It is Fall X2 Time Again

Posted on September 4, 2019 by Tom Cannon

The 2008 Delta Smelt Biological Opinion for Central Valley Project (CVP) and State Water Project (SWP) includes the Fall X2 provision to keep brackish water west of the Delta through October in wet years to protect Delta smelt. X2 or the low salinity zone is defined as the location where salinity is 2 parts per thousand (about 4000 EC). Keeping X2 at Chipps Island (km 71 from the Golden Gate) benefits the longfin smelt and Delta smelt populations. In wet years, the smelt are protected by Delta agriculture salinity standards through August 15. The Fall X2 provision keeps X2 and the smelt west of the Delta through October.

This is the third wet year since 2008 (the others were 2011 and 2017) in which the provision for X2 in the Biological Opinion has applied. When I last posted about the 2017 implementation, I remarked that the US Bureau of Reclamation had requested not to apply the provision because of the high cost of water and minimal benefit to the smelt populations. In the end, the provision was applied, but in an unusual way that likely had some new negative consequences on smelt and their Bay-Delta critical habitats.

Reclamation has again requested exemption from the provision in wet year 2019. Again, Reclamation referenced the high cost of water and minimal benefits to smelt, despite unequivocal evidence that smelt benefit (Figures 1 and 2).

The Fall X2 flows are being applied with extra releases from Shasta, Oroville, Folsom, and New Melones reservoirs (Figure 3). Without the X2 requirement that is creating inflows to the Delta of about 25,000 cfs, Delta inflow would only need to be 15,000 cfs to meet 65% export-to-inflow requirement. With lower reservoir releases, river flows and Delta outflows would be lower at the discretion of Reclamation. In the past, Reclamation has also failed on many occasions to meet water temperature standards in the lower Sacramento River and the American River, as well as south Delta salinity standards.

Application of the Fall X2 provision benefits smelt and the fall upstream migration of salmon in the Sacramento and San Joaquin rivers and their tributaries. In Suisun Bay and the western Delta, salinities and water temperatures would be higher without Fall X2 (Figures 4-6). Fall X2 application also helps maintain the water temperature requirements in Reclamation’s water right permits and the water quality standards in the lower Sacramento River between Red Bluff and the Delta.

Figure 1. Delta smelt spawner-recruit relationship. Note strong recovery in 2011. Source: http://calsport.org/fisheriesblog/?p=1966

Figure 3. Bay-Delta hydrodynamics in late August 2019 under Fall X2 operations. Flows are average daily cfs. South Delta exports are in red. Red circle is location of X2.

Figure 2. Longfin smelt spawner-recruit relationship. Source: http://calsport.org/fisheriesblog/?p=2513

Figure 4. Water temperature and salinity (EC) in eastern Suisun Bay, August 1, 2017 through November 1, 2018. Fall X2 was applied in 2017 (red outlined box). Note lower salinity and lower water temperature in 2017 compared to 2018.

Figure 5. Water temperature and salinity (EC) in the lower Sacramento River channel of the west Delta near Decker Island August 1, 2016 through November 1, 2018. Fall X2 was applied in August-September 2017 (red outlined box). Note lower salinity and slightly lower water temperature in 2017 during Fall X2 application compared to 2016 and 2018 without Fall X2.

Figure 6. Water temperature and salinity (EC) in the lower San Joaquin River channels near Jersey Point in the western Delta from August 1, 2016 through November 1, 2018. Fall X2 was applied in August-September 2017 (red outlined box). Note lower salinity and slightly lower water temperature in 2017 during Fall X2 application compared to 2016 and 2018 without Fall X2.

Delta August Adjustment

Posted on August 12, 2019 by Tom Cannon

The State of California has markedly increased inflows to the Delta and reduced exports in early August 2019 (Figure 1). There is no announced reason for this major hydrologic adjustment that has had a major effect on Bay-Delta habitat. The likely reason was to maintain the 14-day average salinity standard of 450 EC at Jersey Point,¹ which was exceeded on a daily basis beginning on August 10 (Figure 2).

“Adjustments” to Delta inflow and exports began at the end of July as daily Jersey Point salinity began to exceed the 450 EC standard. The federal Central Valley Project made little or no contribution to this correction.

