Winter Chinook, Steelhead, and Spring Chinook -- Delta Actions Team Real-time Assessments

Assessment for Delta Operations on Salmonids

Final: Tuesday, March 24, 2026 at 3 PM

For more detailed data on salmonid conditions in the Delta see corresponding webpage on SacPAS.

Executive Summary

• Entrainment management season is active.

• Annual Loss: 34 (0.32% of annual loss threshold) natural winter-run, 62 (4.78% of annual loss threshold) hatchery winter-run (Sac River), 213 natural steelhead, 1474 (23.27% of annual loss threshold) hatchery steelhead, 1058 (48.12% of annual loss threshold) spring-run surrogate yearlings (Coleman Late-Fall), and 0 (0.00% of annual loss threshold) spring-run surrogate YOY (Feather River Spring-Run).

• Single-year Incidental Take Limit (ITL) Status: 34 (0.57% of 5,922 ITL) natural winter-run; 62 (4.77% of 1,301 ITL) hatchery winter-run (Sac River); 2 (3.85% of 52 ITL) hatchery winter-run (Battle Creek); 213 (4.02% of 5,294 ITL) natural steelhead.

• Spring-run surrogate ITL status (0.5% per release group, BiOp Table 184): YOY - Feather River Hatchery (2026-03-18): 0 (0% of 4,927 ITL); YOY - Feather River Hatchery (2026-03-19): 0 (0% of 5,245 ITL); Yearling - Coleman NFH (2025-11-13): 9 (1.21% of 717 ITL); Yearling - Coleman NFH (2025-11-17): 0 (0% of 376 ITL); Yearling - Coleman NFH (2025-12-17): 757 (32.29% of 2,344 ITL); Yearling - Coleman NFH (2025-12-22): 257 (84.64% of 304 ITL); Yearling - Coleman NFH (2026-01-08): 35 (12.26% of 286 ITL).

• LAD winter-run presence in the Delta is high based on historical monitoring.

• Steelhead presence in the Delta is high based on historical monitoring.

Natural Winter-run Chinook

Juvenile Production Estimate

The Juvenile Production Estimate for winter-run is 1,057,452 for the current water year.

Current Status

Delta Entry Timing - Historically, as of Mar 23, 74% of length-at-date (LAD) winter-run have entered the Delta based on Knights Landing RST catch, 40% have exited the Delta based on Chipps Island Trawl Catch, and 88% of DNA confirmed winter-run have been salvaged.

Red Bluff Diversion Dam Passage Estimate - As of Mar 18 estimated passage to date of LAD winter-run at Red Bluff Diversion is approximately 4.17 million fish. Note that outmigration timing overlaps with spring-run migrating fish, and true winter-run abundance likely differs from these estimates.

Delta Monitoring - Total catch of LAD winter-run at RSTs at Delta Entry (Tisdale, Knights Landing, Lower Sacramento River) between Mar 10 and Mar 22 is 7 individuals. Total catch at Sacramento Trawl and Beach Seines in the delta between Mar 10 and Mar 23 is 18 individuals. Total catch at Delta Exit at Chipps Island between Mar 10 and Mar 23 is 192 individuals.

Annual Loss

The annual loss threshold for natural winter-run is 1% of the JPE or 10,575 fish. The single-year incidental take limit (ITL) is 0.56% of the JPE (5,922 fish) or 0.36% on a 3-year rolling average (BiOp Table 184). As of March 23, cumulative loss of genetically confirmed winter-run is 34 or 0.32% of the annual loss threshold. Cumulative loss in the past 7 days has been 0.

STARS

The Delta STARS Model is an individual-based simulation model that predicts survival, travel time, and routing of juvenile salmon migrating through the Sacramento–San Joaquin River Delta. This model gives insight into survival and routing patterns of winter-run based on most current conditions.

As of March 23, overall through delta STARS estimated survival probability (with 80% credible intervals) is 0.02 (0-0.05) placing it in the 0th percentile of historical STARS survival estimates for the month of March (WYs 2018-2025). STARS estimated routing and survival probabilities (with 80% credible intervals) into the interior delta are 0.13 (0.1-0.16) and 0.01 (0-0.02), respectively, corresponding to the 60th and 1st percentiles of historical March estimates (WYs 2018-2025).

