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The microbiological quality of water has been a central focus for the United Nations family of agencies as they move from the Millenium Development Goals to the Sustainable Development Goals designed to reduce the burden of disease, often associated with poor microbial water quality, in many nations world-wide. This chapter first provides a guide to this major international effort which has reviewed and revised the global water quality agenda in this area. It then explains how UN agencies develop guidelines for microbial water quality. The recreational water quality guidelines are used as an example to illustrate how the science evidence-base is employed to design UN Guidelines that are often the starting point for nations and agencies, such as the European Commission, in defining legally enforceable water quality standards that employ the microbial parameters.

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.

To meet European Water Framework Directive requirements, data are needed on faecal indicator organism (FIO) concentrations in rivers to enable the more heavily polluted to be targeted for remedial action. Due to the paucity of FIO data for the UK, especially under high-flow hydrograph event conditions, there is an urgent need by the policy community for generic models that can accurately predict FIO concentrations, thus informing integrated catchment management programmes. This paper reports the development of regression models to predict base- and high-flow faecal coliform (FC) and enterococci (EN) concentrations for 153 monitoring points across 14 UK catchments, using land cover, population (human and livestock density) and other variables that may affect FIO source strength, transport and die-off. Statistically significant models were developed for both FC and EN, with greater explained variance achieved in the high-flow models. Both land cover and, in particular, population variables are significant predictors of FIO concentrations, with r2 maxima for EN of 0.571 and 0.624, respectively. It is argued that the resulting models can be applied, with confidence, to other UK catchments, both to predict FIO concentrations in unmonitored watercourses and evaluate the likely impact of different land use/stocking level and human population change scenarios.

Special Issue on proceedings of the Scottish Aquaculture: A Sustainable Future? Symposium, 21-22 April 2009, Edinburgh

The European Union Water Framework Directive requires that Management Plans are developed for individual River Basin Districts. From the point of view of faecal indicator organisms (FIOs), there is a critical need for screening tools that can provide a rapid assessment of the likely FIO concentrations and fluxes within catchments under base- and high-flow conditions, and of the balance (‘source apportionment’) between agriculture- and sewage-derived sources. Accordingly, the present paper reports on: (1) the development of preliminary generic models, using water quality and land cover data from previous UK catchment studies for assessing FIO concentrations, fluxes and source apportionment within catchments during the summer bathing season; (2) the calibration of national land use data, against data previously used in the models; and (3) provisional FIO concentration and source-apportionment assessments for England and Wales. The models clearly highlighted the crucial importance of high-flow conditions for the flux of FIOs within catchments. At high flow, improved grassland (and associated livestock) was the key FIO source; FIO loadings derived from catchments with high proportions of improved grassland were shown to be as high as from urbanised catchments; and in many rural catchments, especially in NW and SW England and Wales, which are important areas of lowland livestock (especially dairy) farming, ≥ 40% of FIOs was assessed to be derived from agricultural sources. In contrast, under base-flow conditions, when there was little or no runoff from agricultural land, urban (i.e. sewerage-related) sources were assessed to dominate, and even in rural areas the majority of FIOs were attributed to urban sources. The results of the study demonstrate the potential of this type of approach, particularly in light of climate change and the likelihood of more high-flow events, in underpinning informed policy development and prioritisation of investment.

Summer sampling of storm runoff generated from areas of roofs and hardstanding situated on four dairy/beef farms has provided novel information regarding its microbiological and chemical quality. All farm hardstandings generated runoff that was contaminated with respect to those pollutants (faecal coliforms, FC, and faecal streptococci, FS, major nutrients, organic carbon) that are ubiquitously associated with faecal matter and urine. The separate analysis of roof runoff indicated that these can contribute significant concentrations of FS, phosphorus (P) and potentially toxic elements such as zinc (Zn), and suggests a level of 'background' contamination originating from wash-off of bird droppings and in the case of Zn galvanised surfaces. On average hardstanding runoff showed enhanced concentrations of >4 orders of magnitude for FC and 2-3 for major nutrients and carbon relative to roof runoff. Organic forms of nitrogen (N) and P contributed significantly (averaging >40%) to the total dissolved fraction in both roof and hardstanding runoff. Part of the substantial variability in composition of runoff samples could be attributed to differences between farms as well as the timing of sample collection during individual storms. Where situations allowed, a comparison of water upstream and downstream of the farmyard demonstrated they acted as a source of multiple contaminants not only during hydrologically active storm events but also during dry periods. Contamination pathways included a combination of both point (e.g., septic overflows) and non-point (e.g., seepage from livestock housing) sources. Farmyards situated within intensive livestock farming areas such as SW Scotland, would be expected to have significant local and accumulated downstream impacts on the aquatic environment. Localised impacts would be particularly important for headwaters and low order streams.

