CONSOLIDATION OF A STREAM QUALITY MONITORING NETWORK1

ABSTRACT A method for systematic consolidation of a fixed station water quality monitoring network using dynamic programming is described. The approach utilizes a hierarchical structure; stations are allocated to what are termed primary basins on the basis of a weighted attribute score, and specific station locations within each primary basin are specified using a criterion based on stream order numbers. The method has been applied to the Municipality of Metropolitan Seattle (Metro) stream and river quality monitoring network. The results aided in a 1982 metro decision to reduce the scope of its fixed station monitoring from 81 to 47 stations, at an annual savings of approximately $33,000 per year exclusive of equipment depreciation and indirect costs.     

NEW ZEALAND'S NATIONAL WATER QUALITY MONITORING NETWORK - DESIGN AND FIRST YEAR'S OPERATION1

ABSTRACT: The design and implementation of a national surface water quality monitoring network for New Zealand are described. Some of the lessons learned from the first year of operation are also addressed. Underpinning the design, and specified in advance, are the goal and objectives, the data quality assurance system, and the mechanism for data interpretation and reporting. Because of the difficulties associated with the use of a multitude of different agencies, only one agency is involved in field work and one laboratory undertakes the analysis. Staff training has been given a high priority. The network has been designed to give good trend detectability for regular sampling over a 5–10 year period.     

GROUND WATER MONITORING NETWORK DESIGN USING MULTIPLE CRITERIA DECISION MAKING ANT) GEOSTATISTICS1

ABSTRACT: A multi-criteria approach to ground water quality monitoring network design is developed. The methodology combines multi-criteria decision making (MCDM) and modifications of geostatistical variance reduction analysis. Composite programming, a distance based optimization algorithm that employs a hierarchial structure, is used for the MCDM component of the design methodology. MCDM allows the consideration of numerous, often conflicting, design criteria. The methodology is useful for identifying the preferred combination of direct borehole and indirect geo-electric data. It also permits the use of prior information during initial stages of network development. Multi-variate kriging is employed to evaluate network performance using the combination of direct borehole data and indirect geoelectric data. Weighted measures of estimation variance are used as primary measures of performance, with the reduction in estimation variance being computed by the fictitious point method. Case study results demonstrate that the network design methodology can be used in both early and late phases of network development. It also leads to selection of the preferred combination and spatial orientation of direct and indirect data sources while considering cost-effectiveness and performance of alternative designs.     

DESIGN CONSIDERATIONS FOR AMBIENT STREAM QUALITY MONITORING1

ABSTRACT: Existing ambient water quality monitoring programs have resulted in data which are often unsuitable for assessment of water quality trends. A primary concern in designing a stream quality monitoring network is the selection of a temporal sampling strategy. It is extremely important that data for trend assessment be collected uniformly in time. Greatly superior trend detection power results for such a strategy as compared to stratified sampling strategies. In general, it is desirable that sampling frequencies be at least monthly but not greater than biweekly; higher sampling frequencies usually result in little additional information. An upper limit on trend detectability exists such that for both five and ten year base periods it is often impossible to detect trends in time series where the ratio of the trend magnitude to time series standard deviation is less than about 0.5. For the same record lengths trends in records with trend to standard deviation ratios greater than about one can usually be detected with very high power when a uniform sampling strategy is followed.     

AN EMPIRICALLY‐BASED SEQUENTIAL GROUND WATER MONITORING NETWORK DESIGN PROCEDURE1

ABSTRACT: A procedure using a simple, empirically‐based model that makes efficient use of available information has been developed for designing a ground water monitoring well network. A moving plume is described by siting wells in a sequential manner, relying upon two‐dimensional concentration data obtained from previously installed wells to determine the locations of future wells. Data sets from two well known, densely monitored natural gradient tracer studies were used to test the procedure. Plumes defined by all information in the original networks were compared to those defined by reduced networks designed by the new procedure. The new procedure tracked the plumes using only a portion of that information. The new procedure could have reduced the number of wells in the original tests by about 50 percent without appreciable loss of plume information as measured by plume location and extent and by tracer mass.     

