Document ID: EPA-HQ-OW-2017-0303-0027
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2018-02-23T05:00Z

From: Fleck, Diane 
Sent: Monday, January 22, 2018 10:08 AM
To: 'John Kenny' <kennyjd@gmail.com>
Subject: RE: Proposed EPA Withdrawal of Certain Federal Criteria for California

Hello Mr. Kenny,
Thank you for your continuing interest.  Since MCLs and ambient human health water quality criteria are derived using different equations and assumptions, one would need to look at the different factors that go into the derivation of each to determine whether they may have a different risk to human health under similar conditions.  Here is the link to explain how EPA derives recommended human health ambient water quality criteria for Clean Water Act purposes:  https://www.epa.gov/wqc/fact-sheet-methodology-deriving-ambient-water-quality-criteria-protection-human-health-revised.  Please see EPA's webpage regarding the Safe Drinking Water Act and MCLs at:  https://www.epa.gov/dwregdev/how-epa-regulates-drinking-water-contaminants.

In answer to your question concerning whether EPA takes cost and feasibility into consideration, the Clean Water Act requires that ambient water quality criteria be based on values that protect designated waterbody uses concerning human health and aquatic life, and does not allow economics (cost) to factor into the calculation.  This means that only scientific considerations can be taken into account when determining what water quality conditions are consistent with meeting a given designated use. Economic and social impacts are not allowed to be considered when developing criteria.  For further information and explanation, please EPA's introduction to the Clean Water Act module (Watershed Academy Web) at: https://cfpub.epa.gov/watertrain/pdf/modules/IntrotoCWA.pdf. Page 12 discusses this specific issue concerning economics.

Since we are currently taking public comment on our proposed action, if you have additional comments or questions, please submit them to us through the public Docket for this action at the Regulations.gov website: https://www.regulations.gov/docket?D=EPA-HQ-OW-2017-0303 .  The deadline to submit comment is February 9, 2018. 

For more detailed information on this action, please see EPA's website:  https://www.epa.gov/wqs-tech/withdrawal-certain-federal-criteria-california . 

Thank you again for your interest.
Diane Fleck

Diane E. Fleck, P.E., Esq.
U.S. EPA Region 9 WTR-2-1
75 Hawthorne Street
San Francisco, CA 94105
P: 415 972-3527 Tuesday/Thursday
P: 408 243-9835 Monday/Wednesday
Fax: 415 947-3537

From: John Kenny [mailto:kennyjd@gmail.com] 
Sent: Thursday, January 18, 2018 12:52 PM
To: Fleck, Diane <Fleck.Diane@epa.gov>
Subject: Re: Proposed EPA Withdrawal of Certain Federal Criteria for California

Hello Diane, 
Thank you for the helpful response. 
Since the Safe Drinking Water Act TTHM MCL takes costs and feasibility into consideration, does that mean that the TTHM MCL lead to a risk greater than 10^-6 lifetime risk? 
Good point that the Clean Water Act CTR DBCM and DCBM level also take into account exposure through fish consumption; however, since the DBCM and DCBM "organism only" limits are in the 30's and 40's ug/L, where as the "water & organism" limits are in the 0.4's and 0.5's ug/L, it's clear that the organism consumption contribution to "water and organisms" is negligible (about 1/100th). Do you know if different assumptions were made in the risk calculations (e.g., different endpoint data, different water intakes, etc.)? 
Lastly, why don't the Clean Water Act CTRs take cost and feasibility into consideration? It leads to an odd situation in California, where the wastewater of some communities is safer to drink, from a TTHM point of view (and expensive to treat), than their drinking water. 
Best, 
John

On Wed, Jan 17, 2018 at 3:00 PM, Fleck, Diane <Fleck.Diane@epa.gov> wrote:
Hello Mr. Kenny,
Thank you for your interest.  The method of determining MCLs under the Safe Drinking Water Act and the method used to calculate human health ambient water quality criteria under the Clean Water Act consider different factors.  These differences can sometimes result in quite different values.  Below are some bullets to consider:
 
 EPA's human health Clean Water Act section 304(a) criteria recommendations are designed to minimize the risk of adverse effects occurring to humans from chronic (i.e., lifetime) exposure to pollutants through the ingestion of drinking water and consumption of fish and shellfish obtained from ambient surface water, while also protecting against adverse effects that may reasonably be expected to occur as a result of elevated acute or short-term exposures. In contrast, the Safe Drinking Water Act (SDWA) controls the presence of contaminants in finished drinking water ("at-the-tap").
 Because exposure through the ingestion of drinking water and consumption of fish and shellfish are considered, the criteria are typically expressed as "water + organism" criteria.
 MCLs, on the other hand, are developed with consideration given to the costs and technological feasibility of reducing contaminant levels in water to meet those standards.  In addition, MCLs do not consider exposure pathways beyond drinking water, e.g., exposures via fish consumption.
 
In answer to your second question:  we are proposing to remove criteria for lead and the two trihalomethanes only for the waters (and associated uses) for which the State adopted site-specific objectives.  
 
I hope this information answers your questions.  If you have any additional questions, please do not hesitate to contact me.
 
Diane Fleck
 
Diane E. Fleck, P.E., Esq.
U.S. EPA Region 9 WTR-2-1
75 Hawthorne Street
San Francisco, CA 94105
P: 415 972-3527 Tuesday/Thursday
P: 408 243-9835 Monday/Wednesday
Fax: 415 947-3537
 
From: John Kenny [mailto:kennyjd@gmail.com] 
Sent: Friday, January 12, 2018 5:39 PM
To: Fleck, Diane <Fleck.Diane@epa.gov>
Subject: Proposed EPA Withdrawal of Certain Federal Criteria for California
 
Hi Diane, 
 
I don't understand why the CTR water & organisms DCBM and DCBM goals are so low (0.4 ug/L and 0.56 ug/L), compared to the drinking water TTHM MCLs (80 ug/L). Is it because the TTHM MCL is an MCL, which takes economics, etc. into account, whereas the CTR is more like a goal? They both are trying to achieve 10^-6 risk, I believe; do they make different assumptions? 
 
Also, why does this change only apply to certain water bodies and not others? 
 
Best, 
 
John