Hydrology and Hydrodynamics on the Sacramento River Near the Fremont Weir, California—Implications for Juvenile Salmon Entrainment Estimates

Scientific Investigations Report 2018-5115
Prepared in cooperation with the California Department of Water Resources and U.S. Bureau of Reclamation
By: , and 



Estimates of fish entrainment on the Sacramento River near the Fremont Weir are a critical component in determining the feasibility and design of a proposed notch in the weir to increase access to the Yolo Bypass, a seasonal floodplain of the Sacramento River. Detailed hydrodynamic and velocity measurements were made at a river bend near the Fremont Weir in the winter and spring of 2016 to examine backwater conditions and estimate the hydraulic entrainment zone, a zone where fish would be predicted to be entrained into the notch. Secondary circulation near the river bend was shown to shift the velocity and discharge distributions toward the outside of the bend. Variability in the stage-discharge relation was shown to be the biggest source of uncertainty in determining the location of the hydraulic entrainment zone. Outflow from the Sutter Bypass and high flow on the Feather River resulted in backwater conditions near the Fremont Weir about 25 percent of the time over the 27-year period from April 1990–April 2017. Velocity measurements used to estimate the critical streakline position (the outer edge of the hydraulic entrainment zone) were not made over a sufficient range of conditions to explicitly quantify the variability in the location of the critical streakline. The variability in the critical streakline position was therefore represented stochastically with a random effects model. The estimated position of the critical streakline and the random effects model are input parameters used in a simulation designed to estimate fish entrainment over a 15-year period. The estimates of the critical streakline and likely fish entrainment could be much improved with velocity measurements over a broader range of stage and discharge conditions.

Suggested Citation

Stumpner, P.R., Blake, A.R., and Burau, J.R., 2018, Hydrology and hydrodynamics on the Sacramento River near the Fremont Weir, California—Implications for juvenile salmon entrainment estimates: U.S. Geological Survey Scientific Investigations Report 2018–5115, 50 p., https://doi.org/10.3133/sir20185115.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Methods
  • Analysis of Hydrologic Conditions on the Sacramento River Near the Fremont Weir
  • Influence of Secondary Circulation on Velocity and Discharge Distributions
  • Hydraulic Entrainment Zone
  • Conclusions and Recommendations
  • References
  • Appendix. Linear Regression Model to Predict Discharge at the Fremont Weir
Publication type Report
Publication Subtype USGS Numbered Series
Title Hydrology and hydrodynamics on the Sacramento River near the Fremont Weir, California—Implications for juvenile salmon entrainment estimates
Series title Scientific Investigations Report
Series number 2018-5115
DOI 10.3133/sir20185115
Year Published 2018
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) California Water Science Center
Description Report: viii, 50 p.
Country United States
State California
Other Geospatial Sacramento River
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details