Category Archives: Bay-Delta

The Final Straw for Delta Smelt; Another Dagger for Longfin

Posted on by

Delta smelt and longfin smelt were not protected in the Delta in November-December 2019. High south Delta exports (Figure 1) and associated highly negative Old and Middle River (OMR) flows (Figure 2) pulled the spawning adult smelt toward the export pumps, likely significantly compromising what is left of the two populations. High exports and negative flows also pulled saltwater from the west Delta into the central Delta (Figures 3 and 4). This forced smelt to spawn further upstream in the fresher water of the central, east, and south Delta, sealing the fate of the numerous larval longfin smelt spawned there to the export pumps this winter. Young Chinook salmon, especially listed winter-run and spring-run entering the Delta in December, were also jeopardized.1

These circumstances were not allowed under the federal 2008 Delta smelt biological opinion (Figure 5) or the state’s longfin smelt incidental take permit (Figure 6). The new October 2019 Biological Opinion (BO) for the operation of the Central Valley Project (issued under the federal Endangered Species Act) does not preclude high exports or highly negative OMR flows. The pending new state Incidental Take Permit (ITP) for the operation of the State Water Project (to be issued under the California Endangered Species Act) follows the requirements of the federal BO for Delta smelt.

Given the December distribution of adult longfin smelt (Figure 7) and the likely distribution of the few remaining adult Delta smelt based on prior year surveys (Figure 8), the Smelt Working Group (SWG), Water Operations Management Team (WOMT), and the Director of the California Department of Fish and Wildlife (CDFW) should have limited south Delta exports in December. They did not.

The Trump administration’s new biological opinions simply do not protect these fish. The pending new state ITP for protection of these fish gives the Director of the California Department of Fish and Wildlife the last word in ordering changes to OMR flows. The CDFW Director’s non-decision in 2019 is a good indication of the level of protection that is likely under the new state ITP.

Figure 1. December 2019 state (HRO) and federal (TRP) south Delta exports. Note the maximum total rate of approximately 11,400 cfs was reached in the latter half of December.

Figure 2. December 2019 Old and Middle River (OMR) net daily flows.

Figure 3. Salinity (EC) in central Delta in December 2019.

Figure 4. Salinity (EC) in Old River in the south Delta in December 2019.

Figure 5. Page 281 of 2008 federal biological opinion for Delta smelt.

Figure 6. Page 10 of 2009 state Incidental Take Permit for longfin smelt.

Figure 7. Distribution of longfin smelt in December 2019 midwater trawl survey. These numbers are very low and show the present depressed level of the population.

Figure 8. Distribution of Delta smelt in December 2011 midwater trawl survey
showing likely distribution of remaining Delta smelt in 2019 (midwater trawl
survey found no Delta smelt in December 2019).

 

Central Valley Salmon Hatchery Release Strategies 2019 Some Good, Some Bad – Some Lessons Not Learned

Posted on by

Federal and State hatcheries released 32 million juvenile salmon into the Central Valley, the Bay-Delta, and nearby coastal waters in 2019.1 The hatchery programs included spawning and rearing salmon from all four salmon races: fall-run, late–fall-run, winter-run, and spring-run. The hatchery programs have come a long way through decades of adaptive management, but some lessons were not learned. In this post I summarize and discuss the release strategies in 2019 of the seven hatchery programs. In most cases, release strategies were good for smolt survival. Some releases were made into poor flows and high water temperature conditions that would contribute to poor survival from slowed migration, heat stress, starvation, or high predation rates.

Federal Coleman National Fish Hatchery on Battle Creek (Sacramento River)

The Coleman Hatchery released 11 million salmon to the Sacramento River and its major upper river tributary Battle Creek in 2019 (Figure 1). All but the 176,128 released to the Sacramento River near Redding were released at the hatchery into lower Battle Creek. All the fall-run were from brood year 2018 (spawned in fall 2018). The total late-fall-run release for brood year 2018 was 830,000 including 73,952 released in January 2019, with the remainder released in Nov-Dec 2018.

