Author Archives: Tom Cannon

Sacramento River Spring Pulse Flows – 2024

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The US Bureau of Reclamation (Reclamation), in cooperation with other state and federal agencies, conducted two short-term flow release experiments from Shasta Reservoir in the spring of 2024 to help juvenile salmon reach the ocean. 2024 is a relatively wet year, and it follows a very wet year in 2023 that left a lot of water in storage in Shasta and other Reclamation reservoirs.

The peak emigration to the ocean of wild and hatchery spring-run and fall-run salmon smolts usually occurs in the April-May time period, but may extend into June, especially in wetter years. Reclamation and its partners are developing pulse flow prescriptions for a flow management plan as part of the Action for the Long Term Operation of the Central Valley Project and State Water Project. “Spring pulse flows are designed to improve survival rates of outmigrating spring-run Chinook salmon smolts through the Sacramento River.” 1

The major sources of spring-run salmon smolts include Clear, Battle, Deer, Mill, and Butte creeks, and the Feather River Fish Hatchery. These smolts must pass through the lower Sacramento River, Delta, and Bay. The Feather River Fish Hatchery released its smolts into the lower Feather River in mid-March.

Pulse flows from Shasta Dam pass through Keswick Reservoir, a small regulating reservoir immediately downstream of Shasta Reservoir, and then into the Sacramento River. Pulse flows from Keswick Dam at river mile 300 of the Sacramento River also help move juvenile fall-run salmon downstream. Most Sacramento River fall-run salmon spawn and rear in the 20 miles of the river immediately downstream of Keswick Dam. Pulse flows help move juveniles from this reach downstream to reaches where the flow from tributary rivers and streams augments the flow in the mainstem Sacramento.

The goal of the pulse flows was to release extra flow (3000-6000 cfs) from Shasta reservoir to maintain 11,250 cfs below Keswick Dam for several days (see first pulse in Figure 1). With tributary inflow, river flow near Red Bluff 50 miles downstream was about 15,000 cfs during the first pulse. By the time the first pulse reached Wilkins Slough, nearly 200 miles downstream, the overall flow reached 16,000 cfs (Figure 2), after 3000-5000 cfs of agricultural diversions and multiple tributary inflows. At the end of the pulse flow period, Keswick Dam releases were dropped 6000 cfs (see Figure 1). By May 5, Sacramento River flow at Wilkins Slough had dropped about 8000 cfs. Declining tributary inflows and increased diversions also contributed to the lower Wilkins Slough flows following the pulse flow.

Without adequate flow, juvenile salmon have poor survival during their downstream journey. Low flows increase juvenile salmon’s vulnerability to predation. Low flows also contribute to stressful warm water temperatures. On May 1, 2024, water temperature in the river at Sacramento was below 65oF (18oC), with peak catch of juvenile salmon in the trawl survey (Figure 3). In contrast, in critically dry year 2022, May 1 water temperatures exceeded 65oF, with less than half the 2024 river flow (Figure 4). By late May 2022, water temperatures exceeded 70oF.

In conclusion, the releases of pulse flows from Shasta and Keswick reservoirs had very little signature in the lower Sacramento River due to intervening flows and diversions. The pulse flows were most beneficial in the upper river, where they made up a third to half the river flow. In a wet year like 2024, the benefit is somewhat limited by already high natural flows, although any additional pulse flows later this spring could be of greater benefit with expected declining natural flows and higher air temperatures. In contrast, pulse flows in dry years would provide much greater net potential benefit because of poor natural flows and limited reservoir storage.

The net benefits of pulse flows from Shasta Reservoir must also be considered, of course, in combination with Reclamation’s management of agricultural water deliveries and water stored in Shasta Reservoir for summer temperature management.

Figure 1. Streamflow in the upper Sacramento River below Keswick Dam (RM 300) April 19 through May 19, 2024. Note three-day flow pulses beginning April 23 and May 7.

Figure 2. Streamflow in the middle Sacramento River below Wilkins Slough (RM 120) April 19 through May 19, 2024. Note signatures of the three-day flow pulses show up on April 26 and May 10.

Figure 3. Juvenile salmon trawl catches and water conditions near Sacramento in winter-spring 2024. Note flow pulse in late April.

Figure 4. Juvenile salmon trawl catches and water conditions near Sacramento in winter-spring 2022. There were no flow pulses from Keswick Dam until irrigation releases commenced in May. Catch of juvenile salmon ceased once water temperatures reached or exceeded 70oF in late May.

Klamath River Salmon and Steelhead Recovery – The Future

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After dam removal, the plan for recovering Klamath River salmon and steelhead is relatively straightforward.

Oregon is going to focus on watching to see how steelhead repopulate the upper watershed and on having a more active role in developing spring-run Chinook salmon populations.  Without an existing spring-run stock, Oregon will try establishing one by out-planting stock from California’s Trinity River Hatchery.

