Environmental variables and their association with faecal coliform and faecal streptococci densities at thirteen Sydney beaches

Environmental variables and their association with faecal coliform and streptococci densities were investigated at a number of Sydney's metropolitan beaches. High variability in faecal coliform and faecal streptococci densities was observed at most beaches. The ability of the various models to explain the observed variation in faecal coliform or streptococci levels was relatively low, although they did provide an insight into the more influential environmental factors involved. Rainfall has the single most important effect on faecal coliform and streptococci densities at Sydney beaches. Whether this is due to increased stormwater runoff at the beaches, increased discharge through the outfalls (both the deepwater ocean outfalls and the few remaining shoreline outfalls), or a combination of both is unclear and is likely to depend on the individual beach being considered. Elevated levels of faecal coliforms and streptococci are still occasionally observed at some beaches, but these levels are usually not as high nor as frequent as they were prior to commissioning of the deepwater outfalls. The significant associations of current and plume entrapment with faecal coliform and streptococci densities at some Sydney beaches suggest that under certain conditions, effluent from the deepwater ocean outfalls can still influence faecal coliform and streptococci densities at these beaches.     

How do long-term patterns affect time-limited environmental monitoring programmes?

A five year Environmental Monitoring Programme (EMP) was set up in east-Australian coastal waters to determine the environmental effects of diverting most of Sydney's primary treated sewage from cliff face outfalls to diffuser outfall systems some 3 km offshore in 60–80 m of water. Many component EMP studies adopted Before and After Control Impact (BACI and ‘beyond BACI’) designs, to isolate outfall impacts on the marine ecosystem from background variability. Although seasonal patterns dominated ambient conditions in coastal waters, long-term climatic signals, such as the El Nino Southern Oscillation (ENSO), were apparent during the EMP. The Southern Oscillation Index (SOI) indicated the two year post-commissioning study period of 1991–1993 was dominated by an El Nino episode, while the 1989–1990 pre-commissioning period experienced a La Nina episode. Anomalous rainfall conditions and ocean temperature structure were associated with these episodes with respect to long-term records. Rainfall patterns suggested that the pre-commissioning period experienced high rainfall causing an increased incidence of stormwater pollution in coastal waters. Effects of the lower rain levels during post-commissioning phase were, however, outweighed by the dramatic improvements due to the commissioning of the deepwater outfalls. Decreased thermal stratification was experienced during the winter months of the 1992–1993 El Nino episode, and promoted increased dilutions associated with a greater frequency in sewage plume surfacing. There was, however, no apparent short-term effect of this change in plume behaviour on the marine environment as measured by EMP indicators.     

An overview of numerical modelling of the Sydney deepwater outfall plumes

In order to predict the behaviour of plumes from three deep ocean outfalls for sewage off Sydney, three-dimensional numerical modelling was used. The modelling suite was driven by data generated by an oceanographic monitoring station measuring wind, ocean currents, temperature and wave characteristics. Three different modelling phases are implemented daily, a nearfield model, a hydrodynamic model and a water quality model. Model output can be used by the New South Wales Environment Protection Authority to predict water quality at ocean beaches and inform the community.     

Microbiological water quality at non-human influenced reference beaches in southern California during wet weather

Although urban wet weather discharges may have elevated concentrations of fecal indicator bacteria impacting water quality at swimming beaches, not all of these bacteria may arise from human sources. In this study, the contribution of non-human fecal indicator bacteria was quantified by sampling coastal reference beaches in southern California. Samples were collected at beaches near stormwater discharges from undeveloped watersheds and analyzed for total coliform, Escherichia coli, and enterococci. Surfzone samples exceeded water quality thresholds >10 times more frequently during wet weather than dry weather. Exceedences were greatest <24 h following rainfall, then steadily declined on successive days. Early season storms exceeded thresholds more frequently, and by greater magnitude, compared to late season storms. Large storms exceeded thresholds more frequently than smaller-sized storms, partly due to the breaching of sand berms. When discharges did reach the surf zone, bacterial concentrations in the wave wash were correlated with watershed bacterial flux.     

