Coastal Bacteria and Stormwater Runoff

The significant health issues correlated with urban stormwater runoff discharged into coastal waters is of prominent concern within the Orange County coastal zone of southern California because it is one of the most developed areas in the United States, and consequently, it produces some of the most highly polluted runoff. This study focuses on the improvements observed within Huntington and Newport beaches, since they have an unfortunate history of human illness related to their contaminated waters. A study by Given (2006) et al.,revealed the unhealthy effect these waters had on more than five million people who swam at the two beaches from 1998 to 2000—it showed record of about 36,000 cases of stomach ailment and 38,000 cases of respiratory, eye and ear infections caused by exposure to the polluted waters. Fortunately, water conditions within the area have displayed improvement. An initial increase of fecal bacteria concentrations was observed between the years of 2000 to 2005 (indicating poor water quality); however, bacteriological concentrations decreased during the period between 2005 and 2010 (indicating improved water quality). Lim and Jeong (2012) discovered that the stormwater runoff from the surrounding urban watershed is a primary source of fecal pollution in Orange County Beaches, so they inquired that efforts to improve water quality and protect beach-goers from pollution will likely have greater efficacy during wet weather periods than any other time of year. In addition, the study identified the effect of alongshore surf zone current on fecal pollution caused by coastal waves; moreover, their analysis elucidated methods to improve public health protection through management that is in compliance with coastal water quality standards.—Genevieve Heger
Lim, S., Jeong, Y. 2012. Decadal Trend of Coastal Water Quality in Orange County Beaches and Management Efficacy at Improving Public Health Protection. Journal of Environmental Science and Engineering A. 1: 967-979

Lim and Jeong conducted an extensive study of the water quality conditions at Huntington and Newport beaches. The site was divided into four stations (two per beach), and each was analyzed for concentrations of fecal indicating bacteria(FIB)–total coliform (TC), fecal coliform (FC), and enterococci bacteria (ENT)–between the decade of 2000 to 2010. The bacteriological data was analyzed using a defined substrate test known as IDEXX Colilert-18, and Enterolert. Empirical Orthogonal Functions (EOF) analyses in addition to periodogram analyses (using Matlab computer program) were also carried out for each of the three FIB. The precipitation records for the local area were obtained from a rain gauge at John Wayne Airport in the City of Santa Ana, which is approximately 23 kilometers northeast of the study site. Lifeguards kept record of wave conditions, including both direction and height of breaking waves (twice per day, once at 7:00 and again at 14:00 local time).
Lim and Jeong concluded that TC concentrations were significantly correlated with rainfall, while FC and ENT concentrations were somewhat correlated. It was also observed that all FIB concentrations were above average during the January-February-March period (i.e. winter months), which is when most rain falls in southern California. This observations correlates with their discovery that the coastal area exhibits an annual return period. Lastly, they found through observation of wave conditions, that contaminants are transported parallel to shore by wave-driven currents, in a direction (upcoast or downcoast) controlled by the approaching wave field. Lim and Jeong’s discoveries suggest a prospect for further water quality improvement.
Reference:
Given, S, Pendleton, L.H., Boehm, A.B.  2006. Regional public health cost estimates of contaminated coastal waters: A case study of gastroenteritis at southern California beaches, Environmental Science and Technology. 40: 4851-4858.

Fecal Bacteria off Southern California Beaches

Semenza (2012) et al. found that the concentrations of fecal bacteria in the waters off the coast of  coast of three major counties  (Los Angeles, Santa Monica, and San Diego) in Southern California have a direct correlation to the intensity of rain events in the surrounding areas. Higher concentrations of bacteria are observed after higher intensity rainfalls have occurred. In light of this correlation, it was predicted that disease burdens, such as gastrointestinal illness, skin, ear, eye, and nose infections, due to the high levels of fecal bacteria concentration in the water (as a result of large amounts of discharged unfiltered urban stromwater runoff) may decrease because of ongoing climates changes that project hotter and drier weather conditions. Less rain would imply less runoff, which should result in lower concentrations of bacteria and lower risk of disease. Despite the projected decline in rainfall, by 416%, it is still unclear how certain the disease burden is predicted to decrease since chances of high variability are recorded for future weather patterns.—Genevieve Heger

