Stormwater Discharges Research Articles

Preliminary environmental assessment of metal-contaminated sediment dredging in an Urban River, New Jersey, USA.

While several studies have reported success with remedial sediment dredging, the sustainability of these impacts remain unclear. This preliminary study aimed to investigate the short- and long-term effects of remedial dredging on metal contamination, dredging efficacy and ecological status of the Lower Passaic River. To accomplish this, pre- and post-dredging data were statistically analyzed and evaluated using geochemical indices. Short-term results showed effective heavy metal reduction although their concentrations became elevated in water column, increasing bioaccumulation risk in aquatic biota. On the long-term, metal concentrations increased in surface sediments. Ecological assessment revealed that Cu, Hg and Pb pose greater risks while Ag remained abundant despite dredging. Further investigation suggests that post-dredging residuals, surface runoff and sewage pollution may contribute significantly to recontamination and continued pollution. Depletion in long-term dredging efficacy from spring to summer suggest that season-influenced changes in temperature, algae growth and stormwater discharge may have played a role.

Characterization of Metal Pulsed Exposure to Aquatic Organisms with Post-Exposure Monitoring: Implications for Stormwater Exposure Assessment.

Freshwater organisms are often exposed to contaminants such as heavy metals from stormwater discharges, which are dependent on rainfall duration and intensity. Therefore, standardized (48- or 96-h) continuous exposure methods developed for whole effluent toxicity (WET) testing might not always accurately convey the effects of stormwater and runoff contaminants. The present study characterized the acute toxicity of copper (Cu), zinc (Zn), and cadmium (Cd) to freshwater amphipods (Hyalella azteca) and cadmium (Cd) to water fleas (Ceriodaphnia dubia) using a modified exposure design that integrated relevant pulsed durations and included post-exposure monitoring. Less than 24-h-old C. dubia and 7 to 8-day-old H. azteca were exposed to water spiked with Cu, Zn, or Cd using 6-, 12-, 26-, or 96-h durations under standard laboratory conditions and monitored for cumulative mortality and reproduction (C. dubia only). Lethal effect (LC10s, LC25s, LC50s) and reproductive effect (EC25s, EC50s) were determined based on either mortality or reproduction of organisms at the end of each pulse (6, 12, or 26 h) and at the end of their respective tests (96 h). For all metals exposed to each organism, acute toxicity was found to be highest for the (96 h) continuous exposures. For pulsed exposures, mortality continued to increase following transfer to clean water for post-exposure monitoring. These results indicate a latent effect of Cu, Zn, and Cd to H. azteca and Cd to C. dubia. The present study concluded that using the continuous (48- or 96-h) WET exposure method overestimates the effects of stormwater and runoff contaminants. However, pulsed exposures without post-exposure monitoring also underestimate the toxicity of contaminants. The proposed pulsed exposure design provides a compromise that is more realistic than current WET methods to assess impacts from episodic events and accounts for potential latent effects that may be overlooked without monitoring post-exposure. Environ Toxicol Chem 2022;41:2488-2499. © 2022 SETAC.

Evaluation of a sand filter material for road runoff treatment– pilot-scale field trial focused on copper and zinc removal

Abstract The effects of stormwater discharges on receiving aquatic environments and the need for their purification were highlighted by an EU court in May 2020. The ruling stated the need for removal of dissolved pollutants, which justifies field studies for development of far-reaching methods for runoff treatment. In this study, a standard sand was used as medium for road runoff filtration and removal of dissolved and particle-bound (<0.45 μm) zinc (Zn) and copper (Cu). Data included 24 road runoff events, mimicking the flow variations and pollutant emissions over a seven-month period. The findings showed that sand can be used to remove Zn and Cu from road runoff in a gravity fed treatment system at a surface load ranging from 16.8 to 201 L m−2 h−1. The removal of total Zn and Cu was 93 and 67%, respectively. Dissolved Zn was efficiently removed by the sand (87%), however not Cu (19%). The sand efficiently removed total suspended solids (TSS) from the maximum occurring 443 mg L−1 to below 5 mg L−1. No head loss due to the TSS loadings was observed. The sand's potential to remove the investigated metals was shown, but in the longer term, effluent concentrations may exceed permitted values.

