Designated Uses One

After Congress passed the Clean Water Act, states were required to designate uses for each waterbody in their water quality standards. The designated uses for each state may be general, such as recreation and aquatic life, or they can be more specific, such as swimming and cold water fishery.

The Clean Water Act requires that designated uses for each water body must include recreation and aquatic life, otherwise known as the “fishable/swimmable” goals. (40CFR131.10(a)) Although the term “fishable” sounds like it only describes waters clean enough to support fish for us to catch, it refers more broadly to water quality that is good enough for a healthy balanced population of native aquatic life. “Swimmable” is shorthand for the quality necessary to support safe recreation in and on the water — and includes all types of water-based recreation. States may also designate other human uses such as fish consumption, shellfish harvesting and drinking water supply.

A water body’s designated uses must fully represent existing and potential uses. Not every existing use of a water body must be individually designated, but the designated uses must be broad enough and require strong enough protections for all existing uses.

Multiple designations

Water bodies are usually designated for several uses. Uses that don’t require high water quality (such as navigation) and uses that have water quality impacts (such as industry or agriculture) may be designated. Under the Clean Water Act, however, a stream cannot be “designated” to receive and carry away pollutants because the Act was specifically drafted to control such activities, not protect them. (40CFR131.10(a)).

In other words, the designation of a use does not imply a license to degrade water quality. In water bodies with several uses, the level of quality necessary to support the most sensitive designated and existing uses must be maintained. “Fishable and swimmable” water quality will always support agriculture, industry and navigation. But the reverse is not true. To settle for designation only of an agricultural, industrial or navigation use for your water is to concede the quality the Act was intended to provide.

The sensitivity of every use depends on the pollutant in question. Some uses require greater protection from certain pollutants, but not from others. For example, fish are likely to be more sensitive to high water temperatures than are swimmers. When a water body is designated for more than one use, protective levels for each pollutant and water body condition are to be set based on the use that is most sensitive to the pollutant or condition.

Importance of segments

In most states, larger water bodies are divided into discrete segments, each assigned its own designated uses and water quality criteria. Theoretically, these segments can be of any length or size but, ideally, they should reflect shifts in use and necessary levels of protection. For example, segments are commonly defined by tributaries, significant bends or constrictions in the water body, or changes in human uses (agriculture to suburban development).