Bacteriological water quality along the Tijuana-Ensenada, Baja California, México shoreline

This survey was part of a Binational Program (Mexico-United States) in microbiological water quality, with a goal to assess the shoreline bacteriological water quality from Tijuana to Ensenada, Mexico. Samples were collected at 29 sites (19 beaches and 10 outfalls), from the United States border to Punta Banda, Baja California, during summer (1998) and winter (1999). Total coliforms, fecal coliforms and enterococci were used as bacterial indicators. Standard methods were used for total and fecal coliforms, while the Enterolert quick method (IDEXX) was used for the enterococci. Compared with outfalls, the beaches exceeded water quality standards by a small percent, 25.3% in summer and 17% in winter. For outfalls, the percentage of shoreline that exceeded bacterial indicator thresholds had a minor value in summer (32.7%) than in winter (50%). Sites near wastewater discharges had the lowest quality and did not meet the microbiological water quality criteria for recreational use.     

Aquatic Ecological and Human Health Risk Assessment of Chemicals in Wet Weather Discharges in the Sydney Region, New South Wales, Australia

Sydney Water has completed a risk assessment to assess the risks to human health and aquatic organisms in creeks, rivers, estuaries and ocean waters affected by wet weather sewage overflows, stormwater and sewage treatment plant discharges. The risk assessment methodology consists of a comparison of measured and predicted concentrations of chemicals with toxicity reference values. Estimates of receiving water chemical concentrations were derived using data from a 10-year period so that the variable rainfall pattern was represented. Computer models were used to simulate and predict wet weather discharges during this ten year period. Risks were validated by bioassays and bioassessments. Risks to aquatic life from wet weather discharges were attributed to 14 chemicals at one or more of the sites and stormwater was the predominate source of the chemicals. There were no risks to people engaged in water based activities. Noncarcinogenic risks from fish ingestion are predicted at three sites. Predicted cancer risks for most individual chemicals were relatively small. Carcinogenic risks were typically associated with organochlorine compounds, polycyclic aromatic hydrocarbons, dichlorobenzene, and arsenic. The predicted cancer risks also appear to be largely the result of stormwater rather than sewage overflow inputs and largely due to historical contamination by organochlorine pesticides. It is expected the concentrations of these chemicals will decrease over time.     

‘Oyster watch’: Monitoring trace metal and organochlorine concentrations in Sydney''s coastal waters

This paper examines concentrations of trace contaminants in oysters placed in inshore and offshore waters before and after the change to offshore disposal of sewage near Sydney, NSW, Australia. The ability to compare inshore and offshore concentrations before and after the event allows the formulation of unconfounded conclusions about the impact of sewage on the availablity of trace contaminants in the coastal environment and the effect of the change in the method of disposal of Sydney's sewage on the availability of those contaminants.

The data show clearly that the diversion of sewage from nearshore to offshore areas has resulted in a significant drop in the concentrations of organochlorines in oysters deployed near sewage outfalls in the nearshore region. In offshore areas, there were no differences detected among regions prior to the commissioning of deepwater outfalls. In the post commissioning period there were a number of instances when trace metal concentrations in the regions were different from each other, but these differences were not correlated with proximity to the sewage outfalls nor was a particular metal consistently elevated, so it was concluded that the causes of difference were not related to the presence of the sewage outfalls.

This study has demonstrated that oysters were useful indicators of trace metal and organochlorine contamination of marine waters; that relatively high levels of contamination of inshore waters near sewage outfalls prior to deepwater sewage disposal were reduced, to be not different from other parts of Sydney's coastline after the commencement of deepwater discharge, and that there was no concommitant increase in accumulation of contaminants in offshore waters. Further, preliminary indications are that Sydney's coastal waters are not very heavily contaminated by trace contaminants in comparison to areas of NSW with much lower levels of development. Concentrations of organochlorines are, however, high in comparison to data from similarly developed areas of the USA.     

