This post addresses more from the November 2016 Bay-Delta Science Conference. In this latest review I focus on:

“Part 2: Collaborative Adaptive Management Team (CAMT) Investigations: Using New Modeling Approaches to Understand Delta Smelt State Salvage Patterns at the State Water Project and Central Valley Project”.¹

First, some context:

“The Collaborative Adaptive Management Team, comprised of high level managers and senior scientists, is the group that works underneath the CSAMP² policy group. The CAMT was established [in 2013] to work with a sense of urgency to develop a robust science and adaptive management program to inform both the implementation of the current BiOps and the development of revised BiOps.”

Delta Smelt Salvage

“CAMT examined historical (1993-2015) salvage data to determine what factors affected Delta Smelt salvage at the State Water Project (SWP) and Central Valley Project (CVP) fish facilities. The objective was to determine if new approaches could be applied to the data to yield new insights about the factors that explain Delta Smelt salvage patterns within and across years.”

Comment: First, it is surprising that CAMT would apply “new” approaches and “insights” given that so much has been studied and learned about Delta smelt salvage at the south Delta pumping plants. The salvage problem had been addressed by limiting exports in winter and spring with OMR limits³ and active management by the Smelt Working Group (SWG), an effort that is both highly sophisticated and effective. The working group’s measures have markedly reduced salvage losses but have failed to curb the population decline. The measures came far too late, and managers often did not take the SWG’s advice.

More study of salvage is not going to help in learning more about the population decline. Less than ten Delta smelt were salvaged so far this winter (compared to thousands per day historically). The study of the population decline should be focusing now on freshwater inflow, Delta outflow, and spring-to-fall habitat conditions (i.e., Low Salinity Zone and water temperatures), and on the indirect effects of Delta exports. It would be far more effective to showcase the SWG’s actions and other actions required by the biological opinion and by water quality standards, It would also be more consequential for the CAMT to evaluate the consequences of weakening these standards in drought years.

“Mr. Grimaldo said that one of the initial sparring matches within the CAMT team was over conceptual models.”

Comment: The CAMT analysis and conference focused on adult Delta smelt winter salvage and the modeling effort employed to understand it. Why? Because the CAMT water contractor members do not like cutting back on exports during the infrequent winter storms in dry years, when the smelt make their spawning runs. Much of a dry year’s water supply comes in infrequent winter storms. Under the conceptual model, higher exports at such times simply draw the smelt spawners into the south Delta⁴ to be salvaged (killed at fish screens or lost in forebay). When the spawn is in the south Delta, it also makes the annual production of larvae more vulnerable to unmonitored/unmeasured entrainment into the export pumps later in spring. The US Fish and Wildlife’s Delta Smelt Biological Opinion addresses these risks by limiting winter-spring exports. There is no doubt that until these risks are further reduced, there will be no recovery of the Delta smelt population (or other listed Delta fish). Furthermore, until protective actions are extended to Delta outflow, salinity, and water temperatures, there will be no recovery, and the conflict with water supply will remain unresolved and a perpetual problem.

“Grimaldo acknowledged that the Fall Midwater Trawl nowadays is pretty lousy for sampling Delta smelt. “We get very few,” he said. “So this problem is even worse as now we don’t even have a gear, so we don’t even have an idea what the size is coming into December.”

Comment: There is nothing wrong with the Fall Midwater Trawl Survey. It captures few smelt because there are few left. All the surveys support this conclusion (see chart below). We are doing just fine in data gathering with the Smelt Larval Survey, the 20-mm Survey, the Summer Townet Survey, the Fall Midwater Survey, and the Fish Salvage Survey.

The relationship (log-log) between the fall midwater trawl index and the subsequent summer townet survey index (year noted) is remarkably significant, especially when water-year type is taken into account. Red years are dry/critical. Green years are below/above normal. Blue years are wet.

