DWESD - Latest Articles

Metals releases and disinfection byproduct formation in domestic wells following shock chlorination

Fri, 04 Jun 2010 00:00:00 +0200

Metals releases and disinfection byproduct formation in domestic wells following shock chlorination

Drinking Water Engineering and Science Discussions, 3, 177-198, 2010

Author(s): M. Walker and J. Newman

Shock chlorination is used for rapid disinfection to control pathogens and nuisance bacteria in domestic wells. A typical shock chlorination procedure involves adding sodium hypochlorite in liquid bleach solutions to achieve concentrations of free chlorine of up to 200 ppm in the standing water of a well. The change in pH and oxidation potential may bring trace metals from aquifer materials into solution and chlorine may react with dissolved organic carbon to form disinfection byproducts. We carried out experiments with four wells to observe and determine the persistence of increased concentrations of metals and disinfection byproducts. Water samples from shock chlorinated wells were analyzed for Pb, Cu, As, radionuclides and disinfection byproducts (haloacetic acids and trihalomethanes), immediately prior to treatment, after sufficient contact time with chlorine had elapsed, and at intervals determined by the number of casing volumes purged, for up to four times the well casing volume.

Elevated concentrations of lead and copper dissipated in proportion to free chlorine (measured semi-quantitatively) during the purging process. Trihalomethanes and haloacetic acids were formed in wells during disinfection. In one of two wells tested, disinfection byproducts dissipated in proportion to free chlorine during purging. However, one well retained disinfection byproducts and free chlorine after four well volumes had been purged. Although metals returned to background concentrations in this well, disinfection byproducts remained elevated, though below the MCL, likely because purging volume was insufficient. Simple chlorine test strips may be a useful method for indicating when purging is adequate to remove metals and disinfection by-products mobilized and formed by shock chlorination.

Understanding and managing large sensor networks

Mon, 12 Apr 2010 00:00:00 +0200

Understanding and managing large sensor networks

Drinking Water Engineering and Science Discussions, 3, 149-175, 2010

Author(s): D. D. Ediriweera and I. W. Marshall

The water supply industry is trialing a range of sensor network designs for monitoring distributed infrastructure. The paper investigates the performance of such a sensor system deployed to monitor a water distribution network. The study reveals up to one fifth of the data intended to be collected either to be missing or erroneous. Findings reinforce the importance of in-depth design consideration of all aspects of large scale sensor systems, and the necessity for expertise on every detail of the system, or access to a rule set which embeds this knowledge allowing non-specialists to make near optimal choices. First steps towards defining such a rule set is presented here with supporting evidence.

Negative pressures in full-scale distribution system: field investigation, modelling, estimation of intrusion volumes and risk for public health

Fri, 12 Mar 2010 00:00:00 +0100

Negative pressures in full-scale distribution system: field investigation, modelling, estimation of intrusion volumes and risk for public health

Drinking Water Engineering and Science Discussions, 3, 133-148, 2010

Author(s): M. C. Besner, G. Ebacher, B. S. Jung, B. Karney, J. Lavoie, P. Payment, and M. Prévost

Various investigations encompassing microbial characterization of external sources of contamination (soil and trenchwater surrounding water mains, flooded air-valve vaults), field pressure monitoring, and hydraulic and transient analyses were conducted in the same distribution system where two epidemiological studies showing an increase in gastrointestinal illness for people drinking tap water were conducted in the 1990's. Interesting results include the detection of microorganisms indicators of fecal contamination in all external sources investigated but at a higher frequency in the water from flooded air-valve vaults, and the recording of 18 negative pressure events in the distribution system during a 17-month monitoring period. Transient analysis of this large and complex distribution system was challenging and highlighted the need to consider field pressure data in the process.

Effects of ozonation and temperature on biodegradation of natural organic matter in biological granular activated carbon filters

Mon, 01 Feb 2010 00:00:00 +0100

Effects of ozonation and temperature on biodegradation of natural organic matter in biological granular activated carbon filters

