Lead release to standing water in October was an estimated 65% of that in February (p <<0.001, n = 134, signed-rank test). Copper release exhibited a similar trend: its concentration in standing water in October was an estimated 67% of that in February (p <<0.001, n = 134). These data represent total concentrations, but lead and copper concentrations in 0.45 µm filtrate were an estimated 75 and 89% of the corresponding total concentrations in paired aliquots representing 360 samples collected as profiles from residences with full or partial lead service lines (as described in Trueman et al., Figure ). This suggests that lead and copper were largely present in the system in forms smaller than 0.45 µm.