These recent changes are a textbook example of why the 14-day salinity standard needs to change to a daily standard. State water managers gamed easily controlled parameters, using the 14-day average to squeeze out more exports through July. This operation caused a major system reaction with far-reaching consequences to the State Water Project system and to the Bay and Delta.

The state could have maintained a daily 450 EC limit with gradual small system adjustments and support from the CVP.

Further discussion of the effects follows below.

Figure 1. Sacramento River Delta inflow at Freeport (FPT flow), Delta outflow (DTO resflow), state exports (HRO pumping), and federal exports (TRP pumping), 7/1-8/9, 2019. Note only state exports were affected.

Figure 2. Salinity (EC) at Jersey Point near mouth of San Joaquin River in the Delta 7/14-8/10, 2019.

Delta Inflow
Sacramento River inflow to the Delta at Freeport increased about 3000 cfs to just over 20,000 cfs (Figure 3). The extra flow came from the Feather River (Oroville Reservoir of the SWP). The higher inflow coincided with a drop in water temperature at Freeport from 23^oC to 21^oC.

Delta Outflow
Delta outflow rose about 9000 cfs from near 7000 cfs to 16,000 cfs (3000 from inflow and 6000 from reduced exports, Figure 1). Outflows rose in the Sacramento channel at Rio Vista (Figure 4) and San Joaquin channel (Figure 5). Water temperatures also fell about 1^oC.

Interior Delta
Flow also increased and water temperature fell in Georgianna Slough (Figure 6).

Suisun Bay
Salinity and water temperature fell in Suisun Bay west of the Delta (Figure 7).

Figure 3. Flow and water temperature in Sacramento River at Freeport 7/1-8/10, 2019.

Figure 4. Flow and water temperature in Sacramento River at Rio Vista, 7/1-8/10, 2019.

Figure 5. Flow and water temperature in San Joaquin River at Jersey Pt, 7/1-8/10, 2019.

Figure 6. Flow and water temperature in Georgianna Slough in the central Delta, 7/1-8/10, 2019.

Figure 7. Salinity and water temperature in Suisun Bay near Pittsburg, 7/1-8/10, 2019.

The standard applies for wet years through August 15. ↩

Delta June 2019

Posted on July 19, 2019 by Tom Cannon

Water year 2019 has been a very wet year. Yet salmon and sturgeon survival was compromised by low flows and high water temperatures in the Sacramento River this spring.¹ Young salmon survival has been further compromised by low flows, high exports, and high water temperatures in the Delta this past June.

Many of the wild smolts produced in Central Valley rivers this year entered the Delta in May and left (or died) by the end of June, as observed in Delta export salvage collections (Figure 1). Many of the wild smolts captured in the south Delta likely originated from San Joaquin tributaries. South Delta exports were near maximum at 10,000 cfs, about 70-80% of San Joaquin inflow to the Delta and 20% of total Delta inflow. The high exports caused lower flows and associated high water temperatures (>20^oC) in the Delta channel of the lower San Joaquin River (Figure 2), and contributed to similarly high temperatures in the lower Sacramento River channel (Figure 3).

The high Delta water temperatures (>20^oC) compromised the survival of the salmon smolts in June. Reducing the export limit to 5000-6000 cfs in June of this wet year would have kept the water temperature near a 20^oC limit. The water quality standards in the 1980’s and 1990’s under D-1485 had a 6,000 cfs June export limit. In the past two decades under D-1641, the June export limit changed to 65% of total inflow.

New Delta water quality standards should provide export limits and inflow/outflow minimums that protect salmon through the spring months.

Figure 1. Chinook salmon salvage at south Delta export facilities in 2019. Note the prevalence of wild (non-hatchery) smolts in May-June.

Figure 2. Water temperature and tidally-filtered flow at Jersey Point in the lower San Joaquin River channel of the Delta in June 2019.

Figure 3. Water temperature and tidally-filtered flow at Rio Vista in the lower Sacramento River channel of the Delta in June 2019.

http://calsport.org/fisheriesblog/?p=2673 ↩

Sacramento River Salmon Opener Compromised

Posted on July 13, 2019 by Tom Cannon

The California Department of Fish and Wildlife announced in May that the salmon season on the Sacramento River would commence below Red Bluff on July 16, with high expectations and expanded limits.

