U.S. ENVIRONMENTAL PROTECTION AGENCY – REGION 10

Technical Support 

Document

for Action on the State of Oregon’s New and 

Revised Human Health Water Quality Criteria for 

Toxics and Associated Implementation Provisions 

Submitted July 12 and 21, 2011

October 17, 2011
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

2 

Contents

I. INTRODUCTION .................................................................................................................. 4

II. ORGANIZATION OF DOCUMENT .................................................................................... 7

III. BACKGROUND ................................................................................................................ 8

A. ODEQ’S JULY 12 AND JULY 21, 2011 SUBMITTALS............................................... 12

IV. ODEQ’S NEW AND REVISED HUMAN HEALTH CRITERIA .................................. 14

A. EPA REVIEW OF OREGON’S HUMAN HEALTH CRITERIA REVISIONS ............. 14

1. Human Health Criteria Applicability to Oregon’s Waters ........................................... 14

2. Non-Carcinogens: Criteria Methodology and Input Variables Used by Oregon .......... 18

a) Reference Done (RfD) .............................................................................................. 19

b) Body Weight (BW) ................................................................................................... 20

c) Drinking Water Intake Rate (DI) .............................................................................. 20

d) Bioaccumulation/Bioconcentration Factor (BAF/BCF) ........................................... 20

e) Fish Consumption Rate (FC) .................................................................................... 22

f) Relative Source Contribution (RSC) ........................................................................ 23

3. Carcinogens: Criteria Methodology and Input Variables Used by Oregon ................. 25

a) Body Weight, Drinking Water Intake Rate, Bioaccumulation/Bioconcentration 

Factor and Fish Consumption Rate ................................................................................... 26

b) Cancer Slope Factor .................................................................................................. 27

c) Carcinogenic Risk Level ........................................................................................... 27

4. EPA Review of Input Variables for All New and Revised Human Health Criteria 

except Methylmercury and Arsenic ...................................................................................... 28

B. EPA ACTION ON ODEQ’S NEW HUMAN HEALTH CRITERIA .............................. 28

C. EPA ACTION ON ODEQ’S REVISED HUMAN HEALTH CRITERIA ...................... 30

D. METHYLMERCURY CRITERION ................................................................................ 33

1. Methylmercury: Criteria Methodology and Input Variables Used by Oregon ............. 33

a) Relative Source Contribution (RSC) for Methylmercury ......................................... 36

2. New human health criteria for methylmercury ............................................................. 37

3. EPA Action and Rationale Regarding Oregon’s Methylmercury Criterion ................. 38

E. INORGANIC ARSENIC CRITERIA............................................................................... 39

1. Background ................................................................................................................... 39

2. Numeric Criteria Revisions........................................................................................... 41

a) Freshwater Criteria.................................................................................................... 42

b) Saltwater Criteria ...................................................................................................... 47
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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c) EPA Review of Oregon’s Revised Arsenic Criteria ................................................. 50

(1) FRESHWATER CRITERIA ............................................................................... 50

(2) SALTWATER CRITERIA ................................................................................. 53

(3) GENERAL CONSIDERATIONS ...................................................................... 54

3. EPA Action and Rationale Regarding Oregon’s Arsenic Criteria ................................ 55

F. NEW, REVISED AND WITHDRAWN FOOTNOTES .................................................. 58

1. New Footnotes .............................................................................................................. 58

2. Revised Footnotes ......................................................................................................... 60

3. Withdrawn Footnotes .................................................................................................... 62

G. WITHDRAWN HUMAN HEALTH CRITERIA WHICH WERE REPLACED BY 

MORE SPECIFIC CRITERIA ................................................................................................. 63

H. TABLE 40 HUMAN HEALTH CRITERIA SUMMARY .............................................. 66

V. NARRATIVE STATEMENT ............................................................................................... 68

VI. BACKGROUND POLLUTANT CRITERIA PROVISION ............................................ 70

A. BACKGROUND .............................................................................................................. 70

B. ODEQ’S JULY 21, 2011 SUBMITTAL .......................................................................... 73

C. EPA ACTION ON ODEQ’S NEW BACKGROUND POLLUTANT CRITERIA 

PROVISION ............................................................................................................................. 77

VII. VARIANCE PROVISION................................................................................................ 87

A. BACKGROUND .............................................................................................................. 87

B. ODEQ’S JULY 21, 2011 SUBMITTAL .......................................................................... 89

C. EPA ACTION ON ODEQ’S REVISED VARIANCE PROVISION............................... 93

VIII. BACTERIA....................................................................................................................... 99

IX. REVISED RULES REGARDING IMPLEMENTAIN FOR NONPOINT SOURCES . 100

A. STATEWIDE NARRATIVE CRITERIA ...................................................................... 100

B. OTHER IMPLEMENTATION OF WATER QUALITY .............................................. 101
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

4 

TECHNICAL SUPPORT DOCUMENT

For Action on the State of Oregon’s New and Revised Human 

Health Water Quality Criteria for Toxics and Associated 

Implementation Provisions

Submitted July 12 and 21, 2011

I. INTRODUCTION

In consideration of current information relative to fish consumption in Oregon, the Oregon 

Department of Environmental Quality (ODEQ) proposed revisions to Oregon’s water quality 

standards (WQS) located in Chapter 340, Division 41 of Oregon’s Administrative Rules (OAR 

340-041). ODEQ proposed new and revised human health water quality criteria for toxics and 

associated implementation provisions on December 21, 2010. ODEQ provided a formal public 

comment period on the proposed revisions and held nine public hearings. The public comment 

period extended from December 21, 2010 through March 21, 2011. 1,075 written comments 

were received and responded to by ODEQ. Revisions were adopted by the Oregon 

Environmental Quality Commission (EQC or Commission) on June 16, 2011, and filed with 

Oregon Secretary of State on July 13, 2011. Oregon’s submittal included a letter dated July 20, 

2011, from Larry Knudsen, Assistant Attorney General, certifying that the revisions were 

adopted in accordance with Oregon State law. In accordance with Section 303(c) of the Clean 

Water Act (CWA) ODEQ submitted these revisions to EPA for review and approval on July 21, 

2011. 

ODEQ revised their human health criteria for iron and manganese in a separate submittal dated 

January 18, 2011, which EPA approved on June 9, 2011. ODEQ also revised the human health 

criteria for arsenic in a separate submittal dated July 12, 2011, which EPA is now approving as 

part of this action. ODEQ accepted public comments on these revisions from August 25 to 

September 30, 2010, and held public hearings in Portland and Pendleton. ODEQ also conducted 

further public comment on the proposed rule, including revised proposed numeric criteria from 

February 1 to February 23, 2011. These revisions were adopted by the EQC on April 21, 2011 

and became effective under State law upon filing with the Oregon Secretary of State on June 30, 

2011. ODEQ submitted the revisions to the human health criteria for arsenic to EPA for review 

and approval on July 12, 2011. Oregon’s submittal included a letter dated July 11, 2011, from 

Larry Knudsen, Assistant Attorney General, certifying that the revisions were adopted in 

accordance with Oregon State law.

The June 16, 2011 rule package adopted by the EQC included revisions to the States’ Total 

Maximum Daily Load (TMDL) and National Pollutant Discharge Elimination System (NPDES) 

permitting regulations found in OAR 340-042 and 045. These are revisions to Oregon’s 

implementation rules and are not water quality standards. Accordingly, Oregon did not include 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

5 

them in the materials submitted for review under Section 303(c) of the CWA and EPA does not 

address them in today’s action. 

Revisions addressed in today’s decision can be divided into the general categories described 

below. 

1. New and revised human health criteria for carcinogens and non-carcinogens at OAR 

340-041-0033. 

ODEQ adopted new and revised human health criteria for 104 toxic pollutants (48 noncarcinogens and 56 carcinogens) based on a fish consumption rate of 175 grams per 

day. The criteria for these toxic pollutants are consistent with EPA’s 304(a) 

recommended criteria values1 and were derived using the methodology presented in 

EPA’s 2000 Methodology for Deriving Ambient Water Quality Criteria for the 

Protection of Human Health2 and EPA’s 2001 Methylmercury guidance.

3

 The new and 

revised human health criteria for toxic pollutants are contained in Table 40. 

Additional revisions related to the human health criteria include: 

• The removal of 13 pollutants consistent with EPA’s removal of 304(a) 

recommended criteria values for these same pollutants. Most of these recommended 

criteria were withdrawn since EPA developed individual criteria for the most toxic 

of chemicals in the family of chemicals represented by those 13 pollutants. 

• Several new, revised and withdrawn footnotes to the criteria in order to provide 

clarification.

• Revisions to the water quality standards provision at OAR 340-041-0033 which 

revise regulatory citations and table numbers referencing the human health and 

aquatic life criteria tables.

2. Revised arsenic human health criteria.

ODEQ adopted revised human health criteria for arsenic and submitted the revised 

criteria separately to EPA on July 12, 2011. 

3. New implementation provision entitled “Site-specific background pollutant criteria” 

at OAR 340-041-0033(6).

ODEQ adopted a new provision that allows it to develop a site-specific criteria for a 

portion of a waterbody in the vicinity of an NPDES permitted discharge in limited 

instances. The criteria is only applicable for criteria addressing carcinogenic effects on 

 

1 EPA. 2009. EPA National Recommended Water Quality Criteria. U.S. Environmental Protection Agency Office 

of Water. Office of Science and Technology. Available at: 

http://water.epa.gov/scitech/swguidance/standards/current/upload/nrwqc-2009.pdf 2 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, EPA-822-B-00-004. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf

3 EPA. 2001. Water Quality Criterion for the Protection of Human Health: Methylmercury. U.S. Environmental 

Protection Agency, Office of Water, Washington, D.C. EPA 823-R-01-001. Available at: 

http://www.epa.gov/waterscience/criteria/methylmercury/document.html
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

6 

human health and for pollutants that are taken into a facility through their intake water 

and discharged to the same waterbody at an equal or lower mass. The instream criterion 

concentration is limited to three percent above the ambient condition and may not 

exceed a 10-4 risk level as calculated using the same input variables as used to calculate 

the criteria in Table 40. 

4. Revised variance provision at OAR 340-041-0059.

ODEQ has removed the variance authorizing procedure found at OAR 340-041-0061(2) 

and replaced it with a new procedure at OAR 340-041-0059. ODEQ’s objective for 

these revisions was to ensure that variances and their accompanying pollutant reduction 

plans continue to ensure progress toward meeting standards, to streamline the 

administration process, and to require pollutant reduction plans with specific milestones 

that will result in water quality improvement, and add general clarification to the rule. 

All variances adopted under this provision require EPA approval.

5. A correction to a cross-reference in the bacteria provision found at OAR 340-041-

0009(10).

ODEQ adopted a revision to correct the cross-reference in this provision to reflect rule 

numbering revisions in OAR 340-041-0061.

6. Revised rules explaining how the mechanisms for forestry and agricultural nonpoint 

sources work to meet water quality standards and the total maximum daily load 

(TMDL) load at OAR 340-041-0007(5) and OAR 340-041-0061(9)(a)(E), (10), and 

(11).

ODEQ adopted revisions to clarify how nonpoint sources will be addressed in TMDLs 

and how ODEQ will interact with the Departments of Forestry and Agriculture to 

ensure needed programs are in place to address these sources of pollution. 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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II. ORGANIZATION OF DOCUMENT

This document is organized in the following manner. Part III of this document contains 

background on ODEQ’s process to adopt new and revised human health criteria and information 

regarding the July 12 and 21, 2011 submittals. 

Part IV contains the basis for EPA’s decisions under section 303(c) of the Clean Water Act 

(CWA) and implementing regulations found in the Code of Federal Regulations (CFR) at 40 

CFR § 131.11 to approve Oregon’s new and revised human health criteria. This section includes 

information regarding EPA’s review of Oregon’s human health criteria revisions which 

specifically evaluates the applicability of the human health criteria to Oregon’s waters along with

the methodology and input variables used by Oregon for their non-carcinogenic and carcinogenic 

criteria. This includes an evaluation of Oregon’s revised fish consumption rate of 175 grams per 

day used to derive the State’s new and revised human health criteria. Separate subsections 

include the EPA’s action on Oregon’s new methylmercury human health criteria and revised 

human health criteria for arsenic. Finally, this section outlines EPA’s review and action on new, 

revised and withdrawn footnotes, withdrawn human health criteria which were replaced by more 

specific criteria and the Table 40 summary language.

Part V of this document contains EPA’s review and action on revisions to Oregon’s narrative 

statement at OAR 340-041-0033. 

Parts VI and VII of the document contain EPA’s review and approval of two implementation 

procedures included in the July 21, 2011 submittal – the background pollutant criteria and the 

revised variance provision. 

Part VIII of this document includes EPA’s review and action on a minor editorial change to 

Oregon’s bacteria provision to correct a cross-referencing error.

Part IX discusses the revised rules regarding implementation of criteria by forestry and 

agricultural nonpoint sources. These provisions are not WQS under the CWA and therefore EPA 

is taking no action on them. 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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III. BACKGROUND

In 1999, ODEQ initiated a Water Quality Standards Review (triennial review) to update 

Oregon’s criteria for toxic pollutants which were based on the 1986 EPA Gold Book4 and that 

were contained in OAR 340-041-0033 and Table 20 of Oregon’s water quality standards. This 

review was completed in 2003. During this review, ODEQ made significant revisions to both 

their aquatic life and human health criteria based on the updated EPA methodologies and science 

for deriving aquatic life and human health criteria that had occurred since the Gold Book had 

been published. The Commission adopted these new and revised water quality standards on May 

20, 2004. Upon adoption, ODEQ submitted these criteria changes along with revisions to the 

narrative toxics provision to EPA on July 8, 2004. 

One goal of Oregon’s 1999-2003 WQS review was to update its human health criteria for toxic 

pollutants in order to reflect the latest scientific information and EPA’s most recent national 

CWA § 304(a) human health criteria recommendations.5

 In 2000, EPA published a revised 

methodology for deriving § 304(a) human health criteria recommendations titled Methodology 

for Deriving Ambient Water Quality Criteria for the Protection of Human Health (hereinafter 

referred to as the “2000 Methodology”).6 In separate updates published in 2002 and 20037,8

along with 2009,9 EPA updated the § 304(a) human health criteria recommendations to reflect 

this new methodology and to consider updated toxicological information in EPA’s Integrated 

Risk Information System (IRIS).10 

The new and revised human health criteria adopted by Oregon in 2004 were based on EPA’s 

recommendations provided in these documents. The human health criteria were derived using a 

fish consumption rate of 17.5 grams per day (about 0.6 ounces per day or three 6-ounce meals 

per month), which represents the 90th

 

4 EPA. 1986. Quality Criteria for Water (“Gold Book”). U.S. Environmental Protection Agency, Office of Water, 

Washington, D.C. EPA 440/5-86-001. Available at: 

 percentile of consumption among consumers and nonconsumers of fish nationwide. This is the national default fish consumption rate recommended 

http://www.epa.gov/waterscience/criteria/library/goldbook.pdf 5 ODEQ. 2003. Toxic Compounds Criteria: 1999-2003 Water Quality Standards Review Issue Paper. Oregon 

Department of Environmental Quality, Portland, Oregon. Available at: 

http://www.deq.state.or.us/about/eqc/agendas/attachments/may2004/5.20.04.ItemB.AttchH.pdf

6 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA-822-B-00-004. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 7 EPA. 2002. Revision of National Recommended Water Quality Criteria. U.S. Environmental Protection Agency, 

Office of Water, Washington, D.C. Federal Register, Volume: 67, Issue: 249, Page: 79091 (67 FR 79091), 

December 27, 2002. Available at: http://www.epa.gov/fedrgstr/EPA-WATER/2002/December/Day-27/w32770.htm 8 EPA. 2003. National Recommended Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. Federal Register, Volume: 68, Issue: 250, 

Page: 75507 (68 FR 75507), December 31, 2003. Available at: http://www.epa.gov/fedrgstr/EPAWATER/2003/December/Day-31/w32211.htm 9 EPA. 2009. EPA National Recommended Water Quality Criteria. U.S. Environmental Protection Agency Office 

of Water. Office of Science and Technology. Available at: 

http://water.epa.gov/scitech/swguidance/standards/current/upload/nrwqc-2009.pdf 10 EPA. Integrated Risk Information System (IRIS). U.S. Environmental Protection Agency, Office of Water, 

Washington, D.C. Available at: www.epa.gov/iris
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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by EPA in the 2000 Methodology for use when local, regional or other data is not available. 

During the public process Oregon received comment regarding concerns that the fish 

consumption rate used in the criteria may not accurately represent Oregonian’s consumption 

patterns. Following review of these comments ODEQ recommended, and in 2004 the 

Commission adopted, criteria derived using a fish consumption rate of 17.5 grams per day. 

However, in recognition of this expressed public concern, the Commission requested that ODEQ

seek resources to conduct a fish consumption rate study in Oregon. 

Following Oregon’s 2004 adoption of these criteria, the Confederated Tribes of the Umatilla 

Indian Reservation (Umatilla Tribe) and other tribal governments raised objections to EPA, 

stating that the criteria did not protect tribal members who eat higher amounts of fish and for 

whom fish consumption is a critical part of their cultural tradition and religion. In response, EPA 

evaluated the protectiveness of the criteria in light of local and regional fish consumption data 

and initiated discussions with Oregon regarding this issue. Local data was available from a study 

conducted by the Columbia River Inter-Tribal Fish Commission (CRITFC)11 (hereinafter 

referred to as the “CRITFC Study”), which included surveys of four Columbia River Tribes, two

of whom reside in Oregon, the Confederated Tribes of the Umatilla Indian Reservation (CTUIR

or Umatilla Tribe) and the Confederated Tribes of the Warms Springs Reservation. In addition, 

several regional fish consumption studies were also available. 

Oregon was not able to obtain funding for a study of Oregon fish consumption rates specific to 

Oregon but did agree to review available literature and data in collaboration with EPA and the 

Umatilla Tribe. In the fall of 2006, ODEQ launched the fish consumption rate review project 

involving seven public workshops and two workgroups. The workgroups were charged with 

providing ODEQ with information relative to the available science and the potential 

implementation and fiscal concerns that may be associated with criteria based on a higher fish 

consumption rate. The Human Health Focus Group (HHFG), made up of public health 

professionals and toxicologists, reviewed the available data on fish consumption patterns in the 

Pacific Northwest and elsewhere. The group wrote a report12 summarizing the science and made 

recommendations about the quality and appropriate use of the available information. ODEQ

considered the HHFG’s analysis and the other information obtained during this project to select a 

fish consumption rate they felt appropriate for use in developing criteria for Oregon’s waters. 

Oregon addressed several issues during the process of determining an appropriate fish 

consumption rate for Oregon. These included: 

• Which studies should be considered when developing a fish consumption rate for 

Oregon? 

• Should the criteria be based on a fish consumption rate that includes Oregonians who 

 

11 Columbia River Inter-Tribal Fish Commission (CRITFC). October 1994. A Fish Consumption Survey of the 

Umatilla, Nez Perce, Yakama, and Warm Springs Tribes of the Columbia River Basin. Technical Report 94.3. 

Available at: http://www.critfc.org/tech/94-3report.pdf 12 ODEQ. June 2008. Human Health Focus Group Report. Oregon Fish and Shellfish Consumption Rate Project.

Oregon Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/HHFGFinalReportJune2008.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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eat large amounts of fish and shellfish for cultural, economic, health or other reasons, or 

a fish consumption rate reflective of Oregon’s total (general) population, including 

people who do not eat fish or eat it rarely? 

• What proportion or percentile of the population(s) should be protected by the criteria? 

(Within any group, whether Native-Americans, Asian-Americans, commercial 

fishermen or the general population, there will be some individuals who eat more than 

any chosen rate and some who eat less than that rate.)

• How should the consumption of salmon (an anadromous fish) and/or marine fish be 

considered when determining the rate to be used for freshwaters? 

• Should the same rate be used for all waters of Oregon or should multiple rates be 

considered based on known consumption patterns? 

Following review of all the information obtained during the fish consumption rate review 

project, ODEQ determined that a fish consumption rate of 175 grams per day was a reasonable 

and protective fish consumption rate to use when driving the human health criteria applicable to 

Oregon’s surface waters. A fish consumption rate of 175 grams per day equals approximately 6.2 

ounces per day (or approximately 23 8-oz fish or shellfish meals per month). This rate represents 

the 95th percentile value from the CRITFC study and is within the range of the 90th percentile 

values from various studies from the Northwest assembled by the HHFG.

13 ODEQ found the 

175 grams per day rate to be consistent with the HHFG recommendation to use 90th or 95th 

percentile values to represent the proportion of the population the criteria should be designed to 

protect. ODEQ also found the rate to be consistent with HHFG recommendations to use a fish 

consumption rate that represents fish consumers only, rather than a rate derived from the overall 

population including both consumers and non-consumers of fish, and to include salmon and 

other marine species in the rate. Finally, ODEQ recommended that the rate be applied 

statewide.14 

On October 23, 2008, ODEQ presented the EQC with a recommendation to revise Oregon’s 

toxics criteria for human health using a FCR of 175 grams per day.

15

1. Revise Oregon’s toxics criteria for human health based on a fish consumption rate of 175 

grams per person per day; 

 The Commission agreed 

with this recommendation and directed ODEQ to: 

 

13 EPA. June 1, 2010. Technical Support Document for Action on the State of Oregon’s New and Revised Human 

Health Water Quality Criteria for Toxics and Revisions to Narrative Toxics Provisions Submitted on July 8, 2004. 

U.S. Environmental Protection Agency. See Appendix A for a summary of the studies considered by Oregon. 

Available at: http://www.epa.gov/region10/pdf/water/oregon-hhwqc-tsd_june2010.pdf 14 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. 

pages 8-10. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf 15 ODEQ. October 6, 2008. Memo from Dick Pederson, Director ODEQ, to the Environmental Quality 

Commission. Agenda Item G, Action Item: Oregon’s Fish Consumption Rate – For Use in Setting Water Quality 

Standards for Toxic Pollutants October 23, 2008 EQC Meeting. Oregon Department of Environmental Quality. 

Available at: http://www.deq.state.or.us/about/eqc/agendas/attachments/2008oct/ItemG.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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2. Propose rule language that will allow ODEQ to implement the standards in National 

Pollutant Discharge Elimination System (NPDES) permits and other Clean Water Act 

programs in an environmentally meaningful and cost-effective manner; 

3. Propose rule language or develop other implementation strategies to reduce the adverse 

impacts of toxic substances in Oregon’s waters that are the result of non-point source (not 

via a pipe) discharges or other sources not subject to section 402 of the Clean Water Act; 

4. Develop a proposed rule and implementation methods that carefully consider the costs 

and benefits of the fish consumption rate and the data and scientific analysis already 

compiled or that is developed as part of the rulemaking proceeding. 

Pursuant to this directive, ODEQ established a Rulemaking Workgroup in December 2008. The 

purpose of this group was to provide input and feedback to ODEQ as it developed its proposed 

rulemaking to revise human health criteria using the revised fish consumption rate and to address 

potential issues associated with implementing the revised criteria. The workgroup met on a 

monthly basis from December 2008 until October 2010. In addition, to address the third element 

of the EQC directive, ODEQ formed other workgroups to address the reduction of toxic 

pollution from sources not regulated by NPDES permits and to assist in the development of a 

comprehensive, cross media toxics reduction strategy.16 

On December 21, 2010, ODEQ issued a proposed rule for public comment that included new and 

revised human health criteria for toxic pollutants, a revision to their variance rule, a new 

background pollutant provision and several proposed additions and revisions to rules relating to 

the implementation of the NPDES program and nonpoint source programs. As detailed in 

Section I, ODEQ revised the proposed rule in response to comments received, presented it to the 

Commission for adoption on June 16, 2011, and submitted it to EPA on July 21, 2011. 

On June 1, 2010, consistent with a Consent Decree entered in the U.S. District Court in the 

District of Oregon,

17 EPA acted on the revised human health criteria which Oregon had 

submitted to EPA on July 8, 2004. As part of this action, EPA disapproved all of Oregon’s new 

and revised human health criteria that were derived using a fish consumption rate of 17.5 grams 

per day as well as three footnotes associated with those criteria and footnote K insofar as it 

applies to the “organism only” human health criterion for manganese. EPA found that these

human health criteria, derived using a fish consumption rate of 17.5 grams per day, were not 

protective of Oregon’s designated use of fishing consistent with the Commission’s October 2008 

directive. In the June 1, 2010 letter to ODEQ, EPA stated that it “believe[d] that Oregon’s 

adoption of human health criteria consistent with the Commission’s Directive to develop criteria 

using a fish consumption rate of 175 grams per day statewide would be adequate to address 

EPA’s disapproval of the new and revised human health criteria as well as [3 of the 4]

footnotes.”18

 

16 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. pages 8-9. Available 

at: 

 As part of the 2010 action, EPA approved the human health criteria for asbestos 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf 17 Northwest Environmental Advocates v. U.S. EPA, No. 06-479-HA (D. Or. 2006). 18 EPA. June 1, 2010. Letter from Michael A. Bussell, Director, Office of Water and Watersheds, EPA Region 10 to 

Neil Mullane, Administrator, Water Quality Division, ODEQ, Re: EPA's Action on New and Revised Human 

Health Water Quality Criteria for Toxics and Revisions to Narrative Toxics Provisions in Oregon’s Water Quality 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

12

and copper since those criteria value were not derived based on a fish consumption rate, footnote 

K as it applies to the “water + organism criteria for iron and manganese, the withdrawal of eight 

human health criteria, and revisions to the narrative toxic provisions at OAR 340-041-0033(1) 

and (2). 

A. ODEQ’S JULY 12 AND JULY 21, 2011 SUBMITTALS

In order to address the Commission’s October 2008 directive and EPA’s June 1, 2010 

disapproval action, on July 21, 2011 Oregon submitted new and revised numeric human health 

criteria and two WQS implementation provisions to EPA for action under CWA §303(c). This 

submission also contained a correction to a regulatory citation in the bacteria criteria provision 

and several other regulatory changes that are not WQS. Revised criteria for arsenic were 

adopted separately by the Commission on April 21, 2011 and submitted to EPA on July 12, 

2011. All of the numeric criteria adopted in these actions were derived using a fish consumption 

rate of 175 grams per day. 

The new and revised criteria, which serve as the basis for NPDES permit limits and other 

regulatory decisions, are located in Oregon’s WQS in a new table called Table 40. ODEQ has 

consolidated the human health criteria which were previously contained in Tables 20, 33A and 

33B into Table 40. The adoption of the new and revised human health criteria based on a fish 

consumption rate of 175 grams per day is ODEQ’s remedy to EPA’s disapproval of ODEQ’s 

2004 human health criteria based on a fish consumption rate of 17.5 grams per day. 

Consistent with CWA §303(c)(2)(B), in adopting these new and revised human health criteria, 

Oregon has adopted human health criteria for all of the priority toxic pollutants for which EPA 

has published criteria under CWA §304(a). Forty-eight of the 104 pollutants for which Oregon 

adopted new or revised human health criteria are characterized as non-carcinogens (i.e., not 

having the potential to cause cancer). The remaining 56 pollutants are carcinogens (i.e., having 

the potential to cause cancer). 

The calculations that Oregon used to derive the human health criteria for non-carcinogens and 

carcinogens differed depending upon the primary exposure pathway appropriate to the pollutant 

for which the criteria were derived and are further described separately in section IV below. 

