Silent Spring 50th Anniversary Essay Series
Reversing the Ecological Impacts of Missouri’s Mining Legacy
By John Weber and Scott Hamilton
When modern Americans think about pollution and the environmental movement, they often think of the 1960s and 1970s as the time when “all those pollution issues” were handled. With publication of Rachel Carson’s seminal work Silent Spring, the passage of the Clean Air Act and Clean Water Act, and the formation of the Environmental Protection Agency during the same time period, it is easy to understand why folks would consider the issue of water, air and land pollution under control. Unfortunately, 50 years after the inception of the environmental movement such is not the case across the nation, and in the State of Missouri, one example of environmental pollution stands out above all others.
Missouri is home to some of the largest deposits of lead and zinc in the world, and as a result of the exploitation of these resources, thousands of square miles of lands are impacted by historic and on-going operations. The wastes generated by lead and zinc mining, and the toxic chemicals they contain, are the by-products of a lucrative industry that created, sustained and continues to define many towns in Missouri. Unfortunately, the impacts of lead and zinc mining are as enormous as the quantity of the ore in the mining districts.
Pollution originating from the mines and related facilities have impacted the air, water and soils of Missouri. Water quality in hundreds of miles of rivers and streams is affected by runoff as mine waste migrates from piles of tailings and impoundments. Both surface water and groundwater are polluted from mine shafts and collapsed mine workings. The wind, and the occasional tornado, blow contaminated dust into areas well beyond the mines. The net result is that toxic pollutants are continually absorbed by people, plants and wildlife.
Lead and especially zinc are toxic to plants. The metals stunt their growth, cause deformations of leaves and roots, and outright kill many plants. At lower levels of soil contamination that do not kill directly, the community of plants can be severely reduced in diversity so that only weedy species are left growing on mined areas. The consequence is poor habitat for birds and other wildlife. Further, lead and zinc are often ingested by wildlife when their foods (seeds, worms, plants, etc.) are coated with contaminated dirt particles. This is termed “incidental ingestion,” and significantly affects an animal’s survival, growth and ability to reproduce.
Animals in streams within mining districts often suffer the same fate as upland wildlife. Scientific investigations of many metals-impacted Missouri streams found reduced populations of crayfish in mining sites compared with healthy streams. Studies of fish exposed to lead demonstrate drastic muscular and neurological damage including scoliosis and paralysis, while elevated zinc damages gill membranes and suppresses immune response. The net effect of the elevated metals in streams is an ecosystem that is reduced in complexity, and largely composed of unhealthy organisms.
The Environmental Contaminants staff of the U.S. Fish and Wildlife Service Missouri Field Office works diligently to restore fish, wildlife and their habitats injured by lead and zinc mining. We played the central role in recovering over $60 million exclusively for the restoration of Missouri’s natural resources within the lead mining district, with the potential to recover tens of millions more dollars in the near future. We are working with the Missouri Department of Natural Resources to assess damages and prepare restoration plans. Recovered restoration funds will be used to restore and protect injured streams, wetlands, forests and prairies in Missouri. Specific restoration projects are just now beginning in southwest Missouri with projects in the southeast part of the state to follow next year. The environment of Missouri is not in perfect shape, but with continued efforts by the staff of the U.S. Fish and Wildlife Service and their partners, it will continue to improve as the years go by.