Faecal indicator organisms (FIOs) are commonly used to quantify pollution of public health significance. Health protection, as indexed by FIO control, is a central aim of new ‘catchment-scale’ water quality management required in the USA by the Clean Water Act and in the European Union (EU) by the Water Framework Directive (WFD). Experience of the former, after a decade of implementation, suggests that the most significant reason for water quality ‘impairment’ is elevated FIO concentrations, mainly in recreational and shellfish harvesting waters. This provides an early warning of possible problems which the EU regulatory authorities are likely to face. To date, however, a surprising lack of EU attention has been given to prediction and control of catchment fluxes of this key parameter. This is likely to prove embarrassing if the experience of the US regulatory community is not acted upon with some urgency. There is a growing, though still partial, body of empirical science to form the ‘evidence-base’ for good regulatory practice. However, adoption of ‘best management practices’ (BMPs) to effect remediation of impacted waters will require close integration of water policy with policies on financial support for the farming community. This is likely to require enhanced communication and integration within the discrete policy communities addressing the agricultural sector through the Common Agricultural Policy and water regulation through the Water Framework Directive.

Some 1% of the UK population derives their potable water from 140,000 private water supplies (PWSs) regulated by Local Authorities. The overwhelming majority of these are very small domestic supplies serving a single property or a small number of properties. Treatment for such supplies is rudimentary or non-existent and their microbiological quality has been shown to be poor in every published study to date. Private water supplies serving commercial enterprises such as hotels, restaurants, food production premises and factories are more frequently treated and subject to closer regulation in the United Kingdom. As a result, it has been assumed that these larger commercial supplies are less likely to experience elevated faecal indicator and pathogen concentrations at the consumer tap which have been observed at small domestic supplies. This paper reports on intensive monitoring at seven commercial private water supplies (six of which were treated) spread throughout the UK serving hotels, holiday parks and food production enterprises. Daily sampling of ‘potable’ water, both at the consumer tap and using large volume filtration for Giardia and Cryptosporidium spp. was conducted over two six week periods in the spring and autumn of 2000. This allowed the effects of short term episodic peaks in faecal indicator and pathogen concentration to be quantified. All the supplies experienced intermittent pathogen presence and only one, a chlorinated deep borehole supply, fully complied with UK water quality regulations during both periods of sampling. Poor microbiological water quality typically followed periods of heavy rainfall. This suggests that the design and installation of such systems should be undertaken only after the likely range of raw water quality has been characterised, which requires a thorough understanding of the effects of flow and seasonality on raw water quality. There is no reason to suspect that the monitored sites are uncharacteristic of other commercial supplies and the results reinforce public health concerns related to domestic supplies. Furthermore, the pattern of contamination is highly episodic, commonly lasting only a few days. Thus, the relatively infrequent regulatory monitoring of such supplies would be unlikely to identify the poor water quality episodes and does not provide the data necessary for public health protection. Although some statistical relationship was found between faecal indicator organisms and the presence of pathogens, the use of FIOs in assessments of regulatory compliance may not always provide a reliable measure of public health risk, i.e. indicator absence does not preclude pathogen presence. The results of this study suggest that a risk assessment system similar to the WHO ‘Water Safety Planning’ approach might offer a more appropriate regulatory paradigm for private water supplies.