The Coleman hatchery continues to struggle with problems/conflicts associated with making releases too early or too late in the season.2 Early release of younger smaller pre-smolts has led to poor survival and return rates. Late releases can be a problem because of low flows and high water temperature in the lower Sacramento River (Figure 2). The early 2019 releases could have been made later in April, and the early May release could have been supported by a flow pulse from a near-full Shasta Reservoir in this near-record-high storage year.

Figure 1. Summary of Coleman NFH releases in 2019. Note 755,416 late-fall-run smolts from brood year 2018 were also released into Battle Creek in Nov-Dec 2018.

Figure 2. Spring 2019 river flow and water temperature in the lower Sacramento River at Wilkins Slough near Grimes. Red lines denote upstream releases of Coleman NFH fall-run smolts.

State Oroville Feather River Fish Hatchery

The Feather River Fish Hatchery released 9 million salmon smolts to the Feather River and the Bay in 2019 (Figure 3). All of the nearly 2 million spring-run were released into the lower Feather River in March and April. Six million fall-run smolts were released to the Bay. One million fall-run were released into the lower Feather.

Generally, all the smolts were released under favorable conditions. The release of fall-run into the lower Feather in early May occurred under marginal conditions (Figure 4). This late season fall-run smolt release into the Feather River was subject to potential high predation rates in the river and during their migration through the Delta.

The May releases of Feather River fall-run to east San Pablo Bay and the Napa River estuary (Mare Island) are problematic because that area is a major spawning and rearing area for longfin and Delta smelt during the period of releases, especially in wet years like 2019.3 Yearling or smolt-sized Chinook salmon are known to commonly feed on larval and juveniles fish in estuaries in winter and spring.

Figure 3. Summary of Feather River Hatchery releases in 2019.

Figure 4. Spring 2019 river flow and water temperature in the north Delta in the Sacramento River at Freeport.

State American River Nimbus Hatchery

The Nimbus Hatchery released 3.6 million fall-run salmon smolts to the American River and the Bay in 2019 (Figure 5). Approximately 2.2 million fall-run smolts were released to the Bay. Approximately 1.6 million fall-run were released into the lower American River (at Sunrise Boat Ramp).

Generally, all the smolts were released under favorable conditions. The lower American fall-run release in mid-May occurred under marginal conditions (Figure 4). This late season release into the American River was subject to potential high predation rates in the river and during their migration through the Delta.

The May and June releases to east San Pablo Bay (Conoco) and the Napa River estuary (Mare Island) are problematic because that area is a major spawning and rearing area for longfin and Delta smelt during the period of releases, especially in wet years like 2019.4 Yearling or smolt-sized Chinook salmon are known to commonly feed on larval and juveniles fish in estuaries in winter and spring. The early June releases to the Bay occurred under marginal conditions – high water temperatures stressful to young salmon (Figure 6).

Figure 5. Summary of American River River Hatchery releases in 2019.

Figure 6. Water temperature in spring 2019 at east end of San Pablo Bay near Mare Island release site of Nimbus Hatchery trucked fall run smolts.

State Mokelumne River Hatchery

The Mokelumne Hatchery released 6.6 million fall-run salmon smolts to the Mokelumne River, the west Delta, the Golden Gate, and the coast in 2019 (Figure 7). Approximately 4.5 million fall-run smolts were released to the west Delta near Sherman Island. Approximately 1.7 million smolts were released on the coast and near the Golden Gate5. The remainder (400,000) were released into the lower Mokelumne River.

Generally, most of the smolts were released under favorable conditions. One exception, the lower Mokelumne fall-run releases in mid–May, occurred under marginal conditions (Figure 4). This late-season release into the Mokelumne River was subject to potential high predation rates in the river and during their migration through the Delta. With the Delta Cross Channel closed, these lower river releases were further subject to potentially high risk conditions. In fact, no tagged smolts from the mid-May river releases were detected in south Delta salvage monitoring, an indication of poor survival within the Delta.

Another exception, the late-May releases to the west Delta, are problematic because they occurred under marginal survival conditions – subsequent high water temperatures stressful to young salmon in the west Delta and the Bay (Figures 6 and 8).

