Grantee Research Project Results
2001 Progress Report: Identification and Control of Non-Point Sources of Microbial Pollution in a Coastal Watershed
EPA Grant Number: R828011Title: Identification and Control of Non-Point Sources of Microbial Pollution in a Coastal Watershed
Investigators: Sanders, Brett , Grant, Stanley B. , Sobsey, Mark D. , Horne, Alex , Keller, Robin
Institution: University of California - Irvine , University of North Carolina at Chapel Hill , University of California - Berkeley
Current Institution: University of California - Irvine , University of California - Berkeley , University of North Carolina at Chapel Hill
EPA Project Officer: Packard, Benjamin H
Project Period: August 1, 2000 through July 31, 2003 (Extended to January 31, 2005)
Project Period Covered by this Report: August 1, 2001 through July 31, 2002
Project Amount: $895,234
RFA: Water and Watersheds (1999) RFA Text | Recipients Lists
Research Category: Watersheds , Water
Objective:
Beaches are an important part of the culture and economy in California. An estimated 550 million people visit California's public beaches annually, resulting in a profit of more than $27 billion. To protect beachgoers from exposure to waterborne disease, a new state law mandates the implementation of recreational water quality monitoring programs at public beaches with 50,000 or more annual visitors. Specifically, the law requires monitoring for total coliform (TC), fecal coliform (FC), and the enterococcus (ENT) groups of bacteria, all of which may indicate the presence of fecal contamination. The state also enforces a set of uniform standards for TC, FC, and ENT bacteria, including single-sample standards (10,000, 400, and 104 most probable number [MPN] or colony-forming units [CFU]/100 mL), and 30-day geometric mean standards (1,000, 200, and 35 MPN or CFU/100 mL); a lower single-sample standard for TC of 1,000 MPN or CFU/100 mL also applies when the TC/FC ratio falls below 10. The ENT standard conforms closely to the national guidelines for marine water quality criteria published by the U.S. Environmental Protection Agency (EPA). If indicator bacteria levels in the ocean exceed any of the above standards, the local health officer is required to either post signs that warn against swimming in the water, or close the ocean to the public if a sewage spill is suspected. The state standards and EPA guidelines are based on a series of epidemiological studies that link gastrointestinal illness and exposure to ocean water containing high levels of indicator bacteria, particularly ENT. The origin of ENT in these epidemiological studies was presumed to be anthropogenic sources of fecal pollution such as sewage, agricultural runoff, and urban runoff.
Huntington State and City Beaches in southern California have been heavily impacted by the passage of the new regulations. According to data provided by the Orange County Health Care Agency (OCHCA), there have been a total of 99 postings at Huntington State and City Beaches between July 26, 1999, when the bill went into effect, and September 5, 2000. Approximately 72 percent and 25 percent of these postings were triggered by violations of the ENT single-sample and geometric mean standards, respectively. Persistently high levels of indicator bacteria in the surf zone at Huntington State and City Beaches in the summer of 1999 led to an extensive survey of the local sewage infrastructure. No significant sewage leaks were discovered, prompting speculation that urban runoff from the nearby Talbert Watershed was a source of fecal pollution. The objectives and hypotheses for this Water and Watersheds study germinated prior to the beach closures, between 1997 and 1998. Preliminary analysis of historical monitoring data collected by the Orange County Sanitation District (OCSD) and OCHCA showed that indicator bacteria levels in the Talbert Watershed were higher than other monitoring stations along the coastline. Ultimately, a multidisciplinary team of investigators was assembled to:
· Characterize the spatio-temporal variability of microbial pollution in urban runoff and to identify the association between pathogens and indicator organisms.
· Develop a strategy to control the impact of urban runoff on the microbial water quality of coastal wetlands and beaches during nonstorm periods.
· Develop a multiple-objective decision model to aid stakeholders in selecting strategies to mitigate microbial pollution problems in coastal waters.