Parallel policy developments driven in the USA by the Clean Water Act and in Europe by the Water Framework Directive have focused attention on the need for quantitative information on the fluxes of faecal indicator bacteria in catchment systems. Data are required on point and diffuse source loadings, fate and transport of these non-conservative parameters, on the land surface, within soil systems, in groundwater, streams, impoundments and nearshore waters. This new information is needed by regulators to inform Total Maximum Daily Load estimates in the USA and Programmes of Measures in Europe both designed to prevent impairment of water quality at locations where compliance is assessed against health-based standards for drinking, bathing or shellfish harvesting. In the UK, the majority of catchment-scale activity in this field has been undertaken by physical geographers although microbial flux analysis and modelling has received much less attention from the research and policy communities than, for example, the nutrient parameters. This paper charts the policy drivers now operative and assesses the evidence base to support current policy questions. Finally, gaps and priority research questions are identified.

By 2015 all EU member states will need to have achieved the unprecedented condition of ‘good ecological status’ throughout their national watercourses. This means managing not only point sources of pollution, like sewage outfalls, but also diffuse sources such as runoff from farmland. The new quality requirements are set out in the 2000 European Water Framework Directive, the most significant piece of environmental legislation so far produced by the EU. This paper describes the new legislation, its timeline for implementation and the many technical challenges now facing regulators, engineers, social scientists and environmental professionals throughout Europe as a result.

The Ribble drainage basin is the single UK sentinel study area chosen for examining the implementation of the EU Water Framework Directive (WFD 20/60/EC). The study which has generated the data for this paper was initiated to quantify ‘catchment-derived’ fluxes of faecal indicators originating from both point and diffuse sources to inform the competent authorities on the potential for, and prioritization of, further options for reducing the faecal indicator loadings to this crucial coastal environment. It represents the first UK drainage basin-scale ‘profile’ of faecal indicator sources as recommended by WHO [1999 . Health Based Monitoring of Recreational Waters: The Feasibility of a New Approach; the “Annapolis Protocol”. World Health Organisation Geneva, Switzerland; 2003. Guidelines for Safe Recreational-Water Environments Volume 1: Coastal and Fresh-Waters. World Health Organisation Geneva, Switzerland] and incorporated into current drafts of the revised Bathing Water Directive [ Anon, 2004 . Council of the European Communities Amended proposal for a Directive of the European Parliament and of the Council concerning the management of bathing water quality. Brussels 23rd June]. This paper focuses on the relationships between land use and faecal indicator organism concentrations in surface waters within this very large drainage basin (1583 km2) containing some extensive urban areas. A geographical information system comprising readily available digital elevation, remotely sensed land cover and digital map data was used to generate the land use variables for subcatchments draining to 41 locations across the study area. Presumptive concentrations of coliforms, Escherichia coli and enterococci (colony forming unit (cfu) 100 ml−1) were measured at each location on at least 20 occasions over a 44-day period within the 2002 bathing season. The sampling programme targeted hydrograph events. Hydrometric records were used to allocate results as either base flow or high flow. At each site, geometric mean faecal indicator organism concentrations were significantly elevated at high flow compared to base flow. Stepwise regression modelling produced statistically significant models predicting geometric mean base and high-flow faecal indicator organism concentrations from land use variables ( r 2 : 49.5–68.1%). The dominant predictor variable in each case was the proportion of built-up land in subcatchments, suggesting that this land use type, with associated sewage-related inputs, is a critical source of faecal indicator organisms in this drainage basin.

Intestinal enterococci are the principal 'health-evidence-based' parameter recommended by WHO for the assessment of marine recreational water compliance. Understanding the survival characteristics of these organisms in nearshore waters is central to public health protection using robust modelling to effect real-time prediction of water quality at recreation sites as recently suggested by WHO and the Commission of the European Communities Previous models have more often focused on the coliform parameters and assumed two static day-time and night-time T90 values to characterise the decay process. The principal driver for enterococci survival is the received dose of irradiance from sunlight. In the water column, transmission of irradiance is determined by turbidity produced by suspended material. This paper reports the results of irradiated microcosm experiments using simulated sunlight to investigate the decay of intestinal enterococci in relatively turbid estuarine and coastal waters collected from the Severn Estuary and Bristol Channel, UK. High-turbidity estuarine waters produced a T90 value of 39.5 h. Low-turbidity coastal waters produced a much shorter T90 value of 6.6 h. In experiments receiving no irradiation, high-turbidity estuarine waters also produced a longer T90 of 65.1 h compared with corresponding low-turbidity coastal waters, T90 24.8 h. Irradiated T90 values were correlated with salinity, turbidity and suspended solids (r0.8, p0.001). The results suggest that enterococci decay in irradiated experiments with turbidity200 NTU is similar to decay observed under dark conditions. Most significantly, these results suggest that modelling turbidity and or suspended solids offers a potential means of predicting T90 values in 'real-time' for discrete cells of a hydrodynamic model.

