Author Archives: Tom Cannon

Hatchery Delta Smelt 2021

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Efforts continue to gain approval for releasing hatchery-raised delta smelt in the San Francisco Bay-Delta Estuary. However, given a poor prognosis for a successful introduction, the chances of approval are not good.1  The biggest obstacle is the absence of a location to release the hatchery-raised fish that will allow their survival and thus contribute to the species’ recovery. Another problem is the potential detrimental effect on the remaining wild smelt from genetic compromise.

To me, the answer to the second issue is clear. With few if any “wild” delta smelt left on Earth, it is essential to get as many hatchery smelt out into the wild as soon as possible to save the species. Let the genetics get worked out later by Mother Nature.

Two locations for release of hatchery smelt seem most plausible: the low salinity zone in the west Delta/eastern Suisun Bay and the Deep-Water Shipping Channel in the north Delta. These are primary late spring and early summer nursery areas that are most likely to have the right habitat conditions (water temperature and low salinity) and food supply. These two locations were the last known concentrations of juvenile delta smelt (Figure 1) from the last strong adult spawn in 2012 (Figure 2).

The better of the two sites is the eastern-Bay/west-Delta location, because the ship-channel gets too warm by summer (Figure 3). In contrast, the region between Collinsville in eastern Suisun Bay and Decker Island in the west Delta is cooler and within the low salinity zone (Figures 4 and 5). A nighttime near-bottom release into cooler, deeper channel waters would give the hatchery smelt at least a minimum opportunity to acclimate to the warm Bay-Delta waters.2

Figure 1. Last known prime late spring and early summer nursery area of delta smelt (2012, 20-mm survey). Red lines denote approximate location of X2 (~2000-4000 EC) at the time.

Figure 2. Adult delta smelt catch index from monthly winter trawl surveys 2002-2021.

Figure 3. Water temperature (ºC) and salinity (EC) in spring 2020 in Deep Water Ship Channel.

Figure 4. Water temperature (C) and salinity (EC) in spring 2021 in Sacramento River channel near Collinsville in eastern Suisun Bay.

Figure 5. Water temperature (ºC) and salinity (EC) in spring 2021 in Sacramento River channel near Decker Island in the western Delta.

Peaking Power at Shasta Dam in Summer 2021 – Saving Winter Run Chinook Salmon

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In a recent 6/13/21 post, I discussed various tradeoffs of Shasta Reservoir operations on water supply deliveries, power production, and salmon survival for summer 2021. In that post I made reference to tradeoffs with peaking power production at the Shasta hydropower system. This post provides more information on those potential tradeoffs.

Peaking Power Production

Peaking power refers to the release of varying amounts of water through power turbines on a within-day schedule to meet the peak power demands of the regional electric grid. Inflows into Keswick Reservoir near Redding show the peaking power production schedule from Shasta Dam and Whiskeytown Dam into Keswick Reservoir on the Sacramento River (Figure 1). Over a recent two-day period, June 12-14 2021, hourly inflows to Keswick Reservoir ranged from 1900 cubic feet per second (cfs) to 17,500 cfs. Peak inflows were in late afternoon and evening, reflecting peak power demands. Minimum inflows were in the early morning, when power demand is low.

Peaking Power and Water Temperature from Shasta Dam

High releases for peaking power at Shasta Dam can draw warm water from near the surface of Shasta Reservoir (Figure 2). Water temperature below the dam increased from 50ºF to 56ºF in the recent example peaking periods, June 12-14. The positive relationship between dam release flow and water temperature is obvious (Figure 3).1

Peaking Power and Water Temperature from Whiskeytown Dam

In contrast to Shasta Dam, there was minimal influence on water temperatures when there were peaking releases from Whiskeytown Dam from June 12-14. The release water temperatures into Keswick Reservoir through the Spring Creek Powerhouse are minimally influenced by the flow rate (Figures 4 and 5). On June 13, there was no peaking through Spring Creek Powerhouse, but there was little variation in water temperature from peaking days on June 12 and 14.

