More on Fall X2 Adaptive Management

In an October 11 post, I discussed the state of California’s decision to maintain fall Delta outflow to the Bay (Fall X2). The 2008 Delta Smelt Biological Opinion (BO) requires that the State Water Project and the Central Valley Project keep the low salinity zone (X2) at km 74, near Chipps Island, in the fall of wet years. In early October, 2017, Reclamation and DWR requested that the fisheries agencies waive this wet year requirement to allow greater south Delta exports. The US Fish and Wildlife Service approved. But several days later, the California Department of Fish and Wildlife found that the action did not comply with the California Endangered Species Act, and the California Department of Water Resources reduced its south Delta exports to maintain Fall X2 compliance.1

To help the state maintain compliance, Reclamation began weekday closings of the Delta Cross Channel (DCC) (Figure 1), opening the DCC only on weekends to facilitate boat travel (Figure 2). Closure of the DCC forces more of the Sacramento River flow down the north Delta channel (Figures 3 and 4) repelling salt intrusion in eastern Suisun Bay near Collinsville (km 81) (Figure 5). The closure occurred 10 to 12 weeks earlier than normal (usually December 15), a highly unusual and provocative manipulation of Delta hydrodynamics. Its continued application after November 1 changes the hydrodynamic effects. Now that the Fall X2 requirement has expired, Delta outflow is lower and exports are higher. Under these conditions, DCC closure contributes to greater salinity intrusion into the central Delta via the lower San Joaquin channel and False River, moving Low Salinity Zone and Delta smelt back toward the central Delta.

DCC closure also helps more Mokelumne River adult salmon better hone in on their home river by keeping Mokelumne water out of the Sacramento channel near and below the DCC.2 However, Sacramento River salmon that enter the Mokelumne forks when the DCC is open on weekends would be blocked and delayed when the DCC is closed during the week. Closing the DCC also reduces San Joaquin channel net freshwater flows (Figure 6), which may hinder migrations of Sacramento, Mokelumne, and San Joaquin river adult salmon migrating up the San Joaquin channel of the Delta.

A likely upside of this unusual manipulation of cross-Delta freshwater flow is that it serves to keep the Sacramento River channel of the Delta fresher, which is part of the intent of the Fall X2 requirement. This action has minimal cost to reservoir storage and Delta exports, and it reduces straying of returning Mokelumne River hatchery salmon. On the downside, these DCC operations disrupt Delta hydrodynamics and water quality, move the Low Salinity Zone into the central Delta threatening Delta smelt survival, and interrupt salmon migrations in the Sacramento and San Joaquin rivers. It is likely that the Delta’s adaptive managers neither monitored nor assessed these potential downside ramifications.

Figure 1. Location of Delta Cross Channel in north Delta. (Base map from CDEC)

Figure 2. Reclamation began weekday closure of the Delta Cross Channel in mid-September (flow values are 0 on seven day intervals).

Figure 3. Weekday closure of the Delta Cross Channel in mid-September increased net flow downstream of the DCC in the Sacramento River channel below Georgina Slough.

Figure 4. Weekday closure of the Delta Cross Channel in mid-September increased net flow downstream of the DCC in the Sacramento River channel at Rio Vista.

Figure 5. Weekly closures of the Delta Cross Channel helped to maintain Fall X2 below Collinsville (km 81) through October in 2017.

Figure 6. Sporadic closure of the Delta Cross Channel reduces net freshwater flow in the lower San Joaquin channel in the central and western Delta.

Further Thoughts on the California WaterFix

The Metropolitan Water District of Southern California, commonly known as MWD, recently released a series of information papers on the California WaterFix (Delta Tunnels).  In this post, I further address MWD’s “assessment” of what will happen to the Bay-Delta environment and fish community if the WaterFix is built and operated.  Excerpts from MWD’s papers and my comments follow.

WaterFix Objectives

California WaterFix proposes a strong operations plan based on sound, collaborative science and adaptive management to meet the following objectives:

  • Improve water supply reliability
  • Enhance ecosystem fishery habitat throughout the Delta
  • Allow flexible pumping operations in a dynamic fishery environment
  • Improve export water quality
  • Respond to climate change risks
  • Reduce seismic risks

Comment:  The proposed plan is unsound, not science-based, with no operations or adaptive management plan.  The WaterFix will wreak havoc on the Central Valley, Bay-Delta ecosystem.  That havoc will further water wars, not reliability.  Fishery habitat that depends on freshwater input will get less of it.  This will make the Bay-Delta warmer, saltier, more polluted, and more subject to the rigors of climate change.  Southern California will take the fresh clean Sierra water, leaving behind new burdens on the Bay-Delta.

