Independent science panels present findings to the Delta Stewardship Council from Delta flows workshops

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At the July 25 meeting of the Delta Stewardship Council, the council members heard an informational update on two independent science panel reviews on Delta flows and related stressors intended to help inform the State Water Resources Control Board’s update to the Bay-Delta Water Quality Control Plan (Bay-Delta Plan) that is currently underway.

The update to the Bay-Delta Plan is focusing on evaluating the impact of insufficient freshwater flows as one of the stressors that may be contributing to the plummeting fish populations in the estuary.  At the request of the State Water Board, the Delta Science Program conducted two workshops in the spring of 2014, one on Delta outflows and the other on Delta interior flows, to help the Board with its review of the Bay-Delta Water Quality Control Plan.

For the workshops, we took the flow objectives and we split them into two parts,” explained Sam Harader, Program Manager with the Delta Science Program. “The outflows workshop is related to how much water flows out of the Delta to Suisun Bay and to the rest of the estuary, and that’s primarily related to fish habitat and the productivity of the estuarine part of the system. The interior Delta flows workshop dealt with flows within and across the Delta. It’s related a lot to entrainment but also how fish move through the Delta and how that affects their migration.”

The purpose of the workshops was to identify the best available science to inform the Board’s decisions. For each workshop, an independent panel of science experts was assembled and given the necessary publications, reports and presentations to assess the state of scientific knowledge.

The panel presentations began with Les Grober, Assistant Deputy Director for the Division of Water Rights at the State Water Resources Control Board who discussed where the Board is at in the update process as well as how they are going to use this information. He will be followed by Dr. Denise Reed, chair of the Delta Outflows and Related Stressors workshop panel, and Dr. Kenny Rose, spokesperson for the Delta Interior Flows and Related Stressors workshop panel who both discussed some of their panel’s specific findings.

Les Grober, Assistant Deputy Director, Division of Water Rights, State Water Resources Control Board

Les Grober began by thanking the Council for their science support, because sound science and the scientific basis for what we do is really foundational.  All of the regional water boards do water quality control plans that identify the beneficial uses that need to be protected, the water quality objectives to protect those uses, and a program of implementation to achieve the objectives, he said. “The water quality and water rights really come together with the Bay Delta Plan because it’s the choke point for a lot of the water in the state, so it has both a water quality nexus and a big flow and water right nexus.”

Ultimately when we do these water quality control plans, we have to do the balancing of not just the science but also the policy implications of water quality objectives, so this is really the expansive role when we’re developing the science upon which everything else will be founded,” he said.

Les Grober 1The plans are periodically updated; the last big update was in 1995 and the an update in 2006, he said. “They are not self-implementing,” he said. “These water quality control plans are then implemented at least in part through water rights actions – a water right decision.”

He then presented a slide detailing some of the history, saying that the process of determining the right mix of flows for other beneficial uses and the environment has been going on for quite some time. “We’ve developed interim objectives and plans to implement those interim objectives, some of them successful, some of them not,” he said. “For example, we have a 1991 plan for salinity that was never implemented. There was a draft decision that was never adopted, at least in part because it was overreaching and perhaps it didn’t’ strike the right balance in terms of the science and the policy implications. We had the 1995 plan and Decision 1641 that implemented that plan, and that’s really been the foundation for operations of the state and federal projects and other things in the Delta since that time, in conjunction with biological opinions and their RPAs.”

In 2009, the Delta Reform Act charged the State Water Board with determining what flows were needed for ecosystem protection, not looking at the policy implications, and not doing the balancing, he said. “It’s perhaps an understatement to say that it brought attention to the issue because there were some relatively high numbers that were proposed,” he said. “That was one of the foundational documents that the panels reviewed, to look at those numbers, because that culminated in the 2010 Delta Flow Criteria Report, but I’ll emphasize once again, that didn’t do the balancing, that was just what does the science suggest.”

