Assessment of pathogen sources to Hook Pond, East Hampton, New York

 

In order to help identify sources of high Enterococci concentrations identified by the Village of East Hampton and the Surfrider Foundation’s water-quality sampling upstream of Hook Pond, surface water and groundwater samples will be collected and analyzed for F+-specific coliphage, bacteroides, Enterococci and fecal coliform, and nitrogen isotopes. Potential sources of pathogens include waterfowl, failing onsite wastewater disposal systems, and stormwater runoff. F+-specific colipahge (Griffin and others, 2000) and bacteroides (Stoeckel, 2005) analyses are sensitive microbial source tracking methods that can discern human, mammal, and bird sources. Nitrogen isotopes are used in conjunction with concentrations of nitrate or ammonium in surface water and groundwater and can help identify sources of nutrients that tend to coincide with animal waste or with human wastewater (Abbene, 2010). Collectively, these data will provide additional information related to the overall ecological health of Hook Pond.

 

 

Historical fecal indicator bacteria data will be evaluated for seasonal and spatial trends. A site visit will be conducted during a routine sampling field trip under the current Hook Pond water-quality assessment. Sample collection will be scheduled for the winter and spring during a routine visit. Samples would also be collected during a single storm event that coincides with a stormwater sample planned for the spring of 2018. A total of five sampling locations—two upstream of Davids Lane, north and south side of Davids Lane, Dunemere Lane, and Hook Pond water-quality sampling location—have been selected to track changes in concentration and type of bacteria and coliphage (figure 1). In order to assess the receptor (Hook Pond Dreen and Hook Pond) and the transport mechanisms (baseflow, stormwater runoff, groundwater seepage, waterfowl), the following methods will be employed.

 

1. Samples and field data will be collected during dry weather conditions in the winter (December 2017 or January 2018) and during wet and dry conditions in the spring (May or June 2018) seasons, using analytical methods for the following factors to develop a better understanding of the sources of pathogens and the relative proportions of host organisms. (Wet weather will be defined as 0.5 inch or more in 48 hours or 1 inch or more in 72 hours.)

  a. Fecal indicator bacteria: Enterococci and coliforms (total, fecal, and E. coli).

  b. F+ specific coliphage for both qualification (host specificity) and semi-quantification for relative loading calculations. These data will provide information on animal type based on four groupings and host-specific genetic markers (Griffin and others, 2000).

  c. Host-specific genetic marker analysis and archives: one-third of water samples will be analyzed (Stoeckel, 2005). Remaining water samples will be filtered and the filters will be frozen and stored for additional MST analysis using alternate source identifiers if necessary. Genetic markers would include those for cattle, human, dog, and waterfowl.

  d. Nutrients: inorganic forms of nitrogen and phosphorous for correlating with pathogen loading and necessary for nitrogen isotope analyses.

  e. Physical parameters: temperature, specific conductance/salinity, pH, dissolved oxygen, and turbidity.

  f. Weather conditions from available National Weather Service (NWS) stations and the nearby Maidstone Club.

  g. Stable isotope analysis.

    i. Nitrogen and oxygen isotopes from nitrate will provide additional source characterization for

    waters associated with nutrient and pathogen load: nitrogen isotope ratios provide insight into the

    process (nitrification) and sources (human, pet, fertilizer, atmospheric); oxygen isotope ratios

    provide insight into processes (nitrification, deposition, and (or) biological versus physical

    reduction/oxidation).

    ii. Nitrogen from ammonium will provide insight into the nitrogen source, particularly in

    groundwater with low dissolved oxygen that is impacted by wastewater (for example, fertilizer

    and (or) septic effluent)

2. Stormwater will be collected by grab samples at all locations and compared to the composite sampler collecting

wastewater indicators and nutrients as part of the current water-quality assessment.

3. Groundwater samples will be collected by drive-point piezometers along the shore at shallow depths (just below

to 5 feet below the water table) to provide insight into the sources of nutrients and related bacteria and virus

loading.

4. Quality assurance for the proper collection and handling of microbiological samples will be following according

to the USGS National Field Manual for the Collection of Water-Quality Data and documented in the interpretive

report. Quality controls samples will include a blank and a replicate for bacteria and coliphage; samples for

nutrients included in the ongoing water-quality assessment will be used for this study.