Author Archives: Tom Cannon

A Ridiculous Premise

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A recent post from the Center for California Water Resources Policy and Management (Center) discusses the extinction of the Delta smelt.  The post starts by saying, “To be sure, the delta smelt’s numbers are in decline.”  That is a real understatement, but it contains some acknowledgement of the facts.

The author goes on to say, “It might fairly be argued that prime contributors to the delta smelt’s distressed status are California’s resource agencies.”  The ostensible rationale for this attribution is, first, that the resource agencies don’t look for smelt in the right places in the right way.  Second, because the agencies can’t find the smelt, “they have resisted managing the species ‘adaptively’” based on the monitoring that they don’t do.

This ridiculous premise suggests the decline has not been caused by excessive exports of water from the Bay-Delta watershed over the past five decades, but by the resource agencies who don’t know where to find and thus protect the smelt.

The author argues: “The agencies persist in mobilizing trawler-based open-water fish surveys, originally intended to census juvenile striped bass, as their primary means of monitoring delta smelt and the Delta’s other protected fish species.”  This statement is simply untrue.  To provide better coverage of “open-water” pelagic smelt, the Interagency Ecological Program (IEP) in recent decades added the Larval Survey, the 20-mm Survey, the Kodiak Trawl Survey, and most recently the Enhanced Delta Smelt Monitoring Program (EDSM).   All of these surveys, plus the historic Fall Midwater Trawl and Summer Townet Surveys (and 50 years of Delta Export Fish Salvage Surveys), show the smelt’s catastrophic decline and march toward extinction.

But the author insists that the smelt are out there somewhere.  “The surveys sample neither the relevant habitat strata used by those fishes nor the extent of their ‘closed’ populations, which would allow for estimates of the sizes of their populations.”  If the smelt are out there in “closed populations” whose numbers would change the conclusions about the smelt’s catastrophic downward trend, then surely the author and the water purveyors who have a vested interest in finding those populations can muster some evidence and show the agencies and the rest of the world where to look.

Basic review and analyses of the available information show the decline of Delta smelt is highly associated with increasing exports and associated factors (see my many posts on this subject).  The partial truth in the notion that the resource agencies have been complicit in the decline of Delta smelt stems from agency inaction to cut back those exports consistent with biological sustainability.  Agency managers don’t lack information and scientific method.  They lack the political courage to deploy them.

Lake Shasta – Late Fall 2021

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When I first moved to California in fall 1977, I camped at Lakehead on Lake Shasta. I was surprised to only find the Sacramento River. I got the same view on a recent visit (Figures 1 and 2). No black bass or channel catfish, and few trout. The lake is down nearly 200 feet from when it last filled in spring 2019 (Figure 3). Storage is at 25% capacity (Figure 4). Flows were high from recent storms. The “river” was cutting into decades of deposited sediment, making what remained of the lake very turbid. Not the greatest conditions for my favorite fall fishery for spotted bass and trout.

Figure 1. Mid-November 2021 photo of Sacramento River arm of Lake Shasta. Note river cutting through historic lake sediments.

Figure 2. Mid-November 2021 photo of Sacramento River arm of Lake Shasta. Note “cuts” in lake sediment and turbid water.

Figure 3. Water surface elevation in Lake Shasta 2019-2021.

Figure 4. Current and historical water-year conditions for Lake Shasta storage.

More on the Delta Threat to Winter-Run Salmon – Fall 2021

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During early November, juvenile winter-run salmon were moving into the Delta after two short fall rainfall pulses (Figure 1). The allowed export of 65% of Delta inflow is not protective of these wild young winter-run salmon, which are in short supply this year. My October 30 post, in which I warned about the threat of rising Delta exports on this year’s production of juvenile winter-run salmon entering the Delta, is being borne out.

From November 9-12, south Delta exports exceeded 70% of Delta inflow,1 with about 2000 cfs of calculated Delta outflow. The USGS measurement of Delta outflow on November 8-9 was as low as -3000 cfs. Delta exports were simply drawing from the Delta’s freshwater reservoir supplied by the recent rains. The cries of San Joaquin Valley farmers for the capture of the runoff before it was “wasted” into the Bay and Ocean were indeed being answered. The Delta export pumps were shipping 15,000-20,000 acre-feet of water south each day.