Figure 7. Summary of Mokelumne River Hatchery releases in 2019.

Figure 8. Water temperature in spring 2019 in Suisun Bay.

State Merced River Hatchery

The Merced Hatchery released 0.7 million fall-run salmon smolts to the west Delta near Sherman Island (Figure 9). Conditions were marginal in terms of water temperature for the May 1 releases (Figure 10).

Figure 9. Summary of Merced River Hatchery releases in 2019.

Figure 10. Water temperature in spring 2019 in west Delta in San Joaquin channel off Sherman Island at Jersey Point.

State San Joaquin Spring-Run Recovery Hatchery

The Salmon Conservation and Research Facility Hatchery near Fresno released 212,000 spring-run salmon smolts into the San Joaquin River in 2019 (Figure 11). Generally, most of the smolts were released under favorable conditions. The late release on May 30, however was problematic with river temperatures (Figure 12) and Bay-Delta temperatures (Figure 6, 8, and 10) being too high. The February releases were prone to being drawn into the south Delta and exposed to salvage through April (Figure 13). A similar problem occurred in 2018.6 Flow pulses or trucking/barging may help resolve this problem.

One very encouraging development was the return of 200 spring-run adults to the San Joaquin River near Fresno, including unmarked fish that were apparently born in the river (not hatchery-born) and successfully navigated the river from near Fresno out the Golden Gate.

Figure 11. Summary of San Joaquin River Hatchery releases in 2019.

Figure 12. Water temperature and flow in lower San Joaquin River at Vernalis in winter-spring 2019.

Figure 13. Spring-run hatchery smolt salvage at south Delta export facilities in 2019.

Federal Sacramento River Livingston-Stone Winter-Run Recovery Hatchery

The Livingston Stone Hatchery near Redding released 408,000 winter-run salmon smolts to the Sacramento River and Battle Creek in winter 2019 (Figure 14). Smolts were released under favorable conditions. Salvage of these smolts at south Delta export facilities (Figure 15) indicates some degree of risk probably from being diverted to the south Delta via Georgiana Slough.

Figure 14. Summary of Livingston-Stone Sacramento River Hatchery releases in 2019.

Figure 15. Salvage of hatchery winter-run sized smolts at south Delta export facilities in 2019. Collection includes some late-fall-run hatchery smolts from the Coleman Hatchery.

In Summary

Hatchery salmon releases in wet year 2019 were generally made under favorable survival conditions. However, some releases were made under unfavorable conditions that were avoidable either by altering release timing or location, or by providing pulsed flows to support smolt migrations. Note that it will be several years before we see the adult returns from these tagged hatchery smolts. However, based on past experience,7 the portion of fish that were released in 2019 under unfavorable conditions will likely have poor adult returns.

Fall X2 should extend through December

Posted on by

In a recent post, I described the Fall X2 provision in the 2008 Delta Smelt Biological Opinion that protects smelt by requiring a modest Delta outflow from mid-August through October in Above Normal and Wet years.  In the same post, I described how the 2019 Biological Opinion for smelt would move the compliance point for Fall X2 upstream into the Delta, reducing low salinity zone habitat.   In this post, I suggest that the Fall X2 requirement should not only be retained with the old compliance point, but also that the applicable time period should extend through December.

First, if the X2 provision is not extended into December, this is what happens:  (1) Delta outflow drops to zero or even negative, as occurred this past November 2019 (Figure 1); and (2) the low salinity zone moves up into the Delta via the San Joaquin River channel toward the export pumps (Figure 2).

Second, winter-run salmon smolts that pour into the Delta from the Sacramento River in November and December of all but the driest years (Figure 3) will have difficulty surviving and exiting the Delta for the Bay and ocean.

Third, what few Delta smelt that may be surviving will be put at risk of being drawn into the central and south Delta (Figures 4 and 5).

Fourth, longfin smelt will be at risk to being drawn into the Delta (Figures 6 and 7).