Assessment of stormwater discharge contamination and toxicity for a cold-climate urban landscape

BackgroundStormwater is water resulting from precipitation events and snowmelt running off the urban landscape, collecting in storm sewers, and typically being released into receiving water bodies through outfalls with minimal to no treatment. Despite a growing body of evidence observing its deleterious pollution impacts, stormwater management and treatment in cold climates remains limited, partly due to a lack of quality and loading data and modeling parameters. This study examines the quality of stormwater discharging during the summer season in a cold-climate, semi-arid Canadian city (Saskatoon, Saskatchewan).ResultsSeven stormwater outfalls with mixed-land-use urban catchments > 100 km2 were sampled for four summer (June–August 2019) storm events and analyzed for a suite of quality parameters, including total suspended solids (TSS), chemical oxygen demand (COD), dissolved organic carbon (DOC), metals, and targeted polyaromatic hydrocarbons (PAHs). In addition, assessment of stormwater toxicity was done using the two toxicity assays Raphidocelis subcapitata (algae) and Vibrio fischeri (bacteria). Notable single-event, single-outfall contaminant pulses included of arsenic (420 µg/L), cadmium (16.4 µg/L), zinc (924 µg/L), fluorene (4.95 µg/L), benzo[a]pyrene (0.949 µg/L), pyrene (0.934 µg/L), phenanthrene (1.39 µg/L), and anthracene (1.40 µg/L). The IC50 in both R. subcapitata and V. fischeri was observed, if at all, above expected toxicity thresholds for individual contaminant species. Principal component analysis (PCA) showed no clear trends for individual sampling sites or sampling dates. In contrast, parameters were correlated with each other in groups including DOC, COD, TSS, and reduced algal toxicity; and total dissolved solids (TDS), sum of metals, and pH.ConclusionsIn general, stormwater characteristics were similar to those of previous studies, with a bulk of contamination carried by the first volume of runoff, influenced by a combination of rainfall depth, antecedent dry period, land use, and activity within the catchment. Roads, highways, and industrial areas contribute the bulk of estimated contaminant loadings. More intensive sampling strategies are necessary to contextualize stormwater data in the context of contaminant and runoff volume peaks.

Road runoff as a significant nonpoint source of parabens and their metabolites in urban rivers

Parabens are widely added to food, cosmetics, and medicines as preservatives and are typical contaminants of pharmaceuticals and personal care products (PPCPs). However, their fate and transport in urban watersheds remain largely unexplored. This study investigated the role of road runoff as a critical nonpoint source of parabens and their metabolites in urban rivers based on 73 multimedia (road runoff and dust in different urban land uses, wastewater, stormwater discharge and river water) samples collected from a highly urbanized drainage area. Seven parabens and five metabolites were detected in the road runoff, with mean concentrations of ∑parabens and ∑metabolites equal to 47.5 ng/L and 4710 ng/L, respectively. The concentrations in road runoff were comparable to those in treated wastewater and river water and showed a land use pattern of residential > industrial > commercial. A first flush effect of the contaminants was observed in a heavy rainfall event with an antecedent dry period. In general, the population-based and area-based emission intensities of ∑parabens and ∑metabolites in road runoff were one order of magnitude higher than those in wastewater effluent during the rainfall events. This study provides quantitative evidence that road runoff can be a major pollution source of parabens and their metabolites in rapidly growing cities during the wet season and calls for the integrated management of nonpoint sources to prevent urban river contamination by typical PPCPs.

Monitoring coliphages to reduce waterborne infectious disease transmission in the One Water framework.