To achieve these objectives, a sampling survey of forebay water and channel water was proposed to ascertain the spatio-temporal variability of pathogens (enteric viruses) and indicator microorganisms (Escherichia coli, enterococci, spores of Clostridium perfringens, fecal coliform, and male-specific and somatic bacteriophage) present in the watershed, with the goal of ascertaining the association between pathogen levels and indicator organisms both at the inlet to the open channel waterways, and at the outlet where runoff drains to the nearshore region. In addition, strategies involving active passive control strategies to mitigate the impact of urban runoff were tested. Possible active control strategies included the regulation of hydraulic controls in the system, and passive control strategies included the use of constructed wetlands for bacteria and pathogen removal. For the decision model, stakeholders were interviewed or surveyed to evaluate preferences towards various objectives associated with active and passive control strategies. Subsequently, the decision model was applied to assess the efficacy of control alternatives and to identify previously unrecognized approaches for water quality control.
The beach closures that occurred in the summer of 1999, heightened interest among local governmental and resource agencies to better understand the relationship between watershed sources of microbial pollution and coastal water quality. As a result, additional funds were obtained prior to the start date of this research project to better characterize this interaction. These efforts are described below.
Progress Summary:
We conducted extensive field monitoring in the Talbert Watershed during 2-week periods in December 1999 and May 2000. These studies were designed to characterize the exchange of indicator bacteria between the watershed and the nearshore (December), as well as to evaluate how the Talbert Marsh functions to either amplify or dampen indicator bacteria levels (May). Water samples were collected from the Talbert Channel at a frequency of 1 per hour and analyzed for total coliform, E. coli, and enterococcus, as well as physical properties such as salinity and turbidity. In addition, hydrodynamic instrumentation was deployed in the Talbert Channel to characterize the dynamics of the tidal flushing. Instruments to measure water level, velocity, temperature, and salinity were installed at several points, and measurements were taken at a frequency of 12 per hour. The goal of these studies was to evaluate whether the elevated indicator bacteria levels in the surf zone at Huntington Beach could be explained based on watershed inputs of bacteria to the nearshore.
This University of California-Irvine (UCI)-lead investigation was one component of a greater effort to understand the causes of ongoing microbial contamination at Huntington Beach. This greater effort was coordinated by a local task force made up of personnel from the City of Huntington Beach, County of Orange, California Department of Parks and Recreation, Orange County Sanitation District, as well as university personnel including Project Investigators Brett Sanders and Stanley Grant. Additional activities associated with this effort included the following:
· Professor Burton Jones of the University of Southern California conducted dye studies that characterized the mixing of ebb flow from the Talbert Channel and Santa Ana River (SAR) into the Huntington Beach surf zone. They also provided insight into the effects of tides and waves on the nearshore mixing of water flushed from the Talbert and SAR Watersheds by the tides.
· Moffat and Nichol engineers conducted a nearshore hydrodynamic survey under contract with the City of Huntington Beach to characterize nearshore currents and waves using acoustic doppler current profilers (ADCPs). They were installed offshore of Huntington Beach and Newport Beach in roughly 6 m of water, just outside the surf zone. In addition, a directional wave gage and a tide gage were installed offshore of Huntington Beach. These instruments were deployed for the month of May.
· The City of Huntington Beach conducted a bird census concurrent with the May 2000 field monitoring effort. They used video cameras that were installed at several points within the Talbert Marsh. These cameras documented the avian population and speciation on an hourly basis during daylight hours.
· URS Corporation conducted a source survey under contract from the City of Huntington Beach, which involved sampling runoff at numerous points upstream of the tidal prism. Approximately 300 samples were collected from streets, parks, and channels, and were analyzed for TC, FC, and ENT.
· Three offshore surveys conducted during May 2000, by the Orange County Sanitation District, evaluated the potential for onshore transport of wastewater released 7 km offshore through an ocean outfall. Water samples were collected from a grid of stations surrounding the ocean outfall, and at each station, samples were collected every 5 m between the bottom and the surface.
· Between July 1999 and June 2000, SAIC Corporation deployed a network
of oceangraphic moorings, under contract from the Orange County Sanitation District.
This network characterized the coastal oceanography surrounding the OCSD outfall.
An ADCP and a chain of thermisters were deployed near the outfall, current and
temperature measurements were taken at multiple depths at a set of three moorings
along the 15 m isobath offshore of Newport and Huntington Beaches, and bottom
temperature was measured along a cross-shelf transect at three moorings between
the outfall and the 15 m isobaths.
