Water Quality Outcomes Research Articles

Case-based reasoning to support decision making for managing drinking water quality events in distribution systems

In order to better leverage past experience of water quality incidents, and to tap into the unique incident database currently being maintained and required by regulatory authorities, a data mining approach is herein proposed. The quality of drinking water is paramount to protecting public health. However water quality failures do occur, with some of the hardest to understand and manage occurring within distribution systems. In the UK, a regulatory process is applied in which water service providers must report on significant water quality incidents, their causes, actions and outcomes. These reports form a valuable resource that can be explored for improved understanding, to help with future incident management and evaluate potential solutions. Case-based reasoning is a knowledge-based problem-solving technique that relies on the reuse of past experience. The WaterQualityCBR software system presented here was developed as such a decision support tool to more effectively manage water quality in distribution systems.

Shifting drivers and static baselines in environmental governance: challenges for improving and proving water quality outcomes

Understanding the conditions that enable or constrain success in environmental governance is crucial for developing effective interventions and adapting approaches. Efforts to achieve and assess success in environmental quality improvement are often impeded by changes in conditions that drive outcomes but lie outside the scope of intervention and monitoring. We document how long-term changes in land use, agriculture, and climate act as non-stationary, shifting drivers of change that combine to render water quality management interventions less effective and increasingly difficult to assess. Focusing on the Yahara River watershed of south-central Wisconsin, USA, we ask how baselines influence program modeling, monitoring, and evaluation, as well as adaptation in governance approach. Through historical trend, GIS, and policy and qualitative data analyses, we find that changes in long-term land use and precipitation pattern dynamics exert tremendous pressure on water quality outcomes but are not captured in snapshot baseline assessments used in management planning or evaluation. Specifically, agricultural sector change related to the intensification of milk and manure production is increasingly challenging to address through best management practices, and flashier precipitation associated with climate change makes it difficult to achieve goals and establish a causal connection between management interventions and outcomes. Analysis of shifting drivers demonstrates challenges facing environmental governance in the context of climatic and social–ecological change. We suggest that goal setting, program design, and evaluation incorporate new modes of analysis that address slowly changing and external determinants of success.

Willingness to pay for BMP-induced water quality benefits and deviations around expected water quality outcomes

This paper investigates the economic valuation of the benefits accruing to farmers derived from expected water quality improvements stemming from the adoption of best management practices (BMPs). The study applies the stated-choice experiments administered on a sample of farmers located in the Chaudière and Etchemin watersheds just south of Quebec City to characterize the preferences of farmers in terms of the mean and standard deviation of phosphorus and coliform reductions, and the costs borne by local farmers and by taxpayers in the province of Quebec to support the adoption of BMPs. The results show significant observed and unobserved heterogeneity regarding farmers’ marginal utility of phosphorus and coliform reductions. The distribution of risk attitudes encompasses all three types: risk aversion, risk neutrality and risk loving. Benefit valuation decreases with age, but the age effect is smaller than the heterogeneity across farmers of a given age. Farmers experience disutility when their own cost or taxpayers’ cost increases, but a private dollar is worth substantially more to farmers than a public one.

Multiple imputation for assessment of exposures to drinking water contaminants: Evaluation with the Atrazine Monitoring Program

BackgroundDrinking water may contain pollutants that harm human health. The frequency of pollutant monitoring may occur quarterly, annually, or less frequently, depending upon the pollutant, the pollutant concentration, and community water system. However, birth and other health outcomes are associated with narrow time-windows of exposure. Infrequent monitoring impedes linkage between water quality and health outcomes for epidemiological analyses. ObjectivesTo evaluate the performance of multiple imputation to fill in water quality values between measurements in community water systems (CWSs). MethodsThe multiple imputation method was implemented in a simulated setting using data from the Atrazine Monitoring Program (AMP, 2006–2009 in five Midwestern states). Values were deleted from the AMP data to leave one measurement per month. Four patterns reflecting drinking water monitoring regulations were used to delete months of data in each CWS: three patterns were missing at random and one pattern was missing not at random. Synthetic health outcome data were created using a linear and a Poisson exposure–response relationship with five levels of hypothesized association, respectively. The multiple imputation method was evaluated by comparing the exposure–response relationships estimated based on multiply imputed data with the hypothesized association. ResultsThe four patterns deleted 65–92% months of atrazine observations in AMP data. Even with these high rates of missing information, our procedure was able to recover most of the missing information when the synthetic health outcome was included for missing at random patterns and for missing not at random patterns with low-to-moderate exposure–response relationships. ConclusionsMultiple imputation appears to be an effective method for filling in water quality values between measurements.