Fifth, the primary food of young Delta native fishes, calanoid copepod adults, which concentrate in the low salinity zone, would be drawn into Delta (Figure 8).  Bay-Delta pelagic plankton productivity would suffer.

In conclusion, there are presently few constraints on water project operations in the Delta in November-December.  Freshwater outflow to the Bay can be zero or even negative, as occurred this past month, November 2019.  The updates to the Bay-Delta Water Quality Control Plan and to state permits that regulate Delta exports should extend Fall X2 through December in order to protect Delta native fishes.  Compliance would entail Delta outflows in the 8000-10,000 cfs range and/or Jersey Point salinity of about 500 EC.

Figure 1. Tidally filtered flow in the Sacramento River channel at Rio Vista and Jersey Point in the San Joaquin channel in November 2019.

Figure 2. Salinity (EC) at Jersey Point in the San Joaquin channel of the west Delta in November 2019.

Figure 3. Cumulative catch of winter-run Chinook salmon at Knights Landing rotary screw traps in fall-winter of water year 2017. Source: DOSS 2017.

Figure 4. Trawl catch distribution of Delta smelt fall 2011, the last time Delta smelt were relatively common.

Figure 5. Salvage of Delta smelt pre-spawn adults in fall-winter of water year 2003.

Figure 6. Longfin smelt trawl catch distribution in November 2011.

Figure 7. Longfin smelt trawl catch distribution in December 2011.

Figure 8. Adult calanoid copepod catch distribution in November 2011 zooplankton survey.

Analyzing Fish Population Dynamics in the Bay-Delta

Posted on by

I have been analyzing the declines in Bay-Delta and Central Valley fish populations for over 40 years. Fish population dynamics were the focus of my college education and my 50-year career in environmental impact assessment. I have participated in all the major efforts to understand the Bay-Delta fish population declines. From all of these efforts, it is clear to me what has caused the major fish population crashes.

Pre-1970

First and foremost are the well known historic factors, the original sins pre-1970s of diverting water, building levees and dams, urban development, gold mining, cutting forests, polluting rivers, over-fishing, and introducing non-native species. These explain many of the major native fish population declines and extinctions such as the Sacramento perch and San Joaquin spring-run Chinook salmon, and the near extinctions of Delta smelt, green sturgeon, winter-run and spring-run salmon, and steelhead.

Post-1970

Since 1970, there have been dramatic declines in salmon, steelhead, smelt, sturgeon, splittail, and striped bass, often described as “recruitment failure” or failure to reproduce. While some of the blame most certainly is on continuing effects of the aforementioned original sins, the major post-1970 shifts were the consequence of a new array of stresses that hit the whole fish community, especially native fish populations. Most certainly the droughts of 76-77, 87-92, 01-02, 07-09, and 12-15 were a major underlying factor; however, it was the man-made responses to the droughts that caused most of the damage. Asian clam and other non-native aquatic invertebrate invasions to the Bay-Delta in the 80s were another stress, in part brought on by the aforementioned factors. Poor water management response to these new threats has caused further damage. The big culprits of change were the water management stresses described below.

1. State Water Project

The addition of the State Water Project (SWP) in the mid-1970s nearly tripled Delta export capacity (4400 to 11,400 cfs pumping rate1) and annual exports (2 million acre-feet to 6 million acre-feet annual exports). The additional Delta exports had huge fish population effects in the mid-70s from salvage mortality and entrainment of young fishes, as well as on fish habitat conditions in the rivers, Delta, and Bay. These stresses resulted in major population declines, which in turn resulted in the imposition of export restrictions in new water quality standards in 1978 (D-1485), and eventually to species listings under the Endangered Species Act in the 1990s.

2. Reservoir Operations

The increase in exports changed reservoir operations, including within-year reservoir release strategies and long-term multiyear reservoir storage patterns. Reservoir storage was depleted faster in droughts because of higher water supply demands. These effects continue today.

3. Water Supply Demands

Ever-increasing water supply demands from agricultural and municipal users have reduced river flows, Delta outflow, and reservoir storage. It’s not only the Delta’s 6 million acre-feet of exports, but the more than 20 million acre-feet from other Central Valley water diversions.

