Yahara Portal

Explore the legacy and future of the Yahara Lakes and Watershed

Bacteria

Outbreaks of bacteria routinely cause the closing of City of Madison beaches during the summer, resulting in the loss of recreational opportunities as well as economic and social value to residents. The EPA has a health standard for E. coli, the bacterium it uses to measure beach health. If the geometric mean is greater than 235 colony forming units/100 milliliters, the beach is closed.

The Public Health-Madison and Dane County (PHMDC) collects samples from knee deep water and uses a higher single sample beach closure threshold (E. coli > 1000 MPN/100mL (1000 Most Probable Number/100 milliliters)) for bacterial beach water quality at Madison beaches. This level is based on several decades of experiences in beach monitoring, knowledge of the depth distribution with significant bacterial decline with depth and the general contaminant sources as well as lack of evidence of occurrence of swimming related illness below that level. Furthermore, Madison beaches do not receive point-source contamination.

The analysis of bacterial samples historically takes 24 hours to complete, causing beach managers to always be a day behind in decision-making. This means that often beaches stay open on the first day of a bacterial outbreak or may be closed on days after bacterial counts have decreased. Research scientists are making progress on developing tests for rapid response monitoring to make a more immediate decision on whether or not the beach should be closed. Lifeguards are also able to make a visual assessment of the beach and identify blue-green algal blooms which may cause serious health effects.

In 2008, review of the beach bacteria data collected by the City of Madison led to the listing of 9 of 13 of its beaches as impaired because of exceeding the health standard. The city collected additional data in 2010 and as a result of additional testing, three of the nine beaches were no longer considered impaired. Those that do not meet water quality standards are Vilas Beach on Lake Wingra, and the remainder on Lake Monona: Olbrich Beach, Olin Beach, Ester Beach, Bernie’s Beach, and Brittingham Beach.

As part of the Yahara CLEAN project, the following recommendations were presented to address the issue of beach contamination

  • Comprehensively evaluate potential pollution sources at beaches (the EPA-developed Beach Sanitary Survey is an excellent tool) and develop a beach master plan. Reducing impacts from urban geese is a key component of implementation.

  • Create a beach group involving all stakeholders and jurisdictions to foster political will and funding resources to achieve goals. Recognize the importance of education in informing and advancing public and political will.

  • Recognize that healthy, sustainable beaches have social, political, and economic value.

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