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Lake Superior Water Levels Near Record Low.August 16, 2007 — NOAA hydrologists indicate that Lake Superior is nearing record lows for the month of August, a trend that if continued could break past record lows for the months of September and October. NOAA’s Great Lakes Environmental Research Laboratory is able to forecast lake levels 12 months in advance using current hydrological conditions combined with NOAA’s long-term climate outlooks.

“Lake Superior is less than six centimeters higher than its August record low of 182.97 meters which was set in 1926, and it looks as though the water levels may continue to plunge," said Cynthia Sellinger, deputy director of NOAA's Great Lakes Environmental Research Laboratory in Ann Arbor, Mich. "NOAA's lake level forecasts predict that there is a 15 to 20 percent probability that new monthly records will be set sometime this fall."

As of today, the level of Lake Superior was 183.028 meters. The record low level for September is 183.06 meters set in 1926. That is also the record low level for October, which was set in 1864. Records date back to 1860.

Lake Superior, with a surface area of 31,700 square miles, is second in area only to the Caspian Sea, and is greater than the combined areas of Vermont, Massachusetts, Rhode Island, Connecticut, and New Hampshire. For every inch Lake Superior drops, 529 billion gallons of water are displaced. In the past decade, 12.7 trillion gallons of water have left Lake Superior.

NOAA image of Lake Superior water levels in 2007 compared to record high and low water levels. Please credit “NOAA.”The lake has been decreasing by a rate of 10 mm every year since 1978, and has dropped a dramatic two feet during the last decade. The Great Lakes region has been experiencing warmer winters since 1997, and the combination of warmer air temperatures and less ice cover leads to increased evaporation rates during the winter. Also, with less snow pack, there is less spring runoff to replenish the lakes. (Click NOAA image for larger view of Lake Superior water levels in 2007 compared to record high and low water levels. Please credit “NOAA.”)

Observations of precipitation, evaporation, ice cover, snow pack and other factors are critical to support the forecast models that allow for lake level prediction. NOAA, other federal agencies and the international community are working to build a integrated system, the Global Earth Observation System of Systems, to provide relevant and timely environmental information such as this to users around the world. The goal is to achieve societal, economic, environmental and health benefits through an increased understanding of the Earth’s systems.

Lake Superior’s record low of 182.69 meters was set in April 1926, the same year the lake reached an averaged annual record low of 182.90 meters as a result of a major climatic event that led to the dust bowl. Sellinger said that dramatic water level changes are generally caused by major climatic events. This includes the record high lake levels in the 1980s because of extreme rainfall, as well as the most recent drop in lake levels that were partially caused by the strong La Niña event in 1998 that affected the jet stream through the Great Lakes area and led to extreme droughts.

Anthropogenic causes could contribute to lower water levels as well. Canals and rivers are often dredged in the Great Lakes basin to allow large cargo ships to pass. As rivers are dredged, the channels for water to flow out of the Great Lakes basin are broadened, allowing for more water to run out.

Lower water levels mean more dredging and less cargo for the shipping industries that rely on the Great Lakes waterway as an essential route from Africa, Europe, and Asia to ports like Montreal, Detroit, and Duluth. On average, for every inch of low water levels, cargo ships must reduce their load by 50 to 270 tons, therefore providing less cargo for the same amount of shipping time. The economic impact of reduced cargo capacity eventually trickles down to consumers.

The estimated Great Lakes $16 billion recreation boating industry and the $4 billion sports fishing industry have also felt the effects of lower water levels. With marinas either dredging, relocating, or closing down completely, boaters are having a hard time launching boats, as well as navigating shallow waters and trying to use docks that were built when water levels were two feet higher.

NOAA, an agency of the U.S. Commerce Department, is celebrating 200 years of science and service to the nation. From the establishment of the Survey of the Coast in 1807 by Thomas Jefferson to the formation of the Weather Bureau and the Commission of Fish and Fisheries in the 1870s, much of America's scientific heritage is rooted in NOAA.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.

Relevant Web Sites

NOAA Great Lakes Environmental Research Lab

NOAA Great Lakes Water Levels

Media Contact:
Jana Goldman, NOAA Research, (301) 734-1123