Listed Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) spawn and rear in the Sacramento
River and its tributaries; adult fish use the mainstem Sacramento River for upstream migration to spawning sites and juvenile fish use the river for downstream outmigration to the Pacific Ocean in winter and spring. During their outmigration, juvenile salmonids encounter alternative migration pathways through the Sacramento-San Joaquin Delta (Delta), e.g., Sutter and Steamboat sloughs, the Delta Cross Channel (DCC) to Snodgrass Slough and the North and South forks of the Mokelumne River, Georgiana Slough to the North Fork Mokelumne River, and Threemile Slough. Figure ES-1 shows the migration pathways in the north and east Delta for outmigrating salmonids, the location of the DCC, and the locations of the pumping facilities of the State Water Project (SWP) and the federal Central Valley Project (CVP) in the south Delta.
The National Marine Fisheries Service’s (NMFS) 2009 Biological and Conference Opinion for the Long-Term
Operations of the Central Valley Project and State Water Project (BiOp) requires the California Department of
Water Resources (DWR) and the U.S. Bureau of Reclamation (Reclamation) consider engineering solutions to reduce the diversion of salmonids from the Sacramento River into the central (also called the ‘interior’ Delta) and south Delta where the potential for entrainment at the SWP and CVP pumping facilities increases. One of several locations identified in the BiOp for engineering solutions evaluation is Georgiana Slough, a natural distributary of the Sacramento River. The outmigration of salmonids into the interior Delta through pathways such as Georgiana Slough has been shown to contribute to greater mortality.
In an effort to identify potential engineering approaches to reduce the percentage of salmonids that migrate from the Sacramento River into Georgiana Slough, DWR implemented a large-scale testing program in 2011 and 2012 to assess the effectiveness of a non-physical barrier design (i.e., a Bio-Acoustic Fish Fence, or BAFF). The experimental design of the 2011 and 2012 tests used acoustically tagged juvenile Chinook salmon and steelhead (2012 only), released upstream of the BAFF when the barrier was ‘On’ and ‘Off’ (i.e., in operation or not in operation, respectively), to determine the effectiveness of the barrier. In 2014, a physical barrier called a Floating Fish Guidance Structure (FFGS) was tested, with methods similar to those used during the testing of the BAFF barriers in 2011 and 2012. This report presents the results of the tests conducted in 2014 using the FFGS (2014 GSFFGS Study).
Georgiana Slough Barrier Study Reports
Georgiana Slough Barrier Environmental Documents
Requests for information and questions concerning Georgiana Slough Barrier Study may be directed to:
Ryan Reeves, PE
South Delta Management
California Department of Water Resources
1416 Ninth Street
Sacramento, CA 95814
Telephone: (916) 653-6868
FAX: (916) 653-6077