Restoring Tidal Wetlands in American Canyon, CA

•    Grant Recipient Organization:  Ducks Unlimited, Inc.
•    Project Title:  Restoring Tidal Wetlands in American Canyon California
•    Site Location:  American Canyon, California
•    Land Owner:  California Department of Fish and Game
•    On-the-ground Implementation Start Date:  August 1, 2009 or sooner
•    Number and Type of Jobs Created or Maintained, and Anticipated Duration:  
     * Ducks Unlimited:   20 jobs, 18 months; estimated 3,766 labor hours.
     * Contractual:  33 jobs, 18 months; estimated 5,767 labor hours.

Coastal and Marine Habitat to Benefit from the Project

Implementation of the Napa Plant Site Restoration Project near American Canyon, California will result in the restoration of approximately 1,340-acres of former salt evaporation ponds to estuarine tidal marsh. There are currently no aquatic species within the unrestored portion of project area:  the former salt ponds historically had very high salinities ranging from 170 to over 350 ppt, and dried out in the summer. The restored tidal habitat will provide salt marsh, intertidal mudflat, and channel habitat within the floodplain of the Napa River.  

This project is part of a much larger complex of restored former salt ponds in the California Department of Fish and Game’s Napa Sonoma Marshes Wildlife Area located along the northwest shore of San Pablo Bay. This tidal restoration project has important benefits and implications for the recovery of endangered fish and shorebirds. The Napa River was designated as critical habitat for steelhead in September 2005, and the Napa River population of Central California Coast steelhead was listed as threatened in January 2006. The green sturgeon was also listed as threatened in April 2006 with the San Pablo Bay designated as Critical Habitat; juvenile green sturgeon have been documented using the lower Napa River.  Other important fish species found in the lower Napa River include:  the federally listed Delta Smelt, the state listed Longfin Smelt, and federally listed Chinook salmon.

But not only fish will benefit from this comprehensive project, the project will also host numerous wetland dependent migratory bird species. The Napa Sonoma Marshes Wildlife Area and San Pablo Bay are part of the San Francisco Estuary, which is one of the most important staging and wintering habitat complexes in the Pacific Flyway.  More than 30 species of waterfowl occur in the bay including approximately 50% of the entire Pacific Flyway wintering population of diving ducks, notably one of the largest concentrations of wintering canvasbacks in North America, and the majority of the Pacific Flyway population of wintering greater and lesser scaup. Other species including marbled godwit, long-billed curlew, as well as the endangered leas tern and western snowy plover will find new nesting and foraging habitats in the resulting tidal wetland.

Project Scope

The Napa Plant Site Restoration Project (NPSRP) consists primarily of earthwork required to restore approximately 1,340-acres of diked former salt ponds to estuarine tidal marsh, and a small public access element. The tidal wetland restoration project is divided into three components:  1) North Unit, 2) Central Unit, and 3) South Unit with associated uplands designated for public access facilities.

As part of the ongoing effort, the 205-acre North Unit was restored to tidal action in October 2008 by creating a tidal breach to former salt marsh.  The initial restoration work on the 175-acre Central Unit has been completed.  The remaining work in this proposal includes creating a tidal breach, removing interior divisions between former salt ponds, and reconnecting former salt ponds to the lower Napa River. The 960-acre South Unit will be restored to full tidal connection through creation of interior slough channels and construction a full tidal connection to the lower Napa River.  The 1,135-acres in the Central and South Units will be restored under this proposal.


A variety of partners have brought this large, multi-phased project to implementation.  The State Coastal Conservancy and the Resources Legacy Fund brought together public and private funding for the development of engineering plans and environmental compliance. The Wildlife Conservation Board provided funding to Ducks Unlimited for implementation of the North Unit and one-half of the Central Unit.  Due to the ongoing California state budget crises additional state funds are unavailable. Federal ARRA stimulus funding through NOAA is being provided to complete the Central and South Units.

Long-term Ecological Outcomes

Long-term, the project will consist of a mosaic of tidal habitats, with the majority of the property, approximately 1,340 acres, consisting of mature tidal marsh habitat (including vegetated marsh, subtidal channels, and small areas of associated ecotone, seasonal wetlands, and associated marsh-upland ecotones).

Socioeconomic Outcomes

The project is anticipated to create or retain 53 jobs by generating a total of 9,533 labor hours for project implementation, with the majority occurring in the first 12-18 months of the project. Non-quantifiable socioecomic benefits would include improvements to fisheries, waterfowl hunting, and other outdoor related recreational activities, educational benefits for local Bay Area residents, kayaking, walking/cycling trails.

Project Time Line

Central Unit - Start construction:  August 2009;    End:  October 2009.

South Unit - Begin construction:  August 2009;      End earthwork:  August 2010;

Salinity reduction breach:  August 2010;     Breaching:  November 2010.



