In the coming months and years, regulatory processes involving water rights, water quality, and endangered species will determine the future of Central Valley fishes.

To protect and enhance these fish populations, these processes will need to address four fundamental needs:

1. River Flows
2. River Water Temperatures
3. Delta Outflow, Salinity, and Water Temperature
4. Valley Flood Bypasses

In this post, I summarize a portion of the issues relating to River Flows: Summer Flows. Previous posts covered fall, winter, and spring flows.

Summer flows have long been neglected in water management and water quality standards. This absence is a major factor in the decline of salmon, steelhead, sturgeon, Delta smelt, and other Delta native fishes.

Summer River Flows

River flows in summer drive many natural ecological processes in the Central Valley related to reservoir tailwater spawning, egg incubation, and over-summer rearing in Valley rivers. Valley rim dam releases are prescribed to meet these needs as well as water supply demands. All four salmon runs, steelhead, Pacific lamprey, and white and green sturgeon are dependent on river flows in summer. Below Shasta Reservoir on the Sacramento River, flow is necessary to sustain (1) salmon eggs/embryos, fry, fingerlings, and smolts of winter-run salmon, (2) juvenile fall-run, spring-run, and late-fall-run salmon; (3) juvenile steelhead, and (4) newly hatched fry of green and white sturgeon. Below Oroville and Folsom reservoirs, flow is needed to sustain juvenile steelhead as well as numerous over-summering smolts and pre-spawn adults of both spring-run and fall-run salmon. The Sacramento and San Joaquin Basin Plan (Central Valley Basin Plan) prescribes water quality objectives to protect these beneficial uses. The applicable key water quality objectives are for water temperature and streamflow.

During the dry summer season, much of the Central Valley and Bay-Delta water supply and environmental needs depend on water releases from storage reservoirs. Reaches above the reservoirs and non-dammed streams depend on springs and snowmelt. Like spring-run salmon in un-dammed tributaries, spring-run adults downstream of rim dams, most notably on the Sacramento, Feather, and Yuba rivers, must hold over the summer awaiting their September-October spawning season. Winter-run salmon continue to spawn into August in the Sacramento River below Shasta; their progeny, and the progeny of those that spawned earlier in the summer, are sustained by cold-water dam releases as embryos in gravel beds.

Throughout the summer, winter-run fry move out of their redds downstream of Shasta. Water released from Shasta must be sufficient in amount and cold enough to sustain salmon eggs/embryos, fry, fingerlings, smolts, and over-summering and newly arriving adults, as well as young steelhead. Sufficient river flows are necessary in over 200 miles of the lower Sacramento River to keep water temperatures below lethal levels for salmon, trout, and sturgeon. Adult fall-run salmon, whose migration begins in summer, need cool water (<70°F) to commence their run from the Bay up the river.

The Central Valley water quality plan’s limit of 68°F for the river is rarely enforced. Sacramento River flows of 6000-8000 cfs downstream of the major irrigation diversions are necessary to maintain the required water temperature, but these flows and are met only in wet years (Figure 1). The same holds true for the San Joaquin River, where low flows and high temperatures in late summer hinder that river’s salmon runs. Summer river flows into the Delta are also important in maintaining water temperatures within sustaining levels for Delta smelt (<73°F). Under low Delta inflows, not only is the smelt critical habitat warmer (Figure 2), but it is further upstream in the Delta, away from cooler Bay breezes. Further, during the summer, Delta water temperatures reach critical levels (>73°F) far more often under low Delta outflows (~5000 cfs) than moderate outflows (~10,000 cfs) (Figure 3).

In summary, river flows and water temperatures in summer are critical habitat needs. These needs require stronger summer flow standards and additional management attention to protect the salmon, steelhead, sturgeon, smelt and other species dependent on Central Valley and Bay-Delta habitats during summer portions of their life cycles.

Figure 1. River flow (cfs) in lower Sacramento River below major irrigation diversions in four recent years representing four water-year types. Green line represents minimum flow needed to maintain essential ecological processes in the lower river and Bay-Delta. Red line represents preferred minimum level protecting ecological processes. Summer flow is generally depressed even in wet years.

Figure 2. Water temperature in the north Delta channel of the Sacramento River 2008-2016. Red line denotes 73°F limit of sustainability for Delta smelt.

Figure 3. Delta outflow and water temperature (daily average) at Rio Vista in the north Delta channel of the Sacramento River in summer (mid-June to mid-August) of four recent years: critically dry years 2013 and 2015, below normal year 2016, and wet year 2011. Note that the daily averages are not independent from one another within years, and the effect of air temperature is not shown. Regardless, the effect of flow on water temperature, particularly in the readily controllable flow range of 5,000-15,000 cfs, appears significant among years. Source: CDEC.

I have written often on Delta science and what has been or could be learned from science to support water management.  Yet another biennial Delta science conference, the 9^th, was held this past November.  This year’s conference theme was: “Science for Solutions:  Linking Data and Decisions.”  Another year has passed, and more has been studied and learned.  More dots have joined the dozens of previous dots in data charts from annual surveys of Delta organisms and habitat conditions.  More dots lament the loss of water and habitat.  The huge Delta Science Program has progressed yet another year.

