The California Environmental Flows Framework

The California Environmental Flows Framework (CEFF) provides an approach for evaluating ecological flow criteria and options for developing ecological flow prescriptions that can accommodate a variety of stream types and biological communities, while supporting regulatory and management agency programs aimed at protecting beneficial uses for aquatic life. CEFF allows for the assessment of ecological flow criteria based on natural variability of ecologically-relevant functional flow metrics. It guides the user on selecting appropriate methods for refining these criteria to develop ecological flow prescriptions given regional or site-specific stream conditions, management goals, and desired ecological outcomes.


Project Description:

Identifying ecological flow prescriptions (i.e., recommendations) is necessary for the protection of freshwater ecosystems and the associated services they provide to society. Multiple state and local agencies across California share responsibility for quantifying flows needed to protect and improve the health of freshwater ecosystems. Yet, the vast majority of streams and rivers in California do not have ecological flow prescriptions, mainly due to the substantial resources required to evaluate ecological flow needs at a high number of diverse locations. Historically, where ecological flow criteria have been developed, efforts have been poorly coordinated and have resulted in fragmented, inconsistent, and ultimately ineffective protection of freshwater ecosystems. To improve the coordination and effectiveness of flow management in California, this technical team has pooled data, evaluated methods, and developed a statewide approach for establishing ecological flow criteria and guidance on developing ecological flow prescriptions. The products of this effort can aid in water management decision-making processes and the development of environmental flow objectives.

The California Water Quality Monitoring Council established a statewide technical workgroup to strengthen linkages between research and agency needs and to provide support for resource managers working to secure environmental flow protections in the state’s rivers and streams. A key product of this workgroup is the development of this document, the California Environmental Flows Framework (CEFF), which provides an approach for developing consistent science-based recommendations for setting ecological flow prescriptions statewide. CEFF provides guidance, data, and tools for users to develop hydrologically representative and ecologically-relevant functional flow metrics that can be used to inform the establishment of environmental flow objectives aimed at protecting aquatic life while supporting human uses. CEFF has the following features:
  • is based on a functional flows approach that considers all aspects of the annual hydrograph, focusing on flow components that are linked to ecological function in streams,
  • has a structure that allows for the flexible development of ecological flow criteria based on reference hydrology and provides tools and guidance for developing ecological flow prescriptions,
  • can be applied across a broad diversity of geographic and water management contexts and desired ecological outcomes,
  • provides guidance for balancing multiple management objectives, and
  • includes recommendations for and examples of monitoring and adaptive management programs.
CEFF provides ecological flow criteria that support ecosystem function using reference hydrology. In addition, CEFF offers guidelines for refining ecological flow criteria aimed at supporting specific species or habitats. The resulting ecological flow prescriptions can then be used to establish environmental flow objectives that balance ecological and human water needs.

       Process for developing ecological flow criteria and prescriptions in California. CEFF process in green and blue. Orange box indicates additional  considerations stakeholders should take outside of the technical process to ultimately arrive at environmental flow objectives.
Key CEFF products:
  • Reference-based ecological flow criteria: Uses 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
Once complete, the CEFF Guidance Document will be made publically available. Further information about CEFF is provided at
Project Contact: 
Research Partners: 

Evaluating Tradeoffs in Environmental Flows

This project is building a platform for experimentation - it's meant to be something that:

  1. lets other researchers quickly build environmental flow optimization problems and get results and
  2. provides decision support for modeled instream flow allocations

More information coming soon on this page.

Additional Resources