The report had a number of conclusions, he said. “It looked at some high flow amounts – it was saying 75% of unimpaired flow in the Sacramento River and in the Delta and 60% for the San Joaquin River,” he said. “These are all high-end flows that the board has said many times that it’s unlikely it would adopt such flows because of the high economic costs, the high hydropower costs, but it provides in that way perhaps a bookend in terms of what’s the high end. Of course, there’s some biological basis for those numbers.” He noted that the report also discussed the importance for connectivity of flows.

The State Water Board is updating the Bay-Delta Water Quality Control Plan in four phases, he said. Phase one is looking at flow objectives for the San Joaquin River to protect fish, predominantly salmon, as well as south Delta salinity objectives; Phase two looks at everything else in the water quality control plan; phase 3 is the implementation of phases one and two; and phase four will look at objectives for high priority tributaries to the Delta.

He then gave more detail on phase two. “Phase two is looking at everything other than San Joaquin River so it includes how do you protect San Joaquin River flows if you get it to the input to the Delta, and that’s why we’re looking at in-Delta flows, reverse flows in Old and Middle River, and how much of the San Joaquin River actually needs to make it out into the Delta and the Bay,” he said. “Phase two also looks at Sacramento River inflows, export – imports, the hydrodynamics of the Delta, including the Delta Cross Channel Gate closure, Suisun Marsh salinity, and other water quality issues. We’re also looking at flood plain habitat, because that’s something that has emerged as an issue. It’s not just about flows but it’s about habitat in particular in regard to floodplains.”

The plans always include monitoring and special studies which provides good information, because we’ll have to determine certain things now and leave other information that we need to develop through adaptive management as the process continues, he said.

The State Water Board has held a number of workshops, and in 2012, a report was prepared by a consultant as to what we know and what we don’t know, he said. “That is really what stemmed the charge to these panels,” said Mr. Grober. “Foundational to our phase 2 effort, what do we know and what don’t we know about X2, the low salinity zone, and hydrodynamics in the Delta, and are those the right things to be looking at.”

Mr. Grober then turned to what the State Water Board is hoping to get from the workshops. “As we expected, there’s a lot of work to be done and it’s helpful that we know it’s not a simple problem,” he said. “It’s been referred to as the ‘wicked’ problem … you could study the Delta forever and not necessarily get a better answer, so what we’re going to have to take from these reports is what do we know now, … we didn’t’ hear that you’re completely on the wrong track, these are some of the things to look at, and by the way, you can improve what you’re doing by looking at these things.”

The ultimate goal is to determine what we do know, as perhaps we know more than we think, he said. One of the next steps will be to release a scientific basis report that will be a synthesis of everything the Board has in front of them, including the reports from these panels which will be released later this year. “It doesn’t do the policy stuff yet, it doesn’t do the balancing, it’s not the economics, but it’s a synthesis of everything that we have in front of us, including the reports from these panels that we will be releasing sometime later this year,” he said, adding that they had hoped to do it sooner but drought activities have kept people busy. The report should be available towards the end of the year with a workshop most likely early next year, he said.

Mr. Grober also noted that the Board might take advantage of opportunities to work with the Delta Science Program and the Science Board again to review other critical elements.

Grober TimelineHe then presented a slide with a timeline, noting the release of the report and workshop on the scientific basis in the beginning of 2015. “There would be a hearing on the adequacy of the environmental documents that are being concurrently prepared by about this time next year, and for the Board consideration into late 2015, early 2016,” he said, noting that it might be optimistic because of drought activities.

There are benefits to the drought because we understand that it’s another thing that we need to be evaluating as part of our long term planning to be prepared for a year like this or perhaps worse, and so with that … “

Dr. Denise Reed, Outflows and Related Stressors Panel

Sam Harader then introduced Dr. Denise Reed, who was chair of the outflows panel, noting that she is chief scientist for the Water Institute of the Gulf and a nationally and internationally recognized expert on coastal marsh sustainability and how human activity can affect those marshes.

Dr. Reed began by saying that she is representing a very impressive group that came from many different backgrounds, with experience from fisheries, general ecology, water quality, and physical processes as well as statistical analysis. The panel was formed and began work on 2013, holding a two-day workshop in February of 2014. A number of different perspectives and impressive array of information were presented in the workshop, and the panel was able to have extensive discussion with participants during the workshop to really identify the heart of the matter, she said.

