Introduction

The WIPP EM studies of ground water focus on the major drinking water supplies used by communities in the WIPP region because these are often perceived by the public as a potential route for contaminants to reach humans. However, studies of the hydrogeology of the region suggest (1) that the risk is low for contaminants from the WIPP to reach the various regional underground aquifers that are used as sources of drinking water, and (2) the movement of contaminants into these aquifers, if it occurred, would be extremely slow (DOE, 1997, Waste Isolation Pilot Plant Disposal Phase Final Supplemental Environmental Impact Statement, DOE/EIS-0026-S-2). Five community supplies of drinking water (representing three major regional aquifers) are included in routine sampling, including Carlsbad, Loving/Malaga, Otis, Hobbs, and a secondary source for Carlsbad. One private water well (representing a fourth aquifer) that is located within ten miles of the WIPP is also sampled because it is the only private well in close proximity to the WIPP that is known to have been used for human consumption in recent years, and because it draws from the aquifer considered most likely to be contaminated by releases from the WIPP into ground water, (DOE, 1990, Final Supplemental Environmental Impact Statement, DOE/EIS-0026-FS).

Detailed summaries of the sampling design and analytical procedures for the WIPP EM drinking water studies were presented in the CEMRC 1998, 1999 and 2000 reports. Briefly, samples for municipal systems are drawn from the primary reservoir vessels downstream of the well sources, which are more representative of the overall water supply than samples from individual wells. Likewise, for municipal supplies, samples are not taken from individual user taps because of the potential contamination introduced via the residential segments of the system, which would have no demonstrable relationship to contaminants from the WIPP. Recent data presented herein are from six samples collected during April-May 2001. Detailed data summaries are provided in each year’s annual report, which is issued each February, and encompasses results from sampling and analyses completed through September of the previous year.