Record Exports

State Water Project and Central Valley Project operations have been, and continue to be, affected by regulations that seek to change flow regimes in the Delta by setting rules for outflow variables. This has decreased operational flexibility and reduced exports to 25 million Californians who receive water from the SWP and CVP south of the Delta and millions of acres of irrigated farmland.

Comment:  Woe be it to saving some water for the rivers, Delta, and Bay.  Exports have increased each decade since the 60’s, when the SWP was built.  Delta export records were set in the 2000’s, reaching above 6 million acre-feet, only to be further eclipsed in 2011 and nearly so in 2017.  Relaxed outflow and salinity regulations in the 2012-2015 drought decimated fisheries and brought salt levels to the Delta not seen in four decades.  Such low flow and higher salinity conditions would be the new norm under the WaterFix.

Protecting Flows in the Delta

A more natural flow direction in the Delta during critical fish protection periods will increase water supply reliability and minimize reverse flows. North Delta diversions, fish screen designs, bypass flow criteria and real time operations will be managed to limit effects on listed fish species.

Comment:  Flow direction will not change – continued South Delta exports will still cause negative Old and Middle River, Jersey Point, False River, Threemile Slough, and Prisoners Point flows, but with less inflow from the North Delta.  There are no non-critical fish protection periods.  Adding more diversion will not protect fish.  The new North Delta fish screens will not protect fish1.  Bypass flow criteria will not repel salt or protect young fish from increasing diversions and greater tidal reverse flows when they migrate through the Delta.  Real-time operations have been around for a long time, and while they have protected water supply quantity and quality, they rarely have protected fish.

New Fish Habitat Benefits

Some of the benefits of the fishery habitat that will be created and restored include:

  • Improved habitat conditions along important juvenile salmon migration routes
  • Restored tidal and non-tidal wetlands, and native riparian forest habitat
  • Increased food production, spawning and rearing areas
  • Natural refuge from predators and changing climate conditions
  • Improved connectivity between existing areas of natural habitat

Comment:  The only changes in habitat that were not already required and planned are (1) the over two miles of perforated steel walls along the banks of the Sacramento River in the North Delta, and (2) the considerable reductions in freshwater flow into the Delta and Bay.  Most of the habitat improvements in the now defunct Bay Delta Conservation Plan or BDCP are not included in the WaterFix.

Changes in Delta Export Regulations

The SWP and CVP facilities have long been impacted by changing regulations governing both projects’ diversion facilities in the south Delta. On average, D-1641 has reduced SWP and CVP diversions and increased Delta outflows to the San Francisco Bay by about 300,000 acre-feet a year as compared to the SWRCB’s prior requirements.

Comment:  Since D-1641 rules came online in the mid-1990’s, exports have continually increased, including record levels above 6 maf in 2005, 2006, 2011, and 2017.  Water year 2012, a below-normal water year, was not far behind at 5.8 maf.  Even below-normal 2010, after three critical water years, saw 4.8 maf of exports, equivalent to wet year exports in 1998 and 1999.  Yes, exports were down in the 2007-2009 and 2013-2015 droughts, but were not unlike the 1977 and 1990-1992 drought levels.

Compounding the impacts, the biological opinions have decreased diversions and increased outflows by about another 1 MAF a year (Source: MBK Engineers and HDR “Retrospective Analysis of Changed Central Valley Project and State Water Project Conditions Due to Changes in Delta Regulations,” January 2013). 

Comment:  If this were the case, how is it that a record 6.7 maf of Delta exports in wet year 2011, and 5.8 maf in below-normal 2012 were possible under the 2008-2009 biological opinions?  The new restrictions, though real on paper, did not restrict actual exports, only the future capacity of exports.  The WaterFix plan would eliminate such constraints on total exports.  Though MWD, DWR and the Bureau of Reclamation say they would not increase exports, can we really take them at their word with WaterFix’s 40% increase in export capacity?