Coastal waters, surface waters, and groundwater are impacted by wastewater and stormwater discharges, as well as agricultural flows containing animal waste and nutrients. A One Water approach posits that components of the water system have overlapping and interactive impacts on other aspects of the system, for which a comprehensive approach to water management is needed to further inform public health decisions. Current frameworks for monitoring wastewater effluent and recreational surface waters include the measurement of fecal indicator bacteria. Although viral pathogens are likely to be transported further and can survive longer than bacterial pathogens, virus monitoring is not required for recreational waters. A scientific consensus is emerging that the use of bacterial indicators alone does not account for nor represent the health risks associated with viral pathogens due to the differences in the fate and transport of bacterial versus viral pathogens in wastewater treatment, surface water, and groundwater. Furthermore, it is likely that the public health risk associated with these waterborne pathogens is variable and diverse. For example, under drought conditions, effluents of urban water systems can comprise most of the dry weather flow in downstream waters, which are often used as sources of drinking water. This de facto reuse could increase viral risk for the end users of this water. A One Water approach will aid in protecting the health of the public from waterborne pathogens, regardless of where those pathogens entered the water system. In this review, we assert that monitoring for fecal indicator viruses can complement the monitoring of bacterial indicators, thereby improving public health protections. Bacteriophages have the strongest research foundation and correlation with viral pathogens along with some prediction power for risk to human health. Methods for detecting and quantifying coliphages are briefly summarized, as are challenges in the implementation of testing. Key knowledge gaps and research priorities are discussed so that the potential value and limitations of coliphage monitoring can be better addressed and understood.

What roles do architectural design and on-site water servicing technologies play in the water performance of residential infill?

More than half of new urban residential developments are planned as infill in Australia's major cities. This provides an unprecedented opportunity to use innovative design and technology to address urban water challenges such as flooding, reduced water security and related infrastructure and urban heat island issues. However, infill can have positive or negative water impacts, depending on architectural design and on-site water servicing technologies implemented. In this study we asked, “What influence does residential infill development have on the local urban water cycle?” and “What roles do architectural design and technologies play?” To answer these questions, a set of 196 design-technology configurations were developed by combining 28 architectural designs and 7 on-site water-servicing technology options. The configurations represent three cases: (i) existing (EX) or before infill, (ii) business-as-usual development (BAU), and (iii) alternative development (ALT). Using the Site-scale Urban Water Mass Balance Assessment (SUWMBA) model and a set of water performance indicators, the impact of configurations on the urban water cycle was quantified. The results showed BAU, on average, increases population density, stormwater discharge, and imported water by 98%, 44% and 85%, and decreases evapotranspiration and infiltration by 53% and 34%, compared to the EX conditions. More population density (141%) with lower impacts on the urban water cycle (21% and 64% increase for stormwater discharge and imported water, and 29% and 17% reduction in evapotranspiration and infiltration) can be achieved by appropriate integration of ALT designs and technologies. Architectural design has a greater influence on urban water flows than the implementation of on-site water servicing technologies. The results have a great implication for sustainable urban water management for managing the risks associated with pluvial flooding, water insecurity, and urban heat. It also highlights the underutilised role of architects and urban planners to address urban water issues.

Species diversity and ecological features of the Voronezh reservoir algae

The work is devoted to the long-term study of the species diversity and ecological features of the Voronezh reservoir algae. The algological study revealed 228 species of algae belonging to 7 divisions, 14 classes, 38 orders, 60 families and 99 genera. Most species belong to the departments Bacillariophyta (110 species), Chlorophyta (60) and Cyanophyta (34). It has been established that most of the algae of the water reservoir have unicellular and colonial types of organization, spherical, pear-shaped or filamentous structures of the thallom, there are flagellar stages in life cycles. The largest number of taxa belongs to the groups of -mesosaprobionts (74), xenosaprobionts and oligo--mesosaprobionts (29). Planktonic algae are more common in the water reservoir (116), while benthic (62) and periphytic (50) are less common. The main factors contributing to the blooming of water in the Voronezh reservoir are shallow waters, discharge of untreated sewage and stormwater, elevated temperature. To solve this problem the following measures are proposed: a competent and systematic approach to reducing the pollution of the water reservoir, development of effective methods for regulating water quality, reducing the proportion of anthropogenic load on the reservoir, increasing the number of aquatic fauna, development of safe methods to improve the condition of the water area.