The panel was charged with answering a series of five questions.

Dr. Reed 2The first question was what are the key studies and synthesis reports that the State Water Board should rely on in making their decisions on Delta outflow requirements. “We don’t’ have a list,” said Dr. Reed. “This was felt not to be something that was a very useful way of the panel presenting their opinion; rather, in relation to the questions that the bulk of the report addresses, the commentary about specific studies and some key benchmark ones that support particular points that the panel wanted to make are highlighted, so you will see in the report no specific response to question 1.

The panel did spend a lot of time thinking about X2, and at the beginning of the report is a background and history about the concept of X2, how it arose back in 1993 and how it was thought of and measured back then as approaches to measurement have evolved over the years, she said.

The panel had some issues with the equations, Dr. Reed said. “There are some pretty important assumptions about X2 and about the layering of fresh water and salt water and how those assumptions were made back in the early 1990s when this specific criteria or indicator was selected,” she said. “These may not hold up under all kinds of circumstances and it may mean that when the position of the two-line, when it is either far seaward or far landward, that we may not be actually representing the conditions that we think we are, and so there is some quite extensive discussion in the report about that.”

Another important point is that X2 is frequently used as the independent variable in regression analyses where the dependent variable is some index measure of some population abundance, she said. “We feel that anybody who is interpreting those types of analyses or diagrams should really think about what those represent, and that they represent multi-year collections of seasonal sampling across multiple stations and they are really an aggregation of data that is very complex. I won’t call it big; it’s complex.”

It’s a very gross measure of the indication of the position of the estuarine salinity gradient, Dr. Reed pointed out. “We have this gross measure of how the estuary’s working and we have one number that represents a complex distribution of animals and so … we feel that X2 still has some value, but we don’t think that these fine scale use of this tool is really appropriate, certainly when you think about the data that goes into those regressions.”

X2 Picture SWRCBEssentially it’s really about fine scale management of X2, she said. “The idea that our measurement techniques in 2014 really allow us to tune this down very well; we can measure it very well, but should we use that as a management tool – that was a question we spent a lot of time considering. … So in the report we talk about how one might think about that.” She said that if one can identify a reasonable biological rationale fine-scale management of X2 that can be clearly expressed and agreed upon, then it can be implemented in an adaptive management experiment where field data is collected to test the rationale. Until this has been accomplished, it is important to remember that existing X2-abundance relationships do not provide the rationale for fine-scale management of X2, she said. “In the current form, the relationships don’t support that.”

This gets to the second question, which is should we still be using the X2 relationships, or are there other indicators that might be more reasonable, she said. “The panel would like to really communicate very clearly that a single indicator for a system as complex as this is really an unrealistic thing to expect, and that a suite of indicators that could include X2 is probably a more reasonable approach here,” she said. “The idea here is that there are specific species that are represented in some of these relationships that X2 is managed towards, but there are other aspects of the ecosystem that we know that we’re all interested in, so a suite of indicators is more appropriate that could include X2.”

The panel felt that the frequently used diagrams representing abundance versus X2 really need a more rigorous representation of uncertainty, she said. The diagrams tend to be logarithmic scales so a very small change in X2 could mean a large difference in the index, but given that it’s a log scale, it could be a large or small change, depending on how that log scale plays out, she said. “There was a lot of early agreement on this that the log scales are good, but also representing for the public and for others the linear representation of that data too, so people can more readily get their minds around what an incremental change is likely to mean in that index in the kinds of quantities that we use in daily life, linear measurements.”

