The Draft EIS for the Coordinated Long-Term Operation of the Central Valley Project and State Water Project¹ was released in July, and comments are due by the end of September. Projects analyzed in the EIS include the Shasta-Trinity Division of the Central Valley Project (CVP) (Figure 1). The EIS focuses on the human effects of the reasonable and prudent alternative (RPA) requirements in NMFS Biological Opinion on the two projects, including the Shasta-Trinity Division.

This is the first in a four-part series focusing on the operation of the CVP Shasta-Trinity Division on Sacramento, Trinity, and Klamath River salmon. Part 2 will focus specifically on Sacramento salmon with emphasis on the listed Winter Run Chinook. Part 3 will focus on effects of Klamath-Trinity salmon. Part 4 will focus on how the system can be better operated to save salmon in the two rivers. This Part 1 sets the stage for Parts 2 and 3.

In the past four years of drought, the track record of the Bureau of Reclamation has been poor in managing Shasta-Trinity reservoir storage, releases, and water temperatures to sustain salmon in Sacramento, Trinity, and Klamath Rivers. After reservoirs filled in the wet water year 2011, they were steadily drawn down in 2012 and 2013. By 2014, the reservoirs were dangerously low. On the Sacramento River in 2014, the system failed, and most of the Winter-Run brood year was lost to warm water and low flows in early September. As of the first week of September this year, the Shasta cold-water pool continues to contribute to the Sacramento, although water temperature standards were weakened through the summer at the request of Reclamation, causing some mortality after inaccurate spring predictions of cold-water storage in Shasta. On the Klamath and Trinity Rivers, the mass mortalities seen in 2002 were not seen in late summer 2014 and 2015 (so far) despite the presence of disease, because of emergency late summer cold-water flow increases from Trinity Reservoir that cooled the Trinity River and lower Klamath.

The Shasta-Trinity Division is a huge complicated system with associated difficulties in satisfying all the water contractors in the Central Valley while maintaining the salmon resources. Management for salmon boils down to the following set of parameters:

1. Reservoir storage (Figures 2 and 3)
2. The amount of cold-water pool in reservoir storage
3. The distribution of reservoir releases through power turbines (warmer) or lower level bypasses (colder)
4. The daily pattern of reservoir releases to meet peaking power demands for electricity
5. Blending capabilities in reservoir outlets to power turbines (Shasta has a Temperature Control Devise that allows Reclamation to pull water from different lake levels)
6. Water temperature mixing in the two re-regulating reservoirs (Keswick below Shasta and Lewiston below Trinity)
7. Water temperatures of releases to the Sacramento and Trinity Rivers
8. The export of Trinity Reservoir water via Lewiston and Whiskeytown reservoirs to Keswick Reservoir (to Sacramento River).
9. The magnitude and seasonal variability of Keswick and Lewiston releases to the Sacramento and Trinity rivers, respectively.
10. How much water is delivered (and thus, not delivered) to CVP contractors.

Figure 1. Shasta-Trinity Division of Central Valley Project

Figure 2. Shasta Reservoir storage in acre-ft from April 2012 to present.

Figure 3. Trinity Reservoir storage in acre-ft from April 2012 to present.

Minimum carryover storage for Trinity Reservoir is supposed to determine Trinity exports to the Sacramento River basin. In the driest years (certainly 2015 would be considered such a year), exports to the Sacramento are to be minimized to meet minimum instream flow and water temperature requirements on the Trinity River to save Klamath-Trinity salmon from mass die-offs as occurred in 2002¹. The low probability of refilling of Trinity Reservoir, as compared to Shasta Reservoir, necessitates the restriction. Yet this summer, three-quarters of the 2000-cfs of water being released from Trinity Reservoir is going to the Sacramento River. Low flows in the Trinity and lower Klamath are again threatening Klamath-Trinity salmon, resulting in Reclamation having to triple Trinity River flows as of August 22 (Figure 1). The added water is coming from the already-depleted Trinity Reservoir, while the 1500-cfs export to Sacramento Basin water users continues.

Figure 1. Trinity-Lewiston Reservoir releases to lower Trinity River in mid August 2015. Base required minimum flow is 450 cfs. Flow pulse from August 17-20 was for Hoopa tribal ceremony. New release (1150 cfs) to cool river commenced on August 21.

Reclamation tries to justify the transfer of Trinity water as needed to save Sacramento Winter Run Chinook salmon below Shasta Reservoir, when the transfer actually puts the Sacramento salmon at greater risk². The transfer water passes through Whiskeytown Reservoir, from which it is released to the Spring Creek Powerhouse to the Sacramento below Shasta. The 50°F water from the Trinity Reservoir cold-water pool transferred to Whiskeytown warms nearly 10 degrees (58.5-59.5°F) before passing through the Spring Creek Powerhouse on Keswick Reservoir. Water from Whiskeytown would be even warmer if not for a floating water curtain installed at the reservoir outlet in 2011 to reduce water temperature of releases to the Sacramento basin (Figure 2).³

Figure 2. Floating boom of water curtain in Whiskeytown Reservoir outlet cove to Spring Creek Powerhouse in Sacramento basin.

The 59°F water entering Keswick Reservoir must be cooled by Shasta 50°F cold-water pool water to meet the 54-56°F required release temperature of the 7000 cfs prescribed release of water into the Sacramento River above Redding. Because Shasta releases are a blend of cold and warm water to meet downstream required temperatures, the added burden of cooling the Trinity water adds to the demands on the critically low cold-water pool remaining in Shasta Reservoir.

