Best Practices and FAQ

North Creek Marsh restoration.

Best Practices

The best way to protect a site from the spread of invasive Spartina is to try to prevent weed seeds or rhizomes from moving between sites. The old adage “an ounce of prevention is worth a pound of cure” applies here. Practice the “Come clean, leave clean” approach. Before your team leaves for a site, make sure all equipment – including all tools, belts, and vehicle tracks and treads – are clean. Thoroughly remove all mud, dirt, and seeds. Once your crew has finished working at a restoration site, make sure to clean all the same equipment to remove mud, dirt, and seeds before leaving.

It is not recommended to propagate and plant native Spartina without the assistance of the Invasive Spartina Project team. The process of harvesting or planting Spartina can cause unintentional hybridization and spread of invasive Spartina if not carefully planned.

If you are working on a site with water that flows into the Bay, contact the team at to work together.


The San Francisco Estuary Invasive Spartina Project (ISP) is a coordinated regional effort led by the California State Coastal Conservancy, California Invasive Plant Council, and the U.S. Fish and Wildlife Service, working with project partners to protect the Bay’s extraordinary wetlands by removing invasive species of cordgrass.

The project aims to protect healthy native tidal wetlands and unvegetated mudflats by mapping and treating invasive Spartina, to improve native biodiversity in the Bay, and to reduce impacts from invasive Spartina. The Baywide goal is to eradicate invasive Spartina phenotypes (physical forms) that cause negative impacts. For the purposes of this project, eradication is defined by three consecutive years of zero detection of invasive Spartina at a site. In addition to mapping and treatment, the project actively enhances habitat, especially to support breeding and foraging grounds for California Ridgway’s rails, by propagating and installing native plants and creating high tide refuge islands.

This project is a critical step in the regional goal of restoring 100,000 acres of healthy tidal wetlands in San Francisco Bay. Healthy tidal wetlands serve as habitat for diverse fish and wildlife species. Thriving tidal wetlands also benefit coastal communities by reducing coastal erosion, protecting against flooding and storm surges, filtering pollutants from water, sequestering carbon, and providing recreational opportunities. Invasive Spartina poses an ongoing threat to San Francisco’s wetlands with the potential for rapid expansion across mudflats and restoration sites. Learn more about the team’s vision for a healthy San Francisco Bay.

Invasive Spartina outcompetes native tidal marsh species to create a monoculture, changing the habitat significantly. It spreads rapidly across open mudflats, creating meadows of cordgrass in place of foraging opportunities for shorebirds, waterfowl, and other aquatic species. It reduces flood control capacity, as dense stands trap and accrete sediment rapidly in unnatural locations, fill in storm water drainages, and cause flooding in adjacent fields, homes, and businesses. Dense Spartina meadows can also cause “ponding” in the marsh which promotes increased mosquito breeding. The presence of invasive Spartina puts shoreline restoration projects at risk since it can block the establishment of native plants and wildlife. Read more about why invasive Spartina is a problem.

No, the native Pacific cordgrass, Spartina foliosa, is an important plant in Bay wetlands and is widespread across the region. It is one of the species the project team propagates and plants in selected marshes to enhance habitat.

However, when the native Pacific cordgrass hybridizes with the Atlantic cordgrass, Spartina alterniflora, the resulting plants create a genetic “hybrid swarm” with classic “hybrid vigor,” where the offspring has more robust characters than either parent. Compared to native cordgrass, the hybrids may have greater cover (increasing competition to the exclusion of all other native marsh plants), greater height (allows for establishment at lower tidal elevation), greater inflorescence size (allows for pollen swamping of adjacent native cordgrass, as well as greater seed production), and can grow over a greater tidal range. Read more about why invasive Spartina is a problem.

By removing invasive Spartina and planting native vegetation, the Invasive Spartina Project restores healthy wetland habitat for Ridgway’s rails and other wetland species. Building high-tide refuge islands provides a place for marsh animals to retreat during king tides and storm surge. Learn more about our vision for a healthy San Francisco Bay.

Climate change factors into the Invasive Spartina Project in multiple ways, including sea level rise, carbon storage, and habitat resilency.

Sea level rise from climate change is impacting the Bay’s shoreline habitats and neighboring communities. Healthy marshes play an important role as green infrastructure and living shorelines, dampening high-energy waves that can be destructive. Addressing the spread of invasive Spartina is a critical part of keeping these marshes healthy.

Carbon storage is an important part of decreasing the effects of global warming, and research shows that healthy salt marshes can absorb large quantities of carbon dioxide from the atmosphere and store it (see NOAA’s Coastal Blue Carbon program).

Tidal marsh habitats and the plants and wildlife that live there are vulnerable to sea level rise and changing temperatures, precipitation, and levels of carbon dioxide. Invasive species are an additional stress on plants and wildlife; removing invasive species is an important step to build resiliency to climate change for the Bay’s native plants and animals.

For the majority of project sites, invasive Spartina plants are targeted by treatment teams using backpack sprayers to apply an herbicide approved for use in the sensitive estuarine habitat. For some larger sites, herbicide is applied using long hoses connected to an airboat or truck. At a few sites where it is possible, teams dig out or tarp over the invasive Spartina.

Treatment teams use targeted application of herbicide because it is the most effective way of controlling invasive Spartina and it causes the least amount of disturbance to sensitive marsh habitat. The treatment team uses an aquatic formulation of the herbicide imazapyr, which the U.S. Environmental Protection Agency considers a Category IV pesticide, determined as “practically non-toxic” to wildlife, including mammals, birds, fish, and aquatic invertebrates. This chemical formulation is designed to break down rapidly in water, has a low potential to bioaccumulate, is not carcinogenic, mutagenic, or neurotoxic, and is broken down by UV rays in sunlight. Regular water quality monitoring by the treatment team confirms that a 90% reduction of imazapyr is normally detected within the first week after application. Find the most recent water quality report on the Reports and Documents page.

The project completed a Programmatic Environmental Impact Report in 2003 and works under ongoing Biological Opinions from the U.S. Fish and Wildlife Service to ensure the protection of endangered species.

The project is managed by the California State Coastal Conservancy, the nonprofit California Invasive Plant Council, and the U.S. Fish and Wildlife Service, in collaboration with more than 150 partners around the Bay. Partners include cities, counties, local, state and federal agencies, water districts, mosquito abatement districts, researchers, many private landowners, and expert contractors who accomplish work in the field.

The project is funded by grants from local, state and federal agencies who are committed to protecting San Francisco Bay’s salt marshes.

Because invasive Spartina grows in relatively inaccessible intertidal sites with endangered species, only professional restoration workers are able to participate in the work directly. However, there are volunteer opportunities to remove other invasive plants that harm the Bay’s wetlands. Please look for volunteer organizations associated with local or regional parks or land management agencies to find opportunities in your area.