Oregon’s criteria were adopted to protect human health from chronic (lifetime) exposure to toxic 

substances through drinking water and eating fish19

 

Standards. Available at: 

obtained from surface waters. Where the 

criteria are derived to protect human health from exposure through both drinking water and 

eating fish (in combination), Oregon has adopted “water + organism” criteria. Where the criteria 

are derived to protect human health from exposure through eating fish alone (not in combination 

with drinking water), Oregon has adopted “organism only” criteria. These two sets of criteria 

(i.e., “water + organism” and “organism only”) are reflected in the column headings of Table 40 

http://www.deq.state.or.us/wq/standards/docs/toxics/EPAHHLetter20100601.pdf 19 As used throughout this technical support document, the term “fish” refers to finfish as well as shellfish.
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

13

in Oregon’s WQS. Additional information can be found in ODEQ’s Human Health Criteria 

Issue Paper.20

The criteria adopted by Oregon for methylmercury and arsenic were derived using variations to 

the methodology used for all other criteria. Thus, those two pollutants and the methods used to 

derive those criteria are addressed separately below.

Additional revisions related to the human health criteria, which are discussed below, include: 

• The removal of 13 pollutants consistent with EPA’s removal of 304(a) recommended 

criteria values for these same pollutants. Most of the previous criteria recommendations 

addressed families of pollutants for which the criteria recommendations were withdrawn 

when EPA developed criteria recommendations for the individual pollutants within each

family of chemicals that present the greatest human health risk. 

• Several new, revised and withdrawn footnotes to the criteria in order to provide 

clarification.

• Revisions to the water quality standards provision at OAR 340-041-0033 which provide 

narrative language explaining the human health and aquatic life criteria tables.

In response to the second, third and forth directives issued by the EQC on October 23, 2008, 

ODEQ also revised OAR 340-041 to include two WQS implementation provisions - a revised 

variance procedure and a site-specific background pollutant provision – and revised rule 

language addressing implementation for nonpoint sources. In addition, ODEQ adopted an intake 

credit rule (an NPDES permitting provision) and several changes to the TMDL rules in OAR 

340-042 and 045. These latter changes were not submitted to EPA for consideration under CWA 

303(c), are not WQS under the CWA, and are not addressed in this action. 

 

20 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. 

Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

14

IV. ODEQ’S NEW AND REVISED HUMAN HEALTH CRITERIA

A. EPA REVIEW OF OREGON’S HUMAN HEALTH CRITERIA 

REVISIONS

This section contains the basis for EPA’s decisions under section 303(c) of the CWA and 

implementing regulations found at 40 CFR § 131.11 to approve Oregon’s new and revised 

human health criteria. This section includes information regarding EPA’s review of Oregon’s 

human health criteria revisions which specifically evaluates the applicability of the human health 

criteria to Oregon’s waters along with the methodology and input variables used by Oregon for 

their non-carcinogenic and carcinogenic criteria. This includes an evaluation of Oregon’s 

revised fish consumption rate of 175 grams per day. Separate subsections address EPA’s action 

on Oregon’s new methylmercury human health criteria and revised human health criteria for 

arsenic. Finally, this section outlines EPA’s review and action on new, revised and withdrawn 

footnotes, withdrawn human health criteria which were replaced by more specific criteria and the 

Table 40 summary language.

1. Human Health Criteria Applicability to Oregon’s Waters

Oregon’s water quality standards designate beneficial uses for waters of the state for each basin 

in OAR 340-041-0101 to 0340 and Tables 101(A) through 340(A), incorporated into Oregon rule 

by reference. Oregon’s designated uses consist of the following: 

• Public Domestic Water Supply 

• Private Domestic Water Supply

• Industrial Water Supply 

• Irrigation

• Livestock Watering 

• Fish and Aquatic Life

• Wildlife and Hunting 

• Fishing 

• Boating

• Water Contact Recreation

• Aesthetic Quality

• Hydro Power 

• Commercial Navigation and Transportation 

Oregon’s human health criteria were developed to protect human health from long-term exposure 

to toxic pollutants in drinking water and through eating fish and shellfish containing these 

pollutants. Waters to be protected for drinking water are those designated as either “Public 

Domestic Water Supply” or “Private Domestic Water Supply.” Waters to be protected for 

consumption of fish and shellfish are designated as “Fishing.” 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

15

Oregon’s “water + organism” criteria were established to limit the pollutant to levels that protect 

the safe consumption of drinking water and fish, including shellfish. These criteria are applied 

where Oregon has designated public or private domestic water supply, and fishing as beneficial 

uses. Table 1 below identifies those waters in Oregon that have both a fishing designated use 

and either a public domestic water supply or a private domestic water supply designated use. 

Both the “water + organism” criteria and the “organism only” criteria apply to these waters.

The “organism only” criteria apply where Oregon has designated a fishing use but not a domestic 

or private water supply use.21 Table 2 below identifies those waters in Oregon that have a 

fishing designated use but neither a public domestic water supply nor a private domestic water 

supply designated use. 

Table 1: Waters in Oregon that have both a fishing designated use as well as a public domestic 

water supply or a private domestic water supply designated use. Both the “water + organism” 

criteria and the “organism only” criteria apply to these waters.

OR WQS 

Table No. Basin Name Segment Names

101A Mainstem Columbia River Columbia River (Mouth to RM 86); and Columbia River 

(RM 86 to 309) 

121A Mainstem Snake River Snake River (RM 176 to 409)

130A Deschutes Basin

Deschutes River Main Stem from Mouth to Pelton 

Regulating Dam; Deschutes River Main Stem from Pelton 

Regulating Dam to Bend Diversion Dam and for the 

Crooked River Main Stem; Deschutes River Main Stem 

above Bend Diversion Dam and for the Metolious River 

Main Steam; and All Other Basin Stems

140A Goose and Summer Lakes 

Basin Freshwater Lakes and Reservoirs; and Freshwater Streams

151A Grande Ronde Basin Main Stem Grande Ronde River (RM 39 to 165) and All 

Other Basin Waters 

160A Hood Basin Hood River Basin Streams

170A John Day Basin John Day River and All Tributaries

180A Klamath Basin

Klamath River from Klamath Lake to Keno Dam (RM 

255 to 232.5); Lost River (RM 5 to 65) and Lost River 

Diversion Channel; and All Other Basin Waters

190A Malheur Lake Basin All Rivers and Tributaries

 

21 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. page 

11. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf 

Also described in ODEQ. 2004. Toxic Compounds Criteria. 1999-2003 Water Quality Standards Review. Issue 

Paper. May 20-21, 2004 EQC Meeting. Agenda Item B, Rule Adoption: Water Quality Standards, including Toxics 

Criteria. Attachment H. Oregon Department of Environmental Quality. pages H-14, H-17. Available at: 

http://www.deq.state.or.us/about/eqc/agendas/attachments/may2004/5.20.04.ItemB.AttchH.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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OR WQS 

Table No. Basin Name Segment Names

201 A Malheur River Basin

Malheur River from Namorf to Mouth; Malheur River 

from Beulah Dam and Warm Springs Dams to Namorf; 

Willow Creek from Brogan to Mouth; Willow Creek from 

Malheur Reservoir to Brogan; Bully Creek from Reservoir 

to Mouth; Malheur Reservoir, Bully Creek Reservoir, 

Beulah Reservoir, Warm Springs Reservoir; and Malheur 

River and Tributaries Upstream from Reservoirs

220A Mid Coast Basin Fresh Waters

230A North Coast Basin All Other Streams and Tributaries Thereto

250A Owyhee Basin

Owyhee River (RM 0 to 18); Owyhee River (RM 18 to 

Dam); Antelope Reservoir, Cow Creek Reservoir, and 

Owyhee Reservoir; Owyhee River and Tributaries 

Upstream from Owyhee Reservoir; Main Stem of the 

South Fork of the Owyhee River from the Oregon-Idaho 

River border to Three Forks (the confluence of the North, 

Middle, and South Forks of Owyhee River); and Main 

Stem Owyhee River from Crooked Creek (RM 22) to the 

mouth of Birch Creek (RM 76)

260A Powder/Burnt Basin All Basin Waters

Rogue River Main Stem from Estuary to Lost Creek Dam; 

Rogue River Main Stem above Lost Dam and Tributaries; 

and All Other Tributaries to Rogue River and Bear Creek

286A Sandy Basin Sandy River; and All Other Tributaries to Sandy River

300A South Coast Basin All Streams and Tributaries Thereto

310A Umatilla Basin

Umatilla Sub-basin; Willow Creek Sub-basin; Umpqua 

River Main Stem from Head of Tidewater to Confluence 

of North and South Umpqua Rivers; North Umpqua River 

Main Stem; South Umpqua River Main Stem; and All 

Other Tributaries to Umpqua, North Umpqua, and South 

Umpqua Rivers

330A Walla Walla Basin

Walla Walla River Main Stem from Confluence of North 

and South Forks to State Line; and All Other Basin 

Streams

340A Willamette Basin

Main Stem Willamette River from Mouth to Willamette 

Falls, including Multnomah Channel; Main Stem 

Willamette River from Willamette Falls to Newberg; 

Main Stem Willamette River from Newberg to Salem; 

Main Stem Willamette River from Salem to Coast Fork; 

Clackamas River; Molalla River; Santiam River; 

McKenzie River; Tualatin River; and All Other Streams 

and Tributaries
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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Table 2: Waters in Oregon that have a fishing designated use but neither a public domestic water 

supply nor a private domestic water supply designated use. “Organism only” criteria apply to 

these waters.

OR WQS 

Table No. Basin Segment Name

140A Goose and Summer Lakes 

Basin

Goose Lake; and Highly Alkaline and Saline Lakes

190A Malheur Lake Basin Natural Lakes

220A Mid Coast Basin Estuaries and Adjacent Marine Waters

230A North Coast Basin Estuaries and Adjacent Marine Waters

271A Rogue Basin Rogue River Estuary and Adjacent Marine Waters; and 

Bear Creek Main Stem

286A Sandy Basin Streams Forming Waterfalls Near Columbia River 

Highway

300A South Coast Basin Estuaries and Adjacent Marine Waters

320A Umpqua Basin Umpqua River Estuary to Head of Tidewater and Adjacent 

Marine Waters

Oregon’s application of human health criteria is consistent with EPA’s guidance to states and the 

methodology inherent in developing the criteria. EPA’s Water Quality Standards Handbook

recommends that states adopt human health criteria to protect waters designated for public water 

supply. In addition, for waters where fish ingestion is considered an important activity, EPA 

recommends that the criterion applicable to fish consumption be applied to protect the use.22 

Oregon’s human health criteria are applied consistent with this recommendation. 

EPA has published guidelines for developing criteria that protect human health endpoints and 

separate criteria guidance to protect aquatic life endpoints. Consistent with the science used to 

derive the criteria, EPA recommends that human health criteria be applied to uses where human 

health could be affected by exposure from consumption of water and/or aquatic life and aquatic 

life criteria be applied to uses associated with the protection of aquatic life. Thus, most states, 

including Oregon, have adopted two sets of criteria for toxic pollutants, one to address the effects 

to human health and the other to address the effects to aquatic life. For some pollutants, this 

results in a waterbody segment having multiple criteria for a single pollutant, in which case the 

WQS require the attainment of all of the applicable criteria. 

Oregon’s human health criteria are developed pursuant to methods presented in EPA’s 2000 

Human Health Methodology.23

 

22 EPA. 1994. Water Quality Standards (WQS) Handbook: Second Edition. August 1994. United States 

Environmental Protection Agency, Office of Water. EPA-823-B-94-005a. page 3-15. Available at 

 These criteria take into consideration the cancer potency or 

systemic toxicity of a pollutant, the exposure related to surface water exposure and a risk 

characterization. The criteria generated pursuant to the 2000 Human Health Methodology 

protect humans from toxicological effects from chronic exposure to a pollutant through drinking 

water or from eating fish living in a water body to which the criteria apply. 

http://water.epa.gov/scitech/swguidance/standards/handbook/index.cfm

23 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. EPA822-B-00-004. Available at: http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

18

EPA’s guidance for developing aquatic life criteria recommends that such criteria use toxicity 

information for aquatic life, establishing pollutant levels necessary for protection of aquatic life 

from both short and long term effects of the pollutant.24

 

 Toxicity tests are used to evaluate 

pollutant effects on survival, growth and reproduction of aquatic organisms. 

EPA has reviewed Oregon’s new and revised human health criteria in order to assess whether 

they are sufficient to protect Oregon’s designated uses from human health impacts associated 

with the pollutants for which they were adopted. Other endpoints and uses (e.g., Fish and 

Aquatic Life) are addressed by other provisions in Oregon’s WQS and are not before the Agency 

for review under § 303(c)(3) of the CWA as part of this action. 

2. Non-Carcinogens: Criteria Methodology and Input Variables 

Used by Oregon25 

EPA’s 2000 Human Health Methodology provides guidance for deriving human health criteria 

for toxic pollutants.26 Pursuant to Section 304(a) of the CWA, EPA has published a table of 

recommended criteria for use by states in adopting and revising criteria.27 For each pollutant, 

this table also identifies whether EPA recommends the methodology specific to carcinogens or 

non-carcinogens, based on information relative to the human health endpoints of greatest 

significance.

28 For criteria recommendations for non-carcinogens, the values in this table reflect 

criteria derived using the ‘national default’ values identified in the 2000 Methodology: the 

reference dose (RfD) contained in the Integrated Risk Information System (IRIS) at the time of 

publication; the use of EPA’s recommended bioconcentration factors (BCFs) (as opposed to sitespecific bioaccumulation factors (BAFs)); and relative source concentration factors (RSC) as 

provided by the latest 304(a) recommendations. 

While the 2000 Methodology provides national default values, it also provides guidance 

necessary to adjust criteria to reflect local conditions and encourages states to use the guidance to 

appropriately reflect local conditions and/or protect identifiable subpopulations.29

 

24 EPA. 1985. Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic 

Organisms and Their Uses. Available at: 

 Numerous 

states have adopted criteria derived through the use of site-specific input variables instead of the 

national default values, thus ensuring the criteria are protective of the human health uses 

http://water.epa.gov/scitech/swguidance/standards/criteria/aqlife/upload/85guidelines.pdf

25For methylmercury, Oregon used an alternate approach that will be addressed in a separate section.

26 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. EPA822-B-00-004. Available at: http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 27 EPA. National Recommend Ambient Water Quality Criteria for the Protection of Aquatic Life and Human Health. 

Published pursuant to section 304(a) of the Clean Water Act. Available at: 

http://www.epa.gov/waterscience/criteria/wqctable/index.html

28 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 822-B-00-004. pages 1-3. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf

29 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 822-B-00-004. pages iii, 1-11. 

Available at: http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

19

designated in the waters where those criteria apply.

Criteria calculated pursuant to the 2000 Methodology are derived by applying a number of 

pollutant-specific and general risk-assessment values to an equation that generates a criteria 

protective of human health uses. Where a state uses this equation to develop criteria, the 

protectiveness of those criteria are dependent on whether the values used for each input variable 

are appropriate for protection of the uses specific to a pollutant and/or waterbody. With the 

exception of the methylmercury criterion, Oregon has directly applied this equation when 

deriving the new or revised human health criteria for the non-carcinogenic pollutants included in 

EPA’s 2009 table of 304(a) criteria recommendations.30 A simplified version of this equation is 

provided in Figure A below, followed by a discussion of the variables in the equation and the 

values utilized by Oregon to derive their new and revised criteria, and supporting information 

provided by Oregon. EPA’s review of the protectiveness of the criteria is contained in a later 

subsection. 

Figure A: Simplified version of the equation used by Oregon in deriving the human health 

criteria for non-carcinogens. 

a) Reference Done (RfD) 

For non-carcinogens, EPA’s 2000 Methodology recommends deriving human health criteria 

using a reference dose. A reference dose is defined as “an estimate (with uncertainty spanning 

approximately an order of magnitude) of a daily exposure to the human population (including 

sensitive subgroups) that is likely to be without appreciable risk of deleterious effects over a 

lifetime.”31

 

30 EPA. 2009. EPA National Recommended Water Quality Criteria. U.S. Environmental Protection Agency Office 

of Water. Office of Science and Technology. Available at: 

 In other words, individuals should not suffer from appreciable risks of deleterious 

effects if their exposure to a chemical is at or below the reference dose for that chemical. Thus, 

http://water.epa.gov/scitech/swguidance/standards/current/upload/nrwqc-2009.pdf 31 EPA. 1993. Reference Dose (RfD): Description and Use in Health Risk Assessments. Integrated Risk Information 

System (IRIS). Intra-Agency Reference Dose (RfD) Work Group, Office of Health and Environmental Assessment, 

Environmental Criteria and Assessment Office, U.S. Environmental Protection Agency, Cincinnati, OH. Available 

at: http://www.epa.gov/ncea/iris/rfd.htm

AWQC = RfD • RSC • (BW)________ 

 [DI + (FCR • BAF)]

where: 

AWQC = Ambient Water Quality Criterion (milligrams per liter) 

RfD = Reference dose for noncancer effects (milligrams per 

 kilogram per day)

RSC = Relative source contribution factor to account for non- 

 water sources of exposure (unitless) 

BW = Human body weight (kilograms) 

DI = Drinking water intake (liters per day)

FCR = Fish Consumption Rate (kilograms per day) 

BAF = Bioaccumulation factor (liters per kilogram)
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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the reference dose serves as a threshold level and is specific to each individual pollutant. 

In deriving both the “water + organism” and “organism only” criteria for non-carcinogens, 

Oregon utilized the most recent reference doses recommended by EPA’s current § 304(a) 

criteria.

b) Body Weight (BW)

Oregon used EPA’s national default value of 70 kilograms for the body weight as recommended 

in the 2000 Methodology. The source of data for the human body weight value of 70 kilograms 

is the National Health and Nutrition Examination Survey (NHANES) conducted between 1988 

and 1994 using a nationwide probability sample of over 30,000 persons. Body weights of 73 

percent of those individuals included in the survey were carefully measured by survey staff (i.e., 

weights were not self-reported). The mean body weight value for men and women ages 18-74 

years old from this survey was 75.6 kilograms. Another survey by the National Cancer Institute 

measured a mean body weigh value of 70.5 kilograms for adults aged 20-64 years old, and 

EPA’s Exposure Factors Handbook recommends 71.8 kilograms for adults based on an earlier 

NHANES survey.32 While these data are slightly higher than 70 kilograms, the derivation of 

cancer slope factors identified in EPA’s IRIS database are based upon a body weight of 70 

kilograms. Since consistency is advocated between the dose-response relationship and the 

exposure factors, a default value of 70 kilograms was recommended by EPA for use in deriving 

human health water quality criteria.

33

c) Drinking Water Intake Rate (DI)

Oregon used EPA’s national default value of two liters per day for the drinking water intake rate

as recommended in the 2000 Methodology. This rate was based on the 1994-1996 Continuing 

Survey of Food Intake by Individuals (hereinafter referred to as the “CSFII survey”) conducted 

by the U.S. Department of Agriculture. This rate represents the 86th percentile of drinking water 

intake data for adults collected from the CSFII survey.34

d) Bioaccumulation/Bioconcentration Factor (BAF/BCF)

 While this rate was utilized for “water 

+ organisms” criteria, a drinking water intake rate of zero liters per day was used for “organism 

only” criteria because the criteria are not intended to address human health effects from the 

consumption of drinking water.

Bioconcentration factors (BCF) describe the uptake and retention of a pollutant by an aquatic 

organism from water only while bioaccumulation factors (BAF)describe the uptake and retention 

of a pollutant by an aquatic organism from all sources (e.g., water, ingestion, and sediment). The 

 

32 EPA. 1997. Exposure Factors Handbook. U.S. Environmental Protection Agency, National Center for 

Environmental Assessment, Office of Research and Development, Washington, D.C. EPA/600/P-95/002Fa. 

Available at: http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=12464 33 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 822-B-00-004. pages 4-18 to 4-19.

Available at: http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 34 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 822-B-00-004. pages 4-21 to 4-22. 

Available at: http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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magnitude of bioconcentration or bioaccumulation by aquatic organisms varies widely 

depending upon the pollutant but can be extremely high for some highly persistent and 

hydrophobic pollutants. For highly bioaccumulative pollutants, concentrations in aquatic 

organisms may pose unacceptable human health risks from fish consumption even when 

concentrations in water are too low to cause unacceptable health risks from drinking water 

consumption alone. EPA’s 2000 Human Health Methodology recommends the use of national 

BAFs in the calculation of ambient water quality criteria. However, to date, EPA has only 

provided guidance on the calculation of national BAFs. BAF values have not been calculated for 

individual pollutants. EPA uses bioconcentration factors in their nationally recommended 

criteria. As explained below, States have the option to use these BCFs or to calculate BAFs 

using guidance documents published by EPA. 

EPA’s 2000 Human Health Methodology provides guidance on developing bioaccumulation 

factors for the protection of human health.35 A subsequent technical support document to the 

2000 Methodology entitled Technical Support Document Volume 2: Development of National 

Bioaccumulation Factors (2003) provides added detail to the BAF calculation procedures 

outlined in the Methodology.36 In 2009, EPA published the Technical Support Document 

Volume 3: Development of Site-Specific Bioaccumulation Factors. This document provides 

guidance on different approaches that investigators can take to develop site-specific BAFs, and 

the factors that should be considered when selecting an approach for a given situation.37

EPA recommends that states use these methods when adopting human health criteria. Neither of 

the bioaccumulation technical support documents should be used alone to derive BAFs but 

should be used in conjunction with the 2000 Human Health Methodology. The bioaccumulation 

methodology documents encourage developing site-specific BAFs because EPA recognizes that 

BAFs vary not only between chemicals and trophic levels, but also among different ecosystems 

and waterbodies. National average BAF values for a given chemical and trophic level may not 

provide the most accurate estimate of bioaccumulation for certain water bodies in the United 

States. At a given location, the BAF for a chemical may be higher or lower than the national 

BAF, depending on the nature and extent of site-specific influences. 

 

While EPA’s 2000 Human Health Methodology recommends the use of bioaccumulation factors 

in deriving human health criteria, development of bioaccumulation factors is a time and resource 

intensive process and BAFs can vary from site-to-site. Thus, it is difficult to develop BAFs on a 

national or statewide scale and this has rarely been done. Therefore, until such time as 

 

35 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA-822-B-00-004. Section 5. Available 

at: http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 36 EPA. December 2003. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human 

Health (2000). Technical Support Document Volume 2: Development of National Bioaccumulation Factors. 

Available at: 

http://water.epa.gov/scitech/swguidance/standards/upload/2005_05_06_criteria_humanhealth_method_tsdvol2.pdf 37 EPA. September 2009. Methodology for Deriving Ambient Water Quality Criteria for Protection of Human 

Health (2000). Technical Support Document Volume 3: Development of Site-Specific Bioaccumulation Factors. 

Available at: 

http://water.epa.gov/scitech/swguidance/standards/criteria/health/methodology/upload/2008_07_01_criteria_human

health_method_tsdvol3.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

22

bioaccumulation factors are developed, EPA’s national CWA § 304(a) human health criteria 

guidance values continue to be based upon the use of bioconcentration factors which reflect the 

uptake and retention of a pollutant by an aquatic organism from water alone. Given the lack of 

any Oregon-specific BAFs and consistent with EPA guidance, Oregon utilized bioconcentration 

factors instead of bioaccumulation factors in deriving its new and revised human health criteria. 

The bioconcentration factors utilized by Oregon are pollutant-specific and are consistent with the 

bioconcentration factors recommended by EPA in the most recent national CWA § 304(a) 

human health criteria recommendations. 

e) Fish Consumption Rate (FC)

When establishing a single value/criterion as a regulatory endpoint, States and EPA must make 

several policy decisions relative to the members of the population that will be protected when 

using the waters for activities protected by the designated uses and the established criteria. In 

EPA’s 2000 Human Health Methodology, EPA provides guidance to the States on the use of 

local and regional data to develop an appropriate fish consumption rate for the use in criteria 

derivation and encourages the states to use this data to determine the level of protection 

appropriate for State waters. 

Between 2006 and 2008 Oregon conducted extensive outreach and information gathering and 

consulted with a group of public health experts (the Human Health Focus Group (HHFG)) in 

order to inform their decision-making regarding an appropriate fish consumption rate for use in 

developing human health criteria for Oregon. Based on the information gathered in this effort 

and the review of available fish consumption studies, ODEQ concluded that a fish consumption 

rate of 175 grams per day (about 23, 8 ounce fish meals per month) is a protective rate to use as 

the basis for Oregon’s human health criteria. Oregon found that this rate reflected the goal of 

providing sufficiently clean water in the state such that people who wish to regularly eat fish for 

cultural, health or economic reasons may do so without risk of adverse health effects due to 

contaminants contained in the fish.38 

Further detail regarding Oregon’s process, information considered and the decision to use a fish 

consumption rate of 175 grams per day is available in Oregon’s Human Health Criteria Issue 

Paper and the Human Health Focus Group Report and outlined in a separate EPA memo.

39

 

38 ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 

Quality Standards Implementation Policies. Oregon Department of Environmental Quality. page 21. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf 

ODEQ. June 2, 2011. Memorandum from Dick Pedersen to Environmental Quality Commission; Agenda item C, 

Rule adoption: Revised water quality standards for human health and revised water quality standards 

implementation policies, June 15-17, EQC meeting. Oregon Department of Environmental Quality. page 5.

Available at: http://www.deq.state.or.us/about/eqc/agendas/attachments/2011june/C-WQStdsStaffRpt.pdf 39 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. At: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf

ODEQ. June 2008. Human Health Focus Group Report. Oregon Fish and Shellfish Consumption Rate Project.

Oregon Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/HHFGFinalReportJune2008.pdf 

EPA. October 17, 2011. Memorandum from Jannine Jennings to Record. Fish Consumption Rate Analysis – 

Oregon’s New and Revised Human Health Water Quality Criteria for Toxics and Associated Implementation 

Provisions Submitted July 12 and 21, 2011.
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

23

f) Relative Source Contribution (RSC)

Criteria for pollutants that are non-carcinogens are based on a total cumulative dose over time 

that causes an observable effect. Because the human health water quality criteria address 

exposure only through drinking water and eating fish and not from other sources (e.g. skin 

absorption, inhalation, other foods and occupational exposure), a relative source contribution 

(RSC) factor is used to calculate the criteria. The RSC represents the proportion of exposure 

from water and fish relative to the total exposure (including water and fish - and other exposures 

such as air, food, dermal, etc.). This estimate allows for adjustment of the criteria value to reflect 

exposure from only water and fish. This is intended to make sure that the total exposure from all 

sources does not exceed the reference dose for lifetime exposure. 

Developing an RSC value for a pollutant requires an evaluation of both the sources of potential 

exposure and quantifying the relative exposure from each source. EPA has derived RSC values 

for 17 of the pollutants with 304(a) recommended human health criteria. Most of these RSC 

values were developed by EPA’s drinking water program under the Safe Drinking Water Act. 

Oregon used 15 of the 17 RSC values recommended by EPA. These 15 RSC values are listed in 

table 5 below. Oregon chose to use RSC values that vary from those recommended by EPA for

endrin (80% instead of 20%, discussed in more detail below) and methylmercury (a value of zero

instead of 2.7 x 10-5 mg methylmercury/kg/day, discussed in the methylmercury section below). 

Table 5: Criteria where Oregon applied EPA’s recommended RSC values.

Pollutant RSC Value

Antimony 40%

Chlorobenzene 20%

Chlorodibromomethane 80%

Cyanide 20%

Ethylbenzene 20%

gamma-BHC (Lindane) 20%

Hexachlorcyclopentadiene 20%

Thallium 20%

Toluene 20%

1,1,2-Trichloroethane 20%

1,1-Dichloroethylene 20%

1,2,4-Trichlorobenzene 20%

1,2-Dichlorobenzene(o) 20%

1,2-trans-Dichloroethylene 20%

1,4-Dichlorobenzene(p) 20%

RSC for Endrin 

EPA’s recommended RSC value of 20% for endrin was developed by the drinking water 

program and takes into account exposure through multiple pathways. Endrin is a pesticide that 

was banned under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) in the 1980s, 

thus limiting current sources of exposure. Following the review of available data and 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

24

information, ODEQ determined that an RSC of 80% was appropriate for use in deriving the 

human health criteria for endrin.40 Oregon’s rationale is described below. 