Effects of rainfall on microbial water quality on Qingdao No. 1 Bathing Beach,China

Limited by sampling frequency and detection methods, current recreational water monitoring programs often fail to protect public health, especially after heavy rain or flooding, when microbial water quality can change rapidly. In order to assess the variations in the microbial indicators and to develop a scientific warning system, we conducted an intensive sampling project at the No. 1 Bathing Beach. The results show that, during dry weather, the detection rate of Enterococcus was significantly lower than that of Faecal coliform bacteria. On these days, water quality was mainly impacted by pollutants brought in by swimmers than by stormwater outfall. During wet weather, rainfall and microbial bacterial concentrations showed a positive correlation. Trends in the two microbial bacteria were approximately the same. With increasing distance from the shore, the detection rate of microbial bacteria gradually decreased. Microbial bacteria concentrations increased markedly during high tide and under a south wind.     

Organochlorine compound and trace metal contaminants in fish near Sydney's ocean outfalls

Sydney's inshore sewage outfalls were significant contributors to organochlorine contamination of inshore sedentary fish such as red morwong. Diversion of the sewage to deepwater outfalls has resulted in marked declines in the concentrations of these compounds in inshore red morwong. Apart from lead, however, similar trends did not occur for concentrations of trace metals. A wide variety of trace metals and organochlorine compounds were found in the flesh and/or livers of a variety of fish species caught at sites associated with the present deepwater ocean outfalls off Sydney. Fish caught at locations remote from Sydney also contained a wide variety of trace metals although organochlorine compounds were usually at lower levels. The mean contaminant levels in all species of offshore fish were generally found to be low when compared to the Australian National Food Authority's Maximum Residue Limit (NFA MRL). No fish analysed was found to have levels of an organochlorine compound above the MRL and no fish was found to have levels of zinc or lead above the MRL. When detected, fish with levels of a trace metal above the MRL appeared to be distributed throughout New South Wales, independent of the deepwater ocean outfalls off Sydney. There is no evidence as yet that the commissioning of the deepwater outfalls has led to an increase in levels of contaminants in the fish examined to the extent that they are of concern relative to the NFA MRLs.     

Exposure to sewage plumes and the incidence of deformities in larval fishes

Point-source impacts such as sewage plumes can cause significant degradation of larval habitat. Data on larval abundance, current speed and the shape of surface and subsurface sewage plumes off the coast of Sydney, Australia, indicated that long-shore currents can transport large numbers of larvae through plumes that can potentially affect the health of larvae. Deformities to the notochord, eyes and head were found in samples of preserved wild larvae. Some deformities (e.g. Lateral curl of the notochord) were probably caused by preservation and ‘packing effects’ (shaped by organisms and objects in the sample), while others (e.g. half-pigmented eyes and corrugated notochord) were unlikely to have been caused by sampling artefacts. Deformed larvae were found in waters around Sydney that are influenced by multiple sewage outfalls, and at locations up to 250 km from Sydney. It was concluded that deformities were caused by natural and potentially anthropogenic factors. Cyto- and histopathological studies of larvae are required. Moreover, relationships between oceanography and concentrations of pollutants in plumes are needed to further assess impacts of pollutants on assemblages of vulnerable planktonic animals.     

Assessing impacts of deepwater sewage disposal: A case study from New South Wales, Australia

To overcome the problems of beach pollution Sydney Water constructed three deepwater sewage outfalls off North Head, Bondi and Malabar. The outfalls were commissioned over the period September 1990–July 1991. A 5-year multi-disciplinary environmental monitoring programme was set up to assess the impacts on the demersal fish and soft-bottom macro-invertebrate communities. Assessment of impact was based on an asymmetrical analysis of variance which provided an a priori orthogonal contrast between a single outfall and multiple control sites sampled before and after commissioning. Impacts were detected in both communities, included several commercially and recreationally important species of fish, and occurred with the greatest frequency in the soft-bottom community. The results are summarized, and several examples are presented and show that the direction and magnitude of the impacts varied among outfalls and taxa. The results are then discussed in terms of the needs of future monitoring and the implications for the assessment of human-induced impacts in other parts of the world.     

