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Water quality is a general term used to describe the physical, chemical, and biological characteristics of lake, river, or stream. Although scientific measurements are used to define the quality of water in a given lake, river, or stream, it's not a simple thing to say that "this water is good," or "this water is bad." To help understand why the state, cities, counties, universities, and watershed groups collect water samples, analyze these samples, and decide how things measure up, it is important to understand some basic water quality terms and concepts. Where possible, we have provided links to laws, regulations, and other educational materials that explain these concepts in greater detail.
The Federal Water Pollution Control Amendments of 1972, more commonly known as the Clean Water Act (CWA), provide the framework for how we view water and its overall quality. The CWA contains a basic objective for all Americans:
"Restore and maintain the chemical, physical and biological integrity of the Nation’s waters."
A secondary, but equally important goal of the CWA is that we need to work towards achieving:
"Water quality which provides for the protection and propagation of fish, shellfish, and wildlife and provides for recreation in and on the water."
To achieve these goals, all States and authorized tribes are required to create rules and regulations that protect water quality. In Indiana, we have state water quality standards [PDF] that describe how we will protect and maintain water quality, acceptable limits for various types of pollutants, and how we will allow industry, agriculture, cities and towns, and ordinary citizens to use our water resources in ways that are protective of humans and the environment.
The U.S. Environmental Protection Agency provides a detailed overview of the Clean Water Act, as well information on water quality standards as online educational presentations that are available for anyone interested in learning more about these topics. Two points to note:
When many people think of water quality, the first image that comes to mind is the amount, or level, of chemical pollution in a waterbody. Federal and state agencies are very concerned about levels of chemicals such as mercury, PCBs, chlorine, and hundreds of other compounds. Even certain types of bacteria are a concern. Our water quality standards contain numbers, or limits, that describe how much of a given chemical can be in a waterbody and not cause harm to humans or the environment. There are a number of key nonpoint source pollution parameters that are helpful to understand in greater detail.
In addition, we are concerned about the physical properties of our waterbodies. We have regulations that require we keep the physical properties of our water clean. Clean waters are waters that are free from things like oily sheens, abnormal color and odor, nuisance algae, high levels of sediment, or other conditions that could harm the humans and environment or create problems for humans that want to swim or boat in these waters. We also are concerned that our rivers, streams, and lakes have the right habitat to support healthy populations of fish, freshwater mussels, and even insects that are part of a clean environment.
Clean water is important to all aspects of our lives. Our laws and regulations not only protect water for environmental purposes, but for the use of water by humans. We have regulations that insure our rivers, lakes, and streams can have a well-balanced aquatic community, be usable for public and industrial water supplies, are available and usable for agriculture, and in special cases, have additional protection for high water quality.
In all cases, we insure that the most protective of any of these uses on a given waterbody applies to any activities. Our regulations require that these existing beneficial uses shall be maintained and protected. Water quality cannot become worse and in turn, hurt these uses.