Striped Bass Status – Summer 2019

Posted on August 21, 2019 by Tom Cannon

I last reported the status of striped bass in 2016. The prognosis was not good after four years of drought (2012-2015). Today, after a sequence of water years (2016-2019) that were below normal, wet, below normal and wet, the prognosis has not improved, notwithstanding the remarkable resilience of striped bass.

After improving in below-normal 2016 and wet year 2017, the below-normal 2018 fall index equaled that of below-normal 2010, the lowest since 2000 (Figure 1). A similar pattern occurred in the 2018 summer index (Figure 2).

The summer-to-fall recruitment relationship (Figure 3) shows a continuing strong relationship between the summer index and fall recruitment. Furthermore, the relationship continues to show a positive response in wet years (2011 and 2017), but a poor response in the below normal years (2010, 2016, and 2018). This indicates that summer conditions in these below-normal water years is depressing the fall recruitment of striped bass.

Early indicators for wet year 2019 give me pause and further concern for striped bass recruitment this fall. First, numbers and densities in the 2019 late spring 20-mm survey were way down as compared to 2017. Second, despite high south Delta exports in July 2019, juvenile striped bass salvage is also lower compared to July 2017 (Figure 4), consistent with the lower 20-mm survey results. The summer and fall indices for 2019 will help complete the story.

Figure 1. Striped bass fall index 2000-2018.

Figure 2. Striped bass summer index 1959-2018.

Figure 3. Striped bass Fall Midwater Trawl Survey Index (log10[index+1]) versus prior Summer Townet Index (log10). Select years labeled, with color of number showing year type: blue=wet, green=normal, and red=critically dry.

Figure 4. Striped bass salvage at south Delta export facilities with export levels (acre-feet) summer 2017-summer 2019. Note near maximum export levels in July 2017 and 2019.

Delta August Adjustment

Posted on August 12, 2019 by Tom Cannon

The State of California has markedly increased inflows to the Delta and reduced exports in early August 2019 (Figure 1). There is no announced reason for this major hydrologic adjustment that has had a major effect on Bay-Delta habitat. The likely reason was to maintain the 14-day average salinity standard of 450 EC at Jersey Point,¹ which was exceeded on a daily basis beginning on August 10 (Figure 2).

“Adjustments” to Delta inflow and exports began at the end of July as daily Jersey Point salinity began to exceed the 450 EC standard. The federal Central Valley Project made little or no contribution to this correction.

These recent changes are a textbook example of why the 14-day salinity standard needs to change to a daily standard. State water managers gamed easily controlled parameters, using the 14-day average to squeeze out more exports through July. This operation caused a major system reaction with far-reaching consequences to the State Water Project system and to the Bay and Delta.

The state could have maintained a daily 450 EC limit with gradual small system adjustments and support from the CVP.

Further discussion of the effects follows below.

Figure 1. Sacramento River Delta inflow at Freeport (FPT flow), Delta outflow (DTO resflow), state exports (HRO pumping), and federal exports (TRP pumping), 7/1-8/9, 2019. Note only state exports were affected.

Figure 2. Salinity (EC) at Jersey Point near mouth of San Joaquin River in the Delta 7/14-8/10, 2019.

Delta Inflow
Sacramento River inflow to the Delta at Freeport increased about 3000 cfs to just over 20,000 cfs (Figure 3). The extra flow came from the Feather River (Oroville Reservoir of the SWP). The higher inflow coincided with a drop in water temperature at Freeport from 23^oC to 21^oC.

Delta Outflow
Delta outflow rose about 9000 cfs from near 7000 cfs to 16,000 cfs (3000 from inflow and 6000 from reduced exports, Figure 1). Outflows rose in the Sacramento channel at Rio Vista (Figure 4) and San Joaquin channel (Figure 5). Water temperatures also fell about 1^oC.

Interior Delta
Flow also increased and water temperature fell in Georgianna Slough (Figure 6).

Suisun Bay
Salinity and water temperature fell in Suisun Bay west of the Delta (Figure 7).

Figure 3. Flow and water temperature in Sacramento River at Freeport 7/1-8/10, 2019.

Figure 4. Flow and water temperature in Sacramento River at Rio Vista, 7/1-8/10, 2019.

Figure 5. Flow and water temperature in San Joaquin River at Jersey Pt, 7/1-8/10, 2019.

Figure 6. Flow and water temperature in Georgianna Slough in the central Delta, 7/1-8/10, 2019.

Figure 7. Salinity and water temperature in Suisun Bay near Pittsburg, 7/1-8/10, 2019.

The standard applies for wet years through August 15. ↩

Delta Science Plan – It’s not that complicated

Posted on July 26, 2019 by Tom Cannon

From Delta Science Plan Figure 1-1 | Network map of collaborative groups in the Delta

The new Delta Science Plan (Plan) is a “call” for more collaborative science to improve government decision making affecting the Delta ecosystem. The first page announces the vision for the plan as being “One Delta, One Science.” Really?