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.

Aims: To characterize and model spatial variations in faecal-indicator organism concentrations in watercourses draining a large rural catchment during the bathing season. Methods and Results: Presumptive coliform (PC), presumptive Eschericia coli (PE) and presumptive enterococci (PEnt) concentrations were determined under base- and high-flow conditions at 24 monitoring points in the Rheidol/Ystwyth catchment, Wales. Relationships with land use and topographic variables within their ‘subcatchments’ were investigated. Geometric mean (GM) concentrations typically increase more than 10-fold at high flow. The proportion of improved pasture within subcatchments explains 81·6, 73·0 and 85·8%, respectively, of the variance in high-flow GM PC, PE and PEnt concentrations. Distributed modelling suggests that organisms derived from more distant parts of subcatchments may be lost through die-off and sedimentation along watercourses at base flow, although not at high flow. Reductions in concentrations are also evident downstream of reservoir impoundments. Conclusions: Large rural catchments may contribute substantially to faecal indicator loadings in coastal waters. Indicator concentrations can be modelled successfully using land use and topographic data. Significance and Impact of the Study: Development of a modelling approach that provides valuable insight into faecal indicator sources and the transport and survival of these organisms within large catchments.

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 x 10(6), 1.8 x 10(6) and 4.4 x 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.

Concern over nutrient levels and eutrophication in the north-east Atlantic sea area has required a reduction in inputs at several urban centres. Implementation of a best European Practice by the States of Jersey has necessitated an assessment of the impact of the Island's waste water treatment works (WwTW) on inorganic nutrient inputs to the coastal zone. Inorganic nutrient concentrations in stream and sewage effluent inputs into St. Aubin's Bay, Jersey, were monitored during the phytoplankton growing season. Inorganic nutrient input budgets were calculated using estimates of runoff based on hydrological data for an instrumented catchment. Results indicated that the WwTW accounted for 54% of the inorganic nitrogen load and 98% of the inorganic phosphorus load over the survey period. The remaining inputs from catchments are driven by the seasonality of flow and nutrient concentrations. Installation of nutrient removal technology at the WwTW would reduce the total inorganic nitrogen load by 33% and the inorganic phosphorus load by 86%. Implications for the WwTW and compliance with the European urban waste water treatment Directive 91/271/EEC are discussed.

Detailed epidemiological studies in the UK have shown a dose–response relationship between water quality and gastroenteritis experienced by bathers. Other predictors of gastroenteritis found in the studies provide comparative levels of risk attributable to, for example, certain types of food. The statistical distribution of faecal streptococci, based on log10 mean and log10 SD, is used to describe the exposure of the bathing population. The exposure distribution is used in combination with the dose–response relationship and other independent risk factors as a framework for a health-related “standards” system. The standard system defines a series of water quality thresholds which take into account variation in water quality. These categories could provide a basis for both “health-related” water quality objectives and advice to the public on potential health risks from bathing.