Due to the chemical properties of endrin and its prohibition by FIFRA in the 1980s, ODEQ 

believes it is unlikely that people in Oregon would gain only 20% of their exposure from water 

and fish while gaining 80% of their exposure from other sources identified in the RSC 

calculation performed by EPA and used in EPA’s recommended 304(a) criteria.41 The 80% RSC 

calculation for endrin used by Oregon accounts for the two main sources of exposure which they 

considered to have a potential to impact human health in Oregon: (1) drinking water and (2) the 

bioconcentration of endrin in aquatic organisms and thus potential accumulation in fish tissue. 

ODEQ found that the other sources or routes of exposure to endrin considered by EPA were not 

expected to occur in Oregon for the following reasons: 

1) The use of endrin has been banned in the US since the 1980s. Endrin is not mobile in 

soil, it volatizes into the air rapidly, and has a conservative half life estimate in soil of 14 

years. 

2) The U.S. Food and Drug Administration concluded in 1995 that exposure to endrin 

through food products was no longer a concern, thus reducing concerns regarding 

exposure to endrin from food sources. 

3) The one possible route of exposure to endrin that was identified in the literature was at 

hazardous waste sites where endrin has been detected in contaminated soils; however, no 

such sites were identified in Oregon. 42,43 

Based on the above considerations, Oregon found that human health exposure to endrin through 

routes other than fish tissue and drinking water is unlikely. In addition, although endrin 

bioconcentrates in aquatic organisms, it is not very soluble in water and therefore is not likely to 

be found in drinking water sources. Since the bioconcentration factor used to derive the human 

health criteria is very high (3970), the endrin criteria values for “water + organism” and 

“organism only” are the same when rounded to significant digits.44

 

40 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. 

pages 14-15. Available at: 

 Therefore, Oregon 

concluded that the primary routes of exposure for endrin are anticipated to be through 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf 41 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. 

pages 14-15. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf 42 U.S. Department of Health and Human Services. August 1996. Toxicological Profile for Endrin. Public Health 

Service. Agency for Toxic Substances and Disease Registry. Available at: 

http://www.atsdr.cdc.gov/toxprofiles/tp89.pdf

43 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. 

pages 14-15. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf 44 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. 

pages 14-15. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

25

bioconcentration in aquatic organisms and its accumulation in fish tissue. These two exposure 

routes have already been accounted for through the BCF and fish consumption rate. 

The purpose of the RSC is to ensure that the level of a chemical allowed by a criterion or 

multiple criteria, when combined with other identified sources of exposure common to the 

population of concern, will not result in exposures that exceed the RfD.45 Where a state reviews 

exposure data and develops an alternate RSC value, EPA recommends that the RSC not be lower 

than 20% or higher than 80%.46 Where it can be demonstrated that other sources and routes of 

exposure are not anticipated for the chemical in question (based on information about its 

known/anticipated uses and chemical/physical properties), EPA recommends a ceiling of 80%. 

This 80% ceiling is a way to provide adequate protection for those who experience exposures 

(from any or several sources) higher than available data may indicate.47 Oregon adjusted the 

RSC value for endrin to 80% consistent with this guidance.48

3. Carcinogens: Criteria Methodology and Input Variables Used 

by Oregon49 

As noted above, EPA’s 2000 Methodology provides guidance for deriving human health criteria 

for toxic pollutants50 and has published a table of recommended criteria for use by states in 

adopting and revising criteria.51 For human health criteria, the values in this table reflect criteria 

derived using all of the ‘national default’ values identified in the 2000 Methodology, the 

reference dose (RfD) contained in the Integrated Risk Information System (IRIS) at the time of 

publication, the use of EPA’s recommended bioconcentration factors (BCFs), relative source 

contribution factors (RSC) as provided by the latest 304(a) recommendations and a 10-6

carcinogenic risk factor. While the 2000 Methodology provides national default values, it also 

provides necessary guidance to adjust criteria to reflect local conditions and encourages states to 

use the guidance to appropriately reflect local conditions and/or protect identifiable 

subpopulations.52

 

45 November 3, 2000. Federal Register, Volume: 65, Issue: 214, pages: 66472-3 (65 FR 66472-3). Available at: 

 Numerous states have adopted criteria derived through the use of site-specific 

input variables or a carcinogenic risk level other than 1x10-6. 

http://www.epa.gov/fedrgstr/EPA-WATER/2000/November/Day-03/w27924.htm 46 November 3, 2000. Federal Register, Volume: 65, Issue: 214, pages: 66472-3 (65 FR 66472-3). Available at: 

http://www.epa.gov/fedrgstr/EPA-WATER/2000/November/Day-03/w27924.htm 47 November 3, 2000. Federal Register, Volume: 65, Issue: 214, pages: 66472-3 (65 FR 66472-3). Available at: 

http://www.epa.gov/fedrgstr/EPA-WATER/2000/November/Day-03/w27924.htm 48 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. 

pages 14-15. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf 49 Note: For arsenic, Oregon used an alternate approach that will be addressed in section IV.E of this document. 50 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA-822-B-00-004. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 51 EPA. National Recommend Ambient Water Quality Criteria for the Protection of Aquatic Life and Human Health. 

Published pursuant to section 304(a) of the Clean Water Act. Available at: 

http://www.epa.gov/waterscience/criteria/wqctable/index.html 52 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 822-B-00-004. pages iii, 1-11. 

Available at: http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

26

For carcinogens, EPA’s 2000 Methodology recognizes that states have the flexibility to adopt 

human health criteria within a risk level range of 1 x 10-6 to 1 x 10-5, as long as highly exposed 

populations would at least be protected at the 1 x 10-4 (1:10,000) risk level. Furthermore, the 

2000 Methodology recognizes that states have the flexibility to adopt human health criteria that 

protect the general population at a more protective risk level or target the protection of a higher 

proportion of its population at the targeted risk level. Oregon’s new and revised criteria for 

carcinogens (except arsenic) target the protection of high consumers at the 1 x 10-6 risk level 

through the use of a fish consumption rate representative of the 95th percentile consumption from 

a study of a highly exposed subpopulation. 

 

EPA’s 2000 Methodology describes procedures that can be used as guidance by states for 

deriving human health water criteria. The 2000 Methodology includes an equation that Oregon

used in deriving the “water + organism” and “organism only” new and revised human health 

criteria for 56 carcinogens. A simplified version of this equation is provided below in Figure B. 

Descriptions of the variables included in these equations, and the values that Oregon utilized for 

each variable, are also provided below. 

Figure B: Simplified version of the equation used by Oregon in deriving the human health 

criteria for carcinogens.

a) Body Weight, Drinking Water Intake Rate, 

Bioaccumulation/Bioconcentration Factor and Fish 

Consumption Rate

Four of the input variables used by Oregon in deriving its numeric human health water quality 

criteria for carcinogens are the same as those used by Oregon in deriving its numeric human 

health water quality criteria for non-carcinogens. A body weight of 70 kilograms and a drinking 

water intake of two liters per day were used, consistent with the default values that EPA utilized 

in deriving its national CWA § 304(a) human health criteria guidance values. Oregon also used 

bioconcentration factors consistent with those used by EPA in deriving its national CWA § 

304(a) human health criteria guidance values. 

Consistent with the criteria for non-carcinogens, a fish consumption rate of 175 grams per day 

was used in deriving the new and revised human health criteria for carcinogens. This value was 

AWQC = ___(Risk Level • BW)____ 

[CSF • (DI + (FCR • BAF))]

where: 

AWQC = Ambient Water Quality Criterion (milligrams per liter) 

Risk Level = Risk level (unitless)

CSF = Cancer slope factor (milligrams per kilogram per day) 

BW = Human body weight (kilograms) 

DI = Drinking water intake (liters per day)

FCF = Fish Consumption Rate (kilograms per day)

BAF = Bioaccumulation factor (liters per kilogram) 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

27

used by Oregon following an evaluation of local and regional data (discussed in greater detail 

above). 

b) Cancer Slope Factor

For toxic pollutants identified as carcinogens and assumed to exhibit a linear dose-response 

relationship at low doses, EPA derives its national CWA § 304(a) human health criteria 

recommendations to correspond to incremental lifetime cancer risk levels, applying a risk 

management policy that ensures a reasonable level of protection for the general population.53

Accordingly, a cancer slope factor is included in the calculation. A cancer slope factor expresses 

incremental, lifetime risk of cancer as a function of the rate of intake of the contaminant, and is 

combined with exposure assumptions to express that risk in terms of an ambient water 

concentration. Cancer slope factors are specific to individual pollutants. In deriving both the 

“water + organism” and “organism only” human health criteria for carcinogens, Oregon utilized 

the cancer slope factors recommended by EPA. 

 

c) Carcinogenic Risk Level 

EPA has identified a risk level range of 1 x 10-6 (1:1,000,000) to 1 x 10-5 (1:100,000) to be an 

appropriate risk management goal for the general population. EPA characterizes this acceptable 

risk range as the “upper-bound estimate of excess lifetime cancer risk,” ranging from one case in 

a population of one million to one case in a population of one hundred thousand. The nationally 

recommended 304(a) criteria are intended to protect the general population at a cancer risk of 1 x 

10-6. 

EPA’s 2000 Methodology states that criteria based on a 10-5 risk level are acceptable for the 

general population as long as States and authorized Tribes ensure that the risk to more highly 

exposed subgroups (sport fishers or subsistence fishers) does not exceed the 10-4 risk level. If a 

state does not find that the 1 x 10-6 risk level adequately protects highly exposed populations, it 

has the flexibility to adopt water quality criteria based on a more stringent risk level or at a level 

more representative of highly exposed population groups. This flexibility extends to all variables 

used to calculate the criteria. 54 

Except where specifically identified, Oregon’s new and revised human health criteria for 

carcinogens are calculated using a risk level of 1 x 10-6 (1:1,000,000). As discussed earlier, these 

criteria include the use of a fish consumption rate of 175 grams per day, a level representative of 

high fish consumers in the state. Oregon’s goal in adopting the criteria was to protect high end 

consumers (as opposed to the general population) at a risk level of 10-6. 

 

53 EPA. 2000. Revisions to the Methodology for Deriving Ambient Water Quality Criteria for the Protection of 

Human Health (2000). U.S. Environmental Protection Agency, Office of Water, Washington, D.C. Federal 

Register, Volume: 65, Issue: 214, page: 66443 (65 FR 66443), November 3, 2000. Available at: 

http://www.epa.gov/fedrgstr/EPA-WATER/2000/November/Day-03/w27924.htm 54 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 822-B-00-004. page 2-6. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

28

4. EPA Review of Input Variables for All New and Revised Human 

Health Criteria except Methylmercury and Arsenic55

As discussed above, EPA’s 2000 Human Health Methodology provides guidance for deriving 

human health criteria for toxic pollutants. For each variable used in the criteria calculation, EPA 

provides a “national default value” and guidance on specific adjustments that may be necessary 

to reflect local conditions and/or protect identifiable subpopulations. As part of evaluating 

whether Oregon’s criteria protect the designated uses, EPA looked at the input values used by 

Oregon and whether there was Oregon-specific information relative to each value that should be 

considered in the review. 

EPA has not identified any local or regional data to indicate that the national values used by 

Oregon for the reference dose, relative source contribution, body weight, drinking water intake 

rate, or bioaccumulation factors are inappropriate for use in Oregon. 

EPA’s review indicates that there is local and regional fish consumption data available and that it 

should be considered consistent with EPA’s 2000 Methodology. The 2000 Methodology 

recognizes the variability of fish consumption rates among population groups and by geographic 

region. In employing the 2000 Methodology to derive criteria, EPA urges States and Tribes to 

use a fish intake level derived from local or regional data instead of the national default 

recommendation to ensure the fish intake level chosen is protective of highly exposed 

subpopulations. A four preference hierarchy concerning the use of fish consumption rate data is 

set forth: (1) use of local data; (2) use of data reflecting similar geography/population groups; 

(3) use of data from national surveys; and (4) use of EPA's default intake rate. 

As discussed in greater detail above, in 1996 Oregon initiated an extensive review of the fish 

consumption rate used for deriving its human health criteria. This process resulted in ODEQ and 

the Commission determining that a fish consumption rate of 175 grams per day was a reasonable 

and protective fish consumption rate to use as the basis for Oregon’s human health criteria. 

EPA has reviewed the available information and the basis for ODEQ’s determination and has 

found that Oregon has considered all relevant local and regional data, applied that data consistent 

with EPA’s 2000 Methodology to select a fish consumption rate that would result in a level of 

protection consistent with that recommended by EPA in the 2000 Methodology. Thus, EPA 

finds that the FCR utilized to derive Oregon’s criteria is consistent with EPA’s recommendations 

in the 2000 Methodology. 

B. EPA ACTION ON ODEQ’S NEW HUMAN HEALTH CRITERIA

ODEQ has adopted new human health criteria for 41 pollutants (excluding methylmercury which 

is discussed in further detail below). Previously, Oregon did not have EPA-approved values for 

these criteria in their WQS. These new criteria, found in Table 40 of Oregon’s WQS, are 

 

55 Methylmercury and arsenic are addressed in sections IV.D and IV.E of this document.
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

29

consistent with EPA’s current 304(a) criteria recommendations and utilize the 175 grams per day 

fish consumption rate. 

Table 6: Oregon’s new human health criteria.

No. Pollutant Carcinogen Water + Organism 

(μg/L)

Organism Only 

(μg/L)

1 Acenaphthene 95 99

2 Anthracene 2900 4000

3 Benzo(a)anthracene  0.0013 0.0018

4 Benzo (a)pyrene  0.0013 0.0018

5 Benzo(b)fluoranthene 3,4  0.0013 0.0018

6 Benzo(k)fluoranthene  0.0013 0.0018

7 Bromoform  3.3 14

8 Butylbenzyl phthalate 190 190

9 Chlorobenzene 74 160

10 Chlorodibromomethane  0.31 1.3

11 Chloronaphthalene 2 150 160

12 Chlorophenol 2 14 15

13 Chrysene  0.0013 0.0018

14 DDD 4,4’  0.000031 0.000031

15 DDE 4,4’  0.000022 0.000022

16 DDT 4,4’  0.000022 0.000022

17 Dibenzo(a,h)anthracene  0.0013 0.0018

18 Dichlorobenzene(o) 1,2 110 130

19 Dichlorobenzene(p) 1,4 16 19

20 Dichlorobromomethane  0.42 1.7

21 Dichloroethylene 1,1 230 710

22 Dichloroethylene trans 1,2 120 1000

23 Dichloropropane 1,2  0.38 1.5

24 Dimethylphenol 2,4 76 85

25 Dinitrophenol 2,4 62 530

26 Dinitrophenols 62 530

27 Diphenylhydrazine 1,2  0.014 0.020

28 Endosulfan alpha 8.5 8.9

29 Endosulfan beta 8.5 8.9

30 Endosulfan sulfate 8.5 8.9

31 Endrin aldehyde 0.030 0.030

32 Fluorene 390 530

33 Heptachlor epoxide  0.0000039 0.0000039

34 Indeno(1,2,3-cd)pyrene  0.0013 0.0018

35 Methyl bromide 37 150

36 Methyl-4,6-dinitrophenol 2 9.2 28

37 Methylene chloride  4.3 59

38 Nitrosodi-n-propylamine, N  0.0046 0.051

39 Pyrene 290 400

40 Trichlorobenzene 1,2,4 6.4 7.0

41 Zinc 2100 2600
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

30

EPA Approval 

In accordance with its Clean Water Act authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, 

EPA approves Oregon’s new human health toxic criteria for these 41 pollutants that are

consistent with EPA’s current CWA § 304(a) criteria recommendations because they are 

protective of Oregon’s fishing and water supply designated uses.

EPA Rationale

EPA’s WQS regulations at 40 C.F.R. 131 require that criteria protect the designated uses. As 

noted previously, Oregon’s human health criteria apply to waters with fishing and water supply 

uses and thus must be established at a level that will protect those uses. Therefore, EPA must 

evaluate whether the criteria protect Oregon’s human health uses. 

EPA’s 2000 Human Health Methodology provides guidance for deriving human health criteria 

for toxic pollutants. For each variable used in the criteria calculation, EPA provides a “national 

default value” and guidance on specific adjustments that may be necessary to reflect local 

conditions and/or protect identifiable subpopulations. As part of evaluating whether Oregon’s 

criteria protect the designated uses, EPA looked at the input values used by Oregon and whether 

there was Oregon-specific information relative to each value that should be considered in the 

review. As discussed above EPA has found that ODEQ has appropriately considered local and 

regional data in selecting input variables for use in deriving the criteria identified in Table 6. 

The 2000 Methodology document provides an extensive technical basis and justification as to 

how EPA’s recommended human health criteria adequately protect human health uses. Oregon’s 

new criteria were developed consistent with these recommendations, therefore, EPA has 

determined that Oregon’s new criteria protect human health uses in accordance with 40 C.F.R. 

Part 131.11(a)(1). 

C. EPA ACTION ON ODEQ’S REVISED HUMAN HEALTH CRITERIA

ODEQ has adopted revised human health criteria for 62 pollutants (excluding arsenic which is 

described in further detail below). These revised criteria, found in Table 40 of Oregon’s WQS, 

are consistent with EPA’s current 304(a) criteria recommendations and utilize the 175 grams per 

day fish consumption rate. 

Table 7: Oregon’s revised human health criteria.

No. Pollutant Carcinogen Water + Organism 

(μg/L)

Organism Only 

(μg/L)

1 Acrolein56 0.88 0.93

2 Acrylonitrile  0.018 0.025

3 Aldrin  0.0000050 0.0000050

4 Antimony 5.1 64

 

56 Based on June 10, 2009 updates to EPA’s IRIS system, Oregon’s previous ADI value of 15.6 ug/kgram per day

was replaced with an RfD value of 5.0 x 10-4. EPA. Integrated Risk Information System (IRIS). U.S. Environmental 

Protection Agency, Office of Water, Washington, D.C. Available at: www.epa.gov/iris
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

31

No. Pollutant Carcinogen Water + Organism 

(μg/L)

Organism Only 

(μg/L)

5 Benzene  1.6 5.1

6 Benzidine  0.000018 0.000020

7 BHC Alpha  0.00045 0.00049

8 BHC Beta  0.0016 0.0017

9 BHC Gamma (Lindane) 0.17 0.18

10 Carbon tetrachloride  0.10 0.16

11 Chlordane  0.000081 0.000081

12 Chloroethyl ether bis 2  0.020 0.05

13 Chloroform57 260 1100

14 Chloroisopropyl ether bis 2 1200 6500

15 Chloromethyl ether, bis  0.000024 0.000029

16 CyanideG 130 130

17 Dichlorobenzene(m) 1,3 80 96

18 Dichlorobenzidine 3,3’  0.0027 0.0028

19 Dichloroethane 1,2  0.35 3.7

20 Dichlorophenol 2,4 23 29

21 Dichloropropene 1,3  0.30 2.1

22 Dieldrin  0.0000053 0.0000054

23 Diethyl phthalate 3800 4400

24 Dimethyl phthalate 84000 110000

25 Di-n-butyl phthalate 400 450

26 Dinitrotoluene 2,4  0.084 0.34

27 Dioxin (2,3,7,8-TCDD)  0.00000000051 0.00000000051

28 Endrin 0.024 0.024

29 Ethylbenzene 160 210

30 Ethylhexyl phthalate bis 2  0.20 0.22

31 Fluoranthene 14 14

32 Heptachlor  0.0000079 0.0000079

33 Hexachlorobenzene  0.000029 0.000029

34 Hexachlorobutadiene  0.36 1.8

35 Hexachlorocyclo-hexaneTechnical 0.0014 0.0015

36 Hexachlorocyclopentadiene 30 110

37 Hexachloroethane  0.29 0.33

38 Isophorone  27 96

39 Nickel58 140 170

40 Nitrobenzene 14 69

41 Nitrosamines  0.00079 0.046

 

57 Based on June 10, 2009 updates to EPA’s IRIS system, Oregon’s previous q1* value of 6.1 x 10-3 was replaced 

with an RfD value of 0.01 mg/kgrams per day. EPA. Integrated Risk Information System (IRIS). U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. Available at: www.epa.gov/iris 58 Oregon’s revised human health criteria for nickel are less stringent than Oregon’s previous values despite 

Oregon’s adoption of a 175 grams per day fish consumption rate. However, the equation used to calculate the 

revised criteria is consistent with EPA’s current 304(a) recommendations. It is unclear how ODEQ derived their 

previous values for nickel. Nonetheless, EPA assessed protectiveness of the revised criteria using EPA’s 304(a) 

recommendations and Oregon’s human health designated uses.
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

32

No. Pollutant Carcinogen Water + Organism 

(μg/L)

Organism Only 

(μg/L)

42 Nitrosodibutylamine, N  0.0050 0.02

43 Nitrosodiethylamine, N  0.00079 0.046

44 Nitrosodimethylamine, N  0.00068 0.30

45 Nitrosodiphenylamine, N  0.55 0.60

46 Nitrosopyrrolidine, N  0.016 3.4

47 Pentachlorobenzene 0.15 0.15

48 Pentachlorophenol  0.15 0.30

49 Phenol59 9400 86000

50 Polychlorinated biphenyls 

(PCBs)L 

 0.0000064 0.0000064

51 Selenium60 120 420

52 Tetrachlorobenzene 1,2,4,5- 0.11 0.11

53 Tetrachloroethane 1,1,2,2  0.12 0.40

54 Tetrachloroethylene  0.24 0.33

55 Thallium 0.043 0.047

56 Toluene 720 1500

57 Toxaphene  0.000028 0.000028

58 Trichloroethane 1,1,2  0.44 1.6

59 Trichloroethylene  1.4 3.0

60 Trichlorophenol 2,4,5- 330 360

61 Trichlorophenol 2,4,6  0.23 0.24

62 Vinyl chloride  0.02 0.24

Footnote G: They cyanide criterion is expressed as total cyanide (CN)/L

Footnote L: This criterion applies to total PCBs (e.g. determined as Aroclors or congeners). 

EPA Approval 

In accordance with its Clean Water Act authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, 

EPA approves Oregon’s revised human health toxic criteria for these 62 pollutants, consistent 

with EPA’s current CWA § 304(a) criteria recommendations, because they are protective of 

fishing and water supply uses.

EPA Rationale

EPA’s WQS regulations require that criteria protect the designated uses. As noted previously, 

Oregon’s human health criteria apply to waters with fishing and water supply uses and thus must 

be established at a level that will protect those uses. Therefore, EPA must evaluate whether the 

criteria protect Oregon’s human health uses. 

 

59 Based on updates to EPA’s IRIS system, the RfD value of 6.0 x 10-1 was replaced by Oregon with an RfD value 

of 3.0 x 10-1. EPA. Integrated Risk Information System (IRIS). U.S. Environmental Protection Agency, Office of 

Water, Washington, D.C. Available at: www.epa.gov/iris 60 Oregon’s revised human health criteria for selenium are less stringent than Oregon’s previous values despite 

Oregon’s adoption of a 175 grams per day fish consumption rate. However, the equation used to calculate the 

revised criteria is consistent with EPA’s current 304(a) recommendations. It is unclear how ODEQ derived their 

previous values for these two pollutants. Nonetheless, EPA assessed protectiveness of the revised criteria using 

EPA’s 304(a) recommendations and Oregon’s human health designated uses.
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

33

EPA’s 2000 Human Health Methodology provides guidance for deriving human health criteria 

for toxic pollutants. For each variable used in the criteria calculation, EPA provides a “national 

default value” and guidance on specific adjustments that may be necessary to reflect local 

conditions and/or protect identifiable subpopulations. As part of evaluating whether Oregon’s 

criteria protect the designated uses, EPA reviewed the input values used by Oregon and whether 

there was Oregon-specific information relative to each value that should be considered in the 

review. As discussed above EPA has found that ODEQ has appropriately considered local and 

regional data in selecting input variables for use in deriving the criteria identified in Table 7. 

EPA provides an extensive technical basis and justification as to how its recommended human 

health criteria adequately protect human health uses in EPA’s 2000 Methodology document. 

Oregon’s revised criteria were developed consistent with these recommendations, therefore, EPA 

has determined that Oregon’s revised criteria protect human health uses in accordance with 40 

C.F.R. Part 131.11(a)(1). 

D. METHYLMERCURY CRITERION

1. Methylmercury: Criteria Methodology and Input Variables 

Used by Oregon 

On January 8, 2001, EPA published61 a new national CWA § 304(a) human health criterion 

recommendation for methylmercury62 which replaced EPA’s previous recommendations for total 

mercury. The new recommendation is expressed as a fish tissue value, thus reflecting the latest 

science that indicates consumption of contaminated fish and shellfish is the primary human route 

of exposure to methylmercury. 

In 1980, EPA published a water quality criterion for total mercury. The criterion was partially 

updated in 1997 to incorporate a change in the reference dose (RfD). Consistent with Section 

304(a) of the Clean Water Act, EPA periodically revises water quality criteria to reflect the latest 

scientific knowledge on the type and extent of identifiable effects on human health from the 

presence of pollutants in a waterbody. In 2001, EPA completed a review of the water quality 

criterion for protection of human health for methylmercury. This criterion recommendation 

considered the bioaccumulation of methylmercury as well as the latest science and data 

regarding health effects from intake of mercury and the primary routes of exposure. The new 

criterion for methylmercury was derived consistent with the Methodology for Deriving Ambient 

Water Quality Criteria for the Protection of Human Health (2000). The 2001 recommendation 

 

61 EPA. January 8, 2001. Water Quality Criteria: Notice of Availability of Water Quality Criterion for the 

Protection of Human Health: Methylmercury. U.S. Environmental Protection Agency, Office of Water, 

Washington, D.C. Federal Register, Volume: 66, Issue: 5, page: 1344 (66 FR 1344). Available at: 

http://www.epa.gov/fedrgstr/EPA-WATER/2001/January/Day-08/w217.htm 62 EPA. January 2001. Water Quality Criterion for the Protection of Human Health: Methylmercury. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 823-R-01-001. Available at: 

http://www.epa.gov/waterscience/criteria/methylmercury/document.html
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

34

is expressed as a fish tissue concentration for methylmercury and replaces the water column 

concentration for mercury that was contained in EPA’s previous recommendation.63 

As part of the 2001 reevaluation of the mercury criterion, EPA evaluated the sources and form of 

mercury that humans are exposed to when eating fish or consuming water from the nation’s 

waters. It was found that humans are exposed primarily to methylmercury rather than to 

inorganic mercury and that the dominant exposure pathway is through consumption of 

contaminated fish and shellfish rather than from ambient water.64 EPA found that if a criterion 

addressed the potential health effects from methylmercury, it would protect humans from the 

most toxic form of mercury and the primary route of exposure. Thus, in considering the fate of 

mercury in the environment and available toxicological data, EPA concluded that it is more 

appropriate to derive a water quality criterion for methylmercury rather than inorganic mercury. 

