The Environmental Protection Agency on Nov. 26 revised its recommended water quality criteria for recreational waters, setting out measures to protect against gastrointestinal illness from fecal contamination.
The agency said the criteria if adopted by states into their water quality standards would promote rapid water testing, encourage early alerts to beach-goers, and protect against pollution after particularly heavy rainfalls. It covers all waters, including marine, estuarine, Great Lakes, and inland waters that are designated for primary contact recreation.
The new criteria replace criteria established in 1986 (21 DEN A-1, 2/2/12).
The revised criteria set out two sets of concentration thresholds for fecal bacteria--enterococci and e-coli--measured as the geometric mean of colony-forming units, or cfu, in monitored water quality samples. The agency said either set of concentration thresholds would protect the public from exposure to harmful levels of fecal bacteria and associated illness, while swimming, surfing, and engaging in other water contact activities.
The criteria also contain a backstop measure known as a statistical threshold value, or STV. That is a change from the 1986 criteria, which had no backstop measure.
States may use the recommended criteria to establish standards that either are identical to the criteria or are different, as long as they are scientifically defensible. The state water quality standards in turn form the basis for controlling the discharge and release of pollutants and for assessing the health of water bodies designated for fishing, drinking, and swimming.
The new criteria are based on several recent health studies and use a broader definition of illness than the 1986 criteria to recognize that symptoms may occur without a fever, including a number of stomach ailments, according to EPA. The agency also said it reduced from 90 days to 30 days the time period over which the results of monitoring samples may be averaged. That provides a more accurate assessment of the water quality for that time and allows for improved public notice about water quality, according to EPA.
EPA is recommending two options for meeting the fecal contamination threshold:
• a geometric mean of 35 colony-forming units of enterococci per 100 milliliters of marine and freshwater and a statistical threshold value of 130 colony-forming units per 100 mL, and a geometric mean of 126 colony-forming units of e-coli per 100 mL of fresh water and a statistical threshold value of 410 cfu per 100 mL.
•a geometric mean of 30 cfu of enterococci per 100 mL of marine and fresh waters and a statistical threshold value of 110 colony-forming units per 100 mL, and a geometric mean of 100 cfu per 100 mL with a statistical threshold value of 320 cfu per 100 mL.
The first option corresponds to a gastrointestinal illness rate of 36 cases in a population of 1,000, while the second option corresponds to a rate of 32 per 1,000.
The criteria that correspond to an illness rate of 36 cases per 1,000 correlate to water quality levels associated with the 1986 criteria, and that rate has a history of acceptance by the public, EPA said. The criteria that correspond to an illness rate of 32 cases per 1,000 would encourage an incremental improvement in water quality, it said.
The statistical threshold value serves as the backstop or the secondary level of concentration that EPA says must be met in order to protect the public health.
In a change from its proposal, EPA has recommended using a tighter statistical threshold value--the 90th percentile of the geometric mean of the samples for a particular water body--and said that no more than 10 percent of samples may exceed the statistical threshold value, “reducing the likelihood that high levels of bacteria from events such as strong rainfall will be missed.”
Initially, EPA had proposed using the 75th percentile of the geometric mean of the water samples as the STV, but now it is using that level as a beach action value, or the value at which beach advisories should be issued.
“The final criteria are more stringent compared with the proposal EPA put out,” Steve Fleischli, senior attorney for the Natural Resources Defense Council, told BNA.
For instance, Fleischli said, EPA agreed to set concentration thresholds, or indicator levels, based on a broader definition of an illness, which is not limited to gastrointestinal illnesses exhibiting a fever. EPA had limited itself in its 1986 criteria by only considering an illness rate based on symptoms that accompanied fever, but NRDC and others had objected strongly to maintaining the status quo in the revised criteria.
Chris Hornback, senior regulatory affairs director for the National Association of Clean Water Agencies, told BNA that he partially agreed with Fleischli that the criteria were more stringent in parts.
“We know that EPA went back and combed the data back and forth and came up with a second set of numbers that it could justify,” Hornback said.
Hornback said there would be a minor, incremental improvement in water quality from using one or the other recommended options because EPA has retained the geometric mean of 35 cfu per 100 mL for enterococci that it has been using. NACWA had urged EPA to retain that standard (214 DEN A-11, 11/6/12).
However, Fleischli expressed concern that “giving states the options to choose between criteria would lead to inconsistencies in water quality across states.”
The agency was under a consent decree to publish final criteria by Nov. 30 (Natural Resources Defense Council v. EPA, C.D. Cal., No. 06-4843, notice of extension 9/12/12; 207 DEN A-11, 10/26/12).
The 2012 Recreational Water Quality Criteria are available at http://water.epa.gov/scitech/swguidance/standards/criteria/health/recreation/index.cfm.
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