California will focus on recovery of existing lower river spring-run Chinook and fall-run Chinook, Coho, and steelhead stocks.  The new Fall Creek Hatchery will sustain the fall-run Chinook, Coho, and steelhead stocks formerly produced at the now-closed Iron Gate Hatchery.  Lower and middle river wild spring–run and fall-run Chinook, Coho, and mainstem and tributary steelhead stocks should expand with improved water quality and access to new habitat.  Historical tributaries offer great potential as does the spring-fed reach of the mainstem near the Oregon border.

In the decades ahead, as the populations and habitat recover, state, federal, tribal, and stakeholder groups will work together toward Klamath salmon and steelhead recovery.

There will be a need to coordinate management of the three H’s:  hatcheries, harvest, and habitat.  Existing hatchery programs should be converted to a single conservation hatchery program focused on salmon and steelhead recovery.  Such a program will need a new hatchery to support the recovery of Klamath spring-run Chinook, as in the San Joaquin River Restoration Program.  The Pacific Fishery Management Council and the two states will have to protect the recovering populations with strict harvest regulations.  Considerable funding will be needed to restore fire-damaged and drought-damaged watersheds, former reservoir footprints, mainstem and tributary fish passage, and spawning and rearing habitat.

Water supply management will remain contested and challenging.  Adequate funding, cooperative efforts, and adaptive management will bring success.

Klamath Dam Removal Update – April 6, 2024

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Video Screen Grab of lower Jenny Creek ASSISTED SEDIMENT EVACUATION PROJECT

In a March 20 post, I related events in the Jan-Feb 2024 period of the Klamath Dam Removal Project.  The initial four-reservoir drawdown in January led to abrupt increases in streamflow, suspended sediment, and low dissolved oxygen levels above and below Iron Gate Reservoir (the lower reservoir).  This was followed by lower stable streamflow, high dissolved oxygen, and declining suspended sediment.  Streamflow pulses from upstream Klamath Lake in late February and early March resulted in (short-term) elevated suspended sediment from exposed sediment erosion in the four reservoir reaches.  These circumstances were expected as part of the four Dam Removal Project.

In March, the Assisted Sediment Evacuation Project began in the Jenny Creek floodplain of the Iron Gate Reservoir footprint.   That project has led to lethal doses of suspended sediment (turbidity) in the lower Klamath River below the Iron Gate Dam site (Figures 1-3).  Project approvals, such as the National Marine Fisheries Service’s (NMFS) biological opinion quoted below, included provisions to stabilize sediments after the January drawdown, but not to flush sediments into creeks and the Klamath River.

Post drawdown and dam removal, crews will be working to actively restore the exposed reservoir footprints and tributary mouths that flow into the former reservoirs. To reduce elevated suspended sediment concentrations (SSCs), the Renewal Corporation will take active measures to flush sediment from the reservoirs during drawdown and then immediately begin stabilizing remaining sediment after drawdown has been completed. Revegetation, channel construction, and placement of habitat features such as logs and boulders will minimize erosion and allow passable channels to form in preparation of fish presence. (NMFS Biological Opinion p. 14)

The origin of the high suspended sediment levels was likely from the exposed bed of Iron Gate Reservoir (particularly the Jenny Creek arm), not upstream reservoir erosion during the Klamath Lake flow pulses.  Sediment levels below Iron Gate Dam were low during the flow pulse that diluted the high sediment loads from Iron Gate Reservoir (Figure 1).  Gages below Copco and JC Boyle reservoirs were lower, generally below lethal levels (Figure 4).

Chinook salmon fry are abundant and most prevalent in the lower Klamath River below Iron Gate Dam in late winter (February-March).  Coho and steelhead fry are more abundant later during spring.

The Assisted Sediment Evacuation Project is slated to end on April 15.  I recommend that it cease immediately, with efforts shifted to “stabilizing remaining sediment,” in order to minimize impacts of the project on Klamath River salmon and steelhead.

Figure 1. Turbidity and streamflow in the Klamath River below Iron Gate Dam (rm 193) in January to March 2024. Note turbidity of 300-500 SBU is roughly 1000-2000 mg/l total suspended sediment (TSS). Such levels are considered lethal for juvenile salmon and steelhead.

Figure 2. Turbidity and streamflow in the Klamath River near Seiad Valley below the mouth of the Scott River (rm 145) in March 2024.

Figure 3. Turbidity and streamflow in the Klamath River near Seiad Valley about ten miles upstream from the mouth of the Scott River (rm 145) in March 2024.

Figure 4. Turbidity and streamflow in the Klamath River just upstream of Iron Gate Reservoir and below Copco dams in March 2024.

