Potential of Cryptosporidium parvum Oocysts at the Russian

Carboxylated microspheres were employed as surrogates to as-sess the transport potential of Cryptosporidium parvum oocysts dur-ing forced- and natural-gradient tests conducted in July and Octo-ber 2004. The tests involved poorly-sorted, near-surface sediments where groundwater is pumped from an alluvial aquifer under-lying the Russian River, Sonoma County, CA. In an off channel infiltration basin and within the river, a mixture (2-, 3-, and 5-μm diameters) of fluorescently-labeled carboxylated microspheres and bromide tracers were used in two injection and recovery tests to assess sediment removal efficiency for the microspheres. Bottom sediments varied considerably in their filtration efficiency for Cryptosporidium