Drinking Water Engineering and Science Discussions, 3, 107-132, 2010

Author(s): L. T. J. van der Aa, L. C. Rietveld, and J. C. van Dijk

Four pilot (biological) granular activated carbon ((B)GAC) filters were operated to quantify the effects of ozonation and water temperature on the biodegradation of natural organic matter (NOM) in (B)GAC filters. Removal of dissolved organic carbon (DOC), assimilable organic carbon (AOC) and oxygen and the production of carbon dioxide were taken as indicators for NOM biodegradation. Ozonation stimulated DOC and AOC removal in the BGAC filters, but had no significant effect on oxygen removal and carbon dioxide production. The temperature had no significant effect on DOC and AOC removal, while oxygen removal and carbon dioxide production increased with increasing temperature. Multivariate linear regression was used to quantify these relations. In summer the ratio between oxygen consumption and DOC removal exceeded the theoretical maximum of 2.5 g O₂·g C⁻¹ and the ratio between carbon dioxide production and DOC removal exceeded the theoretical maximum of 3.7 g CO₂·g C⁻¹. Bioregeneration of large NOM molecules could explain this excesses and the non-correlation between DOC and AOC removal and oxygen removal and carbon dioxide production. However bioregeneration of large NOM molecules was considered not likely to happen, due to sequestration.

Rapid evaluation of water supply project feasibility in Kolkata, India

Fri, 22 Jan 2010 00:00:00 +0100

Rapid evaluation of water supply project feasibility in Kolkata, India

Drinking Water Engineering and Science Discussions, 3, 65-105, 2010

Author(s): K. Dutta Roy, B. Thakur, T. S. Konar, and S. N. Chakrabarty

Mega cities in developing countries are mostly dependent on external funding for improving the civic infrastructures like water supply. International and sometimes national agencies stipulate financial justifications for infrastructure funding. Expansion of drinking water network with external funding therefore requires explicit economic estimates. A methodology suitable for local condition has been developed in this study. Relevant field data were collected for estimating the cost of supply. The artificial neural network technique has been used for cost estimate. The willingness to pay survey has been used for estimating the benefits. Cost and benefit have been compared with consideration of time value of money. The risk and uncertainty have been investigated by Monte Carlo's simulation and sensitivity analysis. The results in this case indicated that consumers were willing to pay for supply of drinking water. It has been also found that supply up to 20 km from the treatment plant is economical after which new plants should be considered. The study would help to plan for economically optimal improvement of water supply. It could be also used for estimating the water tariff structure for the city.

MUWS (Microbiology in Urban Water Systems) – an interdisciplinary approach to study microbial communities in urban water systems

Fri, 22 Jan 2010 00:00:00 +0100

MUWS (Microbiology in Urban Water Systems) – an interdisciplinary approach to study microbial communities in urban water systems

Drinking Water Engineering and Science Discussions, 3, 43-64, 2010

Author(s): P. Deines, R. Sekar, H. S. Jensen, S. Tait, J. B. Boxall, A. M. Osborn, and C. A. Biggs

Microbiology in Urban Water Systems (MUWS) is an integrated project, which aims to characterize the microorganisms found in both potable water distribution systems and sewer networks. These large infrastructure systems have a major impact on our quality of life, and despite the importance of these systems as major components of the water cycle, little is known about their microbial ecology. Potable water distribution systems are large, highly interconnected and dynamic, and difficult to control. Sewer systems are also large and subject to time varying inputs and demands. Their performance also faces increasing loading due to increasing urbanization and longer-term environmental changes. Therefore, understanding the link between microbial ecology and any potential impacts on short or long-term engineering performance is important. By combining the strengths and research expertise of civil-, biochemical engineers and molecular microbial ecologists, we aim to link the abundance and diversity of microorganisms to physical and engineering variables so that novel insights into the ecology of microorganisms within both water distribution systems and sewer networks can be explored. By presenting the details of this multidisciplinary approach, and the principals behind the molecular microbiological methods and techniques that we use, this paper will demonstrate the potential of an integrated approach to better understand urban water system function and so meet future challenges.

I-WARP: individual water main renewal planner

Wed, 13 Jan 2010 00:00:00 +0100

I-WARP: individual water main renewal planner

Drinking Water Engineering and Science Discussions, 3, 25-41, 2010

Author(s): Y. Kleiner and B. Rajani

I-WARP is based upon a nonhomogeneous Poisson approach to model breakage rates in individual water mains. The structural deterioration of water mains and their subsequent failure are affected by many factors, both static (e.g., pipe material, pipe size, age (vintage), soil type) and dynamic (e.g., climate, cathodic protection, pressure zone changes). I-WARP allows for the consideration of both static and dynamic factors in the statistical analysis of historical breakage patterns. This paper describes the mathematical approach and demonstrates its application with the help of a case study. The research project within which I-WARP was developed, was jointly funded by the National Research Council of Canada (NRC), and the Water Research foundation (formerly known as the American Water Works Association Research Foundation – AwwaRF) and supported by water utilities from USA and Canada.

