Mercury Pollution

Mercury is one of the most harmful pollutants faced by fish and wildlife. Toxic mercury is released from coal burning power plants across the country and accumulates in rivers, lakes, and forests.  

Why is Mercury a Problem?

Bass Fish

Mercury is a highly potent neurotoxin that impacts the function and development of the central nervous system in both people and wildlife. Exposure to mercury is particularly dangerous for pregnant and breastfeeding women, as well as children, since mercury is most harmful in the early stages of development.

Scientists have found alarming levels of mercury accumulation in a wide range of wildlife species, causing dangerous reproductive and neurological problems.

  • Fish have difficulty schooling and decreased spawning success.
  • Birds lay fewer eggs and have trouble caring for their chicks.
  • Mammals have impaired motor skills that affect their ability to hunt and find food.

In addition, some evidence indicates that elevated mercury levels can adversely affect species' immune systems. All these effects combine to create a severe threat to wildlife survival.

  • Airborne Mercury
    dark-eyed junco_MinetteLayne

    Until recently, terrestrial species that do not eat fish were thought to be safe from the harmful effects of Mercury. However, researchers have recently documented mercury in Bicknell’s thrushes, terrestrial birds that inhabit mountaintops in the Northeast, where habitats lie downwind of the coal-burning epicenters of Ohio, Pennsylvania, Indiana and Illinois. Read the full story.

Where Does Mercury Come From?

Mercury is a naturally occurring, toxic heavy metal. However, human activity has significantly increased mercury levels in the environment over the past several centuries. Once emitted to the air, mercury falls to the earth and builds up in our waters and soils where it is transformed into methylmercury--a highly toxic form that accumulates in the tissues of wildlife and people.


Mercury increases in concentration with each step up the food chain.

As a result, large predator fish such as walleye and trout can have mercury levels over one million times that of the surrounding water. In turn, people and wildlife who consume fish or other species with high mercury levels are at risk of serious health problems.

Coal-fired power plants are the single largest source of mercury contamination in the U.S., responsible for approximately 50 percent of human-caused mercury emissions. Other sources include waste incinerators that burn mercury-containing products and chlorine manufacturers. However, unlike these sources, power plants have not had to limit their mercury pollution.

Historic Air Pollution Standards Will Reduce Mercury Emissions 91 Percent

In December 2011, the Environmental Protection Agency finalized new air pollution standards that will result in the first-ever national limits on the amount of mercury spewing from the nation’s coal-fired power plants.

The new pollution limits on power plants will cut mercury emissions by 91 percent, while also cutting acid gas, arsenic, lead and nickel emissions.

National Wildlife Federation campaigned for these standards since 1999, organizing hundreds of thousands of NWF members and supporters to attend public hearings, sign postcards, make phone calls and urge decision makers to put stricter limits on mercury emissions. 

Read more about these new mercury standards >>

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