A series of investigations are underway which have quantified the contribution of faecal indicators delivered to nearshore coastal waters from the sewerage system and riverine inputs. Studies have been completed in Jersey, Staithes, Yorkshire, South Wales and the North-west. The research protocols have involved quantification of high and low flow faecal indicator delivery from the sewerage system and riverine sources as well as construction of nonpoint source models designed to predict faecal indicator delivery from diffuse, catchment sources. These investigations suggest a dynamic, but predictable, balance between inputs from the sewerage system and from 'catchment' sources. The sewerage system dominates during low flow conditions but is often overtaken by riverine inputs during high flow conditions after rainfall. Many bathing beach locations exhibit non-compliance after rainfall when stream inputs, rather than sewerage inputs, commonly dominate. The implications of this input pattern is that routine monitoring data may not provide information relevant to new infrastructure planning designed to achieve bathing beach compliance. This suggests that the present scientific information base is insufficient to underpin the extensive UK infra-structure investment programmes designed to ensure compliance with existing EU Directive 76/160/EEC standards. Furthermore, results to date, suggest that management attention must expand from its historical focus on infra-structure provision to incorporate diffuse sources of faecal indicator loading which present a new set of management and modelling challenges.

Water regulation world-wide is moving to a new and challenging paradigm characterised by integrated assessment and management of multiple pollution loadings within drainage basins. This is seen in the European Water Framework Directive and the United States Clean Water Act. Implementation lessons of the latter suggest the principal water quality concern at the continental scale is microbial pollution by faecal indicators and pathogens. This presents a major new challenge to the microbiological community and presents major opportunities of joint working with catchment scientists, modellers, engineers and the farming community. To date, very little catchment-scale science has addressed microbial flux measurement, modelling and prediction when compared to other parameters such as the nutrients, oxygen demand and sediments. The engineering community has made excellent progress on point-source pollution control from sewage works but, parallel progress on agricultural best management practices to limit diffuse-source pollution from agriculture is less evident and the science evidence-base for the efficacy of such measures remains equivocal. This contribution presents a clear set of research challenges and management priorities designed to stimulate further involvement by the microbiological community in this emerging area.

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.

The Water Framework Directive has caused a paradigm shift towards the integrated management of recreational water quality through the development of drainage basin-wide programmes of measures. This has increased the need for a cost-effective diagnostic tool capable of accurately predicting riverine faecal indicator organism (FIO) concentrations. This paper outlines the application of models developed to fulfil this need, which represent the first transferrable generic FIO models to be developed for the UK to incorporate direct measures of key FIO sources (namely human and livestock population data) as predictor variables. We apply a recently developed transfer methodology, which enables the quantification of geometric mean presumptive faecal coliforms and presumptive intestinal enterococci concentrations for base- and high-flow during the summer bathing season in unmonitored UK watercourses, to predict FIO concentrations in the Humber river basin district. Because the FIO models incorporate explanatory variables which allow the effects of policy measures which influence livestock stocking rates to be assessed, we carry out empirical analysis of the differential effects of seven land use management and policy instruments (fiscal constraint, production constraint, cost intervention, area intervention, demand-side constraint, input constraint, and micro-level land use management) all of which can be used to reduce riverine FIO concentrations. This research provides insights into FIO source apportionment, explores a selection of pollution remediation strategies and the spatial differentiation of land use policies which could be implemented to deliver river quality improvements. All of the policy tools we model reduce FIO concentrations in rivers but our research suggests that the installation of streamside fencing in intensive milk producing areas may be the single most effective land management strategy to reduce riverine microbial pollution.

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.

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.

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

Characterisation of faecal indicator organism (FIO) concentrations and export coefficients for catchments with particular combinations of land use and under specific climatic regimes is critical in developing models to predict daily loads and apportion sources of the microbial parameters used to regulate water quality. Accordingly, this paper presents a synthesis of FIO concentration and export coefficient data for the summer bathing season, with some comparative winter data, for 205 river/stream sampling points widely distributed across mainland UK. In terms of both geometric mean (GM) FIO concentrations and export coefficients (expressed as cfu km(-2) h(-1)), the results reveal (1) statistically significant elevations at high flow compared with base flow, with concentrations typically increasing by more than an order of magnitude and export coefficients by about two orders; (2) significantly higher values in summer than in winter under high-flow conditions; and (3) extremely wide variability between the catchments (e.g. four orders of magnitude range for GM faecal coliform concentrations), which closely reflects land use-with urban areas and improved pastures identified as key FIO sources. Generally, these two most polluting land uses are concentrated in lowland areas where runoff (m3 km(-2) h(-1)) is low compared with upland areas, which in the UK are dominated by rough grazing and forestry. Consequently, contrasts in export coefficients between land use types are less than for FIO concentrations. The GMs reported for most land use categories are based on 13 sites and exhibit quite narrow confidence intervals. They may therefore be applied with some confidence to other catchments in the UK and similar geographical regions elsewhere. Examples are presented to illustrate how the results can be used to estimate daily summer base- and high-flow FIO loads for catchments with different land use types, and to assess the likely effectiveness of certain strategies for reducing FIO pollutant loadings in areas with extensive areas of lowland improved pasture.

