U.S. GEOLOGICAL SURVEY
Water Resources Investigations Report 02-4202
Hydrology and Chemistry of Floodwaters in the
Yolo Bypass, Sacramento River System, California, during 2000
By Laurence E. Schemel, Marisa H. Cox, Stephen W. Hager and Theodore R.
Sommer
Abstract
Discharges to and floodwaters in the Yolo Bypass were sampled during winter
and spring, 2000. The primary purpose of the study was to link changes
in water quality in the Yolo Bypass to inflows from the Sacramento River
(over Fremont Weir) and from four local streams that discharge to the west
side of the floodplain. Specific conductance, chloride, sulfate, dissolved
inorganic nutrients, dissolved organic carbon, particulate carbon and nitrogen,
suspended particulate matter (mass), and selected dissolved metals were measured
in most of the samples. When the Sacramento River was spilling over
Fremont Weir, the water chemistry in the Yolo Bypass was very similar to
that in the river except along the western margin of the floodplain where
influences of local stream inflow were evident. When flow over Fremont
Weir stopped, floodwaters drained from the Yolo Bypass, and the local streams
were the major discharges as the floodwaters receded eventually to the perennial
channel along the eastern margin of the floodplain. After the initial
draining of the floodplain, chemical concentrations at sites along the perennial
channel showed strong influences of inflows from Cache Creek and Ridge Cut,
which are sources of nutrients and contaminants that are potentially hazardous
to wildlife. Runoff from spring storms increased flow in the perennial
channel and flushed accumulated nutrients and organic matter to the tidal
river. Releases of freshwater to the perennial channel might be beneficial
in maintaining habitat quality for aquatic species during the dry seasons.
Contents
Abstract
Introduction
Methods
Results
Discussion
Summary
References Cited
Appendix A: Filtration and Sample Preparation Methods
Appendix B: Illustrations
Appendix C: Tables
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FOR ADDITIONAL INFORMATION CONTACT
Kenneth E. Bencala, kbencala@usgs.gov
Chief, Flow and Geochemical Interactions Project
U.S. Geological Survey, MS 439
345 Middlefield Road
Menlo Park, CA 94025
