When I last updated the status of the winter-run salmon population of the upper Sacramento River in an April 2020 post, trends in spawning escapement indicated the population was recovering in 2018 and 2019 after the poor runs in 2016 and 2017. That trend continued in 2020 and 2021 (Figures 1-3). These recent runs benefited from wet years in 2017 and 2019, and near-normal 2018 that contributed to better natural egg and fry survival as well as hatchery smolt survival. The only negative trend in the adult escapement is the higher proportion of hatchery-produced adults in the recent year returns that reflects the enhanced hatchery efforts¹ during and after the 2013-2015 drought. The prognosis for the 2022 run remains good, as 2019 was a wet year and 2020 was near normal. Both years had flow and water temperature much better than during the 2013-2015 drought.

The prognosis for the 2023 and 2024 runs does not look as good, given the extreme drought conditions in 2021 that have likely limited survival of the 2021 brood year.² Reclamation undertook unusual operations in 2021 in an attempt to maintain a modicum of winter-run egg and fry survival given the drought conditions (Figure 4). The first indicator of potential success is from screw trap collections at Red Bluff that indicate survival in 2021 has been better than 2015 but poorer than 2018 and 2019 (Figures 5-8). The screw trap collections also produce an end-of-season estimate of total passage (Figure 9), which is another way of summarizing these same data. These indices also show a post-drought recovery from 2018-2020, where 2021 brood-year production would likely fall back to a level below brood year 2018.

In a recent post, the Northern California Water Association (NCWA) expressed a more upbeat prognosis, although tempered by poor drought year 2021 conditions.

“To be sure, the dry and hot conditions in 2021 are not ideal for salmon nor any other part of the ecosystem that depends upon water and they are having challenging years. Yet, despite these dry and hot conditions, salmon are amazingly resilient and they: 1) have returned to the Sacramento Valley in record numbers; 2) will continue to spawn, and 3) are now beginning their journey down the river in large numbers. Importantly, there continues to be a concerted effort throughout the region to improve conditions for every freshwater life-cycle stage of all four runs of Chinook salmon.”

I generally agree on item 3, noting that “large numbers” are relative, as discussed above and shown by comparing the figures below. I do not agree with the other assertions. Much of the “record number” are hatchery fish, as also discussed above. And spawning conditions in the Sacramento River for the rest of the fall will be poor.

NCWA is one of the major users of Sacramento River water. High drought-year allocations of Shasta storage to NCWA users led to high spring demands on storage by NCWA water users (see Figure 4) and in part to the current near-record-low storage in Shasta Reservoir (Figure 10). Unless it rains and snows a considerable amount this winter, salmon and water users will be in dire straits next year.

Figure 1. Winter-run Chinook salmon escapement (run size) to the Sacramento River 1974-2020. (Source: CDFW)

Figure 2. Winter-run Chinook salmon annual aerial redd counts in the upper Sacramento River 2003-2021. (Source: CDFW)

Figure 3. Winter-run Chinook salmon annual carcass counts in the upper Sacramento River 2003-2021. (Source: CDFW)

Figure 4. Winter-run Chinook salmon spawning season conditions in the Sacramento River in 2021. River flows at Keswick Dam (KWK, rm 300) and Bend (BND, rm 250). Water temperatures KWK, BND, and Redding (SAC, rm 290; CCR, rm 280).

Figure 5. Juvenile winter-run salmon counts in Red Bluff screw traps 8/1-10/7, 2021.

Figure 6. Juvenile winter-run salmon counts in Red Bluff screw traps 8/1/15-8/1/16.

Figure 7. Juvenile winter-run salmon counts in Red Bluff screw traps 8/1/18-8/1/19.

Figure 8. Juvenile winter-run salmon counts in Red Bluff screw traps 8/1/19-8/1/20.

Figure 9. Estimated total passage past Red Bluff of unclipped (naturally produced) juvenile winter-run salmon for brood years 2006-2020.

Figure 10. Lake Shasta water level conditions in water year 2021-2022 and other water years, plus historical averages. Source: DWR-CDEC.

The first indicators of winter-run salmon spawning survival in the Sacramento River in 2021 indicate poor production, as expected.¹ The drought and Reclamation’s operations in 2021 have provided production levels on par with 2014 and 2015, the last two critical drought years.

