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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., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Environmental water chemistry analysis and microcosm toxicity bioassays (MTB) were performed to assess lethality of herbicides on the mole crab Emerita brasiliensis in a sandy beach affected by a freshwater discharge (Andreoni canal) from rice crops. A 5-yr macrocosm field sampling (MFS) was conducted to evaluate freshwater effects on population abundance. Propanil was only detected at the inner portion of the Andreoni canal (IAC), whereas quinclorac and clomazone were found at the IAC and at the canal mouth (CM). A major propanil metabolite was detected at the CM. Herbicides were undetectable at 13km from the CM. MTB showed an increased susceptibility to propanil with decreasing crab sizes. The MFS showed a drastic decrease in abundance towards the freshwater discharge, concurrently with decreasing salinities. The triad approach that included water analyses, toxicological experiments and long-term field sampling allowed rejecting relationships between herbicide exposure and mole crab lethal effects., (2010 Elsevier Ltd. All rights reserved.)

The increasing demands on recreational waters have made microbial contamination a matter of public and scientific concern. This study aimed to search for Salmonella spp. in waters classified according EU Directive 2006/7/EC, in order to assess associations between its prevalence and the concentration of the non-pathogenic new faecal indicators: Escherichia coli and intestinal enterococci. Although a statistically significant association was observed Salmonella was detected on beaches classified as "Good" (9.3%) and "Excellent" (14.4%) which compromises the idea that faecal indicators can be predictors of pathogens. Attending the high prevalence of Salmonella found (23.1%) it seemed important to improve the efficiency of the conventional analytical method (ISO 6340:1995), comparing its draft with SML-VIDAS Salmonella and two new chromogenic media: AES Salmonella Agar Plate (ASAP) and Simple Method Salmonella (SMS). ASAP showed the higher efficiency and can be recommended for a faster detection and presumptive identification of salmonellae in bathing waters.

The U.S. Environmental Protection Agency (EPA) has committed to issuing in 2012 new or revised criteria designed to protect the health of those who use surface waters for recreation. For this purpose, the U.S. EPA has been conducting epidemiologic studies to establish relationships between microbial measures of water quality and adverse health outcomes among swimmers. New methods for testing water quality that would provide same-day results will likely be elements of the new criteria. Although the epidemiologic studies upon which the criteria will be based were conducted at Great Lakes and marine beaches, the new water quality criteria may be extended to inland waters (IWs). Similarities and important differences between coastal waters (CWs) and IWs that should be considered when developing criteria for IWs were the focus of an expert workshop. Here, we summarize the state of knowledge and research needed to base IWs microbial criteria on sound science. Two key differences between CWs and IWs are the sources of indicator bacteria, which may modify the relationship between indicator microbes and health risk, and the relationship between indicators and pathogens, which also may vary within IWs. Monitoring using rapid molecular methods will require the standardization and simplification of analytical methods, as well as greater clarity about their interpretation. Research needs for the short term and longer term are described.

A composite index, based on function analysis and including thirteen sub-indices, was developed to assess the overall quality of urban and urbanized beaches in the Mediterranean area. The aggregation of components and sub-indices was based on two questionnaires completed by beach users and experts. Applying the new Beach Quality Index (BQI) demonstrated that the quality of beaches could be improved. In general, the strongest aspects of the beaches assessed were those related to short-term user demand, and the weakest were those related to the consequences of human pressure on the area, in particular, erosion problems. The composite index is intended to be used together with Environmental Management Beach Systems (EMBs) as a hierarchical management scorecard and in monitoring programs. This new tool could also make planning more proactive by synthesizing the state of the most important beach processes.

The risk of gastrointestinal illness to swimmers from fresh sewage and non-sewage fecal sources at recreational beaches was predicted using quantitative microbial risk assessment (QMRA). The QMRA estimated the probability of illness for accidental ingestion of recreational water with a specific concentration of fecal indicator bacteria, here the geometric mean enterococci limit of 35 cfu 100 mL(-1), from either a mixture of sources or an individual source. Using seagulls as an example non-sewage fecal source, the predicted median probability of illness was less than the illness benchmark of 0.01. When the fecal source was changed to poorly treated sewage, a relativity small difference between the median probability of illness and the illness benchmark was predicted. For waters impacted by a mixture of seagull and sewage waste, the dominant source of fecal indicator was not always the predicted dominant source of risk.

Beaches throughout the Great Lakes are monitored for fecal indicator bacteria (typically Escherichia coli) in order to protect the public from potential sewage contamination. Currently, there is no universal standard for sample collection and analysis or results interpretation. Monitoring policies are developed by individual beach management jurisdictions, and applications are highly variable across and within lakes, states, and provinces. Extensive research has demonstrated that sampling decisions for time, depth, number of replicates, frequency of sampling, and laboratory analysis all influence the results outcome, as well as calculations of the mean and interpretation of the results in policy decisions. Additional shortcomings to current monitoring approaches include appropriateness and reliability of currently used indicator bacteria and the overall goal of these monitoring programs. Current research is attempting to circumvent these complex issues by developing new tools and methods for beach monitoring. In this review, we highlight the variety of sampling routines used across the Great Lakes and the extensive body of research that challenges comparisons among beaches. We also assess the future of Great Lakes monitoring and the advantages and disadvantages of establishing standards that are evenly applied across all beaches.