The importance of faecal indicator organism (FIO) fluxes within drainage basins is increasing as the European Union (EU) Water Framework Directive and the United States Clean Water Act place requirements on regulators to manage point and diffuse sources of microbial pollution causing non-compliance (EU) or impairment (US) of receiving waters. Central to this management task is knowledge of the likely FIO concentrations in raw sewage and treated effluents, but few empirical data have been published in the peer-reviewed literature. Accordingly, this paper presents results for 1933 samples from 162 different sewage discharge sites in the UK and Jersey, which encompass 12 types of sewage-related discharge, representative of untreated sewage and primary-, secondary- and tertiary-treated effluents. Geometric means (GMs) and 95% confidence intervals (CIs) have been used to characterise base- and high-flow FIO concentrations. The data sets and sub-sets are mostly quite large (n 40) and may therefore be applied with some confidence to comparable discharge sites in similar geographical regions. Very marked, statistically significant reductions in GM FIO concentrations result from secondary and tertiary treatment, and there are statistically significant differences between some secondary and some tertiary treatments. Flow conditions are also shown to be important: untreated sewage and effluent from primary treatment plant have lower concentrations at high flow, due to dilution within combined sewerage systems, whereas some treated effluents (e.g. from activated sludge plant) have higher concentrations at high flow because of the shorter residence time within the plant. Under base-flow conditions, secondary treatments result in estimated GM FIO reductions of 95.22-99.29% (cf. primary-treated effluent). Corresponding figures for tertiary treatment plants (cf. secondary-treated effluent) are 93.24-96.59% for reedbed/grass plots and 99.71-99.92% for UV disinfection. Results suggest that secondary and tertiary treatment plants are less effective under high-flow conditions, but further high-flow sampling is required to confirm this.

Under the EU Water Framework Directive (WFD) 20/60/EC and the US Federal Water Pollution Control Act 2002 management of water quality within river drainage basins has shifted from traditional point-source control to a holistic approach whereby the overall contribution of point and diffuse sources of pollutants has to be considered. Consequently, there is a requirement to undertake source-apportionment studies of pollutant fluxes within catchments. The inclusion of the Bathing Water Directive (BWD), under the list of 'protected areas' in the WFD places a requirement to control sources of faecal indicator organisms within catchments in order to achieve the objectives of both the BWD (and its revision - 2006/7/EC) and the WFD. This study was therefore initiated to quantify catchment-derived fluxes of faecal indicator compliance parameters originating from both point and diffuse sources. The Ribble drainage basin is the single UK sentinel WFD research catchment and discharges to the south of the Fylde coast, which includes a number of high profile, historically non-compliant, bathing waters. Faecal indicator concentrations (faecal coliform concentrations are reported herein) were measured at 41 riverine locations, the 15 largest wastewater treatment works (WwTWs) and 15 combined sewer overflows (CSOs) across the Ribble basin over a 44-day period during the 2002 bathing season. The sampling programme included targeting rainfall-induced high flow events and sample results were categorised as either base flow or high flow. At the riverine sites, geometric mean faecal coliform concentrations showed statistically significant elevation at high flow compared to base flow. The resultant faecal coliform flux estimates revealed that over 90% of the total organism load to the Ribble Estuary was discharged by sewage related sources during high flow events. These sewage sources were largely related to the urban areas to the south and east of the Ribble basin, with over half the load associated with the relatively small subcatchment of the River Douglas. The majority of this load was attributed to two WwTWs that discharge through a common outfall close to the tidal limit of this catchment. Budgets adjusted to accommodate the impact of proposed UV disinfection of these effluents showed that the load from these sources would be reduced significantly during base flow conditions. However, during high flow events loads would still remain high due to the operation of storm sewage overflows from stormwater retention tanks. The study identified untreated storm sewage spills from urban infrastructure and WwTW stormwater retention tanks as the dominant component of the high flow flux of faecal indicators to receiving waters of the Fylde coast and the associated bathing waters.

