Water quality standards

AuthorJeffrey G. Miller/Ann Powers/Nancy Long Elder/Karl S. Coplan
Chapter V:
Congress adopted two grand strateg ie in the Clean Water Act (CWA) to
determine pollution reduction requirements for point sources: technology-
based standards and water quality standards. Technology-based standa rds
reect what technology can do, and not what is needed to achieve water qual-
ity goals. Technology-based sta ndards require specic pollution limitations
based on what pollution control technologies are available for specic types
of point sources. ese standards are not aected by the water quality of
the receiving water body. As a result, technology-based sta ndards will rarely
achieve water quality t hat precisely meets the desired goals of a particular
water body. is means that implementation of these standards may result in
water quality that exceeds desired water quality goals in some water bodies
and water quality that does not atta in desired goals in other water bodies.
Water quality-based standards seek to achieve water quality that precisely
meets the desired goals of a particular water body. Water quality sta ndards
are goal-driven and are theoretically economically ecient. If water quality
standards are achieved in a particular body, no water qua lity-based pollu-
tion control is required. Conversely, if water quality standa rds are not met
in the water body, existing pollution sources must limit their pollution until
the standards are achieved, and generally no new point sources may dis-
charge into that waterbody.1 A water quality-based approach may encourage
new pollution sources to locate where they will discharge into pristine waters
rather than into already polluted waters. To counter this, an anti-degradation
policy (discussed below) can be included in water quality standards.
Unfortunately, water quality-based standards are dicult to develop a nd
administer. Even in a pristine natural state, water is not pure; in fact, many
substances d ischarged by man a s pollutants are already found in water as a
result of natural forces. Indeed, most of nature’s water is unt to drink—salt
water is a good example. Salt water, however, is not the only natural water
that is not potable. Most water in hot springs is too sulphurous to drink, and
groundwater and surface water that have been exposed to mineral-bearing
1. See 40 C.F.R. §122.4(i); Friends of Pinto Creek v. EPA, 504 F.3d 1007 (9th Cir. 2007).
252 Water Pollution Control, 2d Edition
rock formations may have unacceptably high mineral concentrations. Water
can be fouled by excrement from wild animals, and can also be contaminated
by excess nutrients that stimulate excessive plant growth (eutrophication).2
Water pollution control cannot bring surface waters back to a state of
nature, if only because we have changed the ear th so much that we do not
know what the quality of its waters would be in a state of nature. e objec-
tive of water pollution control—to provide clean water—poses a question
that continues to occur throughout environmental policy and regulation:
how clean is clean? e water quality-based strategy of pollution control
addresses the question of “how clean is clean” by asking what the desired use
of a particular water body is and by assuming that the desired uses will dier
for dierent water bodies.
Water quality standards consist of t wo regulatory actions: (1) designating
the desired uses of water bodies; a nd (2) establishing criteria that must be
met in the water bodies to allow t he designated uses. Two further regula-
tory actions are necessary to achieve water quality standards: (3) determin-
ing whether the criteria are met in each water body and, if they are not,
determining how much pollution must be eliminated to meet the criteria;
and (4)allocating any required pollution elimination among polluting point
sources and applying the allocations in national pollutant discharge elimina-
tion system (NPDES) permits. We will examine briey the theory of each
of these stages. In the next section of the chapter, we will examine how each
stage is actua lly implemented under the CWA.
In t heory, there are a great many uses that may be appropriate for sur-
face water. e highest use, in terms of water purity, might be for human
consumption without treatment. Maintenance of sensitive sh populations
might be another use. At the other end of the scale would be the use of sur-
face water as a sewer for industrial and human waste. Because desired uses do
not depend on the laws of science, but on the desires of people, use designa-
tion is essentially a political choice.
2. See discussion of eutrophication in Chapter I.
Water Quality Standards 253
Water must meet some level of purity to be suitable for all but the lowest
uses. For each designated use there may be a dierent appropriate level of
purity, which may be dierent for each pollutant. For example, water suitable
for use as human drinking water w ithout treatment must be pure enough
not to adversely aect huma n health. Establishing what concentration of
a given pollutant may adversely aect human health is a scientic process
(although many decisions on the frontiers of science also reect political or
policy choices). Based on scientic studies, EPA has set maximum contami-
nant levels (MCLs) for drinking water to protect public health under the Safe
Drinking Water Act, 42 U.S.C. §§300f to 300j-26, 30 0g-1, 40 C.F.R. pt.
141. ese MCLs could be adopted as the criteria for the designated use of
human consumption without treatment. An exa mple is mercury. e MCL
for mercury is 0.002 milligrams per liter (mg/L). 40 C.F.R. §41.62. us,
the water quality criterion for mercury in water designated for use by human
consumption without treatment would be 0.002 mg/L. at would be a
numerical criterion. Criteria can also be narrative, e.g., no oating scum or
visible oil sheen.
For a quick description of how the U.S. Environmental Protection Agency
(EPA) assesses the risk from pollution and the issues associated with risk assess-
ment, see Paul A. Locke, Reorienting Risk Assessment, E . F.,
1994, at 29. For a more comprehensive discussion of the issues, see Basic Infor-
mation About Risk Assessment Guidelines Development, 70 Fed. Reg. 17766-
01 (Apr. 7, 2005), available at http://www.epa.gov/raf/publications/pdfs/
Once the use has been designated for a water body and supporting criteria
have been adopted, the water body must be studied scientically to deter-
mine whether it meets the criteria. is is begun by a rather straig htforward
process of sampling the water a nd analy zing the samples for the pollutants
of interest. ere are well-developed methodologies to assure that the sam-
pling and a nalysis achieve reliable results. How will t he location of sa mples
inuence the results? W hat if samples a re taken immediately upstream or
immediately downstream from an important pollution source?

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