Swimming in ocean water, including ocean water at beaches not impacted by known point sources of pollution, is an increasing health concern. This study was an initial evaluation of the presence of indicator microbes and pathogens and the association among the indicator microbes, pathogens, and environmental conditions at a subtropical, recreational marine beach in south Florida impacted by non-point sources of pollution. Twelve water and eight sand samples were collected during four sampling events at high or low tide under elevated or reduced solar insolation conditions. The analyses performed included analyses of fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli, enterococci, and Clostridium perfringens), human-associated microbial source tracking (MST) markers (human polyomaviruses [HPyVs] and Enterococcus faecium esp gene), and pathogens (Vibrio vulnificus, Staphylococcus aureus, enterovirus, norovirus, hepatitis A virus, Cryptosporidium spp., and Giardia spp.). The enterococcus concentrations in water and sand determined by quantitative PCR were greater than the concentrations determined by membrane filtration measurement. The FIB concentrations in water were below the recreational water quality standards for three of the four sampling events, when pathogens and MST markers were also generally undetectable. The FIB levels exceeded regulatory guidelines during one event, and this was accompanied by detection of HPyVs and pathogens, including detection of the autochthonous bacterium V. vulnificus in sand and water, detection of the allochthonous protozoans Giardia spp. in water, and detection of Cryptosporidium spp. in sand samples. The elevated microbial levels were detected at high tide and under low-solar-insolation conditions. Additional sampling should be conducted to further explore the relationships between tidal and solar insolation conditions and between indicator microbes and pathogens in subtropical recreational marine waters impacted by non-point source pollution.

The European Community Bathing Water Directive (European Parliament, 2006) set compliance standards for bathing waters across Europe, with minimum standards for microbiological indicators to be attained at all locations by 2015. The Directive allows up to 15% of samples affected by short-term pollution episodes to be disregarded from the figures used to classify bathing waters, provided certain management criteria have been met, including informing the public of short-term water pollution episodes. Therefore, a scientifically justifiable discounting limit is required which could be used as a management tool to determine the samples that should be removed. This paper investigates different methods of obtaining discounting limits, focusing in particular on extreme value methodology applied to data from Scottish bathing waters. Return level based limits derived from threshold models applied at a site-specific level improved the percentage of sites which met at least the minimum required standard. This approach provides a method of obtaining limits which identify the samples that should be removed from compliance calculations, although care has to be taken in terms of the quantity of data which is removed., ((c) 2009 Elsevier Ltd. All rights reserved.)

The study used existing indicator bacterial data and a number of physicochemical parameters that can be measured instantaneously to determine if a decision tree approach, especially classification and regression tree, could be used to predict bacterial concentrations in timely manner for beach closure management. Each indicator bacteria showed different tree structures and each had its own significant variables; Dissolved oxygen played an important role for both total coliform and fecal coliform and turbidity was the most important factor to predict concentrations of enterococci for decision tree approaches. Root mean squared error stayed between 5 and 6.5% of the average values of observations; RMSEs from each simulation, 0.25 for total coliform, 0.31 for fecal coliform, and 0.29 for enterococci. Estimations from tree structures would be regarded as a good representation of the actual data. In addition to results of the objective function, RMSE, 77.5% of actual value fell into the 95% of confidence interval of estimations for total coliform concentrations, 60% for fecal coliform concentrations, and 62.5% for enterococci concentrations. The approach showed reliable estimations for the majority of the data processed, although the method did not portray low concentrations of bacteria as well.

The environmental authority of Taiwan has announced that ocean quality standard A, with E. coli less than 1,000 CFU/100 mL is safe for swimming. Ta-An Beach in central Taiwan was found to have exceeded 1,000 CFU/100 mL, which is 51% of the total monitoring records. Sewage, piggery and duck wastewater are discharged directly into this area. The traditional pollution source trace methods did not clearly identify the pollution source. This study used PCR-DGGE technology to establish micro-organisms fingerprints from water samples using comparative analysis with microbiological composition, and then determined the possible sources of biological contamination. The E. coli colonies at all samples were processed using linear regression analysis and compared with each other. The R(2) is 0.4102-0.7387 for the livestock farm and beach. This shows a positively relation. The piggery impact is more obvious. The beach microbial communities exhibited high similarity with piggery wastewater from the upstream region. We confirmed that the major pollution source for Ta-An Beach comes from piggery wastewater. The proposed method has high stability and reliability. It can be used as the basis for rapid identification of pollution sources at other beach water sites in the future.

Cladophora in the Great Lakes grows rapidly during the warm summer months, detaches, and becomes free-floating mats as a result of environmental conditions, eventually becoming stranded on recreational beaches. Cladophora provides protection and nutrients, which allow enteric bacteria such as Escherichia coli, enterococci, Shigella, Campylobacter, and Salmonella to persist and potentially regrow in the presence of the algae. As a result of wind and wave action, these microorganisms can detach and be released to surrounding waters and can influence water quality. Enteric bacterial pathogens have been detected in Cladophora mats; E. coli and enterococci may populate to become part of the naturalized microbiota in Cladophora; the high densities of these bacteria may affect water quality, resulting in unnecessary beach closures. The continued use of traditional fecal indicators at beaches with Cladophora presence is inadequate at accurately predicting the presence of fecal contamination. This paper offers a substantial review of available literature to improve the knowledge of Cladophora impacts on water quality, recreational water monitoring, fecal indicator bacteria and microorganisms, and public health and policy.

The calculation of percentiles proposed in the Directive 2006/7/EC (parametric approach) to evaluate bathing water quality uses two parameters: mean (micro) and standard deviation (sigma). These two parameters are good descriptors of data populations only when data are log normally distributed. Several previous studies have shown that a log transformation is sufficient to achieve normality, while other studies suggest that log normality in bathing water quality datasets is seldom attained. In our study, log normality was achieved in 59.6% of the cases. In order to try to obtain a transformation parameter for Box-Cox (lambda) that provides the best fit and perhaps normality in bathing water datasets, the maximum likelihood estimation (MLE) method was applied to 40.4% of the remaining (non log normal) datasets. Results show that there is no transformation parameter that ensures normality for all datasets. In fact, normality is only reached in 10.3% of these datasets but, in these cases, the parametric approach seems to be a good one to evaluate bathing water quality. In cases where normality was not fulfilled even by application of the MLE method, a non-parametric approach to calculate percentiles is considered the most appropriate one. When percentile values obtained through the parametric and non-parametric Hazen approaches are compared, it is shown that the percentage of bathing waters changing their classification is low (12.3%). In these cases, the Hazen approach provides the worst classification in a vast majority of cases (90.6%), being this change important in some cases, in which classification is downgraded from having "Excellent" to "Sufficient" quality. Therefore, the Hazen approach is more appropriate for calculating percentiles, since it provides better estimators of percentile values. Furthermore, this method involves a more conservative approach for the classification of bathing water quality, providing an additional security for bathers' health. The fact that normality is not fulfilled and that classification of bathing waters could change must be considered by policymakers in order to adopt an alternative method for evaluating bathing waters quality.

