Quagga/Zebra Mussel Sighting and Distribution in Western US 2007-2009

  Looks like Nevada and San Diego area have been hit the worst--interesting that its the warmer places that seem to get hit hardest--but that may have more to do with the number of non-fishing boaters and warm water sports.
http://nas.er.usgs.gov/taxgroup/mollusks/zebramussel/maps/southwest_quagga.pdf