by Bob Berg

Lake Levels Headed for Record Low

Lake Superior generally rises and falls over the course of a year. But this past year was different - the direction has all been down.

The lake’s water levels have been at their lowest in 80 years and may hit  new record low. Experts say it’s largely the result of the region’s severe drought, with little improvement predicted for early 2007.

In practical terms, lower water levels affect commercial shipping. Consider the John G. Munson, a bulk freighter owned by Great Lakes Fleet based in Duluth, Minnesota.

The Munson is a self-unloading ship with forward-mounted boom, which is a requirement for delivering coal to the Smurfit-Stone plant in Ontonagon, Michigan, says Gregg Ruhl, director of sales, marketing and traffic for Great Lakes Fleet. The Munson picks up coal in Sandusky, Ohio, and carries it to the mouth of the Ontonagon River and on to the company.

“We probably deliver about 100,000 tons of coal a year to Smurfit-Stone,” Ruhl says, explaining that the lake levels affect the water levels in the river.

The ship actually has to back out on the river when it leaves Smurfit-Stone (a maker of paperboard for boxes) and returns to the lake.

Because of lower water levels, the Munson is carrying a lighter load to Smurfit-Stone these days, handling about 15,000 tons per delivery compared with more than 17,000 tons when water levels were higher. Over a year’s time, that difference can equal about one shipload. The result is that, with slightly smaller loads, “the cost per ton goes up,” Ruhl says.

Ships taking on lighter loads to help navigate lower depths in channels and harbors has become more common on the upper Great Lakes in general, not just Lake Superior, making dredging one of the major issues identified by the maritime industry.

Commercial maritime traffic is not the only area affected by low water levels. On Michigan’s shore, there can be positive and negative consequences for fish, says George Madison, fisheries supervisor, Department of Natural Resources in Marquette and Baraga.

The drop in Lake Superior’s water level increases the lower slope of coastal rivers, causing an increase of river speed and in flow power, Madison says. Stronger flows will flush out the accumulation of silt and sediment, cleaning out river beds, helping to re-create pools and expose logs and gravel. That improves the in-stream habitat diversity for fish.

Madison sees northern pike as one of the main species affected by low levels. There could be a decrease in spawning habitat for one season, in places such as coastal estuaries and marshy spots. The following spring, if water levels are back up, those fish should recover.

Other places around the lake, sandbars have formed at river mouths, possibly inhibiting entry for fish, an occasional phenomenon on Lake Superior.

At Apostle Islands National Lakeshore in Wisconsin, docks are high enough above the surface of the lake that it’s become a safety issue. Some boats can slide underneath the docks, says park superintendent Bob Krumenaker.

Thus the park plans to install on some of the docks “vertical rub rails,” made of wood and rubber, to keep small boats from getting caught underneath the docks. “A typical boat would encounter at least two of these,” says Krumenaker.

Targeted locations include Rocky Island, where the Friends of the Apostle Islands has pledged more than $12,000, and Michigan Island if the Park Service has funds available.

Toward the end of last summer, Krumenaker noticed “a precipitous drop” in the lake level, adding that the park plans on dredging bays in at least one park marina in the spring to accommodate boats.

“We don’t really know what’s going to happen (with the lake level),” he says. But at Little Sand Bay, for example, “we’re going to do some dredging to try to keep (a depth of ) 5 feet of water there.”

Lower water levels affect private marinas, too, like the 200-slip Pike’s Bay Marina about 1.5 miles south of Bayfield, Wisconsin. “We’re down 18 inches, and probably more so, since September,” says Gordy Ringberg, general manager.

Normally, the water level in the marina is at least 8 feet deep, but this fall it was down below 6.5 feet in most parts of the marina.

Since Pike’s Bay Marina opened in spring 2001, it needed much dredging. But this fall, the marina brought in a dredge to clear a channel for two of its deep-drafted boats. Ringberg believes dredging will be needed at most area marinas in spring.

“With sailboats, we were hitting bumps that we didn’t know we had before,” he says, noting that all boaters will need to be very careful while navigating around the Apostle Islands.

The U.S. Army Corps of Engineers in Detroit reported in late December 2006 that Lake Superior, at 600.3 feet, was down 18 inches from the long-term average level of 601.8 feet for December. The Corps said it expected a further decline.

The lake fluctuates as much as 1 foot in a normal year as levels rise in spring and summer and fall later. In 2006, lake levels fell from near-normal in spring and kept falling.

An extreme shortage of rainfall in the Lake Superior basin is considered a major cause. The National Weather Service’s Climate Prediction Center suggests dry conditions will persist.

“As far as northeastern Minnesota and northwestern Wisconsin, it doesn’t seem like we’re going to see much improvement this winter and into early spring,” says Carol Christenson, meteorologist with the National Weather Service in Duluth. “We’re running 5 to 12 inches below normal” precipitation since the severe drought began last summer, she says.

Michigan’s Upper Peninsula has experienced a similar “precipitation deficit,” as weather experts call it.

Warmer weather and less precipitation may be a continuing trend, suggests Tom C. Johnson of the Large Lakes Observatory at the University of Minnesota Duluth.

Johnson, also a professor in UMD’s Department of Geological Sciences, suggests the warming trend in the region “is consistent with global climate models and what those have been telling us.”

The long-term effects of climate change in the region, in his view, would include a drop in water levels on Lake Superior, lower levels among the boundary waters (in Minnesota), and “we’re going to lose the boreal forest that we love so much.”

His colleague, Jay Austin, an assistant professor in physics at UMD and at the Large Lakes Observatory, says the two things that are likely contributing to the low lake level are evaporation and low precipitation. He also notes that 2006 may have produced the highest surface-water temperatures recorded on Lake Superior. Temperatures are taken from the National Oceanic & Atmospheric Administration (NOAA) buoys placed around the lake.

The highest daily water temp in the western arm was about 23.7 degrees Celsius (or 75 degrees Fahrenheit), he says. The previous high was around 21.6 C (71 F) in 1998 (an El Niño year). The average summer high temperature is around 18-19 C (64-66 F).

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