Water Quality

Photo: Foster Avenue Beach, Chicago. Photo credit: Meredith Nevers, USGS.

Beaches across the nation are monitored for fecal indicator bacteria in an effort to protect humans from health issues associated with sewage contamination; when bacteria concentrations are out of compliance, swimming advisories are issued or beaches are closed to swimming. Closed beaches lead to frustration for beachgoers and economic losses for associated communities. While human health concerns outweigh these losses, new research indicates that beach managers may be unknowingly applying water quality regulations more stringently than was ever intended. Currently, most beach managers use a default single-sample standard as described in the water quality criteria even though it is recommended that managers calculate their own limit, based on typical fluctuations inherent at their beach and possibly based on sources of contamination. Use of this flexibility may help managers more accurately estimate the public health risk, often resulting in more open beaches without an increase in presumed health risk. As water quality criteria are currently under revision, more accurate estimates of water quality and human health risk would benefit beach managers and the public.

References:

• Nevers, Meredith B. and R.L. Whitman. In Press. Beach Monitoring Criteria: Reading the Fine Print. Environmental Science & Technology. doi 10.1021/es202568f.

For more information contact Meredith B. Nevers, Great Lakes Science Center.

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E. coli populations associated with Cladophora mats in Lake Michigan represent a mixture of stable and transient strains

Photo: Floating Cladophora mats in nearshore water at a southern Lake Michigan beach. . Photo credit:USGS

In the Great Lakes, massive accumulations of Cladophora mats are common along shorelines.   The high densities of E. coli and enterococci in the algal mats have been attributed to bacterial growth, as Cladophora provides an environment that is rich in nutrients and that offers protection from harmful sunlight.  In this study, using genetic techniques and statistical analyses, scientists from the Universities of Minnesota and Wisconsin – Oshkosh and the U.S. Geological Survey (Great Lakes Science Center, Lake Michigan Ecological Research Station) characterized the population structure of E. coli associated with Cladophora mats collected over multiple 3-day intervals from Lake Michigan during 2007-2009.  E. coli populations were highly diverse, consisting of unique strains and large clusters of identical strains; further, E. coli genotypes changed rapidly, even on a daily basis.  The current and related findings by these investigators are consistent with the hypothesis that Cladophora mats serve as an environmental source of indicator bacteria, such as E. coli, to Great Lakes beaches. 

For more information contact: Muruleedhara N. Byappanahali and Richard L. Whitman, Great Lakes Science Center, Dr. Brian Badgley and Dr. Michael Sadowsky, University of Minnessota.

Related Publication: Badgley, B. D., J. Ferguson, G. T. Kleinheinz, C. M. McDermott, T. R. Sandrin, J. Kinzelman, E. A. Junion, M. N. Byappanahalli, R. L. Whitman, and M. J. Sadowsky. 2010. Multi-scale temporal and spatial variation in genotypic composition of Cladophora-borne Escherichia coli populations in Lake Michigan. Water Research 45:721-731.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/20851450

Posted: March 11, 2011

USGS Scientist Katarzyna Przybyla-Kelly at a Lake Michigan beach collecting water sample that will be analyzed for enterococci using membrane filtration and quantitative PCR. Photo credit: USGS

Photo: amplification profile for enterococci using qPCR.  Photo credit: USGS

Recreational water quality is currently monitored for fecal indicator bacteria (E. coli or enterococci) to protect visitors from swimming-related illnesses such as gastroenteritis. Because the traditional culturing methods are time-consuming, often exceeding the rate of change for indicator bacteria, the U.S. EPA is currently revising the guidelines and considering the use of rapid methods (e.g., quantitative polymerase chain reaction qPCR) for indicator bacteria in beach waters. Recently, scientists with USGS examined the relationship between analytical outcomes using culture- and qPCR-based methods for enterococci in a variety of fresh and natural waters. Results indicated that the relationship was predictable but that the variation increased at lower concentrations of culturable enterococci. Overall, variation between samples was much higher for the qPCR-based results. Further research is needed to understand the relative contributions of analytical uncertainty, distribution and source of target bacteria, and antecedent environmental conditions.

