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Trace Element Synthesis News v.19
Arsenic-- New MCL; New national maps

To:  nawqa 01pc, nawqa 91pc,nawqa 94pc, nawqa 97pc,
     nawqa 01gws, nawqa 91gws, nawqa 94gws, nawqa 97gws,
     OWQ wqspecs, nawqa EPA liaisons, EPA liaisons, GS-W DC
Cc:  GS-W NAWQA nst, GS-W NAWQA nlt, GS-W NAWQA ntt,
     ahwelch, pcvanmet, rdeweese, dpkrabbe, sjryker, mfocazio, cory,
     mkoterba, mbrigham, gpatter, pahamilt, GS-W NAWQA Data Synthesis,
     egraffy, ralex, rsmith1
From: Sarah J Ryker
Date: 11/05/01 11:28 AM
Subject: Arsenic-- New MCL; New national maps

New MCL

On October 31st, 2001, the USEPA announced that they will implement the new maximum contaminant level for arsenic in drinking water at 10 ug/L. Public water systems have until January 2006 to meet this new standard. See the EPA arsenic website:
http://www.epa.gov/safewater/arsenic.html

New national maps

The November 2001 issue of Geotimes features three new national maps of arsenic in ground water. We don't expect the new maps to contain any great surprises, but wanted to give you a "heads up" just in case. These maps update what was published in May 2000 ( http://water.usgs.gov/nawqa/trace/pubs/fs-063-00/ ) and discuss issues in interpreting the maps. The article will also appear on the Geotimes website ( http://www.geotimes.org/current/ ) as a "Geosciences and Human Health" feature article during November. The reference is:
 Ryker, S.J., Nov. 2001, Mapping arsenic in ground water-- A real need, but a hard problem: Geotimes v.46 no.11, p.34-36.

The primary change in the maps is the spatial coverage. The May 2000 maps showed USGS arsenic data from 19,000 wells and springs. The new maps include comparable data from several state agencies, for a total of 31,000 wells and springs. We have contacted our technical counterparts at each contributing agency about the upcoming article, and the Geotimes editors have agreed to list our data sources if space permits. At the very least, Geotimes will put links to the agencies in the on-line version of the article. The data sources for the new maps are:

• Maine Department of Health
• Massachusetts Department of Environmental Protection
• Minnesota Pollution Control Agency
• New Hampshire Department of Environmental Services
• Rhode Island Department of Health
• Texas Water Development Board
• USGS National Water Information System
• Vermont Department of Environmental Conservation
• Wisconsin Department of Natural Resources

The focus of the article is a discussion of the limitations of these national maps. There's been a lot of over-interpretation of what we published last year, so we're trying to do some basic education along the lines of:

1. This is not a "risk map" of where one might expect to see health effects from arsenic in drinking water
2. A map of arsenic in ground water doesn't give a complete picture of drinking water
3. National maps like this can provide an interesting overview but are too general to be used for local interpretations.

The NAWQA Trace Elements Synthesis public website may help you answer any inquiries:

Arsenic in ground water of the U.S.
http://water.usgs.gov/nawqa/trace/arsenic/

Contact Sarah Ryker, ground-water lead for NAWQA Trace Elements Synthesis (sjryker@usgs.gov, 303-236-2101 ext. 224), for additional information.

Visit the TE external page at: http://water.usgs.gov/nawqa/trace/ for up-to-date info on regulations, publications, etc.

The TE synthesis internal page has additional info for study units: http://water.usgs.gov/nawqa-only/trace/
including all the TE News. The previous four were:

v.18   Comparison of TEs in bed sediments to Canadian Guidelines   (4/27/01)
v.17   TE sampling in the 01 Study Units   (4/2/01)
v.16   New methylmercury criteria   (2/5/01)
v.15   New arsenic MCL at 10 ug/L   (1/19/01)

Trace Elements National Synthesis internal homepage - Archive of 'TE News'
National Analysis of Trace Elements (public)
National Water-Quality Assessment (NAWQA) (public)