Environmental and Social Impact of Stormwater Outfalls at Lake Michigan Beaches

Environmental and Social Impact of Stormwater Outfalls at Lake Michigan Beaches

Marcia Silva (University of Wisconsin-Milwaukee, USA) and Sandra McLellan (University of Wisconsin-Milwaukee, USA)
DOI: 10.4018/jsesd.2010070104
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Abstract

Milwaukee is the largest city in Wisconsin and home to approximately one million people. Lake Michigan waters in Milwaukee’s coastal area are mainly used for recreational purposes and drinking water. These coastal waters are impacted by many sources of pollution, from which the presence of sewage is a main concern, as this sewage contains numerous harmful pathogens. In this paper, the authors examine and analyze the beaches of Milwaukee for pollutants to serve as an impetus for future action.
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Introduction

Milwaukee Metropolitan Sewerage District’s service area consists of 95% of separated sewers and 5% combined sewers. Separated sewer service areas have stormwater systems that collect surface runoff and discharge the stormwater directly to waterways untreated. Leaking or failing sanitary sewer infrastructure may allow human sewage to enter the stormwater system. Under heavy rain events, there may also be sanitary sewage overflows (SSOs) and combined sewer overflows (CSOs) which discharge sewage into Lake Michigan.

Beach water and outfall samples from nine beaches in Milwaukee were monitored for Escherichia coli (E. coli), enterococci and the human Bacteroidales marker from 2006 to 2008. Almost all of the outfalls are from separated sewer systems, except one at South Shore Beach and one at Bay View Beach that discharge untreated sewage during heavy rain events when there are CSOs. McKinley is the only beach which outfall could not be sampled because it is located on a rocky area of the beach and it is of difficult access.

The geometric mean of fecal indicator bacteria in beach water samples during the study period ranged from 59 to 268 CFU/100 ml for E. coli and from 11 to 154 CFU/100ml for enterococci. Outfalls at all beaches were found to be positive for the human Bacteroidales marker at least once during the study period, except McKinley, where outfalls were not sampled. McKinley Beach was also the beach which presented the lowest E. coli and enterococci levels compared to the other beaches. Presence of outfalls at the beaches represents an environmental and societal concern since they may have a source of human sewage contamination, posing a human health risk.

In October 2000, a Federal Beach ACT was approved in the U.S. (U.S. Environmental Protection Agency, 2000). This Act declared that each State having coastal recreation waters would have to adopt water quality criteria and standards for the coastal recreation waters of the State for all pathogens and pathogen indicators to which the new or revised water quality criteria was applicable(U.S. Environmental Protection Agency, 2000). Since then, there was an increasing public awareness about the impact of fecal pollution to public beaches, since water quality advisories or closures occur when levels of fecal indicator bacteria exceeded standards set by individual State authorities (U.S. Environmental Protection Agency, 2003). According to the most recent National Resources Defense Council’s (NRDC) annual survey in 2008 (NRDC, 2008), the number of beach closings and advisories were their fourth-highest level in the 19-year history of the report. This may be due to increased testing at beaches, highlighting that previously, fecal pollution at beaches went unrecognized. The U.S. Environmental Protection Agency (EPA) requires that beaches be posted with an advisory sign informing the public of increased health risk when a water sample exceeds 235 colony-forming units (CFU) of E. coli per 100 milliliters of water and a closed sign when a water sample exceeds 1000 CFU/100ml.

Wisconsin became the first state in the U.S. to implement a beach monitoring program in accordance with federal program criteria, where counties test beaches up to four times a week for E. coli and inform swimmers about water quality conditions. Wisconsin has been praised by EPA as a model for other states (Wisconsin Department of Natural Resources, 2009).

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