Red Bluff screw-trap collections since August 1, 2021 have been very low (Figure 1). The spawning delay in 2021 due to high spring water temperatures and low flows may be delaying downstream movement. However, outmigration patterns are similar to 2014 and 2015 (Figures 2 and 3). Even 2020, a dry year with poor production, had numbers five times higher than 2021 to date (Figure 4). Historical wet years with good production like 2006 had collection numbers ten times higher (Figure 5). There is a slim chance that the spawning delays and low flows of 2021 will provide screw-trap collection patterns similar to 2018, a dry year with a later collection peak (Figure 6).

Regardless of the low fry production, the young winter-run salmon must still make it 300 miles to the ocean this fall and winter, a phenomenal hurdle under the best of circumstances. Low fall flows will make the journey difficult. The class of 2021 will get no help from storage releases. Like almost every other user of California water in the beginning of water year 2022, outmigrating winter-run salmon are wholly dependent on future rain to provide the water they need.

Figure 1. Late summer 2021 catch of salmon fry at Red Bluff traps with water temperature, streamflow, and water turbidity.

Figure 2. The 2014 catch of salmon fry at Red Bluff traps with water temperature, streamflow, and water turbidity.

Figure 3. The 2015 catch of salmon fry at Red Bluff traps with water temperature, streamflow, and water turbidity.

Figure 4. The 2020 catch of salmon fry at Red Bluff traps with water temperature, streamflow, and water turbidity.

Figure 5. The 2006 catch of salmon fry at Red Bluff traps with water temperature, streamflow, and water turbidity.

Figure 6. The 2018 catch of salmon fry at Red Bluff traps with water temperature, streamflow, and water turbidity.

The Problem

The 2021 target upper water temperature limit for salmon spawning and gravel-bed egg incubation below Shasta/Keswick dams on the Sacramento River near Redding was 55^oF.  It is a little late for that now.  Since September 1, Keswick releases have been greater than 56.5ºF, and are now approaching 58ºF.  That’s too warm for the winter-run salmon who have finished spawning (Figures 1 and 2).

But what about the far larger run of fall-run salmon during their peak October spawning?  Can water temperatures downstream of Keswick be lowered back to 55^oF in October?  The answer is a qualified yes.

Figure 1. Daily average water temperature of Sacramento River near Redding (SAC gage), September 1-21, 2021.

Figure 2. Daily average water temperatures from Shasta Dam powerhouse (TCD), immediately below Shasta Dam (SHD), and from Keswick Dam (KWK) to Sacramento River, September 1-21, 2021.

The Solution

A “qualified yes” means it would be a complex undertaking involving two actions possible under Reclamation’s operation of its Shasta/Trinity Division:

1. Switching most or all of Shasta releases to the cold-water lower river outlets of the dam and ceasing warm-water hydropower releases from the dam’s powerhouse.
2. Minimizing warm-water hydropower releases from Whiskeytown Lake to Keswick Reservoir.

Much of the remaining cold-water pool in Shasta Reservoir is being used to overcome warm-water hydropower releases into Keswick Reservoir (~60^oF or higher) before water is released to the Sacramento River below Keswick Dam.  Cutting hydropower releases and rationing the available cold-water-pool supply through Shasta Dam’s lower river outlets is therefore a potential solution to warm water releases to the river.  Though this would reduce hydropower in the short-term, it would save storage in the long-term.

The solution would require a substantial reduction in Shasta Reservoir releases to ensure the cold-water-pool is not exhausted over the next month or more.  However, reducing releases would lower river water levels and strand salmon redds or reduce egg-embryo survival of remaining active winter-run redds or any newly spawned spring-run and fall-run redds.

A possible resolution is to drop flows after the vast majority of winter-run fry have left their redds and before most of the fall-run salmon have spawned.  This has been the standard management approach in many years to save storage – sometime in late September or in October.

Further Context

Under present conditions in late September 2021, access to the cold-water pool in Shasta Reservoir occurs primarily during the afternoon/evening, during peaking-power releases (Figures 3-5) from the penstocks via the Temperature Control Device (TCD) on the face of the dam.  Side-gate openings on the TCD (Figure 6) are able to pull cold water from below only during peak releases.  This pattern indicates that a modified solution might be to reduce warm-water power releases during non-peak operations, while retaining some peaking power releases from Shasta Dam in combination with lower level dam outlet releases.

Figure 3. Hourly flow releases from Shasta Dam September 18-23, 2021.

Figure 4. Hourly water temperature of water releases from Shasta Dam September18-23, 2021.

Figure 5. Hourly water temperature of water releases from a Shasta Dam penstock September18-23, 2021.

Figure 6. Shasta Dam conditions and operation on September 15, 2021.