See the project abstract:  Relationship and Variation of qPCR and Culturable Enterococci Estimates in Ambient Surface Waters Are Predictable

For more information contact Richard Whitman, Murulee Byappanahalli and Meredith B. Nevers.

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Photo: Microbiological Analysis - Membrane Filtration. Photo credit: Murulee Byappanahalli, USGS.

Photo: Water chemistry analysis. Photo credit: Murulee Byappanahalli, USGS.

Regulatory officials and beach managers need fast, reliable tests for analyzing the hygienic quality of beach waters.  In recent years, predictive modeling based on weather and ambient water conditions and quantitative PCR (qPCR) for enterococci have both been proposed as rapid analytical tools for testing beach water quality.  In this study, the two methods were analyzed in association with each other to determine if enterococci concentrations could be predicted using available ambient weather and water conditions.  Results indicated that enterococci counts measured by the current culturing method correlated with qPCR results, but different parameters were predictive of bacterial (enterococci) counts.  The combined use of these two rapid methods could reduce the current analytical time and increase affordability and accuracy of monitoring beaches for recreational use.

Citation:  Byappanahalli, M. N., R. L. Whitman, D. A. Shively, and M. B. Nevers. 2010.  Linking non-culturable (qPCR) and culturable enterococci densities with hydrometeorological conditions.  Science of the Total Environment 408(16):3096-3101 (doi:10.1016/j.scitotenv.2010.04.051).
Abstract: Available on-line (volume 408 (16); July 15, 2010) - Linking non-culturable (qPCR) and culturable enterococci densities with hydrometeorological conditions

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Masses of accumulated Cladophora washed onshore at a Wisconsin beach. Photo credit: USGS

Degrading Cladophora on the beach shore at a Chicago beach. Photo credit: USGS

Cladophora algae can form massive accumulations on Great Lakes beaches in the summer.  These algal mats are unsightly and malodorous, and recent research by USGS has identified high concentrations of fecal indicator bacteria and the presence of human pathogens.  Additionally, scientists have identified the presence of Clostridium botulinum in some algal mats and are exploring potential ecological links.  Researchers are investigating the community composition and the human health implications of these populations.

Fact Sheets:

• Algal (Cladophora) Mats Harbor High Concentrations of Indicator Bacteria and Pathogens (212 KB, PDF)
• Type E Clostridium botulinum May Grow In Great Lakes Algal Mats (208 KB, PDF)

References:

• Byappanahalli, M. N., R. Sawdey, S. Ishii, D. A. Shively, J. Ferguson, R. L. Whitman, and M. J. Sadowsky. 2009. Seasonal stability of Cladophora-associated Salmonella in Lake Michigan watersheds. Water Research 43:806-814.
• Byappanahalli, M. N., R. L. Whitman, D. A. Shively, J. Ferguson, S. Ishii, and M. J. Sadowsky. 2007. Population structure of Cladophora-borne Escherichia coli in nearshore water of Lake Michigan. Water Research 41:3649-3654.
• Whitman, R. L., D. A. Shively, H. Pawlik, M. B. Nevers, and M. N. Byappanahalli. 2003. Occurrence of Escherichia coli and enterococci in Cladophora (Chlorophyta) in nearshore water and beach sand of Lake Michigan. Applied and Environmental Microbiology 69:4714-4719.

Also contact Richard L. Whitman and Muruleedhara N. Byappanahali, Great Lakes Science Center.

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Putting soil in whirl pac. E. coli is commonly recovered in riparian forest soils of Dunes Creek along southern Lake Michigan. Photo credit: USGS

Exclosure in riparian forest soils of Dunes Creek. Photo credit: USGS

The presence of E. coli at the beach originating from nonpoint sources complicates its use as an indicator of microbiological water quality.  GLSC scientists are exploring the integrated stream and beach system to determine the influence of various nonpoint sources on beach contamination.  Upstream from the beach, forest soil contains high concentrations of E. coli.  These soils can be washed into streams that deliver bacteria directly to swimming water and elevate concentrations in water collected for beach monitoring programs.  Sources of E. coli may be wildlife, but bacterial concentrations are high even in the absence of direct fecal contributions from animals.  An understanding of how environmental factors interact with E. coli populations is important for assessing anticipated contaminant loading and the reduction of indicator bacteria in downstream reaches.  Scientists are examining bacterial source, flux, and context, within the dynamic lake and stream system to better understand how these processes may impact public health.

