Faecal indicator organisms (FIOs) are major pollutants in many catchments world-wide, with streamside pastures on livestock farms being potentially significant sources. Hitherto, few empirical ...studies have quantified FIO fluxes from such areas or investigated streambank fencing (SBF) and other possible mitigation measures. The aim of this two-phase (before/after intervention) study of the effectiveness of SBF was to generate an empirical evidence-base to enable regulatory authorities to make better-informed decisions concerning the implementation of this measure. It was undertaken during the summer bathing season along a 271 m stream reach in the River Tamar catchment, SW England. The study included: cattle distribution surveys; monitoring of changes in E. coli (EC) and intestinal enterococci (IE) concentrations and fluxes down the reach and of concentrations in ditch flow and surface runoff; phage tracer studies of surface runoff from pasture land; and experimental streambed trampling to investigate streambed FIO sources. The results show that cattle spend a disproportionately large amount of time in the watercourse/riparian zone along unfenced streams; identify direct defecation to the stream by wading livestock and the release/mobilisation of FIOs from cowpats by surface runoff from the adjacent pastures at times of high flow as key transmission routes; and demonstrate that FIOs become incorporated within streambed sediments, from which they may subsequently be released by trampling. Partial exclusion of cattle through SBF with a drinking bay greatly reduces the time cattle spend in streams. Total exclusion SBF, with provision of an alternative drinking supply, considerably reduces FIO load inputs to the stream reach, e.g. at times of high flow, which are critical in terms of pollutant fluxes to coastal waters, the mean EC and IE input loads to the reach fell by 0.842 and 2.206 log10, respectively.
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•Unfenced streamside pastures are a significant FIO pollutant source in catchments.•Key FIO sources and transmission routes are investigated and quantified.•Streambank fencing is shown to reduce FIO inputs to streams by c. 1–2 log10.•Empirical data relating to other possible interventions are presented.
This paper explores ways in which the analysis of microbial data from routine compliance monitoring, in combination with basic environmental data, can provide insight into the factors affecting ...faecal-indicator organism concentrations in coastal waters. In the case study presented, eight designated bathing waters on the Fylde coast are continuing to exhibit unreliable compliance with the
Imperative standards for total coliform (TC) and faecal coliform (FC) concentrations specified in the EU Bathing Water Directive (76/160/EEC), despite significant reductions in geometric mean concentrations following recent major investment in the sewerage infrastructure. Faecal streptococci (FS) concentrations have remained high and have not been improved by the new sewerage schemes. The results suggest that, prior to the schemes, higher bacterial concentrations were strongly associated with rainfall; and sewage sources were important for TC and FC, but less important for FS, which may have been more strongly affected by diffuse catchment sources. In the post-schemes period, catchment sources appear to be of greater significance; rainfall remains as a significant, though less important, predictor; and tide height at time of sampling, together with variables such as sunshine and the proportion of onshore winds (which affect the survival and movement of bacteria that have already entered the coastal waters), assume greater significance. The approach used here provides a cost-effective management tool for the exploratory investigation of any monitoring point that is failing to meet recreational water quality standards.
Microbial source tracking techniques are used in the UK to provide an evidence-base to guide major expenditure decisions and/or regulatory action relating to sewage disposal. Consequently, it is ...imperative that the techniques used robustly index faecal indicator organisms (FIOs) that are the regulatory parameters for bathing and shellfish harvesting areas. This study reports a ‘field-scale’ test of microbial source tracking (MST) based on the quantitative PCR analyses of
Bacteroidales 16S rRNA genetic marker sequences. The project acquired data to test the operational utility of quantitative
Bacteroidales MST data, comparing it with FIO concentrations in streams, effluents and bathing waters. Overall, the data did not exhibit a consistent pattern of significant correlations between
Bacteroidales MST parameters and FIOs within the different sample matrices (i.e. rivers, bathing waters and/or effluents). Consequently, there was little evidence from this study that reported concentrations and/or percentages of human and/or ruminant faecal loadings (that are based on
Bacteroidales MST gene copy numbers) offer a credible evidence-base describing FIO contributions to receiving water ‘non-compliance’. The study also showed (i) there was no significant attenuation of the
Bacteroidales gene copy number ‘signal’ through the UV disinfection process; and (ii) single non-compliant samples submitted for
Bacteroidales MST analysis, do not reliably characterise the balance of faecal loadings due to the high variability in the MST signal observed.
