Monitoring juvenile Chinook salmon outmigration using rotary screw traps on the Sacramento River at Knights Landing

Since 1995, the rotary screw traps (RSTs) at Knights Landing have
provided water management agencies an early warning of emigrating
juvenile Chinook salmon (Oncorhynchus tshawytscha) and steelhead
trout (O. mykiss) making their way to the Sacramento-San Joaquin
Delta (Delta). Due to the proximity of the site to other major
tributaries of the Sacramento River, such as the Feather and
American Rivers, it is assumed that salmonids captured at the
Knights Landing RSTs originate from the upper Sacramento River and
its tributaries, a stretch of river that provides spawning and
rearing habitat for all four runs of natural origin Chinook salmon:
winter-run (State and federally listed as endangered), spring-run
(State and federally listed as threatened), late fall-run and
fall-run, as well as steelhead trout (federally listed as
threatened).  

The near real-time information RST monitoring data provides on
emigration timing and relative abundance for protected runs of
juvenile Chinook salmon and steelhead improves the ability for
resource agencies and water managers to implement protective
measures that help them navigate through the maze of waterways in
the Delta. By utilizing emigration data in adaptive management,
reservoir releases, export rates, water transfers, and Delta Cross
Channel Gate operations can be modified to minimize the risk of
predation, entrainment, and take, thereby maximizing juvenile
salmonid survival through the Delta.   

The primary goals of the Knights Landing Monitoring Program are to
(1) Provide early warning of listed salmonids emigrating toward the
Delta, (2) Document passage of emigrating salmonids including
timing, relative abundance, and environmental conditions, (3)
Develop passage estimates of salmonids emigrating through the lower
Sacramento River above the Delta, and (4) Develop a long-term
dataset on juvenile salmonid emigration to compare changes over
time.

The California Department of Fish and Wildlife (CDFW) issued ITP
2081-2019-066-00 to DWR on March 31, 2020, for the long-term
operation of the State Water Project (SWP) in the Delta. Condition
7.5.2 of the ITP requires the development and establishment of a
spring-run Chinook salmon juvenile production estimate (JPE) to
increase understanding of the impacts water operations have on the
spring-run Chinook salmon population in the Sacramento River
watershed and inform the development of minimization measures to
reduce take of spring-run Chinook salmon at Delta fish salvage
facilities. Data from the Knights Landing RST will be used along
with other datasets from juvenile salmonid monitoring programs in
the Sacramento River Watershed to inform the development of JPE
modeling approaches.

Salmonid data collected from the Knights Landing RST, among other
datasets, is also used by the Salmon Monitoring Team (SaMT) to
understand the movement of juvenile salmon in the Sacramento River
Watershed to estimate the number of winter-run and spring-run
Chinook salmon that have entered the Delta. SaMT is a real-time
operations monitoring team required by Condition of Approval 8.1.2
of the ITP which meets weekly from October through June, to provide
advice for real-time management of SWP operations to DWR, CDFW, and
the Water Operation Management Team (WOMT) to minimize take of
winter-run and spring-run Chinook salmon in the Delta.

Note: data within the current year’s monitoring season are
considered provisional.