· Komex/H20 Science conducted a soil and groundwater in May 2000, under
contract from the City of Huntington Beach. This investigation evaluated the
potential for fecal pollution in groundwater, possibly from a leaking sewage
infrastructure, to exfiltrate into the Huntington Beach surf zone.
These investigations provided useful insight into the dynamics of the microbial pollution in the Talbert Watershed and the Huntington Beach coastal zone. The resulting data are public information that are being utilized by the research team to better understand the complex relationships between people and wildlife, the watershed, the surf-zone, and the coastal ocean. However, the results of these investigations did not point to a single pollution source as the primary cause of the surf-zone water quality problems. Rather, it appears that several sources contribute to the poor microbial water quality at Huntington Beach, among these watershed sources from the Talbert Watershed.
Public interest in coastal water quality is very high in southern California, where the economy and lifestyle are closely linked to beach activities. Newspaper and magazine articles routinely report on coastal water quality investigations, agency efforts to improve coastal water quality, public concerns about coastal water quality, and public concerns and attitudes about agency efforts to investigate and improve coastal water quality. In the first year, and continuing into the second year, UCI researchers began to organize these articles to better characterize stakeholder groups, stakeholder attitudes and opinions, and how these groups, attitudes, and opinions change over time. Approximately 100 articles have been collected. In the second year, we began to develop a survey that could be used to better understand these attitudes and opinions, so we may formulate a decision model capable of characterizing the social consequences associated with various scientific and engineering solutions to coastal water quality problems.
The research team also reviewed physical and biological data that had been collected in the first year, to begin analyzing these data, to better focus the objectives of this project in light of these data, and to begin field and laboratory work in support of these objectives.
First year monitoring in the Talbert Watershed provided a much clearer understanding of the relationship between urban runoff and surf-zone microbial water quality than we previously had. One important insight gained from studies conducted in December 1999 and May 2000 (dry weather periods), is that the channel network, where flow is tidally driven, serves as a buffer relative to one indicator of fecal pollution, TC, but serves to amplify levels of another indicator of fecal pollution, ENT. The latter appears to be the result of avian fecal matter deposited on mudflats in the lower reaches of the Talbert Channel where the Talbert Marsh is located. Analysis of indicator bacteria levels in the surf-zone has shown that ENT is the indicator bacteria group primarily responsible for water quality violations, and ENT flushed from the Talbert Watershed appears to contribute to the high ENT levels near the outlet of the watershed.
If elevated surf-zone ENT levels are, at least in part, caused by avian fecal matter and not human fecal matter, it is not clear what the implications of a high ENT level are relative to human health. In our first year's field effort, we began a program to collect samples of bird feces from the Talbert Marsh and test these samples for the presence of organisms that represent a human health threat: Campylobacter and Salmonella. The samples are being collected by UCI personnel and are shipped to the University of North Carolina-Chapel Hill (UNC) for analysis.
Because the Talbert channel network and Talbert Marsh currently amplify ENT levels, another issue we addressed in the second year is whether a reversal of the function could be engineered through some modification to the hydraulics and/or ecosystem dynamics. At the University of California-Berkeley (UCB), research was initiated to explore the possibility that shellfish could serve to filter ENT from the water column. A survey of the shellfish in the Talbert Marsh was performed, and microcosm experiments were performed to examine ENT filtration rates associated with various native and commercially available shellfish. Experiments also were performed to determine the fate of the ENT within the shellfish.
First year monitoring of urban runoff was performed with a high sampling frequency (hourly) over 2 weeks. To better understand the variability of bacteria indicators and their relationship to a viral indicator, we performed weekly surveys of forebay and channel water quality over several storm and nonstorm months in the second year. Surveys were performed in forebays located in the upper portion of the watershed, where urban runoff slowly accumulates prior to discharging into the tidally influenced channel network. Indicator bacteria levels as well as the levels of a viral indicator, male-specific bacteriophage, were measured at several points over the depth of the forebay.
We also performed high frequency sampling over a 3-week period in the lower reaches of the Santa Ana River (SAR) Watershed. Because the SAR outlet is only a few hundred meters from the Talbert Outlet, both watersheds are linked to coastal water quality at Huntington Beach. The SAR investigation was funded by a consortium of public and private agencies, but personnel supported under the EPA grant participated in the field work. These additional investigations are proving to be tremendously useful for obtaining a system-scale understanding of microbial pollution dynamics in the coastal zone.