The panel listed additional factors that could be factors in the development of indicators, such as changes in X2 between seasons and water-year types; habitat suitability, spatial and temporal dynamics of the area and volume of the habitat; water age; benthos community structure and function; patterns of gross energy flows in the system; and flowpath-related metrics such as the split between Sacramento and San Joaquin flows. “This is just a subset of some of the kinds of things that might be included in those that could be important in terms of the larger ecosystem, again the idea is that abundance indices are one thing, but we probably really want to know if these animals are growing, whether they are reproducing, whether they are dying, these kinds of vital rates, the things that actually measure what’s happening in the population …

The third question is about how much do you need to move this to make a difference, are there thresholds in this, and how can we use adaptive management,” she said, noting that she is paraphrasing as these are quite complex and wordy questions. “We make an observation quite clear about the potential for improvement in Delta smelt by movement of X2.” There is little evidence that the relatively modest changes in fall Delta outflows being proposed are going to result in substantive increases in abundance of key pelagic fish species based on their X2-abundance relationships. “We really are moving around within a very narrow range and these really are relatively modest changes, so there may not be substantial increases in some of the key pelagic species that the expectation is provided for.

Substantive increases in the longfin smelt abundance index may be realized under the proposed 75% winter-spring unimpaired flow standard, but even in that case, population changes may be difficult to detect, given the observation error in the sampling programs, and the infrequent implementation of high flows, even under the unimpaired flow strategy. “These general relationships are built on a very variable database, so that doesn’t necessarily mean that in any one year that the particular response will be realized because of the generalization of the data that goes into the index and the variability within the system. I think that’s quite an important caution for the use of a simple index like this.”

There’s a lot of data here, which is good, but it does have its limitations, she said. Models are useful, but their complexity can surpass the information available. “The community here has made enormous progress on modeling, but sometimes the complexity of those models and how we theoretically understand those processes, particularly for the biology, go a little bit beyond the ability of the data to support them,” said Dr. Reed.

The panel encourages continued but thoughtful use of multistage life-cycle modeling in the analysis of Bay-Delta data, but it’s critical that quantitative analyses communicate uncertainty in recommended flow criteria to decision makers.

In regards to adaptive management, there is this Catch-22 in the sense of really whether or not the science is there for decision makers to feel comfortable in the outcomes of a very large action or the use of a lot of water in terms of moving X2, she said. “It’s difficult to improve those model predictions and give people more confidence without actually doing it, and so we’re in this difficult situation. There is text in our report that talks about how it’s quite difficult to do effective adaptive management in a system as large as this where one only has limited opportunities on an annual cycle for making changes, and that those changes have large implications, economically and potentially have risks associated with them. There are other approaches to dealing with these kinds of uncertainties such as thinking about scenarios rather than particular adaptive management approaches that might be more appropriate in a system like this. Perhaps utilize some of the principles of adaptive management, but perhaps not some of the more theoretical discourse on that. It might not be appropriate to carry that forward in a system like this.”

The fourth question asked how other factors that affect fish, habitat, and other ecosystem attributes likely to interact with Delta outflow requirements. “It seems like it’s something that we struggle with here – how can we understand the effects of these multiple stressors on the fish if we just address flow and not the other stressors, if we just address the other stressors and not the flow, and how is this likely to play out,” Dr. Reed said. “It’s really not so much the flow that’s the proximal influence when we manipulate something like X2; it’s really an indicator of a number of other things that actually occur within the system, and so we really have to understand that when we move X2, when we change outflow, we’re changing a number of other processes too that also influence the role of some of those other stressors.”

One of the most important points that the panel wanted to convey here is the idea of change in this system, she said. Ecosystem change in the Delta has been continuous for decades, and this slow continual change has been punctuated by events such as the sudden increase in invasive clams and the decline in chlorophyll and pelagic organisms that followed. While such events are dramatic, it should be kept in mind that continuous change has been taking place at all trophic levels before such events occurred, she said.

There is a lot in the report on ammonium, said Dr. Reed. “The panel really thought about whether or not the discourse here about the role of ammonium actually really reflected whether there were alternative explanations or not,” she said. “The idea is that we know quite well as a scientific community that ammonium concentrations greater than some threshold inhibit the uptake of nitrate by phytoplankton. Ammonium, nitrate, and phytoplankton – it’s how they work together, so if you have high ammonium concentrations above this threshold, then you’ve not going to have a lot of phytoplankton because they’re not going to be able to grow very fast. Once the phytoplankton transition to nitrate, then they grow a lot, so then the nitrate is drawn down and you have a lot of phytoplankton. However, there are other things going on in this system. There are other things other than ammonium and nitrate that could be influencing phytoplankton growth and so we hypothesize and lay out a potential set of cause and effects in the report … essentially what we’re saying is that certainly these conditions don’t necessarily support some of the ways they’re often interpreted. There are other questions here that need to be answered.”