Science is not just one thing; it is many things. Science is knowledge. Delta science is knowledge on what makes up the Delta and how it all works together. There is science for all Delta social, economic, and ecosystem components. There is Delta smelt science. There is Sandhill Crane science. There is science on water quality, water supply. There is science on roads, farming, and flood control. There is science on large ship movement through the Delta. The Science can be good, bad, or simply inadequate; it is only as good as the predictions and decisions that one can make from it.

What is missing from the current Plan is a presentation of the major actions that will affect the Delta ecosystem and the ramifications these actions would have on the ecosystem. Also missing is a description of key decisions to be made relating to these actions and the associated science needed to make the decision.

Each ecosystem component should have science and advocates that can assess how specific actions can affect the resources related to that component. Delta smelt should have its science and advocates. These folks need not communicate with the crane folks. On the other hand, the smelt folks may need information from the water folks. Each action should have its own science and science group to understand what the action entails and how it might affect other ecosystem components. Each decision process and decision group should have its science. Each group may need information from other science groups.

The Plan should include a compilation of each ecosystem component’s science and needs, and a clear depiction of the important actions and decisions under consideration for that component. A good plan would summarize the science of each ecosystem component, each major action being considered, and each major decision being contemplated.

The overall success of the Plan will depend on how good the science is in predicting outcomes. Each science group is responsible for its own science, as well as how other groups use it.

Stakeholders need a Plan that instills confidence that each ecosystem group knows its science. Stakeholders also need to know what actions are being planned and how decisions will be made.

Personally, I want to see what the smelt science indicates that smelt are lacking in the Delta ecosystem. I want to see a description of how the USFWS/CDFW plan to restore Delta smelt. I want to see how the State Board plans to set new Delta water quality standards. I hope to see how Delta levees will be addressed. I want to know whether Delta flow barriers are being considered and what factors may affect that decision. I am interested in the future for Sandhill Cranes and the factors that may affect that future. And I want to know how each ecosystem component will address climate change.

In summary, I want to see a plan that includes a description of our understanding of each key Delta ecosystem component, what actions involving the Delta are being considered, and what decisions that might affect the Delta are being contemplated.

Delta June 2019

Posted on July 19, 2019 by Tom Cannon

Water year 2019 has been a very wet year. Yet salmon and sturgeon survival was compromised by low flows and high water temperatures in the Sacramento River this spring.¹ Young salmon survival has been further compromised by low flows, high exports, and high water temperatures in the Delta this past June.

Many of the wild smolts produced in Central Valley rivers this year entered the Delta in May and left (or died) by the end of June, as observed in Delta export salvage collections (Figure 1). Many of the wild smolts captured in the south Delta likely originated from San Joaquin tributaries. South Delta exports were near maximum at 10,000 cfs, about 70-80% of San Joaquin inflow to the Delta and 20% of total Delta inflow. The high exports caused lower flows and associated high water temperatures (>20^oC) in the Delta channel of the lower San Joaquin River (Figure 2), and contributed to similarly high temperatures in the lower Sacramento River channel (Figure 3).

The high Delta water temperatures (>20^oC) compromised the survival of the salmon smolts in June. Reducing the export limit to 5000-6000 cfs in June of this wet year would have kept the water temperature near a 20^oC limit. The water quality standards in the 1980’s and 1990’s under D-1485 had a 6,000 cfs June export limit. In the past two decades under D-1641, the June export limit changed to 65% of total inflow.

New Delta water quality standards should provide export limits and inflow/outflow minimums that protect salmon through the spring months.

Figure 1. Chinook salmon salvage at south Delta export facilities in 2019. Note the prevalence of wild (non-hatchery) smolts in May-June.

Figure 2. Water temperature and tidally-filtered flow at Jersey Point in the lower San Joaquin River channel of the Delta in June 2019.

Figure 3. Water temperature and tidally-filtered flow at Rio Vista in the lower Sacramento River channel of the Delta in June 2019.

http://calsport.org/fisheriesblog/?p=2673 ↩

Delta Smelt – Spring 2019 Status

Posted on July 5, 2019 by Tom Cannon

Late April and early May 20-mm Surveys provide an excellent picture of the status of Delta smelt population in the estuary. Since 2017, some surveys collected no Delta smelt (Figures 1-3) in the San Francisco Bay-Delta estuary. The 2018 and 2019 survey catches (Figures 1 and 2) are a new low for Delta smelt, lower even than the 2017 survey catch (Figure 3), and the lowest in the 1995-2019 survey period.

The outlook for the Delta smelt population remains grim after these lows. Despite good conditions in spring 2018 and 2019, the severely depressed number of adult spawners indicates a continuing weak potential for recovery.