Largemouth Bass Production in the Delta

I had the unique opportunity to study fish use of shallow inshore waters of the western Delta in 1978-79 and again in 2004-05. One of the biggest differences I noticed after 25 years was the increase in Largemouth Bass production. Mitigation areas where levees were breached allowing tides to enter-and-leave tidal ponds without flow-through were virtual Largemouth breeding factories. Areas where channel entrances had filled in and circulation reduced also were prone to aquatic plant proliferation and an abundance of non-native lake/pond fish including Largemouth, sunfish, and shiner minnows. Flow-through areas and tidal channels with two ends had lower Largemouth production (and more native fishes). Limited tidal circulation also caused prolific amounts of aquatic vegetation including water hyacinth, Egeria, milfoil, Parrots Feather, and Potamogeton. Dense beds of aquatic vegetation also occurred in bays, dead-end sloughs, breached islands, and protected shorelines.

A recent study1 relates higher Largemouth production to increases in aquatic plants, specifically relating the abundance of young Largemouth to Egeria. They also found young Largemouth more abundant in warmer waters, another feature of backwater areas. Aquatic plants slow currents, capture sediment, and absorb sunlight, which all contribute to warming of shallow waters.

One of the paper’s conclusions related to future habitat restoration:

“While these efforts will expand the largely missing shallow-water habitat in the Delta, a major concern is that increased shallow water area will expand the habitat for Brazilian waterweed and consequently increase the abundance of Largemouth Bass, creating a predation sink for target native fishes (Brown 2003).”

I have some points of disagreement with these conclusions. First, I do not believe the Delta lacks shallow water habitat. The problem, rather, is that too much of existing shallow water habitat is bad habitat more conducive to non-native warm water fish. Second, good shallow habitat along the edges of the bays and rivers has been and continues being lost to riprapping, ship-channel dredging, remnant soft-levee erosion, and filling with sediment.

I concur with the paper that much planned restoration will create more bad habitat. Instead we should be protecting good habitat and converting more of the bad habitat to good habitat.

For more on the subject of Delta habitat restoration see: http://calsport.org/news/cspas-assessment-of-historical-habitat-restoration-in-the-delta/ .

Cease and Desist DWR! – January 7, 2016

DWR – It just started raining and you already ramped up Delta exports again despite all the salt water and the risks to endangered Winter Run salmon and Delta Smelt. I recently suggested “Whoa,”1 as did Smelt Working Group. At least wait until the runoff from the storm hits the Delta.

The Smelt Working Group concluded on December 30: “The Working Group reviewed Delta Smelt distribution conditions. The working group concluded that entrainment risk has increased. This is based on fish distribution combined with increased water exports, but the group provided no recommendation for a change in water export reduction for either Delta Smelt or Longfin Smelt. This decision was based on the projected decrease in OMR flows from -5600cfs today to -2100cfs on Monday, 1/4. The group will be monitoring conditions closely over the next several days.” But no sooner had January 4 arrived than exports jumped sharply to even higher than the late December level (Figure 1), despite all the early warning signals brought up by the Working Group2.

Graph of Clifron Court Exports

Figure 1. State Water Project Delta exports at Clifton Court Forebay in past month.

The higher exports, in combination with spring tides, have pushed the Low Salinity Zone further east and south into the Delta (Figure 2). (Note: the ten-day charts readily depict recent increased salinity.)

Aerial map of salinity in Delta

Figure 2. Aerial photo with salinity levels (charts of EC), freshwater inflow (blue arrow), negative net inflows of brackish water (red arrows), and route taken by juvenile Winter Run salmon (yellow arrows). Clifton Court at bottom center.

Perhaps more ominous is the increase in salvage of Winter Run salmon (Figures 3 and 4). Twenty-seven were salvaged on 1/6. Given poor salvage efficiency (near 10 % in forebay alone) and the likely presence of many Winter Run trapped in the central and south Delta, as well as the desperate state of the Winter Run population, this is no time to be increasing exports. Where is the Salmon Working Group? This is serious “take”; authorized or not, NMFS should be doing something.

