Diffuse Pollution Of Groundwater Research Articles

Identification and quantification of diffuse groundwater pollution in a mineralised watershed

Locating and quantifying sources of metals in a mineralised catchment, using tracer injection and synoptic sampling.

Influence of land use changes on groundwater quality – Bafoussam, West Cameroon

Abstract The purpose of this work was to show that the change in land use impacts the quality of free groundwater and therefore the health of the population in the city of Bafoussam. Land use was dominated by housing (about 42%) followed by agricultural areas (33%) and green space. The socio-economic diagnosis by the guided survey showed that 62.5% of the population consumes CAMWATER water with malaria as the dominant water-related disease. The collection of water samples analysed by the colorimetric and photometric assay has allowed us to obtain a dominant water facies of the chloride and sulphate–calcium–magnesium type. The mapping of areas potentially vulnerable to pollution by ArcGIS 10.8 software presents the low-lying areas, downstream of agricultural sites, close to industries and neighbourhoods with strong urban disorder as the most vulnerable to pollution and therefore retained as actors of diffuse groundwater pollution in the city of Bafoussam. Thus, the change in land use and the increase in agglomeration degrade the quality of groundwater in this city.

Groundwater management: Effectiveness of mitigation measures in nitrate vulnerable zones – a Portuguese case study

Groundwater vulnerability depends on hydrogeological characteristics, land use dynamics and pollutant sources. In Europe, agriculture is the main source of diffuse groundwater pollution. The over-application of nitrogen (N) soil inputs promotes nitrate leaching to surface and groundwater and associated impacts on human health and biodiversity. Mitigation programs have been implemented across the Europe Union (EU) to reduce N loads to water bodies. The EU Nitrates Directive (1991/676/EEC) aims to reduce water nitrate pollution associated to agriculture. The reduction implies the implementation of Good Agricultural Practices and National Action Programs with mandatory measures for the Nitrate Vulnerable Zones (NVZ).The Esposende-Vila do Conde is one of the nine Portuguese nitrate vulnerable zones. The application of organic and chemical fertilizers, especially on intensive agricultural farms, without the implementation of good agricultural practices and effluent management, will promote an increase in groundwater nitrate concentration. A total of 1728 groundwater sampling points were collected to determine nitrate contents, from 2007 to 2020. A space-time database including farmer questionnaires, field data and groundwater nitrate contents were prepared.The groundwater points located in artificialized territories and agricultural areas show the highest nitrate concentration. This situation is mainly due to a decrease of surface water recharge, associated to the increase of pollutant sources, as well as inadequate agricultural practices. The areas with considerable agricultural productivity and located away from surface water show an increase in nitrate concentration. The occurrence of total organic N on the soil is not an influence of groundwater nitrate contents and there is a casual relation between groundwater nitrate contents and mineral N. The methodology allows the identification of higher groundwater nitrate content, as well as pressure, state, and response indicators. However, despite the global decrease in nitrate contents, the measures remain insufficient and appropriate mitigation will be required to reduce groundwater contamination.

Institutional Issues around Agricultural Land-Use Control for Groundwater Conservation—A Long-Term Perspective

Key aspects of policy development and implementation for the control of agricultural land use to conserve groundwater are overviewed. This is one of today’s greatest environmental challenges and one on which only limited progress has been made internationally. For this purpose, the objectives of agricultural land-use control in defined areas are either to reduce diffuse pollution of groundwater and/or to regulate excessive abstraction for crop irrigation to sustain groundwater resources. Progress on both of these fronts has been assessed from the published work, and the lessons learnt are summarised for global application.

Stochastic modelling of solute mass discharge to identify potential source zones of groundwater diffuse pollution

