Copper concentrations (ppb) at two background wells and one compliance well (six measures at each well).
EPA.09.Ex.16.4.copper.dfA data frame with 18 observations on the following 4 variables.
Montha factor indicating the month of collection
Wella factor indicating the well number
Well.typea factor indicating the well type (background vs. compliance)
Copper.ppba numeric vector of copper concentrations (ppb)