Using a one-size-fits-all approach for bacteria testing may cause more Great Lakes beaches to close for health worries than warranted.
Federal law requires testing for E. coli at all recreational coastal waters so people don’t get sick. The EPA recommends using the local incidence of sickness and an average of the level of bacteria in local waters to establish an independent trigger for a closure. But most Great Lakes beach managers take a single sample and check if the level exceeds a general limit established by that federal agency 30 years ago.
A recent study published in Environmental Science and Technology found that these testing methods cause too many beach closings.
“Most management decisions are being overly conservative and not reflective of the true intention of the water quality standards,” said Meredith Nevers, research ecologist with the United States Geological Survey Lake Michigan Ecological Research Station.
The reason for too many closings is two pronged — the single sample method and the federal default limit for bacteria.
The federal limit is based on public health data at four beaches on two lakes. These studies were used to calculate the limit based on the variations in bacteria at those particular lakes. But in using the federal default, beach managers aren’t accounting for local variations.
That is why the EPA recommends beach managers establish their own limit based on health and bacteria data from their own beaches — it will allow them to know at what levels people are actually getting sick at their beaches.
Also, single samples are a snapshot of a specific time and can skew data by not accounting for day-to-day bacteria fluctuations.
This is especially true in places like Chicago, where non-point pollution sources — oil, grease and other urban runoff – cause water quality to vary dramatically.
Nevers studied data from approximately 50 beaches along the Lake Michigan coast in Illinois and Indiana.
She found that if local data were used to set the trigger there would have been 681 fewer Chicago-area beach closings from 2004 to 2010.
And Chicago is interested. Cathy Breitenbach, director of lakefront operations at the Chicago Park District, said Nevers’ study is news to a lot of beach managers in the region.
“Until Meredith’s study, I’m not sure many beach managers considered this (using local monitoring data) as a possibility,” Breitenbach said.
Breitenbach said she is unaware of anyone in the region who doesn’t use the EPA default standard. However, the park district is definitely interested in the study’s findings, she said.
“It’s a tricky topic, we want to be as protective as we can, but we don’t want to restrict swimming when we don’t have to … it’s a very delicate balance,” Breitenbach said.
Breitenbach said the park district is working with Nevers to predict water quality and would reevaluate their system after the EPA establishes new standards.
The EPA’s beach testing standards are vague. Even if beach managers wanted to develop their own monitoring data, there is no standard for how many years of data they should use or what nearby beaches they should include.
Widespread use of the EPA default can be traced to when beach monitoring started.
“When testing first started, few beaches had enough data to develop their own standards … you need monitoring data to calculate the single sample max,” said Shannon Briggs, toxicologist and beach monitoring coordinator at the Michigan Department of Environmental Quality. “The easiest thing for states to do was use the EPA standard.”
Michigan has its own maximum of 300 living E. coli bacteria per cup of water. Another reason for using the default is that changing a state’s water quality standard is difficult, Briggs said.
“When the criteria were first introduced, Michigan submitted the number to the EPA and had to get it approved,” Briggs said. “If we ever wanted to change it, we’d also have to get the Legislature involved.”
Nevers and colleagues have presented the findings to EPA officials with the hopes it will help guide the review process. By next October, the EPA must publish new beach water quality methods and criteria.
“We’ve talked to the EPA extensively about this, and in their stakeholder meeting on the upcoming criteria review they looked at this study,” Nevers said. “They really do want to address the original intentions and we hope they make it clearer.