How Does Chlorination Affect Marine Life?

Chlorination is the process of disinfecting water and wastewater at treatment plants to remove bacteria and microorganisms from the water; water that is not chlorinated can carry diseases such as typhoid and cholera, according to the Chlorine Institute. The effects of high chlorine levels in water are felt for a short period until the chlorine is diluted by water and other chemicals.

  1. Chlorine

    • Chlorine is a highly reactive gas of a yellow-green color that has a strong odor that can be smelled by humans at levels over 0.3 parts per million. Chlorine is a naturally occurring element of the planet Earth, the release of chlorine in wastewater is controlled by the U.S. Environmental Protection Agency at levels that do not cause any damage to humans or the environment. When released into the atmosphere, chlorine can combine with chemicals in water or be dispersed naturally into the atmosphere. Alongside water treatments, the major uses of chlorine in the United States are in the production of ethylene dichloride, polyvinyl chloride resins and for bleaching paper products during the manufacturing process, according to the EPA.

    Water

    • The release of chlorine through chlorination has short-term effects on aquatic life, with chlorine water levels reaching 0.37 milligrams per liter the maximum even the hardiest fish can withstand, the H2O University reports. When combined with other chemicals in water chlorine can form trihalomethanes that last longer than free chlorine when released into the environment and can be fatal to all living things. Aquatic plants and animals do not store chlorine within their bodies at dangerous levels, according to the EPA.

    Fish

    • The level of chlorine within water has different effects on species surviving within oceans, lakes and waterways. Species of fish that are most susceptible to chlorine levels include Chinook and Coho salmon that can be killed by chlorine levels within water of 0.01 mg/L and brown trout that is adversely affected at levels as low as 0.02 mg/L, the H2O University reports. Other species of trout can be killed in as little as two days as levels as low as 0.006 mg/L.

    Oysters

    • Oysters require water to be pumped through their bodies for survival, chlorine levels of 0.01 to 0.05 mg/L oysters can struggle to pump water through their bodies and remain healthy. When the chlorine level within water reaches 1.0 mg/L oysters are killed. The maximum recommended level of chlorine for aquatic life and fish is 0.01 mg/L, according to the H2O University.