                  Semenza, J. C., Caplan, J. S., Buescher, G., Das, T., Brinks, M. V., Gershunov, A. 2012. Climate Change and Microbiological Water Quality at California Beaches. EcoHealth 9, 293–297
                  Semenza et. al derived a linear model of microbiological water contamination (mean Enterococcusconcentrations) for 78 southern California beaches using Enterococcus and precipitation data. Data collected between 20002004 were used for estimations, and data from 2005 were used as validation. Enterococcusdata from Brinks et al. 2008 were also used. Predictions for future Enterococcuswater contamination levels were determined after projected precipitation levels were derived from the CNRM CM3 global climate model under the SRESA2 ‘business-as-usual’ scenario (IPCC 2007), which was downscaled for Huntington Beach using bias-corrected constructed analogues (BCCA). The annual means for projected Enterococcus levels were computed and the data were grouped by decade for the twenty-first century. Disease burden, as a result of projected contamination levels, were modeled according to two published dose–response relationships.
                  Precipitation was significantly related to measured Enterococcusconcentration between 2000-2004. A projected decrease in precipitation levels by 416% suggest that a relative decrease in coastal water contamination may occur, which provides a positive implication for infectious disease burden among recreational water users. However, due to the large variance in the empirical water quality and projected precipitation data, and differences in the dose response curves, we concluded that it is currently difficult to accurately predict disease burden.
Reference:
Brinks MV, Dwight RH, Osgood ND, Sharavanakumar G, Turbow DJ, El-Gohary M, et al. (2008) Health risk of bathing in southern California coastal waters. Archives of Environmental & Occupational Health 63(3):123–135

Dune Infiltration Systems for Reducing Stormwater Discharge to Coastal Recreational Beaches

The present issues related to untreated stormwater are significant and must be taken seriously, not only for the sake of aquatic ecosystems where this polluted water is discharged, but also for the sake of human health. After a rainfall, the concentration of fecal bacteria entering coastal waters, as a result of unfiltered discharged runoff, often exceeds the state and federal bacteria limits that are considered safe for human contact; and unfortunately, everyday beach-goers are ignoring the eminent health threats that these waters pose. Direct human contact with the stormwater or the area that receives its discharge can lead to symptoms of gastrointestinal, respiratory, ear, eye, nose and skin infections; yet, contact with discharging stormwater still occurs, despite visible warnings.  Previous studies have shown success capturing bacteria from stormwater using sand filters, so Burchell and his colleagues (2012) arranged the idea of a Dune Infiltration System (DIS) to divert stormwater from existing pipes and into dunes, where the water can be filtered through sand and ground water before it is discharged to the coastal waters. They constructed three DISs in Kure Beach, North Carolina for demonstrational study, and found that the performance of these systems was more successful than expected and that they are a low-cost and low-tech solution for diminishing stormwater discharge and associated fecal bacteria to recreational beaches. –Genevieve Heger
            Burchell, M., Hunt, W., Price, W. D., 2012. Dune Infiltration Systems for Reducing Stormwater Discharge to Coastal Recreational Beaches. Bio&Ag Engineering, 400-412

            Burchell et. al constructed DISs at three distinct sites in Kure Beach, North Carolina—site L, M, and K. Hundreds of samples were collected from each site, in addition to a controlled dune, where no DIS was installed. The fecal bacteria concentrations for each of the samples were measured and compared with the concentrations found in ground water outside the system in order to determine the effects of the DIS. The efficiency of the DISs in North Carolina underwent both short-term and long term monitoring to ensure the stability and reliability of these systems.
            They found that overall, the DISs were a success. The concentration of bacteria was reduced by 98%. Nearly all of the runoff that was generated at the three sites was treated in the DIS before entering the ocean waters. Site L demonstrated 100% stormwater capture, site M demonstrated 96%, and site K demonstrated 80%. The percent captured for site K, although lower than the others, is understandable since it received greater volumes of runoff with higher concentrations of bacteria than the other two sites. The systems appeared to have no negative effects, and the authors believe that the incorporation of these systems may receive positive media coverage and could potentially boost tourism.

Comparison of recreational health risks associated with surfing and swimming in dry weather and post-storm conditions at Southern California beaches

Urban stormwater runoff serves as indirect transportation for pollutants of all kinds, and it contributes to the high levels of fecal bacteria contamination within coastal waters, posing a potential threat to ordinary beach goers. Eight popular beaches in Southern California underwent quantitative microbial risk assessments (QMRA) to determine the concentration of fecal indicator bacteria (enterococcus, ENT and fecal coliform, FC), and gauge the significant dangers associated with activity in these waters—specifically the risk of acquiring a gastrointestinal illness (GI) while engaged in surfing or swimming. Tseng and Jiang (2012) evaluated the difference in potential health risks between surfers and swimmers, and surveyed the corresponding threat level throughout the two distinct Southern California seasons—dry season (characterized with less than two inches of total rainfall) and storm season, which accounts for 90% of the annual rainfall. They found that higher health risks were present during storm season as opposed to dry season, and that surfers were more susceptible to illness. –Genevieve Heger
Tseng, L. Y., and Jiang, S. C., 2012. Comparison of recreational health risks associated with surfing and swimming in dry weather and post-storm conditions at Southern California beaches using quantitative microbial risk assessment (QMRA). Marina Pollution Bulletin 6, 912918

