Functional environmental flows with reduced crop acreage and reintroduction A management strategy in the COEQWAL scenario library
This strategy combines functional minimum flow requirements at 17 locations throughout the Central Valley — tributaries plus the Delta — with reduced irrigated acreage across the Central Valley aimed at groundwater sustainability. These two actions are paired with the goal of moderating impacts to reservoir storage from the high water demands of the flow requirements with a lower overall agricultural demand.
This brief describes “functional environmental flows with reduced crop acreage and reintroduction”, one of 28 management strategies in the COEQWAL scenario library. Each strategy is simulated once under each of five hydroclimates; the references note at the end of this brief lists the model runs.
Functional environmental flows with reduced crop acreage and reintroduction specifies the same water management actions as Functional environmental flows with reduced crop acreage. The two strategies share the same CalSim 3 simulation of the water system — the same model run, not a duplicate. They differ in one action that is not a water management action: reintroduction of winter-run Chinook salmon to cold-water habitat upstream of Shasta Dam. Reintroduction enters the modeling through the winter-run life cycle model, not through CalSim 3, so modeled results differ from Functional environmental flows with reduced crop acreage only for the winter-run salmon key outcome. Results for the other eight key outcomes are identical by construction.
§2 What this strategy changes
The strategy combines two changes. The first is the functional-flows requirement set: minimum flow requirements at 17 locations throughout the Central Valley, developed by the COEQWAL eflows team from natural-flow estimates, with selected seasonal components added and scaled according to expected water availability. In this combination the requirement set includes the downstream main stems and Delta outflow, not only the tributaries. The second change is the use of a reduced irrigated agriculture footprint that reduces irrigation demand across the Central Valley. Reductions in irrigated agriculture were developed for the Reduced Crop Acreage scenarios to stabilize groundwater levels and are used without additional modifications here.
The second is a reduction in irrigated acreage across the Central Valley, set according to historical groundwater decline in each demand unit, with reduced acreage replaced by an unirrigated “native vegetation” land-cover type. Groundwater pumping is limited indirectly, through the reduced demand.
The goal of pairing the flow and groundwater management actions is to offset the high water demands of the functional-flows requirements with a lower overall system demand, to mitigate extreme reservoir drawdown.
§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.
| Aspect | Current operations | This strategy |
|---|---|---|
| TUCP actions | Active | Active |
| SGMA actions | None | Reduce irrigated acreage for entire Central Valley |
| Land use | 2020 LandIQ | 2020 LandIQ with reduced ag land use in select WBAs/DUs across the Central Valley to mitigate groundwater decline |
| Delta regulations | Standard | Standard |
| BiOps | 2019 / 2020 ITP | 2019 / 2020 ITP |
| Infrastructure | Standard | Standard |
| Flows | Standard | Functional flows requirements at 17 locations (tribs+Delta) |
| Allocation / priorities | Standard | Standard |
§4 Lineage and source
This configuration was created by the COEQWAL team by combining the functional-flows study with the reduced-acreage land use of the Central Valley groundwater strategy. It is built on the COEQWAL Current Operations scenario using DWR's adjusted historical 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 Rivers, salmon and the Delta ecosystem theme brief.
To see outcomes at a specific location of interest, see the relevant LOI briefs — particularly those for locations on the Sacramento and San Joaquin tributaries and for groundwater basins in the Central Valley.
References — model runs
Each strategy is simulated once under each of five hydroclimates. The table lists the model run behind this strategy and the current-operations run it is compared against, for each hydroclimate, so any reader can trace this page to specific CalSim runs. The identifier this brief carries for each hydroclimate ends in -R, which is the web platform's scenario identity for this strategy; the CalSim 3 run underneath it is the run for Functional environmental flows with reduced crop acreage, the same identifier without the suffix, s0032 under the historical hydroclimate.
| Hydroclimate | This strategy | Current operations |
|---|---|---|
| Historical hydroclimate (adjusted) | s0032-R | s0020 |
| Moderate climate stress (EC-Earth3-Veg) | s0145-R | s0134 |
| Moderate-high climate stress (cc50) | s0073-R | s0047 |
| High climate stress (cc95) | s0093-R | s0056 |
| Extreme climate stress (TaiESM1) | s0119-R | s0108 |