Upper washita river experimental watersheds: nutrient water quality data.

Climate variability, changing land use and management, and dynamic policy environments are the main reasons why long-term research is needed to understand and predict possible water quality outcomes to alternative future scenarios. Long-term water quality data sets are needed to address these water issues. Such data sets were acquired by the USDA-ARS in three watersheds in Oklahoma: the Southern Great Plains Research Watershed (SGPRW), the Little Washita River Experimental Watershed (LWREW), and the Fort Cobb Reservoir Experimental Watershed (FCREW). We provide: (i) a description of these water quality data sets, (ii) the sample collection and processing procedures used and an assessment of the data quality, (iii) summary analyses of the variability in each data set, and (iv) details about how to access these data sets. Water quality data collection in the SGPRW began in the 1960s and continued through 1978, while that in the LWREW covered the 1960s to 1990 period. Data collection began in the FCREW in 2004 and continues through the present. The data were collected from streams, unit source watersheds, groundwater wells, and reservoirs. The water quality data described for a given site are generally complete for a given period of record; however, not all sites were monitored continuously and were not necessarily analyzed for the same water quality parameters. These data sets are expected to improve modeling and assessments of conservation practices in relation to climate variability, land use changes, and other environmental factors and may be useful in developing strategies to mitigate these environmental impacts.

Development of a farmer typology of agricultural conservation behavior in the American Corn Belt

Farmers’ decisions about adopting conservation practices are inherently dynamic, affected by changes in environmental, economic, and social conditions, including interactions with other farmers. Water quality models that are used to assess agricultural policy interventions, such as the Soil and Water Assessment Tool (SWAT), lack the dynamic social component of farmer’s decisions. While agent-based models (ABM) can represent and explore these decision dynamics, ABMs have not been connected to water quality models that can measure environmental outcomes of farmer decisions. Connecting ABMs and SWAT could advance the development of targeted conservation policies. Toward this aim, we developed a typology of Corn Belt farmers based on farmer characteristics that could be employed in an ABM and be relevant to water quality outcomes. Because our typology was developed for use in an ABM and to link to an existing water quality model (SWAT), it had distinctive simplicity (to optimize utility of the ABM) and relevance to characteristics modeled by SWAT. To identify farmer characteristics, we reviewed the literature on conservation practices that could be represented in SWAT models and their adoption by Corn Belt farmers. We found that land tenure arrangements, farm size, source of income, and information networks were consistently identified as farmer characteristics that influence conservation practice decision-making, were simple and relevant. Employing these characteristics, we identified four types of farmers to populate an ABM that will be linked to SWAT: (1) “Traditional”: small operations relying primarily on on-farm income; (2) “Supplementary”: small operations relying primarily on off-farm income; (3) “Business-oriented”: medium to large operations relying primarily on on-farm income and well connected to information networks; (4) “Non-operator”: absentee and/or investor farmland owners with limited connection to local information networks. This typology represents the heterogeneity of Corn Belt farmers relevant to their adoption of conservation practices. It gives us the conceptual framework for an ABM that can be linked with SWAT to explore coupled social and biophysical processes within Corn Belt agroecosystems, focusing on alternative approaches to targeting conservation policy to effectively reduce sediment and nutrient runoff.

An investigation of water nutrient levels associated with forest vegetation in highly altered landscapes

Stream pollution by nutrient loading is a chronic problem in the Midwest, United States, and greater impacts on water quality are expected as agricultural production and urban areas expand. Remnant riparian forests are critical for maintaining ecosystem functions in this landscape context, allowing water infiltration and capture of nutrients before they are lost from the system. Our objective was to identify linkages between riparian forest plant com- munity composition and water quality in remnant forested headwater streams. We identified watersheds with embedded headwater streams in three land use categories: grazed, urban, and preserved. We assessed plant community composition and nutrient storage. We sampled the forest streams to monitor discharge rates and sediment, nitrogen (N), and phosphorus (P) loads. Herbaceous communities in preserved riparian forests had more native specialist species than urban or grazed sites. Plant N content was higher in preserved forests (17.6 kg ha -1 (15.7 lb ac -1 )) than grazed (12.5 kg ha -1 (11.2 lb ac -1 )) or urban forests (10.5 kg ha -1 (9.4 lb ac -1 )). Conversely, stream water total N delivery was higher in urban watersheds (0.043 kg ha -1 d -1 (0.038 lb ac -1 day -1 )) than preserved (0.026 kg ha -1 d -1 (0.023 lb ac -1 day -1 )) or grazed watersheds (0.02 kg ha -1 d -1 (0.018 lb ac -1 day -1 )). Stream water nitrate (NO 3 -N) concen- tration and total P delivery were highest for streams in urban areas. The most pronounced differences for plant composition and stream discharge and pollutant loads were between preserved and urban forests. Seasonal patterns were variable. We detected a weak negative but seasonally important relationship between plant N content and stream water N. We did not detect a similar relationship for P, which may indicate saturation of this nutrient in the watershed system. Detailed knowledge about relationships between land use, plant com- munity composition, and water quality outcomes could be used to target forest restoration efforts in landscapes highly impacted by humans.

