Legionella- How Big is a Threat to Groundwater under High Recharge Conditions (ASUF 30005948)

Project: Research project

Project Details


Legionella- How Big is a Threat to Groundwater under High Recharge Conditions (ASUF 30005948) Legionella- How Big is a Threat to Groundwater under High Recharge Conditions? Statement of Problem and Research Objectives Under the Groundwater Management Act (GMA) of 1980, five Active Management Areas (AMAs) have been created and Phoenix is among one of those AMAs. One of the founding principles of the GMA is to bring the focus areas into Safe Yield. Safe Yield is defined as the balance between groundwater withdrawal and natural and/or artificial recharge. Given the finite water and a growing population, central Arizona has to excessively rely on groundwater recharge. The Central Arizona Groundwater Replenishment District (CAGRD) is required to analyze potential risk associated with recharge facilities that may be used by CAGRD for replenishment. Arizona is one of the leading states practicing groundwater recharge to meet current and future water needs; however, substantial recharge practices have their own caveat. The possibility of contaminant mobility from surface water to ground waters is presumed to increase with the high recharge rates. In addition, contaminant transport risk further multiplies under stresses caused by climate change, another significant factor in management of water resources in the valley. Legionella is frequently detected in reclaimed water, surface water, and treated municipal water. In a study performed in California, Legionella were present in reclaimed water at all five locations tested, with three of the five locations registering L. pneumophila in 11-40% of Legionella-positive samples (Palmer et al. 1993a). In a subsequent study, L. pneumophila was detected in 5 of the 16 sites (Palmer et al. 1993b). Surface water receiving chlorinated effluents are reported to test positive for Legionella species in more than 90% of the samples tested and the average concentration of Legionella was 103 cells per ml. It is pertinent to point out that Legionella species particularly L. pneumophila, are responsible for more drinking water and non-recreational water-borne disease outbreaks in the United States than any other microbe (Brunkard et al., 2011). Recently, Legionella was added to the EPAa candidate contaminant list (CCL) (EPA 2009).. Incidence of legionellosis has consistently and significantly risen (Hicks et al., 2011) since the discovery of the disease in 1976 (Fraser et al., 1977). Over the last several years we have studied Legionella survival and incidence in water resources and structures across the valley and have found high incidence rate of this bacterium in water infrastructures (ranging from distribution systems to hot groundwater wells) (Scwake, et al., 2012).In addition, legionella survival experiments performed by our group indicate that certain components in environmental water, including some potentially dissolved in the waters, are capable of supporting the growth of this pathogen (Scwake, et al., 2013). Information collected by our group and reported by others need to be considered in conjunction with the aquifer characteristics and specific water management practices employed in the valley. Nexus of these factors (proven to be important individually) highlights the need for studying the transport potential of Legionella mobility and survival under these conditions. The proposed study will investigate the occurrence of Legionella and the transport through aquifer under conditions relevant to Central Arizona.
Effective start/end date1/1/1412/31/14


  • Arizona State University Foundation (ASUF): $46,000.00


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