DESIGN AND IMPLEMENTATION OF A COOPERATIVE WATER QUALITY MONITORING PROGRAM IN COLORADO'S BIG THOMPSON WATERSHED1

ABSTRACT: In 1996, the Big Thompson Watershed Forum (BTWF) was formed “to assess and protect the quality of water” in the Big Thompson Watershed in northern Colorado. However, until 1999, water quality monitoring in the watershed was performed by many state, local, and federal agencies with no coordination among programs and with few efforts toward efficiency, data comparability, or information exchange. To better meet the needs of its stakeholders, the BTWF since 1999 has been actively pursuing the design and implementation of a cooperative water quality monitoring program. The program design involved consensus building among the funding participants, primarily drinking water providers. The final design included 38 parameters to be sampled 15 times per year at 24 stream and canal locations plus two reservoirs. Although the collaborative consensus based approach has been successful for the BTWF, this approach has its drawbacks; most notable among these are the time and labor this approach requires. Also, the BTWF struggled with achieving equal representation of all interests, since those agencies that provided funding had the greatest voice in the final product. While a collaborative approach may not always be best for monitoring program design, it should be appropriate for many watershed organizations that face the common problem of severe financial constraints.     

WATER QUALITY MONITORING: WHERE'S THE BEEF?1

ABSTRACT: Water quality monitoring, as a function of society's efforts to manage the environment, is the contact mechanism that management and the public has with the actual water quality in the environment. Water quality monitoring has been studied extensively for many years to ensure that it produces information about water quality conditions. Current efforts to reduce government spending will have negative impacts on those government functions deemed to be non-responsive to the needs of the public. How well does water quality monitoring inform taxpayers about the status and trends in water quality conditions in the United States? This paper reviews a number of past efforts to “improve” water quality monitoring, discusses barriers to such improvement, and suggests ways that monitoring can be made more accountable for the information it should be producing for public understanding of water quality conditions. In particular, the need for standardization in data analysis and reporting of information to the public, is highlighted.     

APPLICATION OF GEOGRAPHIC INFORMATION SYSTEMS TO GROUNDWATER MONITORING NETWORK DESIGN1

ABSTRACT: Effective monitoring configurations for contaminant detection in groundwater can be designed by analyzing the spatial relationships between candidate sampling sites and aquifer zones susceptible to contamination. Examples of such zones are the domain underlying the contaminant source, zones of probable contaminant migration, and areas occupied by water supply wells. Geographic information systems (GIS) are well-suited to performing key groundwater monitoring network design tasks, such as calculating values for distance variables which quantify the proximity of candidate sites to zones of high pollution susceptibility, and utilizing these variables to quantify relative monitoring value throughout a model domain. Through a case study application, this paper outlines the utility of GIS for detection-based groundwater quality monitoring network design. The results suggest that GIS capabilities for analyzing spatially referenced data can enhance the field-applicability of established methodologies for groundwater monitoring network design.     

REGULATORY WATER QUALITY MONITORING: A SYSTEMS PERSPECTIVE1

ABSTRACT: Regulatory water quality monitoring has evolved to the point where it is a rather complex system encompassing many monitoring purposes and involving many monitoring activities. Lack of a system's perspective of regulatory monitoring hinders the development of effective and efficient monitoring programs to support water quality management. In this paper the regulatory water quality monitoring system is examined in a total systems context. The purposes of regulatory monitoring are reviewed and categorized according to their legal evolution. The activities of regulatory monitoring are categorized and organized into a system which follows the flow of information through the monitoring program. The monitoring purposes and activities are combined to form a monitoring system matrix - a framework within which the total regulatory water quality monitoring system is defined. The matrix, by defining the regulatory monitoring system and clarifying many interactions within the system, provides a basis upon which a more thorough approach to managing, evaluating, and eventually optimizing regulatory monitoring can be developed.     

ESTABLISHING STATISTICAL DESIGN CRITERIA FOR WATER QUALITY MONITORING SYSTEMS: REVIEW AND SYNTHESIS1

ABSTRACT: Regulatory water quality management has placed fairly extensive information expectations on routine, fixed-station monitoring without a corresponding emphasis being placed on the need to design monitoring systems to meet these expectations. To correct the situation there is increasing interest in developing more quantitative monitoring system design procedures which incorporate the statistical nature of sampling. In examining the development of such quantitative criteria, this paper describes the roles of statistics in a systematic approach to monitoring - initial design and routine reporting of results - and reviews the use of statistics in each. The paper emphasizes the need to tie the two together, via statistical design criteria, in order for the identified information expectations to be met in a statistically sound manner. However, the use of statistics in water quality monitoring is noted as currently being as much an art as it is a science.     

