Water-Quality Assessment of the Sacramento River Basin, California: Water-Quality, Sediment and Tissue Chemistry, and Biological Data, 1995-1998 (Open-File Report 2000-391)

Introduction

The U.S. Geological Survey (USGS) implemented the National Water-Quality Assessment (NAWQA) Program to describe the status of and trends in the quality of the nation's surface water and ground water and to provide scientific understanding of the natural and human-induced factors that affect water quality. In 1991, twenty study units were started. Additional study units began in 1994 and 1997.

Data collection and analysis in each study unit follows national guidelines for the NAWQA Program, but they may also address the local or regional issues most important to that study unit. NAWQA is designed to produce a wealth of water-quality information to assist policy makers and managers at the national, state, and local levels in making more informed decisions with regard to the concentrations of specific analytes.

In 1994, the Sacramento River Basin study unit team began planning assessment activities. The basin was subdivided into six physiographic subunits and nine ecological subunits that were determined to be the most influential natural factors affecting water quality. Stream sampling began in 1995 and lasted until April 1998. Much of the data collection focused on the Sacramento Valley and Klamath Mountain subunits, but ecological sampling also included the Cascade Mountains and Sierra Nevada subunits. Hundreds of water-quality characteristics were measured in different media during this time, including ground water, stream water, streambed sediments, and aquatic biological tissues. Fish, invertebrate, and algal communities and stream habitat also were sampled or assessed. In addition, spatial data such as geology, land use, hydrography, and other watershed characteristics were compiled into a geographic information system (GIS) to support the assessment. After April 1998, the project entered a period of less frequent sampling called the low-intensity phase.

Purpose and Scope

This report presents data collected and compiled during the first high-intensity phase of the Sacramento River Basin NAWQA study unit. The data are presented in a convenient electronic format suitable for downloading into spreadsheet applications. Data are presented from 78 ground-water wells and 55 stream sites. Ground-water measurements compiled in this report include chemical, physical, and water-level data. Stream water measurements compiled include chemical, physical, streamflow, bed-sediment contaminants, aquatic-tissue contaminants, fish community, invertebrate community, and periphyton algae assemblages. Quality-control chemical data are also presented. All data were collected between 1995 and 1998.

Study Design and Sampling Methods

The study design and sampling methods developed for the Sacramento River Basin NAWQA study unit are consistent with the national NAWQA guidelines (Gilliom and others, 1995, Sheton, 1994). The design permits an integrated assessment of conditions at local, regional, and national scales. A detailed description of the design of the Sacramento River Basin NAWQA study is given in the report, "Water Quality Assessment of the Sacramento River Basin, California–Environmental Setting and Study Design" (Domagalski and others, 1998).

Sampling methods and protocols for the NAWQA Program are documented in a series of guidance documents. Citations for these can be found in the Selected references section of this report. The primary reference for streamwater sample collection methodology is given by Shelton (1994). Streamwater samples are collected using the equal-width-increment (EWI) technique and using a 3-liter Teflon bottle fitted with an isokinetic nozzle. This technique allows for a representative sample to be collected along the stream cross section, both horizontally and vertically. The method has limitations in large rivers, such as the Sacramento River, because of the depth of the water column. For example, the method is valid for sampling the upper 4.6 meters of water colummn, but the Sacramento River is of greater depth at some sampling locations. Sampling to greater depths can result in a biased sample, especially for suspended sediment. As a result, only the upper 4.6 meters of water were sampled, if the overall water depth was greater, on any given sampling event. Samples of streambed sediment were collected according to the methods of Shelton and Capel (1994), Methodology for the collection of ground-water samples is provided by Koterba and others, (1995). Methods for the collection of biological samples are provided by Meador and others (19993a, 1993b), Cuffney and others (1993a, 1993b), and Porter and others, (1993).

Data are also included for the Sacramento River Trace Metals Project. Trace metal occurrence, distribution, and transport were cited as important water quality issues early in the design phase of this project. Because the NAWQA Program only supported limited sampling for trace metals, a separate project was designed in cooperation with the Sacramento County Regional Sanitation District to assess these issues. Water quality and hydrologic data from the Sacramento River Trace Metals Project are included in this report. Interpretative reports from that project are listed in the Selected References.

Note: Use of trade names in this report is strictly for informational purposes and does not constitute endorsement by the U.S. Geological Survey.

Using This Report

The data presented in this report are organized according to the Sacramento River Basin study unit's design. Most of the data can be accessed two ways, viewing the data on screen, in the format of HTML tables, or downloading the data in a tab-delimited format. Most of the downloadable files are in a tab-delimited format. The data can be read into any spreadsheet software application by choosing the tab-delimited option of the chosen software. Some data files are stored in compressed format (zip-format) because of size. The de-compressed files are Microsoft Excel workbooks.

For More Information

This report is being distributed by CD-ROM and on the World Wide Web.
Requests for information or data related to this report should be directed to:

Sacramento River Basin NAWQA Chief
U.S. Geological Survey
Placer Hall, 6000 J Street
Sacramento, California 95819-6129