Earlier this summer, the Bureau of Reclamation’s operations of Shasta Reservoir, under its Drought Plan jointly developed with the California Department of Water Resources (DWR), caused high water temperatures that delayed spawning of winter-run Chinook salmon to early summer (mid-June through mid-July).¹ Winter-run salmon leave the redds after 2-3 months, which in 2021 will mean a mid-August through September peak emergence.

In their Addendum to the State Water Project and Central Valley Project Drought Contingency Plan issued August 31, 2021, Reclamation and DWR state how an increase in September releases responded to a request from fisheries agencies:

In the July Drought Plan update, Reclamation’s forecast for releases to the Sacramento River were 7,850 cfs in August, ramping down to a monthly average of 5,200 cfs in September, and then going back up to 7,550 cfs in October to move the transfer water referenced above. In late August, the fishery agencies reviewed updated data indicating that a flow of approximately 6,800 cfs was needed through early-October to protect several remaining winter-run Chinook salmon redds. As a result, Reclamation modified its previous plan and held releases at 6,800 starting August 26.

Not so fast. In 2021, as in 2014, Reclamation cast the die early in the year, releasing too much water that was too warm until late June (Figures 1 and 2). That was Reclamation’s call, not the choice of the fish agencies. The agencies know that in drought year 2014, Reclamation also maintained both high flow releases and high water temperatures early in the summer, and that therefore the winter-run salmon spawned late. The agencies also know that a drop the water level 2-3 feet at the beginning of September 2014 (Figures 1 and 2) proved catastrophic to eggs and alevin still in the redds. Such drops in water level, with most redds in 1-3 ft of water, cause dewatering, reduced inter-redd water flow, sedimentation within the redd, lower dissolved oxygen, higher redd water temperatures, early hatching, direct egg/embryo mortality, and restricted fry movement within and emergence from redds.

The planned drop in early September of 2-3 feet in water level, part of the original 2021 Drought Plan, was a bad part of bad plan from the get-go. In 2015, Reclamation at least tried to avoid the drop by keeping releases lower throughout the summer (Figures 1 and 2). The August Addendum insinuates that added loss of storage in September-October to maintain higher flow/stage was the result of fishery agency review, when the agencies never wanted nor originally approved the September drop in river flow. The steady flow/stages in 2015 (Figures 1 and 2) was the appropriate prescription.

Just as it was a happy circumstance for the Sacramento River Settlement Contractors that Reclamation delivered them too much water north of the Delta early in the year, it was a happy circumstance for Reclamation and the Settlement Contractors that their planned water transfers of about 200 thousand acre-feet (TAF) to buyers south of the Delta just happened to be ready to go just as the drop planned earlier in the summer was scheduled to happen. Transfer water in a market where prices are north of $1000/AF is the mother’s milk of the change in September Shasta operations (Figure 3).

The accelerated schedule of transfers from Shasta storage also reduces the opportunity for the State Water Board or its Executive Director to wake up and smell the receding predictions for the reservoir’s receding shoreline. The tables at the end of the August Addendum now predict end-of-November storage in Shasta to be an unprecedented 729 TAF, down from the July Addendum’s prediction of 849 TAF. The only numbers that have maintained relative consistency throughout the summer 2021 Sacramento River debacle are the levels of deliveries and transfers. That consistency has been matched and enabled by the silence of the Water Board.

In summary, the original 2021 Drought Plan did not address the real risk of redd stranding that proved devastating for the winter-run salmon spawn in summer 2014. The July-August 2021 stage drop was bad enough and should have been avoided, given that high water temperatures delayed the spawn of winter-run to late June. The fish agencies were cornered into choosing between a large September 1 stage drop in a bad original plan and the buy-now-but-pay-later option of maintaining higher flows through September. The additional drain on Shasta storage and Reclamation’s increasing inability to maintain cold water releases through October show the folly and poor design of the original Drought Plan.

This post is part 3 in a series on DWR and Reclamation’s August Addendum to the 2021 Drought Plan.

• Post 1: Addendum to the State Drought Plan — August 31, 2021, Part 1: the Art of the Euphemism
• Post 2: Addendum to the State Drought Plan – August 31, 2021, Part 2: This Is a Test(?)

Figure 1. River stage below Keswick Dam June-October 2014, 2015, and 2021.

Figure 2. River stage at Bend Bridge, 60 miles below Keswick Dam June-October 2014, 2015, and 2021.

Figure 3: Reclamation’s Delta Exports August 15-September 15, 2021.