The increased Delta requirements and export constraints have further affected SWP and CVP operations by decreasing operational flexibility and increasing water supply vulnerabilities during dry conditions. This, in turn, reduces project reservoir storage, water deliveries, and supply reliability. Figure 1 illustrates the decrease in average SWP and CVP delivery capability over time due to additional regulatory requirements. As shown in the figure, over a period of a little more than 25 years, the export capability of the two projects has been reduced by over 3 MAF per year. California WaterFix is intended to reverse this downward trend.

Comment:  Again, real exports have increased year after year as new capacities south-of-Delta have come online.  Reservoir storage has been more aggressively used to the detriment of long-term water supply.  Restrictions applied have done more to deter future exports; thus the need for the WaterFix.

North Delta diversions, fish screen designs, bypass flow criteria and real time operations will be managed to limit effects on listed fish species.

Comment:  The permitting agencies have set low, unattainable, and arbitrary limits on effects (e.g., 5% loss of fish passing north Delta intake screens).  They contend that all the Valley flow and export “valves/knobs” and infrastructure operational options (e.g., gate opening/closure, air bubble screens, etc.) can be “managed” to protect listed fish.  Even if that were possible, this does not account for all the unlisted fish including striped bass, American shad, splittail, lamprey, threadfin shad, fall run salmon, native minnows, and pelagic habitat.

Adaptive Management

An Adaptive Management Program would be implemented through a collaborative process with regulatory agencies, project operators, and water contractors. This would provide a structured science process to develop adaptive means of improving conditions for both the ecosystem and water supply. Project operations that respond to real-time Delta conditions would also advance these objectives and provide greater certainty for water deliveries.

Comment:  The foxes, wolves, and hawks will be there to ensure a continuous supply of chickens from the henhouse.  Past adaptive management has focused on protecting water deliveries.

Biological Opinions

These biological opinions determined that California WaterFix as proposed would neither jeopardize the continued existence of species listed under the federal Endangered Species Act (ESA) nor destroy or adversely modify critical habitat for those species.

Comment:  What happened between the draft and final Opinions?  The agencies responsible for the application of federal and state Endangered Species Acts have taken out their false teeth and set them on that beautiful nightstand called adaptive management.

Exporting Water from North Delta

Over a period of a little more than 25 years, the export capability of the two projects has been reduced by over 3 MAF per year. California WaterFix is intended to reverse this downward trend.

Comment:  Again, export records have been achieved in all water year types in the decades of the 2000’s.  Yes, D-1641 water quality standards, listed fish biological opinions, and operation permits have placed new rules on “capability” but have done little to appease the appetite for water that the two projects have no right to.  Now they want new rights to further wet their thirst.

Comment:  This figure shows a commitment to constraint (subject to change under “adaptive management”) at the proposed north Delta diversion.  What it does not show is the ability to increase north Delta exports by increasing reservoir releases or the ability to export water from the south Delta.

Operating Rules

The initial operating criteria for California WaterFix includes regulatory requirements that were established through D-1641, the 2008 and 2009 biological opinions for existing water project operations, and new criteria developed through California WaterFix’s environmental permitting process.

Existing regulatory requirements in the assumed initial operating criteria include:

  • Salinity standards;
  • Spring and fall outflow to manage the overall salinity gradient (known as “X2”);
  • Cross Channel Gate, Suisun Marsh Gate, and temporary agricultural barrier operations;
  • Limits on SWP and CVP diversions to manage flows in Old and Middle Rivers and entrainment;
  • Rio Vista flow.

New regulatory requirements in the assumed initial operation include additional limits on SWP and CVP diversions (i.e., Old and Middle River flow reversals) and flow (i.e., spring outflow, North Delta Diversion Bypass flow). California WaterFix also includes a permanent operable gate at the Head of Old River for fish migration protection and criteria for its operation.

Comment:  All of these rules have been weakened in recent years to maintain water diversions.  All the “rules” for the existing projects operations are in the process of review and face possible change because the ecosystem and listed fish have not been adequately protected.  The proponents of WaterFix have not proposed or evaluated new rules for existing infrastructure and operations or for new infrastructure and operations if WaterFix were constructed.

Water Transfers

The flexibility provided by California WaterFix also improves the capability of moving water transfer supplies across the Delta. The increased conveyance and operational flexibility would significantly increase the amount of available capacity to accommodate the movement of water transfers across the Delta and the SWP and CVP system.

Comment:  Water transfers have significant potential impacts.  Existing constraints would be removed.