Graph of Salvage of Winter Run

Figure 3. Salvage of Winter Run at south Delta fish facilities. (Missing from this graph is 1/6 salvage that is depicted in Figure 4.) Source: http://www.dfg.ca.gov/delta/apps/salvage/SalvageExportChart.aspx?Species=1&SampleDate=1%2f2%2f2016&Facility=1

Table showing the Salvage of Winter Run

Figure 4. Salvage of Winter Run salmon at south Delta fish facilities 1/1-1/6 2016. Source: http://www.usbr.gov/mp/cvo/vungvari/salmondly.pdf

Whoa on the Delta Exports DWR

The California Department of Water Resources (DWR) and the US Bureau of Reclamation (USBR) recently raised south Delta exports from 800 cfs (12/15) to 6,700 cfs (12/29). Delta outflow of freshwater has declined from 27,000 cfs (12/25) to 5,300 cfs (12/29) in just four days. Though these conditions are allowed in Delta standards, the standards must be changed.

Under these conditions, with the Delta Cross Channel gates closed (per standards), water is pulled from the central and west Delta toward the south Delta export pumps (Figure 1). The problem is that remnants of the Delta smelt population have moved into the west and central Delta on their annual winter spawning migration, as shown in early warning surveys at Jersey Point (Figure 2). Negative net flows (Figures 3-6) draw fish to the pumps and disrupt the salinity field and Low Salinity Zone. Exports also continue to take brackish water (Figure 7) – not good for fish, crops, or humans. They also take juvenile salmon emigrating through the Delta (Figure 8).

Map of Delta Flows Dec 2015

Figure 1. Delta net flow patterns in late December 2015 – positive (blue arrow) and negative (red arrows).

Graph of False River Flows

Figure 3. False River (middle left red arrow in Figure 1) net flows have turned negative with lower Delta outflow and higher exports.

Graph of Three Mile Slough flows

Figure 4. Three Mile Slough (top left red arrow in Figure 1) net flows have turned sharply negative with higher exports.

Graph of Jersey Point flows

Figure 5. Jersey Point (left end of middle left arrow in Figure 1) net flows have turned negative with higher exports.

Graph of Old and Middle River Flows


Figure 6. Net flow in Old and Middle Rivers in south Delta (large lower right arrow in Figure 1) has turned sharply negative with higher exports.

Graph of EC at Clifton Court

Figure 7. Salinity levels (EC) in Clifton Court Forebay in December 2015.

Graph of Chinook and Exports

Figure 8. Salvage of Chinook salmon and export rate at Clifton Court Forebay in December 2015. Many of these salmon are likely endangered Winter Run and Spring Run.

It is Too Early to Turn On the Delta Pumps

Delta export pumping has increased, jeopardizing endangered Winter Run salmon and Delta smelt. Yes, there is a lot of fresh water (and young salmon) pouring into and through the Delta from the recent storms. Delta outflow has risen from 5000 cfs to 22,700 cfs this month (Figure 1). So the state has started pumping more from the south Delta. State exports have risen from 500 cfs on 12/21 to 4000 on 12/23.

The problem is that the Low Salinity Zone (LSZ, 500-10,000 EC1) so critical to the Delta ecology has yet to be flushed west, out of the Delta. Turning up the pumps has actually increased the concentration of salt in export water (Figure 2) by pulling LSZ water from the north and west into the central and south Delta (Figure 3). Smelt and salmon concentrate in this zone. The LSZ has moved west from Rio Vista in the north Delta on the Sacramento River (Figure 4), but not from the west and central Delta on the San Joaquin side (Figure 5). Export pumps in the south Delta are pulling LSZ waters from the San Joaquin channel through False River and Dutch Slough (Figure 6).

Remnants of the Delta smelt population are in the central Delta.2 Winter Run salmon smolts began showing up at the export fish facilities in Clifton Court on 12/23. Both occurrences should be a stern warning, given the present poor state of these two endangered fish populations. Closure of the Delta Cross Channel earlier in December to protect migrating salmon actually aggravated the problem by limiting flushing of the central and west Delta and by trapping salmon and smelt in the central Delta. Exports should not be increased until the LSZ is west of Jersey Point. The Delta Cross Channel should remain open until the LSZ is west of Jersey Point. It is better for everyone if exports are pumping fresh water (

Graph of Delta outflow 2015

Figure 1. Delta outflow in December 2015.

Graph showing Electrical Conductivity at Clifton Court

Figure 2. EC of water exported from Clifton Court Forebay in south Delta in December 2015.