A bottom-up approach of stochastic demand allocation in water quality modelling

Mon, 04 Jan 2010 00:00:00 +0100

A bottom-up approach of stochastic demand allocation in water quality modelling

Drinking Water Engineering and Science Discussions, 3, 1-24, 2010

Author(s): E. J. M. Blokker, J. H. G. Vreeburg, H. Beverloo, M. Klein Arfman, and J. C. van Dijk

An "all pipes" hydraulic model of a DMA-sized drinking water distribution system was constructed with two types of demand allocations. One is constructed with the conventional top-down approach, i.e. a demand multiplier pattern from the booster station is allocated to all demand nodes with a correction factor to account for the average water demand on that node. The other is constructed with a bottom-up approach of demand allocation, i.e., each individual home is represented by one demand node with its own stochastic water demand pattern.

The stochastic water demand patterns are constructed with an end-use model on a per second basis and per individual home. The flow entering the test area was measured and a tracer test with sodium chloride was performed to measure travel times. The two models were evaluated on the predicted sum of demands and travel times, compared with what was measured in the test area.

The new bottom-up approach performs at least as well as the conventional top-down approach with respect to total demand and travel times, without the need for any flow measurements or calibration measurements. The bottom-up approach leads to a stochastic method of hydraulic modelling and gives insight into the variability of travel times as an added feature beyond the conventional way of modelling.

Online modelling of water distribution systems: a UK case study

Wed, 23 Dec 2009 00:00:00 +0100

Online modelling of water distribution systems: a UK case study

Drinking Water Engineering and Science Discussions, 2, 279-294, 2009

Author(s): J. Machell, S. R. Mounce, and J. B. Boxall

Hydraulic simulation models of water distribution networks are routinely used for operational investigations and network design purposes. However, their full potential is often never realised because, in the majority of cases, they have been calibrated with data collected manually from the field during a single historic time period and, as such, reflect the network operational conditions that were prevalent at that time, and they are then applied as part of a reactive, desktop investigation. In order to use a hydraulic model to assist proactive distribution network management its element asset information must be up to date and it should be able to access current network information to drive simulations. Historically this advance has been restricted by the high cost of collecting and transferring the necessary field measurements. However, recent innovation and cost reductions associated with data transfer is resulting in collection of data from increasing numbers of sensors in water supply systems, and automatic transfer of the data to point of use. This means engineers potentially have access to a constant stream of current network data that enables a new era of "online" modelling that can be used to continually assess standards of service compliance for pressure and reduce the impact of network events, such as mains bursts, on customers. A case study is presented here that shows how an online modelling system can give timely warning of changes from normal network operation, providing capacity to minimise customer impact.

Fluorescence spectroscopy as a tool for determination of organic matter removal efficiency at water treatment works

Wed, 23 Dec 2009 00:00:00 +0100

Fluorescence spectroscopy as a tool for determination of organic matter removal efficiency at water treatment works

Drinking Water Engineering and Science Discussions, 2, 259-278, 2009

Author(s): M. Z. Bieroza, J. Bridgeman, and A. Baker

Organic matter (OM) in drinking water treatment is a common impediment responsible for increased coagulant and disinfectant dosages, formation of carcinogenic disinfection-by products, and microbial re-growth in distribution system. The inherent heterogeneity of OM implies the utilization of advanced analytical techniques for its characterization and assessment of removal efficiency. Here, the application of simple fluorescence excitation-emission technique to OM characterization in drinking water treatment is presented. The fluorescence data of raw and clarified water was obtained from 16 drinking water treatment works. The reduction in fulvic-like fluorescence was found to significantly correlate with OM removal measured with total organic carbon (TOC). Fluorescence properties, fulvic- and tryptophan-like regions, were found to discriminate OM fractions of different removal efficiencies.

The results obtained in the study show that fluorescence spectroscopy provides a rapid and accurate characterization and quantification of OM fractions and indication of their treatability in conventional water treatment.