Related References:

• Byappanahalli, M., M. Fowler, D. Shively, and R. Whitman. 2003. Ubiquity and persistence of Escherichia coli in a midwestern coastal stream. Applied and Environmental Microbiology 69:4549-4555.
• Byappanahalli, M. N., R. L. Whitman, D. A. Shively, M. J. Sadowsky, and S. Ishii. 2006. Population structure, persistence, and seasonality of autochthonous Escherichia coli in temperate, coastal forest soil from a Great Lakes watershed. Environmental Microbiology 8:504-513.
• Whitman, R. L., M. B. Nevers, and M. N. Byappanahalli. 2006. Examination of the watershed-wide distribution of Escherichia coli along southern Lake Michigan: An integrated approach. Applied and Environmental Microbiology 72:7301-7310.
• Whitman, R. L., K. Przybyla-Kelly, D. A. Shively, M. B. Nevers, and M. N. Byappanahalli. 2008. Sunlight, season, snowmelt, storm, and source affect E. coli populations in an artificially ponded stream. Science of the Total Environment 390:448-455.

For more information contact Muruleedhara N. Byappanahali and Richard L. Whitman, Great Lakes Science Center.

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Fig 2.

Figure 1. Sampling frozen soil. Figure 2. Exclosure in snow. Photo credit: USGS

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Extracting DNA from water and sand samples for microbial source tracking. Photo credit: USGS

PCR gel for determining sources of fecal contamination. Photo credit: USGS

Microbial source tracking (MST) methods have recently been employed to identify reliable markers of human contamination.  An appropriate marker should be specific to human or animal sources, be present in the environment in detectable amounts, and be relatively easy to detect by PCR or culturing methods.  Much research has been done to develop methods that detect various host-specific molecular markers and to validate the specificity and sensitivity of the assays.  USGS scientists at Great Lakes Science Center have been investigating recently proposed human markers including Bacteroides and enterococcal surface protein esp gene.  The findings of these studies contribute greatly in the efforts to discover reliable, sensitive, and specific markers for detection of human pollution in microbial source tracking.

References:

• Byappanahalli, M. N., K. Przybyla-Kelly, D. A. Shively, and R. L. Whitman. 2008. Environmental occurrence of the enterococcal surface protein (esp) gene is an unreliable indicator of human fecal contamination. Environmental Science & Technology 42:8014-8020.
• Whitman, R. L., K. Przybyla-Kelly, D. A. Shively, and M. N. Byappanahalli. 2007. Incidence of the enterococcal surface protein gene in human and animal fecal sources. Environmental Science & Technology 41:6090-6095.

For more information contact Muruleedhara N. Byappanahali and Richard L. Whitman, Great Lakes Science Center.

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Deploying an ADCP to measure nearshore water conditions at an Indiana beach. Photo credit: USGS

USGS divers deploy an ADCP offshore from an Indiana beach. Photo credit: USGS

Beaches around the Great Lakes are monitored for fecal indicator bacteria (E. coli) to determine the presence of sewage contamination.  Traditional tests have proven to require more time than the rate of change of indicator bacteria concentrations, resulting in delayed notification of contamination or alternately unnecessarily closed beaches.  USGS scientists at the Great Lakes Science Center are exploring the use of predictive models to provide real-time estimates of microbiological water quality.  Using ambient hydrometeorological measurements, predictions of the concentration of fecal indicator bacteria are made, and beach managers can use this information for determining when to close the beach.  Timelier approaches will help to better protect public health.

