New Zealand Mud Snails
On October 30, 2003, biologist Ken Davis incidentally discovered a population of New Zealand Mud Snails (NZMS), Potamopyrgus antipodarum, in Putah Creek while conducting surveys to catalogue the native aquatic invertebrates of the system. The Putah Creek discovery was the first appearance of the organism west of the Sierra Nevada’s. Since this initial finding, NZMS have been found in the Mokelumne, Calaveras, and Napa Rivers.
Since the initial discovery of NZMS in the Putah Creek inter-dam reach, between Monticello and the Putah Diversion Dams, the snails have spread approximately 6 miles downstream from the epicenter at Fishing Access #3 after sustained high flood flows during the 2003-2004 winter. It is very likely that the limit of infestation has moved farther downstream due to flood flows in Putah Creek during the winter/spring of 2006.
The infested reach includes the intake to the Putah South Canal ( PSC). The PSC is a concrete lined water delivery canal owned by the U.S. Bureau of Reclamation and operated by the Solano County Water Agency (SCWA). The first colonization of the PSC by NZMS was discovered within the first 1.5 miles on March 21, 2005. Further delineation of the geographic limit of spread in the PSC is currently being conducted. SCWA is also conducting chemical treatments in the laboratory, through the California Department of Fish and Game's Pesticide Investigations Unit to determine if there are ways to control NZMS in the PSC.
Mollusks found in Putah Creek
Images and Species Descriptions Provided by Ken Davis of Wildlife Survey and Photo Service
SCWA White Paper-NZMS in Putah South Canal 
Emergency Delineation of NZMS Population in Putah Creek
Putah Creek NZMS Monitoring Project
Survey Methods Used For NZMS in Putah Creek
Montana State University-NZMS in the Western USA
Bibliography of Known NZMS Literature (not an exhaustive list)
California Department of Fish and Game News Releases:
California Department and Fish and Game Seeks Assistance in Slowing Spread of NZMS
U.S. Fish and Wildlife Service Invasive Species Program
U.S. Fish and Wildlife Service White Paper-Select Research Findings on the NZMS
U.S Fish Wildlife Service White Paper-Don't be a NZMS Vector