At this stage in the development of the MST tool deployed, it would be imprudent to use the percentage human and/or ruminant contributions (i.e. as indicated by MST data acquired at a bathing water) as the sole or principal element in the evidence-base used to guide major expenditure decisions and/or regulatory action.
Constructed farms wetlands (CFWs) are increasingly being used to treat faecally contaminated ‘dirty waters’ from yard areas on livestock farms. The findings of the present study, undertaken at the ...Pwllpeiran experimental CFW, West Wales, provide empirical data on the effectiveness of CFWs in attenuating faecal indicator organism (FIO) concentrations and fluxes to the receiving waters to which they discharge; and insight into the extent to which attenuation rates are affected by retention times within the CFW and seasonal factors. Based on the maximum flows that a CFW is being designed to treat, an equation is developed to enable estimates to be made of the size of wetland required to achieve a desired level of FIO attenuation. Other aspects of CFW design to optimise FIO attenuation are considered, including the construction of frequent baffles (transverse ridges), leaving parts of cells unvegetated and incorporating an initial settling pond.
Faecal-indicator budget studies have shown marine bathing water quality at two small UK coastal resorts, Staithes and Newport, to be adversely affected by riverine inputs from lowland pastoral ...catchments (J. Chartered Inst. Water Environ. Mangt. 12 (1998) 414). The present paper reports on presumptive coliform (PC), presumptive
Escherichia coli (PE) and presumptive streptococci (PS) concentrations at 43 sampling points on watercourses within these catchments, and on their relationship with land use and livestock-related management practices, such as grazing and slurry/manure applications. The results show >10-fold elevations in geometric mean faecal-indicator concentrations under high-flow conditions, compared with low flow, with maximum high-flow geometric mean PC, PE and PS concentrations of 2.6×10
6, 1.8×10
6 and 4.4×10
5
cfu/100
ml, respectively. High-flow geometric mean concentrations exhibit highly significant positive correlations with land use/management variables associated with intensive livestock farming, both within the individual catchments and in the two combined. Additional factors, such as antecedent weather conditions and topography, contribute to inter-catchment variability in water quality. Although inputs from diffuse and point sources of pollution were not quantified, point sources (e.g. runoff from farm yards) seem likely to be significant. The findings suggest that it may be possible to develop generic statistical models to predict microbial water quality from land use and farm management data. They also provide indirect evidence that channel bed sediment ‘stores’ closely reflect land use within their catchments and that there is little die-off of organisms along watercourses.
Prediction of bathing water quality is recommended by the World Health Organization (WHO), the European Union (EU) and the United States Environmental Protection Agency (USEPA) and is an established ...element in bathing water management designed to protect public health. Most commonly, historical regulatory compliance data are used for model calibration and provide the dependent variable for modelling. Independent (or predictor) variables (e.g. rainfall, river flow and received irradiance) measured over some antecedent period are used to deliver prediction of the faecal indicator concentration measured on the day of the regulatory sample collection. The implied linked assumptions of this approach are, therefore, that; (i) the independent variables accurately predict the bathing-day water quality; which is (ii) accurately characterized by the single regulatory sample. Assumption (ii) will not be the case where significant within-day variability in water quality is evident. This study built a detailed record of water quality change through 60 days at a UK coastal bathing water in 2011 using half-hourly samples each subjected to triplicate filtration designed to enhance enumeration precision. On average, the mean daily variation in FIO concentrations exceeded 1 log
order, with the largest daily variations exceeding 2 log
orders. Significant diurnality was observed at this bathing water, which would determine its EU Directive compliance category if the regulatory samples were collected at the same time each day. A sampling programme of this intensity has not been reported elsewhere to date and, if this pattern is proven to be characteristic of other bathing waters world-wide, it has significance for: (a) the design of regulatory sampling programmes; (b) the use of historical data to assess compliance, which often comprises a single sample taken at the compliance point on a regular, often weekly, basis; and (c) the use of regulatory compliance data to build predictive models of water quality.
