The Clean Water Crew
place. In the past, heavy rains washed a large quantity of it directly into the Big River. Lead mine tailings also affect a number of other streams in east central and southwest Missouri.
Weithman says the spill of over 100,000 cubic yards of lead tailings into Big River in the early 1980s caused two problems. "The material fills in all the crevices between the gravel and the cobble on the bottom of the river, killing aquatic insects and ruining spawning sites for fish. It also becomes available to all of the organisms in the stream and is bioaccumulated. The lead goes up the food chain to the higher predators." The higher predators in this case are fish, and Missourians are advised not to eat them. Lead in the human body causes birth defects, mental retardation and a legion of other problems.
The southeast quadrant of Missouri is earthquake country. A major temblor could liquefy the Big River mine tailing piles, creating a problem that would dwarf the current situation.
Missouri is also still contaminated with chemicals used many years ago. These include DDT, dioxin and chlordane. These chemicals are estrogenlike hormone mimics. Wildlife exposed to them can have offspring that are incapable of procreating. (There is a human link, too. Many women in western countries have dioxins in their breast milk, and their risk of breast cancer is much higher than normal. PCBs are linked to lowered fertility in men.)
The Conservation Department is concerned with chemical contaminants because they can affect the growth and reproduction of fish and other aquatic species, and also because some of the chemicals accumulate in fish.
In the 1960s we experienced high levels of DDT and the chemicals it broke down into--dieldren and endrin. These chlorinated hydrocarbons are called hard chemicals because they take many years to break down. Chlordane is similar in that, once in the environment, it remains toxic for a long time. "These chemicals have a long life," Weithman says. "We still see significant levels in fish. Overall, levels are declining, but it is a slow process."
Concern for fish exposed to these chemicals and for anglers who catch and consume them prompted the Conservation Department to form a cooperative agreement with the Department of Health. Conservation Department biologists collect fish tissue samples from a variety of locations around the state so that the Health Department can set realistic advisories for fish consumption.
Water contamination by mercury is