Twenty-one restoration projects re-connected 8,700 acres of tidal, riparian, and floodplain habitat to tidal and freshwater flows, benefiting native fish and birds.
The Measure
Restore land-water connections to increase hydrologic connectivity and seasonal floodplain inundation.
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Expectations
- Increase hydrologic surface water connectivity
- Increase the frequency of seasonal inundation
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Performance Metrics
- Acres of areas hydrologically connected to fluvial and tidally influenced waterways
- Acres of nontidal floodplains that inundate at least every two years
Restoration Projects that Contribute to Connectivity in the Delta
The map and table below display habitat restoration projects within the Sacramento-San Joaquin Delta and Suisun Marsh that are completed, in progress, and planned since 2013. These projects restore land-water connections and are classified as riparian, floodplain, and tidal wetland habitat types. Projects restoring non-tidal wetland habitat are included to provide a snapshot view of overall habitat restoration in the Delta.
Next data update: This performance measure will be updated on an annual basis.
Yolo Bypass Salmonid Habitat Restoration and Fish Passage Project
Also known as the Big Notch Project, this project improves fish passage and increases floodplain fisheries rearing habitat in Yolo Bypass and the lower Sacramento River basin. This project broke ground in June 2022 and is expected to be operational in 2025. It will help meet the inundation and connectivity acreage targets of this performance metric.
Learn More
Since the 1800s, 91% of historical wetland habitat in California has been lost, including 95% of the Central Valley floodplain. In the Sacramento-San Joaquin Delta, most of these wetlands and floodplains have been drained and converted to agricultural land use. Although most of the natural wetlands no longer remain, some agricultural land, floodways, and floodplains can provide similar functions, including increased aquatic food production and transfer of nutrients to the ecosystem. However, for these functions to be maintained or restored, areas must be hydrologically connected via surface water and inundated by water for at least part of the year.
Restoring land-water connections to provide the biological benefits of floodplain inundation requires two components: 1) surface water connectivity for water to flow onto land; and 2) sufficient flow of water to inundate these connected areas.
This performance measure tracks the area of land hydrologically connected to Delta waterways and how much of this area becomes inundated during a two-year interval. Performance Measure 4.2a tracks Yolo Bypass inundation frequency and duration. These two performance metrics both track inundation, highlighting the importance of water connecting to land for native species population health.
1 Area that is inundated on a two-year recurrence frequency and is connected via surface water to the fluvial river or tidal system.
2 There is no depth threshold for the inundation analysis, as inundation occurs at any depth. While depth of inundation is important for ecological processes, the available data do not include depth measurements.
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. The recommendations 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.
Strategy
- Restore Ecosystem Function
Recommendations
N/A
Metric
Acres within the Delta and Suisun Marsh that are:
- Hydrologically connected to fluvial and tidally influenced waterways.
- A nontidal floodplain1 area that inundates2 at least once every two years.
Baseline
As of 2018:
- An estimated 75,000 acres of land are physically connected to the fluvial river and tidal system.
- Approximately 15,000 acres of the connected land were inundated at a two-year interval, calculated as a long-term average for 1985-2018.
Target
By 2050:
- Additional 51,000 acres are added to the 75,000-acre baseline that is physically connected to the fluvial river and tidal system, for a total of 126,000 acres.
- At least an additional 19,000 acres of nontidal floodplain area is inundated on a two-year recurrence interval, for a total of 34,000 acres.
To provide a short-term assessment of progress toward the inundation and connectivity targets, intermediate milestones are set for evaluation every decade. The following interim milestones are established on an assumed linear progression toward the 2050 target date.
| Metric | Baseline (Acres) |
2030 Total Area (Baseline Acres Plus Net Increase) |
2040 Total Area (Baseline Acres Plus Net Increase) | 2050 Total Area (Baseline Acres Plus Net Increase) |
| Hydrologic Tidal and Fluvial Connectivity | 75,000 | 92,000 | 109,000 | 126,000 |
| Nontidal Inundation | 15,000 | 21,400 | 27,700 | 34,000 |
Although linear progression is presumed for setting interim milestones, many management and environmental uncertainties exist, such as climate change and frequency of drought in implementing restoration projects and achieving the target acres of inundation and connectivity. Interim assessments of the performance measure will consider the existing state of the restoration in the Delta and disclose conditions impacting the rate of restoration interim progress.
Data Sources
Connectivity: Multiple data sources are used to track habitat restoration projects include:
The Future of Restoration in the Delta Numbers - DPIIC Presentation by Dylan Chapple
The Delta Science Program’s Adaptive Management program is credited for the initial compilation of this dataset.
To determine the number of acres that count toward that connectivity metric, the dataset was screened for restoration projects whose primary habitat type was classified as tidal, floodplain, or riparian and for projects that had been completed in or after 2018. Project acreage was counted based on the number of acres listed for the primary habitat type.
Inundation: Inundation acreage from the established baseline has not been calculated to date. Datasets used to establish the baseline include:
Landsat Dynamic Surface Water Extent
National Aeronautics and Space Administration (NASA) and Indian Space
European Space Agency SENTINEL Program
Surface Water and Ocean Topographic Mission (SWOT)