California Environmental Flows Framework

Sarah M. Yarnell (Project Contact)
Robert Lusardi
Ryan Peek
Nick Santos
Alyssa Obester
Project Description

Identifying ecological flow criteria 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 environmental 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, a technical team has pooled data, evaluated methods, and developed a statewide approach for establishing ecological flow criteria and guidance on developing environmental flow recommendations. The products of this effort can aid in water management decision-making processes and the development of environmental flow prescriptions.

Image of river
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 the California Environmental Flows Framework (CEFF), which uses a Functional Flows approach to develop consistent science-based recommendations for setting ecological flow criteria statewide. CEFF provides guidance, data, and tools for users to determine hydrologically representative and ecologically-relevant functional flow metrics that can be used to inform the establishment of environmental flow recommendations 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 determination of ecological flow criteria based on reference hydrology and considerations of physical and biological constraints, and provides tools and guidance for developing environmental flow recommendations,
  • can be applied across a broad diversity of geographic and water management contexts, and
  • includes recommendations for monitoring and adaptive management programs.

CEFF provides ecological flow criteria that support ecosystem functions using reference hydrology. In addition, CEFF offers guidelines for considering physical and biological constraints within a stream system and developing environmental flow recommendations that balance ecological and human water needs.


Environmental Flows Framework diagram
Overview of the California Environmental Flows Framework process.
Further information about CEFF is provided at
Project Status