Investigation of polyethylene terephthalate (PET) drinking bottles as marine reservoirs for fecal bacteria and phytoplankton

Polyethylene terephthalate (PET) is frequently used in the food and beverage industry and therefore contributes greatly to plastic marine debris. The fecal pollution indicator bacteria Enterococcus is used for marine water contamination assessments and is regularly found in storm water discharge. In order to examine if PET drinking bottles act as refuges for Enterococcus, a study was conducted within euhaline tidal waters of Wrightsville Beach, NC, USA via the deployment of bottle floats positioned nearby two stormwater outfall pipes. Bottles were retrieved weekly to assess the accumulation of fecal bacteria and phytoplankton. Each bottle was analyzed for the presence of Enterococcus on plastic surfaces and within water inside the bottle. Abundance of Enterococcus and planktonic chlorophyll α was found to be significantly greater in association with PET bottles versus the surrounding waters. Bottles were observed to act as reservoirs for both Enterococcus and phytoplankton with concentrations well above the state, federal, and WHO standards.

Performance of commercially available soil amendments for enhanced Cu attenuation in bioretention media

Bioretention structures such as planter boxes, swales and rain gardens are being increasingly utilized in built landscapes as a strategy to attenuate both stormwater flows and contaminant loads. Copper (Cu) roofing materials contribute significantly higher mass loads of dissolved Cu per unit area than other surfaces such as parking lots and roadways. While a recent study demonstrated that conventional bioretention media can remove greater than 90% of Cu from copper roof runoff, the median Cu concentrations at the point of discharge from bioretention structures (66 μg L−1) still did not achieve Cu concentrations in stormwater discharges sought in some jurisdictions (for example, < 14 μg L−1). Consequently, commercially available soil amendments were assessed to improve bioretention Cu removal. The ability of biochar, greensand, and zeolite to improve Cu removal was evaluated in laboratory column studies. Additionally, the performance of zeolite as an underlayer amendment was evaluated in bioretention planter boxes treating stormwater from a picnic shelter with a partitioned copper roof. Cu was measured in the planter box influent and effluent. The field setup included 2 control planter boxes containing only standard bioretention media and 2 amended with the zeolite underlayer. Samples from ten storms were collected with flow-weighted composite sampling. Total Cu in composite samples of the influent waters ranged from 445 to 1683 μg L−1 and had a median concentration of 934 μg L−1. Total Cu in the effluent from the control planter boxes ranged from 10 to 64 μg L−1, with a mean of 29 μg L−1. Total Cu in effluent from the zeolite amended planter boxes ranged from 4 to 44 μg L−1 with a mean of 18 μg L−1. Attenuation in the control planter boxes ranged from 90 to 99% with a median of 93.4% by concentration and ranged from 95 to 99% with a median of 97.5% in the zeolite amended planter boxes.

Airborne transmission pathway for coastal water pollution.

Each year, over one hundred million people become ill and tens of thousands die from exposure to viruses and bacteria from sewage transported to the ocean by rivers, estuaries, stormwater, and other coastal discharges. Water activities and seafood consumption have been emphasized as the major exposure pathways to coastal water pollution. In contrast, relatively little is known about the potential for airborne exposure to pollutants and pathogens from contaminated seawater. The Cross Surfzone/Inner-shelf Dye Exchange (CSIDE) study was a large-scale experiment designed to investigate the transport pathways of water pollution along the coast by releasing dye into the surfzone in Imperial Beach, CA. Additionally, we leveraged this ocean-focused study to investigate potential airborne transmission of coastal water pollution by collecting complementary air samples along the coast and inland. Aerial measurements tracked sea surface dye concentrations along 5+ km of coast at 2 m × 2 m resolution. Dye was detected in the air over land for the first 2 days during two of the three dye releases, as far as 668 m inland and 720 m downwind of the ocean. These coordinated water/air measurements, comparing dye concentrations in the air and upwind source waters, provide insights into the factors that lead to the water-to-air transfer of pollutants. These findings show that coastal water pollution can reach people through an airborne pathway and this needs to be taken into account when assessing the full impact of coastal ocean pollution on public health. This study sets the stage for further studies to determine the details and importance of airborne exposure to sewage-based pathogens and toxins in order to fully assess the impact of coastal pollution on public health.