Opening Talk

In Phil Isenberg’s opening talk, “A Guide for the Perplexed”, the former legislator and former chair of the Delta Stewardship Council suggested that scientists learn to smile more.  He asked: “Why should science be involved in policy anyway?”  He talked about how policy makers view science.  (Obviously, many are perplexed.)  He forgot that the universe and Mother Nature are vastly mysterious things, which are often more complicated than human understanding, but sensitive to human actions at the same time.  Yes, science is perplexing.

Mr. Isenberg talked about “independent science” and “combat science,” as though they were two different things.  To borrow a legal term, science is not self-executing.  Then he asked: “How do we know when we are using the best-available science”?  His answer: “When it is good enough to avoid doing something stupid.”  Clearly, we have yet to reach that point.  The problem has been in choosing to do the best thing, not that good choices or unknown or not “available.”  He then quoted Churchill:  “America will always do the right thing after trying everything else first”.  At least we have gotten past the point where we thought the world is flat.  It is all very perplexing.

Mr. Isenberg concluded by suggesting: “It’s the notion that scientists live looking farther out than the rest of us do with the gift of foresight that if properly utilized, can inform, educate, and ultimately motivate policy makers.”   He forgets that ultimately policy makers must trust scientists to get the job done.  Example: the Trinity Project and the atomic bomb in the 1940’s.  As long as water managers and policy makers lead the science, the Delta’s problems will not be solved.

The Delta Science Program

Clifford Dahm, former lead scientist for the Delta Stewardship Council, spoke on his Delta Science Program, which was forced upon us in the 2009 Delta Reform Act to ensure water and environmental policy are guided by the “highest caliber” science.  He spoke on the program’s Independent Science Board, outsiders who meet once a year to review “our science”.  He spoke on their Adaptive Management Program, which ensures that we evaluate everything and learn nothing.  He spoke on the program’s efforts to coordinate science and inform decision makers, and to develop and implement the Delta Science Plan and promote the Science Action Agenda.  He talked about their modeling efforts: “There’s just a lot of ways that modeling could be moved forward, and I hope that in the next two years, we can actually come back to you and say that some of our modeling efforts have shown greater fruition as time goes on.  We were talking about the idea of potentially a modeling center or a co-laboratory to get modelers together.”  Those would be the two years after which we will have new water quality standards, new biological opinions, and new tunnel-boring machines in the Delta, as well as several newly extinct native fish species.  They would also be the two years after 20 years of effort starting with the CalFed Bay-Delta Program.

A Great Question

U.C. Davis fisheries biologist Peter Moyle then addressed the question:  “How has your research program and the data it has produced over the last 35 years been used to develop solutions for conserving aquatic resources in Delta?”  He quoted the 1998 Strategic Plan:

This strategic plan, if followed, should lead to an orderly and successful program of adaptive ecosystem restoration….  The Strategic Plan Core Team has high expectations for the Ecosystem Restoration Program.  There is no turning back and the team anticipates that in 20-30 years many habitats will be restored, endangered species will become abundant enough to be delisted, and conflicts will be lessened , even in the face of population growth and increasing demands on resources.

In addressing the posed question, he then remarked:

In retrospect, now that almost 20 years has past since that was written, the statement almost seems tongue in cheek because clearly that has not happened.  I continue to help write reports that recommend how to improve the Delta ecosystem and frankly I don’t see much progress being made, as the delta smelt trends so eloquently attests…  the reality is that the Delta has continued to deteriorate as a habitat for native fishes, despite my research and despite many proposals for solutions.

His experience, like that of so many other long-time Delta scientists, is that few if any of the specific recommendations in the Strategic Plan have been implemented or completed.  Science has done its job, and scientists have long awaited action.  Policy makers and managers have failed us, not the science.

The use of science in complex public policy decision making

Chair of the State Water Board Felicia Marcus spoke on the use of science in decision making.  She suggested to scientists:  “Dare to recommend, but don’t decree …  Retain your scientific integrity but dare to make recommendations.  At the same time, own your power and be responsible with it and have empathy for the decision makers who have to balance, even as you would have them respect you.”  This is a very tough sell for scientists who have not been listened to for decades.  What will she and her Board do with two more rounds of recommendations on the Delta tunnels and the Bay-Delta Plan?  Will her Board be as transparent and methodical in their balancing as the scientists are in making their recommendations?

Chair Marcus further stated:

We’re entering the era of adaptive management that requires all of the above as well as integrating social sciences into our work … To make adaptive management work, we all have to learn how to be better ‘egosystem’ managers in order to be better ecosystem managers in the real world over time, versus lurching from sound bite to sound bite or wringing our hands that other players just don’t get it.

Sorry, but that’s not the problem.  It gives the policy makers and the managers too much credit and scientists too little.  Very few scientists think that managerial ignorance or lack of cognition is the biggest problem.  Rather, it’s that scientists have endured decades of adaptive management in which their lessons and caveats have on the whole been subsumed to the social sciences of politics and economics.  There are plenty of scientists throughout the resource agencies and non-profit groups who are extremely articulate and who have great senses of humor and social skills.   That hasn’t changed the outcomes: fish and other parts of the Bay-Delta aquatic ecosystem are in crisis, and the agricultural economy and other values against which the ecosystem is “balanced” are thriving..  And that balance sheet is really nothing to smile about.