The contribution addressed reveals an optimistic design philosophy likely to systematically underestimate risk in epidemiologic studies into the health effects of bathing water exposures. The authors seem to recommend that data on the ‘exposure’ measure (i.e. water quality) in such studies should be acquired in a similar manner to that used for regulatory sampling. This approach may compromise the quality of the epidemiologic investigations undertaken. It may result in imprecise estimates of exposure because it ignores the fact that regulatory timescales and spatial resolution (even if artificially compressed to a bathing day) can mask large spatial and temporal variability in water quality. If this variability is ignored by taking some mean value and attributing that to all of those exposed in a period at a study location, many bathers may be misclassified and the studies may be biased to a ‘no-effect’ conclusion. A more appropriate approach is to maximise the precision of the epidemiologic investigations by measurement of individual exposure (or water quality) at the place and time of the exposure, as has been done in randomised volunteer studies in the UK and Germany. The precise epidemiologic relationships linking ‘exposure’ with ‘illness’ can then be related to the probability of exposure to particular water quality by a ‘normal bather’ using the known probability distribution of the exposure variable (i.e. faecal indicator concentration) in the regulated bathing waters. We suggest that any research protocol where poor sampling design for water quality assessment is justified because regulatory monitoring is equally imprecise may be fundamentally flawed. The rationale for this assessment is that the epidemiology is the starting point and evidence-base for ‘standards’. If precision is not maximised at this stage in the process it compromises the credibility of the standards design process. The negative effects of the approach advocated in this ‘comment’ are illustrated using published research findings used to derive the figures illustrated in Wymer et al. [2005. Comment on derivation of numerical values for the World Health Organization guidelines for recreational waters. Water Research 39, 2774–2777].

Achieving compliance with the mandatory standards of the 1976 Bathing Water Directive (76/160/EEC) is required at all UK identified bathing waters. In recent years, the Fylde coast has been an area of significant investments in ‘point source’ control, which have not proven, in isolation, to satisfactorily achieve compliance with the mandatory, let alone the guide, levels of water quality in the Directive. The potential impact of riverine sources of pollution was first confirmed after a study in 1997. The completion of sewerage system enhancements offered the potential for the study of faecal indicator delivery from upstream sources comprising both point sources and diffuse agricultural sources. A research project to define these elements commenced in 2001. Initially, a desk study reported here, estimated the principal infrastructure contributions within the Ribble catchment. A second phase of this investigation has involved acquisition of empirical water quality and hydrological data from the catchment during the 2002 bathing season. These data have been used further to calibrate the ‘budgets’ and ‘delivery’ modelling and these data are still being analysed. This paper reports the initial desk study approach to faecal indicator budget estimation using available data from the sewerage infrastructure and catchment sources of faecal indicators.

'Natural' treatment systems such as wetlands and reed beds have been proposed as sustainable means of reducing fluxes of faecal indicator organisms (FIOs) to recreational and shellfish harvesting waters. This is because FIO fluxes to coastal waters from both point (effluent) and diffuse (catchment) sources can cause non-compliance with microbiological standards for bathing and shellfish harvesting waters. The Water Framework Directive requires competent authorities in the member states to manage both point and diffuse sources of FIOs in an integrated manner to achieve compliance with 'good' water quality as defined in a series of daughter Directives. This study was undertaken to investigate the relative sources of FIOs to the popular bathing waters around Clacton, UK. In this predominantly arable (mainly cereal cropping) farming area, the principal land use predictor, explaining 76% of the variance in geometric mean presumptive Escherichia coli concentration at sub-catchment outlets during the bathing season, was the proportion of built-up (i.e. urbanised) land in each sub-catchment. This new finding contrasts with earlier studies in livestock farming regions where the proportion of improved grassland has proven to be the strongest predictor of microbial concentration. Also novel in this investigation, a flood defence wall has been built creating a wetland area which discharges every tidal cycle. The wetland produces over 97% reduction in the flux and concentrations of FIOs to the marine recreational waters. Also, FIO concentrations in water draining through the wetland to the sea were similar to concentrations measured in six UK sewage treatment plant effluents subject to secondary (biological) treatment followed by UV disinfection.

