Ecosystem, Fisheries, Flow Criteria, Public Trust, Sacramento-San Joaquin Delta Reform Act of 2009, SWRCB

An Initial Glance at the Delta Flow Criteria Process

On March 22-24, 2010, the State Water Board held a public proceeding to collect testimony that it will use this year to inform its development of Delta flow criteria.  A few weeks prior to the proceeding, written testimony and questions were submitted by various parties to the State Board.  During the proceedings, Board members had a golden opportunity to question the array of scientific experts assembled before them in the Coastal Hearing Room, in order to learn more about what sort of flows are needed to protect public trust resources in the Delta.  Although it is questionable whether they actually took full advantage of this opportunity, Board members nonetheless heard presentations and professional opinions on five main topics: hydrology, hydrodynamics, stressors, and pelagic and anadromous fish.

The Legislature has charged the State Board with developing Delta flow criteria as an early action under the Sacramento-San Joaquin Delta Reform Act of 2009 (one portion of the water legislation passed in November 2009).  Neither the hearings nor the criteria that the State Board will issue achieve the formality of an official water quality plan or water rights decision, and the allowable time for this process (nine months) is quite accelerated, especially as compared to the Board’s often glacial pace of progress.  The following section of the legislation sets forth the State Board’s task for the flow criteria:

Water Code § 85086(c)(1): For the purpose of informing planning decisions for the Delta Plan and the Bay Delta Conservation Plan, the board shall, pursuant to its public trust obligations, develop new flow criteria for the Delta ecosystem necessary to protect public trust resources.  In carrying out this section, the board shall review existing water quality objectives and use the best available scientific information.  The flow criteria for the Delta ecosystem shall include the volume, quality, and timing of water necessary for the Delta ecosystem under different conditions.  The flow criteria shall be developed in a public process by the board within nine months of the enactment of this division. …

In some ways, these flow criteria are a strange creation.  It’s not immediately clear what form the criteria should take, nor is it clear how limited or extensive a role the criteria will ultimately serve in future Delta planning.  These issues are partially exacerbated by the surrounding piece of legislation, which is often quite vague and tends to raise more questions than it answers.  I hope to begin examining some of those issues in another post in the near future.  For now, though, it’s worth taking a broad initial look at the daunting task that the State Board now faces for the next several months.

The flow criteria are sometimes characterized as a determination of “how much water the fish need.”  There is an attractive simplicity to this characterization, particularly because it seems that very question has been largely ignored over the years, as Californians have perpetually sought to increase exports.  But this characterization ultimately obscures the complexity of the State Board’s task.  The quantity of water that is needed is certainly an important part of the inquiry.  Indeed, given how severely fish populations have plummeted recently, one cannot help but come to the conclusion that under the current physical configuration of the Delta, the quantity of water now given for fish has not been sufficient to maintain the ecosystem, let alone restore it.

But the quantity of water that we allow to flow out of the Delta is not the whole story.  An equally important question is timing: when does more water need to be released to support different life stages of fish?  Given that there are multiple listed species that need protection, including both pelagic and anadromous fish, how can the different flow schedules and needs of all these fish be accommodated and reconciled?  What level of contaminant reduction is needed to ensure adequate water quality?  Another factor that is of particular importance for anadromous fish is the flow into the Delta from the tributaries.  In addition, fish must be provided with flows of suitable temperature.  Temperature, incidentally, raises just one example of potential conflict between public trust uses, in that releasing water for environmental purposes could deplete cold water pools in reservoirs, which are needed to support salmonids.

And then there is the issue of habitat.  The channelized Delta has largely eliminated the habitat that originally made the Delta such a rich, successful ecosystem.  Saving that ecosystem will probably involve restoring at least some of the diverse habitat conditions that characterized the natural Delta, including floodplains and brackish marsh, as well as establishing connections between habitats.  Habitat is a distinct issue from flow — but it is also difficult to separate the two topics because the flows needed to protect fish could vary considerably, depending on how habitat is augmented and improved.  The habitat factor thus adds uncertainty to the State Board’s task.

Finally, one important concept that is raised repeatedly in the science, and which will be critical moving forward, is the concept of variability. Before Delta islands were “reclaimed” and put to productive use, the Delta, in a state of nature, was an inherently dynamic place.  Measurable factors like flow and salinity varied with time and season in a way that supported native species, while discouraging the accumulation of invasive species.  Humans, however, have replaced this natural variability with engineered consistency and predictability.  This change was necessary to facilitate human activities, but it also had the effect of encouraging invasive species.  In particular, the operation of the state and federal projects has controlled valley floods and regularized water quality, to permit through conveyance and the pumping of freshwater from the south Delta.  Human activities, then, have essentially smoothed out the behavior of what was naturally a “messy” landscape.  This suggests that reintroducing variability will be a promising approach for restoring the ecosystem.

I hope to return to the topic of flow criteria periodically in the future, at a finer level of detail than that presented here.  But even based on this initial glance from a broad, bird’s eye perspective, it is clear that developing the flow criteria on time will be a challenging task for the State Board.


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