NITROGEN AND PHOSPHORUS DATA FOR SURFACE WATER IN THE UPPER COLORADO RIVER BASIN, COLORADO, 1980-94 National Water-Quality / Assessment Study Unit U.S. GEOLOGICAL SURVEY Open-File Report 97-233 NATIONAL WATER-QUALITY ASSESSMENT PROGRAM Nitrogen and Phosphorus Data for Surface Water in the Upper Colorado River Basin, Colorado, 1980-94 By Kirby H. Wynn and Norman E. Spahr U.S. GEOLOGICAL SURVEY Open-File Report 97-233 Denver, Colorado 1997 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. For additional information write to: Copies of this report can be purchased from: District Chief US. Geological Survey U.S. Geological Survey Information Services Box 25046, Mail Stop 415 Box 25286 Denver Federal Center Federal Center Denver, CO 80225-0046 Denver, CO 80225 FOREWORD The mission of the U.S. Geological Survey l Describe how water quality is changing over (USGS) is to assessthe quantity and quality of the time. earth resourcesof the Nation and to provide informa- l Improve understandingof the primary natural tion that will assistresource managersand policy- and human factors that affect water-quality makers at Federal, State, and local levels in making conditions. sound decisions. Assessmentof water-quality condi- This information will help support the development tions and trends is an important part of this overall and evaluation of management,regulatory, and moni- mission. toring decisionsby other Federal, State, and local agenciesto protect, use, and enhancewater resources. One of the greatestchallenges faced by water- The goals of the NAWQA Program are being resourcesscientists is acquiring reliable information achievedthrough ongoing and proposed investigations that will guide the use and protection of the Nation’s of 59 of the Nation’s most important river basins and water resources.That challenge is being addressedby aquifer systems,which are referred to as study units. Federal, State, interstate, and local water-resource These study units are distributed throughout the agenciesand by many academicinstitutions. These Nation and cover a diversity of hydrogeologic settings. organizations are collecting water-quality data for a More than two-thirds of the Nation’s freshwater use host of purposesthat include: compliancewith permits occurs within the 59 study units and more than two- and water-supply standards;development of remedia- thirds of the people served by public water-supply tion plans for specific contamination problems; opera- systemslive within their boundaries. tional decisions on industrial, wastewater,or water- National synthesisof data analysis, basedon supply facilities; and researchon factors that affect aggregationof comparableinformation obtained from water quality. An additional need for water-quality the study units, is a major component of the program. information is to provide a basis on which regional- This effort focuseson selectedwater-quality topics and national-level policy decisionscan be based.Wise using nationally consistentinformation. Comparative decisions must be basedon sound information. As a studieswill explain differences and similarities in society we need to know whether certain types of observedwater-quality conditions among study areas water-quality problems are isolated or ubiquitous, and will identify changesand trends and their causes. whether there are significant differences in conditions The first topics addressedby the national synthesisare among regions, whether the conditions are changing pesticides,nutrients, volatile organic compounds, and over time, and why these conditions changefrom aquatic biology. Discussionson these and other water- place to place and over time. The information can be quality topics will be published in periodic summaries used to help determine the efficacy of existing water- of the quality of the Nation’s ground and surface water quality policies and to help analystsdetermine the as the information becomesavailable. need for and likely consequencesof new policies. This report is an element of the comprehensive To addressthese needs, the U.S. Congressappropri- body of information developedas part of the NAWQA ated funds in 1986 for the USGS to begin a pilot pro- Program. The program dependsheavily on the advice, gram in sevenproject areasto develop and refine the cooperation,and information from many Federal, National Water-Quality Assessment(NAWQA) State,interstate, Tribal, and local agenciesand the Program.In 1991, the USGS beganfull implementation public. The assistanceand suggestionsof all are of the program. The NAWQA Programbuilds upon an greatly appreciated. existing baseof w ater-quality s tudiesof the USGS, as well as those of the Federal, State, and local agencies.. Federal,State, and local agencies. the are to: The objectives of the NAWQA Program are to oDescibe current water-quality conditions for a Describe current water-quality conditions for a la Robert M. Hirsch rivers, and aquifers. Chief Hydrologist FOREWORD ill CONTENTS . Foreword................................................................................................................................................................................ 111 Abstract.................................................................................................................................................................................. 1 Introduction ...........................................................................................................................................................................1 Purposeand Scope....................................................................................................................................................... 1 Description of Study Unit ............................................................................................................................................2 Nitrogen and PhosphorusData ..............................................................................................................................................2 Sources......................................................................................................................................................................... 2 Retrieval....................................................................................................................................................................... 2 Screening..................................................................................................................................................................... 2 Compilation .................................................................................................................................................................2 Data-SetSummary ................................................................................................................................................................. 5 Description of Data-SetDiskette ........................................................................................................................................... 14 ReferencesCited.. .................................................................................................................................................................. 14 FIGURES 1. Map showing location of study unit and samplingsites for nutrient datacollection ,................................................ 3 2. Graph showing distribution of samplingdates for National Water Information System(NWIS) and STOrageand RETrieval (STORET) surface-watersites for nutrient datacollection .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 9 TABLES I. Parametercodes for data compiled on data-setdiskette ......................................................................................... 4 2. Site identification numbersand site namesfor map referencenumbers in figure 1 ............................................... 6 3. Number of samplescollected per site andnumber of samplescollected per site for eachof the five combinednutrient parameters................................................................................................................................. 11 [Data-Set Diskette in Pocket] CONVERSION FACTORS AND VERTICAL DATUM Multiply BY To obtain cubic foot per second(fi3/s) 0.028 cubic meter per second mile (mi) 1.609 kilometer Degree Celsius (“C) may be converted to degreeFahrenheit (OF) by using the following equation: “F=(1.8x°C)+32 CONTENTS v Nitrogen and Phosphorus Data for Surface Water in the Upper Colorado River Basin, Colorado, 1980-94 By Kirby H. Wynn and Norman E. Spahr Abstract 1994). A major part of each NAWQA study is retrospectiveanalysis of existing water-quality data. This report documents,summarizes, and The four goals of the retrospective analysis are: provides on 3 S-in. diskette the surface-water 1. Develop an improved conceptual model of spatial data collected from January. 1980 through and temporal patternsof concentrationsand loads August 1994 for nitrogen and phosphorusin the within the study unit; Upper Colorado River Basin from the Colorado- 2. Guide additional data collection; Utah State line to the Continental Divide. Ancillary data for parameters,such as water 3. Contribute data to the National SynthesisProgram temperature, streamflow, specific