Search this site:

OWML: Completed Projects

Project Title: Rapid determination of E. coli concentrations at Lake Erie beaches using the IMS/ATP rapid method

Project chief:  Rebecca N. Bushon

Project support:  Amie M.G. Brady, and Robert A. Darner

Cooperators:  Northeast Ohio Regional Sewer District

Project duration:  2006-2009

Introduction and problem:
Current methods to determine concentrations of fecal-indicator bacteria require at least 18–24 hours from sample collection to availability of results. This time frame is too long to adequately assess the safety of the water based on recreational standards. Bacteria concentrations in the water can change overnight; and because results of the current day’s bacteria concentrations are not available until the following day, recreational users may be at risk of contact with water that has exceeded the standards and is not considered safe for recreation. Alternatively, the beach may be posted when the risk is low, resulting in lost recreational use and revenue. The need for a method to rapidly determine concentrations of fecal-indicator bacteria in recreational waters is widely recognized.

Goals and objectives:
The overall goal of the project is to identify a rapid method that provides beach recreational users with information regarding the current day’s E. coli concentrations. The specific objectives of this study are the following:

  1. Compare results of the IMS/ATP rapid method to the standard membrane-filtration method for E. coli at three Lake Erie beaches.
  2. Test the use of rapid-method results as a variable in predictive models and determine whether these results are better used in the predictive model or as a stand-alone variable.
  3. Determine whether analysis of a composite sample for E. coli is an accurate alternative to the current practice of analyzing two samples per beach and computing the mean.

The study took place at three Lake Erie beaches in Cleveland, Ohio—Edgewater, Villa Angela, and Huntington. Field studies were done during the recreational seasons of 2006 and 2007. Daily samples for E. coli were already collected as part of established monitoring programs. At Edgewater and Villa Angela, daily samples were collected by the Northeast Ohio Regional Sewer District (NEORSD) five times per week at two locations at each beach and analyzed in the NEORSD laboratory. At Huntington, daily samples were collected by the Cuyahoga County Board of Health (CCBH) four times per week at two locations and analyzed by the Cuyahoga County Sanitary Engineers (CCSE). All samples were analyzed for E. coli using the standard membrane-filtration method on modified mTEC media (U.S. Environmental Protection Agency, 2000). The study involved the addition of composite sampling, the testing of the IMS/ATP rapid method, and predictive model development.

A USGS Scientific Investigations Report documenting the results of this study is planned to be published in 2009.