NOM characterization and removal at six Southern African water treatment plants

Tue, 10 Nov 2009 00:00:00 +0100

NOM characterization and removal at six Southern African water treatment plants

Drinking Water Engineering and Science Discussions, 2, 231-257, 2009

Author(s): J. Haarhoff, M. Kubare, B. Mamba, R. Krause, T. Nkambule, B. Matsebula, and J. Menge

Organic pollution is a major concern during drinking water treatment. Major challenges attributed to organic pollution include the proliferation of pathogenic micro-organisms, prevalence of toxic and physiologically disruptive organic micropollutants, and quality deterioration in water distribution systems. A major component of organic pollution is natural organic matter (NOM). The operational mechanisms of most unit processes are well understood. However, their interaction with NOM is still the subject of scientific research. This paper takes the form of a metastudy to capture some of the experiences with NOM monitoring and analysis at a number of Southern African Water Treatment Plants. It is written from the perspective of practical process selection, to try and coax some pointers from the available data for the design of more detailed pilot work. NOM was tracked at six water treatment plants using dissolved organic carbon (DOC) measurements. Fractionation of the DOC based on biodegradability and molecular weight distribution was done at a water treatment plant in Namibia. A third fractionation technique using ion exchange resins was used to assess the impact of ozonation on DOC. DOC measurements alone did not give much insight into NOM evolution through the treatment train. The more detailed characterization techniques showed that different unit processes preferentially remove different NOM fractions. Therefore these techniques provide better information for process design and optimisation than the DOC measurement which is routinely done during full scale operation at these water treatment plants. Further work will focus on streamlining and improving the reproducibility of selected fractionation techniques, characterization of NOM from different water sources, and synthesis of the results into a systematic, practical guideline for process design and optimisation.

Optimized conditions for application of organic flocculant aids in water purification

Tue, 03 Nov 2009 00:00:00 +0100

Optimized conditions for application of organic flocculant aids in water purification

Drinking Water Engineering and Science Discussions, 2, 205-229, 2009

Author(s): P. Polasek

The application of organic flocculant aid (OFA) to a system undergoing aggregation has a direct effect on the quality of purified water as well as the settleability of resultant agglomerates. The optimum conditions for OFA application exist when the formation of aggregates by means of destabilisation (aggregation – CPE) reagent reaches flocculation optimum, i.e. the measure of flocculation γ=1, prior to OFA addition. Such method of OFA application is called the Post-Orthokinetic Agglomeration (POA) process. The POA process results in the formation of the fastest settleable agglomerates and the best quality of purified water matching that attainable without the use of OFA. Recirculation of the sludge conditioned by OFA back to the process of particle aggregation was found undesirable as it adversely affects the purified water quality as well as the settleability of produced agglomerates.

Development of a predictive model to determine micropollutant removal using granular activated carbon

Tue, 13 Oct 2009 00:00:00 +0200

Development of a predictive model to determine micropollutant removal using granular activated carbon

Drinking Water Engineering and Science Discussions, 2, 189-204, 2009

Author(s): D. J. de Ridder, M. McConville, A. R. D. Verliefde, L. T. J. van der Aa, S. G. J. Heijman, J. Q. J. C. Verberk, L. C. Rietveld, and J. C. van Dijk

The occurrence of organic micropollutants in drinking water and its sources has opened up a field of study related to monitoring concentration levels in water sources, evaluating their toxicity and estimating their removal in drinking water treatment processes. Because a large number of organic micropollutants is currently present (although in relatively low concentrations) in drinking water sources, a method should be developed to select which micropollutants has to be evaluated with priority. In this paper, a screening model is presented that can predict solute removal by activated carbon, in ultrapure water and in natural water. Solute removal prediction is based on a combination of solute hydrophobicity (expressed as log D, the pH corrected log K_ow), solute charge and the carbon dose. Solute molecular weight was also considered as model input parameter, but this solute property appeared to relate insufficiently to solute removal.

Removal of negatively charged solutes by preloaded activated carbon was reduced while the removal of positively charged solutes was increased, compared with freshly regenerated activated carbon. Differences in charged solute removal by freshly regenerated activated carbon were small, indicating that charge interactions are an important mechanism in adsorption onto preloaded carbon. The predicted solute removal was within 20 removal-% deviation of experimentally measured values.

NOM removal technologies – Norwegian experiences

Fri, 09 Oct 2009 00:00:00 +0200

NOM removal technologies – Norwegian experiences

Drinking Water Engineering and Science Discussions, 2, 161-187, 2009

Author(s): H. Ødegaard, S. Østerhus, E. Melin, and B. Eikebrokk

The paper gives an overview of the methods for removal of natural organic matter (NOM), particularly humic substances (HS), in water with focus on the Norwegian experiences. It is demonstrated that humic substances may be removed by a variety of methods, such as; molecular sieving through nanofiltration membranes, coagulation with subsequent floc separation (including granular media or membrane filtration), oxidation followed by biofiltration and sorption processes including chemisorption (ion exchange) and physical adsorption (activated carbon). All these processes are in use in Norway and the paper gives an overview of the operational experiences.

