Water Quality Protection

Abstract

Impaired water quality can result from natural causes, but the most common cause is anthropogenic pollution. Soil erosion leads to turbidity and sedimentation in water bodies. Organic wastes impart a high oxygen demand often culminating in low dissolved oxygen concentrations and nitrogen and phosphorus in effluents cause eutrophication. Pesticides, synthetic organic chemicals and heavy metals from industry, and pharmaceutical compounds and their degradation products can be toxic to aquatic animals or have other adverse effects on them. Toxins in drinking water can lead to several serious illnesses to include cancer in humans. Water bodies also may be contaminated with biological agents that cause aquatic animal and human diseases. Elevated sulfur dioxide and carbon dioxide concentrations in the atmosphere as a result of air pollution can influence water quality. Wetland destruction must be considered in a discussion of water pollution, because functional wetlands are important for natural water purification. Water quality regulations are important for avoiding conflicts among water users, minimizing public health risks of certain chemical and biological pollutants, protecting the environment, and preventing conditions that lessen the recreational and aesthetic value of water bodies. Most countries have developed water quality regulations with which effluents must comply. These permits typically have limits on concentrations of pollutants in effluents, and many times, there are limits on quantities of pollutants that may be discharged. There is a growing tendency to develop total maximum daily pollutant loads (TMDL) that specify the total quantities of selected pollutants that can be discharged into a stream or other water body by all permit holders. Standards with which municipal water supply operations must comply also have been developed to protect drinking water quality and protect public health.