Data-driven models for predicting microbial water quality in the drinking water source using E. coli monitoring and hydrometeorological data

Rapid changes in microbial water quality in surface waters pose challenges for production of safe drinking water. If not treated to an acceptable level, microbial pathogens present in the drinking water can result in severe consequences for public health. The aim of this paper was to evaluate the suitability of data-driven models of different complexity for predicting the concentrations of E. coli in the river G\uf6ta \ue4lv at the water intake of the drinking water treatment plant in Gothenburg, Sweden. The objectives were to (i) assess how the complexity of the model affects the model performance; and (ii) identify relevant factors and assess their effect as predictors of E. coli levels. To forecast E. coli levels one day ahead, the data on laboratory measurements of E. coli and total coliforms, Colifast measurements of E. coli, water temperature, turbidity, precipitation, and water flow were used. The baseline approaches included Exponential Smoothing and ARIMA (Autoregressive Integrated Moving Average), which are commonly used univariate methods, and a naive baseline that used the previous observed value as its next prediction. Also, models common in the machine learning domain were included: LASSO (Least Absolute Shrinkage and Selection Operator) Regression and Random Forest, and a tool for optimising machine learning pipelines – TPOT (Tree-based Pipeline Optimization Tool). Also, a multivariate autoregressive model VAR (Vector Autoregression) was included. The models that included multiple predictors performed better than univariate models. Random Forest and TPOT resulted in higher performance but showed a tendency of overfitting. Water temperature, microbial concentrations upstream and at the water intake, and precipitation upstream were shown to be important predictors. Data-driven modelling enables water producers to interpret the measurements in the context of what concentrations can be expected based on the recent historic data, and thus identify unexplained deviations warranting further investigation of their origin

Impacts of environmental and hydrologic factors on urban stream water quality.

Urban streams can be impacted by a multitude of hydrologic and environmental factors, making maintaining these water sources difficult. Urbanization can exacerbate these impacts creating new challenges in preserving suitable urban stream water quality. Urbanization is the development of city landscape and suburban living within an otherwise natural region. For this environmental impact study, the effects of city development on urban stream water quality was monitored for Mill Creek in Louisville, Kentucky. To study the effects of urbanization on Mill Creek, this project was completed utilizing the BACI method for comparing impacts. The results of the water quality monitoring were acceptable for water quality standards in Kentucky in the categories of pH, water temperature, and conductivity from July 19th to August 14th of 2019. The dissolved oxygen concentration in the creek was below the standard for Kentucky regulations. The e. coli concentration of the studied creek were above regulations for state water quality standards in almost the entire stretch of Mill Creek (5 of 6 sampling locations). The e. coli was highest on the days of precipitation, while the dissolved oxygen was lowest in times of limited to no rainfall with rising temperatures. The e. coli concentration was a result of the high percentages of impervious pavements within the region leading to runoff of pollutants residing on urban surfaces. The dissolved oxygen was a result of reduced mixing of the water column in low flow with no rainfall. The conclusion was that urbanization is having an effect on these two parameters and will continue to deteriorate these water conditions if trends in city runoff and environmental destruction continue

Integrated Water Resources Research

Anthropogenic and natural disturbances to freshwater quantity and quality are a greater issue for society than ever before. To successfully restore water resources requires understanding the interactions between hydrology, climate, land use, water quality, ecology, and social and economic pressures. This Special Issue of Water includes cutting edge research broadly addressing investigative areas related to experimental study designs and modeling, freshwater pollutants of concern, and human dimensions of water use and management. Results demonstrate the immense, globally transferable value of the experimental watershed approach, the relevance and critical importance of current integrated studies of pollutants of concern, and the imperative to include human sociological and economic processes in water resources investigations. In spite of the latest progress, as demonstrated in this Special Issue, managers remain insufficiently informed to make the best water resource decisions amidst combined influences of land use change, rapid ongoing human population growth, and changing environmental conditions. There is, thus, a persistent need for further advancements in integrated and interdisciplinary research to improve the scientific understanding, management, and future sustainability of water resources

