New Zealand Mud Snails

Montana Natural Heritage Program photo

Montana Natural Heritage Program photo

“Preliminary studies indicate that in areas where they have become densely populated they are becoming the dominant invertebrate via displacement and competitive interactions. Large populations may consume up to half of the available food in a stream, starving out insects essential to trout and salmon. A recent study by the U.S. Bureau of Land Management and the Utah State University (Vinson and Baker, 2008) linked these invasive snails to poor condition of trout due to lack of a regular food source and that the snails did not provide sufficient nutritional value when consumed.”
— Washington Dept. of Fish & Wildlife

New Zealand Mud Snail 

As of early 2014, there are no known locations of New Zealand mud snails in the Upper Sacramento or McCloud Rivers.  But this invasive snail is now known to occur at many locations used by fishermen  in N. California.  Human recreational activities are clearly an important factor in the spread of this species.  Below is a list of locations as of summer 2013.  

  • Bridge Bay Marina, Shasta Lake
  • Clear Creek near Redding
  • Sacramento River between Redding and Anderson
  • North Street Bridge, Anderson
  • Rooster’s Landing, Balls Ferry
  • Barge Hole, Sacramento River below Balls Ferry
  • Bend Bridge
  • Red Bluff City Park Stone Lagoon and Big Lagoon, Humboldt County
  • Redwood Creek
  • Russian River at Healdsburg
  • Russian River near Forestville
  • Garcia River at Windy Hollow Rd
  • American River in Sacramento – 8 locations from Nimbus to Discovery Park
  • Putah Creek – 2 locations below Lk. Berryessa
  • Napa River – Yountville Preserve and in Napa
  • Mokelumne River near Clements
  • Calaveras River in Bellota and near Jenny Lind
  • Stanislaus River – Goodwin Dam to Ripon
  • Merced River north of Merced Antioch - Canal below municipal reservoir 
  • Vallecitos Creek in Sunol
  • Alameda Creek in Fremont
  • Baxter Creek in Richmond 
N. Cal., S. Ore., Idaho Locations as of August, 2012

N. Cal., S. Ore., Idaho Locations as of August, 2012

FISHERMEN AND BOATERS --- are YOU a threat to the watershed???

New Zealand Mud Snail infestations in California and the Western U.S. are clearly associated with recreational access points. 

PLEASE HELP BY CLEANING YOUR WADING GEAR AND YOUR BOAT (INCLUDING FLOAT TUBES AND RAFTS) WHEN MOVING BETWEEN LAKES AND RIVERS THROUGHOUT CALIFORNIA AND THE WEST!!!