Bathing water quality is an important public health issue, mainly because of fecal contamination. In 2006, the European Commission (EC) adopted a new directive with respect to recreational bathing waters that calls for stricter standards and reduces the number of laboratory tests done in routine beach monitoring from nineteen to two bacterial indicators, namely, Escherichia coli and intestinal enterococci, replacing policies of the EC Bathing Water Directive that have existed since 1976. Our practice in Portugal is in line with this international development, and this study demonstrates the equivalency of the new bacteriological parameters with the old. The water quality of 25 coastal beaches was surveyed using both new and old microbiological indicators of fecal contamination. Statistical analysis demonstrated equivalency of the results obtained for fecal coliforms with Escherichia coli and for fecal streptococci with intestinal enterococci.

The purpose of this study was to evaluate the efficiency of the recent (2006) European Union Directive concerning the management of bathing water quality to exclude the presence of pathogens from complying waters. Coastal water samples were classified according to the Directive. 2.5% of 'excellent' water contained Salmonella and 39.2% Candida albicans 11.8% of samples in category 'good' were Salmonella positive and 35.2% were C.albicans positive. When the USEPA criterion for marine waters was applied to the same dataset, fewer samples complied, however 6.0% of the complying samples contained Salmonella. The results suggest that the bacterial indicator threshold levels for marine recreational water quality of the 2006/7/EC European Union Directive do not fully exclude contact of bathers with dangerous pathogens. Enterococci, if used as the sole index, appear to form a more reliable proxy of the risk of contact with Salmonella.

The European Union (EU) Bathing Water Directive (2006/7/EC) sets out standards for designated bathing waters which should be complied with by all Member States. Turkey, being a candidate country to the EU, requires heavy-cost investments in achieving approximation with the EU Environmental Acquis. This paper provides a description of the technical measures and investment and operational cost assessment related to the implementation of the Bathing Water Directive in Turkey. Bathing waters are defined as "all running or still freshwaters or parts thereof and seawater, in which bathing is explicitly authorized by the competent authorities, or bathing is not prohibited and is traditionally practiced by a large number of bathers". Since there is no complete registration of bathing waters in Turkey, this study has targeted all coastal agglomerations and designated these as in proximity to "highly-touristic" and "other" agglomerations including the agglomerations in the proximity of six lakes that are popularly used as bathing waters. For each of these agglomerations an assessment of the existing infrastructure has been made. In defining the infrastructural need, two scenarios have been developed. According to Scenario 1, only highly-touristic and touristic places are to receive investment. The suggested further treatment was "disinfection+sea outfall" and "sea-outfall", for highly-touristic and touristic agglomerations, respectively. In Scenario 2, other coastal agglomerations and all freshwater lakes were also included and disinfection has been proposed for these settlements. It appears that the total investment is at around 12.6 million Euros for Scenario 1 and increases to 21.8 million Euros for Scenario 2; whereas the annual operational and maintenance costs are about 0.5 and 0.8 million Euros for Scenarios 1 and 2, respectively.

This study assessed coastal erosion vulnerability along a 90-km sector, which included both erosional and accretionary beaches, and different levels of human occupation. Two aerial photogrammetric flights were used to reconstruct coastal evolution between 1977 and 1999. During this period, extensive accretion was recorded updrift of human structures at harbors and ports, e.g., Scoglitti (105.6 m), Donnalucata (52.8 m), and Pozzallo (94.6 m). Conversely, erosion was recorded in downdrift areas, with maximum values at Modica Stream mouth (63.8 m) and Point Castellazzo (35.2 m). Assessments were subsequently divided into four categories ranging from "high erosion" to "accretion." Several sources were examined to assess human activities and land use. The latter was mapped and divided into four categories, ranging from "very high" to "no capital" land use. Subsequently, coastal erosion vulnerability was assessed by combining land use categories with recorded coastline behavior. Results showed "very high" to "high" vulnerability along 5.8% and 16.6%, respectively, of the littoral, while 20.9% and 56.7%, respectively, was found to exhibit "medium" and "low/very low" vulnerability. A very good agreement between predicted coastal vulnerability and coastal trend had been observed over recent years. Furthermore, several human structures and activities are located within the "imminent collapse zone (ICZ)" which reached maximum values of 17.5 m at Modica Stream and 13.5 m at Point Braccetto.

Pseudomonas aeruginosa (P. aeruginosa) is a relevant pathogen to bathers and, therefore, water from natural swimming pools is analyzed for its presence. P. aeruginosa can be detected regularly in surface waters. Currently the methods described in DIN EN 12780 are recommended for the quantitative analysis of water from natural swimming pools, although this standard was developed for bottled water. The present study examines whether the recommendation is satisfactory. In 93 water samples from five natural swimming pools (Naturschwimmteiche), 3226 presumptive P. aeruginosa colonies were detected. Of the 3226 colonies, 101 were directly confirmed due to their formation of pyocyanin. From the remaining 3125 colonies, 349 representative samples were isolated and examined further. Using the criteria of DIN EN 12780 fluorescense and ammonia formation from acetamide, another 45 colonies were considered to be P. aeruginosa. 71% (32) of these 45 non-pyocyanin-forming strains could not be confirmed by the APINE system. None of the 32 strains grew at 42 degrees C, which is a characteristic feature of P. aeruginosa as mentioned in a note of DIN EN 12780. In 20 of the original samples, P. aeruginosa numbers exceeded the recommended limit value of 10/100 ml. Eleven cases (55 %) were caused by P. aeruginosa, which were not confirmed taxonomically. Due to insufficient selectivity, the method according to DIN EN 12780 is not applicable for the testing of surface waters and water from natural swimming pools. The high number of false positive results for P. aeruginosa questions the standard even further. It is suggested that for surface water samples growth of P. aeruginosa at 42 degrees C has to be checked as an additional confirmation characteristics of P. aeruginosa until a reliable standard is published.