What’s a Stream Without Water? Disproportionality in Headwater Regions Impacting Water Quality

Headwater streams are critical components of the stream network, yet landowner perceptions, attitudes, and property management behaviors surrounding these intermittent and ephemeral streams are not well understood. Our research uses the concept of watershed disproportionality, where coupled social-biophysical conditions bear a disproportionate responsibility for harmful water quality outcomes, to analyze the potential influence of riparian landowner perceptions and attitudes on water quality in headwater regions. We combine social science survey data, aerial imagery, and an analysis of spatial point processes to assess the relationship between riparian landowner perceptions and attitudes in relation to stream flow regularity. Stream flow regularity directly and positively shapes landowners' water quality concerns, and also positively influences landowners' attitudes of stream importance-a key determinant of water quality concern as identified in a path analysis. Similarly, riparian landowners who do not notice or perceive a stream on their property are likely located in headwater regions. Our findings indicate that landowners of headwater streams, which are critical areas for watershed-scale water quality, are less likely to manage for water quality than landowners with perennial streams in an obvious, natural channel. We discuss the relationships between streamflow and how landowners develop understandings of their stream, and relate this to the broader water quality implications of headwater stream mismanagement.

Opportunities for Reducing Total Maximum Daily Load (TMDL) Compliance Costs: Lessons from the Chesapeake Bay

The Chesapeake Bay Total Maximum Daily Load (TMDL) program is an unprecedented opportunity to restore the Chesapeake Bay, yet program costs threaten to undermine its complete implementation. Analyses of Bay TMDL program design and implementation were used to relate program cost-effectiveness to choices in (1) compliance definitions, (2) geographic load allocations, and (3) approaches to engaging unregulated sources. A key finding was that many design choices require choosing an acceptable level of risk of achieving water quality outcomes, and a lack of data can lead to precautionary choices, which increase compliance costs. Furthermore, although some choices managed costs, others decisions may have reduced the potential for cost savings from water quality trading and payment programs. In particular, the choice by some states to distribute the portion of load reductions that improve water quality in the Bay mainstem to many small basins is likely to diminish the potential for market development or reduce funding for the most cost-effective nutrient and sediment reduction practices. Strategies for reducing costs of future TMDLs include considering diminishing marginal returns early in the TMDL design to balance costs and risks in regulatory goal setting and to design rules and incentives that promote innovation and cost-effective compliance strategies.

PUMPS, GERMS AND STORAGE: THE IMPACT OF IMPROVED WATER CONTAINERS ON WATER QUALITY AND HEALTH

Applying a randomized controlled trial, we study the impact of improved water transport and storage containers on the water quality and health of poor rural households. The results indicate that improved household water infrastructure improves water quality and health outcomes in an environment where point-of-source water quality is good but where recontamination is widespread, leading to unsafe point-of-use drinking water. Moreover, usage rates of 88% after 7 months are encouraging with regard to sustainable adoption. Our estimates suggest that the provision of improved household water infrastructure could 'keep clean water clean' at a cost of only 5% of the costs of providing households with improved public water supply. Given the general consensus in the literature that recontamination of water from improved public sources is a severe public health problem, improved transport and storage technologies appear to be an effective low-cost supplement to the current standard of financing public water supply for poor rural communities.

Pairing a pilot plant to a direct filtration water treatment plant

This paper outlines experiments that were conducted to establish that statistically equivalent intermittent and finished water quality was demonstrated between pilot treatment trains and a corresponding full-scale plant (FSP). First, equivalence was successfully established between the two pilot trains using paired t tests to confirm that the two trains were producing statistically equivalent water quality (e.g., pH, turbidity) while operating under identical operational and process conditions. Secondly, hypothesized mean differences and paired t tests were effectively applied to confirm the water quality achieved following each treatment phase in the pilot plant mimicked the corresponding treatment process in the FSP. Successive trials demonstrated equivalence in multiple water quality parameters throughout the two treatment scales, including pH, UV254, total organic carbon, dissolved organic carbon, alkalinity, and turbidity. The validation process demonstrated that the pilot plant has the ability to reproduce water quality outcomes from the FSP and that the results of the pilot facility are representative of process changes that will optimize the FSP performance.