In addition, “EPA believes that the latest data and science on methylmercury exposure, effects, 

and environmental fate support the derivation of a fish tissue residue criterion,” instead of a 

water column criterion.65

“Methylmercury is highly bioaccumulative and is the form of mercury that bioaccumulates most 

efficiently in the aquatic food web. Methylation of mercury is a key step in the entrance of 

mercury into food chains. The biotransformation of inorganic mercury species to methylated 

organic species in water bodies can occur in the sediment and the water column. Inorganic 

mercury can be absorbed by aquatic organisms but is generally taken up at a slower rate and with 

lower efficiency than is methylmercury.”66

“Methylmercury continues to accumulate in fish as they age. Predatory organisms at the top of 

aquatic and terrestrial food webs generally have higher methylmercury concentrations because 

methylmercury is typically not completely eliminated by organisms and is transferred up the 

food chain when predators feed on prey; for example, when a largemouth bass feeds on a bluegill 

sunfish, which fed on aquatic insects and smaller fish, all of which could contain some amount of 

methylmercury that gets transferred to the predator. Nearly 100 percent of the mercury that 

bioaccumulates in upper trophic level fish (predator) tissue is methylmercury (Bloom, 1992; 

Akagi, 1995; Kim, 1995; Becker and Bigham, 1995.)”67

 

63 EPA. January 2001. Water Quality Criterion for the Protection of Human Health: Methylmercury. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 823-R-01-001. page 1-1. Available at: 

http://www.epa.gov/waterscience/criteria/methylmercury/document.html

64 EPA. January 8, 2001. Water Quality Criteria: Notice of Availability of Water Quality Criterion for the 

Protection of Human Health: Methylmercury. U.S. Environmental Protection Agency, Office of Water, 

Washington, D.C. Federal Register, Volume: 66, Issue: 5, Page: 1344 (66 FR 1344). page 1345. Available at:

http://www.epa.gov/fedrgstr/EPA-WATER/2001/January/Day-08/w217.htm 65 EPA. January 2001. Water Quality Criterion for the Protection of Human Health: Methylmercury. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 823-R-01-001. page 1-2. Available at: 

http://www.epa.gov/waterscience/criteria/methylmercury/document.html 66 EPA. January 8, 2001. Water Quality Criteria: Notice of Availability of Water Quality Criterion for the 

Protection of Human Health: Methylmercury. U.S. Environmental Protection Agency, Office of Water, 

Washington, D.C. Federal Register, Volume: 66, Issue: 5, Page: 1344 (66 FR 1344). page 1348. Available at:

http://www.epa.gov/fedrgstr/EPA-WATER/2001/January/Day-08/w217.htm 67 EPA. January 8, 2001. Water Quality Criteria: Notice of Availability of Water Quality Criterion for the 

Protection of Human Health: Methylmercury. U.S. Environmental Protection Agency, Office of Water, 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

35

In consideration of the environmental fate of mercury, a fish tissue residue water quality criterion 

was found to be appropriate for many reasons. “Such a criterion integrates spatial and temporal 

complexity that occurs in aquatic systems and that affects methylmercury bioaccumulation. A 

fish tissue residue water quality criterion is more closely tied to the CWA goal of protecting the 

public health because it is based directly on the dominant human exposure route for 

methylmercury. The concentration of methylmercury is also generally easier to quantify in fish 

tissue than in water and is less variable over the time periods in which water quality standards 

are typically implemented in water quality-based. Thus, the data used in permitting activities can 

be based on a more consistent and measurable endpoint. A fish tissue residue criterion is also 

consistent with how fish advisories are issued. Fish advisories for mercury are based on the 

amount of methylmercury in fish tissue that is considered acceptable, although they are usually 

issued for a certain fish or shellfish species in terms of a meal size. A fish tissue residue water 

quality criterion should enhance harmonization between these two approaches for protecting the 

public health.”68 

Consistent with EPA’s 304(a) recommendation published in 2001, Oregon has replaced its 

“water + organism” and “organism only” water column human health criteria for total mercury 

with a new fish tissue-based “organism only” human health criterion for methylmercury. Similar 

to the 2000 Methodology, the computation of the methylmercury criterion uses several input 

variables, described in Figure C below. 

Figure C: Simplified version of the equation used by Oregon in deriving its new fish tissuebased “organism only” human health criterion for methylmercury. 

In the 2001 methylmercury criteria document, EPA strongly encourages States and authorized 

Tribes to consider developing a criterion using local or regional data over the default values if 

they believe that appropriate for protection of the target population. EPA recommends that these 

 Washington, D.C. Federal Register, Volume: 66, Issue: 5, Page: 1344 (66 FR 1344). page 1348. Available at:

http://www.epa.gov/fedrgstr/EPA-WATER/2001/January/Day-08/w217.htm 68 EPA. January 2001. Water Quality Criterion for the Protection of Human Health: Methylmercury. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 823-R-01-001. page xv. Available at: 

http://www.epa.gov/waterscience/criteria/methylmercury/document.html

TRC = (RfD – RSC) • (BW)_ 

 (FCR)

where: 

TRC = Fish Tissue Residue Criterion (milligrams per kilogram)

RfD = Reference dose for noncancer effects (milligrams per 

 kilogram per day) = 0.0001mg/kg-day 

RSC = Relative source contribution factor to account for nonwater sources of exposure (milligrams per kilogram per day) = 0

BW = Human body weight (kilograms) = 70 kg 

FCR = Fish Consumption Rate (kg/day) = 175 g/day 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

36

adjustments be applied consistent with the guidance provided in the 2000 Human Health 

Methodology.69

Consistent with EPA’s recommendation, Oregon replaced its “water + organism” and “organism 

only” water column human health criteria for total mercury with a new fish tissue-based 

“organism only” human health criterion for methylmercury equal to 0.040 micrograms per 

kilogram (mg/kg). In deriving this new criterion, Oregon used the equation below and the 

following values for each variable: reference dose equal to 0.0001 milligrams per kilogram per 

day; relative source contribution of 0; body weight equal to 70 kilograms and; fish consumption 

rate equal to 175 grams per day. As discussed in greater detail above, the reference dose and 

body weight are the values recommended by EPA and the fish consumption rate was derived 

using local and regional data. The RSC is discussed below. 

a) Relative Source Contribution (RSC) for Methylmercury 

Following review of available data and information specific to the exposure pathways for 

methylmercury, Oregon used EPA’s subtraction method to derive an RSC of zero for use in 

deriving the human health criterion for methylmercury.70 

In establishing a recommended RSC value, EPA found that the most significant source of 

exposure to methylmercury was the ingestion of marine fish. EPA also found that the estimated 

exposure from ambient water, drinking water, nonfish dietary foods, air, and soil were all, on 

average, at least several orders of magnitude less than those from marine fish ingestion. 

Therefore, these later exposure pathways were not factored into EPA’s recommended RSC 

value. An RSC of 2.7 x 10-5 mg methylmercury/kg/day is recommended by EPA as an estimated 

exposure from marine fish intake.71 

EPA’s above recommendation is based on the assumption that the fish consumption rate does not 

include fish of marine origin (as would be the case for most inland states/waters and is true of 

EPA’s national default value for fish consumptions of 17.5 grams per day). However, as part of 

Oregon’s reevaluation of local and regional data and the selection of a fish consumption rate of 

175 grams per day, Oregon did take into consideration the consumption of salmon (an 

anadromous species identified as marine in the CSFII study) and regional consumption rates that 

included estuarine finfish and shellfish. Therefore, in reviewing this information, Oregon 

determined that it was not necessary to provide additional protection from ingestion of marine 

fish through the use of an RSC value. As a result, Oregon subtracted out the exposure related to 

marine fish, resulting in an RSC of zero. 

 

69 EPA. January 2001. Water Quality Criterion for the Protection of Human Health: Methylmercury. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 823-R-01-001, page 7-2. Available at: 

http://www.epa.gov/waterscience/criteria/methylmercury/document.html

70 November 3, 2000. Federal Register, Volume: 65, Issue: 214, pages: 66472-3 (65 FR 66472-3). Available at: 

http://www.epa.gov/fedrgstr/EPA-WATER/2000/November/Day-03/w27924.htm 71 EPA. January 2001. Water Quality Criterion for the Protection of Human Health: Methylmercury. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 823-R-01-001. page xiv. Available at: 

http://www.epa.gov/waterscience/criteria/methylmercury/document.html
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

37

EPA’s 2000 Human Health Methodology recognizes that if States include marine fish in the fish 

consumption rate they may need to adjust the RSC consistent with this decision to appropriately 

represent overall exposure to a pollutant. 

“States and Tribes need to ensure that when evaluating overall exposure to a contaminant, [and 

that] marine fish intake is not double-counted with the other dietary intake estimate used. 

Coastal States and authorized Tribes that believe accounting for total fish consumption (i.e., 

fresh/estuarine and marine species) is more appropriate for protecting the population of concern 

may do so, provided that the marine intake component is not double-counted with the RSC 

estimate.” 72 

Oregon’s use of the subtraction method for deriving the RSC for methylmercury is consistent 

with this guidance. 

2. New human health criteria for methylmercury

Oregon has adopted the following new criterion for methylmercury: 

Table 8: Oregon’s criterion for methylmercury.

Pollutant Carcinogen Water + Organism 

(μg/L)

Organism Only 

(μg/L)

Methylmercury (mg/kg)J -- 0.040 (mg/kg)

Footnote J: This value is expressed as the fish tissue concentration of methylmercury. 

Contaminated fish and shellfish is the primary human route of exposure to methylmercury. 

Oregon’s new criterion of 0.040 mg/kg is expressed as a fish tissue residue concentration, not a 

water column concentration as all other human health criteria adopted by Oregon. Thus, when 

applying the criterion, ODEQ may need to consider data collected from either the water column 

or fish tissue or express a limitation as a water column value (e.g. provide a discharger with an 

effluent limit in an NPDES permit that can be measured in their effluent). Recognizing this fact, 

EPA has encouraged “states and authorized tribes to develop a methylmercury criterion 

implementation plan to ensure environmentally protective and effective administration of all 

water quality related programs with respect to methylmercury”. Furthermore, to assist the States 

in this process, in April 2010 EPA published recommended methods for implementing these 

criteria. 73 In recognition of this need, Oregon’s Human Health Criteria Issue Paper states that 

“...DEQ intends to develop implementation procedures similar to EPA’s Guidance for 

Implementing the January 2001 Methylmercury Criterion.”74

 

72 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. EPA822-B-00-004. page 4-25. Available at: http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 73 EPA. January 2001. Water Quality Criterion for the Protection of Human Health: Methylmercury. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA 823-R-01-001. pages 21-22. Available 

at: http://www.epa.gov/waterscience/criteria/methylmercury/document.html 74 ODEQ. May 24, 2011. Human Health Criteria Issue Paper. Oregon Department of Environmental Quality. page 

26. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/HumanHealthToxicCriteriaIssuePaper.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

38

3. EPA Action and Rationale Regarding Oregon’s Methylmercury 

Criterion

EPA Action

In accordance with its Clean Water Act authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, 

EPA approves Oregon’s new human health criterion for methylmercury, consistent with EPA’s 

current CWA § 304(a) criteria recommendations, because it is protective of Oregon’s fishing and 

water supply uses. EPA is also approving the first sentence of footnote J which states: This value 

is expressed as the fish tissue concentration of methylmercury. 

EPA Rationale 

EPA’s WQS regulations require that criteria protect the designated uses. As noted previously, 

Oregon’s human health criteria apply to waters with fishing and water supply uses and thus must 

be established at a level that will protect those uses. Therefore, EPA must evaluate whether the 

criteria protect Oregon’s human health uses. 

EPA’s 2000 Human Health Methodology and 2001 Criteria Recommendations for 

Methylmercury provide guidance for deriving human health criteria for methylmercury. For 

each variable used in the criteria calculation, EPA provides a “national default value” and 

guidance on specific adjustments that may be necessary to reflect local conditions and/or protect 

identifiable subpopulations. As part of evaluating whether Oregon’s criteria protect the 

designated uses, EPA reviewed the input values used by Oregon and whether there was Oregonspecific information relative to each value that should be considered in the review. 

For all input variables except for the fish consumption rate and the RSC value, Oregon used 

EPA’s recommended 304(a) national default values for calculating the methylmercury criterion. 

EPA has not identified any local or regional data to indicate that the national values for the 

reference dose, body weight, or drinking water intake rate are inappropriate for use in Oregon. 

Oregon has used local and regional data to develop the fish consumption rate and RSC values 

used to calculate the methylmercury criterion. EPA has reviewed the information used in 

developing these values and has found that ODEQ appropriately considered the available data 

and developed input values consistent with EPA guidance. 

EPA’s 2001 Methylmercury Criteria document provides an extensive technical basis and 

justification as to how EPA’s recommended criterion adequately protects human health uses. 

Based on Oregon’s consistency with EPA’s recommendations in the 2001 Methylmercury 

Criteria document and as discussed above, EPA has determined that Oregon’s new 

methylmercury criterion protects human health uses in accordance with 40 C.F.R. Part 

131.11(a)(1). 

In addition, EPA is approving the first sentence of footnote J which states: This value is 

expressed as the fish tissue concentration of methylmercury. This sentence of the footnote 

provides clarification that the human health criterion for methylmercury is expressed as a fish 

tissue concentration rather than as a water column concentration. Oregon’s new footnote 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

39

language along with the human health criterion value for methylmercury are consistent with 

EPA’s recommended 304(a) national default values for calculating the criterion. This sentence 

of the footnote establishes a legally binding requirement under state law and helps describe a 

desired ambient condition of a waterbody to support a particular designated use and is therefore 

considered a WQS subject to EPA review and approval under 303(c) of the CWA. The 

description of the applicable expression of methylmercury is a component of the overall level of 

protection afforded by the criterion. Since this sentence of the footnote specifies the applicable 

expression of the methylmercury criterion Oregon adopted, EPA has approved this sentence of 

the footnote as a WQS. 

EPA acknowledges the second sentence of footnote J which states: Contaminated fish and 

shellfish is the primary human route of exposure to methylmercury. This sentence of the 

footnote provides details on the primary route of human exposure to methylmercury, but does 

not establish a legally binding requirement under State law and it does not describe a desired 

ambient condition of a waterbody to support a particulate designated use. For this reason, this 

sentence of footnote J is not considered a WQS subject to EPA review and approval under 303(c) 

of the CWA. As a result, EPA is taking no action to approve or disapprove the second sentence 

of footnote J for methylmercury.

E. INORGANIC ARSENIC CRITERIA

1. Background

The Oregon Environmental Quality Commission directed ODEQ to revise Oregon’s human 

health criteria for toxic pollutants based on an increased fish consumption rate of 175 grams per 

day as well as to carefully consider cost effective and environmentally meaningful 

implementation of the criteria and review the data and science behind the criteria for earth 

metals.75 ODEQ reviewed the science supporting the EPA’s recommended 304(a) arsenic 

criteria and considered the appropriateness of revising the criteria to more closely reflect the 

levels of arsenic that naturally occur in Oregon waters. Oregon’s revised arsenic criteria, 

submitted to EPA on July 12, 2011 are the result of that review. Oregon’s goal in reevaluating 

the criteria was to protect human health, reduce toxic pollutants and to achieve meaningful 

environmental results commensurate with the cost.76 

Oregon made the following arsenic-related regulatory revisions (including some changes other 

than revisions to arsenic criteria): 

 

75 Oregon Environmental Quality Commission (OEQC). October 23, 2008. Oregon Environmental Quality 

Commission Minutes of the Three Hundred and Forty-sixth Meeting. Available at: 

http://www.deq.state.or.us/about/eqc/minutes/2008/2008octEQCMinutes.htm 76 ODEQ. April 5, 2011. Memo from Dick Pedersen, Director ODEQ, to the Environmental Quality Commission. 

Agenda Item E. Rule adoption: Amending water quality standards for arsenic, April 21-22, 2011EQC meeting. 

Oregon Department of Environmental Quality. pages 1-2. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/EQCItemEStaffReport.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

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• Revised the numeric criteria human health criteria for arsenic in OAR 340-04-0033 Table 

20.

• Identified the form of arsenic addressed by the criteria as inorganic arsenic.

• Added footnote A which states “The arsenic criteria are expressed as total inorganic 

arsenic. The ‘organism only’ criteria are based on a risk level of approximately 1.1 x 

10-5, and the ‘water + organism’ criterion is based on a risk level of 1.1 x 10-4.”77

• Revised the drinking water M.C.L. from 0.05 mg to 10 μg/l in Table 20 and added 

footnote 1 which states “The arsenic value is shown here for informational purposes only 

and is not a water quality criterion.”

• Added a new provision, OAR 340-04-0033(2)(b), that states the arsenic criteria become 

effective for purposes of State law and the CWA at the time of EPA approval.78

• Added an arsenic reduction policy under State law to address the reduction of arsenic 

from some anthropogenic sources in the vicinity of public drinking water intake 

supplies.79

The revised arsenic criteria were adopted through a public notice and rulemaking action separate 

from that used to adopt the June 16, 2011 human health criteria revisions. This separate 

rulemaking process is described in Section III above. 

ODEQ reviewed the available scientific literature on bioaccumulation of arsenic and the ratio of 

inorganic arsenic to total arsenic in freshwater and marine environments. ODEQ also reviewed 

data specific to waters in Oregon and used the information to derive arsenic criteria for Oregon’s 

waters.

Arsenic is a known carcinogen that may cause cancer in skin or internal organs such as the liver, 

kidneys, lungs and bladder. Other potential health impacts from arsenic include cardiovascular, 

kidney, central nervous system and hyper-pigmentation or keratosis effects.80 In its 304(a) 

criteria recommendations EPA states that arsenic criteria should be based on cancer endpoints 

and be applied as inorganic arsenic. 

Naturally-occurring arsenic in Oregon comes from geologic sources. It is typically present at 

natural levels in fresh surface waters at background levels that range from less than 1 microgram 

per liter (μg/l) to 3 μg/l. ODEQ data indicate that much higher arsenic levels (greater than 5-10 

μg/l) may be present in some south central and southeastern Oregon watersheds but it is not 

known whether these levels represent solely natural geologic sources or are elevated due to 

 

77 Footnote A for arsenic was established in Table 40 in ODEQ’s July 21, 2011 submittal to EPA. 78 This language was deleted as part of ODEQ’s July 21, 2011 submittal to EPA since effective dates of the criteria 

are addressed in OAR 340-041-0033(1), which includes arsenic. 79 To accommodate additional revisions associated with ODEQ’s submittal to EPA on July 21, 2011 ODEQ moved

the location of this rule from OAR 340-041-0033(4) to OAR 340-041-0033(7). However, the rule language was not 

revised.

80 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA-822-B-00-004. page 2-6. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

41

anthropogenic activity.81 ODEQ’s review of the scientific literature indicates natural total 

arsenic levels of the oceans to be in the range of 1 to 3 μg/l.82 

EPA’s current 304(a) human health criteria recommendations for arsenic, published in 1986, are 

derived using a fish consumption rate of 6.5 grams per day and a cancer slope factor of 1.75 and 

are recommended to be applied as inorganic arsenic.83 As is the case for all pollutants, EPA’s 

2000 Human Health Methodology encourages states to use local and regional data when making 

risk management decisions inherent in developing criteria, including decisions inherent in 

selecting the appropriate fish consumption rate, target risk level and bioaccumulation factor.84

2. Numeric Criteria Revisions

 

Based on its review of current data and information, ODEQ found differences in the 

bioconcentration (BCF) of arsenic in freshwater and saltwater organisms. In addition, DEQ 

found the ratio of inorganic arsenic relative to total arsenic differs in the freshwater and marine 

environments. Based on these findings, Oregon adopted two sets of criteria, one applying to 

freshwater and the other to saltwater. The revised criteria and the input variables used to 

calculate the criteria are presented in Tables 9 and 10 below. 

Oregon has adopted the following new criterion for inorganic arsenic: 

Table 9: Oregon’s revised arsenic criteria (as inorganic arsenic).

Pollutant Carcinogen Water + Organism 

(μg/L)

Organism Only (μg/L)

Arsenic (inorganic)A  2.1 2.1 (freshwater)

1.0 (saltwater)

Footnote A: The arsenic criteria are expressed as total inorganic arsenic. The “organism only” criteria 

are based on a risk level of approximately 1.1 x 10-5, and the “water + organism” criterion is based on a 

risk level of 1.1 x 10-4. 

Table 10. Input variables for Oregon’s revised arsenic criteria. 

Water + organism: 

freshwater

Organism only: 

freshwater

Organism only: 

saltwater

Revised Criteria 2.1 μg/l 2.1 μg/l 1.0 μg/l

Input Variables FCR=175 FCR=175 FCR=175

 

81 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. page 6. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf 82 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. page 14. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

83 EPA. May 1, 1986. Quality Criteria for Water. U.S. Environmental Protection Agency, Office of Water. 440/5-

86-001. At: https://owpubauthor.epa.gov/scitech/swguidance/standards/upload/2009_01_13_criteria_goldbook.pdf 84 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA-822-B-00-004. page 2-6. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

42

BCF=14 

IF=10%

CSF=1.5 

Risk level=1x10-4

BCF=14 

IF=10%

CSF=1.5 

Risk level=1.1x10-5

BCF=26 

IF=10%

CSF=1.5 

Risk level=1x10-5

 

FCR = Fish Consumption Rate IF = Inorganic Factor 

 BCF = Bioconcentration Factor CSF = Cancer Slope Factor

Oregon’s arsenic criteria revisions were adopted into Table 20 (Water Quality Criteria 

Summary), OAR 340-04-0033. It should be noted that in Oregon’s June 16, 2011 action, all 

human health criteria in Table 20 were moved to Table 40. Thus, the arsenic criteria are now 

located in Table 40. 

Oregon’s revised numeric criteria for arsenic were derived using the same general methodology 

and equation used to calculate EPA’s current 304(a) criteria for carcinogens. However, based on 

its review of scientific studies and Oregon specific data,85 Oregon applied an inorganic to total 

arsenic ratio in the criteria calculation because the arsenic criteria are expressed in terms of 

inorganic arsenic, but the toxicity data used to develop EPA’s BCF are reported in the form of 

total arsenic. Therefore, Oregon applied the inorganic to organic arsenic ratio to the criteria 

calculated using BCF values they derived based on state-specific data. Oregon also applied a 

fish consumption rate based on state-specific data. Oregon used the cancer slope factor listed in 

EPA’s IRIS database available at the time of criteria adoption (April 2011). The input variables 

used by Oregon to derive their revised criteria are listed in Table 10 above. 

a) Freshwater Criteria

Body weight and drinking water intake rate 

Oregon used EPA’s recommended national default rates for body weight and drinking water 

intake rates. These are the same values that Oregon used to derive all other criteria addressed in 

this action. Further detail on these variables was provided above. 

Fish consumption rate

A fish consumption rate of 175 grams per day was used to derive the freshwater arsenic criteria. 

This is the same fish consumption rate that Oregon used to derive all other criteria addressed in 

this action. As discussed in detail above, this rate was determined by ODEQ to be appropriate 

for use in Oregon’s human health criteria following a thorough review of local and regional data. 

The fish consumption rate of 175 grams per day was selected by Oregon to ensure protection of 

all people in Oregon who may consume fish and shellfish from state waters including those who 

traditionally consume large amounts of fish for subsistence, health, economic or other reasons.86

 

85 For more detail, see previous description in this document of methodology for deriving criteria for carcinogens.

 

It reflects the 95th percentile of tribal members surveyed as part of the CRITFC Survey and the 

86 ODEQ. October 6, 2008. Memo from Dick Pederson, Director ODEQ, to the Environmental Quality 

Commission. Agenda Item G, Action Item: Oregon’s Fish Consumption Rate – For Use in Setting Water Quality 

Standards for Toxic Pollutants October 23, 2008 EQC Meeting. Oregon Department of Environmental Quality. 

page 7. Available at: http://www.deq.state.or.us/about/eqc/agendas/attachments/2008oct/ItemG.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

43

90th percentile of subsistence consumers surveyed in regional fish consumption studies. The 

Human Health Focus Group formed by ODEQ to provide technical recommendations for 

selecting a fish consumption rate appropriate for Oregon found that fish consumers generally eat 

a variety of species that are the most readily available geographically and seasonally and that the 

range of consumption rates among fish consumers tend to be comparable regardless of the 

species that are available at any given time.

87 Thus, Oregon determined the rate of 175 grams 

per day appropriate for protection of high consumers from both freshwater and saltwater 

environments throughout the state. 

Bioconcentration factor 

Limited data are available regarding bioaccumulation (BAF) and bioconcentration (BCF) of 

arsenic in aquatic species. As discussed above, EPA recommends bioaccumulation data be used 

when available in order to take into consideration all pathways of accumulation, not merely the 

concentration that is received from water as reflected in bioconcentration data. EPA review of 

the literature found no relevant BAF data was available and thus EPA recommended that BCF 

data be used by Oregon to determine appropriate BCFs for use in deriving their arsenic criteria.88 

EPA reviewed the available literature that might be relevant to recalculating a BCF specific to 

Oregon’s waters and provided that information to ODEQ.89 Only six published studies were 

identified and only four of the studies were found suitable for use in recalculating a BCF. 

Limitations in the data reported in two of the studies resulted in EPA determining they were not 

appropriate for use and thus were not used in either ODEQ’s recalculations or EPA’s review of 

the recalculated BCFs. The four studies found to be appropriate for this purpose and thus used 

provided data for only three species. One data set is from a test of a saltwater mollusk, the 

eastern oyster, and the others tested two freshwater finfish, bluegill and rainbow trout. 

Additional information on these studies can be found in ODEQ’s April 2011 review document.90

Oregon determined that a BCF of 14 was appropriate for use in developing arsenic human health 

criteria for freshwaters of the state based on their review of the data contained in the above 

mentioned studies. A BCF of 14 represents the geometric mean of the data available from the 

studies of freshwater organisms (two publications on rainbow trout91 and one on bluegill92

 

87 ODEQ. June 2008. Human Health Focus Group Report. Oregon Fish and Shellfish Consumption Rate Project.

Oregon Department of Environmental Quality. pages 18-19. Available at: 

). 

Oregon determined that the BCF data for the eastern oyster, a marine mollusk, was not 

appropriate for use in deriving a freshwater BCF because the oyster was a marine organism and 

available data indicate marine organisms are more likely to bioaccumulate arsenic than 

freshwater organisms. Furthermore, DEQ stated that they were not aware of data showing 

http://www.deq.state.or.us/wq/standards/docs/toxics/HHFGFinalReportJune2008.pdf

88 EPA. November 2011. Oregon Arsenic BCF and 304(a) Calculations. 

89 EPA. November 2011. Oregon Arsenic BCF and 304(a) Calculations. 90 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf 91 McGeachy and Dixon, 1990. Canadian Journal of Fisheries and Aquatic Sciences. 47: 2228-2233; Rankin and 

Dixon, 1994. Canadian Journal of Fisheries and Aquatic Sciences. 51: 372-380. 92 Barrows, et al. 1980. Ann Arbor Science Pub., Inc., Ann Arbor, MI. pages 379-392.
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

44

harvesting or consumption of mollusks or other shellfish from freshwaters in Oregon and thus, 

freshwater mollusks were not likely to comprise a significant portion of the fish consumed from 

freshwaters in Oregon. Thus Oregon assumed finfish would be the primary exposure route for 

arsenic ingested from freshwaters and therefore, used only the data from finfish studies to 

calculate the freshwater BCF.93,94 Based on this evaluation, ODEQ found that a BCF of 14 was 

a reasonable and protective value to use in calculating the arsenic criteria for Oregon’s 

freshwaters. 

Cancer Slope Factor 

Similar to all other criteria addressed in this action, for arsenic, ODEQ used the cancer slope 

factor identified in EPA’s Integrated Risk Information System (IRIS) data base at the time of 

rule adoption (April 2011). For arsenic this value is 1.5 (mg/kg/day)-1 and was last modified in 

1998. 

Inorganic Proportion Factor (Inorganic to Total Arsenic Ratio) 

Arsenic is present in the environment and in fish tissue in both organic and inorganic forms. 

Inorganic arsenic, specifically arsenite (trivalent or As III), is the form that is most toxic to 

humans and used to develop toxicity data for cancer and other end points. Thus, EPA 

recommends that human health criteria for arsenic are developed specific to inorganic arsenic 

and apply to the inorganic portion of arsenic in the water column. The inorganic portion may be 

referred to as either “inorganic arsenic” or “total inorganic arsenic”. When both inorganic and 

organic arsenic are included, it is referred to as “total arsenic”.