Proceedings of 2016 Kentucky Water Resources Annual Symposium

This symposium was planned and conducted as a part of the state water resources research institute annual program that is supported by Grant/Cooperative Agreement Number G11AP20081 from the United States Geological Survey. The contents of this proceedings document and the views and conclusions presented at the symposium are solely the responsibility of the individual authors and presenters and do not necessarily represent the official views of the USGS or of the symposium organizers and sponsors. This publication is produced with the understanding that the United States Government is authorized to reproduce and distribute reprints for government purposes

Dissémination des bactéries indicatrices de contamination fécale dans les hydrosystèmes tropicaux : transport et devenir d'Escherichia coli dans le bassin versant du Mékong au Laos

La contamination fécale des eaux de surface demeure une menace majeure pour la santé publique, en particulier dans les zones rurales des pays en développement. Les maladies diarrhéiques sont l'une des principales causes de décès notamment chez les enfants de moins de cinq ans, en raison de manque d'infrastructures sanitaires, et du faible accès aux ressources en eau salubre et aux soins médicaux. Plus de 70 millions de personnes dépendent de ressources en eau non améliorées dans le bassin inférieur du Mékong. Les progrès significatifs réalisés pour mieux comprendre la dynamique de la contamination fécale en milieu tempéré, de nombreuses lacunes subsistent en milieu tropical. Pour réduire la morbidité, il est nécessaire de mieux comprendre la dynamique des pathogènes fécaux surtout dans le contexte de changements globaux (croissance démographique, changements d'usage des terres, barrages hydroélectriques, et changement climatique). L'utilisation d'une approche multidisciplinaire est essentielle pour évaluer les risques contamination fécale à l'interface animal-homme-écosystème. L'objectif principal de la thèse est d'identifier les facteurs clés contrôlant le devenir et transport de la bactérie fécale indicatrice (FBI), Escherichia coli (E. coli), à différentes échelles spatiales des tributaires du Mekong au Laos. Cette thèse présente les résultats basés sur (i) les données in situ collectées dans les principaux tributaires du Mékong au Laos, afin d'identifier les facteurs (hydrologie et utilisation des terres) contrôlant les concentrations d'E. coli à l'échelle du bassin versant ; (ii) une approche expérimentale pour évaluer deux facteurs clés (rayonnement solaire et dépôt de particules en suspension) contrôlant la mortalié/survie d'E. coli dans une zone humide tropicale montagneuse; et (iii) des approches statistiques et de modélisation pour évaluer l'impact d'un barrage hydroélectrique sur la dynamique hydro-sédimentaire et d'E. coli dans un tributaire majeur du Mékong, la Nam Khan, au Laos. Les résultats des campagnes de mesures in situ ont révélé des variabilités saisonnières des concentrations d'E. coli dans les cours d'eau, plus élevées pendant la saison humide, et fortement corrélées aux concentrations en matières en suspension (MES) et aux pourcentages de forêts exploitées à l'échelle du bassin versant. Ces résultats soulignent le rôle des MES en tant que vecteurs pour le transport bactérien, ainsi que l'importance de des usages des terres comme l'un des facteurs clés ayant un impact sur la dissémination d'E. coli à l'échelle du bassin versant dans un contexte tropical érosif. La majorité des tributaires échantillonnés présentaient des concentrations d'E. coli pendant la saison des pluies, dépassant 500 colonies par 100 ml, seuil au-delà duquel l'OMS considère que le risque de maladie gastro-intestinale après une seule exposition est de 10 %. Le rôle des MES a été mis en évidence dans l'approche expérimentale, où les bactéries attachées à des particules étaient prédominantes (91%) et présentaient des taux de mortalité plus faibles que ceux des bactéries sous forme libre. Alors que le processus de dépôt était le principal facteur de réduction du stock d'E. coli dans la colonne d'eau, comparé aux radiations solaires, nous avons constaté que la remise en suspension temporaire des sédiments déposés suggérait un potentiel de survie ou même de croissance d'E. coli dans les sédiments en milieu tropical. Enfin, étant donné l'importance de la dynamique hydro-sédimentaire sur la dissémination bactérienne, nous avons évalué