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Comments Question Data in Criteria Used for Bacteria Standards Proposal
Questions on the data used to determine safe levels of bacteria in
recreational waters and the means of sampling those waters were raised in
numerous comments to the Environmental Protection Agency about a proposal
establishing standards for coastal and Great Lakes states.
EPA proposed July 9 the water quality criteria for bacteria in recreational
waters of coastal and Great Lakes states under the 2000 Beach Environmental
Assessment and Coastal Health Act. The comment period closed Aug. 9 (128 DEN
A-11, 7/6/04 ; 69 Fed. Reg. 41,720).
The standards would apply in the states that have not yet adopted EPA's criteria
reflecting an 1986 EPA document recommending ambient water quality criteria for
bacteria. Specifically, the document directs states to use E. coli instead of
fecal coliforms as an indicator of unsafe levels of fecal contamination fresh
water. Enterococci should be used as the indicator organisms for fresh and
marine waters.
The BEACH Act gave coastal and Great Lakes states until April 10 to incorporate
water quality criteria limiting bacteria concentrations to levels considered
safe enough for swimming based on EPA would have to set the criteria for the
four states failing to meet the mandate.
Wastewater treatment officials and representatives from scientific organizations
questioned the use of the 1986 criteria document because it relies on data that
is more than 20 years old.
The Association of Metropolitan Sewerage Agencies, for example, said the studies
used for the 1986 criteria document were flawed.
"AMSA has commented on the flaws in the original studies underlying the criteria
and the fact that no studies to confirm the criteria have been conducted since
they were first established," the comments said. "The 1986 enterococci
criterion, for example, was developed based on very limited and known to be
highly polluted U.S. coastal marine environments."
State agencies have raised similar concerns about the 1986 document (138 DEN
A-1, 7/20/04 ).
Sources of Contamination
Norm LeBlanc, chief of technical services for the Hampton Roads (Va.) Sanitation
District, said the studies done in the 1970s upon which the 1986 criteria are
based only looked at areas with fecal contamination known to come from human
sources such as combined sewer overflows. The studies did not consider areas
contaminated by birds, waterfowl, and other wildlife, LeBlanc said.
"Additionally, there were no control sites or beaches used. There were no sites
with natural sources of bacteria. There were clean sites without known point
sources of bacterial pollution," LeBlanc said.
Other groups also commented on the fact that the proposed criteria do not
consider other sources of contamination nor do they consider human health
impacts other than gastrointestinal illness.
The American Society for Microbiology said EPA should consider revising the
level of acceptable risk, which may have changed since the 1986 criteria were
issued. The risk level in the 1986 criteria is eight cases of gastrointestinal
illness per 1,000 swimmers in fresh water and 19 cases in marine waters. ASM
said the risk level should consider illnesses other than gastrointestinal
problems, such as respiratory sickness that can result from exposure to fecal
contamination.
ASM recommended the agency assess the reliability and use of the existing and
new indicator species, such as coliphages.
"In addition, the EPA should support detailed assessments of indicator species
ecology, particularly with respect to persistence and growth in receiving waters
and sediments," ASM said.
Other Criteria Needed
The Natural Resources Defense Council generally supported the proposal but urged
EPA to develop criteria for pathogen indicators that correlate with
contamination of recreational waters by viruses and other nonbacterial
pathogens. The criteria for E. coli and enterococci are superior to those for
fecal coliform, NRDC said, but do not serve as indicators for viruses that also
may contaminate recreational waters.
NRDC also opposed revising the level of acceptable risk from 0.8 percent to 1.0
percent, saying the proposal would statistically allow a 25-percent increase in
illness caused from swimming in contaminated water.
"Such a standard would thus not be 'as protective of human health' as EPA's 1986
304(a) criteria document, and thus would not be consistent with the requirements
of Section 303(i) of the Clean Water Act," NRDC said.
The head of the Milwaukee Metropolitan Sewerage District disagreed and said the
small increase in risk would have no effect on public health.
"It is doubtful that this increase would be significant in designated swimming
areas," Kevin Shafer, executive director of the district, said in comments. "In
water bodies with other use designations, this change would be even less
significant."
NRDC also said the agency should continue research into other methods of
measuring for contaminants.
"NRDC also encourages EPA to accelerate ongoing research into beachwater testing
methods for pathogens that can provide immediate results," Stoner said.
"Currently available tests usually take 24 hours or longer to provide results."
NRDC also said EPA should specify in the criteria that mixing zones, the areas
of initial dilution from a point source, should not be allowed.
"Use of mixing zones would not be as protective as the requirements in the 1986
water quality criteria document," NRDC said.
Geometric Mean, Single Sample Maximum
The 1986 criteria specifies a geometric mean, which EPA said is the best way to
assess risk over the course of a recreation season, and a single sample maximum
(SSM), which is the best value against which to compare individual measurements.
In the proposal, EPA said the use of SSM values would allow for a quantitative
determination based on a single sample of when water quality at a specific site
may be degraded.
"This is especially important for beaches that are infrequently monitored or
prone to short term spikes in bacteria concentrations," the proposal said.
Four single sample maximums, identical to the 1986 criteria, are proposed based
on the different types of recreational use of the water.
A geometric mean, which represents the central tendency of a series of bacteria
level measurements without giving too much weight to extreme values that may be
considered statistical outliers, is also proposed.
The proposal geometric mean for E. coli in fresh water is 126 colonies of
organisms per 100 milliliters.
The agency received significant comments regarding the use of the geometric mean
and single sample maximum, with many saying the latter should only be used
regarding decisions on whether to close a beach because of excessive bacteria
levels. The SSM should not be used for regulatory compliance purposes, such as
National Pollutant Discharge Elimination System permit limits, several
wastewater treatment officials said.
Erwin Odeal, executive director of the Northeast Ohio Regional Sewer District,
said the use of an SSM is more protective than what is mandated in the BEACH
Act.
"Adopting the SSM as a value never to be exceeded could, in practical
implementation, have the undesired effect of discouraging the collection of
sufficient samples to calculate a representative geometric mean--the indicator
of human health risk acknowledged by EPA to be much superior to individual
values from single samples," Odeal said.
Alton Boozer, chief of the Water Bureau for the South Carolina Department of
Health & Environmental Control, was among those who said EPA should include both
the geometric mean, which should be used as a chronic number in water quality
programs, and the single sample maximum for the acute number in the criteria.
However, states should have the flexibility to determine which single sample
maximum should be used in which waters, he said.
"We know South Carolina's Grand Strand has extremely high use and the SSM should
reflect that," he said. "However, Gulf Coast beaches in Mississippi and Alabama,
perhaps the most heavily used in their states, do not receive nearly the use as
the Grand Strand. Accordingly, they should have an SSM to reflect that in
comparison to the most heavily used beaches in the region or nation."