This paper exploited the potential of the wavelet analysis in resolving beach bacteria concentration and candidate explanatory variables across multiple time scales with temporal information preserved. The wavelet transform of E. coli concentration and its explanatory variables observed at Huntington Beach, Ohio in 2006 exhibited well-defined patterns of different time scales, phases, and durations, which cannot be clearly shown in conventional time-domain analyses. If linear regression modeling is to be used for the ease of implementation and interpretation,the wavelet-transformed regression model reveals that low model residual can be realized through matching major patterns and their phase angles between E. coli concentration and its explanatory variables. The property of pattern matching for linear regression models can be adopted as a criterion for choosing useful predictors, while phase matching further explains why intuitively good variables such as wave height and onshore wind speed were excluded from the optimal models by model selection processes in Frick et al. (Environ. Sci. Technol. 2008, 42,4818-4824). The phase angles defined by the wavelet analysis in the time-frequency domain can help identify the physical processes and interactions occurring between bacteria concentration and its explanatory variables. It was deduced, for this particular case, that wind events resulted in elevated E. coli concentration, wave height, and turbidity at the beach with a periodicity of 7-8 days. Wind events also brought about increased beach bacteria concentrations through large-scale current circulations in the lake with a period of 21 days. The time length for linear regression models with statistical robustness can also be deduced from the periods of the major patterns in bacteria concentration and explanatory variables, which explains and supplements the modeling efforts performed in (1).

The overall goal of the study reported herein was to use techniques in the field of risk assessment (specifically a state-space population dynamic model of disease transmission within recreational waters) to explore the relative significance of (1) active shedding of microorganisms from bathers themselves, and (2) the type and concentration of etiological agent on the observed heterogeneity of the incidence of illness in epidemiological studies that have been used to develop ambient water quality criteria. The etiological agent and corresponding dose ingested during recreational contact was found to significantly impact the observed incidence of illness in an epidemiological study conducted in recreational water. In addition, the observed incidence of illness was found not to necessarily reflect background concentrations of indicator organisms, but rather microorganisms shed during recreational contact. Future revisions to ambient water quality criteria should address the etiological agent, dose, and the significance of microbial shedding relative to background concentrations of pathogens and indicator organisms in addition to the incidence of illness and concentration of indicator organisms. Without a quantitative assessment of these additional variables, study findings may potentially be site specific and not representative of the health risks associated with specific indicator concentrations in all recreational waters.

"Bathing ponds" are artificial outdoor water pools without disinfection. Whereas in conventional pools, chlorine promptly kills pathogens shed by bathers, such quick inactivation is missing in bathing ponds. We have explored the retention of indicator bacteria and viruses by a vertically operated, reed grown soil filter. After continuously running the filter with wastewater-spiked surface water, we found that the filter retains more than 99 % of the indicator organisms. It has been reported in the literature that the "spontaneous" inactivation of pathogens in water might be very variable depending on sunlight irradiation, water turbidity, etc. On the contrary, the performance of a filter like the one reported here allows filtering the water so as to reliably eliminate 90 % of the spiked microorganisms from the pool water within 24 hours.

Synthetic polymers, commonly known as plastics, have been entering the marine environment in quantities paralleling their level of production over the last half century. However, in the last two decades of the 20th Century, the deposition rate accelerated past the rate of production, and plastics are now one of the most common and persistent pollutants in ocean waters and beaches worldwide. Thirty years ago the prevailing attitude of the plastic industry was that "plastic litter is a very small proportion of all litter and causes no harm to the environment except as an eyesore" [Derraik, J.G.B., 2002. The pollution of the marine environment by plastic debris: a review. Mar. Pollut. Bull. 44(9), 842-852]. Between 1960 and 2000, the world production of plastic resins increased 25-fold, while recovery of the material remained below 5%. Between 1970 and 2003, plastics became the fastest growing segment of the US municipal waste stream, increasing nine-fold, and marine litter is now 60-80% plastic, reaching 90-95% in some areas. While undoubtedly still an eyesore, plastic debris today is having significant harmful effects on marine biota. Albatross, fulmars, shearwaters and petrels mistake floating plastics for food, and many individuals of these species are affected; in fact, 44% of all seabird species are known to ingest plastic. Sea turtles ingest plastic bags, fishing line and other plastics, as do 26 species of cetaceans. In all, 267 species of marine organisms worldwide are known to have been affected by plastic debris, a number that will increase as smaller organisms are assessed. The number of fish, birds, and mammals that succumb each year to derelict fishing nets and lines in which they become entangled cannot be reliably known; but estimates are in the millions. We divide marine plastic debris into two categories: macro, >5 mm and micro, <5 mm. While macro-debris may sometimes be traced to its origin by object identification or markings, micro-debris, consisting of particles of two main varieties, (1) fragments broken from larger objects, and (2) resin pellets and powders, the basic thermoplastic industry feedstocks, are difficult to trace. Ingestion of plastic micro-debris by filter feeders at the base of the food web is known to occur, but has not been quantified. Ingestion of degraded plastic pellets and fragments raises toxicity concerns, since plastics are known to adsorb hydrophobic pollutants. The potential bioavailability of compounds added to plastics at the time of manufacture, as well as those adsorbed from the environment are complex issues that merit more widespread investigation. The physiological effects of any bioavailable compounds desorbed from plastics by marine biota are being directly investigated, since it was found 20 years ago that the mass of ingested plastic in Great Shearwaters was positively correlated with PCBs in their fat and eggs. Colonization of plastic marine debris by sessile organisms provides a vector for transport of alien species in the ocean environment and may threaten marine biodiversity. There is also potential danger to marine ecosystems from the accumulation of plastic debris on the sea floor. The accumulation of such debris can inhibit gas exchange between the overlying waters and the pore waters of the sediments, and disrupt or smother inhabitants of the benthos. The extent of this problem and its effects have recently begun to be investigated. A little more than half of all thermoplastics will sink in seawater.

