Water Quality Objectives Research Articles

Comparison of the presence and partitioning behavior of indicator organisms and Salmonella spp. in an urban watershed

The appropriateness of indicator organisms as surrogates for human pathogens in water quality modeling is dependent on similarities in both presence and transport behavior; however, very little data relating indicator and bacterial pathogen transport behavior in receiving waters is available. In this study observations of presence, partitioning behavior (i.e. association with settleable particles) and removal by upland detention basins were used to assess the suitability of six indicator organisms as surrogates for Salmonella spp. bacteria in an urban watershed. The fecal indicator bacteria (fecal coliforms, E. coli and enterococci) were most closely correlated with Salmonella in terms of presence and partitioning behavior (25–35% associated with settleable particles on average); however, further resolution of the variability associated with Salmonella partitioning is required. Higher removal of particle-associated microbes relative to the total microbial concentration by the detention ponds suggests that sedimentation may be an important removal mechanism. However, large fluctuations in pond performance between storm events and occasional net microbial exports in effluents indicate that these best management practices (BMPs), as currently implemented, will be unlikely to achieve water quality objectives.

Evaluation of surface water quality in waterways located in the municipality of Pelotas, RS, Brazil

The present work was performed in the municipality of Pelotas, RS, Brazil with the objective of evaluating water quality from the years of 1996 to 1998, in the principal waterways which pass through the municipality using the Water Quality Index of Bascaran (IQAb). It was verified that the water quality in the evaluated bodies was acceptable with the exception of the Eclusa and Santa Barbara reservoirs, in which phosphorus is the most important pollutant. During the period of prolonged drought from 1996 to 1997, there was a reduction in the IQAb. The index also reflected the environmental status verified in the region due to intensive agriculture and the release of a large portion of domestic and industrial wastes to the waterways without previous treatment.

Probabilistic reservoir operation using Bayesian stochastic model and support vector machine

Available water resources are often not sufficient or too polluted to satisfy the needs of all water users. Therefore, allocating water to meet water demands with better quality is a major challenge in reservoir operation. In this paper, a methodology to develop operating strategies for water release from a reservoir with acceptable quality and quantity is presented. The proposed model includes a genetic algorithm (GA)-based optimization model linked with a reservoir water quality simulation model. The objective function of the optimization model is based on the Nash bargaining theory to maximize the reliability of supplying the downstream demands with acceptable quality, maintaining a high reservoir storage level, and preventing quality degradation of the reservoir. In order to reduce the run time of the GA-based optimization model, the main optimization model is divided into a stochastic and a deterministic optimization model for reservoir operation considering water quality issues. The operating policies resulted from the reservoir operation model with the water quantity objective are used to determine the released water ranges (permissible lower and upper bounds of release policies) during the planning horizon. Then, certain values of release and the optimal releases from each reservoir outlet are determined utilizing the optimization model with water quality objectives. The support vector machine (SVM) model is used to generate the operating rules for the selective withdrawal from the reservoir for real-time operation. The results show that the SVM model can be effectively used in determining water release from the reservoir. Finally, the copula function was used to estimate the joint probability of supplying the water demand with desirable quality as an evaluation index of the system reliability. The proposed method was applied to the Satarkhan reservoir in the north-western part of Iran. The results of the proposed models are compared with the alternative models. The results show that the proposed models could be used as effective tools in reservoir operation.

Modeling of full-scale drinking water treatment plants with embedded plant control

In general, the available control actions in drinking water treatment plants are not directly related to the process objectives for water quality. Model based optimization of operation of a drinking water treatment plant by direct control of water quality objectives is discussed. Plant control with PID controllers is embedded in the model of a drinking water treatment plant and the ozonation process in the plant is used as a case study. It is concluded that direct control of water quality objectives, e.g. Giardia inactivation for ozonation, can largely reduce uncertainty and variation in process performance and leads to improvements of drinking water quality. In the discussed case it led to less bromate formation at the same disinfection capacity. Embedded plant control with PID controllers in the model of drinking water treatment plants through the use of code for writing control functionality has a large potential for model based optimization of operation.

