Regulating Water Quality Impacts of Urban and Highway Stormwater Runoff
Monday, July 21, 2008
By Anne Jones-Lee, G. Fred Lee
In early March 2008 the Los
Angeles Times and the Santa Monica Daily Press carried articles on law
suits that have been filed by the National Resources Defense Council (NRDC) and
other environmental groups against Los Angeles County and the city of Malibu
(Weiss, 2008; Daily Press Staff, 2008).
According to those reports, concentrations of fecal bacteria, heavy
metals, and other pollutants associated with stormwater runoff from Los Angeles
and Santa Monica exceed water quality criteria/standards. It appears that the law suit is designed
to compel Los Angeles County and the city of Malibu to manage urban stormwater
runoff to prevent violations of water quality standards in coastal waters that
receive the runoff.
While not involved in that
litigation, the authors have been involved in the investigation, assessment, and
management of, and in publishing on, water quality impacts of stormwater runoff
for more than 40 years. The senior
author has spent much of his five-decades-long professional career involved in
various aspects of the development, peer-review, application, and site-specific
adjustment of water quality criteria and standards both nationally and in
numerous states, for the protection of water quality/beneficial uses. This report highlights key technical
aspects of regulating water quality impacts from stormwater runoff from urban
areas and highways, with particular reference to compliance with water quality
standards. It also has
applicability to nonpoint source runoff/discharges, such as those from irrigated
agriculture. These issues, and
recommended approaches for developing appropriate water quality standards for
urban and highway stormwater runoff are discussed in greater depth by Lee and
Jones-Lee (2000a, 2004, 2005), as well as in numerous other publications,
reports, and presentations posted on their website (www.gfredlee.com) in the
“Surface Water Quality” section, “Urban Stormwater Runoff” subsection
(http://gfredlee.com/pswqual2.htm#runoff). For the past decade the authors
have also published an approximately monthly, email-based, “Stormwater Runoff Water Quality
Newsletter” that addresses current topics related to the sources,
significance, fate, and control of contaminants in urban, rural, and
agricultural stormwater runoff.
Past issues of those newsletters are archived on their website at
http://www.gfredlee.com/newsindex.htm; issues are identified by topics covered
at http://www.gfredlee.com/swnews_indexa.pdf.
Water Quality Criteria/Standards for
Stormwater Runoff
One of the problems faced by
stormwater quality managers and regulatory agenices is the application of
numeric worst-case-based water quality criteria and standards to situations
beyond those for which they have technically reliable applicability. In 1972, the US Congress mandated that
the US EPA develop national water quality criteria that would be protective of
the beneficial uses of the Nation’s waters. That requirement led to worst-case-based
water quality criteria that presume that the all forms of a contaminant to which
organisms are exposed are toxic or available to adversely affect beneficial uses
of the water, and that organisms receive chronic (long-term or critical
life-stage) exposure to the available forms of the contaminants. The use of enforceable standards
equivalent to those criteria ignores the fact that most chemicals that are
potential pollutants exist in aquatic systems in a variety of chemical forms,
only some of which are toxic/available to adversely impact water quality. Further, they do not give adequate
consideration to the fact that organisms do not necessarily receive long-term or
critical life-stage exposures to contaminants in ambient waters.
US EPA water quality criteria and
numeric standards based on them were not developed for the conditions typically
encountered with urban and highway stormwater runoff. Those criteria and standards were
developed for aquatic life protection under conditions more typical of a
continuous discharge of largely available/toxic forms of contaminants (such as
from a domestic wastewater treatment facility (POTW)) and that result in longer
term (chronic) exposure scenarios for aquatic organisms. Chemical contaminants in urban and
highway runoff, by contrast, are typically in largely unavailable, nontoxic
forms; organisms in receiving waters generally receive short-term, episodic
exposure to those discharges.
Nevertheless, since the
late 1980s, the US EPA has incorporated into NPDES permits for discharges to
surface waters (including larger (MS-4) stormwater runoff discharges), the
prohibition from violating water quality standards at the point of discharge or
at the edge of a defined mixing zone.
That requirement, however, has not been enforced for permitted stormwater
runoff by the federal and state regulatory agencies. Past court rulings have, in general,
concluded that the US EPA has discretion regarding requiring NPDES-permitted
stormwater runoff dischargers to manage urban stormwater runoff to prevent
violations of water quality standards.