A total of 357 water samples were collected from a public beach in northern Taiwan during beach season, and the densities of enterococci were analyzed by Enterolert methods. The mean enterococci level was 356 MPN/100 ml and ranged from <10 to 2,005 MPN/100 ml, which was classified as high contamination level according to the WHO water quality guideline (95 percentile >1,000 MPN/100 ml). Most of the deteriorated water quality conditions occurred during rainfall. By excluding data from the rain days, the overall beach water quality would be considered in the moderate contamination level (95 percentile 200-1,000 MPN/100 ml). Among the selected microbiological parameters tested, the densities of total coliforms and enterococci exhibited the highest correlation (r = 0.449, p = 0.009), followed by the concentrations of total coliforms and fecal coliforms (r = 0.403, p = 0.02). Nonetheless, no significant correlation was found between enterococci and fecal coliform levels (r = 0.197, p = 0.271).

The present-day sanitary state of most sea beaches within the precincts of Vladivostok is mainly determined by the fact that pollutants along with household and industrial sewerage flows are carried away into the beaches without proper treatment. A multitude of the pathogenic and opportunistic flora with fecal sewerage flows enters the coastal zone. In summer holiday months (July and August), beach-front areas of the city are polluted with organic substances, i.e. they are characterized as polysaprobic, which creates conditions for the multiplication of pathogenic microorganisms. In terms of sanitary and microbiological indices, the surface waters in the city's recreational zones are characterized by persistent fecal pollution that greatly exceeds the sanitary standards, abundant enterobacteria, including epidemiologically potentially dangerous species.

A simple model predicting bathing water concentrations of Escherichia coli from livestock in the Irvine catchment in SW Scotland has been adapted for intestinal enterococci (IE). This has been used to predict risk of bather illness by extrapolation of published data on bather IE exposure vs incidence of gastro-enteritis. Simulated reduction in the risk of illness by reduced faecal loading was multiplied by a willingness to pay for risk reduction to estimate the annual benefits of mitigation. Health benefits of reducing loading by 75% at Irvine Beach were estimated by a willingness to pay method to be about pound 276k pa. Estimated annualised costs of diffuse pollution mitigation measures across the catchment were higher (> pound 1m), and it is very unlikely that 75% mitigation is achievable with current stocking rates. Further work should explore the influence of uncertainty of model parameters, and use emerging epidemiological information on specific zoonotic pathogens such as E. coli O157 and Cryptosporidium. Other components of the value of clean water should also be included to obtain a complete estimate of the cost:benefit of mitigation.

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.

Beach advisories are issued to the public in California when the concentration of fecal indicator bacteria (FIB), including total coliform, fecal coliform (or Escherichia coli), and Enterococcus, exceed their recreational water health standards, or when the amount of a rainfall event is above the pre-determined threshold. However, it is not fully understood about how and to what degree stormwater runoff or baseflow exerts impacts on beach water quality. Furthermore, current laboratory methods used to determine the FIB levels take 18-96 h, which is too slow to keep pace with changes in FIB levels in water. Thus, a beach may not be posted when it is contaminated, and may be posted under advisory when bacterial levels have already decreased to within water quality standards. The study was designed to address the above critical issues. There were large temporal and spatial variations in FIB concentrations along two popular State Beaches in San Diego, CA, USA. The rainstorm-induced runoff from the watersheds exerts significant impacts on the marine recreational water quality of the beaches adjacent to lagoons during the first 24-48 h after a rain event. The large volume of stormwater runoff discharging to beaches caused high FIB concentrations in beach water not only at the lagoon outlet channel and the mixing zone, but also at the locations 90 m away from the channel northward or southward along the shoreline. The geomorphology of beach shoreline, distance from the outlet channel, wind strength, wind direction, tide height, wave height, rainfall, time lapse after a rainstorm, or channel flow rate played a role in affecting the distribution of FIB concentrations in beach water. Despite the great temporal and spatial variability of FIB concentrations along a shoreline, the artificial neural network-based models developed in this study are capable of successfully predicting FIB concentrations at different beaches, different locations, and different times under baseflow or rainstorm conditions. The models are based on readily measurable variables including temperature, conductivity, pH, turbidity, channel water flow, rainfall, and/or time lapse after a rainstorm. The established models will help fill the current gap between beach posting and actual water quality and make more meaningful and effective decisions on beach closures and advisories.

In early 1999, primary treatment and discharge of sewage from Tijuana, Mexico (approximately 95 million liters per day) began through South Bay Ocean Outfall (SBOO) into the ocean 4.3 km offshore. In this study, statistical comparisons were made of the bacterial water quality (total and fecal coliforms and enterococci densities) of the ocean, both before and after discharge of sewage to the SBOO began, so that the effect of this ocean discharge on nearshore ocean water quality could be quantitatively assessed. The frequency of exceedence of bacterial indicator thresholds was statistically analyzed for 11 shore (surfzone) stations throughout US and Mexico using the Fisher's exact test, for the years before (1995-1998) as compared to after the SBOO discharge began (1999-2003). Only four of the 11 shoreline stations (S2, S3, S11, and S12) showed significant improvement (decreased frequency of exceedence of bacterial indicator thresholds) after SBOO discharge began.