Estimation of critical nutrient amounts based on input–output analysis in an agriculture watershed of eastern China

The concept of critical nutrient amounts (CNA) for a watershed was developed to address eutrophication in surface waters from diffuse (non-point) source pollution. CNA is defined as the maximum allowable applied or generated amount (AGA) of a nutrient from natural and human sources that can be emitted and still allow compliance with water quality standards. The CNA calculation method is based on properties of diffuse source pollution, including (i) estimation and analysis of nutrient input–output balances in terrestrial and riverine systems; (ii) prediction of terrestrial nutrient export loads and AGA using riverine loads; and (iii) calculation of critical AGA to meet different regulatory compliance locations (e.g., end of a reach or for the whole reach). The CNA concept was developed, validated and applied for total nitrogen (TN) and phosphorus (TP) in the ChangLe agriculture-dominated watershed (864 km 2/27.8 km reach) of eastern China. Results indicated that CNA was 7174 t N y −1 and 5004 t P y −1 for the reach-end control method and 8290 t N y −1 and 4425 t P y −1 for the whole-reach control method. Annual TN AGA exceeded CNA by 53.2–61.3% and 46.0–55.2% for reach-end and whole-reach control methods in 2004–06, respectively. In contrast, TP AGA values were 90.3–95.9% and 68.3–73.2% below CNA values for reach-end and whole-reach control methods, respectively. These calculations provide a target or permissible nutrient amount that can be used to develop management practices that allow attainment of water quality objectives at the watershed scale.

The effects of dissolved organic carbon, acidity and seasonality on metal geochemistry within a forested catchment on the Precambrian Shield, central Ontario, Canada

Metal pollution, in combination with other environmental stressors such as acid deposition and climate change, may disturb metal biogeochemical cycles. To investigate the influence of dissolved organic carbon, acidity and seasonality on metal geochemistry, this study has described concentrations of 19 metals as they pass through an acidified forested catchment on the Precambrian Shield in south-central Ontario, Canada. Metal, dissolved organic carbon (DOC) and sulphate (SO4 2−) concentrations fluctuate throughout the catchment compartments as the water passes through and interacts with vegetation, soils and bedrock. Relationships among metals, DOC and SO4 2− are most pronounced in compartments where DOC and SO4 2− exhibit high variability, namely in the throughfall, organic horizon soil water, and wetland-draining stream. Metal, DOC and SO4 2− concentrations varied seasonally in the streams, and temporal coherence occurred among metal, DOC and SO4 2− concentrations in the organic horizon soil water and the wetland-draining stream (PC1). In the wetland-draining stream, the highest DOC, Cr, Cu, Fe, Pb, and V concentrations occur in the summer, whereas concentrations of SO4 2− and most other metals peak in the fall after a period of drought. Despite the rural location, provincial water quality objectives for surface water were exceeded for many metals when the peak fall values occurred.

Water Quality Improvement Policies: Lessons Learned from the Implementation of Proposition O in Los Angeles, California

This article evaluates the implementation of Proposition O, a stormwater cleanup measure, in Los Angeles, California. The measure was intended to create new funding to help the city comply with the Total Maximum Daily Load requirements under the federal Clean Water Act. Funding water quality objectives through a bond measure was necessary because the city had insufficient revenues to deploy new projects in its budget. The bond initiative required a supermajority vote (two-thirds of the voters), hence the public had to be convinced that such funding both was necessary and would be effective. The bond act language included project solicitation from the public, as well as multiple benefit objectives. Accordingly, nonprofit organizations mobilized to present projects that included creating new parks, using schoolyards for flood control and groundwater recharge, and replacing parking lots with permeable surfaces, among others. Yet few, if any, of these projects were retained for funding, as the city itself also had a list of priorities and higher technical expertise in justifying them as delivering water quality improvements. Our case study of the implementation of Proposition O points to the potentially different priorities for the renovation of urban infrastructure that are held by nonprofit organizations and city agencies and the importance of structuring public processes clearly so that there are no misimpressions about funding and implementation responsibilities that can lead to disillusionment with government, especially under conditions of fiscal constraints.

