Stein says there was samplingwell before their "Payoff Mix, " although it existed in a different form namely, the popular Flying Saucer records, which were collages created by Bill Buchanan and Dickie Goodman.
Since data from some homes showed elevated contaminant levels and several residents expressed concern, EPA determined that wellsampling was necessary to gather additional data and evaluate whether those residents had access to safe drinking water.
As students, you should keep in mind that all these numbers are estimates based on samples, which are thus subject to sampling error (as well as other types of errors).