The management approach that has typically been followed has been the
development of BMPs (Best Management Practices) to work toward compliance with
water quality standards, and the reporting of violations of water quality
standards by dischargers. The recently filed NRDC lawsuit attempts to eliminate
the current exemptions to meeting water quality standards that are being allowed
by regulatory agencies.
One of the foremost reasons that
the US EPA and state regulatory agencies have not required compliance with water
quality standards applied to stormwater runoff is the very high cost of
compliance to attain no more than one exceedance by any magnitude in three
years, i.e., the conventional NPDES requirements for wastewater discharges. It is estimated that the costs of
property acquisition, construct of a collection system, storage facilities, and
treatment works, and the operation of the treatment works would translate to
several dollars per person per day for the population served by the treatment
works. The bulk of the cost is
associated with the acquisition of property and the up-sizing of the collection
and treatment works to manage the very high stormwater flows that can occur
during major stormwater runoff events.
The evaluation and management of
urban and highway stormwater runoff to meet US EPA water quality criteria or
worst-case numeric standards based on them is, therefore, not technically
appropriate and leads to over-regulation of chemical constituents in runoff
waters, and establishment of ineffective or unnecessary BMPs. It can also result in the failure to
identify real causes of water quality problems and in the overlooking of
contaminants that are, in fact, causing water quality problems. (Jones-Lee and Lee (2008) discussed
issues that need to be considered in regulating water quality impacts of
stormwater runoff; a copy of that paper is appended to these comments.)
The
US EPA has developed a procedure, the “water effects ratio,” to adjust the
national water quality criteria for site-specific conditions in an effort to
correct, to some extent, the overregulation of the application of
worst-case-based water quality criteria to many waterbodies. Unfortunately, the water effects ratio
only partially corrects the overregulation; potential pollutants in some sources
such as urban and highway stormwater runoff are in chemical forms that behave
differently than the 100%-available forms used in the US EPA water-effects-ratio
adjustment. This can cause the
adjusted value to also substantially over-regulate contaminants in these types
of discharges. Lee and Jones-Lee
have developed several reviews on the deficiencies in the monitoring approaches
that are typically used by stormwater runoff water quality managers but often
required by regulatory agencies (including Lee and Jones, 1991, and Lee,
2002).
“Evaluation Monitoring” for Stormwater
Runoff
In the mid-1990s, Lee and Jones-Lee worked with
S. Taylor of RBF Consulting in Irvine, CA to evaluate the need for, and
appropriateness of, incorporation of conventional BMPs for stormwater management
in the development of a proposed toll road in the Upper Newport Bay area of
Orange County, California. The
primary concern was that the stormwater runoff contained several heavy metals in
concentrations above their worst-case-based national water quality
criteria. Such violations indicated
the potential that the heavy metals could be causing aquatic life toxicity in
receiving waters; conventional BMPs would have removed particulates, which
contained heavy metals.
Rather than following the conventional
monitoring approach of collecting grab samples of stormwater runoff and
analyzing them for a suite of potential pollutants such as heavy metals, they
obtained permission from the regulatory agencies to shift the emphasis to what
they call the “evaluation monitoring” approach described by Jones-Lee and Lee
(1998) and Lee and Jones-Lee (1999).
The evaluation monitoring employed measurement of toxicity in the runoff
instead of the conventional approach of measuring heavy metal
concentrations in the runoff and then trying to infer toxicity. This approach evaluates whether the
heavy metals, in combination with all other potentially toxic chemicals in the
runoff, are present in toxic amounts.
It was found that the stormwater runoff was toxic to Ceriodaphnia. However, as discussed by Lee and Taylor
(2001), contrary to what would have been surmised through conventional chemical
analysis, that toxicity was not due to heavy metals. Rather, further investigation revealed
that it was caused by pesticides used in urban and agricultural areas of the
Upper Newport Bay watershed, but that were not at that time routinely measured
in stormwater runoff.
The
conventional evaluation approaches would likely have measured total heavy
metals, found them to be “excessive” and in need of control, and triggered
construction of conventional BMPs such as detention basins or filters to remove
particulate heavy metals. This
would not have identified or addressed the real problem. The BMPs that were adopted in response
to the evaluation monitoring that was conducted included source control on the
use of pesticides that become part of the stormwater runoff. Not only did this provide more
appropriate pollutant control, it was also more cost-effective. The success of the evaluation monitoring
approach in the Upper Newport Bay watershed has caused Lee and Jones-Lee to
recommend that stormwater runoff water quality managers and regulatory agencies
shift from the conventional monitoring of stormwater runoff to a site-specific,
focused effort to define the real, significant water quality impacts of urban
area and highway stormwater runoff.
