Relax Delta salinity standards A management strategy in the COEQWAL scenario library

§2 What this strategy changes

In recent years, many parties have called for the removal or loosening of the requirement that certain X2 conditions (the location of the 2-ppt isohaline) be met in August through October (“fall X2”), as originally set by the 2008–2009 Biological Opinions. Arguments for their removal include that these fall X2 actions have not had the intended benefit for Delta ecology and fish. The most recent revised USBR proposed operation released in December 2025 (“Action 5”), updating the version released in December 2024, also removes the fall X2 requirement.

This scenario deactivates the rules that set flows required to meet the fall X2 salinity conditions. Other Delta flow and salinity requirements are still in place and may control system behavior regardless of whether the fall X2 requirement is in effect.

§3 The configuration in detail

The table compares the eight operational fields that define this strategy against current operations — the strategy that represents existing operational rules, recent (2020) land use, and TUCPs. Rows that match current operations are shown in light gray; rows that differ are highlighted.

§4 Lineage and source

This strategy was developed by the COEQWAL team using the Current Operations scenario as the base from which changes were made. The key change in this scenario is the deactivation of the flow requirements tied to the fall X2 salinity standards. It is otherwise unchanged from the COEQWAL Current Operations scenario (i.e. it uses the 2020 land use and DWR’s historically adjusted hydrology). The CalSim model files for this strategy are referenced by the run IDs in the references note at the end of this brief.

§6 What this doesn't say

This brief describes a scenario representation in CalSim, not a real-world policy proposal or implementation plan. The strategy as modeled may not capture all details necessary to support direct translation to actual operations. The brief does not predict, evaluate, or recommend any outcome — it describes what the scenario changes about CalSim's representation of the system. For what the model produces under this strategy, see the result briefs referenced in §7.

§7 See results for this strategy

To see modeled outcomes under this strategy across all nine key outcomes at the reference hydroclimate, see the The Delta as a living place theme brief.

To see outcomes at a specific location of interest, see the relevant LOI briefs — particularly those for Delta locations.

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