l'impact du barrage, reflété par des diminutions brutales en termes de débit (en moyenne de 42%), et les concentrations en MES et E. coli (en moyenne de 89%) mesurées en aval du barrage. Cette approche fournit de nouvelles preuves de l'atténuation de la contamination bactérienne induite par le barrage. Dans l'ensemble, ces résultats de thèse fournissent de nouvelles informations sur la dynamique des FBI dans le bassin inférieur du Mékong, qui pourraient être utiles dans l'établissement des stratégies efficaces de gestion des ressources en eau.Fecal contamination of surface water remains a major threat to public health especially in the rural areas of developing countries. Diarrheal diseases are a leading cause of death especially among children under age five, due to inadequate sanitation infrastructure, low access to safe water resources, and poor medical care in developing countries. Over 70 million people depend on unimproved water resources in the lower Mekong basin stretching from southern Chinese border to the delta in southern Vietnam. Despite the significant advances made towards a better understanding of the fecal contamination dynamics in temperate regions, yet many knowledge gaps exist in tropical conditions. Reducing the disease burden, requires a better understanding of fecal pathogens dynamics in the context of rapid global changes, e.g. population growth, land use changes, hydropower dam constructions, and climate change. Therefore, the use of a multi-disciplinary approach is essential to adress existing and potential risks of fecal contamination at the animal-human-ecosystems interface. The main objective here was to identify key factors controlling the fate and transport of the fecal indicator bacteria (FIB), Escherichia coli (E. coli), at different spatial scales of major Mekong tributaries in Lao PDR. This research work presents the results from (i) in-situ data collected from major Mekong tributaries from northern to southern Lao PDR aiming to identify main factors (hydrology and land use) controlling the in-stream E. coli concentrations at watershed-scale; (ii) experimental approach to assess two key factors (solar radiation exposition and suspended particles deposition) controlling E. coli decay/survival in a mountainous tropical headwater wetland; and (iii) statistical and modeling approaches to assess the impact of hydropower dam on hydro-sedimentary and E. coli dynamics in a major Mekong tributary, the Nam Khan in northern Lao PDR. Our spatial and temporal monitoring results reported seasonal variabilities of in-stream E. coli concentrations, significantly higher during the wet season, and strongly correlated to total suspended sediment (TSS) concentration, and unstocked forests percentage areas at watershed-scale. These results point out the role of TSS as an important vector for bacterial transport, as well as the importance of land use management as one of major factors affecting E. coli dissemination at watershed-scale in a tropical context prone to soil erosion. The majority of sampled tributaries had E. coli concentrations during the rainy season, exceeding 500 colonies per 100 mL, the threshold above which the WHO considers a 10% risk of gastrointestinal illness after one single exposure. The role of TSS in E. coli dynamics was further highlighted in the experimental approach, where particle-attached E. coli were predominant (91%) and showed lower decay rates as opposed to those of free-living E. coli. While deposition process was the main factor for E. coli stock reduction in the water column as opposed to solar radiation, we found that temporary resuspension of deposited sediments suggested a potential E. coli survival or even a regrowth in the sediment under tropical conditions. At last, given the importance of the hydro-sedimentary dynamics on bacterial dissemination, we assessed the dam impact reflected by abrupt decreases in terms of discharge (by an average of 42%), as well as TSS and E. coli concentrations (by an average of 89% for both) measured downstream of the dam. These statistical and modeling approaches provide new evidence of the attenuation of the bacterial contamination by the dam reservoir. Overall, this thesis work provides new insights on FIB dynamics in a tropical context that could be helpful in establishing effective strategies for water resource management

Integration of culture- and molecular-based water quality monitoring tools to protect human health

