Water quality information collected by local officials may provide increased beach access while minimizing swimming-related illnesses from harmful bacteria, according to a new U.S. Geological Survey study authored by a local scientist at the USGS Lake Michigan Ecological Research Station in Porter.

The USGS study found that current water quality testing at Great Lakes beaches may be applied too broadly, possibly resulting in as many as 681 more Chicago-area beach closings between 2004 and 2010 than may have occurred if a more localized approach was taken, according to a statement released by USGS on Tuesday.

“Recent studies have determined that closure of Great Lakes beaches to recreational use represents significant economic losses that are compounded if all beaches in one area are simultaneously closed down,” USGS director Marcia McNutt said. “Any time that science can be used to prevent unnecessary closures such that human health is still protected and the economy doesn't needlessly suffer, everyone wins.”

The commonly applied federal health study guidelines, set forth by the U.S. Environmental Protection Agency, were based on studies conducted at beaches directly affected by sewage contamination, the study notes, and although “the EPA criteria provide flexibility for the use of local data, they are currently applied at all beaches when determining whether to close a beach or issue a swimming advisory, regardless of whether there is a sewage source.”

“By basing their beach closure decisions on local variations in bacteria concentrations, beach managers likely will be able to keep their beaches open more often, without increasing the presumed health risk or violating the EPA guidelines,” said Meredith Nevers, a scientist with the USGS Lake Michigan Ecological Research Station and the study’s author. “Our goal is to make local beach managers fully aware of the flexibility that the EPA is providing in its current guidelines.”

The USGS study examined historic monitoring data from 50 Lake Michigan beaches in Illinois and Indiana. New calculations using local monitoring results for the 50 sites indicated that the current applications may be more conservative than necessary for these and most coastal beaches across the country.

The EPA is expected to release new recreational water quality criteria in October 2012 which, like the current guidelines, will apply to all coastal marine and Great Lakes beaches.

This USGS Great Lakes Science Center research was funded by the USGS Ocean Research Priorities Plan and the Great Lakes Restoration Initiative.

The article is published in the journal Environmental Science and Technology.