Internet-based methods of disease investigation have proven useful for drinking water and foodborne illness but have not been applied to recreational water illness (RWI) in marine bathers. We analyzed responses to a web-based survey posted by Surfrider Foundation over the period 1996-2005. Subjects (n=1895) were recruited by self-selection via website visitation. Complaints were screened to meet inclusion criteria (n=1190). Demographic characteristics of respondents were assessed as well as the types and severity of their symptoms. Geographic information systems (GIS) were used to examine spatial patterns in survey data. Illness complaints were commonly received in summer from heavily used California beaches. A strong correlation was observed between water quality impairment and the number of illness complaints in coastal counties (r=0.96, p<0.01). Respondents most commonly complained of gastrointestinal symptoms, infections of the sinuses and other upper respiratory ailments. Certain severe symptoms, such as high fevers, severe vomiting and/or diarrhea, seizures, swollen glands, and infections that did not heal properly were also reported. Approximately one-third of respondents sought the care of a physician for their symptoms; however, less than 1% reported being hospitalized. Our findings concerning the nature of the described symptoms as well as the observed seasonal and spatial patterns in the data are consistent with previously published findings of RWI in ocean bathers exposed to sewage and urban runoff. This method of rapid RWI data collection over the web could easily be adopted by health agencies for coordinated disease surveillance.

Two public beaches (Anderson and Hilton) in Newport News, Virginia, were frequently closed to swimming in 2004 due to high Enterococcus spp. counts that exceeded the regulatory standard. The microbial source tracking (MST) methods of antibiotic resistance analysis (ARA) and fluorometry (to detect optical brighteners) were used in the summer of 2004 to determine the origins of fecal pollution at the two beaches. Both MST methods detected substantial human-origin pollution at the two beaches, in locations producing consistently high levels of Enterococcus spp. Investigations by municipal officials led to the fluorometric detection and subsequent repair of sewage infrastructure problems at both beaches. The success of the mitigation efforts was confirmed during the summer of 2005 using ARA and fluorometry, with the results cross-validated by pulsed-field gel electrophoresis (PFGE).

The recent implementation of the Revised Bathing Water Directive in the European Union has highlighted the need for development of effective methods to differentiate between sources of faecal contamination. It had previously been shown that amplification of 16S rRNA genes of host-specific Bacteriodales species using the HF183F and CF128F primers could be used as markers for human and bovine faecal contamination in the United States. This paper determined the sensitivity and specificity of these markers in four Atlantic Rim countries (France, Ireland, Portugal and the United Kingdom) to evaluate their usefulness in determining the origin of faecal contamination. It was shown that the HF183F marker displayed high sensitivity (80-100%) and specificity (91-100%), and is reliable as an indication of human faecal contamination. The CF128F marker displayed 100% sensitivity in all four countries. However, strong regional variations in specificity (41-96%) were observed, highlighting the need for local validation before this marker is employed in source tracking of faecal contamination.

The effect of a stormwater conveyance system on indicator bacteria levels at a Florida beach was assessed using microbial source tracking methods, and by investigating indicator bacteria population structure in water and sediments. During a rain event, regulatory standards for both fecal coliforms and Enterococcus spp. were exceeded, contrasting with significantly lower levels under dry conditions. Indicator bacteria levels were high in sediments under all conditions. The involvement of human sewage in the contamination was investigated using polymerase chain reaction (PCR) assays for the esp gene of Enterococcus faecium and for the conserved T antigen of human polyomaviruses, all of which were negative. BOX-PCR subtyping of Escherichia coli and Enterococcus showed higher population diversity during the rain event; and higher population similarity during dry conditions, suggesting that without fresh inputs, only a subset of the population survives the selective pressure of the secondary habitat. These data indicate that high indicator bacteria levels were attributable to a stormwater system that acted as a reservoir and conduit, flushing high levels of indicator bacteria to the beach during a rain event. Such environmental reservoirs of indicator bacteria further complicate the already questionable relationship between indicator organisms and human pathogens, and call for a better understanding of the ecology, fate and persistence of indicator bacteria.

Sediments of five Ligurian beaches in compliance with European Union bathing water regulations were studied based on the characteristics of the fungal assemblage during the tourism season. Among the 179 taxa of filamentous fungi isolated, 120 were opportunistic pathogens, such as Acremonium sp., and the genus Penicillium was also present as the pathogenic species P. citrinum. Furthermore, 5% of the total filamentous fungi belonged to the dermatophyte genus Microsporum, whose species can cause mycoses. Beach sediments showed elevated densities of opportunistic pathogens, of pathogenic filamentous fungi, and of yeasts during the tourism season. Although monitoring of beach sediments for microbiological contamination is not mandatory, and disease transmission from sediments has not yet been demonstrated, our study suggests that beach sediments may act as a reservoir of potential pathogens, including fungi. In addition, the mycoflora displayed high sensitivity to critical environmental situations in the beaches studied. Therefore, the fungal community can be a useful tool for assessing the quality of sandy beaches in terms of sanitary and environmental quality.

The European Water Framework Directive requires the integrated management of point and diffuse pollution to achieve 'good' water quality in 'protected areas'. These include bathing waters, which are regulated using faecal indicator organisms as compliance parameters. Thus, for the first time, European regulators are faced with the control of faecal indicator fluxes from agricultural sources where these impact on bathing water compliance locations. Concurrently, reforms to the European Union (EU) Common Agricultural Policy offer scope for supporting on-farm measures producing environmental benefits through the new 'single farm payments' and the concept of 'cross-compliance'. This paper reports the first UK study involving remedial measures, principally stream bank fencing, designed to reduce faecal indicator fluxes at the catchment scale. Considerable reduction in faecal indicator flux was observed, but this was insufficient to ensure bathing water compliance with either Directive 76/160/EEC standards or new health-evidence-based criteria proposed by WHO and the European Commission.

