International study team excuses St. Clair R. in Huron water crisis

Spiel · May 10, 2009

International study team excuses St. Clair R. in Huron water crisis

May 6, 2009

LAKE HURON A much-anticipated report on the role of the St. Clair River in lowering the level of Lake Huron has largely exonerated the Sarnia outflow while placing most of the blame for water loss on climate change.

On Friday, members of the International Upper Great Lakes Study (IUGLS) board released findings of an investigation to determine "whether the conveyance capacity of the St. Clair River has changed, to assess if there is ongoing erosion in the river bed, and to identify other factors that may be affecting water levels," according to the report's authors.

Titled Impacts on Upper Great Lakes Water Levels: St. Clair River, the draft study has concluded that erosion of the river is not appreciable at this point and is recommending that no remedial measures be undertaken to stopper the flow from Huron to Lake Erie.

Boaters, cottagers and tourist operators on Lake Huron have been pointing to the lake's unregulated outlet as a key factor in the draining of upstream H20, particularly since the river was dredged in the 1960s and has been impacted by other human activities since. But the IUGLS board has largely discounted those concerns, arguing that the situation on the St. Clair has stabilized and other forces are at fault for waning Huron water.

"A key finding from the range of studies of the sediment and hydrology of the St. Clair River is that the river bed has not experienced any ongoing erosion since 2000," reads the report. "Rather, the river bed appears to have been stable since at least 2000."

The study panel did document a deepening of the river bed over the period of 1962-2006, but attributes much of this to a "a major event or series of events," notably ice jams, that were experienced in the mid-1980s, and resulted in "a temporary increase in flows."

Packed ice, such as a major clogging that occurred on the St. Clair River in 1984, "can temporarily increase the force of the water's flow over a river bed by forcing the same volume of water to flow through a much smaller, constricted channel," the report notes. Water upstream of the jam gets backed up, while the flow under the ice is more intense than usual and "can trigger river-bed scouring," plus the depositing of sediment downstream. Further erosion occurs when the ice jam breaks up, the report notes.

Extreme fluctuations in the levels of the Great Lakes during the mid-1980s "could have played a role in the relatively rapid change in the river's conveyance as well," according to the report. But the increase in outflow from Lake Huron via the St. Clair did not continue unabated, the researchers say; by the end of the 1980s, the river's conveyance level "had returned to pre-change conditions."

Investigators determined that the "head drop," or difference in water levels, between Lakes Huron and Erie plummeted by 23 centimetres (nine inches) over the span of 1962 to 2006, with the ice-related erosion of the mid-'80s accounting for some of that.

But crustal rebound-the rising of the earth's upper layer in the aftermath of the last glacier-has also been a factor in dropping Huron water, as has, to an even greater degree, climate change. "This factor has become even more important in recent years, accounting for an estimated 75 percent of the decline between 1962 and 2006," reads the report.

Calling climate "the main driver of the lake-level relationships," the study authors point out that "there has been a persistent decline in net total supply of water to Lake Superior and Lake Michigan-Huron over the past two decades that has resulted in declining lake levels and a change in the relationship to Lake Erie."

Pinning Huron's water woes primarily on natural causes is not going over well with members of the Georgian Bay Association (GBA), which earlier commissioned its own hydrological study of changes to the St. Clair River and determined that shoreline alteration and mining activities at Huron's outlet are contributing to a loss of 12 billion gallons per day.

The GBA has been swift to criticize the findings of the IUGLS, accusing the study board of using flawed data, screening out other important information that might have yielded a more urgent response to the problem, and failing to react with an appropriate sense of alarm to the issues it does identify.

The IUGLS study confirms that "six billion more gallons of water are flowing out of Lakes Michigan and Huron per day as compared to 1971," according to a release from the GBA. Yet it refuses to recommend any structural changes, such as the installation of a weir or the laying of substrate on the river bottom, as the GBA had hoped might be the case.

"The fact that it completely dismisses such an enormous increase in outflow and recommends that nothing be done about it is very disturbing," said Roy Schatz, the founding president of the GBA Foundation, in a release.

Bill Bialkowski, a retired engineer and member of the GBA's Water Level Committee, suggested, in the same release, that the IUGLS panel ignored critical data. "The study board needs to move to a higher level of science in order to understand this complex river," he charged. "It appears that sources were carefully screened to support preconceived conclusions."

The report's authors, however, maintain that the research was sweeping and impartial. "The report is the product of intense effort by a 10-member binational study board of experts and public members, who commissioned 42 research projects that engaged over 100 scientists," they point out.

The St. Clair report is just one phase of an ongoing, multi-year study of the upper Great Lakes that was launched by the International Joint Commission, a quasi-judicial body established by the United States and Canada under the Boundary Waters Treaty of 1909 to prevent and resolve disputes concerning the shared freshwater resource.

Funded equally by the US and Canadian governments, the Upper Lakes study group will now proceed to the next stage of its mandate, which is to examine the outflow from Lake Superior to Lake Huron via the St. Mary's River and recommend any physical or regulatory changes that may be required.

In the meantime, a series of public meetings have been scheduled for input on the St. Clair River scientific report, including one slated for Little Current on May 20. The session will occur from 7-9 pm at the Little Current-Howland Recreation Centre.