Large-scale aquifer tests for groundwater development and contaminant transport projects can meaningfully reduce uncertainty of hydraulic-property estimates. Environmental fluctuations in groundwater levels from barometric changes, tidal forcing, or surface-water stage changes can hinder or enhance hydraulic characterization. Environmental fluctuations obscure drawdowns during pumping-aquifer tests and are best eliminated to expand the investigated volume. Hydraulic properties also can be estimated by interpreting the ubiquitous signals that environmental fluctuations provide.