Project Summary

The Alameda County Flood Control and Water Conservation District works to protect citizens from flooding while preserving the natural environment. In 2006, the District began working with an environmental and engineering consulting firm on a multi-objective flood management project, which combined the large-scale restoration of adjacent salt ponds and flood control. This project provides protection up to a one-foot rise in sea level.

Background

The District is devoted to protecting western Alameda County residents and property from flooding while simultaneously preserving the natural environment. The District is responsible for the operation and maintenance of vast flood control infrastructure, including channels, pump stations, and other facilities.  It is also responsible for planning, designing, and inspecting flood control projects, assisting in planning new developments to improve the integrity of the existing flood control system, and preserving the natural environment through public education and enforcement of pollution control regulations.

In 2006, the District began working with Philip Williams & Associates (now ESA) on a project to integrate three flood control channels with the large-scale South Bay Salt Pond Restoration Project. These flood control channels pass through the salt ponds and are separated from the ponds by levees, breaking the connectivity of the ecosystem. The firm worked with the District and the U.S. Army Corps of Engineers (USACE) to evaluate and recommend alternatives for connecting the Alameda Creek Flood Control Channel, a major flood control facility, to the adjacent salt ponds to facilitate tidal wetland restoration while improving flood protection.

Implementation

PWA used hydrodynamic modeling and geomorphic analysis of the lower reaches of Alameda Creek to evaluate options for the coastal levee flood protection, including new levee construction and removal. When the salt ponds were originally built, the USACE dug large flood channels and built levees to move water through as fast as possible. To keep this system operational, the District has needed to dredge the channels regularly. As part of their strategy, the partners planned to restore many of the adjacent salt ponds and reconnect them to the channels through levee breaching. The breeching would create new wetland habitats designed to cause tidal scour of the creek (i.e. prevent sedimentation) in order to provide a sustainable flood management approach. In the upper reaches of the watershed, the firm conducted sediment source and budget studies; the removal of sediments was intended to help restore the channel to its original flood control design.

Outcomes and Conclusions

This project aimed to create and maintain a more open floodplain, thus eliminating the need for continuous channel dredging to reduce maintenance costs, restore tidal habitat, and lower flood elevations. In addition, it acts as a climate change adaptation strategy because it allows for an increase in one foot of sea level rise before flooding.

Since 2010, the District has continued to be involved in the South Bay Salt Pond Restoration Project, working with partners such as the California Department of Fish and Wildlife, California State Coastal Conservancy, Save the Bay, and Pacific Gas and Electric to plan for and implement the restoration of salt production ponds and improve flood protection for over 590 acres surrounding the restoration area.

Citation

Kershner, J. (2021). Alameda County Flood Protection and Salt Pond Restoration [Case study on a project of the Alameda County Flood Control and Water Conservation District]. Product of EcoAdapt’s State of Adaptation Program. Retrieved from CAKE: https://www.cakex.org/case-studies/alameda-county-flood-protection-and-… (Last updated October 2021)