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TE News v.13--
Arsenic in groundwater; new proposed MCL

To: GS-W_NAWQA_97_PC,
    GS-W_NAWQA_91_PC,
    GS-W_NAWQA_94_PC
Cc: jszogors, rgilliom, stoner, cacouch,
    ahwelch, pcvanmet, rdeweese, dpkrabbe, sjryker, cory, dhelsel,
    tlmiller, wgwilber, bobwill, armbrust, mcyurewi, ijames, sylvest,
    GS-W_OWQ_wqspecs,
    WRD trace element interest gp:;,wlapham,fwilde,jdmartin,mueller,tschertz,jon,gcdelzer,bfconnor,
    pahamilt, egraffy
From:  Dennis R Helsel
Date:  05/30/00 04:41 PM
Subject: TE News v.13 Arsenic in groundwater; new proposed MCL

Trace Element Synthesis News v.13
Arsenic in Groundwater; new proposed MCL

1. New regulation
2. New publications
3. New wrinkle

Study-unit chiefs: Please see that your ground-water staff see this news note.

New regulation

Last week the USEPA released its proposal for a new MCL for arsenic in drinking water. The existing MCL was 50 ug/L; the proposed new standard is 5 ug/L, a ten-fold decrease. Arsenic is implicated in causing several cancers, and this concern was not recognized when the previous standard was set decades ago. As we often compare water-quality data to a standard, comparisons for arsenic should be made to the proposed 5 ug/L standard as well as to the existing MCL until it is officially replaced in 2001. USEPA will adopt the new standard in early 2001 following a comment period. It is not certain they will settle on 5 -- there are interests pulling both up and down. But the new standard will not be anywhere near 50, so comparing only to that value is no longer appropriate.

New publications

USGS reviewed all of our arsenic data in groundwater from NWIS as part of the review process for setting this standard. The results are available on the TE Synthesis web page: http://water.usgs.gov/nawqa/trace/arsenic

Found there is a WRI by Focazio and others which provides a detailed look, as well as just-completed fact sheet by Welch and others summarizing the results for our nontechnical audience. Our findings were used by USEPA as they considered what level at which to set the new standard. The maps from the fact sheet have been picked up by many news outlets. Also found there are links to other information on arsenic in drinking water, including USEPA's web site and the report of the National Academy of Sciences.

Paper copies of the fact sheet will be mailed to each District office during the week of June 5th. Additional copies are being sent to Districts with NAWQA projects rather than doing a separate mailing to study units. So look for your copies to arrive in the District office soon.

New wrinkle

Sarah Ryker and Alan Welch have added new data since the fact sheet -- most from State agency sources, with a little of the 1997 study-unit data. A draft of their newest map, which changes frequently, is found at http://water.usgs.gov/nawqa-only/trace/summary/as_hex_30km_mean.gif

You can see the valuable addition of data from Minnesota, Texas, and parts of New England, which previously were mostly blank. If you know of data on arsenic in source (not finished) waters in ground eater of your state, available electronically and analyzed by methods like hydride generation or ICP (reporting limits near 1 ug/L), please let Sarah Ryker (sjryker) know. We would like to fill in some more of the gaps in this map.

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 much info for study units: http://water.usgs.gov/nawqa-only/trace/ including the previous TE news blurbs:

v.1   Trace Element Synthesis Staffing and plans   2/10/99
v.2   Changes to TE lab methods for bed sediments  2/19/99
v.3   Well Selection for Subunit Surveys           2/26/99
v.4   Mercury in Streambed Sediments               3/04/99
v.5   Radium in Ground Water                       4/08/99
v.6   Elements in Sch 2703                         6/14/99
v.7   TEs in stream seds across US                 8/18/99
v.8   TE Synthesis: Live and Online               10/04/99
v.9   New Radon Standards proposed by US EPA      10/22/99
v.10  Info for '94 Study-Unit Summary Reports     11/24/99
v.11  TE Schedule change to 2710                   2/07/00
v.12  Results of TE Blanks from 91 Study Units     2/09/00

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