Research also was initiated to characterize the transport processes within the Talbert Channel system to better understand the volumetric exchanges that occur between the upper and lower portions of the watershed, and between the coastal zone. A hydrodynamic flow and transport model has been developed to assist in these tasks. The model provides insight into the hydraulic connectivity of the system. For example, we can understand the tidal conditions under which urban runoff may flush to the ocean in only a few hours, and other tidal conditions that lead to flushing times on the order of days.
At on onset of the third year, we organized a comprehensive dataset characterizing microbial pollution dynamics in the watershed, in the tidal wetlands connecting the watershed to the ocean, in the surf-zone, and in the coastal ocean. On the watershed side, a good understanding for the macroscale behavior of indicator bacteria had been developed from this dataset as is described under second year activities. However, we had yet to develop a sound understanding for indicator bacteria dynamics in the surf-zone or indicator bacteria dynamics offshore, in the vicinity of the Orange County Sanitation District's ocean outfall. Additionally, it remained unclear how ENT indicator bacteria were being amplified in the tidal wetlands, and whether there were connections between these bacteria and other organisms capable of causing human disease upon water contact. To address these gaps in our knowledge base, third year activities included the following:
· Brett Sanders is directing the analysis of the offshore oceanographic and indicator bacteria data to evaluate the possibility that wastewater discharged through the Orange County Sanitation District's ocean outfall was reaching the shoreline. This analysis highlighted a mechanism by which wastewater could be brought into the nearshore, internal tides, but the data did not show a continuous plume of wastewater between the outfall and the beach. Our findings were published in Environmental Science and Technology.
· Stanley Grant is leading the effort to understand the dynamics of indicator bacteria in the surf-zone. This allows us to develop surf-zone models that can be used to: (1) understand the regions of the surf-zone affected by watershed sources of indicator bacteria; and (2) identify regions of the shoreline where sources of fecal pollution exist, as well as the relative strength of these sources. Element 1 builds upon the well-known surf-zone transport models developed by D. Inman in the 1970s, and element 2 is designed as a means to use local monitoring data for the purpose of pollution source identification.
· Stanley Grant also is directing the effort to understand the mechanisms that amplify indicator bacteria levels in tidal wetlands. This involves analyses of water quality data collected in both the tidal wetlands within the lower SAR Watershed and the wetlands in the Talbert Watershed. It is possible that one or more of the following processes are contributing to the amplification of indicator bacteria in tidal wetlands: (1) avian fecal matter deposition; (2) bacterial growth in wetland sediments and subsequent exfiltration during falling tides; and (3) bacterial growth at the fluid-sediment interface and subsequent mobilization upon sediment suspension. Analyses are being conducted to better understand the relative importance of each of these possible factors.
· Brett Sanders is leading the effort to understand how wetland circulation, which is externally driven by the ocean tide but controlled locally by wetland topography, modulates the transport of point and nonpoint indicator bacteria sources to the surf-zone. We hypothesize that wetland topography is the most important factor controlling the impairment of the surf-zone by indicator bacteria that are amplified in tidal wetlands. The rationale for this hypothesis stems from the fact that: (1) residual circulation patterns are controlled by the topography; and (2) avian fecal matter deposition appears to be focused on intertidal mudflat areas, which are a feature of the topography. Using both field data collected in the Lower SAR and Talbert Watersheds, as well as model simulations, we are in the process of testing this hypothesis.
· Mark Sobsey is directing the effort to understand the linkages between indicator bacterial levels and pathogens. Samples of avian fecal matter have been collected at the field site and shipped to UNC so tests can be performed to examine whether Salmonella and Campylobacter bacteria and coliphages, organisms which can cause disease in humans, are present in avian fecal matter, in sediments, and/or in the water column.