In heavily urbanised areas, groundwater diffuse pollution is recognised as one of the most insidious threats to groundwater quality. Diffuse pollution originates from multiple small sources releasing a low contaminant mass over a relatively large area; the lack of a defined plume in groundwater, the limited leaked mass, and the fact that leakage may have occurred in the past and be now ceased, make these sources difficult to locate and characterise. In addressing this environmental issue, an inverse approach based on the Null space Monte Carlo stochastic method has been applied in the framework of an innovative methodology with the aim to locate potential source areas distributed in a large (120 km2) urban area. To simplify the problem and better understand the limitations and effectiveness of the proposed methodology, the analysis has been performed using a groundwater model with fixed (i.e., determined by a previous calibration) hydraulic conductivity and flow boundary conditions. The only source of uncertainty considered in the study is the PCE mass discharge from all model cells of the topmost layer.After implementing and calibrating a deterministic solute transport model, multiple random realisations of mass discharge fields were generated, all of which are history-match constrained and hydrogeologically plausible. The obtained stochastic parameter sets were used to investigate the statistical distribution of the solute mass discharge and map the areas that are more likely to host unknown sources of PCE. Although the application of the NSMC stochastic method on the synthetic case study has provided promising results, it has also highlighted that multiple sources of uncertainty (e.g., continuity and duration of each source, attenuation processes) could adversely affect the reliability of the results in a real-world context, in which the effect of other uncertain parameters (hydraulic conductivity amongst all) would need to be considered in addition.This study offers new insights to the problem of aquifer diffuse pollution by providing key information on the potential source zones and on the areas that urgently need to be prioritised for further investigations.

Estimation of nitrate pollution sources and transformations in groundwater of an intensive livestock-agricultural area (Comarca Lagunera), combining major ions, stable isotopes and MixSIAR model.

The identification of nitrate (NO3-) sources and biogeochemical transformations is critical for understanding the different nitrogen (N) pathways, and thus, for controlling diffuse pollution in groundwater affected by livestock and agricultural activities. This study combines chemical data, including environmental isotopes (δ2HH2O, δ18OH2O, δ15NNO3, and δ18ONO3), with land use/land cover data and a Bayesian isotope mixing model, with the aim of reducing the uncertainty when estimating the contributions of different pollution sources. Sampling was taken from 53 groundwater sites in Comarca Lagunera, northern Mexico, during 2018. The results revealed that the NO3- (as N) concentration ranged from 0.01 to 109mg/L, with more than 32% of the sites exceeding the safe limit for drinking water quality established by the World Health Organization (10mg/L). Moreover, according to the groundwater flow path, different biogeochemical transformations were observed throughout the study area: microbial nitrification was dominant in the groundwater recharge areas with elevated NO3- concentrations; in the transition zones a mixing of different transformations, such as nitrification, denitrification, and/or volatilization, were identified, associated to moderate NO3- concentrations; whereas in the discharge area the main process affecting NO3- concentrations was denitrification, resulting in low NO3- concentrations. The results of the MixSIAR isotope mixing model revealed that the application of manure from concentrated animal-feeding operations (∼48%) and urban sewage (∼43%) were the primary contributors of NO3- pollution, whereas synthetic fertilizers (∼5%), soil organic nitrogen (∼4%), and atmospheric deposition played a less important role. Finally, an estimation of an uncertainty index (UI90) of the isotope mixing results indicated that the uncertainties associated with atmospheric deposition and NO3--fertilizers were the lowest (0.05 and 0.07, respectively), while those associated with manure and sewage were the highest (0.24 and 0.20, respectively).

Groundwater diffuse pollution in functional urban areas: The need to define anthropogenic diffuse pollution background levels

Groundwater status in highly urbanized areas is particularly affected by anthropogenic influence due to diffuse pollution deriving from many sources. This makes very often challenging to determine whether the observed groundwater conditions are the result of localized pollutant sources (PS-Point Sources). In the EU legislative framework it is accepted that, when Natural Background Levels (NBLs) of undesirable elements are proven to be higher than specific Groundwater Quality Standards (GQSs), NBLs should be assumed as GQSs. No procedure is instead defined when anthropogenic Diffuse Pollution Background levels (DBPLs) are higher than GQSs and make unfeasible any remediation strategy. Among the many contaminants affecting groundwater, the chlorinated solvents, tetrachloroethylene (PCE), trichloroethylene (TCE) and trichloromethane (TCM) among the organics and hexavalent chromium, among the inorganics, having been widely used in several industries all over Europe, are very often the most prevalent contaminants in soil and groundwater. Aim of this paper is to discuss a multivariate statistical approach to address the issue of identification of anthropogenic Diffuse Pollution Background Levels. With such aim, an area of about 1600 km2, including the Functional Urban Area of Milan, was considered and 10 independent geochemical datasets, provided by local and regional agencies, and covering the period 2003–2014 were merged into a single database after homogenization and multiple quality checks. A total of 618,258 chemical analyses from 3477 sampling wells were considered, being all samples collected and analyzed through internally consistent protocols. The analysis enabled to identify five main clusters, having specific hydrogeological characteristics, different temporal profiles and pollutant background concentration levels, which were also found to respond differently to meteo-climatic changes. This study offers a robust knowledge basis for drafting a diffuse pollution management plan of the area.

