California Environmental Flows Framework

Summary: 
Flow alterations are a significant driver of species population declines and biodiversity loss in California and globally. When stream flows are altered by human intervention, a wide range of physical and biological processes can be affected, triggering fundamental changes to habitat condition, and the distribution, diversity, and abundance of species. Ensuring the preservation of key flow components can improve riparian and freshwater ecosystem health by restoring physical processes and habitat conditions.

Flow alterations are a significant driver of species population declines and biodiversity loss in California and globally. When stream flows are altered by human intervention, a wide range of physical and biological processes can be affected, triggering fundamental changes to habitat condition, and the distribution, diversity, and abundance of species. Ensuring the preservation of key flow components can improve riparian and freshwater ecosystem health by restoring physical processes and habitat conditions.

Multiple state and local agencies across California share responsibility for setting flow criteria and prescriptions that protect and improve the ecological health of California’s water resources. These approaches historically have not been coordinated at the statewide level, resulting in fragmented and siloed flow management programs. Consequently:

  • There is no overall framework or guidance for estimating flow criteria,
  • Agencies tend to focus on site-specific solutions, instead of holistically managing the health of California watersheds,
  • Environmental flow data are not readily available or comparable across the state,
  • Improving coordination across California is a challenge,
  • Environmental conditions and pressures vary widely, as do the priorities and capacities of agencies responsible for water resource management.

In 2016, a group of experts self-organized to pool knowledge and data, evaluate methods, and ultimately develop a statewide framework for determining environmental flow criteria for California. The strategy is organized into an approach that varies in scale and detail.

The framework will provide a set of functional flow criteria for all streams in California and a technical guidance document for estimating ecological flow prescriptions.

                                                       

Process for developing ecological flow criteria and prescriptions in California. CEFF process in green and blue (sections 2 and 3). Orange box indicates additional considerations stakeholders should take outside of the technical process to ultimately arrive at environmental flow objectives (section 4).

Key CEFF products:

  • Reference-based ecological flow criteria: Use the California natural stream classes and the functional flows approach to set flow criteria statewide
    • Statewide applicable method to set flow criteria protective of river-dependent ecosystems
  • Refined ecological flow criteria and ecological flow prescriptions: Provide guidelines for estimating ecological flow prescriptions depending on the regional, local or site-specific context
    • A tailored approach that incorporates specific environmental and water management factors and priorities

 

The Technical team will continue communicating and collaborating with diverse partners at the state and local level engaged in flow management via the Environmental Flows Workgroup, a sub-group of the California Water Quality Monitoring Council comprised of state and federal agencies with responsibility for environmental flows through their various programs and authorities.

 

 

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