This approach could serve as the basis for developing water quality
criteria/standards that are appropriate for stormwater runoff.
Further discussion of
the inappropriateness of regulating urban area and highway stormwater runoff
through application of the US EPA national water quality criteria is provided by
Lee and Jones-Lee (1998, 2000b) and Lee (1998). There is need to develop stormwater
runoff water quality criteria that will protect the designated beneficial uses
of waterbodies without significant overregulation of chemical constituents in
the runoff. While the US EPA has
proposed to develop wet-weather water quality criteria to address this need, the
agency has not devoted needed resources to this work in part due to opposition
to this approach by environmental groups.
Recommendation
There is need to
develop wet-weather criteria/standards that properly reflect the coupling
between critical concentrations of available forms of potential pollutants and
duration of organism exposure that is characteristic of stormwater runoff into
receiving waters. To provide
the technical foundation for such criteria/standards, stormwater runoff water
quality managers and the regulatory agencies need to fund representative,
comprehensive, evaluation monitoring studies to define the real, significant
impacts of runoff-associated chemical constituents in receiving waters.
Until this approach is
formulated and implemented, there will continue to be attempts by some
environmental groups to try to get regulatory agencies and/or the courts to
force public and private interests to fund stormwater runoff water quality
management programs to achieve worst-case-based national water quality
criteria/standards. Forcing such
compliance will be counterproductive to providing environmental quality
protection as it will result in the waste of funds for unnecessary and/or
ineffective treatment leaving fewer funds to address real water quality
problems. It would far more
effective for environmental groups to work with the technical community,
stormwater runoff water quality managers, and the public to develop a regulatory
approach that will protect the designated beneficial uses of the receiving
waters for runoff without significant unnecessary expenditures for chemical
constituent control. This should be
undertaken under the leadership of an expert panel knowledgeable and experienced
in the technical aspects of the nature and behavior of chemical contaminants in
urban and highway runoff as it enters receiving waters.
Other Sources of
Information
Discussions of Previous Court
Rulings. Stormwater Runoff Water Quality
Newsletter issues 9-6, 8-4, 5-3, 2-2, 1-5 (designations refer to
Volume-Number of the issues found at http://www.gfredlee.com/newsindex.htm)
provided background information on discharges of stormwater associated with
municipal, industrial, and construction activities, and to some of the past
litigation regarding compliance of urban stormwater runoff with water quality
standards. Newsletter Volume 2
Number 2, October 16, 1999 summarized the Ninth Circuit Court Ruling on Compliance with Water Quality
Standards. Newsletter Volume
5 Number 3, March 5, 2002 summarized the US EPA Appeals Board Decision,
Washington, DC, February 2002 Order regarding the need of the District of
Columbia’s municipal storm sewer system to comply with water quality standards
for urban stormwater runoff.
Newsletter Volume 1, Number 5,
January 30, 1999, discussed issues affecting the meeting of water quality
standards in urban stormwater runoff. Newsletter Volume 9, Number 6,
June 27, 2006 reviewed issues that need to be considered in developing water
quality criteria/standards for urban area and highway stormwater runoff to
control adverse impacts on water quality, and the efficacy of conventional “best
management practices” to meet water quality standards. It also provided information on an
expert panel report to the California State Water Resources Control Board
(SWRCB) entitled, “The Feasibility of Numeric Effluent Limits Applicable to
Discharges of Storm Water Associated with Municipal, Industrial and Construction
Activities.” Several other Lee and
Jones-Lee Stormwater Runoff Water Quality Newsletters have included information
on the application of water quality criteria/standards to urban stormwater
runoff, including Newsletter Volume 8, Number 4, August 12, 2005 that discussed
the Clean Water Act, water quality criteria/standards, TMDLs, and
weight-of-evidence approaches for regulating water quality.
Author's Bio: G. Fred Lee, Ph.D., P.E., DEE, is with G. Fred Lee & Associates in El Macero, CA. |
Author's Bio: Anne Jones-Lee, Ph.D., is with G. Fred Lee & Associates in El Macero, CA. |
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