Summer Delta Salinity Standards: 2018 Example

Posted on December 29, 2018 by Tom Cannon

In a July 2016 post I recommended a 500 EC (electroconductivity) salinity standard from July-to-mid-August for the western Delta. The longstanding Water Rights Decision 1641 standard includes this only in Wet years. It should apply in all year types unless south Delta exports are at minimum levels.

In summer 2018, a Below Normal, subnormal snowmelt year, Jersey Point salinity was kept near 500 EC through early August (Figure 1) instead of the allowed 740 EC. Was this an adaptive management experiment? If so what benefits were derived from the experiment?

Figure 1. Jersey Point salinity (EC) remained near 500 EC in early summer 2018. The applicable standard was 740 EC 14-day average through August 15.

Benefit #1:
The water temperature in the west Delta in 2018 was kept near 73°F or below (Figure 2), a good thing. In 2016, the previous Below Normal year, EC was allowed above 500 EC (Figure 3) per the existing standard. Water temperature exceeded 73°F to near 75°F (Figure 4), a bad thing, when EC exceeded 500. The reason for the higher early summer 2016 EC and warmer water temperatures was low Delta outflow (Figure 5). Outflow in 2016 was about 7000 cfs, but needed to be near 8000-9000 cfs. In 2018, outflow in late June was 7500-7900 cfs (Figure 6), in part due to relatively low early summer Delta exports (Figure 7) compared with 2016 (Figure 8).

Other Benefits:
It is really too bad that we can no longer look to Delta smelt for response to adaptive management. But I suspect positive response to the 2018 “experiment” occurred in survival of other juvenile Delta fish (e.g., striped bass), shrimp, zooplankton, and phytoplankton. When 2018 data become available, the comparison with 2016 and prior years can be made.

Conclusion:
The salinity standard for the west Delta at Jersey Point and Emmaton should be 500 EC daily average unless south Delta exports are restricted to minimum health and safety levels. The standard should be year-round in all year types. Delta exports should be restricted to the minimum unless the salinity standard is met.

Figure 2. Water temperature at Jersey Point in west Delta summer 2018.

Figure 3. Jersey Point salinity EC summer 2016. Standard was 740 EC 14-day average through August 15.

Figure 4. Water temperature at Jersey Point in west Delta summer 2016.

Figure 5. Delta outflow in summer 2016.

Figure 6. Delta outflow in summer 2018.

Figure 7. State exports from south Delta summer 2018.

Figure 8. State exports from south Delta summer 2016.

No Delta Smelt Fall 2018

Posted on December 12, 2018 by admin

Though I hate to “beat a dead horse” or perhaps more appropriately “put another nail in the coffin,” I’m sad to report that the California Department of Fish and Wildlife’s first two fall trawl surveys for 2018 collected no Delta Smelt. This is consistent with this past summer’s townet survey results. Let’s get on with implementing the smelt hatchery program.

Fall mid-water trawl survey catch for September and October 2008-2018. Data source: http://www.dfg.ca.gov/delta/data/fmwt/indices.asp

Solving the Delta’s Invasive Aquatic Vegetation Problem

Posted on December 5, 2018 by Tom Cannon

A recent science paper reminded me about the benefits of aquatic vegetation to lake fish species like largemouth bass. It also reminded me that invasive aquatic vegetation has ruined lake-like salmon habitats of the west coast, such as Seattle’s Lake Washington and portions of the Columbia River and California’s Bay-Delta estuaries. Instead of rearing salmon and smelt, these waters now rear non-native bass and sunfish (centrarchids). These once-turbid waters conducive to rearing juvenile salmon and smelt are now best suited for sight-feeding centrarchids, competitors and predators of salmon that love clear water and abundant cover. The non-native aquatic vegetation (Egeria, hyacinth, and milfoils) in the Bay-Delta provides abundant cover, uses all the aquatic plant nutrients, and collects the suspended sediment – all bad for the Bay-Delta’s pelagic/planktonic habitat.

Other than gripe about the obvious problem over the past several decades, what has anyone done about it? Boating and Waterways has tried spraying herbicides, but that has been costly, ineffective, messy, and organically/chemically polluting. Flushing the Delta all year with more-and-more clear reservoir water to south-Delta export pumps has not helped. The proliferation of non-native clams has also contributed to the problem.

There are no easy solutions, but there are options that should be implemented. Though costly and with their own environmental problems, these options can potentially lead toward recovery of the most important Delta habitats. The best option is an aggressive (and expensive) long-term program of manual cutting and harvesting using boat‐mounted cutters, harvesting barges, and suction dredges to remove the rooted and floating aquatic plants. A longer-term option is to increase turbidity from inorganic and organic sources by adding silts or reducing silt “sinks;” this would help cut sunlight and nutrients to rooted aquatic plants. Direct application of aquatic fertilizers has recently been considered by resource agencies; this could also help. Finally, reducing exports from the south Delta could help because it would reduce the proportion of low-turbidity reservoir water in the Delta and lessen the direct loss of millions of tons of silt.

