Figure 2: Schematic representation of surveillance sites along the sewage system in central Israel Sewage in the Shaf Dan catchment area in central Israel flows north by gravitation to the Reading pumping plant. The sewage is pumped upwards at the Reading Station as well as at a point stream so that it can then flow south by gravitation to the Shaf Dan Waste Water Treatment Plant. Sewage is collected at the mouth of the Shaf Dan Treatment Plant by an inline automatic composite sampler. The direction of the flow is indicagted by the black arrows. Upstream samples are collected by portable automatic composite samplers lowered into the system at Reading, the mouth of Kav B and along the Ayalon trunk line at sites indicated by the circles. Samples are treated and analyzed for the pres- ence of polio and non-polio enteroviruses as described in Materials. The collec- tion sites in the figure correspond to the sites listed in Table 1. The Ayalon site in Figure 3 is located at the mouth of the Ayalon Line C just before it enters the Reading Pumping Station.