Klamath River Update – March 2024

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On March 2, CDFW reported the mortality of recently released (Feb. 28) salmon fry from the new Fall Creek Salmon Hatchery located on a Klamath River tributary upstream of the site of the recently removed Iron Gate Dam. The Iron Gate Hatchery located at the foot of the dam site was removed with the dam and replaced by the Fall Creek Hatchery. Mortality of the salmon fry was attributed to gas bubble disease caused by the fry passing through the Iron Gate Dam release tunnel.

Iron Gate Reservoir and the three upstream reservoirs were emptied beginning on January 11 prior to dam removal. As the reservoirs were drained, the gage below Copco Dam picked up a large increase in turbidity with an associated complete loss of dissolved oxygen (Figure 1). Oxygen returned to the water after several days despite continued high turbidity. This indicated the initial dissolved oxygen loss was likely related to the flush of organic sediment from the bottom of the reservoirs as the draining neared completion. After the flows stabilized (Figure 2) and water level in the river had dropped six feet by the end of January, turbidity dropped and stabilized near 3000 mg/l suspended sediment, and normal high dissolved oxygen returned. Turbidity was measured using three parameters (Figure 3).

The hatchery salmon fry released on February 28 were subjected to a Klamath River with elevated turbidity (suspended sediment concentrations above 2000 mg/l). Such concentrations for extended exposure (days) are highly detrimental to salmon fry.1 The combination of high suspended sediment and gas bubble disease likely has contributed to poor juvenile salmon production this year in the lower Klamath River.

The removal of the Klamath River dams will have substantial long-term benefits for salmonids. As the dam removal process proceeds, it is important to mitigate the short-term impacts of high turbidity levels to the degree possible. Continuing high turbidity events (see March levels in Figure 3) do not bode well for hatchery or wild salmon in the Klamath this year. With nearly 4 million juvenile Chinook salmon yet to be released from the Fall Creek Hatchery this year, it would be wise to either wait for next fall to release them or truck the smolts to the Klamath estuary.

Figure 1. Water level, suspended sediment, and dissolved oxygen in the Klamath River above Iron Gate Reservoir and mouth of Fall Creek, January 16 to March 10, 2024.

Figure 2. Streamflow below the Iron Gate Dam site January 1 to March 10, 2024. Source: USGS.

Figure 3. Suspended sediment and turbidity upstream of Iron Gate Reservoir above the mouth of Fall Creek near Copco, January 16 to March 10, 2024.

  1. Newcombe, C.P., and J.O.T. Jensen. 1996. Channel suspended sediment and fisheries: a synthesis for quantitative assessment of risk and impact. North American Journal of Fisheries Management. 16:693-727. ↩

2024 Salmon Season in Doubt

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On March 1, 2024, the California Department of Fish and Wildlife (CDFW) held its CDFW Annual Salmon Information Meeting via a webinar. The prognosis for a 2024 salmon season does not look good.

The closure of all California salmon fishing in 2023 brought an uptick in salmon escapement to 133,000 in the Sacramento River, which is somewhat positive. The forecast for this year’s fishable stock in the ocean (made up of broodyears 2021-2023), however, is not much better than last year’s, with the lingering effects of the 2020-2022 drought. If a normal fishery had been held last year or were to be held this year, the salmon stocks would no doubt fall into an “over-fished” status.

Notable points of interest:

  • Without fishing in 2023, there was an uptick in the relative percentage of four-year-old spawners, especially in the Klamath system. This was likely related to the fishery closure and strong production from broodyear 2019.
  • There seemed to be significant concern that a higher fishable stock level was important for the good of the endangered southern Orca population that feeds primarily on Chinook salmon.
  • The fisheries agencies appear more comfortable with a fishable stock well over 180,000 than with the forecasted 213,000 for 2024. Note that the 2024 forecast was based on jacks from broodyear 2021 that returned in 2023 that were produced in the heart of drought years 2021 and 2022. Jack numbers are representative of age three adult return numbers the following year (2024).
  • Not a word of concern was expressed for protecting wild, natural-born returning salmon.
  • There was no mention of prescribing a mark-selective fishery despite the recent adoption of such a measure for Columbia River Chinook salmon and its universal use in Coho salmon and steelhead fisheries.

Nothing was said about the possibility of at least experimenting with mark-selective fishing, wherein harvest is allowed on fin-clipped hatchery salmon, a practice prescribed with increasing frequency in Pacific Northwest salmon fisheries. I believe the fishable stock (age 2-4) of marked salmon in the ocean in 2024 is about 300,000.1 A mark-selective fishery could harvest 200,000 of these fish without harming spawning stocks of wild or hatchery fish.2

Sport and commercial fishermen should advocate for a mark-selective fishery in 2024 rather than a second consecutive year of a closed fishery. The Pacific Fishery Management Council is setting harvest control rules for California fishing in early March.3