Shifting the Bay-Delta habitat away from centrarchids by increasing Delta turbidity will measurably improve salmon and smelt recovery.

Central Valley Spring Run Salmon – Record Low Run

Posted on November 14, 2018 by Tom Cannon

In a 10/31/17 post, I described record low spring-run Chinook salmon runs in Sacramento Valley rivers in 2017, with emphasis on the Feather River, the largest component of the Central Valley spring-run population. In this post, I update information on Central Valley spring-run. The combined Central Valley runs of spring Chinook salmon were indeed at record low levels in 2017 (Figure 1). The run total includes escapement to all Central Valley streams that host spring-run salmon, including Battle Creek, Clear Creek, Butte Creek, Antelope Creek, Big Chico Creek, Cottonwood Creek, Mill Creek, Deer Creek, Antelope Creek, Feather River-Yuba River, and the mainstem Sacramento River.¹

I plotted these numbers in a spawner-recruit relationship, with spawners being recruits three years earlier (Figure 2). The water year type during the first winter-spring following spawning is shown in Figure 2 by color. Winter-spring conditions reflect early rearing and emigration conditions in spawning rivers, as well as conditions in rivers downstream an in the Bay-Delta.

Factors contributing to poor recruitment in the eight critically dry years in the observed period include low river flows, high water temperatures, excessive predation, loss at water diversions, and low turbidity, all factors that are inter-related. Poor ocean conditions and hatchery operations also were likely factors, which may also be related directly or indirectly to river flows.

Most recent recovery efforts and planning have focused on habitat restoration.² My own focus has been on poor river conditions (low flows and high water temperatures) and related predation.³ My reasoning is based on escapement trends over the past decade that indicate sharply dropping escapement during dry year low-flow conditions in most of the spawning rivers (Figures 3-5).

Figure 1. Spring run salmon in-river escapement (spawning run size) in the Central Valley from 1975 to 2017.

Figure 2. Spawner-recruit relationship for Central Valley river escapement of spring-run Chinook salmon. Recruits represent spawner escapement for that year. Spawners are recruits from three years prior. Numbers are log10 of escapement minus three. Red represents dry years during winter-spring after fall spawn. Blue represents wet years. Green represents normal years. Blue dotted line is statistical trend line. Yellow line is replacement level. Note eight points in bottom-right quadrant represent winter-springs of critically dry drought years (77, 89-91, 07-08, 13, and 15).

Figure 3. Battle Creek spring run salmon escapement from 1989 to 2017.

Figure 4. Deer Creek spring run salmon escapement from 1975 to 2017.

Figure 5. Mill Creek spring run salmon escapement from 1975 to 2017.

Lower Sacramento River Water Temperatures A 5-Year Adaptive Management Study of Lower Sacramento Summer Flows and Water Temperatures

Posted on September 18, 2018 by Tom Cannon

Nearly three decades ago, state and federal regulators made prescriptions that required the maintenance of water temperatures in the lower Sacramento River below 68^oF (20^oC) in summer to protect salmon, sturgeon, steelhead, and water quality. The condition was put in water right permits, anadromous fish restoration plans, and in the state’s water quality plan for the basin. Summer is the season when once-abundant spring, fall, and winter run salmon ran up the river and to tributaries to spawn. It is also the rearing season for spring-spawning sturgeon, striped bass, American shad, splittail, and trout, all once abundant in the lower Sacramento River watershed.

The effect of how the prescription was administered in the early 1990’s can be seen in water temperature record for Wilkins Slough in the lower Sacramento River near Grimes (Figure 1). The gradual erosion in the application of the prescription is also apparent over the past two decades. Lack of enforcement of the prescription by federal and state regulating agencies in the last five years is also apparent even in the recent wetter years following the critical drought years of 2013-2015.

I looked at the last five years, 2014-2018, as an adaptive management study to determine how to maintain the 68^oF prescription. Plots of water temperatures and river flow from Wilkins Slough (Figures 2-6) are unequivocal evidence that river flow is the primary driver of summer water temperatures in the lower Sacramento River near Wilkins Slough. Air temperature is a lesser factor in summer because it is nearly always warm. A rise in flow over the summer of 2018 (Figure 6) shows clearly that keeping flows in the 6000-8000 cfs range (depending on air temperature) can maintain water temperature near the 68^oF target. Flows in the 3000-5000 cfs range lead to water temperatures of 72^oF or higher, which are very detrimental to the dependent fish.

Finally, the gradual decline in summer river flow at Wilkins Slough over the past two decades (Figure 7) matches the rise in summer temperatures (Figure 1). It is not a question of changing water quality standards to protect fish. It is simply a question of enforcing the existing standards and water right permit requirements. Increasing Shasta Reservoir releases, limiting water diversions, or some combination thereof, could provide the necessary flows.