Water Quality Standards

The variable split between north and south diversions would allow a flexible and improved approach toward compliance with flow and salinity standards. For example, if salinity increased on the lower Sacramento River, the SWP and CVP could opt to increase diversions in the south Delta and thereby allow greater flow down the lower Sacramento River. In contrast, if salinity increased on the lower San Joaquin River, the SWP and CVP could decrease water diverted in the south Delta and increase diversions in the north Delta, thereby increasing flow in the lower San Joaquin River and south Delta. The flexibility offered by this example would limit reverse flows in the central Delta near Jersey Point, which in the past have drawn saltier water from the San Francisco Bay into the central Delta.

Comment:  None of these assumptions are true.  Lower Sacramento River flows are affected by south Delta diversions.  North Delta diversions would affect Jersey Point reverse flows on the lower San Joaquin River because less water would pass through Georgiana Slough and the Delta Cross Channel. The Delta Outflow Index would remain the same whatever the split.

With California WaterFix, the SWP and CVP would continue to meet existing Delta water quality, fishery objectives, and any future regulatory requirements. Increased diversion flexibility afforded through the approval of California WaterFix would only enhance the capabilities of SWP and CVP projects to meet existing Bay-Delta requirements. Because California WaterFix can take advantage of opportunities to divert and store wet-period storm flows and allow for south Delta diversions in drier periods, in-Delta water quality can be better managed. As a result, the proposed California WaterFix operations would continue to be as protective, if not more, of existing beneficial uses.

Comment:  How does MWD know what future requirements will be, let alone whether the Projects can  meet them or the water supply cost of meeting them?  Allowing continued south Delta exports in dry periods has been the heart of Bay-Delta problems for many decades.  Most wet-period storm flow is stored in Valley reservoirs; that remaining has been allocated for the Bay.  There are no proposed changes in infrastructure or operations that would make WaterFix more protective of existing beneficial uses.

Delta Smelt Population Dynamics


The population dynamics of the San Francisco Bay-Delta estuary’s endangered Delta smelt can be viewed using patterns in annual indices of their abundance published by the California Department of Fish and Wildlife (CDFW). Indices of abundance are available from the Fall Midwater Trawl and Summer Townet surveys over the past five decades. Since Delta smelt have a short one to two year lifespan, they readily lend themselves to spawner-recruitment (S/R) analyses that help define the population dynamics of the species.

This report employs S/R analyses to review long-term trends in the population indices of the Delta smelt. The analyses support the hypotheses that abundance (adult numbers) and recruitment into the adult population are primarily controlled by the numbers of adult spawners, adjusted by wet-dry year differences in production of juveniles. In other words, the population abundance from year to year is determined by the number of eggs laid each year and the survival of each egg cohort to adults a year later.

Annual Indices of Delta Smelt Abundance and Recruitment

The long-term trends in Delta smelt reflected in the CDFW annual indices of summer and fall survey catch show dramatic declines over the past five decades (Figures 1 and 2). In the Summer Townet (STN) Index (Figure 1), the most obvious population declines are in the early 1980’s and the mid-2000’s. The Fall Midwater Trawl (FMWT) Index (Figure 2) highlights several key periods of population change: 80-83, 88-91, 00-05, and 09-13.

Figure 1. Delta smelt Summer Townet Index (1959-2016). Data source: CDFW

Figure 2. Delta smelt Fall Midwater Trawl Index (1967-2016). Source: CDFW

Spawner-Recruit Analyses

In this report I break down these indices by depicting three relationships: fall adults to the following summer recruits, summer recruits to following fall adults, and fall adults to following fall adults.

The relationship between the fall index of adult spawners to the index of juveniles the following summer is shown in Figure 3. Note the strong positive and highly significant relationship between the numbers of fall adult spawners and the numbers of juveniles that survive to the following summer. This relationship is indicative of the strong role the number of adult spawners (egg production) has on recruitment into the population. Note also the generally lower recruitment-per-spawner in drier years (red years), which is likely the result of a complex of factors related to Delta inflow/outflow and the export of water from the Delta. The population tends to expand (up to 10-fold, one log10 level) with the higher recruitment-per-spawner in wet years and tends to contract with the lower recruitment-per-spawner in dry years. There is also a strong pattern of reduced abundance in the past three decades, starting with a sharp decline in recruits per spawner in the 80’s and 90’s often attributed to the proliferation of exotic clams, the 2001-05 period often referred to as the Pelagic Organism Decline (POD), and the drought periods of 2007-09 and 2012-15.