Map of flows

Figure 3. Aerial photo of Delta showing high Delta freshwater inflow and outflow from Sacramento River (blue arrow) and South Delta exports pulling brackish Low Salinity Zone water from central and west Delta San Joaquin channel to south Delta export pumps at Clifton Court Forebay (center bottom). The two eastward red arrows represent the False River (upper arrow) and Dutch Slough connections.

Graph of electrical conductivity at Rio Vista

Figure 4. EC at Rio Vista in north Delta on Sacramento River 12/19-12/26, 2015.

Graph of electrical conductivity at Jersey Point

Figure 5. EC at Jersey Point in the western Delta on San Joaquin River 12/19-12/26, 2015.

Graph of electrical conductivity at Dutch Slough

Figure 6. EC at Dutch Slough between the west and central Delta 12/19-12/26 2015. Note spike on 12/23 when south Delta exports were increased to 4000 cfs.

  1. EC is electrical conductivity expressed as microsiemens
  2. http://calsport.org/fisheriesblog/?p=570

NMFS on Salmon and the Drought, Part 2

As noted in the first blog of this series, the National Marine Fisheries Service (NMFS) is responsible under the Endangered Species Act for protecting the endangered Winter Run Chinook salmon of the Sacramento River. But when the US Bureau of Reclamation (USBR or Bureau) and the Department of Water Resources (DWR) have asked NMFS to comment on proposed changes in Central Valley Project operations during the present four-year drought, NMFS has consistently concurred, often going against its own previous prescriptions and advice. As a consequence, the Winter Run salmon were put at great risk, decimating the 2014 and 2015 year classes and again placing the population at the brink of extinction.

April 8, 2014 Drought Operations Plan

On April 8, 2014, the Bureau and DWR issued a 2014 Drought Operations Plan, in which they proposed low releases in the Sacramento River in April and May:

Keswick releases will be held to no greater than 3,250 cfs, or as determined necessary to reasonably target no more than 4,000 cfs at Wilkins Slough, unless necessary to meet nondiscretionary obligations or legal requirements;

The critical phrase here is “nondiscretionary obligations.” It is the view of NMFS, as described in its Biological Opinion for the Operation of the State Water Project and Central Valley Project, that the Bureau of Reclamation does not have the discretion to release less water to Sacramento River Settlement Contractors than 75% of contracted amounts. Thus, low April and May flows called for in the 2014 Drought Operations Plan were overwhelmed by calls for water by the Settlement Contractors.

April 8, 2014 NMFS Letter on Sacramento River Water Temperature Management

On April 8, 2014, NMFS wrote a letter1 to the Bureau and DWR in response to their April 8, 2014 Drought Operations Plan. In that letter, NMFS concurred with the Plan, but highlighted a concern regarding deliveries to the Settlement Contractors:

“Winter-run Chinook salmon viability and Sacramento Settlement Contractor deliveries: Reclamation is working with Sacramento River Settlement Contractors on options to shift a significant portion of their diversions this year out of the April and May period and into the time frame where Keswick releases are higher to achieve temperature objectives on the upper Sacramento River. The willingness and cooperation of the settlement contractors in this effort would allow a modified diversion pattern and create the benefit of increased Shasta Reservoir storage at the beginning of the temperature control operations and increased availability of water to these senior water rights holders in this critically-dry year. This deferral of irrigation would allow implementation closer to the lower range of the Keswick release schedule for April and May, as identified in Section V of the DOP (Drought Operations Plan).

Thus the agencies and the Settlement Contractors were left to work out on a voluntary basis a mechanism to keep enough cold water in Lake Shasta to protect Winter Run salmon throughout the summer and fall. The State Water Board approved the Plan.

It didn’t work. Though releases from Shasta in April, 2014 were low, the Bureau ramped up releases from Shasta to the Settlement Contractors in early May (Figures 1 and 2), and cold water in Lake Shasta was depleted by the end of August.

Graph of May 2014 releases from Keswick

Figure 1. May 2014 releases from Keswick to the Settlement Contractors were far above those advised by NMFS (

Graph of releases May 2014

Figure 2. May 2014 releases from Keswick to the Sacramento River were diverted by Settlement Contractors upstream of the Delta. Contrast flow at Wilkins Slough (~25 miles north of Woodland) with releases from Keswick in Figure 1: most flow increases over the month were diverted north of the Delta.