Statistical Analysis of Field-Based Stormwater Filtration Performance for the Ecosol Litter Basket

Increasing specificity in water quality regulations for the discharge of stormwater to the environment has increased the requirement to more accurately characterize the performance of filtration interventions. This work presents a statistical performance analysis for the Ecosol Litter Basket, an at source filtration device, based on an extensive field study. The field evaluation of the Ecosol Litter Basket, a primary stormwater filtration device, was performed over a three-year period in an urban catchment in Queensland, Australia. A total of 29 rainfall events were recorded, of which between 13 to 16 events were evaluated as qualifying for the purposes of characterizing the removal efficiency. A variety of pollutant removal evaluation metrics, including concentration-based and total load-based metrics, were utilized in this study to characterize the efficacy of the device for removing a range of pollutants. Two approaches are proposed to facilitate the analysis: a nonlinear regression approach to more effectively deal with nonlinear patterns in the influent and effluent data; and the regression of concentrations (ROC), which is an additional concentration-based metric. A statistical analysis of the results demonstrated that the differences between influent and effluent streams for TSS are significantly different in their mean and median, and the removal efficiency of the Ecosol Litter Basket was evaluated to be 57–65% for TSS with the influent event mean concentration (EMC) up to 142 mg/L.

Integrating culture and molecular quantification of microbial contaminants into a predictive modeling framework in a low-lying, tidally-influenced coastal watershed

Examinations of stormwater delivery in the context of tidal inundation are lacking. Along the coastal plains of the southeastern United States, tidal inundation is increasing in frequency and severity, often with dramatic adverse impacts on timely stormwater discharge, coastal flooding hazards, and even “sunny day flooding”. Therefore, a comprehensive study was conducted to examine tidally-influenced stormwater outfalls discharging to Taylor's Creek, an estuary proximal to Beaufort, NC used regularly for recreation and tourism. Over a wide range of meteorological conditions, water samples were collected and analyzed for fecal indicator bacteria (FIB, used for water quality management) and previously published quantitative microbial source tracking (qMST) markers. Nineteen sampling events were conducted from July 2017–June 2018 with samples classified according to tidal state and defined as either inundated, receding, or transition. A first-of-its-kind multiple linear regression model was developed to predict concentrations of Enterococcus sp. by tidal cycle, salinity and antecedent rainfall. We demonstrated that the majority of variability associated with the concentration of Enterococcus sp. could be predicted by E. coli concentration and tidal phase. FIB concentrations were significantly (<0.05) influenced by tide with higher concentrations observed in samples collected during receding (low) tides (EC: log 3.12 MPN/100 mL; ENT: 2.67 MPN/100 mL) compared to those collected during inundated (high) (EC: log 2.62 MPN/100 mL; ENT: 2.11 MPN/100 mL) or transition (EC: log 2.74 MPN/100 mL; ENT: 2.53 MPN/100 mL) tidal periods. Salinity, was also found to significantly (<0.05) correlate with Enterococcus sp. concentrations during inundated (high) tidal conditions (sal: 17 ppt; ENT: 2.04 MPN/100 mL). Tide, not precipitation, was shown to be a significant driver in explaining the variability in Enterococcus sp. concentrations. Precipitation has previously been shown to be a driver of Enterococcus sp. concentrations, but our project demonstrates the need for tidal parameters to be included in the future development of water quality monitoring programs.

From Pilot Projects to Transformative Infrastructures, Exploring Market Receptivity for Permeable Pavement in The Netherlands

Climate change and changing land use challenge the livability and flood safety of Dutch cities. One option cities have to become more climate-proof is to increase infiltration of stormwater into soil through permeable pavement and thus reduce discharge of stormwater into sewer systems. To analyze the market receptivity for permeable pavements in the Netherlands, this article focuses on the perception of end-users towards key transition factors in the infrastructure transformation processes. Market receptivity was studied on two levels: (1) on the system level, by analyzing 20 key factors in the Dutch urban water sector that enable wider application of permeable pavements; and (2) on the technology level, by analyzing 12 key factors that explain why decision makers select permeable pavements or not. Results show that trust between cooperating partners was perceived as the system level key factor that needs to be improved most to facilitate the wider uptake of permeable pavements. Additionally, the association of end-users with permeable pavement, particularly their willingness to apply these technologies and their understanding of what kinds of benefits these technologies could bring, was regarded the most important receptivity attribute. On the technology level, the reliability of permeable pavement was regarded as the most important end-user consideration for selecting this technology.