A closer look at these patterns in Figure 3 indicates possible explanations for the overall 50-year pattern of trending lower numbers of spawners and recruits, and recruits per spawner, over time. In the 70’s, the population expanded initially with the abundant 1970 year-class that featured a high number of recruits-per-spawner, followed by another increase with the strong 1978 year-class. The population was sustained by high recruits per spawner through the wet and dry years of the 70’s. In the 80’s and 90’s, recruits per spawner dropped sharply in drier years, while remaining relatively high in wetter years. A sharp drop in the spawning population occurred after the 1980 fall peak (red 81). In the 80’s and 90’s, the population had matching upward (Group B) and downward (Group A) movements that maintained the population into the early 2000’s (00, 01, and 02). Despite low recruits per spawner in the 87-92 drought, the population rebounded in the wet years from 93 to 99. The population then took a sharp drop from the high fall level in 99 to the much lower level in 04 and the very low recruit-per-spawner year 05. Again, that latter period corresponds to the POD and a drier 00-05 period with four normal and two dry years. There was a sharp uptick in recruitment per spawner in wetter 10-11 (Group C) following the dry years of 07-09, but the population collapsed again with very poor recruitment per spawner in 2012.

The lower recruits-per spawner in drier years can be explained by low Delta outflows and high exports in winter and spring of drier years. This is best exemplified by comparing Groups A and B in Figure 3. The low recruits per spawner in 05, followed by the drought of 07-09, defined the late 2000’s (Group D). A short recovery period in 10-11 (Group C) was crushed by the poor recruits per spawner in the drought period of 12-16. The poor number of recruits in 15-16 (Group E) is simply a lack of spawners (low eggs) and continuing drought conditions.

Figure 3. Groupings A to E in Log vs Log plot (Figure 3) of Summer Index of Delta smelt as related to the previous Fall Index of abundance, by year of summer index. Blue years are wet water years (Oct-Sept). Green years are normal water years. Red years are dry and critical water years. Year types are as determined by the California Department of Water Resources for the Sacramento Eight-River Index.

The relationship between summer juvenile production as reflected in the STN index for the year and survival as reflected in the following fall adult FMWT index is shown in Figure 4. The comparison represents the relative survival between summer and fall, most likely reflecting July-September conditions in the Bay-Delta. The strong positive relationship indicates that the number of juvenile smelt in summer determines in large part the population in the fall, adjusted by summer-fall environmental conditions that can significantly affect survival to the fall. Again, Delta inflow/outflow and exports are likely factors in defining the survival relationship, over and beyond the beginning summer numbers of smelt. As in the previous fall to summer relationship described earlier, summer to fall survival is generally higher in wetter years, with notable exceptions. These exceptions are due mainly to the fact that conditions in the Bay-Delta in many summers, regardless of water-year type, are drought-like: there is often little difference between wet and dry year summer-fall conditions. Note the pattern of falling indices over the five decades of the surveys.

A closer look at the pattern in Figure 5 indicates possible explanations for the overall 50 year pattern of trending lower numbers of fall survivors from summer juveniles, and fall production per summer juvenile production level index over time. In the 70’s, the population was high and remained so through 1982. Reduced summer to fall production from 1976-81 led to a lower 1982 population. The subsequent declines from 1982 to 1985 have been attributed to the 80s clam invasion, although there was no apparent decline in summer to fall survival. Poor summer to fall survival in 2004 led to a sharp downward population shift. Group A is indicative of poor over-summer survival in high-export dry years. Group B represents very wet years when part of the population is distributed below the survey area. Group C represents moderately wet years under low to moderate Delta exports. Group D includes wet years and three dry years with low summer exports. Near zero 2015-16 summer indices led to near zero fall indices, a pattern indicative of recruitment failure, where summer production is so low that only low numbers remain in the fall.

Figure 4. Log vs Log plot of fall FMWT Index of Delta smelt as related to the prior summer STN Index of abundance for that year. Blue years are wet water years (Oct-Sept). Green years are normal water years. Red years are dry and critical water years. Year types are as determined by the California Department of Water Resources for the Sacramento River runoff to the Bay-Delta Estuary ( ).

