California Environmental Flows Workgroup

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The mission of the California Environmental Flows Workgroup is to advance the science of ecological flows assessment and its application for supporting management decisions aimed at balancing natural resource needs with consumptive water uses to establish environmental flows. The mission will be accomplished by providing a forum for coordination and technical exchanges among government agencies, academic institutions, tribes, and non-governmental organizations in California focused on understanding environmental flow needs and establishing ecological flow criteria grounded in science. The workgroup will strive to improve agency and public access to ecological and environmental flow data, information and tools related to ecological flow assessments, and to provide a common vision for use of tools and science-based information to support sound decision making.


Natural resource managers are faced with the complicated task of protecting and restoring a broad suite of ecological functions and public values to rivers while accounting for other competing beneficial uses. A good understanding of how instream flow levels and regimes relate to the many beneficial uses, values and services of rivers (e.g., flood mitigation, water supply, biological productivity, species support, recreation) and the scale of alteration from the natural condition, is necessary for informed river management.

Instream flows are defined as the volume of water in a stream to adequately provide for instream uses within the stream channel (i.e., aquatic organisms and riverine processes). Instream flows are often divided into ecological flows and environmental flows.

Ecological flows are defined as a set of flow metric values necessary to determine a flow regime that sustains ecological endpoints (habitat processes, ecological functions, or species life history stages) within a lotic water body and its margins.

Environmental flows, on the other hand, are defined as ecological flow prescriptions adjusted to consider and balance other competing human uses to produce a flow regime that balances human and ecological needs. Environmental flows are often referred to as “balanced” flow levels allowing for hydrologic alteration due to uses other than the environment or ecosystem. However, environmental flows generally mimic patterns of the natural flow regime to achieve desired ecological outcomes.

California Environmental Flows Workgroup Charter

More Information

For additional information on the California Environmental Flows Workgroup, please email:

Dan Schultz at

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