· Both Stanley Grant and Mark Sobsey are coordinating an effort to identify the type of source that generated the fecal pollution (birds, humans, etc.). A subset of the water samples collected in the Lower SAR and Talbert Watersheds during June/July of 2001 were assayed for male-specific coliphage in co-PI Stanley Grant's lab at UCI, and samples testing positive were sent to co-PI Mark Sobsey's lab at UNC for serotyping. The serotyping procedure allows us to evaluate whether the origin of the bacteriophage is from a warmblooded human or a warm-blooded nonhuman source.
In the third year, Robin Keller directed a survey on the beach in Huntington Beach, asking beach-goers about their perspectives on the beach-going experience, including their reactions to beach pollution warning signs and the multiobjective utility to them of different beach activities. This component of the project is designed to advance our understanding of how to descriptively characterize the multiple attribute perspectives of stakeholders in an evolving environmental decision under risk. This research builds upon Robin Keller's work with Professor Monika Winn of the University of Victoria on StarKist's decision to stop fishing off the West Coast and on MacMillan-Bloedel's decision to alter forestry-harvesting practices. Both decisions involve stakeholders with widely divergent interests and the controversial problems that evolved into crisis decisionmaking situations.
Future Activities:
In the fourth year, we will continue with the data analysis and modeling begun in the third year. Our goal is to integrate all components of the project so as to develop: (1) a comprehensive understanding of indicator bacteria dynamics at the interface between urban watersheds and the coastal ocean; (2) the relationship between indicators and pathogens in this interface; (3) insight into strategies to modulate the surf-zone impact of pollution generated in this interface; and (4) an understanding of the public perception of bathing-water hazards and how this perception affects stakeholder decisions such as beach-goers' choices to swim in the presence or absence of warning signs or in the vicinity of channel outlets.
Journal Articles on this Report : 4 Displayed | Download in RIS Format
Other project views: | All 21 publications | 7 publications in selected types | All 7 journal articles |
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Type | Citation | ||
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Boehm AB, Sanders BF, Winant CD. Cross-shelf transport at Huntington Beach. Implications for the fate of sewage discharged through an offshore ocean outfall. Environmental Science & Technology 2002;36(9):1899-1906 |
R828011 (2001) R828011 (Final) |
Exit Exit |
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Chu AK, Sanders BF. Data requirements for load estimation in well-mixed tidal channels. Journal of Environmental Engineering - ASCE 2003;129(8):765-773. |
R828011 (2001) |
not available |
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Grant SB, Sanders BF, Boehm AB, Redman JA, et al. Generation of enterococci bacteria in a coastal saltwater marsh and its impact on surf zone water quality. Environmental Science and Technology 2001;35(12):2407-2416. |
R828011 (2000) R828011 (2001) R828011 (Final) |
not available |
|
Sanders BF, Green CL, Chu AK, Grant SB. Modeling tidal transport of urban runoff in channels using the finite volume method. ASCE Journal of Hydraulic Engineering 2001;127(10):795-804. |
R828011 (2000) R828011 (2001) |
not available |
Supplemental Keywords:
water, watersheds, marine, estuary, pathogens, viruses, bacteria, effluent, ecosystem, indicators, decisionmaking, biology, engineering, social science, modeling monitoring, Pacific Coast, geographic area, water, chemistry, ecology, engineering, environmental chemistry, epidemiology, hydrology, microbiology, state, wet weather flows, California, CA, active control, bacteriophage, clostridium, coastal watershed, decision model, enterocci, Escherichia coli, E. coli, fecal coliform, flood control, forebay water, indicator organisms, manmade wetlands, microbial pollution, nonpoint sources, pathogens, pollution identification and control, pump stations, recreational area, spatiotemporal variable, stakeholders, storm water, tidal influence, urban runoff., RFA, Scientific Discipline, Geographic Area, Water, Ground Water, Water & Watershed, Environmental Chemistry, State, Wet Weather Flows, Environmental Monitoring, Engineering, Watersheds, clostridium, pathogens, ecosystem modeling, fate and transport, coastal watershed, flood control, contaminant transport, suburban watersheds, bacteriophage, escherichia coli (e. coli), enterocci, man-made wetlands, urban runoff, decision making, runoff, pollution identification and control, recreational area, tidal influence, fecal coliform, decision model, microbial pollution, stormwater drainage, forebay water, non-point sources, water quality, California (CA), indicator organisms, stakeholders, active control, storm water, pump stationsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.