As the nation was reminded by the drinking water tragedy that is still unfolding in Flint, Mich., high levels of lead and other heavy metals are hazardous to human health. And when dumped into rivers and streams, these metals can endanger aquatic life as well.

Although naturally occurring in small amounts, heavy metals such as zinc, copper, and lead pose a significant threat when released in higher concentrations by industrial facilities. Mining, metal manufacturing, and metallurgic processes such as galvanizing are common sources of zinc, copper, and/or lead pollution.

All three metals bioaccumulate in fish and other aquatic life, meaning they build up in the animals’ bodies over time, and become more concentrated higher in the food chain.

Bioaccumulation can lead to serious physiological damage over even a short time period. Exposure to any of these three metals can cause ion imbalances in fish that lead directly to cellular impairment in gills, kidneys, and other vital organs. Loss of gill function frequently leads to death.

Copper has also been shown to impair immune response in fish. When present together, zinc and copper can harm fish more severely than either metal would on its own, causing death at lower concentrations.

Even at non-lethal levels, zinc and lead can inhibit calcium uptake in fish, hindering reproductive function. Lead can also damage the central nervous system, leading to behavioral abnormalities or death.

Noting the harm that zinc, copper, and lead can cause to aquatic life at elevated concentrations, the EPA has designated these metals as “toxic pollutants” under the Clean Water Act.

By taking aim at industrial polluters such as Connecticut Galvanizing (see 2016 Summer – NELC Sues Metal Galvanizer for Clean Water Act Violations), NELC is helping to protect our streams and rivers from the destructive impact of heavy metals.