16 Ways to Measure the Health of the Great Lakes

IJC staff
May 15, 2013

It’s time for a Great Lakes checkup.

The International Joint Commission has released its 16th Biennial Report on Great Lakes Water Quality. The report offers an update on how the health of the five lakes has changed since 1987, when the U.S. and Canadian governments signed the Great Lakes Water Quality Agreement.

Coincidentally, the 16th Biennial Report focuses on 16 indicators, selected by experts, on the chemical, physical and biological integrity of lakes Huron, Ontario, Michigan, Erie, and Superior.

Here’s a quick look at the diagnosis:

Seven indicators of chemical integrity for the lakes show favorable or stable results.

Concentrations of toxic chemicals have dropped in herring gulls, fish, sediments and mussels, for instance. Still, phosphorus loading from sources such as sewer overflows is a problem in places like Lake Erie, where excessive algal blooms have re-emerged. Some data also reveal a leveling off or even a reversal of reductions in toxic chemicals like mercury.

Five biological indicators show mixed results. That includes 34 nonnative species that became established in the lakes from 1987 to 2006, mostly from ballast water discharges from ocean-going vessels. In better news, no new invasive species have been introduced via ballast water since 2006.

Two physical indicators --- surface water and ice cover --- both show a warming trend in the lakes, which suggests that climate change is having an effect.

Two performance indicators also are evaluated in the 16th Biennial Report, with more mixed results. The first --- Areas of Concern, or toxic hot spots in the lakes in Canada and the U.S. --- have decreased by four due to restoration efforts, and about a quarter of impairments of the remaining spots have been removed due to environmental improvements. The second performance indicator shows that beach closings are still common due to high bacteria levels. But, the number of closings has remained fairly stable during the last 10 years (so closings aren’t increasing).

Highland Glen, Ontario, Canada. Photo by Jimmy Brown. Highland Glen, Ontario, Canada. Photo by Jimmy Brown. 

To sum it up, the 16th Biennial shows significant achievement, the need for further investments and action, and new concerns on the horizon.

For more details, see the short and long versions of the report, and a news release.

For the future, Commission has suggested that the governments provide the public with more information on the health of the Great Lakes, recommending that Canada and the U.S. establish a user-friendly, basinwide system for ecosystem status information, to be used by the public and scientists. That would include issuing a “report card” in future years for different indicators and trends involving the health of the lakes.

IJC staff