4. Invasive Species

Invasions of non-native clams, shrimp, fish, and zooplankton species since the 1970s have occurred in-part due to changes in Bay-Delta hydrology and water quality, as well as physical and biological habitat conditions. Delta pelagic (open water) habitat is now dominated by low-productivity reservoir water. The low salinity or mixing zone of the estuary became far less productive because of species invasions and reservoir water moving through to the south Delta export facilities, taking productive low-salinity habitat with it. The Delta is warmer from higher warm river inflows from spring through fall to feed water project exports, further favoring non-native warm-water fishes. Turbidity is lower, favoring non-natives. Invasive aquatic vegetation benefits from low turbidity, and the vegetation further favors non-native fishes over native fishes.

Post-1990

Since 1990, there have been steps backward that have undermined effective strategies and actions that had been undertaken beginning in the late 1970s to help depressed fish populations. Below are five examples in a long list of actions/changes.

1. Changes to D-1485

Beginning In 1978, Delta water quality standards in Decision 1485 placed restrictions on Delta exports, improved Delta outflows, and set salinity standards that had benefits for native fishes. Beginning in the 1990s, these post-1970 constraints on water diversions were changed, ignored, or eliminated. For example, new standards in D-1641 (1995 Accord) dropped the D-1485 June-July export restrictions.

2. Eliminating VAMP Export Restrictions and Higher Outflow Requirements in April and May

The Vernalis Adaptive Management Plan (VAMP) from 2000-2009, and its operational precursors under the CVPIA (1991) and the 1995 Accord, sought to protect Central Valley salmon and Delta native fishes by reducing April-May Delta exports and increasing spring Delta inflows and outflows. During the VAMP years, exports were restricted to less than 2000 cfs in April-May to protect fish (Figure 1). In the post-VAMP decade, restrictions were lifted and exports increased, especially in post-drought recovery wet years 2011 and 2017 (Figure 2).

3. Temporary Urgency Change Petitions (TUCPs) and Orders

Temporary urgency change orders during the recent drought allowed April-May Delta outflow to fall to around 5000 cfs in 2014 and 2015, from the normal near-10,000 cfs lower limit (Figure 3). Such low outflows in combination with Delta exports are devastating to Delta native fishes and Central Valley salmon and steelhead.

4. Delta Channel Barriers

The operation of the Delta Cross Channel, Head of Old River, South Delta, and False River barriers helps to keep export salinity down by funneling the fresher Sacramento River water to the south Delta export pumps. This increases the efficiency of exports in taking reservoir water in drier years and seasons. With the exception of the Head of Old River, barrier operation also funnels Delta native fish production (pelagic eggs and juveniles) and migrating young salmon (and their low salinity habitat and food sources) directly to the export pumps instead of to the Bay.

5. Suisun Marsh Salinity Control Gates

Since the installation of the Suisun Marsh Salinity Control Gates (SMSCG) in Montezuma Slough in 1989, the Slough and Marsh no longer function as critical low salinity habitat in drier years and seasons. Without high freshwater inflow, the Slough and Marsh no longer maintain the high biological production the once contributed to the Bay. The following excerpt from a DWR 2019 blog post inadvertently describes how limited the benefits of Suisun Marsh have become in the absence of flow:

DWR launched a pilot project last year that directed more fresh water flow into Suisun Marsh. The action involved opening salinity control gates in the summer months instead of during fall and winter, as is customarily done to reduce salinity in the marsh for migrating ducks and other waterfowl. The Delta smelt relies on low-salinity water – opening the salinity control gates allowed the smelt to enter the marsh from the Sacramento River, where it can access greater amounts of food and shelter.

Extinction looms so closely over the Delta smelt population that the project could have been considered a success even if it didn’t lure any countable Delta smelt to the marsh, said DWR Lead Scientist Ted Sommer. Just creating the conditions that allow smelt to thrive – that is, low salinity levels, lots of food, and high turbidity or muddy water that magnetizes smelt – would have been a cause for celebration.

