as mixed to good with exception of wetland and shoreline resources, stormwater runoff, and status of exotic species.
In hindsight, some of these reported conditions and trends were overstated, especially with respect to sewage outfalls. In the last 15 years, Chicago and Detroit have discharged tens of billions of gallons of untreated wastewater into the Great Lakes. Less massive but troublesome overflows also occurred at other cities along the Great Lakes. Levels of most pollutants entering the Great Lakes have indeed been drastically reduced. But, there is a polluter’s legacy manifested in what bureaucrats refer to as “areas of concerns (AOC’s)”. These are fairly large geographic areas where contaminants still impair our ability to use the water.
Michigan’s 13 AOCs have “legacy pollutants,” those that can persist in the environment for decades. This indicates that while regulating the sources of pollution is critically important, it does not equate with restoration. Pollutants persist in sediments, change forms, and bio-accumulate in the food chain – they don’t magically disappear.
Advisories to restrict consumption of fish owing to bioaccumulated chemicals are in still effect over many parts of the Great Lakes Basin. With exception of toxaphene, levels of contaminants are at least slowly decreasing. Yet, scientists continue to document increased levels in humans that eat more fish.
Toxic materials are only part of the array of pollution problems in the Great Lakes. High bacteria counts have prompted health officials to close some beaches and issue broader advisories against swimming. Phosphorous is being released in municipal and industrial sewage, and also comes from runoff of agricultural lands and fertilized lawns. There is interest in a statewide ban of phosphorous in fertilizers, a step seen as a logical and important extension of Michigan’s ban of phosphorous in laundry detergent in the 1970’s. But as in the case of toxic pollutants, bans won’t entirely solve the problem. That’s because the phosphorous already in the Great Lakes is consistently recycled. Phosphorous is a key nutrient that causes algae growth and subsequent oxygen loss. We have a large and growing “dead zone” in Western of Lake Erie that testifies to the detrimental impact of excessive nutrient loading.
Many of the changes in the Great Lakes’ values and pollution levels have been influenced by fluctuations in water levels and temperatures. The biological impacts of water temperature increases, in particular, are becoming obvious. Blooms of some of the more noxious algae forms are occurring earlier and more frequently.The next article will appear on October 8, 2012.