“California’s inland salmon anglers can look forward to a better salmon fishing season than last year. A projected return of 379,600 spawning Sacramento River fall-run Chinook Salmon to Central Valley rivers has allowed fishery managers to return to a two salmon daily limit with four salmon in possession. This is a welcome increase over last year’s regulations, which restricted anglers to one salmon per day and two in possession.”

Yet despite near record water and a full Shasta Reservoir, the federal government is compromising the run with high water temperatures from low reservoir releases and high river diversions that violate state water quality regulations and water right permit requirements.

River flow near Red Bluff is just above 12,000 cfs (Figure 1), about 1000 cfs below average for this time of year. River flow in the river a hundred miles downstream, upstream of the mouth of the Feather River, is just below 7000 cfs, also slightly below average (Figure 2). The flow difference between the two locations reflects water deliveries to federal water contractors near 5000 cfs.

The high diversions and low flows result in high water temperatures in the lower river (Figure 3) that will compromise the fishery opener as well as survival and egg production of this fall’s spawning run. The salmon run is already in a long-term decline (Figure 4) from poor water management and violations of standards and permits conditions.

Why allow the federal government to squeeze out more of California’s precious water and salmon? Increasing Shasta releases or reducing diversions, or a combination thereof, by about 1000-2000 cfs should protect the migrating salmon and provide a better fishery opener. With triple-digit weather forecasted for the latter half of July, it is imperative that river flows be increased.

Figure 1. Sacramento River flow near Red Bluff June-July 2019.

Figure 2. Sacramento River flow near Grimes at Wilkins Slough June-July 2019.

Figure 3. Sacramento River water temperature below Wilkins Slough June-July 2019. Note that water quality standard is 68oF, above which salmon become stressed.

Figure 4. Sacramento River fall-run salmon escapement 1952-2018.

Why is Water Temperature in the Delta so important? Why there should be a water quality objective in the Delta for water temperature.

Posted on June 25, 2019 by Tom Cannon

The rivers flowing into the Delta are generally cool. The Bay is generally cool. But the Delta gets warm (>20^oC, 68^oF) from late spring into early fall. Rivers have a water quality standard limit of 68^oF.¹ The Delta should too.

Salmon, smelt, and steelhead are cool water fish that use the Delta for major portions of their life cycle. Water temperatures above 68^oF are stressful, leading to poorer growth, higher predation, lower survival, and early exits from Delta critical habitats. One reason for the stress is that warmer water holds less dissolved oxygen. When water temperature exceeds 68^oF, dissolved oxygen falls below 8 parts per thousand (ppt), which is stressful to fish. In eutrophic (high organic loads with lots of aquatic plants) waters like the Delta, dissolved oxygen can get even lower, near the minimum state standards (6-7ppt), especially at night.

Delta waters are cooler in wet years because of higher flows and generally cooler spring air temperatures. There is no doubt that low river inflows, higher exports, and low Delta outflows can exacerbate high Delta water temperatures, especially during hot periods of summer. There is also plenty of evidence that higher inflows, lower exports, and higher outflows during exceptionally warm weather can help minimize high water temperatures.

Delta waters are cooler when inflows are higher and cooler. The lower reaches of rivers that enter the Delta are cooler with higher flows. Maintaining high river inflows with the associated cooler water helps maintain Delta water temperatures. It takes approximately 20,000 cfs of Sacramento River inflow at Freeport to the Delta to maintain inflow water temperature near 68^oF in summer (Figures 1-3).

The central Delta flow inputs are also cooler in late spring under higher Delta inflows, as exemplified by water temperature and flow comparisons between dry 2015 and wet 2011, 2017, and 2019 (Figures 4 and 5). This comparison dispels the argument that that water temperature in the Delta is wholly dependent on air temperature and is not affected by flow.

There is evidence that increasing diversions and decreasing flows in warmer weather (Figures 1 and 3) increases water temperatures. This is another reason to increase Delta river inflows during warm weather. A Delta water temperature standard/objective would potentially require episodic higher Delta inflows to offset higher warm weather diversions, in addition to a sustained inflow near 20,000 cfs in summer.