Summary of Shasta-Keswick Operations

Shasta-Keswick operations is about to enter a new phase of summer operations. Under the Bureau pf Reclamation’s planned operations, there will be larger volumes of exports from the Trinity River system through Whiskeytown Reservoir over the summer. There will also be larger release volumes from Keswick Reservoir to meet increasing downstream contractor demands (Figure 6).

Proposed Operations

The proposed CSPA Temperature Management Plan2 for June-October, 2021 would provide a lower Keswick Dam release. First, Trinity exports would end, except for releases of 300 cfs down Clear Creek, because Trinity water releases through Spring Creek Powerhouse are already pushing the threshold temperature of 53ºF. Second, Shasta release would be limited to releases from coldwater pool at 52ºF to provide 5000 cfs total Keswick release, thereby saving Shasta storage. Third, peaking power at Shasta Dam would be minimized to ensure that warm surface waters are not drawn into the TCD gates (Figure 7) during peaking operations.

Sustaining the cold-water pool in Shasta through the summer is a function of (1) maintaining total storage and cold-water-pool volume in storage: (2) reducing Whiskeytown releases when they become too warm (>53ºF); and (3) minimizing warm water from peak power releases. Such a strategy would help save winter-run salmon eggs in the summer spawning season.

Figure 1. Inflow (cfs) to Keswick Reservoir from Shasta Dam and Spring Creek Powerhouse (cfs), June 12-14, 2021.

Figure 2. Water temperature (ºF) of the water released from Shasta Dam, June 12-14, 2021.

Figure 3. Relationship between water temperature and Shasta Dam release volume, June 12-14, 2021.

Figure 4. Total reservoir release (cfs) from Whiskeytown Dam, June 12-14, 2021. Note that of the minimum 250 cfs release, about 125 cfs were released to Clear Creek to maintain base flows and were not releases through Spring Creek Powerhouse.

Figure 5. Water temperature of water exiting the Spring Creek Powerhouse into Keswick Reservoir, June 9-14, 2021.

Figure 6. Summary of Shasta operations, June 1-13, 2021. Note SAC is gage station 5 miles below Keswick Dam on Sacramento River. Source: https://www.usbr.gov/mp/cvo/vungvari/sactemprpt.pdf

Figure 7. Shasta Dam operations and reservoir storage conditions on June 10, 2021. Source: https://www.usbr.gov/mp/cvo/vungvari/sactemprpt.pdf .

  1. At other times, depending on specific conditions and operations, the opposite relationship is true.  See https://calsport.org/fisheriesblog/?p=3596, Figure 6, for example from 2014 when higher temperatures were associated with lower release volumes. ↩
  2. Referenced in https://calsport.org/fisheriesblog/?p=3714.  The May 23, 2021 CSPA Temperature Management Plan proposed limiting Trinity exports to 300 cfs for the entirety of the June-October period, to be released exclusively down Clear Creek.  In addition to the water temperature benefits in the Sacramento River, such operation would also conserve cold water and overall storage in Trinity Reservoir. ↩

The Week the Salmon Died

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It was the first week in June 2021. The salmon were the last of 2021’s endangered winter-run and threatened spring-run Chinook salmon heading up the Sacramento River to spawn below Shasta Dam and in tributary streams. Many were in the middle of their 300-plus-mile journey from the Golden Gate through the Bay, the Delta, the lower Sacramento River. Water temperatures rose to lethal levels through the lower end of the Sacramento River, as flows at Wilkins Slough (River Mile 125) dropped nearly 50% to 3500 cfs and water temperatures reached 25ºC (Figure 1).

Water temperatures above 68ºF (20ºC) are stressful for salmon, and 72ºF (22ºC) is their maximum tolerance limit that forces them to seek cold-water refuge. If salmon cannot find refuge, water temperatures near or above 77ºF (25ºC) are lethal.

