Consensus Report

Each report is produced by a committee of experts selected by the Academy to address a particular statement of task and is subject to a rigorous, independent peer review; while the reports represent views of the committee, they also are endorsed by the Academy. Learn more on our expert consensus reports.

Report in Brief >>

California's draft Bay Delta Conservation Plan—a draft plan to conserve habitat for endangered and threatened species, while continuing to divert water to agriculture and domestic water users in central and southern California—is incomplete and contains critical scientific gaps. The Bay Delta is a large, complex ecosystem that supplies water from the state's wetter northern regions to the drier southern regions, and also serves as habitat for many species. The Bay Delta Conservation Plan describes a proposal to construct a tunnel or canal to divert water from the northern Delta to the south, thus reducing the need to convey water through the Delta. This report reviews the use of science and adaptive management in the draft Bay Delta Conservation Plan and identifies opportunities to develop a more successful plan.

Key Messages

  • The Bay Delta Conservation Plan states that an effects analysis—defined as a systematic, scientific look at the potential impacts of a proposed project on endangered and threatened species, and how those species would benefit from various conservation actions—is an important component of a habitat conservation plan. However, the effects analysis for the Bay Delta Conservation Plan is still in preparation and was not included in the draft plan reviewed in this report, resulting in a critical gap in the science. Without the effects analysis, it is difficult to evaluate alternative mitigation and conservation actions.
  • The purpose of the Bay Delta Conservation Plan is not clear, making it difficult to properly understand, interpret, and review the science that underlies the plan. Although the plan states it is an application for the incidental take of listed species as a result of the proposed water diversion project, it also sets out the goals of providing a more reliable water supply for the state of California and protecting the Delta ecosystem. Because different processes would be used to fulfill these different purposes, the panel concluded that it would be difficult to evaluate the Bay Delta Conservation Plan without clarification of the plan's goals.
  • Many scientific studies have sought to understand the hydrologic, geologic, and ecological interactions in the Delta, efforts that constitute the scientific foundation of the Bay Delta Conservation Plan. However, it is not clear how the authors of the Bay Delta Conservation Plan synthesized this material and incorporated it into the draft plan.
  • Adaptive management programs cannot be fully described in advance, because the program must evolve as it is implemented. However, some aspects of the program could be laid out more clearly than they were in the draft Bay Delta Conservation Plan, the panel concluded. The plan developers would benefit from experience with adaptive management efforts in other large-scale ecosystem restoration projects, such as the Comprehensive Everglades Restoration Program.
  • The management of the Bay Delta Conservation Plan reflects the differing perspectives of the many stakeholder groups involved. Unless the management structure is made more coherent and unified, the final product may continue to suffer from a lack of integration, and in an attempt to satisfy all discrete interests it may fail to achieve its goals. The panel suggests the agencies responsible for implementing the plan review other examples of large scale restoration programs that have been developed and implemented.