Up at the Delta Cross Channel (open) and Georgianna Slough, over half the daily flow was being diverted into the central Delta. With the False River Barrier installed, most of the diverted water (and young salmon) flowed south toward the export pumps. Since no young salmon were showing up in the export fish salvage collections, it is likely that few successfully made the 50-mile journey from the northern Delta through the predator-laden central Delta corridor.

Hopefully, the several hundred thousand winter-run hatchery smolts will have better circumstances when they are released this winter near Redding for their 300-mile migration to the ocean.

Figure 1. Capture of juvenile winter run salmon in the lower Sacramento River in 2021.

Another Threat to Winter-Run Salmon in 2021 – Fall Sacramento River Bypass Overflows

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Record late-October Valley rainfall brought Sacramento River flows high enough to overflow into the Tisdale Bypass (Figures 1 and 2).  Such early-fall overflows are highly unusual (Figure 3). The sudden surge filled nearly 30 square miles of the Sutter Bypass before exiting to the south, back to the Sacramento River (Figure 4).  Bypass channels rose 6-10 feet during the storm, with the help of tributary inflows (CDEC gage data not shown), flooding much of the agricultural fields, levee borrow pits, duck club ponds, and natural wetlands and ponds of the Sutter Bypass.

Riding the wave of river flow were juvenile winter-run salmon moving down the Sacramento River (Figure 5).  Many spilled over the weir into the Bypass and into flooded habitats.

After the storms, a sudden drop in flow quickly drained the Sutter Bypass, and many juvenile salmon became stranded in ponds and fields of the Bypass floodplain.  The problem with the short-lived early fall flooding is that stranded habitats dry up or become too warm too sustain the young salmon through the fall, winter, or even spring (if the Bypass does not flood again).  Predation by abundant non-native predatory fish in the Bypass is another problem, especially as the high flows of muddy water retreat.

Also at issue is the attraction of upstream migrant adult fall run-salmon into the Bypass.  Such salmon get trapped downstream of the Tisdale Weir.  The Tisdale Weir Rehabilitation and Fish Passage Project is supposed to mitigate this situation.  But it is only in the planning and design stages, and until that project is complete, adult salmon will continue to be trapped below Tisdale Weir.  In addition, the Tisdale Weir project “does not analyze the impacts to additional special status fish (juvenile salmonids) being attracted into bypass from extended days of inundation and subsequently being stranded without adequate drainage or a plan to mitigate for that.” (Project EIR).  The Tisdale Weir project also needs to plan for and mitigate the juvenile stranding in the Sutter Bypass.

Until the Tisdale Weir Project addresses these issues, fall spills into the Sutter Bypass from flood control weirs on the Sacramento River will reduce survival of winter-run salmon and other anadromous salmonids of the Sacramento River and its tributaries.

Figure 1. The Tisdale Weir and Bypass from the Sacramento River to the Sutter flood bypass.

Figure 2. Overflow (cfs) into the Tisdale Bypass from the Sacramento River 10/24-26/2021. Data Source: CDEC.

Figure 3. Tisdale Weir overflows 1998-2019.

Figure 4. Sutter Bypass properties subject to flooding from Tisdale Weir overflow.

Figure 5. Juvenile salmon collection in screw traps in Sacramento River near Tisdale Weir Aug-Nov 2021.

 

 

Delta Smelt Status 2021

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The Enhanced Delta Smelt Monitoring (EDSM) caught only 1 Delta smelt in 2200 smelt-targeted net tows in 2021.  This compares to 49 captured in 2020 and hundreds in prior years.  None were captured in the Spring Kodiak Trawl 2021 survey (Figure 1).  This year’s results indicate that Delta smelt are likely virtually extinct in the wild.

Figure 1. Spring Kodiak Trawl survey index of Delta smelt (2004-2021), in which none were caught in 2021. Only one was captured in 2020. (source)