State Water Resources Research Institute Program


Project ID: 2011AR317B
Title: Assessment of the microbial population in Beaver Lake swim beach regions to determine origin of fecal pollution
Project Type: Research
Start Date: 3/01/2011
End Date: 2/29/2012
Congressional District: 3
Focus Categories: Non Point Pollution, Water Quality, Recreation
Keywords: microbial source tracking, ultrafiltration
Principal Investigators: Gibson, Kristen Elizabeth; Ricke, Steven
Federal Funds: $ 21,003
Non-Federal Matching Funds: $ 42,012
Abstract: Numerous beach closure days occurred in the Beaver Lake reservoir located in Northwest Arkansas during the summer of 2010 due to elevated levels of generic Escherichia coli (i.e. > 126 cfu/100mL) detected in water samples. Elevated levels of E. coli - an indicator of potential human pathogens such as enteric viruses and protozoan parasites - could be a health risk to those using the lake for recreational purposes. In order to help prevent these closures from happening, identification of the primary origins/sources of fecal pollution is needed.

Current standard methods for the evaluation of microbial water quality - both recreational and finished drinking water - involve the use of generic bacterial indicators such as total coliforms, fecal coliforms, and E. coli. However, these indicator bacteria do not provide enough information to determine the source of the fecal contamination. In order to help prevent these closures from happening, identification of the primary origins/sources of fecal pollution is needed. By identifying the source, potential mitigation strategies may be better informed and directed. In addition, detection of these bacterial indicators rely on culture-based methods requiring a 24 hour incubation period which means the risk to public health was two days prior to the actual closure of the swim beach. Therefore, a more rapid and comprehensive approach to sampling susceptible swim beach areas needs to be developed to better protect recreational water users.

Recent advances in both microbiological and molecular methods can allow for the origin of fecal pollution to be determined with relative certainty. Here, we propose a year-long effort to collect, process, and analyze water samples from five of the nine beach regions in Beaver Lake across both Benton and Carroll counties in order to determine the dominate origin(s) of fecal contamination. In order to obtain representative data over time, filtration methods for the concentration of microorganisms from large-volume (60-100L) water samples will be applied. Collection of large-volume samples at select swim beach regions over a 12-month period will allow us to build a representative database, or "library", of microbial populations in Beaver Lake over multiple seasons. By doing this, we can provide information to help guide recommendations and policy for protection of the Beaver Lake reservoir from microbial insults which lead to degradation of water quality and swim beach closures. Moreover, there are 148 swim beach areas in the state of Arkansas; therefore, knowledge gained from this research will provide a basis for future research at other state drinking water reservoirs with similar swim beach closure issues. Because Beaver Lake reservoir is both a critical water supply for NWA and an economic asset, it is important that data collection be at the reservoir level and not extrapolated from published studies in other regions of the U.S.

Progress/Completion Report, 2011, PDF

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