From the mid-1870s to the early 1900s, approximately 90 percent of the tidal wetland habitat in the Suisun Marsh (California)was diked and converted for uses such as farms and managed wetlands. As a result, the loss of tidal access has hindered the ecological processes and functions critical for sustaining a healthy aquatic ecosystem, and has created a lack of support for the Bay-Delta aquatic foodweb. The loss of emergent tidal wetlands and channels has led to a reduction in the amount of potential rearing habitat for Chinook salmon, delta smelt, and splittail. Reduction and fragmentation of marsh habitats has also resulted in reduced populations of California clapper rail, salt marsh harvest mouse, and rare plants dependent on high tidal marsh and adjacent upland transition.
The Hill Slough Restoration Project will restore tidal wetlands and moist grassland habitat to approximately 950 acres of diked, low-quality seasonal and perennial wetlands. The project will consist of areas of the Hill Slough Wildlife Area that are not already fully tidal. All property in the project area is owned and managed by the Department of Fish and Wildlife (CDFW).
Ducks Unlimited will deliver this project by engineering the levee breach and restoration design, as well as subcontracting the required road improvements. Restoration efforts will re-introduce tidal action to the site by constructing eight exterior levee breaches and two internal levee breaches. The existing low-quality tule marsh will transition to perennial aquatic habitat in the deepest areas, low intertidal marsh, high intertidal marsh, and lowland alluvial habitat. The desired outcome is a self-sustaining marsh ecosystem created through restoration of natural hydrologic and sedimentation processes and reliance on natural abiotic and biological succession processes. The resulting tidal marsh will contribute to the Bay- Delta food web as well as provide valuable habitat for species reliant on the tidal areas of Suisun Marsh, and multiple species of waterfowl.
Funding sources for this project include Ecosystem Restoration Program, Kinder-Morgan, and Drought Relief Improvement Program funds. Ducks Unlimited is currently scheduled to begin construction in the summer of 2018.