Landscapes Toolkit: an integrated modelling framework to assist stakeholders in exploring options for sustainable landscape development

At present, stakeholders wishing to develop land use and management change scenarios at the landscape scale and to assess their corresponding impacts on water quality, biodiversity and economic performance, must examine the output of a suite of separate models. The process is not simple and presents a considerable deterrent to making such comparisons and impedes the development of more sustainable, multifunctional landscapes. To remedy this problem, we developed the Landscapes Toolkit, an integrated modelling framework that assists natural resource managers, policy-makers, planners and local communities explore options for sustainable landscape development. The Landscapes Toolkit links spatially-explicit disciplinary models, to enable integrated assessment of the water quality, biodiversity and economic outcomes of stakeholder-defined land use and management change scenarios. We use the Tully–Murray catchment in the Great Barrier Reef region of Australia as a case study to illustrate the development and application of the Landscapes Toolkit. Results show that the Landscapes Toolkit strikes a satisfactory balance between the inclusion of component models that sufficiently capture the richness of some key aspects of social-ecological system processes and the need for stakeholders to understand and compare the results of the different models. The latter is a prerequisite to making more informed decisions about sustainable landscape development. The flexibility of being able to add additional models and to update existing models is a particular strength of the Landscapes Toolkit design. Hence, the Landscapes Toolkit offers a promising modelling framework for supporting social learning and adaptive management through participatory scenario development and evaluation as well as being a tool to guide planning and policy discussions at the landscape scale.

Economically viable land regeneration in Central Queensland and improved water quality outcomes for the Great Barrier Reef

The impact of excessive sediment loads entering into the Great Barrier Reef lagoon has led to increased awareness of land condition in grazing lands. Improved ground cover and land condition have been identified as two important factors in reducing sediment loads. This paper reports the economics of land regeneration using case studies for two different land types in the Fitzroy Basin. The results suggest that for sediment reduction to be achieved from land regeneration of more fertile land types (brigalow blackbutt) the most efficient method of allocating funds would be through extension and education. However for less productive country (narrow leaved ironbark woodlands) incentives will be required. The analysis also highlights the need for further scientific data to undertake similar financial assessments of land regeneration for other locations in Queensland.

Meeting Report: Knowledge and Gaps in Developing Microbial Criteria for Inland Recreational Waters

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

Getting to better water quality outcomes: the promise and challenge of the citizen effect

Agriculture is a major cause of non-point source water pollution in the Midwest. Excessive nitrate, phosphorous, and sediment levels degrade the Mississippi River and Gulf of Mexico. In this research we ask, to what extent can citizen involvement help solve the problem of non-point source pollution. Does connecting farmers to farmers and to other community members make a difference in moving beyond the status quo? To answer these questions we examine the satisfaction level of Iowa farmers and landowners with their current conservation measures as a proxy for willingness to change. A survey of 360 conservation minded farmers obtained from a random sample of 75 HUC (Hydrologic Unit Code) 12 Iowa watersheds reveals that 27% of the variance among farmers’ perception of adequacy of their conservation practices is explained by a combination of beliefs about the seriousness of water pollution, personal, civic, and expert connections. The more farmers talk with other farmers the more likely they are satisfied with their conservation efforts. However, the more frequently farmers talk to friends and neighbors that don’t farm, the more likely they are to not be satisfied with their conservation efforts. Further, the more social organizations farmers belong to—e.g., more non-farmers they interact with in a group setting—the more likely they are to be dissatisfied with their level of effort being adequate to protect local water bodies. These findings suggest the personal and civic connections among farmers and communities are important in explaining perceptions of how adequate conservation measures are. These perceptions have implications for farmers’ willingness to go beyond current actions and more actively engage in solving local watershed problems and explain why they may not currently be engaged in additional actions.

The Role of Civic Structure in Achieving Performance-Based Watershed Management

Traditional solutions to solving the problem of non-point source pollution from agricultural sources have been to write and enforce regulatory rules and create top-down financial incentives to shift land use practices. What has been overlooked are the roles that social pressure and internal beliefs and knowledge play in achieving sustainable practices. In this research, a model for achieving and sustaining targeted water quality outcomes is developed. A case study is used to illustrate how the civic structure and social connections among farmers in a common watershed provide an effective strategy for creating performance-based goals that can lead to better water outcomes.