Water quality and treatment of river bank filtrate

Tue, 06 Oct 2009 00:00:00 +0200

Water quality and treatment of river bank filtrate

Drinking Water Engineering and Science Discussions, 2, 127-159, 2009

Author(s): W. W. J. M. de Vet, C. C. A. van Genuchten, M. C. M. van Loosdrecht, and J. C. van Dijk

In drinking water production, river bank filtration has the advantages of dampening peak concentrations of many dissolved components, substantially removing many micropollutants and removing, virtually completely, the pathogens and suspended solids. The production aquifer is not only fed by the river bank infiltrate but also by water percolating through covering layers. In the polder areas, these top layers consist of peat and deposits from river sediments and sea intrusions.

This paper discusses the origin and fate of macro pollutants in river bank filtrate, based on extensive full-scale measurements in well fields and treatment systems of the Drinking Water Company Oasen in the Netherlands. First, it clarifies and illustrates redox reactions and the mixing of river bank filtrate and polder water as the dominant processes determining the raw water quality for drinking water production. Next, full-scale results are elaborated on to evaluate trickling filtration as an efficient and proven one-step process to remove methane, iron, ammonium and manganese. The interaction of methane and manganese removal with nitrification in these systems is further analyzed. Methane is mostly stripped during trickling filtration and its removal hardly interferes with nitrification. Under specific conditions, microbial manganese removal may play a dominant role.

Impact of decreasing water demand on bank filtration in Saxony, Germany

Thu, 27 Aug 2009 00:00:00 +0200

Impact of decreasing water demand on bank filtration in Saxony, Germany

Drinking Water Engineering and Science Discussions, 2, 101-126, 2009

Author(s): T. Grischek, D. Schoenheinz, C. Syhre, and K. Saupe

Bank filtration has been of main importance for the drinking water supply in Germany for many decades. The water quality of pumped raw water from bank filtration sites depends to a high degree on the water quality of the infiltrating surface water and the landside groundwater, the mixing portion of both as well as the flow and transport conditions in the aquifer. Since the improvement of river water quality and a drastic decrease in water demand during the last 15 years in Germany, the influence of landside groundwater quality has become more important for the raw water quality of waterworks relying on bank filtration. The hydrogeologic analysis of three bank filtration sites in Saxony and the management of abstraction rates and well operation in response to fluctuating water demand are discussed. In conclusion, a general overview on management options for bank filtration sites is provided.

Removal of radio N-nitrosodimethylamine (NDMA) from drinking water by coagulation and Powdered Activated Carbon (PAC) adsorption

Tue, 31 Mar 2009 00:00:00 +0200

Removal of radio N-nitrosodimethylamine (NDMA) from drinking water by coagulation and Powdered Activated Carbon (PAC) adsorption

Drinking Water Engineering and Science Discussions, 2, 79-100, 2009

Author(s): J. Chung, Y. Yoon, M. Kim, S.-B. Lee, H.-J. Kim, and C.-K. Choi

The presence of N-nitrosodimethylamine (NDMA) in drinking water supplies has raised concern over its removal by common drinking water treatment processes. A simple detection method based on scintillation spectroscopy has been used to quantify the concentration of ¹⁴C-labeled NDMA at various ratios of sample to scintillation liquid. Without sample pretreatment, the method detection limits are 0.91, 0.98, 1.23, and 1.45 ng/L of NDMA at scintillation intensity ratios of 10:10, 5:15, 15:5, and 2.5:17.5 (sample: scintillation liquid), respectively. The scintillation intensity in all cases is linear (R²>0.99) and is in the range of 0 to 100 ng/L of NDMA. In addition, because scintillation intensity is independent of solution pH, conductivity, and background electrolyte ion types, a separate calibration curve is unnecessary for NDMA samples at different solution conditions. Bench-scale experiments were performed to simulate individual treatment processes, which include coagulation and adsorption by powdered activated carbon (PAC), as used in a drinking water treatment plant, and biosorption, a technique used in biological treatment of waste water. The commonly used coagulation process for particulate control and biosorption is ineffective for removing NDMA (<10% by coagulation and <20% by biosorption). However, high doses of PAC may be applied to remove NDMA.

