Figure 2. Distribution of tracer-based piston-flow ages in groundwater samples from selected Land-Use Study and Major-Aquifer Study sites. Tracer-based piston-flow ages interpreted in this report (table 1) and previously interpreted (table F1, appendix F) are combined in this figure. Results that were censored with a “<,” “≤,” “>,” “≥,” or specifically were commented on in table F1 as likely affected by degradation [selected networks in the Allegheny-Monongahela River Basin (ALMN) Study Unit and Kanawha-New River Basin (KANA) Study Unit] are not shown. Tracer-based piston-flow ages of samples from age-dated wells likely do not represent the tracer-based piston-flow ages of samples from wells that were not dated.

First posted January 27, 2011