Quantitative assessment of biogenic elements and suspended matter load to inner-city river: the role of point sources and diffuse runoff

The article provides a quantitative assessment of the input of biogenic elements and suspended matter in the composition of the storm sewer outlets from the territory of the Kazan City (Russia, the Republic of Tatarstan) and the diffuse runoff of biogenic elements from the agro-developed catchments into the Kazanka River (left tributary of the Volga River) as the main risk factors for the development of anthropogenic eutrophication processes. Based on the results of long-term monitoring and the current background concentrations of total phosphorus, nitrogen and suspended solids in the recipient river, determined in the work, the impact of storm water discharge on surface waters within the Kazan City was assessed. The values of permissible loads of phosphorus and nitrogen mineral fertilizers on an agriculturally developed catchment are given for regulating the diffuse runoff of nutrients into a water body, depending on the hydrometeorological conditions of the territory, to a level that meets the basic environmental requirements for the quality of surface waters.

Evolutionary Transition of Stormwater Pump System in Tokyo

One of the roles of sewerage is to effectively discharge stormwater and protect urban areas from inland flooding, but there are several challenges to overcome. Urban development is progressing in Tokyo, and the amount of stormwater flowing into the sewers is increasing. In order to respond to the increase in the frequency of heavy rainfall in recent years, it is necessary to improve the capacity of stormwater pumps. The Bureau of Sewerage Tokyo Metropolitan Government has been working on the technological development of higher-performance stormwater pumps since the 1950s, when initial-type stormwater pumps were installed. The technological development history of stormwater pumps in Tokyo can be broadly divided into four periods. The first period spanned approximately 30 years when initial-type pumps, which start to operate after stormwater flows into the pump station, were active. In the second period, which spans approximately 20 years from 1980, two types of pumps were developed; a non-water supply pump that could operate reliably even in an earthquake, and a standby operation pump that could respond to sudden stormwater inflow during torrential rains. The third period spans approximately 15 years from 1999, when the waterless standby pump, which integrated the features of the two pumps developed in the second period, was developed and introduced. The fourth period is the era of pumps with higher performances than third period pumps developed after 2015. Currently, these stormwater pumps are operated together with a rainfall radar system that accurately grasps the rainfall situation and protects the citizens of Tokyo from inland flooding.

Freshwater input drives invasion success of exotic plants in saltmarsh communities

AbstractWhile saltmarsh communities are endangered in many parts of the world due to anthropogenic impact, the risk of invasion by exotic plants is considered to be low because of their saline conditions. However, in urban areas, saltmarshes receive high nutrient freshwater input through stormwater discharge. We tested if invasion of saltmarsh by exotic plant species was facilitated by increased nutrients and reduced salinity associated with urban stormwater input. In a manipulative glasshouse experiment, we grew saltmarsh communities under four treatments: high salinity–low nutrients (control), high salinity–high nutrients, low salinity–low nutrients and low salinity–high nutrients. We then invaded the saltmarsh communities with four common invasive exotic plants. Their survival rates were monitored weekly for seven weeks before final harvesting. All exotic species showed significantly higher survival in the ‘low salinity’ treatment compared to the ‘high salinity’ treatment. There was variability among species, with three of four having low survival rates (0–3%) under ‘high salinity’ conditions, while survival of Protasparagus aethiopicus was reduced to only 53–59%. Our findings suggest that under natural conditions of saltmarshes, the establishment of exotic plant seedlings is restricted. Additional freshwater increased the survival of invading exotic species significantly, whereas adding nutrients increased biomass production but not necessarily survival of exotics. However, the results can be highly species dependant as shown by the unexpected salinity tolerance of P. aethiopicus. Reduction in salinity of saltmarsh due to stormwater input facilitates invasion by exotic plant species that would otherwise be unable to tolerate the highly saline environment.