95

All of the bioconcentration studies identified by EPA and used by Oregon reported arsenic as 

total arsenic, not inorganic arsenic. In order to address this difference in form and toxicity, 

Oregon multiplied the BCF by an “inorganic proportion factor” that reflects the ratio of inorganic 

to total arsenic likely to be present in the water. The proportion varies geographically and 

between fresh and marine waters so must be determined using state or local data.

Only limited data are available relative to the ratio of inorganic to total arsenic in Oregon’s 

freshwaters. Previous studies have reported the proportion of inorganic arsenic found in fish 

tissue collected in the Columbia and Willamette rivers to contain an average of 6.5% inorganic 

arsenic while the ratios reported for individual species of fish ranged from 0.5% to 9.2% 

inorganic arsenic.96

 

93 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. pages 12-13. Available at: 

 ODEQ also found several other sources of information indicating that an 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf 

ODEQ. March 2011. Summary of Public Comment and Agency Response. Amending Oregon’s Water Quality 

Standards: Revising Human Health Criteria for Arsenic. Oregon Department of Environmental Quality. pages 16-

17. Available at: http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AttCArsenicPublicComment.pdf 94 EPA’s review of this decision is documented later in this subsection.

95 EPA. 2009. EPA National Recommended Water Quality Criteria. U.S. Environmental Protection Agency Office 

of Water. Office of Science and Technology. Available at: 

http://water.epa.gov/scitech/swguidance/standards/current/upload/nrwqc-2009.pdf 96 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. page 13. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

45

inorganic proportion of 10% or less was typical of freshwater environments.97 Based on these 

findings, Oregon determined that an inorganic factor of 10% was a conservative ratio and 

appropriate for use in deriving the arsenic criteria for Oregon’s freshwaters. 

To incorporate the inorganic factor (IF) into the calculation, ODEQ used the following revised 

equations: 

 Water + fish ingestion Criterion (μg/L) = 1000 x RF x BW

 q1*[DW + (BCF x FCR x IF)]

 

 Org Only Criterion (μg/L) = 1000 x RF x BW 

 q1*[BCF x FCR x IF] 

Carcinogenic Risk Level 

In the 2000 Human Health Methodology EPA states that it believes States and authorized Tribes 

have the flexibility to adopt the carcinogenic risk level they find appropriate for protection of the 

designated uses as long as the general population is protected at a 10-5 or 10-6 risk level and 

highly exposed populations are protected at a risk level that does not exceed 10-4.

98 With the 

exception of arsenic, Oregon has used a risk rate of 10-6 when developing water quality criteria 

for carcinogenic pollutants. However, due to the natural levels of arsenic in Oregon’s waters 

and the exposure levels resulting from natural sources of arsenic, Oregon has chosen to use a risk 

level of 10-4 for the arsenic criteria. Oregon made this policy decision following consideration of 

several alternatives and consideration of public comments received on the proposed criteria. The 

lower level of protection afforded by the proposed criteria was clearly identified by ODEQ in the 

documents provided to the public during both public notice periods and in the materials 

presented to the EQC at the time the rule was adopted.

99

 

EPA. 2002. Columbia River Basin Fish Contaminant Survey, 1996-1998. U.S. Environmental Protection Agency, 

Region 10, Seattle, Washington. EPA 910-R-02-006. Available at: 

 ODEQ has stated that they made this 

http://yosemite.epa.gov/r10/oea.nsf/0703bc6b0c5525b088256bdc0076fc44/c3a9164ed269353788256c09005d36b7/

$FILE/Fish%20Study.PDF 

EVS Environmental Consultants. November 21, 2000. Human Health Risk Assessment of Chemical Contaminants 

in Four Fish Species from the Middle Willamette River, Oregon. Prepared for the Oregon Department of 

Environmental Quality, Portland, Oregon. Available at: 

http://www.deq.state.or.us/wq/willamette/docs/studies/hhrarpt.pdf 97ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. page 13. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

98 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, Washington, D.C. EPA-822-B-00-004. page 2-6. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf 99 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

ODEQ. April 5, 2011. Memo from Dick Pedersen, Director ODEQ, to the Environmental Quality Commission. 

Agenda Item E. Rule adoption: Amending water quality standards for arsenic, April 21-22, 2011EQC meeting. 

Oregon Department of Environmental Quality. pages 1-2. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/EQCItemEStaffReport.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

46

decision because of the special circumstances associated with natural levels of arsenic but 

believed that the 10-6 risk level used to derive all other criteria continued to be appropriate.100

In determining the acceptable risk level for the arsenic criteria, ODEQ considered the natural 

background levels of arsenic commonly found in Oregon and evaluated the likely risk associated 

with exposure to these levels for the general population and high fish consumers. As noted 

earlier, ODEQ found that naturally occurring arsenic in many surface waters of the state range

from less than 1 μg/l up to 3 μg/l and may occur at much higher levels. Therefore, ODEQ 

evaluated the risks that would be associated with arsenic criteria of 2-3 μg/l. 

 

Using the input variables identified above, Oregon determined that a freshwater water plus 

organism (water + org) criterion of 2.1μg/l would result in a carcinogenic risk of 1x10-4. Since 

this value would protect high fish consumers of the State (those consuming 175 grams of fish per 

day) at a 10-4 risk level, Oregon found this criterion would protect the human health uses in State 

waters at a level consistent with the risk levels recommended by EPA in the 2000 Human Health 

Methodology.101 Thus, Oregon adopted an arsenic water plus organism criterion of 2.1 μg/l for 

freshwaters.

Oregon similarly evaluated the criterion for protection of waters where fish consumption was a 

designated use but drinking water was not a designated use (organism (org) only criterion). 

Using the same variables discussed above, Oregon determined that a criterion of 19 μg/l would 

protect at a 1x10-4 risk level while a criterion value of 1.9 μg/l would protect at a 1x10-5 risk 

level. Oregon noted that establishing the org only criterion at the same risk level as the water + 

org criterion would result in a criterion that was nearly an order of magnitude less stringent than 

the water + org criterion. Therefore, after reviewing several options Oregon established the 

organism only criterion at the same level as the water + org criterion (2.1 μg/l). Oregon’s 

revised freshwater arsenic org only criterion of 2.1 μg/l represents a carcinogenic risk of 1.1 x 

10-5 to high consumers of the State (at a fish consumption rate of 175 grams/day). Oregon found 

this level of protection appropriate as it was within the risk range identified in EPA’s 2000 

Human Health Methodology and took into consideration the natural levels of arsenic found in 

Oregon’s waters.

102

 

ODEQ. April 21, 2011. Recommended Revisions to Oregon’s Human Health Criteria for Arsenic, Presentation to 

the EQC. See Action Item E audio presentation. Available at: 

 

http://www.deq.state.or.us/about/eqc/minutes/2011/2011aprEQCMinutes.htm 100 ODEQ. March 2011. Summary of Public Comment and Agency Response. Amending Oregon’s Water Quality 

Standards: Revising Human Health Criteria for Arsenic. Oregon Department of Environmental Quality. page 25. 

Available at: http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AttCArsenicPublicComment.pdf

ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. pages 10-11. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

ODEQ. April 5, 2011. Memo from Dick Pedersen, Director ODEQ, to the Environmental Quality Commission. 

Agenda Item E. Rule adoption: Amending water quality standards for arsenic, April 21-22, 2011EQC meeting. 

Oregon Department of Environmental Quality. pages 4-5. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/EQCItemEStaffReport.pdf 101 ODEQ. April 5, 2011. Memo from Dick Pedersen, Director ODEQ, to the Environmental Quality Commission. 

Agenda Item E. Rule adoption: Amending water quality standards for arsenic, April 21-22, 2011EQC meeting. 

Oregon Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/EQCItemEStaffReport.pdf 102 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

47

b) Saltwater Criteria

Oregon’s objectives in developing an arsenic criterion for saltwater was to protect those who 

consume fish and shellfish from Oregon’s marine and estuarine waters to which a criterion 

applies, taking into consideration the presence of naturally occurring levels of arsenic in marine 

waters. Uncertainties in the scientific community’s current knowledge of the various species of 

arsenic in the saltwater environment and in marine and estuarine species also were considered in 

the evaluation.103 

Oregon has not designated any saltwaters of the state as a drinking water use. Consistent with 

this designation, the only human health criterion applicable to and derived for saltwaters in 

Oregon are the organism only criteria (i.e. developed to protect humans from health effects 

incurred while ingesting fish and shellfish). As identified in Table 9 above, Oregon adopted an 

organism only criterion of 1.0 μg/l inorganic arsenic for all saltwaters of the State. The 

following discusses the input variables used and the conclusions reached by ODEQ in 

establishing this criterion. 

Body weight, fish consumption rate and cancer slope factor

The input variables used for body weight, fish consumption rate and the cancer slope factor to 

derive Oregon’s arsenic human health water quality criteria applicable to saltwater are the same 

as those used to derive the freshwater criteria discussed above. 

Bioconcentration factor and inorganic proportion factor 

Oregon’s arsenic criterion for saltwater was calculated using a BCF of 26 (the geometric mean of 

all BCFs for fresh and saltwater species combined) and an inorganic proportion factor of 10%. 

As discussed in the freshwater section above, bioconcentration data for arsenic is limited. EPA’s 

review of the literature found only four studies appropriate for use in calculating BCFs and only 

one of those tested an organism from a saltwater environment (eastern oyster).104

 Department of Environmental Quality. page 14. Available at: 

 When ODEQ 

reviewed the available studies, they found a large difference in BCF values found in the study of 

the Eastern oyster (BCF of 350) relative to those found in the freshwater finfish studies (BCFs of 

4 to 27). Given the differences in the BCFs and recognizing that people consume both mollusks 

and finfish from the Oregon waters where this criterion would apply, ODEQ evaluated potential 

options for criteria using two scenarios (see Table 11 below). The first scenario considered 

criterion calculated using a BCF of 26, the geometric mean of all available BCF data (both 

saltwater and freshwater). The second evaluated options using a BCF of 350, the geometric 

mean from the one study of a saltwater organism. Under both scenarios, the criteria that would 

result from using inorganic proportion factors of 1% and 10% were calculated. Results of the 

various options were compared to levels of arsenic naturally present in estuarine and marine 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf 103 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. page 14. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

104 Zaroogian and Hoffman. 1982. Arsenic uptake and loss in the American oyster, Crassostrea virinica.

Environmental Monitoring and Assessment 1:345-358.
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

48

waters. Following analysis of the options generated under the two scenarios ODEQ evaluated 

the level of protection provided by each and compared the criteria to the concentrations of 

arsenic naturally present in estuarine and marine waters. Based on this analysis ODEQ 

determined that a criterion of 1.0 μg/L inorganic arsenic was appropriate for protection of the 

fish consumption use in Oregon’s saltwaters. 

Table 11. Scenarios evaluated by Oregon and/or EPA. 

Scenario A B C D E F

Fish Consumption 175 g/day 175 g/day 175 g/day 175 g/day 175 g/day

Bioconcentration 26 26 350 350 350

Inorganic portion 10% 1% 1% 10% 7.3%

Risk level 1 x 10-5 1x10-6 1 x 10-5 1.3 x 10-5 9.6 x 10-5

Natural ocean level 1 – 1.2 μg/l

Resultant Criterion 1.0 μg/l 1.0 μg/l 0.8 μg/l 1.0 μg/l 1.0 μg/l 1.0 μg/l

As part of this evaluation, ODEQ evaluated the appropriate species to be considered in deriving a 

BCF value, the ratio of inorganic to total arsenic in the ocean environment, and the natural level 

of arsenic in Oregon’s salt waters. When evaluating BCF data, ODEQ found that 

bioconcentration of arsenic in the tissue of invertebrates tended to be higher than that for 

vertebrates. In particular, they found that crustaceans and mollusks tended to accumulate more 

inorganic arsenic in their tissue (the form toxic to humans) than anadromous or marine fish. 

While data specific to consumption levels of various species from Oregon’s saltwaters was not 

available, ODEQ knew that both shellfish and finfish were harvested and consumed from 

saltwaters in Oregon. ODEQ’s literature review also indicated that, for the general US 

population, estuarine and marine mollusks represent only a small percent (3-13%) of the total 

fish and shellfish consumption. Given the small percentage of shellfish consumption relative to 

fish consumption and the much higher bioconcentration rate in shellfish, ODEQ concluded that a 

criterion calculated using only the oyster data (BCF = 350) was likely to be overly 

conservative.105 

Oregon’s literature review found a growing body of literature indicating that while saltwater 

organisms may contain more total arsenic than freshwater fish, the predominant form of arsenic 

in marine species is organic arsenic (i.e. rather than inorganic arsenic).106 One analysis of five 

types of ocean finfish and ocean shrimp found that inorganic arsenic in the organism’s tissues 

was less than 0.1% of the total arsenic present in tissues.107 Other literature reported values of 

less than 3% and more recent surveys report values less than 1%.108

 

105 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. pages 15-16. Available at: 

 A summary of the data from

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

106 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. pages 16-17 in EPA 2003; Neff 1997; Schoof and Yager 2007; Tanaka and 

Santosa 1995; TetraTech 1996, IN EPA 2002; and Williams et.al. 2006. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf 107ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. pages 16-17 in Schoof et. al., 1999 in BorakandHosgood. 2007. Available 

at: http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf 108 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

49

20 studies is provided below and indicates that the inorganic arsenic in tissues of marine fish and 

marine shellfish ranged from 0.0001% to 7.3% of the total arsenic present; anadromous fish 

ranged from 0.3% to 3.04% and freshwater fish tissue contained between 0.5% and 26.6% 

inorganic arsenic.

109

Inorganic arsenic as a % of total arsenic in seafood measured as ng/g wet weight

 Mean Range 

 Freshwater 7.2 0.5-26.6 

 Anadromous fish 1.1 0.03-3.04 

 Marine fish 1.0 0.001-6.9 

 Marine Crustaceans 1.3 0.001-7.3 

 Marine Mollusks 1.8 0.04-6.5 

Based on the review of the above information, ODEQ concluded it appropriate to use an 

inorganic factor of 1% if used in association with a conservative BCF of 350. However, if using 

the less conservative BCF of 26, ODEQ used a more conservative inorganic factor of 10% in 

their initial scenarios. ODEQ found comparison of these scenarios was a reasonable approach 

to take into account the variability and uncertainty in both the BCFs and inorganic factors while 

not resulting in an overly conservative criterion.110 

Natural ocean levels and complexities in the marine environment 

Oregon’s review of the literature found natural total arsenic levels of oceans waters to be in the 

range of 1 to 3 μg/l. Data cited from the Pacific Ocean indicated average concentrations of 1.1 – 

1.2 μg/l.111 

Oregon did not have any data from Oregon’s marine waters where inorganic and total arsenic 

were measured simultaneously. Thus, they relied on the above literature for their conclusion that 

the natural concentrations of arsenic in Oregon salt waters contain 1.0 μg/l or more of inorganic 

arsenic and that a waterbody criterion of 1.0 μg/l should not present any greater human health 

risk than that naturally present.112

 

Department of Environmental Quality. pages 16-17 in Borak and Hosgood, 2007; EPA 2003; Neff, 1997. Available 

at: http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

109 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. pages 16-17 in Schoof and Yager, 2007. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

110 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf 111 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. pages 15-16 in Tanaka, Shigeru and Sri Juari Santosa. 1995. The 

concentration distribution and chemical form of arsenic compounds in sea water. Biogeochemical Processes and 

Ocean Flux in the Western Pacific, Eds. H. Sakai and Y. Nozake, page. 1590170. Terra Scientific Publishing 

Company, Tokyo. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

112 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. page 15. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

50

Carcinogenic Risk Level 

For the saltwater organism only criterion of 1.0 μg/l inorganic arsenic represents a carcinogenic 

risk level of 10-5. Since this value would protect high fish consumers of the State (those 

consuming 175 grams of fish per day) at a 10-5 risk level, Oregon found this criterion would 

protect the human health uses in State waters at a level consistent with the risk levels 

recommended by EPA in the 2000 Human Health Methodology.113 Furthermore, ODEQ 

determined it was appropriate to use a different carcinogenic risk level for this criterion than that 

used for other criteria in the state (10-6) since the resultant criterion concentration reflected that 

which naturally occurred in marine waters.

114 (See the discussion regarding carcinogenic risk 

level for the freshwater arsenic criteria for more detail regarding EPA’s 2000 Human Health 

Methodology.) 

Based on the above findings, Oregon considered the scenarios in Table 11 above when selecting 

an appropriate org only criterion for arsenic in Oregon’s saltwaters. Based on the conservative 

nature of a BCF of 350, the variability in the data, the uncertainties in the scientific communities 

current knowledge and ODEQ’s determination that “there does not appear that an unacceptable 

human health risk with eating fish from an unpolluted marine environment,” Oregon revised the 

saltwater criterion for inorganic arsenic to 1.0 μg/l. 

c) EPA Review of Oregon’s Revised Arsenic Criteria

EPA has reviewed the information provided by Oregon regarding the literature considered during 

their review of the arsenic criteria. EPA determined that Oregon’s review considered the 

relevant and available information relative to selecting appropriate input variables for deriving 

the arsenic criteria. EPA conducted a more detailed review of several of the variables used in 

deriving the criteria. This review is presented below. 

(1) FRESHWATER CRITERIA

BCF for Freshwater Criteria 

EPA has reviewed the literature used by Oregon to calculate a BCF and finds that all relevant 

studies were identified. The use of a geometric mean value from available studies is appropriate 

for deriving a single BCF value. As determined by Oregon, a BCF of 14 is representative of the 

available BCF data relative to freshwater species.

In EPA’s review of the literature relative to bioaccumulation of arsenic in aquatic organisms, no 

BAF studies specific to bioaccumulation in Oregon or models which could readily produce 

 

113 ODEQ. April 5, 2011. Memo from Dick Pedersen, Director ODEQ, to the Environmental Quality Commission. 

Agenda Item E. Rule adoption: Amending water quality standards for arsenic, April 21-22, 2011EQC meeting. 

Oregon Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/EQCItemEStaffReport.pdf

114 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. pages 15-16 in Tanaka and Santosa. 1995 National Academy of Sciences, 

1972 and EPA. 2003. Available at:

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf
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bioaccumulation factors specific to Oregon’s waters were found. Thus, ODEQ’s use of a 

bioconcentration factor is appropriate in this situation. 

In selecting the appropriate BCF for use in deriving freshwater criteria, Oregon reviewed the 

available data for both saltwater and freshwater organisms and considered whether that data was 

representative of organisms likely to be consumed from waters to which the criteria would apply. 

In evaluating the use of the data from a study of the eastern oyster, a saltwater mollusk, Oregon 

noted that saltwater mollusks are not present in freshwaters of Oregon and that they were “not 

aware of any mollusks or other shellfish harvested and consumed from Oregon’s freshwaters”.115 

In order to verify this assertion, EPA consulted the Oregon Department of Fish and Wildlife 

website.116 According to the regulations posted on this site, Oregon prohibits the harvest or 

possession of all freshwater mussels or clams (except for Zebra mussels or Asian clams) except 

as authorized by a Scientific Take Permit.117

While including BCF data from the eastern oyster in the calculations would have expanded the 

scope of represented species to include mollusks, it would have also contributed BCF data from a 

marine species into the calculation of freshwater criteria. EPA concludes that Oregon’s decision 

not to include the BCF data from the eastern oyster was appropriate, in light of the above data 

with respect to the low likelihood of human consumption of freshwater mollusks in Oregon.

 Furthermore, EPA noted that no freshwater 

mussels or shellfish were included in the species identified in the CRITFC Fish Consumption 

Study. While this later fact does not speak to all mussels or shellfish from freshwaters of 

Oregon, it is one indication that traditional and cultural consumption of these organisms is not 

occurring in a large portion of Oregon. Based on this information, EPA finds the assumption 

made by Oregon as to type of organisms consumed from Oregon’s freshwaters to be reasonable. 

One commenter provided numerous comments relative to the use of a BCF instead of a sitespecific BAF. In the 2000 Human Health Methodology EPA recommends using a BAF in cases 

where data are available. EPA’s review of the literature indicates that data and models are not 

currently available to develop a state-specific BAF for waters in Oregon. Additional information 

on this topic can be found in the above description of the methodology used to develop criteria 

for noncarcinogens and in EPA’s Response to Comments document developed in association 

with the recent June 1, 2010 action on Oregon’s human health criteria adopted in 2004.118

The same commenter noted that recent studies of arsenic bioaccumulation indicate use of a 

regression approach to developing arsenic criteria may be more appropriate than using a single 

criterion applicable to all waters. EPA reviewed the cited study and agrees that it is an approach 

that has been applied on a site-specific basis and could be applied by a state in developing 

criteria for arsenic. However, EPA has not developed a recommended approach for 

 

 

115 ODEQ. April 4, 2011. Issue Paper: Water Quality Standards Review and Recommendations: Arsenic. Oregon 

Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AppEArsenicIssuePaper.pdf

116 Oregon Department of Fish and Wildlife (ODFW). Oregon Wildlife Species: Sport Fish Species of Oregon.

Available at: www.dfw.state.or.us/species/fish/index.asp 117 Oregon Department of Fish and Wildlife (ODFW). 2011 Sport Fishing Regulations. Available at: 

http://www.dfw.state.or.us/fish/docs/2011_Oregon_Fish_Regs.pdf 118 EPA. June 1, 2010. Supplemental Response to Comments Submitted by Northwest Environmental Advocates 

(NWEA) as They Pertain to Oregon’s New and Revised Human Health Water Quality Criteria for Toxics Submitted 

on July 8, 2004.
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incorporating this approach into a water quality criterion and no state has used it to develop a 

water quality criterion. Utilization of a regression approach would result in a criterion expressed 

as an equation for calculating a criterion concentration which varies with the ambient level of 

arsenic present in a waterbody in order to take into account the fact that the fraction of total 

arsenic that is inorganic arsenic tends to decrease as the concentration in the tissues increase. 

Additional questions regarding whether the criteria would more appropriately be expressed as a 

water column or tissue concentration would also need to be addressed. While utilizing this 

approach to developing a state-wide criterion would result in a site-specific criterion that may 

more accurately reflect the desired level of protection at any particular site (i.e. a 10-5 risk level), 

it would not necessarily provide for a greater level of protection. Given that this level of detail is 

not needed to protect the use and that this method has never been applied to derive a water 

quality criterion, EPA finds that it was reasonable for Oregon to establish a single criterion 

concentration and not use this new approach in this rule revision. 

Inorganic Proportion Factor for Freshwater Criteria 

EPA’s review of available information finds that an inorganic proportion factor of 10% 

represents a reasonable and conservative estimate of the proportion of total arsenic present in an 

inorganic form in the tissue of organisms collected from freshwaters in Oregon. EPA notes that 

this same value was used by EPA when conducting site-specific risk assessments in the 

Columbia and Willamette Rivers that considered the same data set. No additional data have

become available since the EPA assessments.

Level of Protection Provided by the Freshwater Criteria

Oregon’s arsenic criteria for fresh waters are established at a level that protect high fish 

consumers in Oregon at carcinogenic risks levels of between 1 x 10-4 to 1 x 10-5 (see more 

detailed discussion above). EPA’s 2000 Human Health Methodology states that states have the 

flexibility to choose an appropriate risk level for use in deriving water quality criteria as long as 

it protects the use to the levels recommended by EPA. Those risk levels are a 10-5 or 10-6 risk 

level for the general population and a risk level that does not exceed 10-4 for highly exposed 

populations. 

Oregon’s criteria were established using a fish consumption rate of 175 grams per day, reflective 

of the 95th percentile of consumption in a high-consuming subpopulation in Oregon and the 90th

percentile of data from regional surveys of high consuming subpopulations. Therefore, the 

criteria represent the level of exposure expected to occur in highly exposed populations of 

Oregon. As such, Oregon’s freshwater arsenic criteria protect highly exposed populations of 

Oregon at a level consistent with EPA’s recommendations (does not exceed 10-4 risk level).

EPA has recommended using a fish consumption rate for the general US population of 17.5 

grams per day if no local or regional data is available. There is currently no available fish 

consumption data specific to the general population of Oregon. If one were to evaluate the 

protectiveness of Oregon’s arsenic criteria at EPA’s default fish consumption rate of 17.5 grams 

per day, the result would indicate a carcinogenic risk level between 1x10-6 and 1x10-5. This risk 

level is consistent with that recommended by EPA. Therefore, EPA finds that ODEQ’s revised 

arsenic criteria for freshwater are established at a level protective of both the general population 

and high fish consuming populations consistent with the levels recommended by EPA in the 
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2000 Human Health Methodology. 

(2) SALTWATER CRITERIA

BCF for Saltwater Criteria 

EPA has reviewed the literature used by Oregon to calculate the BCF used to derive the saltwater 

criterion and finds that all relevant studies were identified. EPA also found the use of a 

geometric mean value to be appropriate for deriving a BCF. As considered by Oregon, a BCF of 

26 is representative of all available BCF data for both saltwater and freshwater species (one 

study of a saltwater mollusk and three studies of freshwater finfish). A BCF of 350 reflects all of 

the available BCF data for saltwater species (one study of a saltwater mollusk). Oregon 

considered both of these BCF values when evaluating the protectiveness of the revised criterion. 

As noted by Oregon, there is relatively little BCF data available for arsenic and only one study 

that addresses saltwater species. Given the limited data and the differences in BCF between the 

finfish and mollusk data, EPA finds Oregon’s approach of comparing the outcomes of scenarios 

for both a BCF of 26 and a BCF of 350 in terms of protectiveness to be reasonable. (See Table 

11 above). Given the limited data and the variability in the available data, EPA believes that 

evaluating the level of protection provided by a range of inorganic proportion factors in 

association with the different BCF values is also appropriate. EPA’s evaluation of whether the 

criteria derived using these input values is protective of the use is provided below. 

Inorganic Proportion Factor for Saltwater Criterion 

EPA’s review of the literature relative to the ratio of inorganic to total arsenic in the tissue of 

saltwater organisms indicated that ODEQ reviewed the available information on this subject. 

EPA concurs that the information is limited, especially specific to Oregon waters, but it does 

indicate that the ratio of inorganic to total arsenic in tissues of saltwater organisms is typically 

lower than that found in freshwater organisms. Thus, using the 10% inorganic ratio that is also 

used in the freshwater criteria serves to provide a conservative estimate of the ratio—i.e., one 

that is larger than the mean ratio values found in various studies (1 to 3%). Given the variability 

in these factors and in the BCF values discussed above, EPA believes it was appropriate for 

ODEQ to have considered several different exposure scenarios when developing this criterion 

and that ODEQ’s use of inorganic factors of 10% and 1% in the scenarios was also reasonable. 

EPA’s evaluation of whether the criteria derived using these input values is protective of the use 

is provided below. 

Level of Protection Provided by the Saltwater Criteria

Oregon adopted a saltwater criterion of 1 μg/l and relied on multiple lines of evidence in 

determining it is protective of Oregon’s human health uses. Consistent with Oregon’s approach 

at evaluating scenarios, EPA has evaluated the level of protection provided by each scenario 

presented. As illustrated in Table 11 above, when the more conservative BCF (350) was paired 

with the less conservative inorganic proportion factor (1%), a criterion of 1.0 μg/L was found to 

protect high fish consuming populations (175 g/day) at a 1.3 x 10-5 risk level. When the less 

conservative BCF (26) was paired with the more conservative inorganic proportion factor (10%), 

a criterion of 1.0 μg/l was found to protect high consumers (175 g/day) at a 1.0 x 10-5 risk level. 

