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Mercury in MN Water
Water resources and the quality of those resources are of particular importance to Minnesotans. Minnesota has 11,842 lakes over 10 acres in size and 69,000 miles of natural rivers and streams. Minnesota also borders Lake Superior, which is 20,364,800 acres in total size. Nearly 963,000 acres of Lake Superior, or 47%, is part of Minnesota. The first 680 miles of the great Mississippi River are located in Minnesota. A little over 20% of Minnesota is surface water, including wetlands. (1)
Fishing in Minnesota
Fishing Minnesota’s lakes and rivers is a favorite pastime of many Minnesotans. The U.S. Fish and Wildlife Service estimates that 1.3 million Minnesotans fished in 2001. (2) Just 10% of people in the U.S. purchased fishing licenses in 2001, compared with 31% in Minnesota. Minnesota is second only to California in the number of fishing licenses sold in 2001. (3)
Fishing is also big business in Minnesota. The total economic impact of fishing in Minnesota is $2.8 billion (in 2004 dollars), including retail sales ($1.4 billion); salaries and wages ($708 million); sales and motor fuel taxes ($103 million); state income taxes ($24 million); and federal income taxes ($114 million). An estimated 25,955 jobs in Minnesota are also tied to the future of fishing. (4)
Fish Consumption Advisories
Our fishing traditions are threatened in Minnesota because of mercury contamination of our fish. The Minnesota Department of Natural Resource, the Minnesota Pollution Control Agency, and the Minnesota Department of Health are all concerned about the size, type, and quantity of fish that Minnesotans eat because our fish, lakes and rivers are contaminated with mercury.
Minnesota has had a statewide fish consumption advisory for mercury since 1999. Minnesota is one of 45 states to issue fish consumption advisories for mercury and one of 21 states to issue statewide fish consumption advisories for mercury in freshwater lakes. (5) Because Minnesotans care so much about our water resources, Minnesota has one of the best lake monitoring programs of any state in the country.
The answer to the mercury problem is clearly not to fish less. Fish can be an important part of a healthy diet. The answer is to heed the fish consumption advice for your favorite fish and to work together to reduce mercury emissions at the source.
How mercury contaminates fish
Mercury is a naturally occurring element normally found in small amounts in rocks and soils. When a volcano erupts or rocks and soils break down through natural weathering processes, small amounts of mercury are released. Since mercury is an element, it never breaks down into a less dangerous form. Instead, it persists in the environment and can cycle for decades between land, air and water until eventually it is covered by sediments.
Human activity – and especially human energy consumption – has changed the pattern. The Minnesota Pollution Control Agency estimates that coal-burning power plants produce nearly 50 percent of the state's total mercury air emissions. Other major sources of mercury air emissions in Minnesota are taconite processing (21 percent) and product uses of mercury (29 percent). For more information on how mercury finds its way into our environment, please visit our Sources of Mercury page.
Mercury is emitted into the atmosphere through the smokestack gases when coal is burned, when products containing mercury are incinerated, and when taconite is processed. The mercury emitted into the atmosphere then becomes part of the global pool. Then, depending on the weather and the atmospheric chemistry, the mercury falls back to earth with rain or snow at varying distances from the smokestack. Once mercury reaches bodies of water, bacteria in those waters can convert it to a very toxic form that is dangerous to wildlife and humans, called methylmercury. The bacteria are eaten by plankton (microscopic organisms at the base of the food chain), the plankton are eaten by small fish, the small fish are eaten by ever-larger fish until the mercury has been concentrated as it has moved up the food chain. This process, known as bioaccumulation, explains why bigger and older fish contain the highest levels of mercury and pose the greatest danger to wildlife and humans.
Notes
(1) Minnesota has 20,525 square miles, or 13,136,357 acres, of surface water including wetlands (www.dnr.state.mn.us/faq/mnfacts/water.html). Minnesota has a total area of 86,938 square miles, or 55,640,320 acres (www.dnr.state.mn.us/faq/mnfacts/land.html).
(2) http://www.census.gov/prod/2003pubs/fhw01-us.pdf.
(3) See www.asafishing.org/asa/statistics/participation/fishlicense_2001.html, using a state population number of 5,059,375 from http://quickfacts.census.gov/qfd/states/27000.html.
(4) http://www.iwla.org/conserv/backgrnd/0817_state_fishing.doc.
(5)See http://www.epa.gov/waterscience/fish/advisories/factsheet.pdf.
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