Modeling Riverine Nitrate Export from an East‐Central Illinois Watershed Using SWAT

Reliable water quality models are needed to forecast the water quality consequences of different agricultural nutrient management scenarios. In this study, the Soil and Water Assessment Tool (SWAT), version 2000, was applied to simulate streamflow, riverine nitrate (NO(3)) export, crop yield, and watershed nitrogen (N) budgets in the upper Embarras River (UER) watershed in east-central Illinois, which has extensive maize-soybean cultivation, large N fertilizer input, and extensive tile drainage. During the calibration (1994-2002) and validation (1985-1993) periods, SWAT simulated monthly and annual stream flows with Nash-Sutcliffe coefficients (E) ranging from 0.67 to 0.94 and R(2) from 0.75 to 0.95. For monthly and annual NO(3) loads, E ranged from -0.16 to 0.45 and R(2) from 0.36 to 0.74. Annual maize and soybean yields were simulated with relative errors ranging from -10 to 6%. The model was then used to predict the changes in NO(3) output with N fertilizer application rates 10 to 50% lower than original application rates in UER. The calibrated SWAT predicted a 10 to 43% decrease in NO(3) export from UER and a 6 to 38% reduction in maize yield in response to the reduction in N fertilizer. The SWAT model markedly overestimated NO(3) export during major wet periods. Moreover, SWAT estimated soybean N fixation rates considerably greater than literature values, and some simulated changes in the N cycle in response to fertilizer reduction seemed to be unrealistic. Improving these aspects of SWAT could lead to more reliable predictions in the water quality outcomes of nutrient management practices in tile-drained watersheds.

Hydrologic Regions for sizing Stormwater Treatment Measures in Victoria

Designing stormwater treatment measures generally requires a continuous simulation modelling approach using a small time step to properly consider the influence of a range of local storm characteristics and hydrologic conditions. This can be a complex and costly exercise and requires both technical expertise and the availability of a suitably long period of rainfall data. This paper describes the development of a simple but rigorous procedure to transpose known performance data from one geographic location to another within the state of Victoria in Australia. The procedure is based on continuous modelling of the performance of a number of stormwater treatment measures using 6 minute rainfall recorded over a suitably long period for 45 sites across Victoria. The size of the treatment measures required to attain prescribed water quality outcomes for each of the sites investigated is determined from application of the model. These data are then normalised and correlated to geographic and meteorological characteristics of the individual sites to enable regional relationships to be derived. Five hydrologic regions within Victoria and a further four regions for the metropolitan region in Melbourne were delineated. Their corresponding regional formulae are applicable for all sites within Victoria.

Drip irrigation water and salt flow model for table grapes in Coachella Valley, California

Unlike annual crops where reclamation leaching of salts can be readily conducted between cropping, leaching of salts in permanent crops that are drip irrigated pose challenges. A need exists to formulate and test a management-type of salinity model for drip irrigation of table grapes. The model reported herein predicts the distribution of salts along the vine row and between the rows during the growing season, as affected by reactivity of salts of the applied irrigation water as well as rate and duration of drip application. The calibrated model reproduced the initial field salinity profiles after repeated irrigation cycles by adjusting only the routing factor α which is the ratio of horizontal to vertical water flow. After eight cycles the profiles stabilized and the calibrated horizontal to vertical flow routing ratio was 0.6. There is remarkable agreement between measured and simulated salinity. Corresponding soil moisture profiles show the expected high water content with depth at the emitter, the decrease in surface water content with radial distance and the increase with depth, at the distal end of the wedge. Although the model is location specific it can be applied knowing soil, initial and boundary conditions, as well as irrigation application quantity and quality and as such can be applied location by location in order to assess flow and quality of deep percolation recharging the groundwater system. With this capacity the model can predict soil water quantity and quality outcomes for possible land and water management scenarios.

The potential contribution of the Queensland Wet Tropics Region Natural Resource Plan to river improvement and water quality

This paper reports on work in progress on the new Wet Tropics Regional Natural Resource Management Plan and its potential to deliver river management and water quality outcomes. The plan is being prepared in accordance with the guidelines of the Nation Action Plan for Salinity and Water Quality/Natural Heritage Trust (NAP/NHT2). In particular the paper discusses the technical basis for priorities, target setting and implementation and the most effective instruments for achieving river improvement and water quality outcomes in the region.