A revised version of the Bathing Water Directive 76/160/EWG has been elaborated to include scientific progress in risk assessment of bathing-related illness. The new Bathing Water Directive 2006/7/EC came into force on March 24, 2006, and will have to be implemented in the federal states within two years. The new bathing water directive contains several positive innovations which will improve a protection of the bathers namely i) health related indicators, ii) uniform detection methods, iii) requirements for active bathing water management, and iv) stricter standards for coastal waters. In Germany, the 16 federal states of the Federal Republic of Germany - the Länder - are responsible for monitoring bathing waters and for implementing the new bathing water directive into national law. A common master directive is being written by a joint working-group to ensure comparable implementation in all parts of Germany. An immediate application of the new directive is not possible since the parameter "intestinal enterococci" is currently not routinely monitored. It was decided to start monitoring according to the new directive in Germany in 2008. This will allow the first classification of bathing waters according to the new directive in 2011.

The solid waste accumulation patterns on Tamandaré beach, Pernambuco State (Brazil), was assessed from February 2001 to July 2002. This beach is easily accessible, frequently used, and there is a public cleaning service. The beach is under the influence of three small coastal drainage basins. The study visually divided the beach into 15 segments according to the level of solid waste contamination into absent (A), trace (B), unacceptable (C) and objectionable (D). The lowest levels of contamination were found at the middle part of the study area, the most vulnerable in respect to coastal erosion presenting numerous interventions on the beach, absence of native vegetation and lesser width. The highest levels of contamination were at the northern and southern ends of the area, where there are no developments, the beach morphology favours deposition of sediments, there is native vegetation and the beach is wider. The D level did not occur within the area.

While the US Environmental Protection Agency's (EPA) Beaches Environmental Assessment and Coastal Health (BEACH) Act requires coastal and Great Lakes' states to implement plans for monitoring bacterial contamination of recreational beach water, exactly how this monitoring should occur has not been regulated. This study examined differences in concentration of Escherichia coli in water collected from different depths and from different horizontal locations across the beach. E. coli concentrations were significantly different (p<0.05), when water from different depths was compared. Sampling water at depths of 30, 60, and 120 cm resulted in significantly lower E. coli concentrations as depth increased. Had the State of Wisconsin chosen to collect beach water monitoring samples at a shallower or deeper depth, numbers of beach closures and the potential risk to public health would have changed substantially. These data imply that a revised and standardized protocol for monitoring beach water should be adopted by all states of a monitoring region to better compare microbial contamination of beaches and protect public health.

We studied the shoreward and seasonal distribution of E. coil and enterococci in sand (at the water table) at two southern Lake Michigan beaches-Dunbar and West Beach (in Indiana). Deep, backshore sand (approximately 20 m inland) was regularly sampled for 15 months during 2002-2003. E. coli counts were not significantly different in samples taken at 5-m intervals from 0-40 m inland (P = 0.25). Neither E. coli nor enterococci mean counts showed any correlation or differences between the two beaches studied. In laboratory experiments, E. coli readily grew in sand supplemented with lake plankton, suggesting that in situ E. coil growth may occur when temperature and natural organic sources are adequate. Of the 114 sand enterococci isolates tested, positive species identification was obtained for only 52 (46%), with E. faecium representing the most dominant species (92%). Genetic characterization by ribotyping revealed no distinct genotypic pattern (s) for E. coli, suggesting that the sand population was rather a mixture of numerous strains (genotypes). These findings indicate that E. coli and enterococci can occur and persist for extended periods in backshore sand at the groundwater table. Although this study was limited to two beaches of southern Lake Michigan, similar findings can be expected at other temperate freshwater beaches. The long-term persistence of these bacteria, perhaps independent of pollution events, complicates their use as indicator organisms. Further, backshore sand at the water table may act as a reservoir for these bacteria and potentially for human pathogens.

Fecal indicator bacteria (FIB) were measured approximately 5 days a week in ankle-depth water at 19 surfzone stations along Huntington Beach and Newport Beach, California, from 1998 to the end of 2003. These sampling periods span the time before and after treated sewage effluent, discharged into the coastal ocean from the local outfall, was disinfected. Bacterial samples were also taken in the vicinity of the outfall during the pre- and post-disinfection periods. Our analysis of the results from both data sets suggest that land-based sources, rather than the local outfall, were the source of the FIB responsible for the frequent closures and postings of local beaches in the summers of 2001 and 2002. Because the annual cycle is the dominant frequency in the fecal and total coliform data sets at most sampling stations, we infer that sources associated with local runoff were responsible for the majority of coliform contamination along wide stretches of the beach. The dominant fortnightly cycle in enterococci at many surfzone sampling stations suggests that the source for these relatively frequent bacteria contamination events in summer is related to the wetting and draining of the land due to the large tidal excursions found during spring tides. Along the most frequently closed section of the beach at stations 3N-15N, the fortnightly cycle is dominant in all FIBs. The strikingly different spatial and spectral patterns found in coliform and in enterococci suggest the presence of different sources, at least for large sections of beach. The presence of a relatively large enterococci fortnightly cycle along the beaches near Newport Harbor indicates that contamination sources similar to those found off Huntington Beach are present, though not at high enough levels to close the Newport beaches.

Fecal indicator bacteria concentrations measured in the surf zone off Huntington Beach, CA from July 1998-December 2001 were analyzed with respect to their spatial patterns along 23 km of beach, and temporal variability on time scales from hourly to fortnightly. The majority of samples had bacterial concentrations less than, or equal to, the minimum detection limit, but a small percentage exceeded the California recreational water standards. Areas where coliform bacteria exceeded standards were more prevalent north of the Santa Ana River, whereas enterococci exceedances covered a broad area both north and south of the river. Higher concentrations of bacteria were associated with spring tides. No temporal correspondence was found between these bacterial events and either the timing of cold water pulses near shore due to internal tides, or the presence of southerly swell in the surface wave field. All three fecal indicator bacteria exhibited a diel cycle, but enterococci rebounded to high nighttime values almost as soon as the sun went down, whereas coliform levels were highest near the nighttime low tide, which was also the lower low tide.

