Environmental Flows in California

By Alyssa Obester, Sarah Yarnell, and Ted Grantham

The California Environmental Flow Framework was recently highlighted in the 2020 Water Resilience Portfolio to address the seemingly impossible task of establishing of how much water our rivers and streams need to support healthy ecosystems. While many methods for setting environmental water needs exist, the Framework provides a unique and flexible approach that is applicable statewide.

What is the California Environmental Flows Framework? Developed by a workgroup of researchers and agency staff from across the state, the Framework is a guidance document for developing ecological flow criteria, which describe the timing and magnitude of streamflow required throughout the year to support native species and their habitat. These criteria are defined according to the natural range of hydrologic conditions under which native species have evolved, but can be refined under the Framework to prioritize specific ecosystem management goals (e.g., endangered species needs) or to accommodate novel ecosystem conditions. The Framework also describes desirable practices for making decisions on how to balance ecological flow needs with human water uses.

Unlike other environmental flow assessment methods, the Framework offers an approach that:

  • Considers all aspects of the annual hydrograph, focusing on flow components linked to ecological function in streams (functional flows);
  • May be applied across a broad diversity of geographic and water management settings and desired ecosystem goals;
  • Provides tools and guidance for developing ecological flow regimes;
  • Provides guidance for balancing multiple management objectives; and
  • Provides recommendations for, and examples of monitoring and adaptive management programs.
Fig. 1. Streams in California with existing instream flow requirements, data provided by the State Water Resources Control Board’s Cannabis Policy Program’s mapping tool.

Protecting stream flow is essential to the persistence of native species and health of our freshwater ecosystems. To date, however, few streams in California have legally recognized environmental flow protections (Fig. 1), where regulators have set the amount and timing of water to be left instream to support fish, wildlife, and habitat maintenance and creation. Where environmental flow protections do exist, they are limited typically in geographic scope and generally are focused on the needs of a few endangered species and fail to consider ecosystem needs holistically.

A key action recommended in the Governor’s Water Resilience Portfolio is protecting and enhancing natural systems. To do so requires a broad understanding of the flows needed to support aquatic and riparian species and tools to translate this knowledge into management practice. The California Environmental Flows Framework provides a means of doing so. A draft of the Framework will be available for public review in early summer 2020. Further information about this effort can be found at CEFF.ucdavis.edu.

Further Reading

California Environmental Flows Framework Technical Team. (2018). The California Environmental Flows Framework website. http://ceff.ucdavis.edu.

California Natural Resources Agency, California Environmental Protection Agency and Department of Food and Agriculture. (2020). Draft Water Resilience Portfolio.

Yarnell, S.M., Stein, E.D., Webb, J.A., Grantham, T., Lusardi, R.A., Zimmerman, J., Peek, R.A., Lane, B.A., Howard, J., and Sandoval-Solis, S. A functional flows approach to selecting ecologically relevant flow metrics for environmental flow applications. River Res Applic. 2020; 1– 7. https://doi.org/10.1002/rra.3575

Yarnell, S., Obester, A., Grantham, T., Stein, E., Lane, B., Lusardi, R., Zimmerman, J., Howard, J., Sandoval-Solis, S., Henery, R., and Bray, E. (2018). Functional flows for developing ecological flow recommendations. California Water Blog.

Alyssa Obester is a researcher at the UC Davis Center for Watershed Sciences. Sarah Yarnell is a senior researcher at the Center for Watershed Sciences. Ted Grantham is faculty at the University of California, Berkeley and an affiliate of the Center for Watershed Sciences. Alyssa, Sarah, and Ted are part of a larger technical group that is continuing to work on implementing a functional flows approach across California via the Environmental Flows Workgroup, a sub-group of the California Water Quality Monitoring Council. Technical group members include individuals from UC Berkeley, UC Davis, Utah State University, UC Agriculture and Natural Resources, Southern California Coastal Water Research Project, The Nature Conservancy, California Trout, California Department of Fish and Wildlife, and the State Water Board.

About Andrew Rypel

Andrew L. Rypel is a Professor and the Peter B. Moyle and California Trout Chair of coldwater fish ecology at the University of California, Davis. He is a faculty member in the Department of Wildlife, Fish & Conservation Biology and Director of the Center for Watershed Sciences.
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1 Response to Environmental Flows in California

  1. tryg sletteland says:

    As stated above, “Protecting stream flow is essential to the persistence of native species and health of our freshwater ecosystems.” I look forward to reviewing a draft of The California Environmental Flows Framework when it becomes available in summer, 2020.

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