An innovative method to assess suitability of Nitrate Directive measures for farm management

Controlling groundwater diffuse pollution induced by agricultural practices remains a significant challenge and has been receiving strong attention in the European Union (EU) for the last 25 years. The EU’s Nitrates Directive (91/676EC) and its associated Nitrate Vulnerable Zone (NVZ) legislation were recently revised in France in 2015, requiring farmers to adopt measures and then modify their agricultural practices to protect water resources. Yet these measures are not always implemented in an optimal way, thus limiting improvement of groundwater quality. Based on semi-directive interviews with 14 French farmers, we developed an innovative farm-scale method composed of four steps. First, we described how these farmers implemented Nitrate Directive measures. Second, we evaluated their impact on farm structure and third their consistency with farmer’s strategy. Fourth, we assessed their suitability for farm management as an integrative analysis of the previous step. Through this approach, we identified 3 types of farm management. A group of “Beyond Regulation” composed of farmers for whom Nitrate Directive measures are suitable for their farm management. They optimally implement these measures to reduce pressure on groundwater quality. For the second group named “Soft Regulation-constraints”, Nitrate Directive measures are less suitable for their farm management because they have another lucrative activity than cash crop production. This group could benefit from a redesign of the measures, changing from means- to result-oriented obligation in order to take into account the local conditions and also their farm management constraints. For the third group, denoted as “Strong Regulation-constraints”, ND measures are not suitable for their farm management. The way they implement measures is usually not optimal to reduce pressure on groundwater quality. We suggest that, investing in an “action-learning” program for such farmers could make them understand the usefulness of this regulation and help them to make the measure implementation suitable for their farm management. This farm-scale method could be used further for water management stakeholders to (i) evaluate the suitability of measures from Water Policy for the diversity of farm management or (ii) design suitable measures for the diversity of farm management on a territory subjected to groundwater pollution issue.

Statistical methods and transport modeling to assess PCE hotspots and diffuse pollution in groundwater (Milan FUA)

The Italian law 152/2006 adopted the EU Water Framework Directive principles and delegated to the Regions the task of identifying areas subject to groundwater diffuse pollution. In the Lombardy Plain, the qualitative groundwater conditions are affected mainly by the presence of industries and anthropic activities. The aim of this work was to assess tetrachloroethylene (PCE) diffuse pollution in the Milan Functional Urban Area (FUA), where chlorinated solvents are the main groundwater contaminants and the results of monitoring campaigns for the years 2003-2014 were collected in a dataset. For this purpose, a new methodology was implemented both in a deterministic and stochastic process. At first, hotspots were identified through Cluster Analysis (CA) applied to concentration values collected in unconfined/confined aquifers (2003-14). Then, a numerical transport model was implemented to study the hotspot plume extension in reason to identify monitoring wells not affected by diffuse pollution but related to specific hotspot sources. Consequently, it was possible to erase these data from the whole initial dataset in order to have a new one containing only diffuse concentrations. Interpolating them through ordinary kriging, PCE iso-concentrations maps identified areas where values are over the Maximum Contaminant Level (1.1 μg/l, Italian Law 152/06). Considering descriptive statistics and iso-PCE concentration maps, a median PCE value estimation (10 μg/l) was find as representative of PCE diffuse contamination Milan city. Moreover, a stochastic methodology was used in order to consider uncertainties due to unknown multiple-sources and environmental heterogeneity. The innovative approach gave some interesting solutions to point out areas where the contaminant mass release is higher and where high probability unknown sources can be found.

Environmental issues due to organohalogenated compounds diffuse pollution in groundwater. Emerging issue in the Roman area?

Most of the large urban areas, especially those with a strong industrial vocation, present important contamination of organohlaogenated compunds. Even in the City of Rome, although it has a very limited industrial development, some sites interested by this kind of contamination have been notified in recent years. The distribution of these sites is prevalent in the eastern sector of the city where the few industrial activities present are also located. Concentrations are varied and show both cases of clear point source contamination, where values are very high, and cases where a possible contamination from multiple point sources can be hypothesized. The sites reported fall into a crucial area for the hydrogeology of Rome, that is the "Paleotiber Graben" aquifer, exploited for various uses. To date, there is no proven diffuse contamination of organohalogenated compounds in Rome, nevertheless the purpose of this work is to frame this emerging issue on the basis of the available data.