Community uses and values of water informing water quality improvement planning: a study from the Great Barrier Reef region, Australia

Community participation has gained widespread recognition in water management and planning for its potential to inform management plans and gain community support for actions that are aligned with the community’s water values. However, the practical application of community participation remains challenging as there is no consensus on who should be involved and why. During a participatory research project to inform the Tully Water Quality Improvement Plan (WQIP), the local community was involved in qualitative interviews and workshops to identify the water uses and values in the Tully basin. The results showed that these waters are extensively used and valued via a wide range of activities and that water is more than an economic good. All participants valued the aquatic ecosystems, which provide the basis for setting the most stringent water quality objectives (WQOs). Moreover, the results showed that many of the current uses and values of waters are under serious threat and that some uses and values have been lost over time. These findings informed the setting of the WQOs for the Tully WQIP to protect and re-establish the water uses and values that the local community supports.

A New Approach to Water Quality Objectives: Development of a Tissue-Based Site-Specific Objective for a Bioaccumulative Pollutant

A New Approach to Water Quality Objectives: Development of a Tissue-Based Site-Specific Objective for a Bioaccumulative PollutantSince 2004, a group of over 20 stakeholders have been implementing a comprehensive program to address sources of nitrogen and selenium in the Newport Bay watershed in Orange County, California. The collaborative, stakeholder driven effort, the Nitrogen and Selenium Management Program (NSMP), included the development of a site-specific objective (SSO) for selenium. A tissue-based SSO has been...Author(s)Karen CowanEarl ByronSamuel LuomaTheresa PresserGary SantoloHarry OhlendorfSourceProceedings of the Water Environment FederationSubjectSession 13 - Site-Specific Objectives and Appropriate Use DesignationsDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2009ISSN1938-6478SICI1938-6478(20090101)2009:6L.984;1-DOI10.2175/193864709793958642Volume / Issue2009 / 6Content sourceTMDLS ConferenceFirst / last page(s)984 - 1006Copyright2009Word count137Subject keywordsSeleniumSite-Specific ObjectiveWatershedTMDLNewport BayCaliforniaFishBirdsTissue-Based Standard

Investigation of river eutrophication as part of a low dissolved oxygen total maximum daily load implementation

In the United States, environmentally impaired rivers are subject to regulation under total maximum daily load (TMDL) regulations that specify watershed wide water quality standards. In California, the setting of TMDL standards is accompanied by the development of scientific and management plans directed at achieving specific water quality objectives. The San Joaquin River (SJR) in the Central Valley of California now has a TMDL for dissolved oxygen (DO). Low DO conditions in the SJR are caused in part by excessive phytoplankton growth (eutrophication) in the shallow, upstream portion of the river that create oxygen demand in the deeper estuary. This paper reports on scientific studies that were conducted to develop a mass balance on nutrients and phytoplankton in the SJR. A mass balance model was developed using WARMF, a model specifically designed for use in TMDL management applications. It was demonstrated that phytoplankton biomass accumulates rapidly in a 88 km reach where plankton from small, slow moving tributaries are diluted and combined with fresh nutrient inputs in faster moving water. The SJR-WARMF model was demonstrated to accurately predict phytoplankton growth in the SJR. Model results suggest that modest reductions in nutrients alone will not limit algal biomass accumulation, but that combined strategies of nutrient reduction and algal control in tributaries may have benefit. The SJR-WARMF model provides stakeholders a practical, scientific tool for setting remediation priorities on a watershed scale.

