Delta Invasive Species

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Invasive Animal Species in the Delta

The Sacramento-San Joaquin Delta is one of the world’s most invaded estuaries, with at least 185 non-native species already here and more likely to arrive in the future.

Below is information on some of the invasive species currently in the Delta and Suisun Marsh, species to watch out for, how to report invasive species, and additional resources.

Species of Concern

Invasive species of concern currently in the Delta and Suisun Marsh.

Animals

An American bullfrog in a person's hand. Image by Kerwin Russell, Riverside-Corona Resource Conservation District.

American bullfrog (Lithobates catesbeianus)

Photo by Kerwin Russell, Riverside-Corona Resource Conservation District

Close-up of a single golden clam. Image by Noel M. Burkhead, U.S. Geological Survey.

Golden clam
(Corbicula fluminea)

Photo by USGS

Image of a nutria's head, showing its white whiskers and orange teeth. Image by California Department of Fish and Wildlife.

Nutria
(Myocastor coypus)

Photo by CDFW

A gray wild cat on the run leaping and looking intensely forward. Adobe stock image.

Feral cat
(Felis catus)

Photo by alan1951/Adobe Stock

Close-up of a cluster of golden mussels being held in a gloved hand. Image by California Department of Water Resources.

Golden mussel
(Limnoperna fortunei)

Photo by DWR

A red-eared slider stretched out on a rock with a waterway in the background. Image by California Department of Fish and Wildlife.

Red-eared slider (Trachemys scripta elegans)

Photo by CDFW

A dark-colored feral pig in a field. Image by California Department of Fish and Game.

Feral pig
(Sus scrofa)

Photo by CDFW

Many tan-colored New Zealand mudsnails (Potamopyrgus antipodarum) shown with a dime for size reference. Photo by U.S. Geological Survey.

New Zealand mudsnail (Potamopyrgus antipodarum)

Photo by USGS

A red swamp crayfish on a rock. Image by U.S. Geological Survey.

Red swamp crayfish (Procambarus clarkii)

Photo by USGS

Plants

The white flower and green leaves of an alligatorweed (Alternathera philoxeroides) plant. Photo by National Plant Data Center, Baton Rouge, LA.

Alligatorweed (Alternathera philoxeroides)

Photo by National Plant Data Center, Baton Rouge, LA

Curlyleaf pondweed (Potamogeton crispis) plants in the water. Photo by Christian Fischer.

Curlyleaf pondweed
(Potamogeton crispis)

Photo by Christian Fischer

Purple loosestrife (Lythrum salicaria) plants with purple flowers and green leaves. Photo by Liz West

Purple loosestrife
(Lythrum salicaria)

Photo by Liz West

Purple water hyacinth (Eichhornia crassipes) flowers with yellow and blue markings and green leaves growing in the water. Photo by Wouter Hagens.

Water hyacinth
(Eichhornia crassipes)

Photo by Wouter Hagens

A section of the Brazilian egeria (Egeria densa) plant. Photo by Lara Gudmundsdottir.

Brazilian egeria
(Egeria densa)

Photo by Lara Gudmundsdottir

Eurasian watermilfoil (Myriophyllum spicatum) in the water. Photo by Fungus Guy.

Eurasian watermilfoil
(Myriophyllum spicatum)

Photo by Fungus Guy

White flowers and green leaves of the perennial pepperweed (Lepidium latifolium) plant. Photo by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org.

Perennial pepperweed (Lepidium latifolium)

Photo by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

The flower and leaves of a water primrose plant (Ludwigia spp.). Photo by Bouba.

Water primrose
(Ludwigia  spp.)

Photo by Bouba

Brown, fluffy seedheads and green leaves of the nonnative common reed (Phragmites australis subsp. australis) plant. Photos by Erlend Bjortvedt and U.S. Geological Survey.

Common reed
(Phragmites australis subsp. australis)

Photos by Erlend Bjortvedt and USGS

Giant reed (Arundo donax) plants growing in the Sacramento-San Joaquin Delta.

Giant reed
(Arundo donax)

Ribbon weed (Vallisneria australis). Photo by Nick Rasmussen, California Department of Water Resources.

Ribbon weed
(Vallisneria australis)

Photo by Nick Rasmussen, DWR

South American spongeplant (Limnobium laevigatum) in the water. Photo by Cardex.

South American spongeplant
(Limnobium laevigatum)

Photo by Cardex

Species Watch List

Invasive species of concern that have been reported near the Delta or Suisun Marsh.

A northern watersnake (Nerodia sipedon) with brown and tan stripes in the grass next to a rock. Photo by Patrick Coin.

Northern watersnake (Nerodia sipedon)

Photo by Patrick Coin

Grouping of bright-green water lettuce (Pistia stratiotes). Photo Troy Evans, Great Smoky Mountains National Park, Bugwood.org.

Water lettuce
(Pistia stratiotes)

Photo Troy Evans, Great Smoky Mountains National Park, Bugwood.org

A southern watersnake (Nerodia fasciata) with tan, brown, and red-striped skin in the grass. Photo by CDFW.

Southern watersnake (Nerodia fasciata)

Photo by CDFW

A single yellow floating-heart (Nymphoides peltata) surrounded by green vegetation. Photo by Lyn Gettys, University of Florida, Institute of Food and Agricultural Sciences.

Yellow floating-heart (Nymphoides peltata)

Photo by Lyn Gettys, University of Florida, Institute of Food and Agricultural Sciences

Five dark brown/tan-striped and five light brown/tan-striped Quagga Mussels (Dreissena rostriformis bugensis) shown next to a dime in a person's hand for size reference. Photo by CDFW.

Quagga mussel (Dreissena rostriformis bugensis)

Photo by CDFW

A Zebra mussel (Dreissena polymorpha) with brown, tan, and cream-colored stripes.

Zebra mussel
(Dreissena polymorpha)

Report Invasive Species

Report an Invasive Species Sighting to the California Department of Fish and Wildlife (CDFW)

Report a Pest to the California Department of Food and Agriculture (CDFA)

Resources

Information from CDFW

Information from the California State Parks Division of Boating and Waterways

Golden Mussels’ Threat to California Agriculture