Monitoring and improving the microbiological quality and safety of surface waters used for various purposes, including drinking water abstraction and recreation is paramount as degradation may pose a serious risk to human health and cause significant economic losses as a result of the closure of beaches and shellfish harvesting areas. With the aim of providing new knowledge and tools with which to manage more effectively faecal contamination of water resources, this study focused on three goals: 1) determining the fate and suitability of new bioindicators for virus removal during wastewater treatment; 2) elucidating the levels and sources of faecal pollution in the River Tagus (Rio Tejo) using a blend of newly-developed and existing microbial source tracking (MST) markers; and 3) critically evaluating various pretreatments to distinguish between infectious and non-infectious viruses. To this end, raw and treated wastewater were collected and tested for the presence of traditional faecal indicator bacteria (FIB), and four viral bio-indicators (namely, somatic coliphages (SC), GB124 phages, human adenovirus (HAdV) and JC Polyomavirus (JCPyV)). In order to demonstrate whether the novel bio-indicators might be suitable indicators of risk to human health, Norovirus genogroup II (NoVGII) were also analysed, in parallel. FIB, SC and GB124 phages were analysed using standardised culture methods (membrane filtration and plaque assays) and HAdV, JCPyV and NoVGII were analysed using widely used molecular (qPCR) methods. Samples of river water were collected over a thirteen-month period and analysed for both non source-specific indicators of faecal contamination (Escherichia coli (EC), intestinal enterococci (IE), and SC) and source-specific contamination markers ((GB124 phages, HAdV) and four mitochondrial DNA markers (HMMit, CWMit, PigMit and PLMit)). EC, IE, SC and GB124 phages were detected by culture methods and HAdV and mitochondrial markers were detected by molecular (qPCR) methods. Furthermore, domestic animal markers (based on the detection of mitochondrial DNA) were also developed for dog and cat and tested during the catchment study. Finally, in order to determine accurately the level of risk to human health, heat-, chlorine-, and UV-inactivated Enterovirus and Mengovirus were subjected to PCR pre-treatments using enzymatic digestion and viability dyes, in order to determine infectivity. Detection of inactivated Mengovirus (MC0) was performed by RT-qPCR and detection of inactivated Enterovirus (EntV) was performed by both RT-qPCR and cell culture. The results demonstrated that the traditional bacterial indicators (FIB) were more effectively removed during wastewater treatment than GB124 phages, SC, HAdV and JCPyV, the removal levels of which were more similar to those of NoVGII. Spearman’s correlation showed that SC and GB124 phages correlated positively with NoVGII at a relatively high level and that HAdV and EC correlated positively at a moderate level. Discriminant analysis revealed that whilst no organism could predict the presence or absence of NoVGII in treated wastewater, GB124 phages in combination with other parameters did result in higher percentages of correct classification. GB124 phages plus HAdV appeared to be good candidates as alternative indicators of enteric virus removal during wastewater treatment. Results from the catchment study demonstrated that certain sites on the River Tagus are relatively highly impacted by faecal contamination (as indicated by EC, IE and SC concentrations). Moreover, the MST markers revealed that this contamination appears to be not only of human origin, but also originates from a range of other animal sources. The HMMit marker was the most prevalent and was found at the highest mean concentrations, followed by the CWMit marker. Two-way ANOVA revealed a correlation between concentrations of non source-specific indicators (and the CWMit marker) and season. Physico-chemical parameters, such as temperature and UV radiation, were found to be related to to levels of the CWMit, EC, IE, and SC. Interestingly, rainfall levels were found to be related to concentrations within the river of the PLMit marker and of the newly-developed dog and cat markers. Weak to no correlations were found between non source-specific indicators and the various MST markers, providing further evidence that these faecal indicators were unsuitable for determining the source(s) of contamination in this study. In contrast, the relatively high sensitivity and specificity of the mitochondrial DNA markers supported their use as appropriate markers of the origin of faecal contamination in this scenario. The results from the viral infectivity study demonstrated that results of ‘viability PCR’ (involving viability dyes) of chlorine- and UV-treated viruses did not correlate with those from cell culture assay. However, data from RNase-RT-qPCR from chlorine- and UV-inactivated viruses were consistent with the cell culture assay, achieving full PCR signal reduction in several instances. Heat treatment appeared to play an important role, since a significant reduction in the RT-qPCR signal was achieved. Different pre-treatments were able to achieve full removal of RT-qPCR signal for non-infectious heat-treated EntV and MC0. Therefore, enzymatic treatment may represent a rapid and inexpensive tool for discriminating between infectious and non-infectious viruses and as such should improve understanding of risks to human health. This research has demonstrated that the currently-used methodologies and approaches to assess the potential human health impact of wastewater discharges to environmental waters are limited in their ability to predict the prevalence of important agents of human waterborne disease. Furthermore, these findings provide evidence to support the development and application of alternative and potentially more effective approaches, which could better protect human health in the future

