Delta Ecosystem Enhancement

Photo of Twitchell Meadow

A view of the Twitchell Willow Canal Mitigation Site and Twitchell Meadow Enhancement site. Prior to planting the site in 2016, DEE performed weed maintenance in 2015 and will continue weed maintenance through 2021.

What does the Delta Ecosystem Enhancement Office do?


The Delta Ecosystem Enhancement (DEE) section is an interdisciplinary team of scientists and engineers who develop, enhance, and maintain ecologically effective habitats that benefit the overall ecological health of the region and its native species.


The Delta Ecosystem Enhancement section operates as the environmental arm of the Delta Levees Program. It’s primary role is providing environmental oversight for Delta Levees Program-funded Reclamation District projects. Staff review and manage habitat mitigation, enhancement, and demonstration projects. The primary objective of these projects is to provide habitat and ecosystem benefits (such as improved hydrology and nutrient supply) for native terrestrial and aquatic species.


We work directly with the Division of Flood Management’s Delta Levees Program in partnership with staff in the California Department of Fish and Wildlife's Delta Levee Habitat Improvement Program; reclamation districts; and other government and local agencies. Our environmental responsibilities arise from the State's support for mitigating environmental effects of levee maintenance and habitat improvement in the Delta under the California Water Code.

Foundations in State Law

The Delta Levees Subventions Program was authorized in 1973 and reimburses local levee maintaining agencies in the legal Delta for a portion of their levee maintenance costs. Following the historic floods of 1986, the Subventions Program was expanded, and a second program, known as Special Flood Control Projects ("Special Projects Program"), was added in 1988 to provide state support for major levee repair and reconstruction work in the eight western Delta Islands considered critical to maintaining water supply.

Legislative Actions

• CA Water Code §12314(c-d) from SB 34 (enacted March 11, 1988)
• CA Water Code §12987(c-d) from AB 360 (enacted September 19, 1996)
• Excerpt from SBX7 1 Legislation, Ch 2 Delta Policy (c): Provided supplemental guidance for SB 34 program activities, provided $3 million to DFG for environmental construction projects, and required the preparation of an MOU between DWR, DFG, The Resources Agency, and The Reclamation Board to coordinate the agencies' involvement in carrying out the Program's projects.
• CA Water Code §83002(b)(5) from 2009 (SBX7 1)



Map of Delta Levee Program's Habitat Sites