San Joaquin River, SWRCB, Vernalis Adaptive Management Plan (VAMP), Water Quality, Water Quality Control Plan (2006)

Challenges and opportunities for the San Joaquin explored at State Water Resources Control Board proceeding

Courtesy of SWRCB.

Last week the State Water Resources Control Board held a two-day proceeding in Sacramento to gather information related to salinity and flow objectives for the San Joaquin River and southern Delta — generally, the portion of the Delta located south and west of Stockton (pictured in the map at right).  The format of the proceeding, which consisted of expert panels organized around broad topics, resembled last year’s flow criteria hearings, providing board members with an opportunity to interact directly with panelists and some opportunity for panelists to respond to each other’s testimony.

Despite similarities in format, the context for this effort differs from that of the flow criteria.  The flow criteria, which were intended to inform and guide but not strictly bind, were prepared in response to a unique legislative provision requiring that the State Board adopt criteria to describe the flows needed to protect public trust resources in the Delta.  Last week’s hearing, however, was an initial stage in an extended process that will culminate in new objectives for the southern Delta, revising those described in the 2006 Bay-Delta Water Quality Control Plan (WQCP).  Once developed, the revised objectives will bind whichever entities are called upon to contribute to their implementation.  But if history is any indication, even so-called binding objectives are negotiable — or at least postponable.

The 1995 WQCP prescribed flow objectives for the southern Delta to protect fish and wildlife, including spring pulse flows on the San Joaquin released for the benefit of Chinook salmon, but these objectives later evolved into the Vernalis Adaptive Management Plan (VAMP).  This previous post compares these different sets of flow objectives.  In addition, there are agricultural salinity objectives that focus on Vernalis and three interior stations in the southern Delta: an April-August objective of 0.7 mmhos/cm (dS/m) electrical conductivity (EC), and a September-March objective of 1.0 EC.  These are the basic flow and salinity objectives that the State Board will evaluate and revise in its upcoming effort.

A draft report (PDF) was released last fall, detailing the technical methodology that board staff has applied so far to this problem.  The purpose of last week’s hearing was to call upon the expertise of panelists who praised and critiqued different aspects of the report.  This discussion will help inform upcoming environmental review, while also educating both staff and board members about the scientific premises that should underpin any future management, legal or policy decisions.

In order to restore some semblance of ecological balance and give native fish species a chance to recover from a trend of overall decline, the report essentially proposes that the system be managed in a way that mimics the ebb and flow of the natural hydrograph, capturing some of the variability to which the native fishery has adapted.  Flow objectives would be expressed as a minimum percentage of unimpaired flow, with alternatives ranging from 20 to 60 percent of unimpaired flow.  In addition, a certain quantity of flow would be used to achieve salinity objectives.  This management scheme clearly has implications for water supply along the San Joaquin and its tributaries.  While the report does attempt a conservative overestimation of what those implications could be — between 111,000 and 1.9 million acre-feet, depending on the alternative and year type — this is mainly a mathematical exercise that defers detailed analysis of specific impacts.

Although this effort is distinct from the flow criteria, the flow criteria appear to have left their mark nonetheless, influencing the State Board’s thoughts about how the existing southern Delta objectives should be changed.  In upcoming posts, I hope to write more about interesting aspects of the draft report, and describe in more detail some of the issues we may expect to see the State Board tackle in future environmental review.


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