Creating safe fish migration paths between the Pacific Ocean and Sierra Nevada headwaters improves threatened species' survival.

The Measure

This measure has two parts:

  1. Remediate fish passage at priority barriers and select large rim dams in the Delta Watershed; and
  2. Screen priority diversions along native, anadromous fish migration corridors in the Sacramento-San Joaquin Delta and Suisun Marsh.
  • Expectations

    • Improve fish migration passages
    • Reduce fish entrainment
    • Enhance aquatic habitat connectivity
    • Contribute to anadromous species recovery
  • Performance Metrics

    • Prioritize fish passage barriers 
    • Select large-rim dams
    • Screen unscreened diversions along native, anadromous fish passage corridors

Priority Fish Passage Barriers

This graph shows the total number of fish passage barriers identified as agency priorities and those being remediated and open for fish migration.  

Fish passage barriers are prioritized by the California Department of Fish and Wildlife (CDFW) in the 2018 Priority Barrier List and the California Department of Water Resources’ (DWR) in the Central Valley Flood Protection Plan (CVFPP) Conservation Strategy for Priority Barriers. The CDFW Priority Barrier List is updated annually while the DWR Conservation Strategy for Priority Barriers will be next updated in 2027. The target is a 100% remediation of priority barriers by 2030. 

Fremont Weir Adult Fish Passage project

The Fremont Weir Adult Fish Passage project is a project that aimed to improve fish passage at Fremont Weir in the Upper Yolo Bypass. The project made the existing fish ladder wider and deeper and provides sufficient upstream passage to the Sacramento River for adult salmon and sturgeon. It is one of the priority barriers listed by the CDFW and DWR.

Fremont Weir
Figure: Fremont Weir in the Upper Yolo Bypass

Table of All Priority Barriers Identified in Both CDFW and DWR Priority Barrier Lists

This table lists all the priority barriers identified in the CDFW’s 2018 Priority Barrier List and the DWR CVFPP's 2016 Conservation Strategy. Further discussion on how these priority barriers are prioritized can be found in the accordions below. 

Next data update: Both visualizations (bar graph and table) will be updated annually at the end of the calendar year. 

Priority Rim Dams in the Delta Watershed

Rim dams are large dams along the rim or edge of the Delta watershed and the Sierra Nevada mountains. The 2014 National Marine Fisheries Service Central Valley Recovery Plan for Central Valley Salmon and Steelhead identifies fish passage remediation actions at the following rim dams shown in the map below. This map shows the priority rim dams tracked in this performance measure. Each point corresponds to the location of the large rim dam. 

These large rim dams are to be 100% remediated by 2050. This metric will depend on future or current feasibility studies being completed and fish passage programs being implemented. If feasibility studies find that fish passage remediation be infeasible, then any other additional efforts for that specific rim dam will be tracked. 

Next data update: Status of fish passage remediation at these rim dams will be updated at the end of every calendar year.

The Delta serves as a migration corridor for all anadromous fish species in the Central Valley. Adult salmon migrate through the Delta as they return to the rivers they were born in. Young salmon use the Delta for their outmigration from the upstream rivers to the ocean, for rearing and growing. Instream barriers to fish passage and unscreened water diversions impede migratory movements and adversely affect overall species survival. Most of the fish passage barriers are located upstream in the Delta watershed where these structures limit or cut off access to spawning grounds and areas of refuge from predation. Remediating fish passage barriers throughout the Delta watershed opens in-stream migration corridors, restores aquatic habitat connectivity, and contributes to migratory fish recovery. Similarly, screening of unscreened water diversions prevents fish from being drawn into diversion pipes, reduces fish mortality, and improves aquatic habitat. Fish passage remediation means providing upstream and downstream passage to migratory fish by constructing, modifying, or removing barriers. For rim dams, remediation means implementing a long-term passage program that may include the capture, transport, and release of fish at different life stages. For unscreened diversions, remediation means screening the diversion so that juvenile and adult fish are physically protected from entrainment.

While there are many fish passage barriers and unscreened diversions located within the Delta watershed, the CDFW and DWR prioritize the most important barriers to remediate.

This performance measure tracks the progress in remediating the priority fish passage barriers, rim dams, and unscreened diversions.

The CDFW and DWR have different methods of barrier/diversion prioritization but have the same goal of providing fish passage to migratory fish.

The CDFW’s Priority Barriers Lists prioritized barriers statewide based on the following criteria.

  1. High likelihood to improve migration for anadromous species
  2. Availability of recent data of fish and habitat
  3. Willing partners and land access
  4. Known political support at a local, State, or national level
  5. The site is a barrier to a federal recovery plan "core" population
  6. The watercourse is an eco-regional significant watershed
  7. Thee CDFW is committed to monitoring before, during, and after any barrier improvement project is undertaken
  8. The site is considered a keystone barrier, meaning the barrier was the lower-most in that river or creek.

The CDFW Priority Barrier List is updated on an annual basis, with remediated barriers being removed from the list and new barriers being added to the list. Barriers that remain on the annually updated list are not yet remediated (due to factors such as funding, access, or other issues) and continue to be a priority. Remediated barriers are verified by CDFW staff before they are removed from the priority lists.

The DWR’s CVFPP contains prioritized fish passage barriers in the Central Valley Flood System Fish Migration Improvement Opportunities (FMIO) study and Appendix K of the CVFPP Conservation Strategy. The fish barriers are prioritized using the following criteria.

