States are responsible for reviewing, establishing, and revising water
quality standards. The state adopted standards may be more stringent than required by
Federal regulation. Under provision of the CWA, EPA is to review and approve, or
disapprove the state-adopted water quality standards.
There are three main factors to be considered in establishing water quality
These factors are designation of uses, criteria, and antidegradation policy.
126.96.36.199 Designation of Uses. Each state must specify appropriate water uses to be
achieved and protected. In designating uses of a water body and the appropriate
criteria for those uses, the state must take into consideration the water quality
standards of downstream waters and ensure that its water quality standards provide for
the attainment and maintenance of the water quality standards of down stream waters.
States may adopt subcategories of a use and set appropriate criteria to reflect varying
needs of such subcategories of uses. At a minimum, uses are deemed attainable if they
can be achieved by the imposition of effluent limits required under Sections 301(b) and
306 of the CWA and cost-effective and reasonable best management practices for nonpoint
source control. The state shall provide notice and an opportunity for a public hearing
prior to adding or removing any use or establishing subcategories of a use.
Seasonal uses may be adopted as an alternative to reclassifying a water body
to uses requiring less stringent water quality criteria.
States may remove a designated use, which is not an existing use, or
establish subcategories of a use if the state can demonstrate that attaining the
designated use is not feasible because of naturally occurring pollutants concentrations,
or natural, ephemeral, intermittent, or low flow conditions or water levels.
The state is required to conduct a use attainability analysis unless
otherwise exempted in the CWA.
188.8.131.52 Criteria. States are required to adopt water quality criteria that protect
the designated use of the most sensitive use. Such criteria must be based on sound
scientific rationale and must contain sufficient parameters or constituents to protect
the designated use. States must identify specific water bodies where toxic pollutants
may be adversely affecting water quality, attainment of a designated water use, or are
at a level to warrant concern. Where a state adopts narrative criteria for toxic
pollutants, it must provide information identifying the method by which the state
intends to regulate point source discharges of toxic pollutants. Toxic pollutants are
those listed by the EPA under Section 307(a) of the CWA.