Both of these scenarios provide a level of protection consistent with that recommended by EPA 
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in the 2000 Human Health Methodology. However, when EPA evaluated the level of protection 

that would be provided using the more conservative of both factors (BCF of 350 and inorganic 

proportion factor of 10%), a criterion of 1.0 μg/l resulted in a 1.3 x 10-4 risk level. This level is a 

higher risk than that recommended by EPA in the 2000 Human Health Methodology. EPA notes 

that the highest ratio of inorganic to total arsenic in fish tissue of saltwater organisms identified 

by ODEQ was 7.3%. ODEQ used 10% as a conservative inorganic proportion value for marine 

criteria (incorporating data from freshwater species) but EPA believes 7.3% is also a 

conservative estimate for marine organisms as it is the highest data value reported. Combining 

an inorganic factor of 7.3% (not as conservative a value as selected by Oregon but still 

sufficiently conservative based on a reasonable assessment of the available data) with a BCF of 

350 (more conservative than the value ultimately selected by Oregon), EPA calculated that a 

criterion of 1.0 μg/L would protect high fish consuming populations at a risk level of 9.6 x 10-5. 

Thus, a criterion of 1.0 μg/l calculated using a conservative inorganic proportion factor of 7.3% 

would protect high fish consumers in Oregon at a level consistent with that recommended by 

EPA in the 2000 Human Health methodology. 

Oregon has presented a reasonable scientific basis to not rely solely on the BCF from the eastern 

oyster (350) in calculating the saltwater criterion, and instead rely on a BCF that incorporates 

data from other species (26).119

(3) GENERAL CONSIDERATIONS

 Furthermore, the percentage of total arsenic that occurs in an 

inorganic form that Oregon paired with this BCF (10%) was more than sufficiently conservative 

based on the available data. Based on the calculations discussed in the paragraph above and 

these additional considerations, EPA believes that Oregon’s saltwater criterion for arsenic will 

protect human health consistent with the level recommended by EPA. 

Risk level applied to arsenic criteria relative to that applied to other criteria

EPA reviewed the information provided by Oregon related to establishing criteria for arsenic at a 

level different than that used for all other criteria in the State. EPA notes that ODEQ stated that 

they were addressing arsenic as a special case and clearly stated their reasons for evaluating risk 

management decisions relative to this pollutant. The public notice, memorandum presenting 

recommendations to the EQC and ODEQ’s document presenting its review and 

recommendations for the arsenic criteria all clearly identify that the criteria recommendations 

were established at a level providing less protection than for other pollutants in Oregon. Thus, 

the Commission was made aware of the policy decision inherent in their decision to adopt the 

recommended criteria. Thus, EPA finds that Oregon was reasonably exercising its discretion 

when establishing an alternate risk level for the arsenic criteria.

Cancer Slope Factor 

One commenter noted that a cancer slope factor of 1.75(mg/kg/day)-1 was used by EPA to 

develop the current 304(a) criteria recommendation while another stated that EPA was currently 

 

119 Mollusks tend to accumulate arsenic to a greater extent than other species and mollusks represent only a small 

percent (3-13%) of the U.S. general population’s total fish and shellfish consumption. A marine BCF that is only 

based on mollusk data is therefore not ideally representative of marine species overall. EPA concludes that it was 

reasonable for Oregon to incorporate data from non-mollusk species to arrive at a more representative BCF, even 

though those non-mollusk species were not marine species.
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reviewing the science behind the cancer slope factor. Both of these assertions are correct. 

EPA’s 304(a) criteria recommendations for arsenic were first published in 1986 and uses a 

cancer slope factor of 1.75(mg/kg/day)-1. This recommendation has not been updated to reflect 

the latest value identified in the IRIS database, in part because the science behind that number is 

currently under review. A draft document was circulated for public comment and peer review by 

the Science Advisory Board in 2010.120 EPA is currently reviewing these comments and has yet 

to make a final determination on potential revisions to the cancer slope factor for arsenic. Thus, 

EPA does not believe it appropriate for ODEQ to use the draft value in revising these criteria. 

EPA expects to coordinate with ODEQ regarding the potential need for reevaluation of the 

criteria if a new value is established in IRIS and/or changes are made to EPA’s 304(a) criteria 

recommendations for arsenic.

3. EPA Action and Rationale Regarding Oregon’s Arsenic Criteria

EPA Action

In accordance with its Clean Water Act authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, 

EPA approves Oregon’s revised human health toxic criteria for inorganic arsenic because they 

are protective of Oregon’s fishing and water supply uses. EPA is also approving footnote A 

which states: The arsenic criteria are expressed as total inorganic arsenic. The “organism 

only” criteria are based on a risk level of approximately 1.1 x 10-5, and the “water + organism” 

criterion is based on a risk level of 1.1 x 10-4.

EPA Rationale

EPA’s WQS regulations require that criteria protect the designated uses. As noted previously, 

Oregon’s human health criteria apply to waters with fishing and water supply uses and thus must 

be established at a level that will protect those uses. Therefore, EPA must evaluate whether the 

criteria protect Oregon’s human health uses. 

As discussed in detail above, EPA has found that Oregon considered the available and relevant 

literature in revising Oregon’s arsenic criteria. Oregon provided a reasonable basis for the 

decisions made in developing the criteria. All three of the criteria adopted by ODEQ were found 

to protect human health uses consistent with recommendations provided in EPA’s 2000 Human 

Health Methodology. 

Inorganic Arsenic and Footnote A in Table 40 

EPA’s current 304(a) human health criteria recommendations are specifically identified as 

criteria for inorganic arsenic. As noted above, inorganic arsenic is the form most toxic to 

humans. As such, EPA’s recommendations relative to this criteria and the associated risk 

assessment input variables are expressed as inorganic arsenic. In this revision, Oregon 

specifically identified that the criteria as inorganic arsenic in Table 40 by placing the word 

“inorganic” in parentheses. 

 

120 February 19, 2010. Federal Register, Volume: 75, No.: 33, page: 7477 (78 FR 7477). Available at:

http://www.gpo.gov/fdsys/pkg/FR-2010-02-19/pdf/FR-2010-02-19.pdf 
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In addition, EPA is approving footnote A to the arsenic criteria in Table 40 which states: The 

arsenic criteria are expressed as total inorganic arsenic. The “organism only” criteria are 

based on a risk level of approximately 1.1 x 10-5, and the “water + organism” criterion is based 

on a risk level of 1.1 x 10-4. 

The first sentence of the footnote provides clarification that the human health criterion for 

arsenic is expressed as total inorganic. This new footnote language for arsenic is consistent with 

EPA’s recommended 304(a) national default expression for the arsenic criterion. The second 

sentence of the footnote clearly articulates the input variables regarding risk levels that were used 

to derive the arsenic criteria. This footnote establishes a legally binding requirement under State 

law and helps describe a desired ambient condition of a waterbody to support a particular 

designated use and is therefore considered a WQS subject to EPA review and approval under 

303(c) of the CWA. The description of the applicable expression of arsenic associated risk level

is a component of the overall level of protection afforded by the arsenic criteria. Therefore, EPA 

approves this footnote as a WQS. 

Acknowledgement of Maximum Contaminant Level (MCL) in Table 20

ODEQ revised the drinking water MCL for arsenic from 0.05 mg to 10 μg/l in Table 20 and 

added footnote 1 which states: The arsenic value is shown here for informational purposes only 

and is not a water quality criterion.

Drinking water standards are regulations that EPA sets to control the level of contaminants in the 

nation's drinking water. In most cases, the standard is a MCL, the maximum permissible level of 

a contaminant in water which is delivered to any user of a public water system. The Safe 

Drinking Water Act gives individual states and tribes the opportunity to set and enforce their 

own drinking water standards if the standards are at least as stringent as EPA's national 

standards. When making a determination to regulate, the Safe Drinking Water Act requires 

consideration of these three criteria: 

• the potential adverse effects of the contaminant on the health of humans; 

• the frequency and level of contaminant occurrence in public drinking water systems; and 

• whether regulation of the contaminant presents a meaningful opportunity for reducing 

public health risks. 

ODEQ revised their MCL value for arsenic from 0.05 mg to 10 μg/l in Table 20. This revision 

reflects the current level set under the Safe Drinking Water Act and is consistent with EPA 

recommended drinking water MCL.121 ODEQ also added a clarifying footnote which explains 

that the MCL value is not a water quality criterion.

 

121 January 22, 2001. Federal Register, Volume: 66, No.: 14, page: 6976 (66 FR 6976). Arsenic and Clarifications to 

Compliance and New Source Contaminants Monitoring Final Rule. Available at: http://www.epa.gov/fedrgstr/EPAWATER/2001/January/Day-22/w1668.htm 

March 25, 2003. Federal Register, Volume: 68, No.: 57, page: 14501 (68 FR 14501). Minor Clarification of 

National Primary Drinking Water Regulation for Arsenic; Final Rule. Available at: 

http://www.gpo.gov/fdsys/pkg/FR-2003-03-25/html/03-7048.htm
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Since Oregon has not adopted the arsenic MCL value as a water quality criterion, is not 

considered WQS under the CWA. Instead, the MCL is a value that the State uses to set the 

maximum permissible level of arsenic in drinking water delivered to the tap (after treatment) 

consistent with the Safe Drinking Water Act, not a value that surface waters of the State must 

meet. MCLs are enforceable standards under the Safe Drinking Water Act, and are not required 

under the Clean Water Act unless determined by the State to be needed to protect the designated 

uses. For these reasons, EPA is taking no action to approve or disapprove the revised MCL 

value for arsenic.

Based on the above, EPA has determined that Oregon’s MCL value for arsenic is not a WQS 

subject to EPA review and approval under Section 303(c) of the CWA. As a result, EPA is 

taking no action to approve or disapprove this MCL value. 

Provision Establishing the Effective Date for Arsenic at OAR 340-041-0033(2)(b) 

The following language was added to Oregon’s WQS at OAR340-041-0033 – Toxic Substances 

as part of Oregon’s April 21, 2011 rule revisions submitted to EPA on July 12, 2011:

OAR 340-041-0033(2)(b) The arsenic criteria in Table 20 established by this rule do not 

become applicable for purposes of ORS chapter 468B or the federal Clean Water Act unless and 

until they are approved by EPA pursuant to 40 CFR 131.21 (4/27/2000). 

As part of Oregon’s subsequent June 16, 2011 rule revisions submitted to EPA on July 21, 2011, 

Oregon removed and renumbered the provision cited above language at OAR 340-041-

0033(3)(b) when it reformatted the toxics criteria tables, thus moving the arsenic criteria to Table 

40. Since the deleted language was submitted to EPA as part of the June 16, 2011 rule revisions, 

the provision is no longer applicable under state law and there is no requirement for EPA to act 

on the provision under Section 303(c) of the CWA. 

OAR 340-041-0033(3)(b) The arsenic criteria in Table 20 established by this rule do not become 

applicable for purposes of ORS chapter 468B or the federal Clean Water Act unless and until 

they are approved by EPA pursuant to 40 CFR 131.21 (4/27/2000).

Since ODEQ deleted the language l as part of the July 21, 2011 submittal to EPA, the provision 

is not applicable under State law and there is no requirement for EPA to evaluate the provision 

under Section 303(c) of the CWA. 

In the July 21, 2011 submittal, ODEQ addressed the effective dates of the criteria, including 

arsenic, in the associated revisions at OAR 340-041-0033(1) which describe the dates when the 

toxics criteria in Tables 20, 33A, 33B and 40 become effective under State law and the Clean 

Water Act. EPA’s rationale for approval of OAR 340-041-0033(1) is explained in section V of 

this document. 

Acknowledgement of the Arsenic Reduction Policy at OAR 340-041-0033(7) 

In conjunction with this rule and in recognition that the revised criteria provide a lower level of 

protection than other human health criteria in Oregon, an Arsenic Reduction Policy was adopted 

under State law at OAR 340-041-033(4). To accommodate additional revisions associated with 

the rulemaking submitted to EPA on July 21, ODEQ reorganized the location of the rule and 
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moved the arsenic reduction policy section to OAR 340-041-0033(7). However, ODEQ did not 

revise any of the rule language that was previously adopted. The policy was included in 

Oregon’s WQS regulation in the same section as the arsenic criteria to help ensure it was applied 

where applicable. The policy requires that, in situations where water bodies have background 

levels below the arsenic criteria, dischargers with the potential to affect a drinking water supply 

develop an arsenic reduction plan and take feasible steps to reduce arsenic loading. 

The new policy does not establish a legally binding ambient condition for a waterbody to support 

a particular designated use. Nor does it establish a binding process whereby the State would 

establish an alternate ambient condition for a waterbody following a public process. Rather, this 

policy outlines permitting requirements that the State will place on selected dischargers (those 

located in a surface water drinking water protection area as delineated under the Safe Drinking 

Water Act). These permitting requirements are not tied to what is necessary to protect the 

designated uses of Oregon’s waters, but rather to what measures are “feasible” to reduce arsenic 

loading. The permitting requirements are to be used in association with other implementation 

tools to encourage further arsenic reductions below the established criteria, but they do not 

modify those criteria. 

In the Response to Comments, ODEQ states that the arsenic reduction policy is an important 

component of Oregon’s WQS but that the intent of the policy is not to alter the numeric criteria. 

Furthermore, ODEQ specifies that the policy applies to specific sources and circumstances and 

requires that feasible reduction steps be taken.

122

Based on the above, EPA has determined that this policy is not a WQS subject to EPA review 

and approval under Section 303(c) of the CWA. As a result, EPA is taking no action to approve 

or disapprove this provision. 

 

F. NEW, REVISED AND WITHDRAWN FOOTNOTES 

As part of the July 21, 2011 submittal, ODEQ added, revised and withdrew several footnotes. In 

addition to footnote J (for methylmercury) and footnote A (for arsenic) which are discussed 

separately above with those individual criteria, these changed footnotes are described in further 

detail below.

1. New Footnotes

ODEQ has added new footnotes for the following three pollutants: barium, cyanide, and PCBs. 

Footnote C: Barium

The human health criterion for barium is the same as originally published in the 1976 EPA Red 

Book which predates the 1980 methodology and did not utilize the fish ingestion BCF approach. 

This same criterion value was also published in the 1986 EPA Gold Book. Human health risks 

are primarily from drinking water, therefore no “organism only” criterion was developed. The 

 

122 ODEQ. March 2011. Summary of Public Comment and Agency Response. Amending Oregon’s Water Quality 

Standards: Revising Human Health Criteria for Arsenic. Oregon Department of Environmental Quality. page 26. 

Available at: http://www.deq.state.or.us/wq/standards/docs/toxics/metals/AttCArsenicPublicComment.pdf
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“water + organism” criterion is based on the Maximum Contaminant Level (MCL) established 

under the Safe Drinking Water Act. 

Footnote G: Cyanide

The cyanide criterion is expressed as total cyanide (CN)/L. 

Footnote L: PCBs

This criterion applies to total PCBs (e.g. determined as Aroclors or congeners). 

Acknowledgement of Barium Footnote C 

The new footnote C for barium clarifies the source of information upon which the criterion is 

based. However, the footnote does not establish a legally binding requirement under State law 

nor does it describe a desired ambient condition of a waterbody to support a particular designated 

use. Therefore this footnote is not considered a WQS subject to EPA review and approval under 

303(c) of the CWA. As a result, EPA is taking no action to approve or disapprove the new 

footnote for barium. The underlying criterion for barium was unrevised and therefore EPA is not 

reviewing the underlying criterion as part of this action. 

EPA acknowledges that the footnote provides accurate information respecting the human health 

criterion development for barium. The new footnote for barium explains that the criterion is 

based upon a Safe Drinking Water MCL value along with the rationale for why an “organism 

only” criterion does not exist. The human health criterion for barium was not derived using 

EPA’s 2000 Methodology, but instead was based upon EPA’s national 304(a) criteria 

recommendations in EPA’s 1986 Gold Book. 

EPA Approval of Footnotes for Cyanide (footnote G) and PCBs (footnote L)

In accordance with its Clean Water Act authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, 

EPA approves Oregon’s addition of the two footnotes, Footnote G for cyanide and Footnote L 

for PCBs, as consistent with EPA’s current CWA § 304(a) criteria recommendations.

EPA Rationale Regarding Footnotes for Cyanide (footnote G) and PCBs (footnote L)

Oregon’s new footnote G for cyanide explains that the criterion is expressed as total cyanide 

(CN)/L. EPA has reviewed this footnote language and the 304(a) criteria recommendation, 

which states that the “recommended water quality criterion is expressed as total cyanide, even 

though the IRIS RfD used to derive the criterion is based on free cyanide. The multiple forms of 

cyanide that are present in ambient water have significant differences in toxicity due to their 

differing abilities to liberate the CN-moiety. Some complex cyanides require even more extreme 

conditions than refluxing with sulfuric acid to liberate the CN-moiety. Thus, these complex 

cyanides are expected to have little or no 'bioavailability' to humans. If a substantial fraction of 

the cyanide present in a water body is present in a complex form (e.g., Fe4[Fe(CN)6]3), this 

criterion may be over conservative.”123

 

123 EPA. National Recommend Ambient Water Quality Criteria for the Protection of Aquatic Life and Human 

Health. Published pursuant to section 304(a) of the Clean Water Act. Footnote jj. Available at: 

 Oregon’s new footnote language along with the human 

http://www.epa.gov/waterscience/criteria/wqctable/index.html
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health criterion values for cyanide are consistent with EPA’s recommended 304(a) national 

default values for calculating the criterion. 

This footnote establishes a legally binding requirement under state law and helps describe a 

desired ambient condition of a waterbody to support a particular designated use and is therefore 

considered a WQS subject to EPA review and approval under 303(c) of the CWA. The 

description of the applicable form of cyanide is a component of the overall description of the 

level of protection afforded by the criterion. Since this footnote specifies the applicable form of 

the cyanide criterion Oregon adopted, EPA approves this footnote as a WQS. EPA is approving 

the associated numeric criteria for cyanide as discussed above in section IV.

 

Oregon’s new footnote L for PCBs explains that the criterion applies to total PCBs. EPA has 

reviewed this footnote language and the 304(a) criteria recommendations, which states that the 

“criterion applies to total PCBs, (e.g., the sum of all congener or all isomer or homolog or 

Aroclor analyses.)”124 Oregon’s new footnote language along with the human health criterion 

values for PCBs are consistent with EPA’s recommended 304(a) national default values for 

calculating the criterion. 

This footnote establishes a legally binding requirement under state law and helps describe a 

desired ambient condition of a waterbody to support a particular designated use and is therefore 

considered a WQS subject to EPA review and approval under 303(c) of the CWA. The 

description of the applicable form of PCBs is a component of the overall description of the level 

of protection afforded by the criterion. Since this footnote specifies the applicable form of the

PCB criterion Oregon adopted, EPA approves this footnote as a WQS. EPA is approving the 

associated numeric criteria for PCBs as discussed above in section IV. 

2. Revised Footnotes

ODEQ has revised the footnotes below for the following six pollutants: footnote B: asbestos, 

footnote D: chlorophenoxy herbicide (2,4,5,-TP), footnote E: chlorophenoxy herbicide (2,4,-D), 

footnote F: copper, footnote I: methoxychlor, and footnote K: nitrates.

Table 12: Revised Footnotes. 

Id. Pollutant Previous Footnote New Footnote

B Asbestos Human health criteria for 

carcinogens reported for 

three risk levels. Value 

presented is the 10-6 risk 

level, which means the 

probability of one cancer 

case per million people at 

the stated concentration.

The human health risks from asbestos are 

primarily from drinking water, therefore no 

“organism only” criterion was developed. 

The “water + organism” criterion is based on 

the Maximum Contaminant Level (MCL) 

established under the Safe Drinking Water 

Act.

D Chlorophenoxy 

Herbicide (2,4,5,-TP)

This value is based on a 

Drinking Water regulation. 

The Chlorophenoxy Herbicide (2,4,5,-

TP)criterion is the same as originally 

 

124 EPA. National Recommend Ambient Water Quality Criteria for the Protection of Aquatic Life and Human 

Health. Published pursuant to section 304(a) of the Clean Water Act. Footnote N. Available at: 

http://www.epa.gov/waterscience/criteria/wqctable/index.html
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published in the 1976 EPA Red Book which 

predates the 1980 methodology and did not 

utilize the fish ingestion BCF approach. This 

same criterion value was also published in the 

1986 EPA Gold Book. Human health risks 

are primarily from drinking water, therefore 

no “organism only” criterion was developed. 

The “water + organism” criterion is based on 

the Maximum Contaminant Level (MCL) 

established under the Safe Drinking Water 

Act.

E Chlorophenoxy 

Herbicide (2,4,-D)

This value is based on a 

Drinking Water regulation. 

The Chlorophenoxy Herbicide (2,4,-D) 

criterion is the same as originally published 

in the 1976 EPA Red Book which predates the 

1980 methodology and did not utilize the fish 

ingestion BCF approach. This same criterion 

value was also published in the 1986 EPA 

Gold Book. Human health risks are primarily 

from drinking water, therefore no “organism 

only” criterion was developed. The “water + 

organism” criterion is based on the Maximum 

Contaminant Level (MCL) established under 

the Safe Drinking Water Act. 

F Copper This value is based on a 

Drinking Water regulation.

Human health risks from copper are primarily 

from drinking water, therefore no “organism 

only” criterion was developed. The “water + 

organism” criterion is based on the Maximum 

Contaminant Level (MCL) established under 

the Safe Drinking Water Act.

I Methoxychlor No BCF was available; 

therefore, this value is based 

on that published in the 1986 

EPA Gold Book.

The human health criterion for methoxychlor 

is the same as originally published in the 

1976 EPA Red Book which predates the 1980 

methodology and did not utilize the fish 

ingestion BCF approach. This same criterion 

value was also published in the 1986 EPA 

Gold Book. Human health risks are primarily 

from drinking water, therefore no “organism 

only” criterion was developed. The “water + 

organism” criterion is based on the Maximum 

Contaminant Level (MCL) established under 

the Safe Drinking Water Act.

K Nitrates No BCF was available; 

therefore, this value is based 

on that published in the 1986 

EPA Gold Book.

The human health criterion for nitrates is the 

same as originally published in the 1976 EPA 

Red Book which predates the 1980 

methodology and did not utilize the fish 

ingestion BCF approach. This same criterion 

value was also published in the 1986 EPA 

Gold Book. Human health risks are primarily 

from drinking water, therefore no “organism 

only” criterion was developed. The “water + 
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organism” criterion is based on the Maximum 

Contaminant Level (MCL) established under 

the Safe Drinking Water Act.

EPA Review

All six of these revised footnotes clarify the sources of information upon which the criteria are 

based. The footnotes are not considered water quality standards because they do not establish 

legally binding requirements under State law and do not describe a desired ambient condition of 

a waterbody to support a particular designated use. Therefore they are not water quality 

standards subject to EPA review and approval under 303(c) of the CWA. As a result, EPA is 

taking no action to approve or disapprove the revised footnotes for these six pollutants.

The revised footnotes identified above explain in more detail than the previous footnotes that the 

criteria are based upon a Safe Drinking Water MCL value in addition to an explanation 

concerning the rationale for why an “organism only” criterion does not exist. These human 

health criteria were not derived using EPA’s 2000 Methodology, but instead were based upon 

EPA’s national 304(a) criteria recommendations in EPA’s 1986 Gold Book and developed under 

the Safe Drinking Water Act. EPA has reviewed these footnotes and found them to be accurate 

regarding the human health criteria development for these six pollutants. The underlying toxics 

criteria for asbestos and copper were approved by EPA on June 1, 2010. The underlying toxics 

criteria for chlorophenoxy herbicide (2,4,5,-TP), chlorophenoxy herbicide (2,4,-D),

methoxychlor, and nitrates have not been revised and thus are not addressed in this action. These 

values remain consistent with EPA’s current 304(a) criteria recommendations. 

3. Withdrawn Footnotes 

ODEQ has removed the footnote below for the three pollutants to which it applied: 

hexachlorocyclo-hexane-technical, nitrosamines, and nitrosodiethylamine, N: 

No BCF was available; therefore, this value is based on that published in the 1986 Gold Book. 

EPA Review

EPA’s current CWA 304(a) criteria recommendations include the following BCF values for 

these three pollutants: 

• Hexachlorocyclo-hexane-technical: BCF value = 130

• Nitrosamines: BCF value = 0.20

• Nitrosodiethylamine, N: BCF value = 0.20

At the time of Oregon’s previous adoption of human health criteria for these three pollutants, 

EPA’s 304(a) criteria recommendations were not derived using a methodology that accounted for 

bioconcentration through the use of a BCF. EPA now recommends the use of the BCF values 

listed above. Consistent with EPA’s recommended 304(a) national default values for calculating 

the human health criteria, ODEQ has updated the criteria for these three pollutants to include 

EPA’s recommended BCF values and therefore the three footnotes are no longer accurate or 

relevant. EPA is approving Oregon’s human health criteria for hexachlorocyclo-hexane-
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technical, nitrosamines, and nitrosodiethylamine, N as discussed above in section IV as

consistent with EPA’s 304(a) guidance. 

Therefore, as a result of updating the human health criteria for these three pollutants, the 

footnotes are no longer accurate and relevant and removing them is appropriate. Furthermore, 

these three footnotes were not water quality standards because they did not establish legally 

binding requirements under state law and they did not describe a desired ambient condition of a 

waterbody to support a particulate designated use. Rather, the footnotes clarified the source of 

information, EPA’s 1986 Gold Book, upon which the criteria were based. For this reason, the 

footnotes were not considered WQS subject to EPA review and approval under 303(c) of the 

CWA. As a result, EPA is taking no action to approve or disapprove the removal of the footnote 

as applied to hexachlorocyclo-hexane-technical, nitrosamines, and nitrosodiethylamine, N.

G. WITHDRAWN HUMAN HEALTH CRITERIA WHICH WERE 

REPLACED BY MORE SPECIFIC CRITERIA 

During this rule revision, Oregon updated its numeric human health toxics criteria to reflect 

EPA's most recent science and refinements as published in EPA’s current CWA § 304(a) criteria 

recommendations. Included in the refinements recommended by EPA was the removal of 13 

general human health criteria developed for families of pollutants and the replacement of these 

criteria by other criteria that address the specific chemical(s) of concern for human health 

protection. The 13 chemicals that ODEQ has removed and replaced with criteria for specific 

chemical compounds are consistent with EPA’s current 304(a) criteria recommendations. They 

are listed and explained in Table 13 below. 

Table 13: Withdrawn human health criteria replaced with more specific criteria.

No. Withdrawn Criteria Replacement Criteria Explanation125

1 Dinitrotoluene Dinitrotoluene 2,4 More specific and more 

stringent of the two compounds 

was retained.

2 Dinitro-o-Cresol 2,4 Dinitrophenol 2,4; Dinitrophenols Alternative compounds, 

including a synonym, in the 

same family identified.

3 Diphenylhydrazine Diphenylhydrazine 1,2 More specific compound in the 

same family identified. 

4 Endosulfan Endosulfan Alpha; Endosulfan Beta; 

Endosulfan Sulfate

More specific compounds in the 

same family identified.

5 Halomethanes Chlorodibromomethane; 

Dichlorobromomethane; Bromoform; 

Chloroform 

More specific compounds in the 

same family identified.

6 Monochlorobenzene Chlorobenzene Identical compound, the two 

criteria names are synonyms.

 

125 Explanations in the table were developed with information from EPA’s “Gold Book”. EPA. May 1, 1986. Quality 

Criteria for Water. U.S. Environmental Protection Agency, Office of Water. 440/5-86-001. Available at: 

https://owpubauthor.epa.gov/scitech/swguidance/standards/upload/2009_01_13_criteria_goldbook.pdf 
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7 Polynuclear Aromatic 

Hydrocarbons 

Acenaphthene; Anthracene; Fluorene; 

Fluoranthene; Pyrene; Chyrsene; 

Dibenzo(a,h)anthracene; 

Benzo(a)anthracene; Benzo(a)pyrene; 

Benzo(b)fluorantehene 3,4; 

Benzo(k)fluoranthene; 

Indeno(1,2,3-cd)pyrene

More specific compounds in the 

same family identified.

