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
Refined ecological flow criteria and ecological flow prescriptions: Provide guidelines for estimating ecological flow prescriptions depending on the regional, local or site-specific context
Once complete, the CEFF Guidance Document will be made publically available. Further information about CEFF is provided at ceff.ucdavis.edu