Conclusion

There are many, many other examples of adverse changes that have put fish population dynamics in the Delta in a perpetual downward spiral. Since 1970, almost of all them involve reduction of Delta inflow and outflow, elimination of measures to mitigate the effects of reduced Delta inflow and outflow, and/or the biological response to reduced Delta inflow and outflow.

Figure 1. State south Delta exports (Harvey Banks pumping plant) in spring 1997-2010.

Figure 2. State south Delta exports (Harvey Banks pumping plant) in spring 2011-2019.

Figure 3. Delta outflow April-May 2007-2009 and 2013-2015 droughts.

 

 

 

  1. Initially exports were even higher with the new 11,000 cfs export capacity of the State Water Project. Total exports reached 12,000-14,000 cfs ↩

Reclamation’s Proposed Delta Smelt Fall Habitat Action In 2019

Posted on by

The US Bureau of Reclamation (Reclamation) is proposing a “Delta Smelt Fall Habitat Action” that would eliminate the requirement to increase outflow from the Delta in the late summer of this wet water year.1 The “Fall X2” flow increase that Reclamation has placed on the chopping block is a major provision in the 2008 Delta smelt biological opinion (BiOp). Reclamation describes the substitute proposed Action in a summary its webpage:

The Proposed Fall Habitat Action (Proposed Action) for Delta Smelt habitat in Water Year (WY) 2019 will achieve the Action 4 objective. Action 4 of the 2008 BO requires adaptive management to ensure that the implementation addresses the uncertainties about the efficiency of the action. Action 4 also states that as new information is developed and as circumstances warrant, changes by the Service to the Fall X2 action itself may be necessary. The Proposed Action is a plan to adaptively manage and modify its operation of the CVP/SWP under RPA Action 4.2

In brief, the “circumstances” that “warrant” this “adaptive management” are that getting rid of Fall X2 will allow Reclamation to export more water from the Delta this fall.

In August 2019, Reclamation issued an Environmental Assessment (EA) of the Proposed Fall Habitat Action. Though the Action will unravel a major component of the 2008 Biological Opinion for smelt, the comment period was 15 days. CSPA submitted comments; some of them are restated below, in response to citations from the “Effects Analysis,”3 an appendix to the Environmental Assessment.

The Effects Analysis quotes the BiOp to portray the Proposed Action as a scientific investigation, stating:

“[T]here is a high degree of uncertainty about the quantitative relationship between the size of the Action described above and the expected increment in Delta Smelt recruitment or production.” (p. 1).

Comment: After 2011, it has been nearly impossible to measure population response to changes in management because the smelt population has become so low. Likewise, a negative response cannot be detected at the present population level. The only certainty to be gained from harming a nearly extinct population even more is that Reclamation will increase exports from the south Delta.

The Effects Analysis selectively calls out results of the first implementation of the Fall X2 requirement in 2011:

“Abiotic habitat did increase in 2011 as predicted from the AMP, but other variables such as zooplankton abundance were too variable to draw a conclusion, and Delta Smelt growth rate comparisons remain incomplete as of 2019.”  (p.2)

Comment:  Following implementation of Fall X2 flows, smelt abundance increased sharply in the fall 2011 index. A quick look at zooplankton 2011 vs 2010 (Figure 1) also indicates an increase in zooplankton (key smelt food source) in Suisun Bay/Marsh in 2011.

Figure 1. Zooplankton (key Delta smelt food source) in September 2011 and 2010.
Note increased abundance downstream in 2011.

The Effects Analysis tries to explain the lack of response of Delta smelt to the 2017 Fall X2 action as a function of water temperature, concluding that the action was just futile:

In 2017, a Fall X2 adaptive management action was implemented. The results of the 2017 monitoring program were evaluated in the IEP’s 2019 draft FLOAT-MAST, which concluded that summer water temperatures were a major factor in the condition of Delta Smelt in 2017, stating at p.102: Given the long periods in July and August >22C we are confident that water temperature had a major negative effect on Delta Smelt in 2017 and is likely a primary factor in the lack of response of the Delta Smelt population to the high flows.  And at p. 104: Dynamic biotic components were somewhat better in 2017; however, the lack of response of the Delta Smelt population suggests that any benefits of changes in the habitat were minimal. (p. 3)

Comment:  It is true that recruitment of Delta smelt in 2017 was exceptionally low, despite the Fall X2 action.  This is because the number of adult spawners in 2017 was at a record low (Figure 2).

