By Wes Miliband with Kevin Harris
On February 21, the State Water Resources Control Board (SWRCB) received a letter from the California Department of Fish and Wildlife (CDFW) recommending instream flow requirements for Mill, Deer, and Antelope creeks to be implemented in the long-term flow setting process. Citing to a decline in anadromous salmonid populations, voluntary efforts involving water rights holders drawing from the creeks not producing CDFW’s desired results, and recent instream flow studies, CDFW’s instream flow recommendations implicate developing amendments to the Water Quality Control Plan applicable to the Sacramento River system.
Factual Background
Mill, Deer, and Antelope creeks are tributaries to the Sacramento River located in Tehama County, California. Mill and Deer Creeks are home to viable, independent populations of Central Valley spring-run chinook salmon (spring-run), a species recognized as threatened at the state and at the federal level. Mill, Deer, and Antelope creeks also serve as aquatic habitats for the threatened Central Valley steelhead and Pacific lamprey. Spring-run populations have been in decline since 2015. CDFW cites water diversions from the tributaries as a significant obstacle to migration by the resident anadromous salmonids.
Amid emergency drought conditions in 2014, SWRCB adopted minimum instream flow requirements to protect species of fish residing in the creeks and accommodate drought conditions. In Mill and Antelope creeks, voluntary agreements were entered between CDFW, the National Marine Fisheries Services (NMFS), and water users drawing from their respective creeks, while Deer Creek received curtailment orders from SWRCB. Affected water users believe that physical channel modifications can protect aquatic resources and provide fish passage without reducing the amount of water they are allowed to divert from the creeks.
CDFW Recommendations
CDFW’s instream flow recommendations follow a series of efforts working with water rights holders diverting from Mill, Deer, and Antelope creeks, and incorporates results of instream flow studies conducted in the creeks in recent years. CDFW completed and published instream flow studies for Mill and Deer creeks in 2017, which CDFW utilizes to support the monthly flow recommendations included in CDFW’s letter. In 2020, CDFW completed an instream flow investigation for Antelope Creek, which was also included when setting the flow recommendations in the letter to SWRCB. Using the information from these instream flow studies when setting long-term flow requirements, optimal fish passage and ecological function are sought to be protected in Mill, Deer, and Antelope creeks.
While voluntary agreements have been entered in Mill and Antelope creeks, CDFW believes that these agreements have not succeeded in securing the long-term flows required to protect aquatic species and ecological function in the affected tributaries. Since the imposition of emergency drought regulations and throughout the voluntary agreement process, threatened fish populations have continued to decline within the creeks. CDFW’s recommendations contemplate higher minimum flows (depending on water year and type) in the creeks to protect spawning fish by ensuring spawning ground availability and reducing the detrimental effect of low water levels. In light of its past efforts, and consistent with its responsibility as the state’s trustee agency for fish and wildlife, CDFW recommends that the SWRCB should include the instream flow recommendations provided during long-term flow setting processes as a tool to balance all beneficial uses of water in the creeks. Unclear is the extent to which these recommendations impact existing water rights, part of which have already contributed to flows for fisheries, thus highlighting the elusive balance between human consumptive water needs and those of fisheries (and riparian habitats).
Conclusion and Implications
California’s Department of Fish and Wildlife’s instream flow recommendations may have broader implications that reach beyond the Sacramento River. Because the Sacramento River is the largest River in California, treatment of its tributaries by regulators may be instructive throughout the state. Further, while the setting of instream flow requirements can protect aquatic species and ecological functions, human needs (i.e., municipal and agricultural uses) may also be impacted by the imposition of these requirements. However, human and fishery interests can co-exist if long-term flow setting processes are backed by reliable science and seek to balance releases and diversions with temperature controls, while considering the habitat necessary to support spawning fish populations.
The instream flow recommendations also implicate the Water Quality Control Plan Update, being developed by State Water Resources Control Board, for the San Francisco Bay and Sacramento-San Joaquin Delta Estuary. Previous versions of the plan consider the protection of viable anadromous salmonid populations in the area, and list substantial diversion as a major factor in ecosystem decline. Stakeholder engagement is critical to better ensuring a viable solution and without years of contentious administrative or legal proceedings.