8 Chlorinated Benzenes Chlorobenzene More specific compound in the 

same family identified.

9 DDT DDD 4,4’; DDE 4,4’; DDT 4,4’ More specific compounds in the 

same family identified.

10 Dichlorobenzenes Dichlorobenzene(m) 1,3; 

Dichlorobenzene(o)1,2; 

Dichlorobenzene(p) 1,4

More specific compounds in the

same family identified.

11 Dichloroethylenes Dichloroethylene 1,1; 

Dichloroethylene trans 1,2 

More specific compounds in the 

same family identified.

12 Dichlorobenzidine Dichlorobenzidine 3,3’ More specific and more 

sensitive of the two compounds 

was retained.

13 Dichloropropene Dichloropropene 1,3 More specific and more 

sensitive of the two compounds 

was retained.

Note: Chemicals listed in italics are criteria that Oregon had previously adopted and which EPA had 

previously approved. EPA is taking no action on these criteria. All other pollutants listed in the 

replacement criteria column, new criteria have been adopted by Oregon and are approved by EPA as part 

of this action. 

EPA Review

In 2000 and 2003 EPA refined its “priority” list of toxic pollutants and 304(a) human health 

criteria recommendations specific to a number of pollutants on that list.126 The criteria for the 13 

pollutants listed above have been refined in three ways: 

1. EPA previously had established recommended criteria for large chemical families of 

pollutants. Advances in scientific information have allowed EPA to refine its criteria 

recommendations by developing criteria for specific chemical forms (i.e. isomers or 

congeners) of a pollutant within the larger chemical family. For example, while the 

Gold Book published only a single criterion for DDT, subsequent revisions (see 

EPA’s 2004 National Recommended Water Quality Criteria) have resulted in 

multiple criteria for DDT and two metabolites: 4,4’ DDT, 4,4’ DDE and 4,4’ DDD. 

Similarly, while the Gold Book recommended a single criterion for dichlorobenzenes 

in the Gold Book, EPA’s 2004 National Recommended Water Quality Criteria, 

recommends criteria for 1,2-dichlorobenzene, 1,3-dichlorobenzene, and 1,4-

dichlorobenezene;

 

126 November 3, 2000. Federal Register, Volume: 65, Issue: 214, page: 66443 (65 FR 66443). Available at: 

http://www.epa.gov/fedrgstr/EPA-WATER/2000/November/Day-03/w27924.htm

December 31, 2003. Federal Register, Volume: 68, Issue: 250, page: 75507 (68 FR 75507). Available at: 

http://edocket.access.gpo.gov/2003/pdf/03-32211.pdf 
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2. EPA has replaced some of the toxic pollutant names with synonyms for specific 

chemicals.127

3. EPA has condensed certain pollutants from several chemical forms of a given 

compound into a single compound, such as recommending criteria for total arsenic in 

EPA’s 2004 National Recommended Water Quality Criteria to replace the previously 

recommended criteria for arsenic (tri) and arsenic (pent) as published in the Gold 

Book. 

 For example, while the Gold Book contained criteria for 

hexachlorocyclohexane-alpha, hexachlorocyclohexane-beta, and 

hexachlorocyclohexane-gamma, these criteria are now listed under the synonyms 

alpha BHC, beta BHC and gamma BHC in EPA’s National Recommended Water 

Quality Criteria; and

In updating its numeric toxics human health criteria, Oregon revised the criteria consistent with 

EPA's most recent CWA § 304(a) criteria recommendations, including withdrawing and/or 

revising the criteria as recommended by the above changes. The criteria withdrawn based on 

these refinements in chemical names are identified in Table 13 above. The table further 

identifies the pollutants for which Oregon has adopted new criteria to address the human health 

impacts associated with these pollutants. EPA action on the new criteria were addressed 

previously as part of EPA’s action on Oregon’s new criteria in section IV.B. 

EPA Approval 

In accordance with its Clean Water Act authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, 

EPA approves the withdrawal of Oregon’s human health criteria for the 13 pollutants identified 

in Table 13, coupled with EPA’s approval of new criteria (in section IV.B), as protective of 

human health. These changes are consistent with EPA’s current CWA § 304(a) criteria 

recommendations to replace the specified criteria with more specific criteria for associated 

pollutants consistent with the latest science. EPA has approved the more specific pollutant 

replacement criteria above as consistent with 40 C.F.R. part 131. Since these new criteria 

address the same human health affects as the withdrawn criteria, EPA finds the criteria for the 13 

pollutants identified above are not necessary to protect Oregon’s fishing and water supply uses.

EPA Rationale 

The CWA requires that, whenever a state or authorized tribe revises or adopts new WQS, it 

adopt criteria for all toxic pollutants listed pursuant to CWA § 307(a)(1) for which EPA has 

developed recommended criteria under CWA § 304(a), the discharge or presence of which in the 

affected waters could reasonably be expected to interfere with the adopted designated uses 

(CWA § 303(c)(2)(B)). As noted above, Oregon has refined the list of criteria for which it has 

established human health criteria to reflect recent science incorporated by EPA into the § 304(a) 

 

127 In addition, the following pollutant names were modified by ODEQ from their previous human health criteria for 

consistency with EPA terminology. These compounds are synonyms.

1. Dibutylphthalate was changed to Di-n-butyl Phthalate

2. Di-2-ethylhexyl phthalate was changed to Ethylhexyl phthalate bis 2

3. Hexachlorocyclohexane-alpha was changed to BHC alpha

4. Hexachlorocyclohexane-beta was changed to BHC beta

5. Hexachlorocyclohexane-gamma was changed to BHC gamma (Lindane)
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human health criteria recommendations, including the removal of several pollutants representing 

chemical families and replacing them with criteria for more specific chemical compounds within 

the same general family. As such, the changes in the pollutant names listed above and the 

criteria adopted for these pollutants represent a refinement of criteria for individual chemicals 

within families, not withdrawals of criteria identified for pollutants in CWA § 307(a). 

Therefore, Oregon’s withdrawal of its previous human health water quality criteria for these 13 

pollutants is consistent with CWA § 303(c)(2)(B). 

As stated above, Oregon’s removal of these 13 pollutants and the associated criteria is consistent 

with EPA’s removal of 304(a) criteria recommendations. Although the criteria for these 13 

pollutants have been withdrawn, Oregon has developed individual criteria for the most toxic of 

chemicals in that family or retained the more specific criteria or a synonym for the chemical 

compounds. Therefore, while withdrawing the criteria for these 13 pollutants, Oregon has 

adopted new criteria to protect the same human health endpoints which these criteria were 

originally developed to protect. Therefore, EPA has determined that the withdrawal of these 

criteria coupled with the adoption of new criteria for similar pollutants (approved above in 

section IV.B) will protect Oregon’s human health uses in accordance with 40 C.F.R. part 

131.11(a)(1). 

H. TABLE 40 HUMAN HEALTH CRITERIA SUMMARY

Oregon has added the following summary language prior to the human health criteria in Table 40 

which explains the purpose of the criteria, criteria derivation and the format of the table.

TABLE 40: Human Health Water Quality Criteria for Toxic Pollutants

Human Health Criteria Summary

The concentration for each pollutant listed in Table 40 was derived to protect Oregonians from 

potential adverse health impacts associated with long-term exposure to toxic substances 

associated with consumption of fish, shellfish, and water. The “organism only” criteria are 

established to protect fish and shellfish consumption and apply to waters of the state designated 

for fishing. The “water + organism” criteria are established to protect the consumption of 

drinking water, fish, and shellfish, and apply where both fishing and domestic water supply 

(public and private) are designated uses. All criteria are expressed as micrograms per liter 

(μg/L), unless otherwise noted. Pollutants are listed in alphabetical order. Additional 

information includes the Chemical Abstract Service (CAS) number, whether the criterion is 

based on carcinogenic effects (can cause cancer in humans), and whether there is an aquatic life 

criterion for the pollutant (i.e. “y”= yes, “n” = no). All the human health criteria were 

calculated using a fish consumption rate of 175 grams per day unless otherwise noted. A fish 

consumption rate of 175 grams per day is approximately equal to 23 8-ounce fish meals per 

month. For pollutants categorized as carcinogens, values represent a cancer risk of one 

additional case of cancer in one million people (i.e. 10-6), unless otherwise noted. All metals 

criteria are for total metal concentration, unless otherwise noted. Italicized pollutants represent 

non-priority pollutants. The human health criteria revisions established by OAR 340-041-0033 
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and shown in Table 40 do not become applicable for purposes of ORS chapter 468B or the 

federal Clean Water Act until approved by EPA pursuant to 40 CFR 131.21 (4/27/2000).

Acknowledgement of Table 40 Summary Language 

The new introductory summary language for Table 40 explains the purpose of the criteria, 

criteria derivation and the format of the table. However, this language does not establish a 

legally binding requirement under State law and it does not describe a desired ambient condition 

of a waterbody to support a particular designated use it is not considered a WQS subject to EPA 

review and approval under 303(c) of the CWA. EPA has addressed the new and revised 

underlying human health criteria in Table 40 and the narrative language at OAR 340-041-

0033(4) in this technical support document. This summary language further explains how the 

state derived the criteria values in Table 40. EPA incorporated the explanatory information 

provided in this summary into its analysis of the individual criteria values in Table 40. But 

because this summary does not operate as an independent water quality standard, in isolation 

from the criteria values in Table 40 and the narrative language at OAR 340-041-0033(4) (which 

EPA acted on individually), EPA is taking no action to approve or disapprove this summary 

language.
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V. NARRATIVE STATEMENT

Oregon’s revisions to its narrative toxics provisions found at OAR 340-041-033(1), (3) and (4) 

are shown in underline/strikeout format below. Underlined text represents added text, while text 

with a line through the middle (strikeout) represents deleted text. Non-revised words are also 

provided below for context. Additionally, Oregon reorganized sections of OAR 340-041-0033, 

thus renumbering several of the provisions without substantively changing any of the regulatory 

language.

340-041-0033 

Toxic Substances

(1) Amendments to sections (4) and (6) of this rule (OAR 340-041-0033) and associated 

revisions to Tables 20, 33A, 33B and 40 do not become applicable for purposes of ORS chapter 

468B or the federal Clean Water Act unless and until EPA approves the provisions it identifies 

as water quality standards pursuant to 40 CFR 131.21 (4/27/2000).

(3) Aquatic Life Criteria. Levels of toxic substances in waters of the state may not exceed the 

applicable aquatic life criteria listed in Tables 20, 33A, and 33B. Tables 33A and 33B, adopted 

on May 20, 2004, update Table 20 as described in this section. 

EPA Action

In accordance with its Clean Water Act authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, 

EPA approves the new and revised language at OAR 340-041-0033(1) and (3).

EPA Rationale

The new and revised provisions at OAR 340-041-0033(1) and (3) describe dates when the toxics 

criteria in Tables 20, 33A, 33B and 40 become effective under state law and the Clean Water 

Act. The effective date of WQS provisions under the CWA is determined by the date of EPA 

approval. These timing provisions are WQS that provide for the new and revised criteria to be 

immediately in effect at the time of EPA’s approval action. EPA has addressed the new and 

revised underlying human health criteria in this technical support document. OAR 340-041-

0033(3) clarifies that only aquatic life criteria remain in Tables 20, 33A and 33B. EPA will 

address the aquatic life criteria in these tables and their corresponding footnotes in a separate 

action.

(4) Human Health Criteria. The criteria for waters of the state listed in Table 40 are established 

to protect Oregonians from potential adverse health effects associated with long-term exposure 

to toxic substances associated with consumption of fish, shellfish, and water.

EPA Action

In accordance with its Clean Water Act authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, 

EPA approves the new language at OAR 340-041-0033(4).
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EPA Rationale

The new provision at OAR 340-041-0033(4) adopts the human health criteria in Table 40. EPA 

approves this language which adopts the criteria and describes the intent of the criteria to protect 

human health uses in Oregon. This language explains the purpose of the human health criteria 

and describes that the criteria in Table 40 are established to protect Oregonians from potential 

adverse health effects association with long-term exposure to toxic substances associated with 

fish, shellfish and water consumption. EPA’s action on each individual criterion in Table 40 is 

described in detail above. 
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VI. BACKGROUND POLLUTANT CRITERIA PROVISION

A. BACKGROUND

As previously discussed, in October 2008, the Oregon Environmental Quality Commission 

directed ODEQ to revise the State’s human health criteria to incorporate a fish consumption rate 

of 175 grams per day. The fish consumption rate of 175 grams per day was selected by Oregon 

to ensure protection of all people in Oregon who may consume fish and shellfish from State 

waters including those who traditionally consume high amounts of fish for subsistence, health, 

economic or other reasons.128 The rate reflects the 95th percentile of tribal members surveyed as 

part of the CRITFC Survey129 and the 90th percentile of subsistence consumers surveyed in 

regional fish consumption studies. When providing this direction, the Commission also directed 

ODEQ to “propose rule language that would allow [O]DEQ to implement the standards in 

NPDES permits and other Clean Water Act programs in an environmentally meaningful and 

cost-effective manner” and to carefully consider the costs and benefits associated with elements 

of the new rule. This latter directive came following testimony from several stakeholders 

regarding potential implementation difficulties and economic burden of adopting the more 

stringent criteria.130 

In response to this direction, ODEQ not only revised the human health criteria but also 

developed several new and revised rules addressing the implementation of the revised criteria. 

Each revised implementation rule targeted specific situations raised as potential concerns by 

ODEQ staff and stakeholders. The adoption of a new site-specific background pollutant criterion 

provision and the revisions to the variance provision (discussed in previous section) were 

submitted to EPA for action under Section 303(c) of the CWA while other rules were adopted 

pursuant to state law and were not submitted to EPA. All revisions are addressed separately in 

this document. 

Oregon developed an Issue Paper: Implementing Water Quality Standards for Toxic Pollutants 

in NPDES Permits, Human Health Toxics Rulemaking131

 

128 ODEQ. October 6, 2008. Memo from Dick Pederson, Director ODEQ, to the Environmental Quality 

Commission. Agenda Item G, Action Item: Oregon’s Fish Consumption Rate – For Use in Setting Water Quality 

Standards for Toxic Pollutants October 23, 2008 EQC Meeting. Oregon Department of Environmental Quality. 

page 7. Available at: 

that discusses how ODEQ will 

implement the revised criteria in NPDES permits. Section IV.3 of this paper speaks directly to 

the site-specific background pollutant criterion provision and provides greater detail on its 

purpose, development and content as well as providing some discussion of how the resultant 

http://www.deq.state.or.us/about/eqc/agendas/attachments/2008oct/ItemG.pdf

129 Columbia River Inter-Tribal Fish Commission (CRITFC). October 1994. A Fish Consumption Survey of the 

Umatilla, Nez Perce, Yakama, and Warm Springs Tribes of the Columbia River Basin. Technical Report 94.3. 

Available at: http://www.critfc.org/tech/94-3report.pdf 130 Oregon Environmental Quality Commission (OEQC). October 23, 2008. Oregon Environmental Quality 

Commission Minutes of the Three Hundred and Forty-sixth Meeting. Available at: 

http://www.deq.state.or.us/about/eqc/minutes/2008/2008octEQCMinutes.htm 131 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf
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criterion would be applied to NPDES permits.132 Other issue papers were developed to address 

implementation of the criteria outside of the NPDES program including papers that address 

nonpoint sources, antidegradation and source control.133

One situation identified during the workgroup process as potentially problematic to dischargers 

as well as ODEQ when issuing NPDES permits as a result of the revised human health criteria is 

when a NPDES discharger takes in water from and discharges to the same waterbody, which 

contains pollutants from upstream sources over which the discharger has little to no control. 

ODEQ adopted an intake credit provision at OAR 340-045-0105 that does not hold facilities 

accountable for removing these upstream pollutants if the concentration of the pollutant does not 

exceed the water quality criteria, the facility does not chemically or physically modify the 

pollutant and several other conditions described in the rule are met. 

However, facilities that concentrate pollutants in their discharge above the levels in the intake 

water are not eligible for the intake credit rule. For example, such an increase in concentration 

may occur when a facility’s process involves evaporation (e.g. non-contact cooling water), and 

the facility recycles water, thus resulting in the same mass of the pollutant but a lower volume of 

water. If the upstream concentration of the pollutant in the waterbody exceeds the underlying 

criterion, a permit limit is established such that the criterion is met at the end of the discharge 

pipe and the facility would need to treat the water prior to discharge regardless of the upstream 

concentration.134

ODEQ discussed numerous options for addressing this type of situation with the objective for 

providing an approach that: 

• protects human health; 

• establishes reasonable implementation of the revised water quality standards for facilities 

in the situation described above; 

• allocates limited State resources efficiently; and 

 

132 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. Section IV.3, pages 

44-61. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf 133 ODEQ. May 26, 2011. Issue Paper: Revisions to the Water Quality Standards and TMDL Rules (Divisions 41 

and 42), Clarifications on How Nonpoint Sources Meet Water Quality Standards, Human Health Toxics 

Rulemaking. Oregon Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/Div4142IssuePaper.pdf 

ODEQ. December 29, 2010. Issue Paper: Evaluating the Antidegradation Policy as a Means to Reduce Nonpoint 

Sources of Toxic Pollutants to Oregon Waters, Human Health Toxics Rulemaking. Oregon Department of 

Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/AntidegIssuePaper.pdf 

ODEQ. December 29, 2010. Issue Paper: Source Control Small Group, Human Health Toxics Rulemaking. Oregon 

Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/SourceControlIssuePaper.pdf 134 ODEQ. April 20, 2010. Implementing Water Quality Standards for Toxic Pollutants in Clean Water Act Permits.

DRAFT. RWG April 27, 2010 Discussion. Oregon Department of Environmental Quality. page 6. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/BackgroundPollutantsIssuePaper20110427.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

72

• ensures that regulatory requirements and costs for a facility are commensurate with the 

environmental threat they pose.135

Oregon proposed a draft rule and accepted public comment on that rule during the public process 

described above for all other elements of this action submitted by Oregon on July 21, 2011. In 

EPA’s public comments to ODEQ on March 21, 2011 regarding the previous version of the 

background pollutant criteria provision proposed for public comment, EPA stated that ODEQ 

could: 

• Implement the criterion on a site specific basis and submit each application to EPA for 

evaluation on a case by case basis; or

• Revise the provision consistent with a performance-based approach as a viable alternative 

to submitting each revision to EPA on a site specific basis. If ODEQ were to choose this 

option, sufficiently detailed implementation procedures would need to be adopted 

directly into the WQS regulations which establish a framework that is binding, clear, 

predictable and transparent. 

Following consideration of the comments received, ODEQ adopted a performance-based water 

quality standard that can be used to adopt site-specific criteria for human health carcinogens 

where all of the following conditions apply: 

• The criterion at issue is a human health criterion, for a pollutant identified as a 

carcinogen. 

• The discharge does not increase the mass load of the pollutant in the receiving water. 

The mass load of the pollutant discharged to a waterbody may not exceed the mass load 

of the pollutant taken in from the same waterbody or a hydrologically connected water. 

• The pollutant concentration in the receiving water is not increased by more than 3% 

above the upstream ambient concentration. 

• The water body concentration does not exceed a calculated value that represents the 

human health criterion calculated at a risk level of 10-4. 

• The discharger uses any feasible pollutant reduction measures known and available to 

minimize the pollutant concentration in their discharge.

• The criterion must be evaluated and revised, if appropriate, when the permit is reissued. 

• No TMDL has been developed for the waterbody and pollutant at issue.136 

The provision authorizes ODEQ to develop a site-specific criterion for the waterbody in the 

vicinity of a discharge and use that criterion to develop an effluent limit for the pollutant if all 

conditions of the rule are met. The criterion established would be based upon the most stringent 

of 1) the instream concentration following receipt of the current level of discharge from the 

 

135 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. pages 45-46. 

Available at: http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf 136 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. pages 44-45. 

Available at: http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

73

facility, 2) a 3% increase in the ambient instream concentration of the pollutant, or 3) a 

concentration value that represents a 1 × 10-4 risk level. In addition, the criterion could not be 

established at a level that would allow the facility to increase the mass load of the pollutant from 

that in their intake water.137

A site-specific background pollutant criterion may only be developed under this provision if the 

waterbody serves as the receiving water for a NPDES discharge and the effluent discharged 

meets certain requirements. Oregon’s rule limits the criteria developed under this rule by 

requiring the criteria be established at the most stringent of several options that are based on 

applying certain limitations on the effluent from the facility and on the resultant instream criteria. 

Therefore, the process outlined in Oregon’s rule uses the same type of calculations made in 

establishing NPDES permit limits to calculate the resultant instream concentration at various 

effluent conditions. Once a site-specific criterion is adopted, it is to be used to develop permit 

effluent limits in the same manner as any other criteria.138 

In order to provide further guidance to their permit writers ODEQ will be developing an Internal 

Management Directive (IMD) within 180 days of EPA’s approval action.139 This is one of 

several items identified by ODEQ as actions necessary to assist ODEQ staff and the public in 

implementing the provisions approved in this action. 

B. ODEQ’S JULY 21, 2011 SUBMITTAL

ODEQ has added a new provision which establishes a site-specific background pollutant criteria 

at OAR 340-041-0033(6). This provision is a performance-based water quality standard that 

results in site-specific human health water quality criteria under the conditions and procedures 

specified within the rule. It addresses existing permitted discharges of a pollutant removed from 

the same body of water, as defined in the provision. 

Below is Oregon’s background pollutant criteria provision, found at OAR 340-041-0033(6). 

340-041-0033(6) 

Establishing Site-Specific Background Pollutant Criteria: This provision is a performance-based water 

quality standard that results in site-specific human health water quality criteria under the conditions and 

procedures specified in this rule section. It addresses existing permitted discharges of a pollutant 

 

137 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. page 44. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf

138 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. page 60. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf

139 ODEQ. June 2, 2011. Memorandum from Dick Pedersen to Environmental Quality Commission; Agenda item C, 

Rule adoption: Revised water quality standards for human health and revised water quality standards 

implementation policies, June 15-17, EQC meeting. Oregon Department of Environmental Quality. Supplemental 

Attachment 10, Timeline for Follow-Up Actions, WQS for Human Health Toxic Pollutants Rulemaking.
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

74

removed from the same body of water. For waterbodies where a discharge does not increase the 

pollutant’s mass and does not increase the pollutant concentration by more than 3%, and where the water 

body meets a pollutant concentration associated with a risk level of 1x10-4, DEQ concludes that the 

pollutant concentration continues to protect human health. 

(a) Definitions: For the purpose of this section [OAR 340-041-0033(6)]: 

(A) “Background pollutant concentration” means the ambient water body concentration 

immediately upstream of the discharge, regardless of whether those pollutants are natural or 

result from upstream human activity.

(B) An “intake pollutant” is the amount of a pollutant that is present in public waters (including 

groundwater) as provided in subsection (C), below, at the time it is withdrawn from such waters 

by the discharger or other facility supplying the discharger with intake water.

(C) “Same body of water”: An intake pollutant is considered to be from the “same body of 

water” as the discharge if the department finds that the intake pollutant would have reached the 

vicinity of the outfall point in the receiving water within a reasonable period had it not been 

removed by the permittee. This finding may be deemed established if:

(i) The background concentration of the pollutant in the receiving water (excluding any 

amount of the pollutant in the facility's discharge) is similar to that in the intake water; 

(ii) There is a direct hydrological connection between the intake and discharge points; 

and 

(I) The department may also consider other site-specific factors relevant to the 

transport and fate of the pollutant to make the finding in a particular case that a 

pollutant would or would not have reached the vicinity of the outfall point in the 

receiving water within a reasonable period had it not been removed by the 

permittee.

(II) An intake pollutant from groundwater may be considered to be from the 

“same body of water” if the department determines that the pollutant would have 

reached the vicinity of the outfall point in the receiving water within a 

reasonable period had it not been removed by the permittee, except that such a 

pollutant is not from the same body of water if the groundwater contains the 

pollutant partially or entirely due to past or present human activity, such as 

industrial, commercial, or municipal operations, disposal actions, or treatment 

processes.

(iii) Water quality characteristics (e.g., temperature, pH, hardness) are similar in the 

intake and receiving waters.

(b) Applicability

(A) Site-specific criteria may be established under this rule section only for carcinogenic 

pollutants. 

(B) Site-specific criteria established under this rule section apply in the vicinity of the discharge 
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for purposes of establishing permit limits for the specified permittee.

(C) The underlying waterbody criteria continue to apply for all other Clean Water Act programs. 

(D) The site-specific background pollutant criterion will be effective upon department issuance of 

the permit for the specified permittee.

(E) Any site-specific criteria developed under this procedure will be re-evaluated upon permit 

renewal.

(c) A site-specific background pollutant criterion may be established where all of the following conditions 

are met:

(A) The discharger has a currently effective NPDES permit;

(B) The mass of the pollutant discharged to the receiving waterbody does not exceed the mass of 

the intake pollutant from the same body of water, as defined in section 6(a)(C) above, and, 

therefore, does not increase the total mass load of the pollutant in the receiving water body; 

(C) The discharger has not been assigned a TMDL wasteload allocation for the pollutant in 

question; 

(D) The permittee uses any feasible pollutant reduction measures available and known to 

minimize the pollutant concentration in their discharge; 

(E) The pollutant discharge has not been chemically or physically altered in a manner that 

causes adverse water quality impacts that would not occur if the intake pollutants were left instream; and, 

(F) The timing and location of the pollutant discharge would not cause adverse water quality 

impacts that would not occur if the intake pollutant were left in-stream.

(d) The site-specific background pollutant criterion must be the most conservative of the following four 

values. The procedures deriving these values are described in the sections (6)(e) of this rule. 

(A) The projected in-stream pollutant concentration resulting from the current discharge 

concentration and any feasible pollutant reduction measures under (c)(D) above, after mixing 

with the receiving stream.

(B) The projected in-stream pollutant concentration resulting from the portion of the current 

discharge concentration associated with the intake pollutant mass after mixing with the receiving 

stream. This analysis ensures that there will be no increase in the mass of the intake pollutant in 

the receiving water body as required by condition (c)(B) above. 

(C) The projected in-stream pollutant concentration associated with a 3% increase above the 

background pollutant concentration as calculated: 

(i) For the mainstem Willamette and Columbia Rivers, using 25% of the harmonic mean 

flow of the waterbody. 

(ii) For all other waters, using 100% of the harmonic mean flow or similar critical flow 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

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value of the waterbody. 

(D) A criterion concentration value representing a human health risk level of 1 × 10-4. This value 

is calculated using EPA’s human health criteria derivation equation for carcinogens (EPA 2000), 

a risk level of 1 × 10-4, and the same values for the remaining calculation variables that were 

used to derive the underlying human health criterion. 

(e) Procedure to derive a site-specific human health water quality criterion to address a background 

pollutant: 

(A) The department will develop a flow-weighted characterization of the relevant flows and 

pollutant concentrations of the receiving waterbody, effluent and all facility intake pollutant 

sources to determine the fate and transport of the pollutant mass. 

(i) The pollutant mass in the effluent discharged to a receiving waterbody may not exceed 

the mass of the intake pollutant from the same body of water. 

(ii) Where a facility discharges intake pollutants from multiple sources that originate 

from the receiving waterbody and from other waterbodies, the department will calculate 

the flow-weighted amount of each source of the pollutant in the characterization. 

(iii) Where intake water for a facility is provided by a municipal water supply system and 

the supplier provides treatment of the raw water that removes an intake water pollutant, 

the concentration and mass of the intake water pollutant shall be determined at the point 

where the water enters the water supplier’s distribution system.

(B) Using the flow weighted characterization developed in Section (6)(e)(A), the department will 

calculate the in-stream pollutant concentration following mixing of the discharge into the 

receiving water. The resultant concentration will be used to determine the conditions in Section 

(6)(d)(A) and (B).