Tseng and Jiang selected eight beaches from three coastal counties based on the following criteria: popularity among surfers, proximity to weather stations, and availability of bacteriological monitoring data. Bacteriological monitoring data were collected from the responsible agency within each county, and daily precipitation data were gathered from the National Climate Data Center (NCDC) National Environmental Satellite throughout the months of January 2008 to May 2012.
Because the study strived to compare the degree of potential health risk between dry and storm season, the following terms were defined: “post-storm” is the period between 24 and 72 hours after a recorded rainfall of greater than 0.2 inches, ‘‘dry weather’’ was defined as the dates with either no recorded precipitation, or a time period of at least 72 hours following a recorded rainfall. FIB data were excluded from analysis on the dates of missing precipitation information, and on the days of recorded precipitation because the exact time of the FIB sample collection was not reported (which could have been either be before or after the rain).
In order to assess the difference in health risk between surfers and swimmers, ingested doses of seawater were estimated and evaluated for concentrations of harmful bacteria (fecal coliform and enterococcus) to determine the likelihood of acquiring a GI due to such exposure. The ingested dose of ENT or FC by surfers was given by the equation, Doral = Ioral *C, where Doral is the ENT or FC dose ingested (MPN or CFU), Ioral is the ingested seawater volume by surfers (ml), and C is the seawater concentration of ENT or FC (MPN/ml or CFU/ml). Surfer’s risk of GI from ENT was estimated by applying the exponential dose-response model (Haas et al. 1999 Stone et al. 2008), and their risk of GI from FC was estimated by applying the Beta-Poisson model (Haas et al.1999). For the comparison, the ingested seawater volume in ml by swimmers is given by the equation, Ioral;swim = T exposure   *Ringestion ; where Ioral, swim is the ingested seawater volume by swimmers,  Texposure  is the time of swimming (minutes), and Ringestionis the water volume rate of ingestion in (ml/min).
Overall, the study showed that health risks were elevated during storm season as opposed to dry season. At Santa Monica, El Segundo, San Diego and Coronado beaches, health risk associated with surfing at post-storm conditions was significantly elevated (p 0.1). It was also noted that post-storm surfing could exceed EPA risk guidelines up to 28% of time, while the chance of exceeding the risk guideline during dry weather conditions was mostly below 15% based on the ENT model. The study also indicated that the risk of GI per in-seawater event was higher for surfing than for swimming, which was attributable to the increased volume of contaminated water ingested.
Works Cited:
1. Haas, C.N., Rose, J.B., Gerba. C.P., 1999. Quantitative Microbial Risk Assessment. Wiley, New York 

Biofilters for Stormwater Harvesting: Understanding the Treatment Performance of Key Metals That Pose a Risk for Water Use

The concept of recycling nontraditional water sources like stormwater is becoming increasingly popular as the quality and quantity of natural water resources continue to be depleted. A practical method of treatment has not been set in play, however, because affordable technology is yet to deliver promising results. There have been good results for biofiltration systems, specifically in the treatment of polluted stormwater discharges that enter receiving waters and affect aquatic health. Biofilters have effectively removed pollutants and harmful chemicals to meet aquatic health standards and protect the ecosystems of receiving waters; however, very little study has been done to address the capacity of biofiltration for treating water to the standard of human use (and consumption). The behavior of iron—its impact on taste and color—are of particular concern. Feng et al. (2012) constructed multiple biofiltration systems—varying the plant species used (C. appressa, D. revolute, M. stipoides, L. brownii, and M. ericifolia), filter media types and depths (300, 500, and 700 mm), inflow volumes (50, 25, and 12.5 L ), and concentrations of pollutants—to optimize the removal of iron and other toxic metals and pollutants so that the required drinking water standards may be met. They found that vegetation and filter type were significant to the treatment of metals, and that larger filter media depths increased the outflow of toxic metals; they concluded that biofilters can be developed as viable water treatment systems that remove iron and meet the required drinking water standards.—Genevieve Heger
            Feng, W., Hatt, B. E., Fletcher, T. D., Deletic, A. 2012. Biofilters for Stormwater Harvesting: Understanding the Treatment Performance of Key Metals That Pose a Risk for Water Use. Environ. Sci. Technol. 5100–5108

