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Council looks to Science for Approach to Delta Plan

December 2010

Science was center stage at the Delta Stewardship Council’s December meeting, as three lead scientists presented reports that will factor into the development of the forthcoming Delta Plan. As the plan takes shape, science – the latest and best available – will be crucial to provide context and direction.

“We spend all this time talking about process, every once in a while we should talk about some science,” Council Chair Phil Isenberg said during the meeting.

The Council heard from lead DSC scientist Dr. Cliff Dahm, lead Interagency Ecology Program scientist Dr. Anke Mueller-Solger and Independent Science Board Chair Dr. Richard Norgaard.

Lead Scientist's Report

Dahm discussed three climate indices (weather patterns used to predict future hydrology) and explained the importance of each to the health of the Delta. The indices discussed were the El Niño (La Niña) Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) and the North Pacific Gyre Oscillation (NPGO).

Dahm mentioned that climate indices provide useful insights into precipitation patterns in the western U.S. and the dynamics of fish populations in San Francisco Bay and the California Delta.

“The reason I bring this up is that when we start to try to understand whether or not various kinds of restoration activities are having a positive effect in the Delta, we need to realize that some of the interannual variability is linked to some of these kind of climate indices and some of the conditions that exist out in the open ocean,” Dahm said.

Dahm went on to explain that climate indices can assist ecosystem and water supply planning and management by providing some foresight into conditions up to a year in the future.

“Unless you factor that in to your analysis, you’re not going to get the best understanding of what activities centered around the Delta are having what effect,” Dahm said. “I think one of the things that [the study of climate indices] argues for is that you need long-term trends analysis. You can’t base your decisions on one good year or one bad year.”

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The Interagency Ecological Program (IEP)

IEP lead scientist Dr. Anke Mueller-Solger recently completed a progress report on the unexpected decline of several open-water fishes (Delta smelt, longfin smelt, juvenile striped bass and threadfin shad) in the Delta. The emerging conclusion is that the decline was caused by multiple and often interacting stressors. There are a number of factors in the Delta impacting the population and survival of native fish species.

Often referred to as “stressors,” these include wastewater pollution, agricultural run-off, federal, state and local pumping diversions, competition from non-native fish and plant species, other pollutants, and temperature change and sea level rise due to the effects of climate change. How these stressors interact, and act independently, to impact fish species has been the center of intense study and debate over the past decade.

When the report turned to the complexity of ranking stressors, Isenberg made a plea for help.

“I’m looking for ways to approach the discussion [of ranking stressors]. There has to be a way to start rather than to have an endlessly complex array of things that have something to do with problems and no way to evaluate the range of them,” Isenberg said.

In response, Mueller-Solger explained, “What science can do for you is to present tradeoffs; what happens if I do this to the other part and what happens if I do that to this part.”

The Independent Science Board

Newly appointed Independent Science Board Chair Dr. Richard Norgaard agreed to commission a study to prioritize stressors in the Delta and to meet each month to review the science included in drafts of the Delta Plan.

Last month, the Independent Science Board was asked to prioritize the stressors in the Delta for the Council to consult during its drafting of the Delta Plan, noted by many as a difficult task.

“There is not a way to rank the stressors,” Norgaard said. “Our hope as an Independent Science Board is to provide you with a way of thinking about stressors that helps turn the battle away from ‘which stressor is more important’ into a constructive dialogue.”

The Independent Science Board will meet Jan. 12-13, 2011, to formulate a report about stressors. The group plans to present the report to the Council at the end of January.

Coequal goals

The Delta Stewardship Council was created in legislation to achieve the state mandated coequal goals for the Delta. "'Coequal goals' means the two goals of providing a more reliable water supply for California and protecting, restoring, and enhancing the Delta ecosystem. The coequal goals shall be achieved in a manner that protects and enhances the unique cultural, recreational, natural resource, and agricultural values of the Delta as an evolving place." (CA Water Code §85054)