News from NAS Alerts today that Quagga mussels (Dreissena rostriformis bugensis) have again been found past the 100th Meridian Line, this time in California. The mussels were discovered in Lake Havasu, one site in Riverside, and a single specimen in San Bernadino. If you check this USGS map you'll see that the California sites are located along the Colorado River, just one USGS hydrologic unit away from the Nevada infestation uncovered a couple of weeks ago. Yikes.
Interested readers may want to check out this report from the L.A. Times.