SAMPLING FREQUENCY SELECTION FOR REGULATORY WATER QUALITY MONITORING1

ABSTRACT: The selection of sampling frequencies in order to achieve reasonably small and uniform confidence interval widths about annual sample means or sample geometric means of water quality constituents is suggested as a rational approach to regulatory monitoring network design. Methods are presented for predicting confidence interval widths at specified sampling frequencies while considering both seasonal variation and serial correlation of the quality time series. Deterministic annual cycles are isolated and serial dependence structures of the autoregressive, moving average type are identified through time series analysis of historic water quality records. The methods are applied to records for five quality constituents from a nine-station network in Illinois. Confidence interval widths about annual geometric means are computed over a range of sampling frequencies appropriate in regulatory monitoring. Results are compared with those obtained when a less rigorous approach, ignoring seasonal variation and serial correlation, is used. For a monthly sampling frequency the error created by ignoring both seasonal variation and serial correlation is approximately 8 percent. Finally, a simpler technique for evaluating serial correlation effects based on the assumption of AR(1) type dependence is examined. It is suggested that values of the parameter p₁, in the AR(1) model should range from 0.75 to 0.90 for the constituents and region studied.     

DESIGN OF AN INDEX OF WATER QUALITY1

ABSTRACT: This paper describes the formulation of an Index of Water Quality to evaluate the level of pollution in fresh water. A Four-Round Delphi equation, using a panel of seven nationally recognized water scientists, was performed to ascertain the pollutants to be included in the index, the relationship between the quantity of these pollutants in the water and the resulting quality of the water, and the importance of each pollution variable to each water use as well as to overall pollution. A multiplicative index was used to bring the pollutants together into one system.     

SCREENING THE RELOCATION STRATEGIES OF WATER QUALITY MONITORING STATIONS BY COMPROMISE PROGRAMMING1

Water quality monitoring network designs historically have tended to use experience, intuition, and subjective judgment in siting monitoring stations only sporadically. Better design procedures for optimizing monitoring systems with respect to multiple criteria decision analysis had rarely been put into practice up front when the needs for intensive monitoring became critical. This paper describes a systematic relocation strategy that is organized to identify several significant planning objectives and consider a series of inherent constraints simultaneously. The planning objectives considered in this analysis are designed to enhance the detection possibility for lower compliance areas, reflect the emphasis for different attainable water uses at different locations, promote the potential detection for the lower degradation areas of pollutants, increase the protection degree of those areas with higher population density in the proximity of the river system, and strengthen the pre‐warning capability of water quality for water intakes. The constraint set contains the limitations of budget, the equity implication, and the detection sensitivity in the water environment. A case study in the Kao‐Ping River Basin, South Taiwan, demonstrates the application potential of this methodology based on a seamless integration between the optimization and the simulation models. It enables identification of the optimal locational pattern stepwise using the embedded screening and sequencing capacity in a compromise programming model. However, a well calibrated and verified water quality model is an indispensable tool in support of this multiobjective evaluation. Extra sampling procedures become necessary for the sites with sparse environmental information. Comparison of planning outcomes of compromise programming is made against previously achieved analyses by using weighted programming and fuzzy programming.     

CONSIDERATIONS OF SCALE IN WATER QUALITY MONITORING AND DATA ANALYSIS1

ABSTRACT: An assumption of scale is inherent in any environmental monitoring exercise. The temporal or spatial scale of interest defines the statistical model which would be most appropriate for a given system and thus affects both sampling design and data analysis. Two monitoring objectives which are strongly tied to scale are the estimation of average conditions and the evaluation of trends. For both of these objectives, the time or spatial scale of interest strongly influences whether a given set of observations should be regarded as independent or serially correlated and affects the importance of serial correlation in choosing statistical methods. In particular serial correlation has a much different effect on the estimation of long-term means than it does on the estimation of specific-period means. For estimating trends, a distinction between serial correlation and trend is scale dependent. An explicit consideration of scale in monitoring system design and data analysis is, therefore, most important for producing meaningful statistical information.     

MONITORING STRATEGIES TO DETERMINE COMPLIANCE WITH WATER QUALITY OBJIECTIVES1

ABSTRACT: Two sampling strategies designed to test for compliance with water quality objectives are examined. For objectives based on long-term mean requirements, fixed frequency sampling at frequent intervals is most advantageous regardless of the underlying distribution of the data. For objectives that are based on maximum allowable concentrations, effective sampling strategies increase the likelihood of detecting noncompliance. If data are highly autocorrelated or sharply seasonal in distribution, an exceedance-driven sampling strategy is more effective and efficient for detecting violations than fixed frequency sampling. However, data generated by exceedance-driven sampling provide biased estimates of mean and standard deviation.     

