Potential pesticide transport in Colorado agriculture: a model comparison

.30 September 1989.Includes bibliographical references (pages [50]-52)Grant no. 14-08-0001-1551, Project no. 09; financed in part by the U.S. Department of the Interior, Geological Survey, through the Colorado Water Resources Research Institute

Statistical and economic considerations for improving regulatory water quality monitoring networks

Fall 1978.Includes bibliographic references (pages 111-114).The assignment of sampling frequencies in regulatory water quality monitoring networks has often been performed with little or no statistical or cost-effectiveness analysis. The research effort described here has attempted to address this problem through the development of appropriate statistical and economic analysis tools which might be applied by regulatory agencies. A technique is presented for predicting confidence interval widths about annual means or annual geometric means for water quality constituents while considering (1) serial correlation and (2) seasonal variation of the quality time series. These two effects are quantified by fitting deterministic seasonal models and time series models of the autoregressive-moving average type to historic water quality records. The statistical tools are illustrated via application to three sets of water quality observations, and the consequences of applying more elementary statistical tools in the determination of confidence interval widths are then examined. A dynamic programming algorithm is developed to assign sampling frequencies throughout a network in order to achieve desirable confidence Interval widths about annual geometric means for selected quality constituents while operating within a fixed budget. The use of the algorithm is illustrated through an application, and a sensitivity analysis is performed to study the effect of variation in values of input variables on the results of the dynamic programming solution

Design of a water quality information system for source water assessment: a Denver water case study, Denver, Colorado

December 2003.Includes bibliographical references (pages 65-66).The questions water quality information systems are being called upon to answer are changing as the management of water quality shifts from a historically point source control framework to investigation of non point sources of pollution. A specific example is that of large Public Water Systems (PWS), providers of drinking water to the public within larger municipalities, who have managed the quality of the source water, from which they draw their supplies, primarily at the intake to the treatment system. In the case of contamination, the potential of finding a new source of supply is rare for large PWSs and thus new emphasis is placed on protection of current supplies to diminish the risk of contamination. This idea of moving farther up into the watershed for water quality management of drinking water supplies is presented by the U.S. Environmental Protection Agency (USEPA) in the Source Water Assessment and Protection (SWAP) program. This thesis proposes a process by which a large PWS can incorporate existing knowledge concerning water quality monitoring into a practical application for production of usable, defensible information used in the management of water quality. The source water quality monitoring system for Denver Water, a large PWS serving the City and County of Denver, Colorado and surrounding areas, is reviewed within this work. The review is presented as an updated water quality monitoring design for Denver Water’s entire source area. The emphasis of the design is placed on the need to connect the information needs of management, in this case Denver Water, with the feasible products of water quality monitoring. Analysis was conducted to determine reasonable sampling frequencies for estimation of mean concentrations, trends, and pollutant loads for physical and chemical water quality parameters identified. Additionally, 48 sampling sites were selected for the source area of approximately 2.5 million acres. In the end, Denver Water is presented a functional monitoring system which enables information production to meet needs for management of the vast area from where they draw drinking water

AGRICULTURAL AND FOREST METEOROLOGY ELSEVIER Application of geostatistics to evaluate partial weather station networks

Abstract Climatic data are art essential input for the determination of crop water requirements. The density and location of weather stations are the important design variables for obtaining the required degree of accuracy of weather data. The planning of weather station networks should include economic considerations, and a mixture of full and partial weather stations could be a cost-effective alternative. A 'full' weather station is defined here as one in which all the weather variables used in the modified Penman equation are measured, and a 'partial' weather station is one in which some, but not all, weather variables are measured. The accuracy of reference evapotranspiration (Et r) estimates for sites located some distance from surrounding stations is dependent on measurement error, error of the estimation equation, and interpolation error. The interpolation error is affected by the spatial correlation structure of weather variables and method of interpolation. A case-study data set of 2 years of daily climatic data (1989)(1990)) from 17 stations in the states of Nebraska, Kansas, and Colorado was used to compare alternative network designs and interpolation methods. Root mean squared interpolation error (RMSIE) values were the criteria for evaluating Et r estimates and network performance. The kriging method gave the lowest RMSIE, followed by the inverse distance square method and the inverse distance method. Co-kriging improved the estimates still further. For a given level of performance, a mixture of full and partial weather stations would be more economical than full stations only

Impact of irrigation water use on water quality in the Central Colorado Water Conservancy District

December 15, 1993.This publication is a product of the Natural Resources Law Center, a research and public education center at the University of Colorado School of Law.Includes bibliographical references (page 25).This paper presents the results of a two year study sponsored by the Colorado Water Resources Research Institute, the United State Geological Survey, and the United States Environmental Protection Agency on the impact of irrigation water use on water quality in the agricultural area near Greeley, Colorado. Data on water management techniques, consumptive use, irrigation application efficiency, deep percolation, surface runoff and nitrate levels were collected. Results indicated a wide range of application efficiencies and deep percolation percentages. Nitrate levels in the pumped ground water often exceeded EPA drinking water standards, while nitrate levels of water from the South Platte River were generally below the drinking water standards. There are opportunities for improving irrigation application efficiency in this area, but there may be repercussions for downstream water users. Decreasing the quantity of nitrate going into the ground water can occur through increased water conservation and through reducing the actual amount of nitrates applied in the irrigation water or fertilizers. There is currently little incentive for farmers to implement these measures.Grant no. 14-08-0001-G2008-2, Project no. 02; financed in part by the U.S. Dept. of the Interior, Geological Survey, through the Colorado Water Resources Research Institute

Multivariate methods for detecting water quality trends

Prepared for Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Corvallis, Oregon.Includes bibliographical references (pages 40-41)

Screening methods for groundwater pollution potential from pesticide use in Colorado agriculture

31 December 1990.Includes bibliographical references.Grant no. 14-08-0001-G1551-01, Project no. 02; financed in part by the U.S. Department of the Interior, Geological Survey

Monitoring strategies for groundwater quality management

April 1986.Bibliography: pages 103-104.U.S. Geological Survey Grant no. 14-08-0001-G-1060