Poisk optimal'nogo raspolozheniya proyektiruyemykh vypuskov gorodskoy kanalizatsii v Sevastopol'skoy bukhte s pomoshch'yu chislennogo modelirovaniya i geoinformatsionnogo analiza

Numerous studies have shown that the current hydrochemical and hydrobiological state of the Sevastopol Bay has a negative impact on its biodiversity and recreational potential of the region. An increase in population and tourist flow, as well as plans for intense development of the coastal zone resources actualize the task of assessing the impact of the existing and planned configuration of the municipal sewage facilities on the most visited seashore areas and mariculture development. We propose a numerical method for calculating the function of influence of municipal sewage on the quality of the Sevastopol Bay water. Calculations were performed for the city beaches, esplanade of Primorsky Boulevard, piers and the mussel farm with various potential options of outfalls arrangement in mind. We have compared the data from available sources as to arrangement and character of the municipal sewerage outfalls. We have analyzed the connectivity between the known outfalls and areas where contaminated suspended matter is undesirable for each map of the influence function field. The analysis showed Ushakova Balka Beach to be the most susceptible to storm water and sewerage discharge. The areas near the berths on the Severnaya Side are strongly influenced by the immediately adjacent outfalls. Concentration of suspended matter released from the stormwater sewerage in the city center has a dramatic impact on the water condition at major places of recreation of city residents.

Successful mitigation of stormwater-driven nutrient, fecal bacteria and suspended solids loading in a recreational beach community

Marine and estuarine waterways adjacent to urban areas are often the final recipient of polluted stormwater runoff. Microbial degradation of coastal water quality is a direct threat to human health through fecal contamination of bathing waters and shellfish, as well as distressing local economies through the loss of waterways to commercial (shellfishing) and recreational use. In coastal waters reduction of nitrogen loading is a key strategy for prevention of noxious and toxic algal blooms. Best management practices (BMPs) can be successful tools for mitigating such pollutants in runoff, but BMPs must be tailored to individual situations for maximum effectiveness. This study examines the efficacy of a set of BMPs installed in the coastal resort Town of Wrightsville Beach, North Carolina, USA. The BMPs targeted the highly-impervious (90%+) drainage area of two stormwater outfall pipes emptying into recreationally used Banks Channel. Mitigation measures included replacement of impervious pavement with pervious concrete and construction of an infiltration chamber in the parking lot of a local recreational seaside club. Significant reductions were achieved in total stormwater discharge (62%), as well as loading of the fecal indicator bacteria Enterococcus (76%) and total nitrogen (TN – 87% decrease). Additionally, there were reductions in loading of total phosphorous (TP) and total suspended solids (TSS) to estuarine waters following BMP installment. The set of BMPs applied here have wide management applicability to coastal ecosystems, as well as freshwater riparian areas characterized by sandy, porous soils.

Particulate and Dissolved Organic Matter in Stormwater Runoff Influences Oxygen Demand in Urbanized Headwater Catchments.

Increasing inputs of organic matter (OM) are driving declining dissolved oxygen (DO) concentrations in coastal ecosystems worldwide. The quantity, source, and composition of OM transported to coastal ecosystems via stormwater runoff have been altered by land use changes associated with urbanization and subsequent hydrologic flows that accompany urban stormwater management. To elucidate the role of stormwater in the decline of coastal DO, rain event sampling of biochemical oxygen demand (BOD) in samples collected from the outfall of stormwater ponds and wetlands, as well as samples of largely untreated runoff carried by stormwater ditches, was conducted across a range of urban and suburban development densities. Sampling also included measurements of particulate and dissolved carbon and nitrogen, carbon and nitrogen stable isotopes, and chlorophyll-a. Results suggest stormwater may be a significant source of labile OM to receiving waters, especially during the first flush of runoff, even though BOD concentrations vary both among and within sites in response to rain events. BOD variability was best predicted by particulate OM (POM) and chlorophyll-a, rather than the larger pool of dissolved OM. These findings demonstrate the importance of managing episodic stormwater discharge, especially POM, from urbanized areas to mitigate DO impairment in larger downstream systems.