Fall 2017 water temperatures were slightly higher in the west Delta at Jersey Point compared to 2011 (Figure 3).  However, fall 2017 water temperatures were not unusually high compared to fall 2011 for Freeport or for Rio Vista in the Sacramento River channel of the Delta (Figure 4).  June and July Sacramento River water temperatures were substantially higher in 2017 than in 2011, because June and July Sacramento River flows were much lower in 2017 compared to 2011 (Figure 5). 

In general, spring habitat conditions were poorer in 2017 than in 2011:  2017 had lower spring Delta outflows (Figure 6) and much higher south Delta exports (Figure 7).

In sum, the 2017 fall index for Delta smelt was unusually poor because of poor conditions for Delta smelt in the spring and summer.  However, the response of longfin smelt to the implementation of Fall X2 in 2017 had a better outcome (Figure 8).  Despite poor number of spawners, the 2017 recruitment of longfin smelt per spawner was high. 

These data undermine Reclamation’s conclusion that the 2017 Fall X2 action had no benefit. 

Figure 2. Log vs Log plot of fall FMWT Index of Delta smelt (recruits) vs previous fall index (spawners). Blue years are wet years. Red years are dry and critical water years. Year types are determined by the California Department of Water Resources for the Sacramento River runoff to the Bay-Delta Estuary (http://cdec.water.ca.gov/cgi-progs/iodir/WSIHIST).

Figure 3. Comparison of Jersey Pt habitat conditions in 2017 versus 2011. Tidally filtered flow data were not available for 2011.

Figure 3. Comparison of Jersey Pt habitat conditions in 2017 versus 2011. Tidally filtered flow data were not available for 2011.

Figure 4. Freeport and Rio Vista water temperatures 2013-2019.

Figure 5. Freeport flow and water temperature summer 2011 and 2017.

Figure 6. Summer Delta outflows in 2011 and 2017.

Figure 7. South Delta federal exports (TRP) and state exports (HRO) in 2011 and 2017.

Figure 8. Longfin smelt spawner-recruit relationship, with improved recruitment in 2011 and 2017. Wet year blue, dry year red. Source: http://calsport.org/fisheriesblog/?p=2513

So, after stating inaccurate and misleading reasons why the Fall X2 action is not effective, the Effects Analysis offers inaccurate and misleading reasons why not implementing Fall X2 and instead fussing with the Suisun Marsh Salinity Control Gates (SMSCG) will be a positive switch.

“Forecast of salinity conditions in the Delta indicate that operating to an X2 of 80 km along with SMSCG operations in September and October would result in suitable salinity conditions (< 11,000 uS/cm) in the western Delta including Suisun Marsh, Grizzly Bay, and Honker Bay during these two months.”  (p. 17)

Comment:  Operating the SMSCG tide gates, while not implementing Fall X2, will push more Delta outflow into Suisun Marsh, with less outflow reaching eastern Suisun Bay.  Both actions would potentially negatively affect Delta smelt compared to implementing the Fall X2 Action per the existing BiOp.

“However, as explained above, this estimate of abiotic habitat index does not account for the habitat created in Suisun Marsh through the operation of the SMSGC, which would increase the index.” (p. 31)

Comment:  moving outflow through SMSGC reduces habitat in eastern Suisun Bay, and subsequently traps any Delta smelt in Suisun Marsh once the gates are again closed.

Conclusion:  Stock-recruitment models show a strong positive population response for Delta smelt in 2011 (see Figure 2) and longfin smelt in 2017 (see Figure 8).  The strong population responses in 2011 and 2017 offer a strong case for implementing the Fall X2 action in 2019.  Reclamation’s only justification for eliminating the Fall X2 action in 2019 is to increase water available for export.  Biology has nothing to do with it.