The plot of LogFall to following LogFall indices (Figure 5) indicates strong recruitment in wet years and poor recruitment in dry years. While the prior year or starting abundance remains the dominant factor as in the above relationships, generally higher recruits-per-spawner occur in wet years and lower recruits-per-spawner occur in drier years. The poor recruitment years (81, 05, and 12) led to sharply negative population shifts. Multi-year droughts 07-09 and 12-15 also led to declining year-to-year population levels. Good recruitment years (e.g., 70, 93, 95, and 11) led to strong positive population recruitment.

Figure 5. Log vs Log plot of fall FMWT Index of Delta smelt (recruits) vs previous fall index (spawners). Blue years are wet water years. Green years are normal water years. Red years are dry and critical water years. Year types are as determined by the California Department of Water Resources for the Sacramento River runoff to the Bay-Delta Estuary ( ).


The population dynamics of Delta smelt are characterized by a strong positive spawner-recruit relationship, modified by wet-dry year conditions. Dry year sequences drive population abundance down, hindering future abundance levels. Wet years generally lead to higher recruitment per spawner. The number of spawners remaining in 2017 may be too low to sustain the population and bring about recovery without extraordinary positive measures such as improved flow conditions, reduced exports, and/or stocking of hatchery-reared Delta smelt.

State Puts Fall X2 Back Where It Belongs

The State of California, after initially complying with the Bureau of Reclamation’s request to remove the Fall X2 protections for Delta smelt,1 has had second thoughts. Instead, the Department of Water Resources has cut exports at Clifton Court to keep X2 (roughly 3800 EC) at km74 (near Mallard Island).

  1. “Fall Smelt Protections Removed,” October 1, 2017,

Fall Smelt Protections Removed

On September 28, the US Fish and Wildlife Service (Service) approved removal of fall protections for Delta smelt that have been in place since 2008. The action allows south Delta pumping plants to export an additional 400,000 acre-feet of water on top of the 6.2 million acre-feet already exported through September in Water Year 2017. The water, earmarked for the Bay and Delta smelt, instead will go to southern California to fill reservoirs.

The action allows X2, the 2 parts per thousand salinity prescription, to be moved from Chipps Island (river kilometer 74) upstream to Collinsville (river kilometer 81). The action occurs simply by increasing south Delta exports, keeping all other factors constant (Figures 1 and 2). Exports have risen from 8,000 cfs to the maximum of 11,700 cfs. Delta net freshwater outflow to the Bay has fallen from 15,000 cfs to 10,000 with the higher exports and slowly falling Delta inflow (Figure 3). Salinity at Collinsville has nearly reached its new allowed level (Figure 4).

The effects of the higher exports can be seen in flows measured in Old River in the central Delta near Highway 4 (Figure 5). Flows through nearly the entire tidal cycle are negative as water rushes to meet the maxed-out exports in the south Delta. The daily average, also called OMR, is -5,000 cfs. Other channels, including the lower San Joaquin River, make up the remainder of the 11,700 cfs level of export.

The Service concludes that “the proposed Fall X2 action for 2017 would not adversely affect Delta Smelt” P5. They state that they see no evidence that the change will affect the smelt population. This is an incredible conclusion given the present state of the population (Figure 6). There is simply no basis for the conclusion other than saying the smelt are all gone anyway.

Reductions in Delta outflow, upstream movement of X2 into the western Delta, and negative net flows in any Delta channel are a direct and real threat to Delta smelt and their habitat (as the Service points out in its approval letter on page 8). In Reclamation’s request for the action, Reclamation frames the issue an adaptive management action within the context of the original 2008 biological opinion prescription. With the species on the brink of extinction, such negative “adaptive management” actions are not the logical approach to be taken toward recovery of the species. The prescription allowed adaptive management actions to help toward recovery, not to top off southern California reservoirs.

Sad thing is, 2017 is only the second year with hydrological conditions applicable to the 2008 fall X2 prescription. In 2011, the first and now only application of the prescription, the fall X2 requirement proved to contribute significantly toward recovery, as shown in the Fall Midwater Trawl Survey. I suspect there will be no similar “bounce” in the October-through-December survey index in 2017.

Figure 1. Tracy (federal) exports in September 2017.

Figure 2. Clifton Court (state) exports in September 2017.

Figure 3. Delta outflow to Bay in summer 2017.

Figure 4. Salinity (EC) at Collinsville (river kilometer 81) in September 2017.

Figure 5. Hourly flow in cfs in Old River in central Delta near Highway 4 crossing.

Figure 6. Delta smelt summer townet index 1969-2017. (CDFW data).

Figure 7. Fall midwater trawl index for Delta smelt