Sewage and the community—One view of Sydney's deepwater outfalls, the environmental monitoring programme and the future of sewage disposal

Sydney's sewage disposal problems have been the catalyst for wider questioning by the community about the management of the water cycle in the Sydney Basin. Public concern over the deepwater ocean outfalls generated an involvement in the Environmental Monitoring Programme (EMP) which provided a number of insights into the marine environment offshore Sydney, interactions between agencies and the role of public interest groups. The EMP has not provided sufficient information to make decisions about the value of higher levels of treatment. However, public interest in these outfalls is being subsumed by demands for the greater recycling of water and mechanisms for reducing water use.     

Metal contamination of sediments associated with deepwater ocean sewage outfalls, Sydney, Australia

The New South Wales Environment Protection Authority has recently completed a programme to evaluate the impact on near-shore shelf sediments, following the commissioning of three new deepwater sewage outfalls off Sydney, Australia. These outfalls discharge a total of around 1300 ML day⁻¹ of primary treated sewage derived from domestic and industrial sources. The study compared three locations that were close to the outfalls (likely impacted) and three locations far from the outfalls (likely non-impacted). Four zones were sampled within each location to provide estimates of spatial variability. Three samples of surface sediment were collected from each zone at six monthly intervals over a three year period which encompassed the commissioning of the outfalls. The results of the study suggest that, associated with the commissioning of the three deepwater outfalls, there has not been a significant effect on the concentration of trace metals in the sediments surrounding the outfalls. The concentrations of trace metals in the whole sediment generally were close to the world-wide background levels quoted in the literature, and generally reflected the distribution pattern of the sedimentary fines (< 62.5 mm). When compared to a number of sediment quality guidelines, the concentrations of trace metals were found to be below a level considered to have the potential to cause biological effects or (in the case of As, Ni, Cr) at a level that could be tolerated by the majority of benthic organisms.     

Baseline studies of delaware ocean outfall sites

A quarterly sampling programme was conducted during 1973–1974 off the coast of Delaware to provide an environmental baseline for two ocean sewage outfalls. Extensive physical measurements and water quality data, together with biological data (fish, invertebrates, bacteriological samples), were collected. Based on this research the design of sewage treatment for one of the outfalls was improved.     

NUMERICAL STUDY ON ENVIRONMENTAL IMPACTS OF THE THIRD SHANGHAI SEWERAGE PROJECT

1 INTRODUCTION Shanghai, Chinas largest metropolitan area with a population of about 14 million, is situated at the mouth of the Yangtze River, and bordered with the East China Sea to the east, Hangzhou Bay to the south, and the provinces of Zhejiang and Jiangsu to the west. It is a region with intensive distribution of rivers and lakes. The good geographic location and natural conditions have provided the city with superiority in its social and economic center and port city of the co…     

Subtidal assemblages on rocky reefs at a cliff-face sewage outfall (North Head, Sydney, Australia): What happened when the outfall was turned off?

For many years, sewage was continuously discharged via inshore outfalls into shallow subtidal habitats around Sydney (New South Wales). In 1990, deepwater ocean outfalls were commissioned and inshore discharge ceased. This study examined the assemblage of organisms found on subtidal cliffs at one inshore outfall to examine differences in, or recovery by, the biota when sewage was no longer discharged. This assemblage was primarily composed of filter-feeding animals (sponges, ascidians, bryozoans, anthozoans) and encrusting algae. Differences and changes in the assemblages at a number of different spatial scales, relative to the assemblages at two reference locations, were examined four times over a 20 month period. Although most taxa showed significant changes over the study period, most of these were unpredictable and varied interactively according to the taxon, plot, depth and location. For most measures, however, the location where sewage had been released lay within the natural variability shown by the reference locations. The implications of these findings are discussed with respect to other studies on the effects of sewage on intertidal and shallow subtidal habitats.     

Der Einfluss von Kläranlagenabwässern auf benthische Wirbellose im Zürichsee

In 1981–83 sublittoral macroinvertebrates were collected by means of SCUBA diving from artificial substrates submerged near the outfalls from eight sewage treatment plants in Lake Zürich. Pollution around the outfall resulted on the one hand in a reduction of pollution intolerant benthic invertebrates, on the other hand in a considerable increase in the relative abundance of pollution tolerant taxa such as leeches, flatworms and crustaceans. Changes in the faunal composition were related to nutrient enrichment and changes in the nature of the substratum due to sedimentation of sewage sludge. Species diversity (Simpson index) showed low values near the outfall from some plants, high values near the outfall from others. Low species diversity did not always mark the sites where greatest pollution has been observed.      