On June 1, the State Water Board approved a “temporary urgency change petition” (TUCP) from the Bureau of Reclamation and the Department of Water Resources (DWR) to reduce Delta outflow. By June 2, less than half of the flow released in Redding to the upper reaches of the lower Sacramento River flow (about 8000 cfs, including 7000 cfs from dam releases) was reaching Wilkins Slough, 180 miles downstream. In those 180 miles, more than half the flow was diverted to agriculture. The high early-June water temperatures and low flows are unprecedented for late spring (Figure 2).

Reclamation and DWR’s petition discussed impacts to fish in the Delta. The water temperatures in the Sacramento River at Wilkins Slough in the first week in June show how the Delta and salmon far upstream are connected. The upstream impacts of bad Delta decisions is once again transparent: low requirements for Delta outflow means low flows and lethal water temperatures in the Sacramento River.

An extreme heat period for the Sacramento Valley is expected for the third week of June, and it is still only spring. Winter-run and spring-run adult salmon that made it to the spawning grounds below Shasta and Keswick dams earlier this winter and spring are very likely to experience highly stressful water temperatures (>60ºF) for holding and spawning. Because it is releasing too much agricultural water now, Reclamation is likely to run out of cold water in Shasta by the time that fall-run salmon arrive in Redding in October and November.

The drumbeat of dying salmon will be pounding all summer and into the fall.

Figure 1. Water temperature and Sacramento River flow at Wilkins Slough (RM 125) 5/25-6/7, 2021.

Figure 2. Water temperatures in the Sacramento River at Wilkins Slough (RM 125) in dry years of of the past decade. Values for 2021 are literally over the top. The lethal level for salmon is 77ºF. Stress occurs at >68ºF. Migration ceases at 72ºF.

Longfin Smelt 2021 – Another Poor Year

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The Bay-Delta longfin smelt population, listed as threatened under the California Endangered Species Act, is having another poor year because of the Bay-Delta habitat conditions in critically dry year 2021. Winter spawning and early rearing habitat conditions were poor due to low Delta outflow. Spring conditions have been similarly poor, with low Delta outflows and high water temperatures. Summer conditions will be even worse.

Winter

As in prior dry years, longfin spawned in the Delta in winter 2021. Their newly hatched pelagic larvae accumulated in the low salinity zone in eastern Suisun Bay close to Chipps Island near the city of Pittsburg (Figures 1 and 2). In wetter years, longfin larvae accumulate further west in western Suisun Bay and San Pablo Bay, and are also more likely to spawn in Bay tributaries, especially the Napa River. With Delta export pumps diverting about one-third of winter freshwater inflow to the Delta and Bay, significant numbers of larval longfin smelt were susceptible to being drawn into the central and south Delta, away from their low salinity zone nursery area in eastern Suisun Bay.

Spring

With low spring Delta outflows of 3000-6000 cfs, similar to critical drought years 2014 and 2015 (Figure 3), longfin juveniles were concentrated in the low salinity zone in the western Delta (Figure 4). In that location, they are more vulnerable to Delta exports than in the prior winter, and are also subjected to warmer water temperatures (Figure 5) detrimental to their survival (Jeffries et al. 2016).1

Summer

The prognosis for the summer is grim, given expected water temperatures over 68ºF under low flows allowed under the Temporary Urgency Change Petition (Figure 5).

Population Response

The combination of low outflow (poor habitat), vulnerability of larval and juvenile longfin smelt to export, and reduced numbers of adult spawners that have survived in recent years leads to low population recruitment (Figure 3).2

Summary and Conclusions

In a critically dry year like 2014, 2015, or 2021, Delta outflows should not fall below 6,000-8,000 cfs on a daily or tidally filtered basis (Figure 3). Such outflows keep the low salinity zone west of the Delta in Suisun Bay, where water would be cooler and longfin would be less likely to be drawn into the central and south Delta. State recovery planning for longfin smelt should also proceed as has been recommended.3

Figure 1. Catch distribution of larval longfin smelt in the mid-January 2021 larval fish survey. Red area is approximate location of low salinity zone. Red arrow is net direction of west Delta flow toward south Delta export pumps. Data Source: CDFW survey online report.

