West Delta Program

The West Delta is an extremely important asset that protects against migration of salt water ensuring water quality for upstream uses (including potable and agricultural water uses).  The West Delta also provides habitat for plants and wildlife in a geographical area with a rapidly growing population.

Because of the soil types in the West Delta (peat soils) and land management practices (farming or other practices that promote oxidation of the peat soils) over the years, land subsidence has been occurring at rapid rates. Subsidence jeopardizes levee stability and creates a larger void for saltwater penetration in the event of a levee breach creating a “Big Gulp” effect. 

We  purchased much of the land on two West Delta islands – Sherman Island (approximately 90%) and Twitchell Island (approximately 80% )— in the early 1990s in order to protect levees, ensure water quality, and create habitat. 

Research shows that utilizing certain types of plants and implementing specific land use management practices will not only limit or reduce the oxidation of peat and land subsidence, but also could sequester atmospheric carbon and/or other greenhouse gasses.  Because of this potential benefit, carbon sequestration should be a key consideration when evaluating potential land use practices.

We have implemented large-scale efforts to develop sustainable practices that sequester carbon and reduce subsidence, while also developing wildlife habitat on Sherman and Twitchell Islands. We work closely with stakeholders to develop specific projects in a timely manner to achieve these goals.

  • Twitchell Island – Rice Project
  • Twitchell Island – East End Wetland Restoration
  • Twitchell Island – Setback Levee
  • Twitchell Island –15-acre Wetland Research Facility
  • Sherman Island – Mayberry farms Wetland Restoration
  • Sherman Island – Whale’s Mouth Wetland Restoration
  • Sherman Island – Setback Levee


Map showing the locations of carbon sequestration and wildlife habitat projects on Twitchell and Sherman Islands in the Sacramento-San Joaquin River. For more information about the projects, please contact Bryan Brock by email at flood@water.ca.gov.

Contact Information

Bryan Brock, P.E., Senior Engineer

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