Development and application of a species sensitivity distribution for temperature‐induced mortality in the aquatic environment

Current European legislation has static water quality objectives for temperature effects, based on the most sensitive species. In the present study a species sensitivity distribution (SSD) for elevated temperatures is developed on the basis of temperature sensitivity data (mortality) of 50 aquatic species. The SSD applies to risk assessment of heat discharges that are localized in space or time. As collected median lethal temperatures (LT50 values) for different species depend on the acclimation temperature, the SSD is also a function of the acclimation temperature. Data from a thermal discharge in The Netherlands are used to show the applicability of the developed SSD in environmental risk assessment. Although restrictions exist in the application of the developed SSD, it is concluded that the SSD approach can be applied to assess the effects of elevated temperature. Application of the concept of SSD to temperature changes allows harmonization of environmental risk assessment for stressors in the aquatic environment. When a synchronization of the assessment methods is achieved, the steps to integration of risks from toxic and nontoxic stressors can be made.

Information technology and innovative drainage management practices for selenium load reduction from irrigated agriculture to provide stakeholder assurances and meet contaminant mass loading policy objectives

Many perceive the implementation of environmental regulatory policy, especially concerning non-point source pollution from irrigated agriculture, as being less efficient in the United States than in many other countries. This is partly a result of the stakeholder involvement process but is also a reflection of the inability to make effective use of Environmental Decision Support Systems (EDSS) to facilitate technical information exchange with stakeholders and to provide a forum for innovative ideas for controlling non-point source pollutant loading. This paper describes one of the success stories where a standardized Environmental Protection Agency (EPA) methodology was modified to better suit regulation of a trace element in agricultural subsurface drainage and information technology was developed to help guide stakeholders, provide assurances to the public and encourage innovation while improving compliance with State water quality objectives. The geographic focus of the paper is the western San Joaquin Valley where, in 1985, evapo-concentration of selenium in agricultural subsurface drainage water, diverted into large ponds within a federal wildlife refuge, caused teratogenecity in waterfowl embryos and in other sensitive wildlife species. The fallout from this environmental disaster was a concerted attempt by State and Federal water agencies to regulate non-point source loads of the trace element selenium. The complexity of selenium hydrogeochemistry, the difficulty and expense of selenium concentration monitoring and political discord between agricultural and environmental interests created challenges to the regulation process. Innovative policy and institutional constructs, supported by environmental monitoring and the web-based data management and dissemination systems, provided essential decision support, created opportunities for adaptive management and ultimately contributed to project success. The paper provides a retrospective on the contentious planning process and offers suggestions as to how the technical and institutional issues could have been resolved faster through early adoption of some of the core principles of sound EDSS design.

An SF6 Tracer Study of the Flow Dynamics in the Stockton Deep Water Ship Channel: Implications for Dissolved Oxygen Dynamics

A sulfur hexafluoride (SF6) tracer release experiment was conducted in the Stockton Deep Water Ship Channel (DWSC) to quantify mixing and transport rates. SF6 was injected in the San Joaquin River upstream of the DWSC and mapped for 8 days. From the temporal change in SF6 distributions, the longitudinal dispersion coefficient (K x ) was determined to be 32.7 ± 3.6 m2 s−1 and the net velocity was 1.75 ± 0.03 km day−1. Based on the decrease in SF6 inventory during the experiment, the pulsed residence time for waters in the DWSC was estimated at ∼17 days. Within the DWSC from Stockton downstream to Turner Cut, dissolved oxygen concentrations maintained a steady state value of 4 mg l−1. These values are below water quality objectives for the time of year. The low flow rates observed in the DWSC and the inability of oxygen-rich waters from downstream to mix into the DWSC upstream of Turner Cut contribute to the low dissolved oxygen concentration.

Modeling Vadose Zone Processes during Land Application of Food‐Processing Waste Water in California's Central Valley

