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TE News v.15--
New arsenic MCL at 10 ug/L

To: nawqa 91pc, nawqa 94pc, nawqa 97pc, nawqa 91pc, wqspecs
Cc: nawqa nst, ahwelch, pcvanmet, rdeweese, dpkrabbe, sjryker, cory,
    mkoterba, nawqa nlt, pahamilt, egraffy, akwill
From:  Dennis R Helsel
Date:  01/19/01 01:53 PM
Subject: New arsenic MCL at 10 ug/L

Trace Element Synthesis News v.15
New arsenic MCL at 10 ug/L

USEPA has completed its arsenic rulemaking process, and has settled on 10 ug/L as the new MCL for drinking water. This is the value that should be used as the criterion/standard for arsenic in drinking water in USGS reports from this time forward. You may remember that 5 ug/L was previously under consideration (see TE News v. 13). That was increased to 10 ug/L, the World Health Organization's recommended value, in the final stages of the rulemaking process. You will find a Washington Post article covering the new arsenic standard on our Trace Element external page ("In the News"), and a link to USEPA's information on the Final Rule on our arsenic page:
http://water.usgs.gov/nawqa/trace/arsenic/

The USEPA fact sheet on the new rule can be found at
http://www.epa.gov/safewater/ars/ars_rule_factsheet.html

As expected, the decrease from 50 to 10 will cost water utilities a great deal of money in some locations, and they are looking for help from State and Federal government sources. Environmental groups are not pleased with the increase from 5 to 10, and will likely sue USEPA. So the controversy will continue, but the new standard is now the law and is not likely to change over the next few years.

A guide to locations where arsenic is higher than 10 can be found

1. in county format on our arsenic page http://water.usgs.gov/nawqa/trace/arsenic/
2. in a more consistent spatial format in ongoing (DRAFT) work by Sarah Ryker at: http://water.usgs.gov/nawqa-only/trace/summary/Arsenic_GW_US.jpeg

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 all the TE News. The previous four were:

 v.11  TE Schedule change to 2710                   2/07/00
 v.12  Results of TE Blanks from 91 Study Units     2/09/00
 v.13  Arsenic in Groundwater; new proposed MCL     5/30/00
 v.14  Changes in radchem data reporting            9/29/00

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