Hatchery Winter-run Chinook – Sacramento River

Hatchery Releases

Livingston Stone National Fish Hatchery released a total of 466,344 winter-run Chinook salmon (February 18). All fish were 100% CWT-marked production fish released at the Sacramento River at John F. Reginato River Access. Release details are shown in the table below and available on SacPAS.

Juvenile Production Estimate

The Juvenile Production Estimate for hatchery winter-run (Sacramento River releases) is 130,096 for Livingston Stone releases. The annual loss threshold is 1% of the JPE (1,301 fish), which is the same as the single-year ITL (BiOp Table 184).

Annual Loss

As of March 24, cumulative loss of Livingston Stone hatchery fish (Sacramento River releases) is 62 or 4.78% of the annual loss threshold (which equals the single-year ITL). Cumulative loss in the past 7 days has been 0.

Hatchery Winter-run Chinook – Battle Creek

Hatchery Releases

Livingston Stone National Fish Hatchery released a total of 207,067 winter-run Chinook salmon into Battle Creek (February 19). Release details are available on SacPAS.

Juvenile Production Estimate

The Juvenile Production Estimate for hatchery winter-run released into Battle Creek is 5,186 based on 207,067 fish released. The single-year incidental take limit (ITL) is 1.0% of the JPE (52 fish) or 0.8% on a 3-year rolling average (BiOp Table 184).

Incidental Take

As of March 24, cumulative loss of Livingston Stone hatchery fish (Battle Creek releases) is 2 or 4.47% of the single-year ITL (52 fish). Cumulative loss in the past 7 days has been 0.

Natural-origin Central Valley Steelhead

Current Status

Delta Entry Timing - Historically, as of Mar 23, 59% of CCV steelhead have entered the Delta based on Knights Landing RST catch, 45% have exited the Delta based on Chipps Island Trawl Catch, and 48% have been salvaged.

Delta Monitoring - Total catch of unclipped steelhead at RSTs at Delta Entry (Tisdale, Knights Landing, Lower Sacramento River) between Mar 10 and Mar 22 is 1 individuals. Total catch at Sacramento Trawl and Beach Seines in the delta between Mar 10 and Mar 23 is 0 individuals. Total catch at Delta Exit at Chipps Island between Mar 10 and Mar 23 is 0 individuals.

Annual Loss

As of March 23, cumulative loss of unclipped steelhead is 213 or 4.02% of the single-year incidental take limit (ITL). There is no annual loss threshold for natural steelhead. The single-year ITL is 5,294 juveniles or 2,319 juveniles as a 3-year rolling average (BiOp Table 184). Cumulative loss in the past 7 days has been 63.

Hatchery-origin Central Valley Steelhead

Surrogate Releases

There have been a total of 9 releases totaling 1,535,164 steelhead in Water Year 2026. JPE for the hatchery releases as of today is 633,352 based on estimated survivals using forecasted water year types (see details in table below). The annual loss threshold, equal to 1% of the JPE, is currently 6,334, but is subject to change with additional steelhead releases.

Total loss of hatchery-origin steelhead is 1474 or 23.27% of the annual loss threshold. Note that hatchery origin of salvaged fish cannot be determined at this time and salvage is based on the assumption of similar routing and survival probabilities of individual hatchery releases.

Spring-run Chinook

Current Status

Delta Entry Timing - Historically, as of Mar 23, 12% of LAD spring-run have entered the Delta based on Knights Landing RST catch, 1% have exited the Delta based on Chipps Island Trawl Catch, and 5% have been salvaged.

Red Bluff Diversion Dam Passage Estimate - As of Mar 18 estimated passage to date of LAD spring-run at Red Bluff Diversion is approximately 0.04 million fish. Note that outmigration timing overlaps with winter-run and fall-run outmigration, and true spring-run abundance likely differs from these estimates.

Delta Monitoring - Total catch of LAD spring-run at RSTs at Delta Entry (Tisdale, Knights Landing, Lower Sacramento River) between Mar 10 and Mar 22 is 60 individuals. Total catch at Sacramento Trawl and Beach Seines in the delta between Mar 10 and Mar 23 is 26 individuals. Total catch at Delta Exit at Chipps Island between Mar 10 and Mar 23 is 101 individuals.