Fact Sheets:

• New Approaches May Improve E. coli Monitoring for Beaches (201 KB, PDF)
• Studies of Indiana and Chicago Beaches Demonstrate Area-wide Understanding of E. coli Contamination (196 KB, PDF)

References:

• Nevers, M. B. and R. L. Whitman. 2005. Nowcast modeling of Escherichia coli concentrations at multiple urban beaches of southern Lake Michigan. Water Research 39:5250-5260.
• Nevers, M. B. and R. L. Whitman. 2008. Coastal Strategies to Predict Escherichia coli Concentrations for Beaches along a 35 km Stretch of Southern Lake Michigan. Environmental Science & Technology 42:4454-4460.
• Nevers, M. B., R. L. Whitman, W. A. Frick, and Z. Ge. 2007. Interaction and influence of two creeks on E. coli concentrations of nearby beaches: Exploration of predictability and mechanisms. Journal of Environmental Quality 36:1338-1345.
• Whitman, R. L. and M. B. Nevers. 2008. Summer E. coli patterns and responses along 23 Chicago beaches. Environmental Science & Technology 42:9217-9224.

For more information contact Meredith B. Nevers and Richard L. Whitman, Great Lakes Science Center.

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Collecting sand samples at an Indiana beach for analysis. Photo credit: USGS

Preparing sand samples to analyze for fecal indicator bacteria. Photo credit: USGS

Fecal indicator bacteria, such as E. coli and enterococci, can routinely be recovered from beach sand, often in higher concentrations than in the water column, which may indicate higher densities of human pathogens (bacteria, protozoa, and viruses).  The public health implications of these findings are important because beach visitors tend to spend a great deal of time in contact with sand.  Recent research by USGS has suggested that E. coli is persistent and ubiquitous in the sand in all seasons, and may even grow there under certain conditions.  Further, scientists found that the amount of E. coli accumulated through active contact with beach sand may reach up to 282 colonies on the fingertip alone, when exposed to highly contaminated sand.  However, rinsing hands once with water proved to be effective at removing most of the residual bacteria.  USGS scientists have been exploring nearshore dynamics involving transport and fate of bacteria in the swash zone to better estimate the risk and time of exposure to beachgoers. 

References:

• Byappanahalli, M. N., R. L. Whitman, D. A. Shively, W. T. E. Ting, C. C. Tseng, and M. B. Nevers. 2006. Seasonal persistence and population characteristics of Escherichia coli and enterococci in deep backshore sand of two freshwater beaches. Journal of Water and Health 4:313-320.
• Whitman, R. L. and M. B. Nevers. 2003. Foreshore sand as a source of Escherichia coli in nearshore water of a Lake Michigan beach. Applied and Environmental Microbiology 69:5555-5562.
• Whitman, R. L., K. Przybyla-Kelly, D. A. Shively, M. B. Nevers, and M. N. Byappanahalli. Accepted. Hand-mouth transfer and potential for exposure to E. coli and F+ coliphage in beach sand, Chicago, Illinois. Journal of Water and Health.

For more information contact Richard L. Whitman, Meredith B. Nevers, and Muruleedhara N. Byappanahali, Great Lakes Science Center.

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Visitors at Chicago’s 63rd Street Beach. Photo credit: Meredith Nevers, USGS

Swimming access is limited when E. coli concentrations in beach water are high. Photo credit: Meredith Nevers, USGS

Recent efforts to improve beach monitoring accuracy and timeliness have included the use of empirical predictive models. These models rely on fluctuations in ambient water and weather conditions to predict real-time estimates of water quality indicators (e.g., E. coli, enterococci), rather than the traditional, time-intensive culturing approach currently used in most monitoring programs.   While predictive models are being widely tested, assessments of their accuracy tend to focus on variation in E. coli (the biological indicator used in this study) explained by the model.  In the current study, USGS researchers examined whether predictive models could decrease the level of risk associated with swimming at 14 Chicago beaches.  Results indicated that individual beach predictive models were not necessarily more accurate than a comprehensive model that incorporated multiple beaches, but the use of an individual beach model, along with permissible relaxed standard criteria—per U.S. EPA recommendation—resulted in the most swimming access without any increase in presumed health risk. With upcoming changes in recreational water quality standards, monitoring alternatives will need to focus on improving public health protection through improved strategies.

References:

• Nevers, M.B. and R.L. Whitman. 2011. Efficacy of monitoring and empirical predictive modeling at improving public health protection at Chicago beaches. Water Research 45(4): 1659-1668.

For more information contact Meredith B. Nevers, and Richard L. Whitman, Great Lakes Science Center.

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