Land application of food-processing waste water occurs throughout California's Central Valley and may be degrading local ground water quality, primarily by increasing salinity and nitrogen levels. Natural attenuation is considered a treatment strategy for the waste, which often contains elevated levels of easily degradable organic carbon. Several key biogeochemical processes in the vadose zone alter the characteristics of the waste water before it reaches the ground water table, including microbial degradation, crop nutrient uptake, mineral precipitation, and ion exchange. This study used a process-based, multi-component reactive flow and transport model (MIN3P) to numerically simulate waste water migration in the vadose zone and to estimate its attenuation capacity. To address the high variability in site conditions and waste-stream characteristics, four food-processing industries were coupled with three site scenarios to simulate a range of land application outcomes. The simulations estimated that typically between 30 and 150% of the salt loading to the land surface reaches the ground water, resulting in dissolved solids concentrations up to sixteen times larger than the 500 mg L(-1) water quality objective. Site conditions, namely the ratio of hydraulic conductivity to the application rate, strongly influenced the amount of nitrate reaching the ground water, which ranged from zero to nine times the total loading applied. Rock-water interaction and nitrification explain salt and nitrate concentrations that exceed the levels present in the waste water. While source control remains the only method to prevent ground water degradation from saline wastes, proper site selection and waste application methods can reduce the risk of ground water degradation from nitrogen compounds.

Quantifying Diffuse Pollution Sources and Loads for Environmental Quality Standards in Urban Catchments

The paper explores the application of a unit area loading (UAL) approach to address the requirements of the US Clean Water Act (CWA) and the EU Water Framework Directive (WFD) for the identification and quantification of diffuse urban pollution sources. The UAL approach defines the spatial distribution of pollutant loadings within an urban catchment as a basis for the assessment of in-stream hazards and the implementation of source control BMP measures. Calculated annual outflow concentrations for a specific catchment for two pollutants, zinc and hydrocarbons, illustrate the different levels of dilution/control, which can be required to achieve receiving water quality standards and objectives. Methodological issues relating to traditional volume-concentration probabilistic modelling on which the UAL approach is based are discussed, and the application of the UAL approach to non-point diffuse pollution load management is reviewed.

Comparative analysis of regional water quality in Canada using the Water Quality Index

The Canadian Council of Ministers for the Environment (CCME) has developed a Water Quality Index (WQI) to simplify the reporting of complex water quality data. This science-based communication tool tests multi-variable water data against numeric water quality guidelines and/or objectives to produce a single unit-less number that represents overall water quality. The CCME WQI has been used to rate overall water quality in spatial and temporal comparisons of site(s). However, it has not been used in a comparative-analysis of exposure sites to reference sites downstream of point source discharges. This study evaluated the ability of the CCME WQI to differentiate water quality from metal mines across Canada at exposure sites from reference sites using two different types of numeric water quality objectives: (1) the water quality guidelines (WQG) for the protection of freshwater aquatic life and (2) water quality objectives determined using regional reference data termed Region-Specific Objectives (RSO). The application of WQG to the CCME WQI was found to be a good tool to assess absolute water quality as it relates to national water quality guidelines for the protection of aquatic life, but had more limited use when evaluating spatial changes in water quality downstream of point source discharges. The application of the RSO to the CCME WQI resulted in assessment of spatial changes in water quality downstream of point source discharges relative to upstream reference conditions.

Simulated response of water quality in public supply wells to land use change

Understanding how changes in land use affect water quality of public supply wells (PSW) is important because of the strong influence of land use on water quality, the rapid pace at which changes in land use are occurring in some parts of the world, and the large contribution of groundwater to the global water supply. In this study, groundwater flow models incorporating particle tracking and reaction were used to analyze the response of water quality in PSW to land use change in four communities: Modesto, California (Central Valley aquifer); York, Nebraska (High Plains aquifer); Woodbury, Connecticut (Glacial aquifer); and Tampa, Florida (Floridan aquifer). The water quality response to measured and hypothetical land use change was dependent on age distributions of water captured by the wells and on the temporal and spatial variability of land use in the area contributing recharge to the wells. Age distributions of water captured by the PSW spanned about 20 years at Woodbury and >1,000 years at Modesto and York, and the amount of water <50 years old captured by the PSW ranged from 30% at York to 100% at Woodbury. Short‐circuit pathways in some PSW contributing areas, such as long irrigation well screens that crossed multiple geologic layers (York) and karst conduits (Tampa), affected age distributions by allowing relatively rapid movement of young water to those well screens. The spatial component of land use change was important because the complex distribution of particle travel times within the contributing areas strongly influenced contaminant arrival times and degradation reaction progress. Results from this study show that timescales for change in the quality of water from PSW could be on the order of years to centuries for land use changes that occur over days to decades, which could have implications for source water protection strategies that rely on land use change to achieve water quality objectives.