January 29, 2015 Letter on Sacramento River Water Temperature Management

On January 29, 2015, NMFS wrote a letter to the Bureau and DWR in response to a new January Temporary Urgency Change Petition (TUCP) to the State Board.2 In its January 29, 2015 letter, NMFS’s acknowledged lessons from 2014 regarding water temperature:

Temperature management is critical. Salmon rely on cold water, particularly during early life stages when fish are young and vulnerable. Shasta and Keswick dams block endangered winter-run Chinook from accessing their native cold water habitat in the Upper Sacramento and McCloud Rivers, so their eggs and fry are particularly vulnerable to high summer temperatures. Data from the Sacramento River indicate 2014 temperatures were at levels that impact the survival of juvenile salmon and steelhead. We found that the 2014 temperature criterion was exceeded starting in August, resulting in approximately 95% mortality of eggs and fry upstream of Red Bluff Diversion Dam. As of December 16, 2014, an estimated 390,000 juvenile winter-run Chinook salmon passed Red Bluff, compared to 1.8 million in the previous brood year and 850,000 in brood year 2011, the year of the winter-run collapse (see Nov. 18 USFWS/CDFW/NOAA Fisheries presentation to State Water Board). This is the fewest winter-run Chinook juveniles per female spawner passing Red Bluff in 11 years.

March 27, 2015 Letter

However, by the end of March, 2015, NMFS was once again tiptoeing through a proposal by the Bureau to repeat the previous year’s disaster. On March 27, 2015 NMFS once again concurred with the proposed TUCP, even while highlighting the “conflict” between Winter Run salmon and deliveries to the Settlement Contractors. 3

The Project Description meets all of the required aspects of the contingency plan required in Action I.2.3 .C, as follows:

  • Reclamation has provided an assessment of additional technological or operational measures that can increase the ability to manage the cold water pool.
  • Reclamation notified the State Board, through filing the TUC Petition, that meeting the biological needs of winter-run and the needs of resident species in the Delta, delivery of water to nondiscretionary Sacramento Settlement Contractors, and Delta outflow requirements per D-1641 , may be in conflict in the coming season.
  • In conclusion, NMFS concurs that Reclamation’s Project Description is consistent with Action I.2.3.C and meets the specified criteria for a contingency plan. … Furthermore, the best available scientific and commercial data indicate that implementation of the interim contingency plan will not exceed levels of take anticipated for implementation of the RPA specified in the CVP/SWP Opinion.

And once again in 2015, no one stepped up to maintain cold water in Shasta Reservoir in April and May (Figure 3).

Graph of 2015 releases

Figure 3. In 2015, releases to the Settlement Contractors ramped up in April and were high throughout May.

July 1 Letter4

By July 1, 2015, NMFS was already issuing a post-mortem.

“NMFS acknowledges that storage in Shasta Reservoir at the beginning of the temperature management season in June, and the quantity and quality of the cold water pool, will not provide for suitable winter-run habitat needs throughout their egg and alevin incubation and fry rearing periods.”

Final Comment

We should expect more from the federal agency mandated to protect our endangered salmon. At a minimum, NMFS should have not concurred, in 2015 (or in 2014, for that matter), and should have called out the fact that added take of Winter Run would occur, further jeopardizing the viability of the species through direct mortality and degradation of their critical habitat.

Regardless of the legal merit of NMFS’s position that it does not have authority under the Endangered Act to limit deliveries to the Settlement Contractors, its failure to defend listed Winter Run gave cover to the Agency that has that authority: the State Water Board. CSPA, the Bay Institute and others asked the State Water Board in February, 2015 and again in the spring to reduce 2015 deliveries to the Sacramento Valley Settlement Contractors to save the Winter Run (and to protect Delta smelt). In an Order denying Petitions for Reconsideration of the 2015 TUCP’s filed by CSPA and others, the State Water Board offered the rationale:

However, at the time the changes were approved, the tradeoff appeared to be reasonable based on the information available at the time, including biological reviews from DWR and Reclamation and concurrence from the National Marine Fisheries Service (NMFS), U.S. Fish and Wildlife Service (USFWS), and California Department of Fish and Wildlife (DFW) (collectively fisheries agencies) with the changes. For these reasons, the petitions for reconsideration of the past Executive Director actions are denied. 5