            Feng et al.constructed several biofilter columns using various plant species (C. appressa, D. revolute, M. stipoides, L. brownii, and M. ericifolia), filter media types and depths (300, 500, and 700 mm), inflow volumes (50, 25, and 12.5 L), and concentrations of pollutants. To simulate storm events of the area, synthetic stormwater was prepared and volumes equivalent to 4.53 mm rainfall depths (1 in 4 month average for Melbourne) were dosed into the constructed columns twice a week between June 2006 and April 2007. Approximately every seven weeks, the outflow samples from each column were collected and analyzed for concentrations of metals (Fe, Pb, Cu, Zn, Al, and Cr), total suspended solids, and nutrients. The hydraulic conductivity of each column was also measured, and the results were estimated based on Darcy’s law. The data were analyzed by comparison with reference to Australian guidelines of for drinking water (as well as for irrigation and protection of aquatic ecosystems).  Tukey or Tamhane’s posthoc tests were used to determine the significance difference of treatment performance between columns (e.g. filter media depth). Lastly, this model by Johnson et al. was used.
ln(Co/Ce
1) = knM2rmediax/ 1E6 Cou * BV
[Where Co is the inflow concentration of pollutants (mg/L), Ceis the outflo concentration (mg/L), k is the rate constant (1/day), NMis the capacity of th filter media used (mg pollutant/g media),
rmedia is the saturated density of the filter media (g/m3), x is the filter depth (m), u is te unit loading rate (m/day), and BV is the total volume treated divided by volume of media.]
The measured (Co/Ce
1)/ Co  value was plotted against the measured hydraulic conductivity to examine the impact pollutants had on outflow concentrations.
            In summary, the authors found that biofiltration systems pose treatment technology for delivering safe water into surrounding aquatic ecosystems, and meet the majority of Australian drinking water standards. Outflow concentrations of iron (0.3mg/L), and the removal of aluminum never seemed to reach the drinking water standard.
The variation of each component in the column proved a certain significance according to the data collected. Vegetation made significant difference in metal removal—C. appressa demonstrated good removal of iron, whereas M. ericifolia did not. Filter media type and depth also played a significant role in metal removal—vermiculate and perlite showed the best removal of zinc, where mulch and compost demonstrated great removal of aluminum and chromium, and it was concluded that larger media depths resulted in higher outflow of metals. Testing biofiltration performance under laboratory conditions is not entirely reflective of  of the system; however, it provides valuable insight and excellent evidence for further experimentation.

Inter-Storm Dissolved Organic Matter Variability and its Role in Microbial Transport during Urban Runoff Events

The harvest and reuse of stormwater is a current challenge, and one major concern is associated with the wide range of pollutants present in the stormwater runoff. The pathogens and chemicals that have been indentified in stormwater runoff impair the ecological health of receiving water bodies and pose significant human health risk, particularly microbial pathogens. These microbes attach to suspended particulate matter, particularly organic material for their transport. Aryal et al. (2012) investigated the relationship between organic matter present in stormwater and two specific microbes, Escherichia coli and Enterococcus spp, showing that the increase of hydrophilic organics and humic substances—such as dissolved organic carbon, sulfur, nitrogen, and oxygen—hindered the transportation of microbial pathogens present in the stormwater runoff. –Genevieve Heger
Aryal,R., Sidhu, J.P.S., Chong, M.N., Toze, S., Keller, J. , Gernjak, W. 2012. Inter-Storm Dissolved Organic Matter Variability and its Role in Microbial Transport during Urban Runoff Events. 18