Perhaps there is a theme here which is – my words, not the panel’s – beware of latching on too quickly to one specific attractive idea and be sure to question and think about alternative explanations and think broadly about these things. These are difficult issues and the additional interpretations need to be taken seriously and considered,” said Dr. Reed.

We think there’s a lot of potential for the development of a Delta ecosystem model as the hydrodynamics modeling has clearly moved to a really good place at the moment,” she said. “There are some promising developments where some ecology could be added onto these kinds of things that would really make it more important.

The fifth question was how should Delta outflow be measured and managed to better reflect the flows necessary to protect estuarine fish, estuarine fish habitat, and other important ecosystem attributes. “This is really about the management of X2 in the winter and spring, the management of X2 in summer and fall, and the effects of those particular management strategies on that seasonal basis,” she said. “The high outflows in the winter and spring clearly seem to benefit a variety of species. I think we felt quite confident about that. When we get to summer and fall, it gets a little bit more difficult, and this is where the fall outflow adaptive management approach may be an appropriate way to move forward with the caveats we had earlier about adaptive management with the limited opportunity to manage the system in a way to learn from it. But really the bottom line here is that managing flows, it seems to the panel, can provide at least coarse level of protection to estuarine fish and ecosystem health. However, just using the flow objectives on a monthly or seasonal basis is not going to give you everything you need to ensure that protection.”

As a panel, we spent a lot of time going back to 1993 reports and trying to understand how this concept had been developed,” she said. “It struck us that we’ve been at this for two decades, and perhaps have not had the effect that may have been desired. … The system has changed over those 20 years, and so perhaps then the management of the system also needs to change.”

It shouldn’t be a surprise to you that an external panel like this would feel the need to say this very strongly to beware of what correlations really represent, and be aware of what data goes into those relationships that you see on those simple graphs,” she said. “Think about cause and effect, think about the mechanisms, but don’t forget that information, and the idea of change over time and how management practices and our policies can adjust and be responsive to that change and anticipate change in the future.”

And lastly, a comment from me,” she said. “This is very difficult, and I don’t think anybody on our panel comes into this or makes any other remarks suggesting that there are easy solutions here, but we hope that what we have laid out is going to be helpful in moving forward.”

Phil 1One of the things you did is remind us what the real and unreal expectations were back in the 1990s when X2 was developed, and I thought that was frankly refreshing,” said Council member Phil Isenberg. He notes that in the report, the panel suggests using other indicators in addition to X2 for management of the system. What are the five or six things that the panel thinks is most important to add to X2, he asks.

In the report, there are a number of things listed and we didn’t spend time trying to prioritize those,” Dr. Reed responded. “I would suggest one has to have slightly more specific management objectives in order to identify what those things should be. … The challenge that we have is that we have a number of management objectives, and in the questions posed to the panel, there is a phrase that talks about important species and other important ecological attributes. That’s a general term of art, if you like, it’s all the things we care about relative to this system, and I would suggest that a suite of indicators needs to make sure that they represent in some way, all of those different things that you as a society and policy makers care about that system, and then they have to be balanced in some way. Understanding the details of the management objectives and which particular elements of the system you need to have represented so they’re in front of you when you make the decisions, that’s the thing that drives what the indicators are.”

Clearly X2 has led to an increase in invasive species population on the fresh water side and the saltwater side,” asks Chair Randy Fiorini. “Did the panel consider fluctuating X2 as a method of managing invasive species and thus improving the food web as something that the water board should consider?

