2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 3
Presentation Time: 2:20 PM


FOGG, Graham E., Land, Air and Water Resources Department, Univ California, 1 Shields Ave, Davis, CA 95616-5270, gefogg@ucdavis.edu

Most groundwater that is used for public drinking water supply is older than ~50 yrs, but in North America most contaminant sources are younger than ~50 yrs. This, together with short-term monitoring data and modeling analyses suggest that groundwater quality in many basins may be on a long (decades to centuries), difficult to measure decline. The modeling analyses indicate that natural mixing phenomena due to heterogeneity and transient conditions tend to produce very large ranges in groundwater ages within individual water samples, whether obtained from a long screened interval or from a point in the aquifer system. This in turn suggests that recent data hinting at declining groundwater quality may merely represent the early phases of very long-term trends. In other words, if regional groundwater quality in a typical basin is indeed worsening, one might anticipate that the trend will be very gradual, potentially extending decades to a century or more, and possibly irreversible during that time. The above characteristics of regional groundwater quality change are reminiscent of the phenomenon of “creeping normalcy,” which was used by Diamond [2004] in explaining how some past civilizations have destroyed ecosystems upon which they depended, without ever foreseeing the problems in time to change course. Despite the seriousness of the groundwater quality sustainability issue, the needed monitoring and research have barely even begun. Few monitoring studies last more than a decade, and basin-scale, long-term groundwater quality modeling analysis is rarely done. Moreover, the foundation of research and methods needed to conduct such analysis needs immediate attention. A possible research agenda will be discussed.