Technical Note: Community of bacteria attached on the PVDF MF membrane surface fouled from drinking water treatment, in Seoul, Korea

Mon, 02 Mar 2009 00:00:00 +0100

Technical Note: Community of bacteria attached on the PVDF MF membrane surface fouled from drinking water treatment, in Seoul, Korea

Drinking Water Engineering and Science Discussions, 2, 65-77, 2009

Author(s): Kyongmi Chon, Kangmin Chon, Jin-Soo Chang, Heekyong Oh, Euisin Lee, and Jaeweon Cho

Alpha, beta, and gamma proteobacteria comprise approximate 68, 16, and 7% of all identified bacteria. In this study, bacterial communities that had fouled polyvinylidene fluoride microfiltration membranes, which are used for drinking water treatment, over an 18 month period were analyzed using the 16s rRNA gene clone library method. The alpha, beta, and gamma proteobacteria were composed of mainly Bradyrhizobium and Rhodopseudomonas, Ralstonia, and Legionella, respectively. The presence of a relatively high amount of alpha proteobacteria was due to the oligotrophic condition of the drinking water source, the Han River, tested in this specific case study. The second most prominent bacteria community was the beta proteobacteria, which are typically found in a freshwater environment. This finding supports the notion that the drinking water source was relatively clean. Analyses of the organic foulants indicated that the they were most likely from extra cellular polymers and/or cell fractured chemicals from bacteria or micro-organisms, as identified using organic characterizing tools, including 3 dimensional fluorescence excitation-emission matrix and Fourier transform IR analyses.

Arsenic in drinking water: not just a problem for Bangladesh

Thu, 26 Feb 2009 00:00:00 +0100

Arsenic in drinking water: not just a problem for Bangladesh

Drinking Water Engineering and Science Discussions, 2, 51-64, 2009

Author(s): D. van Halem, S. A. Bakker, G. L. Amy, and J. C. van Dijk

For more than a decade it has been known that shallow tube wells in Bangladesh are frequently contaminated with arsenic concentrations at a level that is harmful to human health. By now it is becoming clear that a disaster of an unheard magnitude is going on: the World Health Organization fears that in the near future 1 in every 10 adult deaths in Bangladesh will be caused by arsenic-related cancers. Other studies show that problems with arsenic in groundwater/drinking water occur in many more countries worldwide, such as in the USA and China. In Europe the focus on arsenic problems is confined to countries with high arsenic levels in their groundwater, such as Romania, Hungary and Italy. In most other European countries, the naturally occurring arsenic concentrations are lower than the drinking water standard of 10 μg L⁻¹. However, from the literature review presented in this paper, it may also be concluded that using the European standard, health risks cannot be excluded. It is therefore recommended that the current arsenic standard be reconsidered.

Spatial and temporal variability of heavy metals in streams of the Flint Creek and Flint River Watersheds from non-point sources

Mon, 23 Feb 2009 00:00:00 +0100

Spatial and temporal variability of heavy metals in streams of the Flint Creek and Flint River Watersheds from non-point sources

Drinking Water Engineering and Science Discussions, 2, 25-49, 2009

Author(s): I. Abdi, T. Tsegaye, M. Silitonga, and W. Tadesse

Throughout the United States, non-point pollution is responsible for large quantities of heavy metals entering bodies of water. Pollution as a result of heavy metals can impact drinking water supplies, recreation, fisheries, and aquatic species. Presence of heavy metals such as lead (Pb), cadmium (Cd), and chromium (Cr), in surface water may pose great risks to human health as well as to aquatic animals. In order to understand water quality changes due to heavy metal elements and pH as a result of spatial and temporal variability and land use/land cover changes, there is a need to monitor water bodies on a constant basis. The purpose of this investigation was to assess the impacts of spatial and temporal variability on heavy metals and pH as a result of land use/land cover changes and provide a baseline for future water quality study from non-point sources in two watersheds. Spatial and temporal variability factors were not significant for all the heavy metal elements. Significant water quality changes occurred between 2003 and 2004 for the two of the five heavy metals (Pb, and Ni) and pH. However, this was not true for the other of heavy metals investigated (Cd, Cr, and Zn). There was no influence of watershed observed for any of the heavy metals and pH in this study. To accurately quantify environmental impacts of heavy metals as well as pH, land use changes, and natural processes leading to spatial and temporal variability of water quality variables, continuous monitoring of surface water is necessary to improve the water quality of these watersheds.