Dr. Reed niceWe talked about that, but perhaps not that directly,” replied Dr. Reed. “I’m not sure that I would agree that X2 had led to invasive species, but it may have provided conditions where invasive species have been able to thrive. … I think the issue there comes back to one of the points made in the presentation that’s in the report. It is in the extremes where some change might be affected, but whether or not we’re prepared to take the risk of doing that is something that needs to be clearly thought through. This is the idea of the uncertainty about the relationship becomes greater when it’s either way seaward or way landward, that we talk about in the report. It’s the idea of being in this Catch-22, there are no guarantees, and it’s not a word that should even be in the conversation, because certainly from the ecosystem side, there won’t be any guarantees. And so there’s a risk there in doing that. Everybody has to buy into that risk.”

Those conditions exist today. Salinity has intruded into the Delta further than it has in a long, long time,” said Chair Fiorini. “Are we missing an opportunity to study this effect and the potential impact on the food web?

I would say there may be an opportunity there not only to study, but to understand and inform our management practice,” she said. “The issue of reliability for me is not about it being the same all the time, but it’s about knowing when there’s more and knowing when there’s going to be less and with a reasonable level of assurance, so the idea that the policy framework may allow a lot more water use in some times than in others seems to be something that has some potential within this system. Now what you lose and what you gain from that has to be considered in a much larger picture.”

“I think the panel is very much aware that there are real issues on the non-ecosystem side here that have to be taken into account, and so whether or not those can be appropriately ‘traded-off’ within this room or within the state legislature is something that is not a technical decision; that is not a scientific decision,” she continued.  “What the scientist can do should be to help you understand what could happen if that occurs, something about our confidence in it now, and that will be the information that will go into the decision. … It doesn’t tell you whether or not you should do it, but why do you do it? Because there are other things you want to achieve and so I know it isn’t very useful to say that it’s difficult, you know it’s difficult, but there’s an expectation that science can provide you with a tool that you can use, science could probably come up with some indicators for you, multiple indicators, but then how you then use those in making the decision, is really about societal preferences and priorities, not so much about how the ecosystem works.”

Dr. Kenneth Rose, Interior Delta Flows and Related Stressors Panel

Dr. Kenneth Rose is a professor of Oceanography and Coastal Sciences at Louisiana State University with a strong research record on fisheries.  He talked about the interior flows and stressors workshop, noting that his panel’s report has not been released yet. Our report is organized differently than the first, he said. There is an executive summary which summarizes the responses to the charge questions, but the main text is organized by topic, because his panel felt they were more comfortable by topic and cross-referencing rather than just answering the questions alone, he noted.

Dr. Rose 2The first charge question was almost the same as the other panels except substituting interior Delta flow for outflows, he said. “Surprisingly, this seems like a straightforward question, but for scientists, it’s actually difficult because we’re always faced with the question of what papers do we trust more than others, and what are more convincing than others. So in this case … you could judge what we thought was important by the ones we cited, at least in positive ways in our report, which is probably the best way to judge what we thought were good papers because that influenced our text.”

There’s a lot of very good science; however, the panel was concerned that little experimentally validated quantitative guidance on flow management was available to the Board,” he said. “It’s in the structure of how science is done here with a lot of independent studies trying to form a scientific program and that’s a real challenge, and we discussed that in detail in our report. There are too many correlations and not enough understanding in many of these studies, although the science has progressed quite a bit over the past 10 years.”

The second question notes that the interior flows have been altered in many ways, their timing and magnitude, and asks what are the relationships between these interior flows and native fish, he said. “The answer is that within the Delta, there are a lot of factors going on that affects them, and these include velocities of the water, sediment, nutrients – it’s hard for us, we have shifting baselines, we only remember our generation or one generation back, but in this case, for the fish, they live in evolutionary time, so you really have to think what they became adapted to before pre-1900, even earlier than that. So the Delta is very different from then, and that has affected their vital rates.”

There’s been a huge decoupling of flow from how flow used to interact with available habitat and that’s been said many times before that it’s not just flow,” he said. “Seasonality is very important, as well as the low salinity zone which of course is not within the Delta most of the time, but is greatly influenced by what goes on in the interior of the Delta.”

The panel doesn’t think it’s a good idea to keep talking about flow because fish don’t really care about flow, he said. “Fish care about the components of flow: velocity, depth, those things. We thought it would be very helpful if we stopped making vague statements that ask how does flow affect fish. For a scientist, that’s not a very meaningful statement. What do you mean by flow, and what do you mean by effects?