  1. Barrier frequency
    • Waterway hydrology – frequency of migratory corridor containing water
    • Barrier status – total barrier, partial barrier, or temporal barrier
  2. Barrier intensity
    • Barrier location in the target area – barriers are given a score to reflect their spatial distribution in the target area (highest scores for anadromous species are given to barriers farthest downstream)
    • Species diversity/presence – number of anadromous species that can reach the barrier from upstream or downstream
  3. Upstream habitat
    • Upstream miles of waterway – when comparing two or more barriers, the barrier with the most upstream miles of habitat (to the next barrier) gets the highest score
    • Type of upstream habitat – spawning, rearing, and holding habitats

The DWR’s Priority Barriers List does not consider diversions, and there are no plans to regularly update DWR prioritization lists. The lists from these studies are included because they represent the most in-depth analysis of barriers and opportunities for improvements.

The CDFW has prioritization criteria specific to unscreened diversions and develops a priority list of regional annual water diversions for screening based on the following ranking criteria.

  1. Presence of listed and at-risk species
  2. Number of other diversions in the watershed
  3. Location of the diversion
  4. Intake orientation
  5. Duration of pumping
  6. Ongoing efforts in cooperation with the diverter to screen the facility

However, due to limited surveys and access within the Delta, water diversions within lack sufficient details to be able to apply the ranking criteria to them. Therefore, a first step in prioritizing unscreened diversions within Delta is to gather the additional field data. (See recommendation ER R"H")

Each chapter of the Delta Plan includes strategies to achieve the goals of the plan. These strategies are general guidance on achieving the objective laid out in the plan and in the Delta Reform Act of 2009. Associated with these strategies are recommendations, which describe more specific and implementable actions to support the achievement of Delta Plan strategies. Strategies and recommendations may also have associated performance measures. Delta Plan performance measures track progress in achieving desired outcomes for the Delta Plan. Below are the strategies and recommendations associated with this performance measure.

  • Protect Native Species and Reduce the Impact of Nonnative Invasive Species
  • Prioritize Unscreened Diversions within the Delta
  • Fund Projects to Improve Survival of Juvenile Salmon
  • Manage Hatcheries to Reduce Risk of Adverse Effects
  • Coordinate Fish Migration and Survival Research

Priority fish passage barriers and select large rim dams in the Sacramento-San Joaquin River watershed, and unscreened diversions along native, anadromous fish migration corridors in the Delta and Suisun Marsh. This metric will be evaluated annually.


Number of fish passage barriers, large rim dams, and unscreened diversions listed in the following.

  1. CDFW 2018 Priority Barriers
  2. CVFPP 2016 Conservation Strategy (Appendix K)
  3. National Marine Fisheries Service’s Central Valley Recovery Plan for Central Valley Salmon and Steelhead (2014) with recovery actions
  4. Passage Assessment Database (PAD March 2018 version)
  1. By 2030, remediate all (100 percent) priority barriers identified in the 2018 CDFW Priority Barriers List. For subsequent updates, remediate 100 percent within 10 years of being included in the priority barrier list.
  2. By 2030, remediate all (100 percent) of the priority fish passage barriers listed in CVFPP 2016 Conservation Strategy.
  3. By 2030, prioritize all (100 percent) unscreened diversions along native, anadromous fish passage corridors in the Delta, and by 2050 screen all (100 percent) priority diversions.
  4. By 2050, remediate fish passage at all (100 percent) large rim dams in the Delta watershed.

Along with the annual evaluation and tracking of this performance measure, performance assessment in relation to interim milestones will be conducted every five years, coinciding with the Delta Plan five-year review process. The interim milestones are set to allow for assessment of short-term progress toward the performance targets.

Interim Milestones – Priority Fish Passage Barriers
  1. Interim progress will be tracked against the baseline 2018 priority list with a milestone of 50% remediated barriers by 2025. 
  2. Updates or changes to the CVFPP priority barrier list are not expected. Interim milestone is remediation of 50% of priority barriers by 2025.
Interim Milestones - Rim Dams
  1. Fish passage feasibility studies initiated, ongoing, or completed for the listed rim dams will be used to evaluate the status of remediation.
Interim Milestones - Unscreened Diversions
  1. Field data is collected at unscreened diversions, in addition to diversion size and site location, to provide additional information allowing prioritization of unscreened diversions. The large majority of Delta agricultural diversions is below 100 cfs, but large unscreened diversions located on important migratory routes may remain.

Conduct prioritization of unscreened diversions for screening priorities following CDFW statewide prioritization protocol. The prioritization process includes contribution of the diversion to the cumulative loss of fishes to the system and the impact of this contribution on fish populations, especially those of declining species.


Fish passage barriers and unscreened diversions:

  1. Use the California Fish Passage Assessment Database to obtain the annual list of priority barriers and to identify which of the 2018 priority barriers (baseline) were remediated. These details can be found under the “Notes” or “BarStatus” columns on each barrier. The same is done for the 2019 and any new priority barrier list made available.
  2. In addition, use the CVFPP five-year review for updates on fish passage barriers listed in the original 2016 document (e.g. 2022 CVFPP update).

Priority rim dams, review fish passage feasibility studies and other efforts leadings to fish passage remediation. Existing efforts being tracked include the following:

  1. Bureau of Reclamation’s Shasta Dam Fish Passage Evaluation, which includes evaluations of Shasta, Folsom, and New Melones Dams.
  2. Yuba Salmon Partnership Initiative, which includes evaluation of reintroduction to spring run chinook above New Bullards Bar Dam.
  3. Turlock Irrigation District and Modesto Irrigation District, which evaluate fish passage/reintroduction above Don Pedro Dam.
  4. Upper Mokelumne Salmonid Restoration Team, which evaluates fish passage/reintroduction above Pardee Dam.
Data Sources

California Fish Passage Assessment Database (PAD)

Central Valley Flood Protection Plan (CVFPP) Conservation Strategy

Reclamation’s Shasta Dam Fish Passage Evaluation

Yuba Salmon Partnership Initiative

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