Grantee Research Project Results
2000 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, 2000 through July 31, 2001
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 for a total economic benefit to the state of more than 27 billion dollars. To protect beach-goers 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 enterococci standard conforms closely to the national guidelines for marine water quality criteria published by the U.S. Environmental Protection Agency (Technical Report EPA-823/D-00-001). 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 U.S. Environmental Protection Agency 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 which 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 assembed 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 non-storm 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 near-shore region. In addition, strategies involving active passive control strategies to mitigate the impact of urban runoff were to be 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 to be interviewed or surveyed to evaluate preferences towards various objectives associated with active and passive control strategies. Subsequently, the decision model was to be 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 STAR award to better characterize this interaction. These efforts are
described below as Year 0, along with a report of STAR activities for Year 1.
Progress Summary:
Year 0. 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 near shore (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/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/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 near-shore.This 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 co-PI Grant and PI Sanders. Additional activities associated with this effort included the following:
- Dye studies conducted by Professor Burton Jones of the University of Southern California. These studies characterized the mixing of ebb flow from the Talbert Channel and Santa Ana River into the Huntington Beach surf zone, and provided insight into the effects of tides and waves on the nearshore mixing of water flushed from the Talbert and Santa Ana River Watershed by the tides.
- A nearshore hydrodynamic survey conducted by Moffat & Nichol engineers under contract with the City of Huntington Beach to characterize near-shore currents and waves. Acoustic doppler current profilers (ADCPs) 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 a duration of 1 month during May.
- A bird census conducted by the City of Huntington Beach concurrent with the May 2000, field monitoring effort. Video cameras were installed at several points within the Talbert Marsh to document the avian population and speciation on an hourly basis during daylight hours.
- A source survey conducted by URS Corporation, 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 analyzed for total coliform, fecal coliform, and enterococcus.
- Three offshore surveys conducted during May 2000, by the Orange County Sanitation District to evaluate 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.
- A network of oceanographic moorings were deployed between July 1999, and June 2000, by SAIC Corporation, under contract from the Orange County Sanitation District, to characterize 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.
- A soil and groundwater investigation was conducted by Komex/H20 Science in
May 2000, under contract from the City of Huntington Beach to evaluate 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.
Year 1. 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. Beginning in Year 0 and continuing through Year 1, 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. Close to 100 articles have been collected. In Year 1, we began to develop a survey that could be used to better understand these attitudes and opinions, so we may subsequently 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 utilized Year 1 to review physical and biological data that had been collected in Year 0, 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.
Year 0 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 buffer relative to one indicator of fecal pollution, Total Coliform (TC), but serves to amplify levels of another indicator of fecal pollution, Enterococcus (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 do represent a human health threat: campylobacter and salmonella. The samples are being collected by UCI personnel and are shipped to UNC for analysis.
Because the Talbert channel network and Talbert Marsh currently function to amplify ENT levels, another issue we began to address in Year 1 is whether a reversal of the function could be engineered through some modification to the hydraulics and/or ecosystem dynamics. At 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.
Year 0 monitoring of urban runoff was performed with a high sampling frequency (hourly) over a fairly short period of time (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 non-storm months in Year 1. 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.
To summarize, in Year 1 the research team was in a data gathering mode that was designed to complement other concurrent studies in the region surrounding the Talbert Watershed.
Future Activities:
In Year 2, we are moving from a data gathering mode to an analysis mode, though additional laboratory studies will be performed to better characterize processes that are important to the connections between: (1) watershed sources of microbial pollution and coastal water quality; and (2) indicators of fecal pollution and disease causing organisms. We also will continue with stakeholder surveys to obtain additional information that is needed for our decision analysis. An important issue that is arising from our investigation is that there appears to be tradeoffs between two national priorities: protecting coastal water quality and restoring coastal wetlands. This conflict was elucidated by our study of the Talbert Marsh, which is functioning to amplify ENT levels during non-storm periods. To address this issue, we are exploring engineering solutions to mitigate this functional aspect of coastal wetlands (e.g., designs that do not attract birds, enhancement of shellfish populations to improve filtering, changes to circulation that increase residence times). In addition, we are exploring the attitudes of stakeholder groups towards a coastal wetland ecosystem to evaluate, through decision modeling, how engineering solutions may or may not address all stakeholder objectives.Journal Articles on this Report : 2 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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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 |
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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, decision making, biology, engineering, social science, modeling monitoring, Pacific Coast., RFA, Scientific Discipline, Water, Geographic Area, Water & Watershed, Ground Water, 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.