Assessing the environmental impacts of urban growth using land use/land cover, water quality and health indicators: A case study of Arequipa, Peru

Problem statement: This research assesses the direct effects of urban expansion on land cover/use, river flow, water quality and the indirect effects of these variables in the rate of gastrointestinal disease in people in Arequipa, Peru through the combined use of satellite remote sensing and geographic information systems. Approach: It also uses information about demographic changes, hydrologic data and land cover change in the Arequipa region for the last 17 years. The goal is to understand the relationship between urbanization, water quality in the Chili River and incidence of gastrointestinal diseases. Results: Landsat imagery was used to determine this relationship and to extrapolate business as usual trends into the future ten years from now. Results indicate that there has been notable urban growth and a loss in volcanic material land and cropland between 1990 and 2007, as new urban developments have appeared in these areas. The population expansion over volcanically active area is particularly troubling since it poses a potential human health risk. We also model a business as usual scenario out to the year 2020, which shows continued loss of these land use types and serves as a warning for land managers to consider alternate policies. Conclusion/Recommendations: The analysis also shows a direct correlation between urbanization with the decrease of water quality and the increase in the incidence of gastrointestinal diseases

Student Spotlight on Research and Outreach Proceedings

ESF\u27s annual Spotlight Symposium is a dynamic forum where graduate and undergraduate students share the results of their research and community service projects. The Spotlight is a student poster session highlighting scholarly efforts

Bacterial populations and human pathogens in irrigation water sources

Poor microbial water quality can cause foodborne disease from contaminated fresh produce. In Australia, regulations and certification standards lack a consistent and specific approach to defining safe water sources, making it challenging for the fresh produce industry to monitor water for human health risks. The US fresh produce industry has developed the ‘AgWater App’ to predict microbial contamination in irrigation water sources. Freshcare, Australia’s most common fresh produce safety standard, requires preharvest water to meet E. coli <100 cfu per 100mL. This thesis uses the ‘AgWater App’ approach and Freshcare criteria to determine significant correlations between physicochemical water quality and E. coli, highlighting the impact of sediment-water exchanges and environmental factors. However, site-specific influences make it challenging to design a tool that can be applied widely. The thesis also investigates the suitability of E. coli as an indicator of microbial water quality for fresh produce irrigation. Metagenomic 16S rRNA data for unculturable bacteria were used to identify food safety-related taxa present in irrigation water sources, including Bacteroides, Cyanobacteria, and Proteobacteria. Inferred functional pathways implicated in infectious diseases were also identified. Spatio-temporal trends in the data showed seasonal variation and sediment-water exchanges that impact the bacterial community dynamics. This thesis contributes to the discourse of assigning risk to irrigation water sources, providing insights into future applications of metagenomics in produce safety. The research underscores the need for evidence-based approaches to defining safe water sources and the importance of considering sediment-water exchanges and environmental factors in monitoring for human health risks. It also highlights the limitations of using E. coli as the sole indicator of food safety concerns in irrigation water sources