Project Introduction:  The San Francisco Bay is the largest estuary system on the Pacific coasts of North and South America, and is globally recognized for its historic and continued importance to myriad fish and other wetland-dependent wildlife species. San Pablo Bay is one of three large bays that comprise San Francisco Bay and is located in the northernmost reach, about 20 miles north of the city of San Francisco. Prior to large-scale European settlement beginning in 1850, the San Francisco Bay was ringed by extensive, miles-wide tidal marshes. By the 1950s, nearly 85% of these marshlands had been diked or filled.  In the lower floodplains of the Napa River and nearby Sonoma Creek, low-lying areas comprise approximately 40,000 acres of mudflats, estuarine and palustrine wetlands, salt ponds, riparian corridors, and vast expanses reclaimed for agriculture and development. These lower floodplains, also called “baylands,” support critical wetland and floodplain habitats for diadromous fishes, waterfowl, shorebirds, and other wetland dependent fish and wildlife species.

Near the beginning of the 20th century, most of this low-lying marshland was diked off for agricultural purposes, and in the 1950s, the proposed project site and 9,000-acres of nearby salt marsh were converted to commercial salt production. Salt production ceased in the early 1990s with the acquisition of the property by the State of California’s Department of Fish and Game (DFG). These former salt ponds are the part of the second largest restoration project in the country, known as the Napa Sonoma Marshes Restoration Project. Over 5,000 acres have already been restored by Ducks Unlimited and our partners. The NPSRP represents one the next major, shovel-ready phases of bayland restoration in the lower Napa River.

The proposed restoration project will benefit multiple threatened and endangered fish and wildlife species, particularly Coho salmon, steelhead, green sturgeon, Delta smelt, and least tern and snowy plover. The Napa River was designated as critical habitat for Central California Coast steelhead in September 2005, and the Napa River Distinct Population Segment (DPS) of Central California Coast steelhead was listed as threatened in January 2006. The Napa River has the largest remaining steelhead runs in the San Francisco Bay. The Napa River historically supported a run of 6,000–8,000 steelhead, but the run declined to an estimated 2,000 adults by the late 1960s. The current run is estimated to be less than 200 adults. Steelhead spawning has been observed in Dry Creek, a tributary of the Napa River near the proposed project. The Southern DPS of North American green sturgeon was listed as threatened in April 2006.  Juvenile green sturgeon may forage in the lower Napa River all year, and adult green sturgeon have been observed by DFG staff on various occasions. The federally endangered Delta Smelt is a well documented resident of the Napa River.  In 2000, several thousand Delta smelt were recorded in survey trawls.  However, a region wide population crash occurred in 2001, and no Delta smelt were recorded in survey trawls from 2001 through 2005.

The objectives of the proposed tidal restoration project are to restore 1,135 acres of tidal wetlands to benefit federally listed fish and wildlife species, create or maintain 53 jobs by generating 9,533 labor hours for project implementation and monitoring, and provide sustainable economic opportunities to local and regional communities of the San Pablo Bay area. Ducks Unlimited will work with our project partners to implement tidal restoration of estuarine marsh at the Napa Plant Site in order to meet these objectives. Additionally, the proposed project is coordinated with the regional goal for San Francisco Bay Joint Venture to restore 55,000 to 65,000 acres of tidal marsh habitat in the San Francisco Bay.

Restoration activities for the entire NPSRP include work on three separate hydrologic units at the Napa Plant Site:  the North Unit, the Central Unit, and the South Unit (Supplemental Information Figure 2). The North and Central Units were engineered as separate projects from the South Unit for funding purposes, and can be constructed separately.  Yet, all of the units are covered by the same environmental permits and compliance documents. The common project elements of the design for all three units include:

1)    excavating a portion of the former primary slough channel in the unit (i.e., creating a major channel to promote effective drainage of each unit),
2)    creating marsh-upland ecotone to protect levees and provide transitional habitat,
3)    protecting other levees potentially vulnerable to erosion with riprap,
4)    raising land-side (eastern) levees to provide an equivalent level of flood protection that currently provided by the levees along Napa River,
5)    selectively lowering levees to improve hydrologic connectivity with the Napa River and/or tidal circulation within the unit, and
6)    breaching each unit at or near the mouth of the former main slough channel.

The North Unit.  Work on this unit was completed and tidal action was restored to the unit by Ducks Unlimited in the fall of 2008. The North Unit now consists of 205 acres of estuarine tidal marsh habitat. Harbor seals, numerous waterfowl and shorebird species, and benthic organisms were observed using the habitat within several days of breaching. Most of the North Unit is currently intertidal mudflat. 

The Central Unit.  Completion of the 175-acre Central Unit restoration is part of this grant application. The initial partial restoration effort was completed in 2008 and funded through the California Wildlife Conservation Board (WCB).  Funding of final full restoration components is proposed herein and work can begin as soon as funding is available.  The estimated completion time is two months.  Breaching would occur in early October 2009, on a favorable tide. The components to complete the restoration work for the Central Unit include partially excavating the former main slough channel, grading pond bottoms, removing interior salt pond divisions, contouring interior levees, lowering the levee adjacent to the proposed breach location to allow overtopping at high tides, and excavating the main tidal breach.

South Unit.  Construction of the South Unit restoration constitutes of the bulk of work covered by this proposal. Construction of the South Unit can begin the opening of the endangered species construction window on August 1, 2009.  Construction of the South Unit will progress in four steps:  1) construction of interior earthwork features, 2) construction of the primary breach, 3) a pond interior salinity reduction period, 3) widening of the primary breach and creating the secondary breaches, and 4) construction of public access features.