Figure 2. Catch distribution of larval longfin smelt in the February 2021 larval fish survey. Red area is approximate location of low salinity zone. Red arrow is net direction of west Delta flow toward south Delta export pumps. Data Source: CDFW survey online report.

Figure 3. Delta outflow in spring and early summer 2014, 2015, and 2021. Note the sharp decline in late May 2021 (blue line) following approval of Temporary Urgency Change Petition (TUCP).

Figure 4. Catch distribution of larval longfin smelt in the May 2021 20-mm fish survey #5. Red area is approximate location of low salinity zone (2-4 EC). Blue areas are higher salinity zones in Bay. Red line is approximate location of X2. Data Source: CDFW survey online report.

Figure 5. Longfin Recruits (Fall Midwater Trawl Index) vs Spawners (Index from two years prior) in Log10 scale by water year. The relationship is very strong and highly statistically significant. Adding Delta outflow in winter-spring as a factor makes the relationship even stronger. The 2019 brood year index was lower than expected, given the potential number of spawners (from the relatively high 2017 index) and 2019 having been a wet year. The 2020 index is as expected for a dry year, with low spawner numbers.

Shasta Trade-Offs – Summer 2021

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NEWS HEADLINES – All basically true.

  • California’s reservoirs face dangerously low levels
  • California faces worst drought in decades: ‘Economic disaster’
  • Restore the Delta, others file protest over Temporary Urgency Change Petitions for the SWP and CVP
  • 74% of California and 52% of the Western U.S. now in ‘exceptional’ drought
  • A ‘megadrought’ in California is expected to lead to water shortages for production of everything from avocados to almonds, and could cause prices to rise.
  • THE 2021 WESTERN DROUGHT: WHAT TO EXPECT AS CONDITIONS WORSEN
  • The Drought In The Western U.S. Is Getting Bad. Climate Change Is Making It Worse
  • TRULY AN EMERGENCY’: HOW DROUGHT RETURNED TO CALIFORNIA – AND WHAT LIES AHEAD
  • Endangered-Sacramento-River-winter-Chinook-salmon-are-dying-before-spawning-below-Keswick-Dam
  • Will California Save the Last Winter Run Salmon This Year?
  • Conservationists say time running out to save endangered salmon in Sacramento River

Where we stand now

Water Storage – Water levels of the major reservoirs of the Sacramento Valley are low and getting lower, even lower than critical drought years 2014 and 2015 (Figures 1-3).  Trinity Lake is slightly higher than 2014 and 2015 (Figure 4).

River Flows – Runoff from the Valley where the Sacramento River enters the Delta at Freeport has been lower than in 2014 or 2015 (Figure 5).  Sacramento River flow where it enters the Valley below Shasta Reservoir at Bend Bridge near Red Bluff was higher in April-May 2021 than 2014 or 2015 (Figure 6), reflecting higher 2021 demand for Shasta storage.

Delta Outflow – Delta outflow was at minimum levels of 4000-6000 cfs daily average in April-May 2021 to meet water quality standards for critical water years as in 2014 and 2015 (Figure 7).  That changed in early June, when the State Water Board approved a Temporary Urgent Change Petition, and Delta Outflow dropped to a roughly calculated 2000-3000 cfs.  Note total reservoir releases to Central Valley rivers at the beginning of June 2021 was approximately 18,000 cfs, and total water supply diversions was conservatively 15,000 cfs (83%).  Of these diversions, there were about 5000 cfs diverted from the Sacramento River and its tributaries, 5000 cfs from the San Joaquin River and its tributaries, 3000 cfs diverted within the Delta, and 2000 cfs diverted through the Delta export pumps.