Spring-run Surrogate Releases

A total of 2,839,595 spring-run surrogate fish have been released in Water Year 2026, with an estimated Juvenile Production Estimate (JPE) of 954,564 fish entering the Delta. This includes 805,323 Coleman Late-Fall Run Chinook yearlings (JPE: 219,852) released from Coleman National Fish Hatchery across 12 coded-wire tag groups, and 2,034,272 Feather River Hatchery Spring-Run young-of-year (JPE: 734,712) across 5 coded-wire tag groups. See details in table below.

Annual Loss

The annual loss threshold (Action 5) is 1% of the JPE entering the Delta, tracked cumulatively but separately for yearlings and young-of-year. Yearling surrogates (Coleman Late-Fall): the threshold is 2,199 fish; as of March 23, cumulative loss is 1,058 fish or 48.12% of the threshold. YOY surrogates (Feather River Spring-Run): the threshold is 7,347 fish; as of March 23, cumulative loss is 0 fish or 0.00% of the threshold. The single-year incidental take limit (ITL) is 0.5% of the estimated number of each surrogate release group (BiOp Table 184). ITL status by release group: YOY - Feather River Hatchery (2026-03-18, Production): 0 loss of 4,927 ITL (0%); YOY - Feather River Hatchery (2026-03-19, Production): 0 loss of 5,245 ITL (0%); Yearling - Coleman NFH (2025-11-13, Production): 9 loss of 717 ITL (1.21%); Yearling - Coleman NFH (2025-11-17, Experimental): 0 loss of 376 ITL (0%); Yearling - Coleman NFH (2025-12-17, Production): 757 loss of 2,344 ITL (32.29%); Yearling - Coleman NFH (2025-12-22, Experimental): 257 loss of 304 ITL (84.64%); Yearling - Coleman NFH (2026-01-08, Experimental): 35 loss of 286 ITL (12.26%)

Loss Prediction and Trajectories

The following figures display the current loss predictor model outputs for winter-run Chinook salmon and steelhead.

Evaluation

1. What is the probability of exceeding natural or hatchery winter-run Chinook salmon loss thresholds in the upcoming week?

   LOW RISK: Natural winter-run cumulative loss is currently 0.32% of the threshold. LOW RISK: Hatchery winter-run (Sac River) cumulative loss is currently 4.78% of the threshold. LOW RISK: Hatchery winter-run (Battle Creek) cumulative loss is currently 4.47% of the threshold.

2. What is the probability of exceeding spring-run Chinook salmon surrogate loss thresholds (yearling and YOY) in the upcoming week?

   LOW RISK: Spring-run surrogate yearlings (Coleman Late-Fall) cumulative loss is currently 48.12% of the threshold. LOW RISK: Spring-run surrogate YOY (Feather River Spring-Run) cumulative loss is currently 0.00% of the threshold.

3. What is the probability of exceeding natural or hatchery steelhead loss thresholds in the upcoming week?

   LOW RISK: Natural steelhead cumulative loss is currently 4.02% of the threshold. LOW RISK: Hatchery steelhead cumulative loss is currently 23.27% of the threshold.

References

Brodsky, A., Zeug, S. C., Nelson, J., Hannon, J., Anders, P. J., & Cavallo, B. J. (2020). Does broodstock source affect post-release survival of steelhead? Implications of replacing a non-native hatchery stock for recovery. Environmental Biology of Fishes, 103(5), 437–453.

Del Real, S. C., Workman, M., & Merz, J. (2012). Migration characteristics of hatchery and natural-origin oncorhynchus mykiss from the lower mokelumne river, california. Environmental Biology of Fishes, 94(2), 363–375.

Kurth, R. (2013). Downstream migration success of feather river fish hatchery steelhead smolts under different release strategies.

Sandstrom, P. T., Ammann, A. J., Michel, C., et al. (2020). Low river survival of juvenile steelhead in the sacramento river watershed. Environmental Biology of Fishes, 103(5), 531–541.