Synthesis Reports

In an ongoing effort the TRRP is compiling data and reports across years and topics to address specific scientific and public questions related to Trinity River restoration. The reports below were developed to promote understanding of key topics for restoration of the river and its fisheries.  Some of these reports come from a specific task to provide cohesive, summary reports (synthesis reports) on various restoration topics, while others were completed separately but address topics of a similar nature.  TRRP produces many other reports that will not be listed here (see

These reports are organized according to three categories that can be used to monitor responses to restoration actions: 1) Physical, 2) Water Temperature, 3) Fisheries, and 4) Riparian and Biological.

Check back from time to time, as the list will expand. See also our 2021 Science Symposium page, which has presentations on some of these and other upcoming synthesis reports.

Physical (Ordered with the most recent first):

Redd and salmon carcass surveys 2016.

Partners with the TRRP complete salmon redd and carcass surveys annually on the Trinity River.

Water Temperature (ordered with the most recent first)

  • Asarian, J. E., K. De Juilio, S. Naman, D. Gaeuman, and T. Buxton. 2023. Synthesizing 87 years of scientific inquiry into Trinity River water temperatures. Report for the Trinity River Restoration Program (TRRP). Riverbend Sciences, Eureka, California.
    • This major compilation of water temperature data provides a number of findings relevant to current water management practices including deviations from natural river temperatures in winter and in late spring that likely impact salmonids and other riverine wildlife.

Fisheries (ordered with the most recent first)

  • Gaeuman, D., K. De Juilio, and T. Buxton. 2023. Stream bed disturbance and risk of salmonid redds scour in the Trinity River, CA. Report for the Trinity River Restoration Program (TRRP). Yurok Tribe Fisheries Department, Weaverville, California.
    • Scouring of salmon redds was a big concern for a long time, and used as a reason for avoiding large dam releases during winter.  This report analyses the positioning of redds relative to where scour can be expected and finds that the risk of scouring is low.
  • Pinnix, W. D., S. P. Boyle, T. Wallin, T. Daley, and N. A. Som. 2022. Long-Term Analyses of Estimates of Abundance of Juvenile Chinook Salmon on the Trinity River, 1989-2018. Arcata Fisheries Technical Series Report TS 2022-40, report for the Trinity River Restoration Program (TRRP). U.S. Fish and Wildlife Service, Arcata, California.
    • Analyzing 30 years of data, this report finds a shift in abundance of juvenile salmon that corresponds to the initiation of restoration flows. However, growth of juvinile Chinook seems to be reduced, possibly due to colder water temperatures.
  • Cooper-Hertel, E., D. Gaeuman, K. De Juilio, A. Martin, J. Boyce, D. H. Goodman, N. Som, and J. Alvarez. 2022. Trinity River Juvenile Salmonid Habitat Synthesis: Physical Habitat Capacity at the Restoration Site and Reach Scale. Report for the Trinity River Restoration Program (TRRP). Klamath, California.
    • An analysis across the restoration reach looking into flows, physical terrain, hydraulics, and fish distribution. Findings indicate that while slight increases to winter baseflows (e.g. 500) cfs can minorly reduce juvenile fish habitat, greater increases can increase habitat. Also channel restoration that results in greater habitat complexity also increases fish habitat.
  • Cooper-Hertel, E. J., K. T. Lindke, T. Daley, K. De Juilio, and K. Hopkins. 2022. Assessing temperature regimes and juvenile Chinook Salmon growth in Trinity River off-channel and mainstem habitats. Report for the Trinity River Restoration Program (TRRP). Yurok Tribe Fisheries Department, Klamath, California.
    • This study demonstrated that off-channel habitats for juvenile fish can provide more appropriate water temperatures to enable more optimal growth when fish are able to access such habitats.
  • Thomas Gast & Associates. 2021. Analysis and model evaluation of long-term data collected at the Willow Creek outmigrant trap. Report 20190910YTFP for the Trinity River Restoration Program (TRRP). Thomas Gast & Associates Environmental Consultants, Arcata, California.
    • This analysis of juvenile Chinook growth and the timing of their outmigration, relative to flows and water temperatures, found that early spring flows correspond to better consumption and growth conditions while the cold temperature of releases in May corresponds to lower consumption and growth, suggesting the need for better control of the temperature of water released from the reservoirs.
  • Boyce, J., D. H Goodman, N. A Som, J. Alvarez, K. Hopkins, and A. Martin. 2020. Streamflow and Juvenile Salmonid Habitat Availability at Six Rehabilitation Sites on the Trinity River, California 2008-2017. Arcata Fisheries Technical Report Number TR 2020-39 for the Trinity River Restoration Program (TRRP). U.S. Fish and Wildlife Service, Arcata, California.
    • Effects of channel rehabilitation on habitat for young fish.
  • Rupert, D. L., S. A Gough, N. A Som, N. J Davids, B. C. Matilton, A. M Hill, and J. L Pabich. 2017. Mainstem Trinity River chinook salmon spawning survey, 2015 and 2016. Arcata Fisheries Data Series Report Number DS 2017-56 for the Trinity River Restoration Program (TRRP). U.S. Fish and Wildlife Service, Arcata, California.
    • Report on changing distribution of spawning in the Trinity River (less crowding in the immediate vicinity of the hatchery).

Riparian & Biological (ordered with the most recent first)

See also our Performance Measures page.