Evaluation of the risk of diffuse pollution of groundwater by nitrogen substances from agricultural land use as background for allocation of effective measures

Abstract The risk of diffuse pollution of groundwater by nitrogen substances from agricultural land is perceived as a result of the interaction of groundwater vulnerability (determined by the characteristics of the environment overlying groundwater in relation to water transport or soil solution) and loading of overlying environment by nitrogen. Index of groundwater vulnerability was assessed on the basis of four parameters, namely, the amount of effective rainfall in the period from October to March, the capacity of soil to accumulate water, the average depth of the groundwater table and the permeability of the rock environment. Assessment of the index of loading of overlying environment by nitrogen was based on two parameters, namely, nitrogen balance and crop cover on agricultural land in the winter half on districts level in 2012, which corresponds with current state of the load. The resulting risk of groundwater pollution by nitrogen was expressed by the formula counting with the transformed values of groundwater vulnerability index and the index of loading of overlying environment by nitrogen. From practical point of view, the above mentioned indexes, as well as the subsequent risk of diffuse groundwater pollution, were spatially expressed via three associated categories. Based on the evaluation of relevant parameters, 5.18% of agricultural land falls into the category of very high and high risk, 42.20% in the medium risk category and 52.62% in the category of low and very low risk of diffuse pollution of groundwater by nitrogen from agricultural land.

Microbial Community-Level Physiological Profiles (CLPP) and herbicide mineralization potential in groundwater affected by agricultural land use

Diffuse groundwater pollution from agricultural land use may impact the microbial groundwater community, which was investigated as Community-Level Physiological Profiles (CLPP) using EcoPlate™. Water was sampled from seven piezometers and a spring in a small agricultural catchment with diffuse herbicide and nitrate pollution. Based on the Shannon–Wiener and Simpson's diversity indices the diversity in the microbial communities was high. The response from the EcoPlates™ showed which substrates support groundwater bacteria, and all 31 carbon sources were utilized by organisms from at least one water sample. However, only nine carbon sources were utilized by all water samples: d-Mannitol, N-acetyl-d-glucosamine, putrescine, d-galacturonic acid, itaconic acid, 4-hydroxy benzoic acid, tween 40, tween 80, and l-asparagine. In all water samples the microorganisms preferred d-mannitol, d-galacturonic acid, tween 40, and 4-hydroxy benzoic acid as substrates, whereas none preferred 2-hydroxy benzoic acid, α-d-lactose, d,l-α-glycerol phosphate, α-ketobutyric acid, l-threonine and glycyl-l-glutamic acid. Principal Component Analysis of the CLPP's clustered the most agriculturally affected groundwater samples, indicating that the agricultural land use affects the groundwater microbial communities. Furthermore, the ability to mineralize atrazine and isoproturon, which have been used in the catchment, was also associated with this cluster.

Groundwater Dynamics and Quality Assessment in an Agricultural Area

Problem statement: The analysis of the relationships among the different hydrogeological Units and the assessment of groundwater quality are fundamental to adopt suitable territorial planning measures aimed to reduce the potential groundwater pollution especially in agricultural regions. In this study, the characteristics of groundwater dynamics and the assessment of its quality in the Cuneo Plain (NW Italy) were examined. Approach: In order to define the geological setting an intense bibliographic analysis has been performed by the authors. This analysis was implemented by several correlated land controls and specific surveys that have permitted to analyze to certain reliability the Quaternary evolution of the entire plain sector and the current relationships among the different geological bodies that strongly affect the groundwater dynamics. Results: The Quaternary alluvial deposits overlap a Tertiary sedimentary succession through a series of erosional unconformity surfaces. These Quaternary deposits highlight a variable thickness ranging from 80-100 m in the foothills of the mountains up to a few meters in the more distal portion of the plain. In these deposits there are several unconfined aquifers which are not hydraulically interconnected due to the deep fluvial incisions that reach the underlying tertiary substrate. The Cuneo plain is intensively populated and lot of villages and farms characterize the landscape. In the overall area it is present an intensive agricultural and livestock activity predominantly represented by crops of wheat and corn and farms of cattle and pigs. All these activities represent point and diffuse groundwater pollution sources and require a considerable amount of groundwater which is withdrawn from the Quaternary aquifers by means of thousands of water wells. The groundwater quality is strongly influenced by the content of nitrates and manganese. The nitrates are linked to pollution due to agricultural activities and livestock and increase along the groundwater flow lines. The manganese content is quite high in the foothills of the mountains and in some restricted areas of the plain and appears to be linked to the natural litho logical composition of the aquifers. Conclusion: Due to high degree of intrinsic aquifers vulnerability over the entire Cuneo plain sector in order to reduce the actual groundwater pollution and the risk for human health it has to be planned several territorial suitable planning actions aimed to limit nitrates effluents and livestock untreated discharges according with the European rules.