Understanding fish movement and migratory patterns is improving within the Delta, but it still needs to be improved more because of the fine time scales and space scales, he said, noting that the technology is rapidly improving and is being used more and more.

The third question was how non-flow stressors affect all the things in question 2, he said. “This was a little tricky within the Delta,” he said. “There’s a lot of particular organic matter is exported out of the Delta, which means what happens inside the Delta affects down the estuary, and there are a lot of things going on down-estuary.”

Successful invasions of invasive species have been prevalent during drought periods, so there needs to be an extra sense of caution during drought periods where X2 is located, as there tends to be correlations, although we don’t like correlations,” he said.  “But we do know that there are some pretty good mechanistic understandings of why those correlations with drought have occurred.”

Predation is important as a non-flow stressor, but we just don’t know what proportion of total mortality is due to predation because so many other things have changed that affect the mortality rate, so it’s hard to know what proportion is predation, but despite being difficult to isolate, it’s likely still significant. Of course, entrainment continues to be important but probably not as well-qualified as it should be.”

The fourth question asked about what metrics of interior Delta flows such as Old and Middle River (OMR), key west flows, and export/import are useful, he said. “We’ve become very cautious about many of these metrics that are tidally-averaged, because of the great influence of tides on the velocities that you see in the system. Things that average that out always make us a little nervous.”

On the other hand, there’s pretty good evidence that entrainment of Delta smelt seems to be related to OMR,” he said. “It’s hard to define a particular threshold as there are a lot of uncertainties that deserve respect, but the panel said they were surprised, given all the uncertainties and measurement problems, there still was a relationship there. It’s similar to the X2 argument; it’s withstood the test of time although at times and it may be overused because of not paying attention to the uncertainty and where you’re at with that, but there’s something there.”

The fifth question asked what changes to the interior Delta flows or other stressors would be effective for improving conditions for native fish and the ecosystem. “Several key points … You must consider the hydrograph over the entire year. This is not a spring flow; it’s not a summer flow problem; it’s an all year round flow problem, and there’s always some critter somewhere who it using this environment and habitat, so there’s a tendency for us to focus in too far on particular seasons or perhaps particular locations when we really need to consider the hydrograph over the entire year.”

We were not able to figure out from the literature, again this is a synthesis, that if you route things differently within the interior Delta, what comes out and influences the low salinity zone, which is a key habitat area,” he said. “We were not able to find a lot of good information on that. We were a bit surprised by that. That might be a good area for some study.”

We don’t like this ranking of stressors – which one is more important than the other,” he said. “They are too interrelated and they’re not that separable. … We do think that OMR and Delta smelt entrainment can be used with proper caution as a management tool.”

The report has much to say about adaptive management. “It’s a great idea and concept,” said Dr. Rose. “Our opinion was that we have yet to see it be done effectively in this system. There are some examples where parts were done well, but I don’t think we’ve seen the full package done as effectively as it could be. … There are certain problems where adaptive management is well suited for, but it’s not a tool that fits every problem.”

Council July Science PanelFinally, he said he’d go through some of the things that didn’t show up in those answers to questions but were still in the text of the report. “It’s a wicked problem, you’ve heard that before, and the tides are very important. You can link interior flows to some of the local responses of the fish; going to the population level is more of a challenge. It’s doable but you end up dealing with models that people can argue over, particular population models.”

What is the best scientific information?” he said. “We’re not going to tell you what the best papers are, but we did tell you how you go about judging those papers. We go through a lot about the scientific method and statistics and we were critical of some of the papers that are out there; they fall short on following what many would consider best practices in analysis, and others were very well done. We think it’s time to take all these studies and put them into a formal approach to try to estimate overall effects of flow … “

We think that use of unimpaired flows is informative, but not definitive,” he said. “Timing and volume of water is important, but it’s not just the water. It’s what’s in the water, it’s what the water’s doing, it’s how fast the water is moving, and it’s how water gives you access to other places to go.