Field surveys were designed to examine the effects of sewage contamination from storm overflow effluent on faecal coliform and
Escherichia coli concentrations in the flesh of wild mussels (
Mytilus ...edulis). Bags containing 30 mussels each were fixed at known inter-tidal locations and retrieved at intervals following discharge from a nearby combined sewer overflow (CSO). Concentrations of faecal coliform bacteria and
E. coli were measured in the shellfish flesh and in samples of overlying water prior to collection of the mussel samples. Faecal coliform and
E. coli concentrations in shellfish increased rapidly after CSO discharge.
E. coli concentrations exceeded the European shellfish hygiene class C limit of 46,000 100
g
−1, and decayed during subsequent CSO discharge-free periods. The concentration and depuration response was independent of the magnitude of CSO spill volume. First-order exponential decay functions were fitted to the data. Decay rates were lower than those found in corresponding microcosm experiments. This relates to the repeated pattern of inundation and exposure associated with the tidal cycles in the estuary. Relationships between
E. coli and faecal coliform concentrations in the shellfish and overlying water samples were relatively weak (
r<0.60), a pattern often seen with data from uncontrolled environmental experiments.
Human adenoviruses (HAdV) may be implicated in some disease outbreaks associated with recreational water exposures, typically in swimming pools. Modern molecular methods can be used to detect HAdV in ...environmental water samples. During the EU FP6 Project VIROBATHE a database of over 290 HAdV analyses with corresponding faecal indicator organism (FIO) determinations was gathered and used to explore statistical associations between HAdV and FIO results. The FIOs measured were Escherichia coli, intestinal enterococci and somatic coliphage. Statistically significant trends of increasing proportions of HAdV-positive results in categories of increasing FIO concentration were found in freshwater but not seawater samples. The analysis of these trends in freshwater samples was refined, the trends remaining statistically significant when using categories of 0.5 log10 intervals of FIO concentration. Logistic regression models were then developed to predict the probability of a HAdV-positive outcome from FIO concentration. Potential applications of these models to predict the probability of HAdV-positive outcomes from routine FIO determinations used to describe recreational water quality exposures and to classify recreational water quality are discussed.
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► Over 290 samples were collected from diverse European freshwater and marine sites. ► Samples were analyzed for the presence of human adenovirus using PCR. ► Concentrations of traditional faecal indicator organisms (FIOs) were also measured. ► Adenovirus presence was relatively high at low FIO concentrations. ► Adenovirus presence increased with FIO concentration in freshwater samples.
In April 2001, draft ‘Guidelines’ for safe recreational water environments were developed at a World Health Organization (WHO) expert consultation. Later the same month, these were presented and ...discussed at the ‘Green Week’ in Brussels alongside the on-going revision of the European Union Bathing Water Directive 76/160/EEC. The WHO Guidelines cover general aspects of recreational water management as well as define water quality criteria for various hazards. For faecal pollution, these include faecal indicator organism concentrations and an assessment of vulnerability to faecal contamination. Central to the approach set out in the WHO Guidelines are: (i) the concept of beach profiling to produce a ‘sanitary inspection category’ which implies a priori hazard assessment as a core management tool and (ii) the prediction of poor water quality to assist in real time risk assessment and public health protection. These management approaches reflect a harmonized approach towards the assessment and management of risk for water-related infectious disease being applied by WHO. Numerical microbiological criteria for intestinal enterococci are proposed in the new Guidelines. These were developed using a novel approach to disease burden assessment, which has been applied to both recreational waters and urban air quality. This paper explains the scientific rationale and mathematical basis of the new approach, which is not presented in the WHO Guidelines for recreational waters.
Quantitative assessment of multiple sources to short-term variations in recreational water quality, as indexed by faecal indicator organism (FIO) concentrations, is becoming increasingly important ...with adoption of modern water quality standards and catchment-based water quality management requirements (e.g. the EU Water Framework Directive, Article 11 ‘
Programmes of Measures’ and the US Clean Water Act, ‘
Total Maximum Daily Loads’). This paper describes a study combining microbial tracers, intensive FIO measurement, open channel hydrology and molecular microbial source tracking (MST) to enhance understanding of recreational water quality at Amroth in southwest Wales, UK. Microbial tracers were released from four stream inputs during a moderate hydrograph event. Tracers from two local streams impacted simultaneously with a period of maximum FIO concentrations at the near-shore compliance monitoring site. Connection between these inputs and this site were rapid (9–33
min). Water quality impairment from a more remote stream input followed, 12.85
h after tracer release, sustaining FIO concentrations above desired compliance levels. MST analysis showed dominance of ruminant
Bacteroidales genetic markers, associated with agricultural pollution. This integration of tracers and MST offers additional information on the movement and individual sources causing water quality impairment.
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