Distribution of enteric bacteria in Antarctic seawater surrounding the Port-aux-Français permanent station (Kerguelen Island)

Untreated sewage has been released from Port-aux Fran?ais station, Kerguelen Island, into the Southern Ocean for more than 50 years. We investigated the spatial distribution of faecal bacteria indicators during a one-year survey conducted in seawater off Morbihan Bay near the French permanent station of the Kerguelen Island (49 degrees 21(')S, 70 degrees 30(')E). Seawater samples were taken bimonthly from nine stations evenly distributed around the sewage outfalls of the station. Escherichia coli and enterococci were estimated using specific microplates (Miniaturized method for the enumeration of E. coli or enterococci in surface and waste waters, "MU/EC or MU/SF methods", BIO-RAD( Copyright)). In order to evaluate the role of seasonal changes of environmental parameters on the survival of enteric bacteria, total and saprophytic bacterial abundances were also estimated in all seawater samples. High densities of faecal bacteria (maximum 10(4) cells 100 ml(-1)) were found in seawater surrounding the sewage outfall. However, enteric bacterial counts decreased rapidly with increasing distance from the outfall. In all samples collected further than 2 km from the outfall, the bacterial indicators were absent or present in small numbers (<10 cells 100 ml(-1)). Faecal coliforms were not detected in samples collected at pristine sites located 10 km from Port-aux-Fran?ais. Despite these low contamination levels, faecal bacteria were always detected in the vicinity of the sewage outfall during the seasonal survey. The concentration of faecal bacteria may be related to the number of people inhabiting the station.     

Use of physiological responses in Mytilus trossulus as integrative bioindicators of sewage pollution

Mussels, Mytilus trossulus (average shell length 43+/-0.8 mm), were sampled from a beach in Alaska that received untreated sewage for several years, a second beach adjacent to a secondary wastewater outfall, and two nearby reference beaches. Survival time in air, byssal thread production rate, and prevalence of trematode parasites were determined for each group. Tolerances to aerial exposure was significantly lower (P<0.05) at both sewage outfall sites than at the reference sites. Mussels exposed to untreated sewage produced fewer byssal threads and had a significantly higher prevalence of encysted trematodes than mussels from the other beaches, including the secondary wastewater site. Survival in air, byssal thread production, and trematode prevalence in mussels may be useful indicators in evaluating the longterm health of beaches exposed to sewage.     

Nonlinear bacterial load‐streamflow response on a marine beach

Bacterial concentration (Escherichia coli) is used as the key indicator for marine beach water quality in Hong Kong. For beaches receiving streamflow from unsewered catchments, water quality is mainly affected by local nonpoint source pollution and is highly dependent on the bacterial load contributed from the catchment. As most of these catchments are ungauged, the bacterial load is generally unknown. In this study, streamflow and the associated bacterial load contributed from an unsewered catchment to a marine beach, Big Wave Bay, are simulated using a modelling approach. The physically based distributed hydrological model, MIKE‐SHE, and the empirical watershed water quality model (Hydrological Simulation Program – Fortran) are used to simulate streamflow and daily‐averaged E. coli concentration/load, respectively. The total daily derived loads predicted by the model during calibration (June–July 2007) and validation (July–October 2008) periods agree well with empirical validation data, with a percentage difference of 3 and 2%, respectively. The simulation results show a nonlinear relationship between E. coli load and rainfall/streamflow and reveal a source limiting nature of nonpoint source pollution. The derived load is further used as an independent variable in a multiple linear regression (MLR) model to predict daily beach water quality. When compared with the MLR models based solely on hydrometeorological input variables (e.g. rainfall and salinity), the new model based on bacterial load predicts much more realistic E. coli concentrations during rainstorms. Copyright © 2014 John Wiley & Sons, Ltd.