Aryal et al. studied five stormwater events in South East Queensland throughout the months of March, April, and May, 2011. Stormwater samples were collected from the Fitzgibbon drain, which is a medium density residential urban catchment. A total of four wet weather samples (31 March, 4 April, 18 April and 30 May) and one dry weather sample (7 March 2011) were collected. The dry sample was collected by a grab sampling method, whereas the wet weather samples were collected using three automatic sampler methods (ISCO 6700 series). A submersible Argonaut Flow Doppler (Thermo Fisher Sci.) was installed to measure the stormwater flow, and the auto-samplers were programmed to fill up to 24 x 20 L high density polyethylene (HDPE) container (Food & Drug approved grade) during the storm duration. The collected stormwater samples were analyzed for faecal indicator bacteria within 10 hours of collection, and a portion of each sample was stored at 4oC to be chemically analyzed within a week.
The quantification of faecal indicating bacteria (FIB) was determined by the standard membrane filtration method, where samples were filtered though nitrocellulose filters, transferred to respective selective agar plates, incubated overnight, and finally counted to calculate the average number of colony forming units (cfu 100mL-1). The quantification and identification of organic matter was analyzed using UV spectrophotometry (Varian 50 Bio) scanning between 190-400 nm, in addition to liquid size exclusion chromatography with organic carbon detection (LC-OCD, DOC Labor, Dr. Huber) to determine dissolved organic fractions.
Results indicate that E. coli and Enterococcus spp. numbers were significantly higher during the wet period than the dry period. The dry weather showed the highest absorbance indicating a higher concentration of organics in the sample The E. coli numbers varied between 102 to 103 100 cfu mL-1 during the dry and wet periods whereas, the corresponding numbers for Enterococcus spp. varied between 102 to 104 cfu 100mL-1.
The data show some differences in the absorbance between the five events, which indicates variation in the concentration of dissolved organic matter. The dry weather sample showed the highest absorbance, indicating a higher concentration of organics. It was believed that the stagnant water in the drainage seemed to helped to release/decompose organics present in the bed sediment (Spellman 2009). Other samples showed a decrease in concentration from every runoff event to the next.

There was a negative correlation between the concentration of microbes and dissolved organic carbon, especially hydrophilic organic material. Within the hydrophilic fraction, humic substances hindered the FIB transport more than the other organics. Humic substances showed a negative correlation with microbial densities indicating that their presence may hinder the transportation of microbes. While it is made clear that a decrease of organic concentration favored the increase of FIB numbers in stormwater; the study suggests that further research is necessary to understand the influence of dissolved organic matter in microbes transport via stormwater.

Urban Stormwater Runoff: A New Class of Environmental Flow Problem

Protecting the ecological integrity of freshwater ecosystems in addition to providing reliable and affordable water supplies to the growing human population is an ongoing challenge to water resource management and environment flow assessment. Urban stormwater runoff from conventional drainage systems degrades the ecosystems of streams and rivers by altering their volume and flow, resulting in a loss of biodiversity and ecological function. In order to assess and resolve this issue, Walsh et al. (2012) identified experimental causes by urban stormwater runoff and observed ways that have been implemented ways to protect them. They concluded that conventional stormwater management would needed to be completely revamped. Walsh et al. (2012) proposed to mimic the effects of informal drainage systems, where runoff is well-dispersed within surrounding vegetation (gardens or forests) or harvested in rainwater tanks. By providing filtration and large detention systems.—Genevieve Heger
Walsh CJ, Fletcher TD, Burns MJ. 2012. Urban Stormwater Runoff: A New Class of Environmental Flow Problem. PLoS ONE 7, 17

Walsh et. al. studied four small streams in eastern Melbourne; two of which almost completely lacked conventional stormwater drainage (Sassafras and Olinda), and two for which conventional stormwater management was utilized (Little Stringybark and  Brushy). The effect of conventional stormwater drainage was determined by assessing the flow regime and discharge in all four sites. Flow regime was assessed using 6-minute-time-step flow data from a permanent flow gauge, in addition to a limited record of water depth that was collected using OdysseyTM capacitance water level probes, logging 5-minute intervals.  Discharge for Sassafras and Stringybark was estimated manually using either a CMC 20 current meter counter or a Marsh-McBirney flow-mateTM velocity meter, 6–10 times at each site, and for Olinda, discharge was estimated using a quadratic relationship between the discharge recordings from a permanent flow station downstream (Melbourne Water Station) and corresponding depth logger readings. Lastly, the increase in runoff volume generated by impervious surfaces was assessed in order to quantify the volume of urban stormwater runoff. Streamflow coefficients (mean annual discharge depth divided by mean annual rainfall) of undeveloped, unregulated streams were compared to impervious runoff coefficients (mean annual runoff depth from an impervious area divided by mean annual rainfall) in order to calculate the difference, which represented the loss of evapotranspiration and equated to the excess runoff generated.
From the data collected, it was observed that the informal drainage management of Sassafras and Olinda permit better retention and infiltration, preventing severe ecosystem degradation, whereas the conventional stormwater drainage systems of Little Stringybark and Brushy pass runoff and all its associated pollutants directly downstream. Thus ecosystem degradation in areas of conventional stormwater management can be improved by using informal drainage systems.