Stochastic hydro-economic modeling for optimal management of agricultural groundwater nitrate pollution under hydraulic conductivity uncertainty

In decision-making processes, reliability and risk aversion play a decisive role. This paper presents a framework for stochastic optimization of control strategies for groundwater nitrate pollution from agriculture under hydraulic conductivity uncertainty. The main goal is to analyze the influence of uncertainty in the physical parameters of a heterogeneous groundwater diffuse pollution problem on the results of management strategies, and to introduce methods that integrate uncertainty and reliability in order to obtain strategies of spatial allocation of fertilizer use in agriculture. A hydro-economic modeling approach is used for obtaining the allocation of fertilizer reduction that complies with the maximum permissible concentration in groundwater while minimizes agricultural income losses. The model is based upon nonlinear programming and groundwater flow and mass transport numerical simulation, condensed on a pollutant concentration response matrix. The effects of the hydraulic conductivity uncertainty on the allocation of nitrogen reduction among agriculture pollution sources are analyzed using four formulations: Monte Carlo simulation with pre-assumed parameter field, Monte Carlo optimization, stacking management, and mixed-integer stochastic model with predefined reliability. The formulations were tested in an illustrative example for 100 hydraulic conductivity realizations with different variance. The results show a high probability of not meeting the groundwater quality standards when deriving a policy from just a deterministic analysis. To increase the reliability several realizations can be optimized at the same time. By using a mixed-integer stochastic formulation, the desired reliability level of the strategy can be fixed in advance. The approach allows deriving the trade-offs between the reliability of meeting the standard and the net benefits from agricultural production. In a risk-averse decision making, not only the reliability of meeting the standards counts, but also the probability distribution of the maximum pollutant concentrations. A sensitivity analysis was carried out to assess the influence of the variance of the hydraulic conductivity fields on the strategies. The results show that the larger the variance, the greater the range of maximum nitrate concentrations and the worst case (or maximum value) that could be reached for the same level of reliability.

Multivariate curve resolution of organic pollution patterns in the Ebro River surface water–groundwater–sediment–soil system

Multivariate curve resolution alternating least squares (MCR-ALS) is shown to be a powerful chemometric method for the analysis of environmental monitoring data sets. It allows for the investigation, resolution, identification, and description of pollution patterns distributed over a particular geographical area, time and environmental compartment. An integrated interpretation of the main features characterizing pollution patterns of organic contaminants affecting the Ebro River basin (Catalonia, NE Spain) is attempted using the results obtained by MCR-ALS analysis of surface water, groundwater, sediment and soil data sets obtained in a 3-year extensive monitoring study. Agricultural practices were identified as the main source of surface and groundwater diffuse pollution, while sediments and soils appeared mostly polluted by a contamination pattern mainly loaded by polycyclic aromatic hydrocarbons (PAHs) of possible pyrolitic origin. Additionally, a third pollution pattern related to past and ongoing industrial activities was detected to be principally stored in the sediment compartment. Geographical and temporal distributions of these pollution sources are given.

An approach to catchment‐scale groundwater nitrate risk assessment from diffuse agricultural sources: a case study in the Upper Bann, Northern Ireland

AbstractDRASTIC has drawbacks in groundwater risk assessment that are important in guiding activities to prevention agricultural diffuse groundwater pollution. This paper presents an improved and GIS‐based D‐DRASTIC approach for groundwater nitrate risk assessment from diffuse agricultural sources based on DRASTIC. D‐DRASTIC considers the risk concept, nitrate loading, pollutant transport with runoff, depth to water, net recharge, aquifer media, soil media, topography, impact of the vadose zone media, and the hydraulic conductivity of the aquifer. D‐DRASTIC was developed within an ArcGIS environment and applied to the Upper Bann Catchment, Northern Ireland as a case study. D‐DRASTIC shows that ‘very high’ and ‘high’ zones of groundwater nitrate risk occupy 5% and 11% of the case study area, respectively. When considering groundwater pollution sources and pathways, the results using D‐DRASTIC are helpful in guiding the activities of groundwater pollution prevention at the catchment scale in the context of better implementation of the EU Water Framework Directive. Copyright © 2008 John Wiley & Sons, Ltd.