The increasing usage of sandy beaches as recreational resources has forced regional authorities of many tourist countries to remove all litter of fabricated origin and natural wrack from the beach. Consequently, a variety of heavy equipment has been developed during the last decades and is now used almost daily at many beaches. A field experiment, following a 'before-after-control-impact' (BACI) design, was conducted at the strandline of De Panne (Belgium) to investigate the impacts of mechanical beach cleaning on the strandline-associated meiofaunal assemblages, focussing on the free-living nematodes. Natural strandline assemblages were exposed to a one-off 5 cm deep mechanical beach cleaning and observed for 24 h. Differences between cleaned plots and those from control plots in terms of decreased percentage of organic matter, decreased total abundance and changed community structure were noticed from immediately after the experimental cleaning onwards and recovered to initial values after the following high water. Any impacts due to cleaning on species richness, Pielou's evenness and taxonomic diversity were shown to be minor in relation to the daily changes. Recolonization in the cleaned sediments is assumed to occur from the underlying sediments initiated by the elevated water table during the rising tide.

Beach health advisories are issued if enterococci (ENT) densities exceed the 30-d geometric mean or single-sample water quality criteria. Current ENT enumeration procedures require 1 day of incubation; therefore, beach managers make policy decisions using 1-day-old data. This is tantamount to using a model that assumes ENT density on day t is equal to ENT density on day t-1. Research has shown that ENT densities vary over time scales shorterthan a day, calling into question the usefulness of the current model for decision-making. We created Dynamic Partial Least Square Regression (DPLSR) models for ENT at water quality monitoring stations within two adjacent marine recreational sites, Huntington State Beach (HSB) and Huntington City (HCB) Beach, California, using publicly available environmental data and tested whether these models overcome the drawbacks of the current model. The DPLSR models provide a better prediction of ENT than the current models based on comparisons of root-mean-square errors of prediction and the numbers of type 1 and 2 errors. We compared outcomes in terms of predicted illness, swimmers deterred from entering the water, and net benefits to swimmers for hypothetical management scenarios where beach advisories were issued based on (a) the previously collected sample's ENT density in conjunction with the two water quality criteria, and (b) predictions from DPLSR models in conjunction with the single-sample standard. At both HSB and HCB the DPLSR scenario produced a more favorable balance between illness prevention and recreational access. The results call into question the current method of beach management and show that model-informed decision-making and elimination of the geometric mean standard will aid beach managers in achieving more favorable outcomes in terms of illness and access than are presently achieved using 1-day-old measurements, especially at beaches where water quality problems are chronic.

Analyses of Irish bathing water quality data sets are reported to investigate whether the parametric calculations proposed in the draft Bathing Water Directive are valid. Faecal coliforms (assumed to be Escherichia coli) and faecal streptococci (assumed to be intestinal enterococci) have been analysed separately. It was noted that classifications based on the parametric 95th percentile calculations disagreed with those based on percentage compliance with the standards on 13.8% of occasions. When these disagreements were studied, it was found that the datasets frequently contained many censored data points (Result < 1). Also, the datasets were not log normally distributed on at least 85% of occasions. Both these findings fatally undermine the validity of using a parametric method for calculating 95th percentiles to classify bathing water quality. By contrast the non-parametric Hazen method is a better estimate of true population 95th percentiles, but essentially gives very similar classifications to the percentage compliance approach, fully agreeing on over 95% of occasions. The same is also true when considering 90th percentiles. A series of Monte Carlo studies were also conducted to determine the impact of small numbers. It was ascertained that small sample sizes are very undependable in determining bathing water classification and the parametric method in particular is particularly unreliable. In conclusion, the parametric method for calculating bathing water compliance is so severely and fatally flawed statistically that it should not form the basis of any legislation. The Hazen method gives a better estimate of true 90th or 95th percentiles, though as the resultant classifications agree with percentage compliance so closely it is doubtful that there is any statistical value in using a percentile approach over the long established and well understood percentage compliance approach.

'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.

Gaza beach is the only recreational area available for the local inhabitants. It is heavily polluted with treated, partially treated, and untreated sewage from point and nonpoint sources. The majority of the population is below the age of 15 years. This age group is vulnerable to gastrointestinal diseases and usually restricts their activities to beach sand at the swash zone. Five sampling points along the Gaza beach were selected and monitored for 1 year (fortnightly). Microbial sand content was evaluated for fecal coliforms (FC), fecal streptococci (FS), Salmonella, Shigella, and Vibrio. Seawater samples were subjected to similar evaluation. Pseudomonas, yeast, and mold counts were performed for all sand samples as possible sand pollution indicators. Higher fecal indicators (both FC and FS) were obtained in sand than in water in most locations. The frequency of Salmonella and Vibrio isolation was also higher in sand than in water despite the fact that only 10 g of sand were used while 1L of seawater was collected. Statistically significant correlations between FC and streptococci and between Salmonella and Vibrio were found. Similar correlation was also detected between Pseudomonas and Salmonella in sand samples.

Marine beach water quality is typically monitored in early morning once a week without respect to tidal condition. To assess the effect of tide on this public health warning system, we analyzed enterococci (ENT) data from 60 southern California marine beaches with differing geomorphology, orientation, and proximity to runoff sources. ENT concentrations during spring tides were significantly higher (p < 0.1) than those during neap tides at 50 of the beaches, and at the majority of these, water samples were also more than twice as likely to be out of compliance with the ENT single-sample standard during spring tides compared to neap tides. When tide range (spring/neap) and tide stage (ebb/flood) conditions were considered together, spring-ebb tides yielded the highest ENT concentrations and the greatest chance of exceeding the single-sample standard at the majority of beaches. The proximity to a terrestrial runoff source, the slope of the runoff source, the slope of the beach, and the orientation of the beach had minimal influence on the tidal modulation of ENT concentrations. The presence of spring and spring-ebb tide signals at such a great percentage of beaches suggests that tide should be considered in the design and interpretation of beach monitoring program data. It also suggests that ENT delivered by tidally forced sources other than terrestrial surficial runoff are widespread. Possibilities include ENT-laden groundwater (saline and fresh) from the beach aquifer as well as ENT-enriched sands, decaying wrack, and bird feces near the high water line.