Please move away from only considering flows and ratios and think about what the components of those flows and ratios are doing,” he said. “Velocities, transport, how does it relate to the behavior. It’s not clear how interior Delta actions effect production down estuary, and the interior Delta is still too much of a black box for fish in terms of survival following their routing paths and how they would progress. We’re thinking salmon as well as Delta smelt as well as other species. We have to keep reminding ourselves, this is not a two-species system, our training is in fisheries so we end up doing that, but the panel was very clear; this is a multi-species food web problem.”

Say what you mean by flow, abundances, and indices as we’re very loose with those terms, he said. “They have precise and accurate definitions and we should use them. And what we mean by effects: if it doesn’t affect growth, mortality, reproduction, or movement of individuals, then I don’t know what you mean by effects, if we’re thinking fish. I think precision in communication is going to help somewhat clarify the differences.”

Adaptive management can be done effectively, and the MAST study is encouraging, he said. “There’s also a tendency to take difficult decisions and delay doing them by putting them into adaptive management context, and that’s not an effective use of adaptive management.

The estimation of salvage and entrainment needs to be improved, he said. “The data has been massaged on salvage; we don’t’ think you can go back and improve those data historically, but by renanalyzing them, however, you can do studies now that will help you refine your historical estimates, and we think that’s a better direction to go in.”

With modeling, expectations are the biggest problem, he said. “People have high expectations of these types of ecological models, they are very useful but they need to be used properly.”

Finally, with respect to programmatic science, there’s a large section in the report about this idea of trying to overlay multiple individual studies to address a large complex problem, he said. “You end up with what’s called leakage. Critical information gets lost as you keep simplifying it and simplifying it until you get down to something that is actually not that useful and often that’s the level of information that gets crossed over into management and regulation, and this is more complex than that. We offer some suggestions for minimizing leakage when things are organized that way.”

Then finally, we hope this helps … “

Council member Phil Isenberg asks Dr. Rose about his statement about unimpaired flows.

What we said was it was informative but not definitive,” replied Dr. Rose.

And it is informative, because …?” asked Mr. Isenberg.

It’s informative because if its calculated appropriately, it does tell you what flows would look like in the current configuration of the system without all the extractions, so that’s informative,” said Dr. Rose. “Our group felt that taking a fixed percent of that was not the complete picture. To be frank, that was our bottom line because we think there are several pools of information, that being one of them, to draw from, and then of course there are practical constraints. I think I would approach it that way.

Council member Judge Damrell asks him to expand on his cautionary words regarding adaptive management.

One caution is that this system is constrained in how much it can be manipulated,” replied Dr. Rose. “We have several key biological opinions, several listed species, and operating constraints. I think the Vernalis adaptive management program was a great idea but they also, after 8 years, they really couldn’t see the full range of conditions that would have been ideal for really deciding the response to a change. A lot of useful information was obtained from that, but one of the challenges in this system is the constraints to manipulate it. True active adaptive management lets you really manipulate the system to let you see responses, and here it’s constrained, so that’s one caution.”

A second caution would be that the monitoring is often not sufficient to detect the kinds of changes that these relatively small perturbations are doing, so there’s a measurement on the response side of it,” he continued. “It can be done but it’s expensive. It’s a complicated system. It’d be easier in a bathtub to work.”

A third limitation is there’s a level of distrust in the scientific and stakeholder community that makes a cooperative study which adaptive management needs challenging. And that’s a people problem that people go along with it until they decide … well, there’s a great degree of distrust that needs to be dealt with in order for adaptive management to be really effective,” he said.

On the positive side, in a system that’s this complex and that is really well measured, the monitoring is very good here,” he said. “In general, I think it’s one of the most monitored estuaries I’ve had the pleasure of being involved with … so there is an opportunity to use adaptive management to address some of these questions because a lot of the baseline measurements are available … there’s a lot of historical information here, which helps you in adaptive management, and I think some of the problems are well suited for it because they are manipulable … “

  • Note: The panel report for the Delta interior flows workshop was in the finishing stages and has not been released yet.
  • For Dr. Kenneth Rose’s power point, click here.

For more information …

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