While sustained governmental and public efforts have measurably improved Great Lakes water quality, rapid reduction in ice cover and the resurgence of some pollutants like excess nutrients are among the indicators currently raising concerns," states a news release from the International Joint Commission, a binational board that oversees U.S. and Canadian boundary waters issues.
The Joint Commission's report released Tuesday is an assessment of 16 measures of the lakes in terms of their chemical, biological and physical integrity.
The release says that the seven indicators of chemical health show "mostly favorable results" since 1987, but "some data also reveal a leveling off or even a reversal of reductions in toxic chemicals such as mercury and nutrient loadings in the past decade and earlier."
The chemical health of the lakes has indeed in many ways improved dramatically since the passage of the Clean Water Act of 1972. But that landmark piece of legislation never addressed contaminated ballast water discharges from overseas freighters, and the lakes' biological health has suffered greatly because of that.
"For example, the small, bottom-dwelling shrimplike organism, Diporeia, an important part of the food chain, was once abundant in cold, offshore regions of the Great Lakes but is now completely absent from large areas of Lakes Michigan, Huron, Ontario and Erie," states the Joint Commission release. "Also, from 1987 to 2006, 34 new non-native species became established in the Great Lakes, causing extensive and costly damage to the ecosystem."
On the brighter side, no new species have been discovered since 2006 that can be attributed to ballast discharges. The Joint Commission points to regulations that force freighters to exchange their ballast water with mid-ocean saltwater as a likely reason for the apparent success. But conservation groups contend that the ballast exchanges and even new rules that will force shippers to treat their ballast discharges to kill unwanted organisms aren't adequate protection.
As for the physical health of the system, the Joint Commission reports that warming temperatures appear to be taking a toll.
"The two physical indicators show rising surface water temperatures and reduced ice cover, likely signals of climate change," states the release. "Warming Great Lakes raise concerns about maintenance of native coldwater fish species and an increase in algae blooms, among other effects."
Warming temperatures are likely also tied to prolonged low water levels on the upper Great Lakes, and the Joint Commission recently decided to recommend that the U.S. and Canadian governments explore some sort of physical structure to slow flows on the St. Clair River, the main outflow for Lakes Michigan and Huron.
The report follows last year's updating of the Great Lakes Water Quality Agreement, a binational deal between the U.S. and Canada to maintain and protect their shared lakes.
To see a copy of the report: http://ijc.org/en_/Biennial_Reports