Implications of flexibility in European Community environmental law: exemptions from environmental objectives in the Water Framework Directive

The present article is a brief review of the legal characteristics of water quality objectives and legally permissible exemptions from these objectives, as enacted in the EC Water Framework Directive. Six different types of exemptions have been identified in total. These vary markedly in the legal premises of their feasibility, ranging from the set deadlines for the environmental objectives to application of less stringent environmental objectives for certain water bodies.

Wastewater desalination in Israel

Desalination of secondary effluents in Israel by use of advanced IMS technology has been considered as a major water supply option since different IMS technologies evolved in the last several years for a variety of desalination applications like desalination of brackish surface, seawater and the more challenging — secondary wastewater. A comprehensive research work on advanced wastewater treatment at the Shafdan’s WWPT [Mekorot reclaims about 68% of Israel’s reused effluents for agriculture (190 out of 280 million cu.m./year) in several facilities, among which is the Shafdan-Dan Region Reclamation Plant — the largest of its type in the world], has been performed since 2000, when Mekorot started operating a pilot plant at this site. In the current research an innovative Zenon’s UF membrane (ZeeWeed®) performance is being evaluated. The wastewater reclamation experimental work aims at reaching two critical water quality objectives, COD and salinity, in a way that RO may be applied only to a part of the flow or even may not be required at all. The pilot scale investigations included operation of two UF technologies: encased and immersed, low fouling RO membranes, different types of antiscalants at different UF and RO operational parameters, such as flux, recovery, UF backwash and disinfection processing. The main objectives of the pilot studies are validation of the performance data specified by the system suppliers and optimization of the operating parameters to achieve the possible lowest cost. A general overview of Mekorot’s pilot studies is presented in the paper, including important results such as the data of operation at high recovery of up to 90% in presence of high organic loads and cost assessment of wastewater desalination in comparison with seawater desalination.

Inverse modeling of surface-water discharge to achieve restoration salinity performance measures in Florida Bay, Florida

The use of numerical modeling to evaluate regional water-management practices involves the simulation of various alternative water-delivery scenarios, which typically are designed intuitively rather than analytically. These scenario simulations are used to analyze how specific water-management practices affect factors such as water levels, flows, and salinities. In lieu of testing a variety of scenario simulations in a trial-and-error manner, an optimization technique may be used to more precisely and directly define good water-management alternatives. A numerical model application in the coastal regions of Florida Bay and Everglades National Park (ENP), representing the surface- and ground-water hydrology for the region, is a good example of a tool used to evaluate restoration scenarios. The Southern Inland and Coastal System (SICS) model simulates this area with a two-dimensional hydrodynamic surface-water model and a three-dimensional ground-water model, linked to represent the interaction of the two systems with salinity transport. This coastal wetland environment is of great interest in restoration efforts, and the SICS model is used to analyze the effects of alternative water-management scenarios. The SICS model is run within an inverse modeling program called UCODE. In this application, UCODE adjusts the regulated inflows to ENP while SICS is run iteratively. UCODE creates parameters that define inflow within an allowable range for the SICS model based on SICS model output statistics, with the objective of matching user-defined target salinities that meet ecosystem restoration criteria. Preliminary results obtained using two different parameterization methods illustrate the ability of the model to achieve the goals of adjusting the range and reducing the variance of salinity values in the target area. The salinity variance in the primary zone of interest was reduced from an original value of 0.509 psu 2 to values 0.418 psu 2 and 0.342 psu 2 using different methods. Simulations with one, two, and three target areas indicate that optimization is limited near model boundaries and the target location nearest the tidal boundary may not be improved. These experiments indicate that this method can be useful for designing water-delivery schemes to achieve certain water-quality objectives. Additionally, this approach avoids much of the intuitive type of experimentation with different flow schemes that has often been used to develop restoration scenarios.