August is National Water Quality Month: Part two

The term water quality is used often, but do citizen really understand how water quality is measured?

We use water every day in many ways from drinking to recreating to transporting goods and people. Since August is designated National Water Quality Month by the U.S. Environmental Protection Agency (EPA), this might be a good time to find out about how water quality of the waters of the U.S is determined.

Water quality is based on a set of standards and criteria. The standards are provisions of the state, territorial, authorized tribal or federal law approved by the EPA. These standards describe the desired conditions of a water body or the level of protection or how the conditions will be established in the future. The standards include designated uses for each water body and the criteria to protect those uses. See August is National Water Quality Month: Part one for more information on water quality standards.

As part of the water quality standards adopted by each state, territory or authorized tribe, the local entity also must adopt water quality criteria. The criteria in the standards outline the allowable concentration of specific pollutants in the entity’s surface waters.

Section 304(a)(1) of the Clean Water Act (CWA) requires the development of these criteria. As directed, the EPA developed criteria for human health and aquatic life and is currently working on the development of sediment and biological criteria. Each set of criteria is based on the most current scientific data and research and is designed to protect specific living organisms or ecological systems from the adverse effects of pollution.

In general, the criteria for each pollutant is listed at the level of concentration that would cause harm to human, aquatic or wildlife health if exceeded. States, territories and authorized tribes can adopt the EPA’s recommended criteria values or adopt their own.

The five criteria:

Aquatic life criteria

These values are based on how much of a certain chemical can be present in a water body before it may harm plant or animal life. The aquatic life criteria have been designed to protect both freshwater and saltwater organism’s exposure in both the short and long term.

Human health criteria

Pollutants can harm human health if people eat seafood or drink from contaminated water. Based on EPA research, values for this criteria outline how much of a specific pollutant can be in surface water before it may harm human health.

Microbial/Recreational criteria

Because bacteria or other pathogens can make surface water unsafe for human use, this criteria was developed to provide safe values for recreational activities, such as swimming.

Biological criteria

This criteria is being developed to provide indications about water quality based on what kinds and how many organisms are present in the water.

Sediment and bedded sediment criteria guidance

A variety of organisms, including worms and plants, live in the sediment at the bottom of rivers and lakes. These organisms can ingest pollutants found in the sediment or water column. Then the pollutant works its way up the food chain to threaten larger animals and humans. Since the food chain can be a conduit to pollution, the EPA has developed guidelines for the development of criteria on suspended and bedded sediment.

The criteria can be adopted either by adopting the EPA recommended criteria, adopting unique criteria based on site specific conditions or adopting criteria using other scientific and defensible methods. 

All of the criteria are developed to help insure the quality and use of water. As summer winds down and you enjoy your local water resources, think about how Water Quality Month is spotlighting efforts that improve the quality of your favorite lake, river or stream.

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