The limited Shasta cold water pool has already resulted in the State Board’s weakening of the average daily water temperature standard of 56°F to protect Winter Run salmon eggs to 58°F at Redding. The weakened standard will result in some egg mortality. There remains concern whether the cold water pool releases can be sustained through the summer, unlike last summer when coldwater ran out in early September leading to the loss of 95% of the salmon production.

Further exacerbating the above problems is the continuing operation of all three storage reservoirs (Trinity, Whiskeytown, and Shasta) for peaking power (Figure 3). Releases for peak power demands occur during afternoon hours when reservoir waters are at their warmest (Figure 4). This specific operation pattern has lead to high afternoon water temperatures in Keswick releases to the Sacramento River, and most recently to higher night release temperatures (Figures 5 and 6). The standard remains 58°F average daily water temperature. Egg mortality increases above 56°F.

Figure 3. Release pattern at Shasta Dam in recent days. Peak releases to five powerhouses occurs in afternoon consistent with power demands. Note night releases having virtually been eliminated on August 23 in favor of daytime releases.

Figure 4. Temperature of water in penstocks to powerhouse from Shasta Reservoir. Note warmest water occurs during peak flows in afternoons.

Figure 5. Water temperature of water released from Keswick Dam to upper Sacramento River.

Figure 6. Water temperature of Sacramento River in Redding at CCR gage compliance point. Note average daily temperature approaches 58°F standard. Salmon egg mortality increases above 56°F.

Tribal Ceremonial Release

Reclamation recently provided a “ceremonial release” of water from Trinity Reservoir for the Hoopa Valley Tribe’s bi-annual Boat Dance Ceremony¹. The release is for the period of August 17-20. The added flow increased the total flow in the upper Trinity River from 450 cfs to a peak of 2670 cfs on August 17 (Figure 1). The flow pulse reached Hoopa at the mouth of the Trinity River on the lower Klamath River one day after the initial release (Figure 2). The flow pulse also had a dramatic effect on the water temperature in the lower Trinity and Klamath Rivers (Figures 3 and 4).

Supplemental Flows

The flow pulse is the first of several anticipated this summer² to cool the lower Klamath and Trinity Rivers, which have been plagued with high water temperatures (70-80F) this summer due to low water supplies related to the fourth year of drought. Low flows and their associated warm water temperatures are thought to be the cause of salmon deaths. These deaths are attributed to: (1) pathogens Ich and Columnaris; and (2) warm water temperatures, low water velocities and volumes, high fish density, and long fish residence times which likely contributed to the disease outbreaks and subsequent mortalities. Adult salmon crowd into limited thermal refuges and become susceptible to disease.

Figure 1. Release of water from Lewiston Dam into the upper Trinity River near Lewiston from August 10-20, 2015.

Figure 2. Streamflow at Hoopa on the lower Trinity River from August 10-20, 2015

Figure 3. Water temperature of lower Trinity River at Hoopa August 10-20, 2015

Figure 4. Water temperature of lower Klamath River at Klamath August 10-20, 2015

By now you have probably heard that Klamath salmon are again threatened by warm water and ICH disease. You may also know that Sacramento River winter run salmon are again threatened with warm water below Shasta at Redding. You may not know that both are related, caused by the US Bureau of Reclamation’s operation of the Central Valley Project (CVP) and in particular Shasta and Trinity reservoirs.

Low flows in the lower Klamath are resulting in warm water and disease, shaping up as having the potential to repeat the massive 2002 die-off of salmon. Water temperatures in the lower Klamath and Trinity near 80°F are killing salmon and blocking their migrations.

Below Shasta on the Sacramento River near Redding, Winter Run Chinook salmon eggs are dying because excessively warm water is being released from Keswick Reservoir near Redding. Water temperatures near or above 60°F occur from Redding down to Red Bluff, the traditional spawning reach of Winter Run Chinook in summer. Egg mortality increases above 56°F.

Here is how the two events are related. The map below shows how the Shasta andTrinity projects are connected as part of the CVP. Trinity Reservoir is presently releasing about 2000 cfs, of which a little less than 500 cfs (52-59°F) is released down the Trinity into the lower Klamath where total flow is 2200 cfs and water temperatures approach 80°F. The other 1500 cfs from Trinity Reservoir is going to Keswick Reservoir via Whiskeytown Reservoir. This 59°F water from Whiskeytown mixes with 5500 cfs of 52°F water released from the Shasta cold-water pool to provide a release of 7000 cfs of 54-56°F water into the Sacramento River from Keswick Dam above Redding. Water temperatures in the Redding spawning reach are 56-60°F.

So the flows diverted from the Trinity are not only contributing to low flows and warm water in lower Klamath, they are also contributing to the water in the Sacramento at Redding that is too warm for salmon eggs. The need to cool Trinity water before it is released into the Sacramento below Keswick is also contributing to the depletion of the limited cold water pool in Shasta reservoir.

Klamath River tribes are asking for more water down the Trinity. Reclamation is offering a small pulse when salmon start to die. A better solution would be to equally split the Trinity release, providing an immediate benefit to the Klamath-Trinity salmon and also saving some of the cold water pool in Shasta. This would require the State Board to reduce deliveries to Sacramento Valley farmers by an additional 500 cfs.