California's Bay Delta Conservation Plan Has No Clothes

Remember the story of the emperor’s new clothes?  Two tailors promise the emperor a magnificent suit of clothes made of fabric that is invisible to those who are unworthy of their positions.  The emperor, who can’t see the fabric himself but doesn’t want to admit it, parades before his subjects.  The crowd plays along with the pretence, unwilling to speak out, until a child blurts out the truth—the emperor is wearing nothing at all! 

The parallels between this fable and the current collision of science and policy in California’s iconic San Francisco Bay-Delta are disturbing.  At issue, development of the Bay Delta Conservation Plan, intended to rescue the estuary’s collapsing ecosystem, prevent extinction of half a dozen fish species (including salmon) and improve the reliability of water supplies pumped from Delta channels to farms and cities.  The result of this five-year, $140 million effort is a draft plan that, according to its own “effects analysis,” would make the existing situation worse by further degrading estuarine habitat, harming most of the fish species it is supposed to help and increasing water diversions from this already over-tapped system. 

How could BDCP reach this point, when the Bay-Delta is one of the best studied estuaries in the world?  Even in this contentious system, there is no disagreement that many factors have contributed to the ecosystem’s decline.  Here are the major problems, the BDCP’s preliminary proposed actions to address them and a summary of what the best current science says about the likely effectiveness of those actions. 

Freshwater inflow and water management:  Like all estuaries, the Bay-Delta is dependent on the inflow of fresh water.  For many Bay-Delta fish and invertebrate species, higher inflows result in higher abundance levels: this is the strongest scientific relationship we have between any environmental variable and biological response in this ecosystem.  But water diversions, which reduce flows, have been increasing for the past several decades.  In the 2000s, diversions from the Delta reached record high levels, effectively leaving the estuary in chronic drought conditions.  The resultant degraded habitat and mortality of fish at the Delta pumps contributed to dramatic fish declines, leading to court-ordered reductions in pumping and prompting California’s State Water Resources Control Board to conclude that current levels of freshwater inflow are insufficient to protect public trust resources in the Bay-Delta.  But one of BDCP’s preliminary proposed “conservation measures” is to build a new “isolated conveyance” facility (previously known as the peripheral canal) with a new diversion in the northern Delta, and to increase the amount of water exported from the Delta by an average of 20 percent.  This increased pumping would further reduce freshwater flows to the estuary, which, according to decades of science, will worsen estuarine ecosystem conditions and reduce species abundance.   A new conveyance facility is neither inherently beneficial nor inherently harmful to the ecosystem—its impacts or benefits depend on how it would be operated.  But, the current proposal to increase diversions would clearly harm the estuary and Bay-Delta fish species. 

Habitat:  Most of the Delta’s tidal marshes and floodplains were lost a century ago when levees were constructed and wetlands drained to create farmland.  Loss of these productive habitats undoubtedly had significant negative impacts on the ecosystem back then but it is unlikely that this is a major cause of recent ecosystem or species declines.  Restoration may be desirable for a number of reasons (and, particularly floodplain restoration may provide ecological benefits), but there is little scientific evidence that tidal marsh restoration will contribute to recovery for most of the endangered fish species.  This study of Bay-Delta tidal marshes reported that there was a “high degree of uncertainty” that restoration would benefit Bay-Delta fishes and this study warned that restored tidal marshes were likely to be invaded by harmful invasive plants and fishes, which would minimize (or eliminate) benefits for native species targeted for recovery.  Despite this, the BDCP relies heavily on restoration of tidal wetland habitat and, to justify these actions, cites and misrepresents some of these same studies to claim that these conservation measures “may contribute significantly” to the food web and benefit species. 

Water Quality: Delta waters are listed under the Clean Water Act as “impaired” for a number of pollutants and studies indicate that toxic contaminants and toxic algae blooms may be a contributing factor for species’ declines.  BDCP’s conservation measures to address this problem are to provide funding for a few already-required pollution mitigation programs and to conduct limited monitoring in some areas.  Meanwhile, other BDCP actions that reduce flows would likely exacerbate blooms of toxic algae, which occur under low flow conditions. 

Food supply: Some twenty years ago, the abundance of the planktonic plants and animals that are important components of the Bay-Delta’s food web declined dramatically, the victim of the invasive overbite clam and ammonium pollution from agricultural drainage and sewage treatment plants, according to scientific research.  Food limitation has been identified as a contributor to the recent fish declines.  BDCP proposes to address this problem by restoring tidal marsh and floodplain habitats, claiming (with little scientific support) that these restored habitats will produce plankton and increase the estuarine food supply.  But, even assuming that part of the plan does work, BDCP’s plans to further reduce flows would likely improve habitat conditions for the clam and reduce dilution of ammonium pollution, exacerbating the principal causes of low planktonic food supplies in the Bay-Delta.  And, since most of BDCP’s proposed restoration projects would not be implemented for at least 20 years, the plan offers little to address this immediate problem.

Invasive species: In the Bay-Delta, invasive species are both a cause and a symptom of the degraded ecosystem.  The most harmful species—the overbite clam, Brazilian waterweed and predatory warm-water fishes—thrive in stable, low flow conditions like those that now regularly occur because of excessive water diversions.  Invasive species are notoriously difficult to get rid of, particularly when environmental conditions are favorable for them: there is little evidence that chemical or physical removal control programs either reduce their abundance or improve ecosystem conditions.  Nevertheless, BDCP’s approach to this problem is to fund a few localized programs to try to suppress Brazilian water weed and predatory fish populations (but not the clam).  Meanwhile, BDCP’s plans for reduced flows and (possibly risky) tidal marsh restoration projects could worsen the Bay-Delta’s invasive species problem.

From my perspective as a scientist who has conducted research and worked on policy development in the Bay-Delta for the past 20 years, the mismatch between what the science tells us about this ecosystem and what the BDCP currently proposes for its conservation plan is … astonishing. 

But from a more jaded perspective, I suppose it’s understandable how it came to this—and an illustrative example of the dangers of disproportionately empowering some special interests in the development of a public resource management plan.  The Delta export water contractors, (the tailors in our fable) who have played a dominant role in the development of the BDCP, have developed a set of seemingly impressive, but likely ineffective, conservation measures (the emperor’s invisible suit).  Unlike the fable, however, the crowd has not been silent: reviews by scientists from government agencies, stakeholder groups, the Delta Science Program and the National Academy of Sciences have been uniformly critical. 

The BDCP is an important and ambitious effort to manage a complex ecosystem to balance environmental and human needs, but it’s hard to imagine that it can succeed without fundamental changes to its use of science to develop an effective plan.  To protect the Bay-Delta and sustainably manage California’s water resources—and to avoid further embarrassment—it’s time for the BDCP to put some scientific clothes on.

NRDC Science Center intern Catherine Corrigan-Ashe contributed to this post.