Understanding the process controls on episodic fluxes of faecal indicator organisms (FIOs) is becoming increasingly important for the sustainable management and accurate modelling of water quality in both recreational and shellfish harvesting waters. Both environments exhibit transitory non-compliance with microbiological standards after rainfall episodes despite significant expenditures on control of sewage derived pollutant loadings in recent years. This paper demonstrates the role of wave propagation in the entrainment of FIOs from river channel beds as a contributor to episodes of poor microbial water quality. Previously reported data is reviewed in the light of relationships between wave and mean water travel velocities. High flows and rapid changes in river flow, driven by releases of bacterially pure reservoir water, resulted in elevated FIO concentrations and transient peaks in concentration. The new interpretation of these data suggest three modes of entrainment: (i) immediate wave-front disturbance, (ii) wave propagation lift and post-wave transport at mean flow velocity, and (iii) stochastic erosional mechanisms that maintain elevated bacterial concentrations under steady high flow conditions. This is a significant advance on the previously proposed mechanisms. Understanding these mechanisms provides an aid to managing streams intended for recreational use and emphasises the need to control the timing of high flow generation prior to use of the water body for e.g. canoeing events. In addition the processes highlighted have relevance for the protection of shellfish nurseries, drinking water supply intakes and episodes of poor bathing water quality, and associated health risks.

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.

As the requirements of the Water Framework Directive (WFD) and the US Clean Water Act (USCWA) for the maintenance of microbiological water quality in 'protected areas' highlight, there is a growing recognition that integrated management of point and diffuse sources of microbial pollution is essential. New information on catchment microbial dynamics and, in particular, the sources of faecal indicator bacteria found in bathing and shellfish harvesting waters is a pre-requisite for the design of any 'programme of measures' at the drainage basin scale to secure and maintain compliance with existing and new health-based microbiological standards. This paper reports on a catchment-scale microbial source tracking (MST) study in the Leven Estuary drainage basin, northwest England, an area for which quantitative faecal indicator source apportionment empirical data and land use information were also collected. Since previous MST studies have been based on laboratory trials using 'manufactured' samples or analyses of spot environmental samples without the contextual microbial flux data (under high and low flow conditions) and source information, such background data are needed to evaluate the utility of MST in USCWA total maximum daily load (TMDL) assessments or WFD 'Programmes of Measures'. Thus, the operational utility of MST remains in some doubt. The results of this investigation, using genotyping of Bacteroidetes using polymerase chain reaction (PCR) and male-specific ribonucleic acid coliphage (F + RNA coliphage) using hybridisation, suggest some discrimination is possible between livestock- and human-derived faecal indicator concentrations but, in inter-grade areas, the degree to which the tracer picture reflected the land use pattern and probable faecal indicator loading were less distinct. Interestingly, the MST data was more reliable on high flow samples when much of the faecal indicator flux from catchment systems occurs. Whilst a useful supplementary tool, the MST information did not provide quantitative source apportionment for the study catchment. Thus, it could not replace detailed empirical measurement of microbial flux at key catchment outlets to underpin faecal indicator source apportionment. Therefore, the MST techniques reported herein currently may not meet the standards required to be a useful forensic tool, although continued development of the methods and further catchment scale studies could increase confidence in such methods for future application.

Nitrate production by the surface centimetre of stream sediments was investigated in a wide range of sediment types from five areas in southern Ontario. Nitrification rates were estimated in laboratory incubations and ranged from 0 to 180 mg m −2 d −1 . The highest rates were associated with fine textured and organic samples. Nitrate production rate showed a significant correlation with sediment clay content ( r = 0. 77). Many other sediment properties exhibited weaker significant correlations with nitrate production.