Over time, we had various opportunities to study viral disinfection of urban wastewater effluents; association of viruses with wastewater solids was considered (Cliver 1975 ). An early project used a mixture of two animal viruses and two bacteriophages to determine how each was inactivated by chlorine dioxide (Olivieri et al. 1983 ). We worked with Milwaukee, Wisconsin on disinfection of its effluents for discharge to Lake Michigan (Warriner et al. 1985) . We helped the Madison (Wisconsin) Metropolitan Sanitary District with a pilot study to show that UV would inactivate viruses in their treated effluent (unpublished) and later worked with them on seasonal antiviral disinfection of their effluent when the full system was in place (Buyong et al. 1993) .