Modelling land-use scenarios to reduce groundwater nitrate pollution: the EuropeanWater4Allproject

The Water4All project funded by the EU InterregIIIB programme aimed to demonstrate groundwater protection in the context of spatial planning and the implementation of the EU Water Framework Directive. Through a series of workshops, the four partner countries (Denmark, Germany, the Netherlands and the UK) developed a handbook containing an approach for risk-based land and water management to reduce diffuse pollution of groundwater from agricultural sources. Best practice guidelines were catalogued as a matrix of compensated and non-compensated ‘soft’ to ‘hard’ measures and were supported by illustrative case studies. The Water4All project also showed that spatially targeted measures can have wider benefits as part of a ‘whole landscape’ approach to planning and management. As an example, this paper explores a set of theoretical land-use scenarios, developed in consultation with stakeholders, which could potentially decrease nitrate concentrations in the regionally important Lincolnshire Limestone aquifer in eastern England. The results of a combined export coefficient and numerical groundwater modelling approach showed that a decrease in groundwater nitrate concentrations can be achieved over several decades with the implementation of a groundwater protection zone in which there is a significant element of land conversion from arable to woodland and grass. Hence, a long-term commitment to land management is required if the alternative and expensive end-of-pipe water treatment is to be avoided.

Assessing the cost of groundwater pollution: the case of diffuse agricultural pollution in the Upper Rhine valley aquifer

This paper presents an assessment of the costs of diffuse groundwater pollution by nitrates and pesticides for the industrial and the drinking water sectors in the Upper Rhine valley, France. Pollution costs which occurred between 1988 and 2002 are described and assessed using the avoidance cost method. Geo-statistical methods (kriging) are then used to construct three scenarios of nitrate concentration evolution. The economic consequences of each scenario are then assessed. The estimates obtained are compared with the results of a contingent valuation study carried out in the same study area ten years earlier.

Diffuse pollution threats to groundwater: a UK water company perspective

UK Water services companies have a statutory duty to supply water compliant with drinking water quality regulations. Twenty percent of Yorkshire Water9s supply is from groundwater. Deteriorating groundwater quality has resulted in closure, blending or treatment of sources. Diffuse pollutants of prime concern are Cryptosporidium , nitrate and pesticides. Risk assessments for Cryptosporidium lead to closure of spring sources and installation of membrane treatment for groundwater abstracted from a major chalk aquifer. Upward nitrate trends are observed in many aquifers; the concentration of abstracted nitrate is influenced by water-table level and pumping regimes. Government sponsored schemes to control fertilizer applications have reduced nitrate leaching from soil but not yet affected concentrations in deep well abstractions. Potential pesticide contamination from upland bracken removal has been managed by co-operative agreements with land agents. A major sandstone aquifer has been contaminated by amenity and agricultural pesticides. The implications for the water company of diffuse pollution of groundwater are long term resource reduction, less operational flexibility and increased costs. Groundwater monitoring, trend analysis and UK and international experience of cooperative agreements is discussed with reference to the requirement of the Water Framework Directive and associated Groundwater Directive for measures to protect the water environment.

A framework for monitoring regional groundwater quality

The attention currently being focused on diffuse pollution has led to an increased recognition of the role of groundwater as a pathway for transporting diffuse pollution to surface waters. Understanding and managing this issue requires a good understanding of the spatial and temporal distribution of diffuse pollution in groundwater. This in turn requires a co-ordinated approach to groundwater monitoring, to obtain accurate and representative data. This paper describes a strategic framework for groundwater quality monitoring that has recently been developed by the Environment Agency of England and Wales. The framework is implemented in three main stages: assessment of drivers and objectives, planning and implementation. The national framework is currently being implemented by a series of detailed regional programmes. These are developed on the basis of catchment-scale groundwater quality monitoring units, which will be broadly consistent with groundwater bodies defined under the European Union (EU) Water Framework Directive. The monitoring network that results from the application of the framework is designed to provide background information on groundwater quality at a catchment scale. Separate monitoring programmes will be required for monitoring pollution associated with individual sites. This paper focuses on the strategic aspects of designing a monitoring network, rather than the technical details of obtaining representative and accurate data from individual sample points, and is illustrated by a case study of the process of design of such a catchment-scale monitoring system.