A DECISION SUPPORT SYSTEM FOR WATER QUALITY DATA AUGMENTATION: A CASE STUDY1

ABSTRACT: Recent developments in water quality monitoring have generated interest in combining non-probability and probability data to improve water quality assessment. The Interagency Task Force on Water Quality Monitoring has taken the lead in exploring data combination possibilities. In this paper we take a developed statistical algorithm for combining the two data types and present an efficient process for implementing the desired data augmentation. In a case study simulated Environmental Protection Agency (EPA) Environmental Monitoring and Assessment Program (EMAP) probability data are combined with auxiliary monitoring station data. Auxiliary stations were identified on the STORET water quality database. The sampling frame is constructed using ARC/INFO and EPA's Reach File-3 (RF3) hydrography data. The procedures for locating auxiliary stations, constructing an EMAP-SWS sampling frame, simulating pollutant exposure, and combining EMAP and auxiliary stations were developed as a decision support system (DSS). In the case study with EMAP, the DSS was used to quantify the expected increases in estimate precision. The benefit of using auxiliary stations in EMAP estimates was measured as the decrease in standard error of the estimate.     

RESERVOIR WATER QUALITY SAMPLING DESIGN1

ABSTRACT: The design of monitoring programs often serves as one of the major sources of error or uncertainty in water quality data. Properly designed programs should minimize uncertainty or at least provide a means by which variability can be partitioned into recognizable components. While the design of sampling programs has received recent attention, commonly employed strategies for limnological sampling of lakes may not be completely appropriate for many reservoirs. Based on NES data, reservoirs are generally larger, deeper, and morphologically more complex than natural lakes. Reservoirs also receive a majority of their inflow from a single tributary located a considerable distance from the point of outflow. The result is the establishment of marked physical, biological, and chemical gradients from headwater to dam. The existence of horizontal as well as vertical gradients, and their importance in water quality sampling design were the subject of intensive transect sampling efforts at DeGray Lake, a U.S. Army Corps of Engineers reservoir in southern Arkansas. Data collected were used to partition Variance, identify areas of similarity, and demonstrate how an equitable sampling program might be designed.     

A PRACTICAL MODEL INTEGRATING QUALITY ASSURANCE INTO ENVIRONMENTAL MONITORING1

ABSTRACT: A model of comprehensive environmental monitoring process with integral quality assurance is presented. This model views the monitoring process as iterative cycles of a series of elements: design, plan, protocols, preparation, field liaison, sample collection, sample handling, laboratory analysis, data transmission, data validation, data approval, data provision, statistical analysis, and reporting. Quality assurance is linked to each element, not just to laboratory analysis. The program of quality assurance ensures that environmental monitoring data are compatible with the project goals, are comparable between various sampling agencies, and maintain a high degree of scientific credibility. The key characteristics of the overall quality assurance process are detailed documentation, timely resolution of problems, regular reporting, and routine independent audits.     

WATERSHEDSS: A DECISION SUPPORT SYSTEM FOR WATERSHED-SCALE NONPOINT SOURCE WATER QUALITY PROBLEMS1

ABSTRACT: A significant portion of all pollutants entering surface waters (streams, lakes, estuaries, and wetlands) derives from non-point source (NPS) pollution and, in particular, agricultural activities. The first step in restoring a water resource is to focus on the primary water quality problem in the watershed. The most appropriate NPS control measures, which include best management practices (BMPs) and landscape features, such as wetlands and riparian areas, can then be selected and positioned to minimize or mitigate the identified pollutant(s). A computer-based decision sup. port and educational software system, WATERSHEDSS (WATER, Soil, and Hydro-Environmental Decision Support System), has been developed to aid managers in defining their water quality problems and selecting appropriate NPS control measures. The three primary objectives of WATERSHEDSS are (1) to transfer water quality and land treatment information to watershed managers in order to assist them with appropriate land management/land treatment decisions; (2) to assess NPS pollution in a watershed based on user-supplied information and decisions; and (3) to evaluate, through geographical information systems-assisted modeling, the water quality effects of alternative land treatment scenarios. WATERSHEDSS is available on the World Wide Web (Web) at http://h2osparc.wq.ncsu.edu .     

MONITORING TRANSIENT WATER QUALITY EVENTS ELECTRONICALLY1

ABSTRACT: Electronic instruments are ideally suited to gathering information regarding transient events. Data loggers equipped with water quality sensors offer an opportunity to study events on fine time scales which cannot be sampled using other means. The utility and significance of this type of data gathering is illustrated with data gathered from two small streams. Three examples are used to illustrate some types of transients that can be observed using electronic data acquisition techniques.