The District is currently assisting the California Coastal
Conservancy on the
San Francisco Estuary Invasive Spartina Project.
This project seeks to eradicate an invasive species of cordgrass
that threatens native habitats throughout the San Francisco Bay.
The US Fish and Wildlife, California Dept of Fish and Game, Bay
Area Regional Water Quality Control Board, Environmental
Protection Agency, Baykeeper, University of California, Sierra
Club, and Audubon Society participated in developing the
environmental review documents to eradicate invasive
The spread of non-native cordgrass has been a concern in tidal
areas of San Francisco Bay since the early 1970s. Invasive
Spartina spreads further onto pickleweed marshes and into tidal
mudflats in comparison to native cordgrass. Their spread reduces
essential habitats used by migratory birds and other endangered
species. Stalks of invasive Spartina are also taller and thicker
than the native cordgrass. Furthermore, their growth and spread
has begun to clog local marinas and flood control channels.
Without eradication efforts to control its spread, San Francisco
Bay is at risk of being dominated by this weed within 20 years.
The District controls Invasive Spartina along the shores of San
Francisco Bay with Imazapyr, an herbicide. This material
interferes with the function of an enzyme found only in plants
and therefore has no effect on animals, fish, or birds. The
material is applied directly to the leaves of the plant during
low tide. This material rapidly degrades via photolysis and
dissipates from water within several days and has no impact on
water quality. This material has been approved for application to
tidal wetlands by the Environmental Protection Agency.