“Grimaldo suggested that a Kodiak trawl should start in September. “We know that it catches fish better than the fall midwater trawl. I think folks just have to make the leap. I think folks are used to the Fall Midwater Trawl being this 40 year plus monitoring device, but maybe we need to switch things up, because we know from other work that Ken Newman and Randy Baxter are doing that this Kodiak is a better gear for sampling Delta smelt, so why not go for it. This could potentially allow for salvage losses to be evaluated in the context of a recruit responder model,” he said. “At least you could have an idea going into the salvage season what your salvage actually means.”

Comment: The context that matters is that the indices and salvage are near zero and have been for several years. Yes, the highly effective Kodiak trawl would be more effective at near zero population. Do we really want to manage the population down at zero, or do we want to smelt to recover?

Final point: It is sad that we have to resort to court-directed science in the form of CSAMP/CAMT to resolve the perpetual conflict between water management and the Delta ecosystem. All the effort will be focused on how the ten smelt salvaged this year could have been reduced to five.

The last post about risk to Delta smelt was on January 9. Adult smelt migrate into the Delta from the Bay in winter to spawn. They take advantage of the flood tide to move upstream. However, with flood flows as high as 100,000 cfs entering the north Delta from the Sacramento River, the Yolo Bypass, and Georgiana Slough in mid- to late January 2017, there are no flood tides to ride into the north Delta spawning areas.

The only option for the adult smelt is thus to ride the incoming tide up the San Joaquin River into the central and south Delta (Figure 1). South Delta export pumping is currently at 14,000 cfs, near maximum capacity, using four rarely used auxiliary pumps. This pumping increases the pull of the incoming tide, reducing the effect of the inflow from the San Joaquin, Calaveras, Mokelumne, and Cosumnes rivers. While Delta inflow from these rivers is relatively high (Figures 2-5), it does not offset the influence of the incoming tide as does the inflow from the Sacramento.

Net tidal flows in lower Old and Middle Rivers (OMR flows) remain at the allowed limit of -5000 cfs, consistent with the smelt Biological Opinion. Several adult Delta smelt were salvaged at the export facilities in mid-January. ¹ This scenario is considered a “high risk” to Delta smelt by the Smelt Working Group, because of the continuing risk that the pumps will draw or attract adult smelt into the central Delta and subsequently into the south Delta.

Under lower San Joaquin River flows, the maximum allowed export pumping is 11,400 cfs. High San Joaquin River inflow allows exports of 14,000 cfs that do not generate OMR flows more negative than -5000 cfs. The theoretical benefit of high San Joaquin River flows is that it should keep flow into the central and south Delta moving westward. But a large portion of that inflow is diverted south into the Head of Old River toward the pumping plants (Figure 6).

Figure 1. Approximate flood tide flow in cubic feet per second in mid to late January 2017. Blue arrows represent high Sacramento River, San Joaquin River and Mokelumne River flows (during flood tides). Red arrows depict negative flows of incoming tides. Note the south Delta incoming tide of -20,000 cfs would be less if not for the 14,000 cfs export rate at the south Delta pumping plants.

Figure 2. San Joaquin River flow at Mossdale at the head of the Delta upstream of Stockton and the Head of Old River. Note that on Jan 6 when flow reached about 6,000 cfs, the tidal signal dissipated when flow overcame the tidal forces.

Figure 3: Flow from the Calaveras River, upstream of the Delta. The Calaveras enters the Delta at Stockton.

Figure 4. Release from Camanche Dam to the Mokelumne River. CDEC does not show flow values for the Mokelumne at gages further downstream. The Mokelumne enters the Delta near Jersey Point.

Figure 5. Cosumnes River flow well upstream of the Delta. Much of the high flow peaks enters the river’s connected floodplain, roughly between Lodi and Elk Grove, and does not flow immediately to the Delta. Flows in the Cosumnes enter the Mokelumne before passing into the Delta

Figure 6. Flow entering the entrance to Old River from the San Joaquin River near Stockton.