Shasta Choices and Tradeoffs

As of June 1, 2021, the Bureau of Reclamation’s summer plan for Shasta-Trinity-Keswick operation is to release 7000-8000 cfs of Shasta and Trinity water from Keswick Reservoir to the ten-mile salmon spawning reach of the upper Sacramento River near Redding.  Target water temperatures are 56ºF for the Keswick release and 57ºF five miles downstream in Redding.  The flow and water temperature targets are met by mixing Shasta reservoir (~6000 cfs) and Trinity releases (1000-2000 cfs via the Spring Creek powerhouse) in Keswick Reservoir.  The Shasta release water temperature needs to be 54-56ºF to meet the Keswick release target temperature.  This depends on the temperature of the Trinity water delivered into Keswick Reservoir through the Spring Creek Powerhouse.  The water temperature of Spring Creek PH releases increases steadily over the summer, from 51-52ºF in early June to 56-57ºF later in summer.  The Shasta release temperature is controlled by selecting specific outlet gate operations in Shasta Dam (Figure 8).  The plan is to gradually use the Shasta cold-water pool through the summer via the pressure relief gates and to begin using side gates sometime in August as the reservoir (and cold-water-pool) volume and elevation drops.

The problem with this plan is that it leads to very poor survival (near zero) of winter-run salmon eggs in the ten-mile spawning reach downstream of Keswick Dam.  It also virtually dooms reproductive survival of spring-run and fall-run salmon in the fall.  The Keswick release needs to be less than 53ºF to ensure survival.  Midsummer side gate use is also unreliable, often leading to loss of access to the cold-water pool.

The Alternative Temperature Management Plan (CSPA TMP) that CSPA and two other groups submitted to the State Water Board on May 23, 2021, would provide much better water temperatures from June through October.  The CSPA TMP, comprised of a  transmittal letter, descriptive elements and spreadsheet, proposes a release of just 5000 cfs of 52-53ºF water from Shasta Dam’s gates and minimal warmer water inputs from the Trinity.  The CSPA TMP could provide a 5000 cfs release of 53-54ºF water from Keswick, with no side-gate deployment.  Reclamation could also modify daily peaking power production to limit withdrawals of warm water from the surface of Shasta reservoir.

The CSPA TMP would save the salmon and save approximately 200,000 acre-feet of Shasta storage and 200,000 acre-feet of Trinity storage.  After all, this is only the second year of drought.  Power production from five system powerhouses would also be significantly reduced, though power generation capacity would still be available for periods of extreme power demand.  Water supply deliveries would also be significantly reduced.  Water saved in storage would be available for future power production and water deliveries.  Therein are the trade-offs.

Summary and Conclusions

Saving the salmon is imperative because of the already poor state of salmon populations.  Two of these populations have long been listed under federal and state endangered species acts.  State and federal Laws and regulations require saving the salmon.  Cities and agriculture will still take most of the water, if not now, then later.

Figure 1. Water storage in acre-feet in Oroville Reservoir in 2014, 2015, and 2021.

Figure 2. Water storage in acre-feet in Folsom Reservoir in 2014, 2015, and 2021.

Figure 3. Water storage in acre-feet in Shasta Reservoir in 2014, 2015, and 2021.

Figure 4. Water storage in acre-feet in Trinity Reservoir in 2014, 2015, and 2021.

Figure 5. Sacramento River flow in cfs in 2014, 2015, and 2021, at the location where it leaves the Valley at Freeport near Sacramento. Note flow dropped to near 5000 cfs in early May and in June, 2021.

Figure 6. Sacramento River flow in cfs after April 1st in 2014, 2015, and 2021, at the location where it enters the Valley at Bend Bridge near Red Bluff. Note flow was higher in April and May, 2021, reflecting higher downstream demand for Shasta storage.

Figure 7. Delta outflow from the Central Valley May-July 2014, 2015, and 2021. Note sharp drop in Delta outflow at the end of May 2021, reflecting Temporary Urgent Change Petition.

Figure 8. Shasta Dam reservoir-release infrastructure, depicting operations at the beginning of June 2021. Note a combined 6000 cfs release with an overall temperature of 52-54ºF was achieved by releasing water from five upper gates and one PRG gate.