In my March 12 post, I related that Senator Feinstein’s request for higher Delta exports would put the Delta Smelt population in the Delta at further risk of extinction. Well, she received her wish, and exports increased from 6000 cfs to 8000 cfs (11,400 cfs is maximum pumping capacity) in the week after her request when storms brought more inflow to Delta from the San Joaquin River.

However, the higher exports were short–lived, because the 3/14-3/17 Smelt Larvae Survey picked up larval smelt for the first time this year (Figure 1 – green dots). Exports dropped below 5000 cfs again. Though only two newly hatched larvae were collected in the central Delta, their presence is a concern. The presence of larval smelt shows that smelt are spawning in the lower San Joaquin River in the central Delta. According to the Smelt Working Group the net negative flows shown in red in Figure 1 for late March indicate a “medium” risk to smelt and a likelihood that larval smelt will be drawn toward the south Delta export pumps.¹ The -5000 cfs Old and Middle River (OMR) reverse flows are the maximum allowed under the Smelt Biological Opinion.

In its review of the results of particle tracking model runs, the Smelt Working Group concluded: “Members stressed the importance of weighing more heavily the results from inserting (particles) at Prisoner’s Point, given the consistent catch of adults there this year and the hydrologic proximity of that location to the south Delta (as compared to Jersey Point). For OMR flow of -5000 cfs, approximately 20% of the particles inserted at Prisoners Point were entrained into the South Delta. For an OMR flow of -2500 cfs, approximately 10% of particles inserted at Prisoners Point were entrained into the South Delta. For an OMR flow of – 1250 cfs, less than 10% of particles inserted at Prisoners Point were entrained into the South Delta.” Prisoners Point is the green dot from the right on the Figure 1 map. In all likelihood, larval smelt are now being drawn or will soon be drawn into the south Delta. It is too early to determine what portion of the population is subject to this risk. But given the unprecedented depressed condition of the smelt population after four years of drought, the risk is significant.

On March 24, after review of “Smelt Working Group’s March 21 recommendations,² the U.S. Fish and Wildlife Service “determined”³ that the OMR should be no more negative than -2500 cfs on a 14-day average, and no more negative than -3150 cfs on a five-day average. Reclamation took a slightly more liberal interpretation in the subsequent week’s operations (Figure 2), staying nearer -3500 cfs most of the week with no apparent interest in reaching a -2500 cfs 14-day average. It could be that the Service meant to recommend a -3500 cfs OMR limit. Or maybe the Service got a call from Senator Feinstein’s office. We shall see what this week’s meetings and determinations offer.

In any event, the risk to Delta Smelt remains “medium” at combined exports of about 3500-4000 cfs. With an export capacity of 11,400 cfs, Delta outflow still exceeding 50,000 cfs, reservoirs continuing to release snowmelt, and San Luis Reservoir in the San Joaquin Valley only half full, there will be continued cry for more exports and for approval of the Tunnels. In the meantime, it appears from Figure 1 that some smelt larvae and a good amount of snowmelt are escaping west to Suisun Bay, while some larval smelt remain at risk in the central Delta.

Figure 1. Net daily flow in Delta in late-March 2016. (Gage data source: USGS). Green dots are location of seven Delta Smelt larvae collected in Survey 6 of Smelt Larvae Survey (http://www.dfg.ca.gov/delta/data/sls/CPUE_Map.asp ).

Figure 2. OMR March 23 to March 28. (Source: CDEC)

The February trawl survey indices are in – there are a few Delta Smelt left (Figure 1).

The Smelt Working Group, created as prescribed in the Smelt Biological Opinion issued by the US Fish and Wildlife Service (in the Department of Interior), has stated following its meetings on February 15 and 22: “The fact that sporadic Delta Smelt catches have continued to occur at Prisoners Point under the lowest February SKT survey on record indicates that the risk of entrainment remains high and is incompatible with current pumping levels.” ¹

After its February 22 meeting, the Working Group added: “Salvage: Four delta smelt on February18, geographic influence of the pumps extends to the lower San Joaquin River at the more negative end of this flow range, especially affecting the southern bank near Jersey Point. Recent salvage of adult Delta Smelt confirms that entrainment into the export facilities has occurred and likely is continuing…. The Working Group concluded that any salvage observed at either facility will be of high concern because Delta Smelt abundance is at a historic low, contributing to low detection probability of Delta Smelt in salvage under RPA compliant operations (BiOp page 338). One fish was detected in salvage sampling on January 21 and February 18, counting as eight salvaged Delta Smelt due to an expansion factor of four.”

Following these meetings, the US Bureau of Reclamation (also in the Department of Interior), which operates the federal export pumps in the South Delta, exported more than double the recommendation of the Smelt Working Group. Together the state and federal exports were nearly triple the recommended amount (<2000 cfs). This situation, where the state and federal experts in the Smelt Working Group were ignored by their managers, who instead maximized Delta exports in February, is a gross violation of the intent of the state and federal endangered species acts and species protections in the biological opinion. Figure 1. Record low indices for Jan-Feb 2016 in Kodiak Trawl Survey²

This third week of February 2016 the Smelt Working Group concluded “the risk of entrainment remains high and it is incompatible with current pumping levels”¹. Basically as Delta inflows decline after the early winter stormwater recedes in early February and South Delta exports increase, the risk to Delta Smelt is high with the onset of spawning imminent. Despite the high risk assessment, state and federal managers have decided to raise exports to the maximum allowed under the Delta Smelt Biological Opinion, to 6,000 cfs, which is triple the 2000 limit suggested by the working group, and about a third of Delta inflow. The working group warns the managers that just because there are few smelt being seen in Delta surveys does not mean that the remnants of the populations are not at risk.

The working group is also concerned with what may soon occur once smelt do start spawning. As Longfin Smelt have begun spawning, I have summarized recent data to specifically look at that risk. Figure 1 shows the recent early February Smelt Larval Survey results along with annotations of net flows. Under 6000 cfs exports negative upstream net flows occurs throughout the central Delta (red arrows). The larval smelt in this area will transport to the south Delta over time. With spawning smelt in this area, their offspring will also likely move south to the pumping plants.

With most of the larval Longfin in Suisun Bay because of the earlier storm flows, the risk to the population is low. Yet, these are a state endangered species with these export operations causing a measurable take. With Delta Smelt yet to spawn, they are more likely to be found further upstream because of lower Delta inflows, thus putting their larvae at greater risk than Longfin, especially given ripe adults are present in the central Delta.

One final note, with these operations and declining Delta inflow, the low salinity zone where smelt larvae concentrate will be drawn ever eastward from eastern Suisun Bay into the central Delta. This pattern will increase the risks to smelt. The upstream edge of the low salinity zone is moving upstream in the lower San Joaquin channel with the higher exports as seen at Antioch (Figure 2) and False River (Figure 3).

Figure 1. Early February Longfin Smelt densities from Larval Smelt Survey² with added annotations of net flow in the Central Delta zone of influence (red circle) of the South Delta exports. Blue circle shows catch at Jersey Pt station (809). Red arrows depict net negative flows on the order of 400-5000 cfs³. (Note these early February Longfin larvae densities are by far the lowest observed in the eight years of surveys.)

Figure 2. Salinity (EC) at Antioch in the San Joaquin channel of the west Delta during February 2016. (Source: CDEC)

Figure 3. Salinity (EC) in False River in the central Delta during February 2016. (Source: CDEC)