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)

Sacramento River Trace Metals Study

The Sacramento River Trace Metals Study was completed in cooperation with the Sacramento Regional County Sanitation District, the U.S. Environmental Protection Agency, and other state and federal agencies. The study was designed to operate in parallel with NAWQA sampling, but to greatly enhance the sampling, analysis, and interpretation of the presence and transport of trace metals in this river system. Metal transport from an acid mine drainage site (Spring Creek, see map below) and the occurrence of mercury within the main stem of the Sacramento River below Shasta Lake were investigated as part of this study. Samples were collected under both low flow (primarily collected during the months of May, June, July, or September) and stormwater runoff conditions (primarily collected during the months of December and January). One set of samples was collected shortly after a major flood that affected a large part of the Sacramento River Basin on January 1, 1997. The distribution, fate, and transport of metals in the Sacramento River were studied using a multidisciplinary approach that included water, sediment, and biological sampling. Metals were analyzed in whole water samples, in conventionally filtered samples, in colloids, and in ultra-filtered water. The metals were analyzed by the National Research Program Laboratory of the U.S. Geological Survey located in Boulder, Colorado. Colloids are defined as particles with a size greater or equal to 10,000 daltons or a nominal size of 0.005 micrometers. Ultra-filtered water is that which only has particles less than 10,000 daltons or a nominal size of 0.005 micrometers. Streambed samples were also collected as part of this study and selective extractions of colloid samples were completed. The selective extractions were designed to show what possible solid phases the metals were associated with. The possibilities included easily reducible solid phases, oxidizable solid phases, and residual solid phases. The goals of the selective extractions were to assess possible mineralogical residences of the trace elements or to determine how easily the metals could be mobilized from solid phases. Complete details of the field and laboratory methods used to acquire these data are available in Alpers and others, (2000). Please refer to the Selected References.

The sites that were investigated for this study are shown in the following map.

Several types of data collected during this project are available in downloadable files. All data spreadsheets available on this page were prepared with Microsoft Excel and are available in compressed (zip) format. After downloading, the files must be expanded with the appropriate software. The uncompressed files are Microsoft Excel workbooks.

• Explanations of all headers in these spreadsheets are available in this downloadable (zip format) Word document.


• Quality control data that are available include the results of an Environmental Protection Agency laboratory evaluation, the analysis of standard reference material, and the results of equipment and field blank analyses.


• Field measurements, anions, nutrients, and organic carbon data are available. Most measurements, unless specified in the spreadsheet, are for filtered water samples.


• Trace elements and select major elements were analyzed in whole water samples and in filtered water samples. The spreadsheet for filtered water samples holds data for various types of filtration methods. The headers and abbreviations used in these spreadsheets are described in the Word document previously mentioned.


• Lead concentrations in filtered water samples were determined on separate samples of water using a dedicated bottle. The dedicated bottle was necessary to prevent contamination of water samples by atmospheric lead.


• Metal concentrations in colloids, and colloid and suspended sediment concentrations were measured as part of this study. Colloids were recovered from large volume water samples (up to 100 liters) using tangential flow filtration.


• Sequential extractions of metals in colloids were completed to determine what potential solid phases the trace metals might be associated with and to determine the relative strength of binding of various metals within the colloids.


• Trace elements in streambed sediments were measured at eight sites on the Sacramento River and on a tributary to the Sacramento River. All measurements were made on sediment that had been sieved through a 63-micrometer screen.

Spring Creek site photos