(C) Using the flow weighted characterization, the department will calculate the in-stream 

pollutant concentration based on an increase of 3% above background pollutant concentration. 

The resultant concentration will be used to determine the condition in Section (6)(d)(C).

(i) For the mainstem Willamette and Columbia Rivers, 25% of the harmonic mean flow of 

the waterbody will be used.

(ii) For all other waters, 100% of the harmonic mean flow or similar critical flow value 

of the waterbody will be used. 

(D) The department will select the most conservative of the following values as the site-specific 

water quality criterion. 

(i) The projected in-stream pollutant concentration described in Section 6(e)(B); 

(ii) The in-stream pollutant concentration based on an increase of 3% above background 

described in Section 6(e)(C); or 

(iii) A water quality criterion based on a risk level of 1 x 10-4. 
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(f) Calculation of water quality based effluent limits based on a site-specific background pollutant 

criterion:

(A) For discharges to receiving waters with a site-specific background pollutant criterion, the 

department will use the site-specific criterion in the calculation of a numeric water quality based 

effluent limit.

(B) The department will compare the calculated water quality based effluent limits to any 

applicable aquatic toxicity or technology based effluent limits and select the most conservative 

for inclusion in the permit conditions. 

(g) In addition to the water quality based effluent limits described in Section (6)(f), the department will 

calculate a mass-based limit where necessary to ensure that the condition described in Section (6)(c)(B) 

is met. Where mass-based limits are included, the permit shall specify how compliance with mass-based 

effluent limitations will be assessed.

(h) The permit shall include a provision requiring the department to consider the re-opening of the permit 

and reevaluation of the site-specific background pollutant criterion if new information shows the 

discharger no longer meets the conditions described in subsections (6)(c) and (e). 

(i) Public Notification Requirements.

(A) If the department proposes to grant a site-specific background pollutant criterion, it must 

provide public notice of the proposal and hold a public hearing. The public notice may be 

included in the public notification of a draft NPDES permit or other draft regulatory decision 

that would rely on the criterion and will also be published on the water quality standards 

website;

(B) The department will publish a list of all site-specific background pollutant criteria approved 

pursuant to this rule. A criterion will be added to this list within 30 days of its effective date. The 

list will identify: the permittee; the site-specific background pollutant criterion and the associated 

risk level; the waterbody to which the criterion applies; the allowable pollutant effluent limit; and 

how to obtain additional information about the criterion.

C. EPA ACTION ON ODEQ’S NEW BACKGROUND POLLUTANT 

CRITERIA PROVISION

EPA Action

In accordance with its CWA authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, EPA 

approves Oregon’s new background pollutant criteria provision at OAR 340-041-0033(6), as 

detailed below, because it is consistent with the Clean Water Act and the implementing Federal 

water quality standards regulations governing EPA’s review and approval or disapproval of new 

or revised water quality standards as required in 40 C.F.R. part 131. In EPA’s review of 

Oregon’s background pollutant criteria provision, the Agency considered information submitted 

on July 21, 2011 including ODEQ’s NPDES Implementation Issue Paper140

 

140 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. Available at: 

 and Response to 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

78

Comments document.141

In its review and action on the background pollutant provision, EPA also considered the 

following three key elements: 

• Whether the site-specific human health criteria to be generated under the provision are 

sufficient to protect Oregon’s human health uses, as required under 40 CFR 131.6. 

• Whether the site-specific human health criteria to be generated under the provision are 

consistent with EPA’s regulatory specifications for criteria at 40 CFR 131.11. 

• Whether this implementation procedure contains sufficient detail, and suitable 

safeguards, such that additional § 303(c) review of individual criteria generated under the 

provision would be redundant. 

As described in further detail below, EPA has concluded that the site-specific background 

pollutant provision adequately addresses all three of these elements and thus is consistent with 

CWA § 303(c) and its implementing regulations. 

EPA Rationale

The provision establishes site-specific human health criteria at a level to protect Oregon’s 

human health uses 

Oregon’s site-specific background pollutant provision contains a binding restriction that any sitespecific criterion to be generated under the provision must be established at the most 

conservative (stringent) of the conditions specified in OAR 340-041-033(6)(d) and reflect no net 

addition of the pollutant from the discharger to the waterbody segment. In no case may a 

criterion developed under this provision represent a carcinogenic human health risk level greater 

than 1.0 x10-4, however, it may be more stringent. Since the least stringent scenario for a sitespecific criterion generated under the provision (i.e., one generated based on a 10-4 risk level) is 

itself within EPA’s recommended range of risk levels protective of human health designated 

uses, EPA concludes that a criterion developed using Oregon’s site-specific background 

pollutant provision would be protective of Oregon’s human health uses. 

EPA’s Human Health Methodology recognizes that States and Tribes have discretion in selecting 

appropriate risk ranges and recommends that states adopt criteria for carcinogens based on either 

a 1 x 10-6 or 1 x 10-5 risk level to protect the general population, as long as highly exposed 

populations do not exceed a 1 x 10-4 risk level.142

 http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf

 Consistent with the flexibility accorded to 

States in developing risk ranges for carcinogenic pollutants, Oregon has chosen to exercise this 

discretion by allowing the risk level for carcinogens in waters in the vicinity of certain NPDES 

discharges not to exceed 10-4. As discussed previously, Oregon used a fish consumption rate 

reflective of highly exposed consumers and a risk level of 1 x 10-6 for deriving their human 

141 ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 

Quality Standards Implementation Policies. Oregon Department of Environmental Quality. page 21. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf 142 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, EPA-822-B-00-004. page 2-6. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

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health criteria. In this case, the site specific criteria would continue to protect the highly exposed 

consumer but at a risk level between 1 x 10-6 and 1 x 10-4. Thus, EPA concludes that any sitespecific criterion calculated based on a 1 x 10-4 risk level would be consistent with EPA’s 

guidance with respect to highly exposed populations, since the fish consumption rate already 

reflects highly exposed populations. EPA has recommended using a fish consumption rate for 

the general US population of 17.5 grams per day if no local or regional data is available. There 

is currently no available fish consumption data specific to the general population of Oregon. If 

one were to evaluate the protectiveness of a site-specific criterion developed under this provision 

at a 10-4 risk level but using EPA’s default fish consumption rate of 17.5 grams per day, the 

result would protect at a carcinogenic risk level of 1 x 10-5. This risk level is consistent with 

that recommended by EPA by EPA in the 2000 Human Health Methodology. Therefore, EPA 

finds that criteria established under this provision would be established at a level protective of 

both the general population and high fish consuming populations consistent with the levels 

recommended by EPA in the 2000 Human Health Methodology. 

In response to several comments regarding the use of a 1 x 10-4 risk level, ODEQ affirmed that 

the criterion would be established at “the most protective of the following results: the current 

ambient pollutant concentration after discharge; the background concentration plus three percent; 

or the criteria value calculated at a 1 x 10-4 risk level” (emphasis added)).143 In several other 

responses to comments as well as at several places in the Issue Paper, ODEQ has also stated that 

a 1 x 10-4 risk would be the greatest possible risk allowed under the criterion and that other 

conditions within the provision would often limit the criterion further.144 ODEQ also specifies 

this fact in their July 21, 2011 letter to EPA requesting the review and approval of these rules.145

In ODEQ’s response to comments, they explained why they found this additional level of risk to 

be protective in this site-specific situation. They note that several restrictions have been included 

in the rule in order to limit any additional risk to the human health use. 

• First, the rule requires that the pollutant be from the “same body of water” and that the 

mass of the pollutant associated with the facility may not be increased from its intake 

water to the effluent water. These requirements ensure that any discharge limits based on 

the site specific criterion would not add any additional mass to the waterbody, although 

the discharger may slightly increase the pollutant concentration relative to background 

(up to a maximum of three percent). In other words, the pollutant present in the 

 

143 ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 

Quality Standards Implementation Policies. Oregon Department of Environmental Quality. page 54. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf 144 ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 

Quality Standards Implementation Policies. Oregon Department of Environmental Quality. pages 49; 55-58. 

Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf

ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. pages 47; 49; 50; 58. 

Available at: http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf 145 ODEQ. July 21, 2011. Letter from Neil Mullane, Water Quality Division Administrator, to Michael Bussell,

Office of Water and Watersheds, EPA Region 10. Re: Oregon Submission of Revised State Water Quality 

Standards for Toxic Pollutants, Including a New Background Pollutant Provision and a Revised Variance Rule for 

EPA Review and Approval.
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

80

waterbody segment to which the criteria will apply would have reached the vicinity of the 

outfall point had it not been intercepted by the discharger and there is no addition of 

pollutants by the facility.146

• Second, the application of the criterion is limited to the sole purpose of accommodating 

existing discharges from an existing NPDES discharger. In no case could a criterion 

decrease in stringency such that the current discharge concentration to a water body 

would be allowed to increase as a result of the revision.

 

147

• Third, the underlying water quality criterion will remain in effect for all other CWA 

purposes including 303(d) listing and TMDL development. (as explained above) 

 

• Finally, the rule requires that the criterion be re-evaluated upon permit renewal (OAR 

340-041-0033(6)(b)(E)), thus making the criterion effective only for the duration of the 

permit and requiring that the site-specific criterion be reevaluated and revised, if 

appropriate, upon permit renewal using current ambient and effluent data in situations 

where all the prerequisite conditions continue to be present.148 As noted above, if a 

TMDL was established prior to this renewal, a site-specific criterion could not be 

obtained under this rule and the facility’s effluent limit must be consistent with the WLA 

in the TMDL. 

ODEQ therefore determined that the relative increase in ambient concentration does not result in 

a significant change to human health risk149 and that the criterion developed under this provision 

would be protective of the beneficial uses of that waterbody.150

Since this provision establishes a process for developing individual site-specific criteria, the 

exact location of each application cannot be specified in advance. However, the provision does 

specify criteria location relative to the pertinent discharger (“in the vicinity of the discharge for 

purposes of establishing permit limits for the specified permittee”). (OAR 340-041-0033(6)(b)). 

Thus, dischargers other than the specified permittee would not be able to use the site-specific 

criterion in permit calculations.151

 

146 ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 

Quality Standards Implementation Policies. Oregon Department of Environmental Quality. page 51. Available at: 

 For the specified permitee, a site-specific criterion 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf

147 OAR 340-041-0033(6)(d)(A) and (B)

ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. page 44. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf 148 ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 

Quality Standards Implementation Policies. Oregon Department of Environmental Quality. page 60. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf

149 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. page 44. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf

150 ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 

Quality Standards Implementation Policies. Oregon Department of Environmental Quality. page 65. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf

151 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. page 44. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf

ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

81

corresponding to a risk level of 1 x 10-4 or safer would be applicable to the water in the vicinity 

of the discharge.152 Since the site-specific conditions are themselves predicated on the 

characteristics of the discharger, an appropriate matching of the criterion to discharger is an 

adequate specification of where the site-specific criteria will apply. 

EPA notes that one commenter was concerned that the approach in the proposed rule introduced 

an inconsistency into Oregon’s water quality criteria. The commenter questioned whether it was 

consistent with the Clean Water Act for Oregon to determine that a single risk target is both 

protective (where site-specific criteria apply) and non-protective (where site-specific criteria do 

not apply) of human health uses. ODEQ addressed this comment by adding additional detail in 

the final rule. In addition, EPA evaluated this concern relative to the final rule in light of the fact 

that Oregon already had the discretion, consistent with EPA’s Human Health Methodology, to 

adopt criteria based on a risk range between 1 x 10-6 and 1 x 10-4 (in conjunction with a fish 

consumption rate that reflects high-consuming populations). If Oregon had adopted state-wide 

criteria reflecting a risk range less stringent than 1 x 10-6, Oregon could have exercised its 

discretion, based on its own policy priorities and consistent with CWA § 510, to apply more 

stringent site-specific criteria where it deemed appropriate. Under these circumstances, a single 

risk target would be both protective (where site-specific criteria do not apply) and non-protective 

(where site-specific criteria apply). The only practical distinction between this scenario and the 

one raised in public comments is which risk level is treated as the normative baseline, and which 

is treated as site-specific departure from the baseline. 

Since multiple risk levels for carcinogenic pollutants are within the range identified as acceptable 

in EPA’s Human Health Methodology, and States/Tribes have the ability to define “local 

conditions” when establishing site specific criteria, EPA concludes that Oregon has discretion to 

apply both one risk level as a generally applicable value and other risk levels on a site-specific 

basis (i.e., as “site-specific conditions” under 40 CFR 131.11(b)). While the target risk level is 

combined with other values (based on a scientific rationale) to generate a criterion value for a 

carcinogenic pollutant, site-specific variation in the target risk level itself is based on Oregon’s 

risk management judgment. In order for the overall site-specific criterion to be “based on sound 

scientific rationale,” under 40 CFR 131.11(a)(1), it is sufficient that Oregon has clearly identified 

the rationale for the site-specific criteria as a policy decision within its discretion and consistent 

with EPA’s Human Health Methodology. 

EPA also notes that one commenter expressed concern about the interaction between the 

proposed background pollutant provision and Oregon’s existing mixing zone policy. EPA 

acknowledges that, as with other Oregon criteria, the site specific criteria generated under the 

background pollutant provision would be used in developing water quality based effluent limits 

for the NPDES permit discharging to the waterbody. EPA also acknowledges that, in certain 

instances, Oregon’s current mixing zone policy may be applied when developing such limits. In 

 Quality Standards Implementation Policies. Oregon Department of Environmental Quality. page 56. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf

152 As discussed below, Oregon’s existing mixing zone policy would still affect the calculation of effluent limits 

based on the criterion. Nevertheless, the applicable criterion in the receiving water is constrained, by OAR 340-041-

0033(6)(D), to be at least as stringent as the value calculated based on a risk level of 1x10-4. 
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the Issue Paper ODEQ states that once the site-specific background pollutant criterion has been 

determined, the criterion will be used to establish a numeric permit effluent limit using the same 

procedures and guidance used for establishing permit limits for any human health criteria.153 

Furthermore, ODEQ’s response to comments specifies that any mixing will be determined based 

on the guidance provided in [O]DEQ’s Reasonable Potential Internal Management Directive 

(IMD) and that [O]DEQ’s published guidelines (Regulated Mixing Zones IMD) would govern 

the siting and sizing of any zones of mixing.154 Any mixing zone allowed would be required 

under the CWA to comply with the all requirements of the State’s mixing zone provision prior to 

a mixing zone being authorized. In certain circumstances it is possible that a mixing zone for a 

site-specific criterion generated under this provision (or any other human health criterion for a 

carcinogen) may allow a limited area of the waterbody in which the cancer risk associated with 

the pollutant concentration would exceed 1 × 10-4. However, EPA does not therefore conclude 

that the criterion is inconsistent with its Human Health Methodology. The potential for criteria 

to be implemented in concert with an EPA-approved state mixing zone policy is a background 

assumption of EPA’s Human Health Methodology, not an additional factor that would weigh in 

favor of further limiting states’ risk management discretion. 

Furthermore, the language of OAR 340-041-0033(6)(d)(A) and (B) that speaks to the projected 

instream concentration “after mixing with the receiving stream” addresses the calculation of a 

projected instream value under specified effluent conditions. It does not establish a new mixing 

zone policy. EPA finds it appropriate that ODEQ utilize calculations similar to those used to 

develop permits when projecting this instream value as this allows the results of applying 

limitations to the effluent to be expressed as an insteam concentration and thus to be directly 

compared to the options limited by instream concentration. Furthermore, it provides that, for 

purposes of the stringency analysis, all options are expressed in the same units as the final 

criterion value. A similar practice is commonly used when EPA and States determine whether a 

discharge needs a water quality based effluent limit (see, e.g., 40 CFR 122.44(d)(1)(ii) “When 

determining whether a discharge causes, has the reasonable potential to cause, or contributes to 

an in-stream excursion above a narrative or numeric water quality standard, the permitting 

authority shall use procedures which account for ... where appropriate, the dilution of the 

effluent in the receiving water.” (emphasis added)). 

EPA considered whether implementation of the background pollutant provision is consistent 

 

153 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. page 60. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf

154 ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 

Quality Standards Implementation Policies. Oregon Department of Environmental Quality. page 55. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf

ODEQ. August 2011. Internal Management Directive: Reasonable Potential Analysis Process for Toxic Pollutants, 

Version 3.0. Oregon Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/pubs/imds/rpaIMD.pdf 

ODEQ. December 2007. Oregon Department of Environmental Quality. Regulatory Mixing Zone Internal 

Management Directive. Part 1: Allocating Regulatory Mixing Zones. Available at: 

http://www.deq.state.or.us/wq/pubs/imds/rmz/RMZIMDpart1.pdf and Regulatory Mixing Zone Internal 

Management Directive. Part 2: Reviewing Mixing Zone Studies. Available at: 

http://www.deq.state.or.us/wq/pubs/imds/rmz/RMZIMDpart2.pdf 
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with the requirements of 40 CFR 131.10. For the following reasons, EPA concludes that it is. 

Oregon has expressly stated that a criterion based on a higher risk level, established pursuant to 

the provision, “continues to protect human health.” OAR 340-041-0033(6). Thus, the 

background pollutant provision does not represent the revision of a human health use, but rather 

the articulation (within the range of the state’s discretion) of the risk range the State considers 

protective of human health uses in this site-specific situation. The revision of criteria within the 

State’s range of discretion for a designated use does not represent the removal or impairment of 

such a designated use. In conclusion, the provision contains a clear, predictable and transparent 

restriction that any site-specific criterion to be generated under the background pollutant 

provision must not correspond to a human health risk level of less stringent than 1 × 10-4.

155 

This minimum risk level is the most critical of the restrictions contained in the provision since it 

sets the least stringent criterion possible under the procedure. The least stringent criterion 

possible under the procedure is protective of Oregon’s human health uses and is consistent with 

EPA’s Human Health Methodology. Thus, EPA’s approval of the provision may also serve as 

the Clean Water Act § 303(c)(3) approval of the individual site-specific criteria to be generated 

under the provision. 

The provision generates site-specific human health criteria consistent with 40 CFR 131.11 

EPA’s regulations at 40 CFR 131.11 require States to adopt water quality criteria that protect the 

designated use and must be that are based on sound scientific rationale. It also allows States to 

modify criteria in order to reflect site-specific situations.156 In OAR 340-041-0033(6) Oregon 

establishes a procedure to develop a site-specific human health criterion for carcinogens in a 

limited number of site-specific situations when developed consistent with the procedures 

specified in the rule. 

Oregon has restricted the use of the site-specific background pollutant criteria provision to 

waterbodies where an existing NPDES discharger withdraws water from a waterbody and returns 

it to the same waterbody without adding any mass to the pollutant of concern. It is further 

limited to carcinogenic pollutants157 and utilizes information about the discharge to limit the 

criterion. The rule provides a structured framework for developing a site-specific criterion which 

is limited by a number of factors, including a requirement that the criterion never exceed a 

criterion calculated at a 1 x 10-4 risk level. Further limitations are derived based on the preexisting quantity and quality of the discharge into the receiving water, no greater than a three 

percent increase in instream concentration and no increase in mass load of the pollutant from the 

discharger. In no case will the criteria allow greater than a 10-4 carcinogenic risk level (as 

established using the same methodology used for all other human health criteria addressed in this 

action).

EPA has reviewed whether Oregon had supplied appropriate grounds to derive a site-specific 

human health criterion for carcinogens, consistent with 40 CFR 131.11. EPA’s water quality 

standards regulations provide that water quality criteria “must be based on sound scientific 

 

155 OAR 340-041-0033(6)(d) 156 40 CFR 131.11 (A)(1); 40 CFR 131.11(b)(1)(ii) 157 OAR 340-041-0033(6)(b)(A)
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rationale,”158 and contemplate that a State may adopt site-specific criteria, and provide that these 

site-specific criteria “should . . . reflect site-specific conditions.”159 EPA’s Human Health 

Methodology further clarifies a State’s flexibility to derive site-specific criteria for human health 

criteria. Human health criteria may be modified to reflect, in a justifiable manner, “local 

environmental conditions.” Local conditions may be those which prevail over a particular river 

reach, an entire river, regionally, or Statewide.160 In other guidance, EPA has acknowledged 

that less stringent site specific modifications to human health criteria may be appropriate (in that 

case, either based on local variation in fish consumption rates or applicable bioaccumulation 

factors).161 Thus, EPA finds that the criteria are based on a sound scientific rationale, will 

reflect site-specific conditions and, as discussed above, are established at a level that will protect 

Oregon’s human health uses.

The provision establishes site-specific human health criteria using the performance-based 

criterion approach

Finally, EPA reviewed whether the background pollutant provision contains sufficient detail, and 

suitable safeguards, that EPA’s approval of the provision may also serve as the Clean Water Act 

§ 303(c)(3) approval of the individual site-specific criteria to be generated under the provision. 

EPA’s water quality standard regulations at 40 CFR 131.21 provide that a state water quality 

standard adopted after May 30, 2000 is not applicable for Clean Water Act purposes until “EPA 

approves that water quality standard [under § 303(c)(3) of the CWA].” However, when EPA 

promulgated this regulation it made clear that states have the option to streamline this process by 

pursuing a “performance-based” approach whereby the state adopts a “process (i.e., a criterion 

derivation methodology) rather than a specific outcome (i.e., concentration limit for a pollutant) 

consistent with 40 CFR 131.11 and 131.13.”162 Under the performance-based approach, EPA 

conducts a CWA § 303(c)(3) review of the procedure and the criteria that would be generated 

under that procedure. EPA approval of the provision can encompass approval of the individual 

criteria to be generated under the provision where the procedure is “sufficiently detailed and has 

suitable safeguards to ensure predictable and repeatable outcomes.” To this end, the procedure 

should establish a “structure or decision-making framework that is binding, clear, predictable, 

and transparent.” 163 EPA further specified that the performance-based approach is particularly 

well suited to the derivation of site-specific numeric criteria where the proper construction and 

implementation of such an approach can result in defensible site-specific adjustments to numeric 

ambient water quality criteria.164

 

158 40 CFR 131.11(a) 

159 40 CFR 131.11(b) 160 EPA. 2000. Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. U.S. 

Environmental Protection Agency, Office of Water, EPA-822-B-00-004. pages 2-13. Available at: 

http://www.epa.gov/waterscience/criteria/humanhealth/method/complete.pdf

161 40 CFR 132 App. F., Proc. 1, A. 4 162 April 27, 2000. Federal Register, Volume: 65, No.: 82, page: 24648 (65 FR 24648). Available at: 

http://www.gpo.gov/fdsys/pkg/FR-2000-04-27/pdf/00-8536.pdf 163 April 27, 2000. Federal Register, Volume: 65, No.: 82, page: 24648 (65 FR 24648). Available at: 

http://www.gpo.gov/fdsys/pkg/FR-2000-04-27/pdf/00-8536.pdf 164 April 27, 2000. Federal Register, Volume: 65, No.: 82, page: 24648 (65 FR 24648). Available at: 

http://www.gpo.gov/fdsys/pkg/FR-2000-04-27/pdf/00-8536.pdf
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Oregon’s site-specific background pollutant criterion provision was adopted as a performancebased approach to develop site-specific human health criteria for carcinogens under the 

conditions and procedures specified in their rule.165 Oregon’s July 21, 2011 submission letter 

specifically states that the provision was “adopted [as] a new performance-based water quality 

standard” and that it “establishes the procedure by which a site-specific criterion may be 

developed for a limited portion of the waterbody”.166 ODEQ’s staff report EQC at the time of 

rule adoption indicates a clear intent for the rule to be adopted as a procedure by which, when 

approved by EPA, could be used to develop site-specific criteria that will not need subsequent 

approval by EPA.167 

A performance-based approach relies on the State to specify methodologies and decision 

thresholds in their water quality standards regulations so that a structure or decision-making 

framework that is binding, clear, predictable and transparent is established. As with all other 

modifications to state water quality standards, EPA requires that the state provide opportunity for 

the public to comment on this rule and that the regulation be adopted consistent with state law. 

Oregon’s site-specific pollutant criterion provision has been promulgated in OAR 340-041-

0033(6) of Oregon’s Water Quality Standards, has undergone public review and hearing through 

the process used for all other revisions adopted by the State on June 16, 2011, and has been 

certified as having been adopted pursuant to State law.168 Therefore, EPA finds that this 

provision provides a regulatory framework for decision-making (i.e. criteria development) that is 

binding, predictable and transparent and that the public has had the opportunity to provide 

comment on the proposed rule. 

EPA’s guidance further notes that a performance-based “approach is particularly useful for 

criteria which are heavily influenced by site-specific factors.”169 In this case, Oregon has 

restricted the use of this provision to waterbodies where a waterbody contains a pollutant 

upstream of a water supply source and a NPDES discharger withdraws water from the waterbody 

and returns it to the same waterbody without adding any mass to the pollutant of concern. 

Additionally, the background pollutant provision

 

165 OAR 340-041-0033(6)

specifies that it only applies to carcinogenic 

pollutants, OAR 340-041-0033(6)(b)(A), and utilizes information about the discharge to limit the 

criterion. Thus, EPA believes it is appropriate that such criterion be developed on a site-specific 

basis. 

166 ODEQ. July 21, 2011. Letter from Neil Mullane, Water Quality Division Administrator, to Michael Bussell, 

Office of Water and Watersheds, EPA Region 10. Re: Oregon Submission of Revised State Water Quality 

Standards for Toxic Pollutants, Including a New Background Pollutant Provision and a Revised Variance Rule for 

EPA Review and Approval. 

167 ODEQ. June 2, 2011. Memorandum from Dick Pedersen to Environmental Quality Commission; Agenda item C, 

Rule adoption: Revised water quality standards for human health and revised water quality standards 

implementation policies, June 15-17, EQC meeting. Oregon Department of Environmental Quality. page 11. 

Available at: http://www.deq.state.or.us/about/eqc/agendas/attachments/2011june/C-WQStdsStaffRpt.pdf 168 Oregon Department of Justice. General Counsel Division. July 20, 2011. Letter from Larry Knudsen, Assistant 

Attorney General, Natural Resources Section, to Michael Bussell, EPA Region 10. Re: Certification of Water 

Quality Standard Amendment (Fish Consumption Rate).

169 April 27, 2000. Federal Register, Volume: 65, No.: 82, page: 24648 (65 FR 24648). Available at: 

http://www.gpo.gov/fdsys/pkg/FR-2000-04-27/pdf/00-8536.pdf
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Finally, EPA’s guidance specifies that such procedures “must include a public participation step 

to provide all stake-holders and the public an opportunity to review the data and calculations 

supporting the site-specific application of the implementation procedures.” The State would also 

need to maintain a publically available, comprehensive list of all site-by-site decisions made 

using the procedures.170 Oregon’s WQS regulation at OAR 340-041-0033(6)(i) establishes the 

public notification requirements for any criterion to be adopted under this provision. It 

specifically requires ODEQ to provide public notice of the proposal and hold a public hearing. 

In addition to other public notification procedures in place by the State, ODEQ will publish the 

proposal on their WQS website. Furthermore, the provision requires ODEQ to publish a list of 

all criteria approved pursuant to the rule within 30 days of its effective date and identifies the 

minimum elements to be contained in this list. EPA believes that the public process required by 

Oregon within OAR 340-041-0033(6)(i) is consistent with that described in EPA’s guidance and 

required by 40 CFR 131.11. 

In order to provide further guidance to ODEQ staff and to ensure consistent implementation of 

the provision, ODEQ will develop an Internal Management Directive (guidance document) 

within 180 days of EPA’s action on this provision.171 This document will be available on 

ODEQ’s website and thus facilitate even greater clarity and transparency for the public.

In consideration of the above factors, EPA concludes that the provision contains a binding, clear, 

predictable, and transparent framework such that any site-specific criterion generated under the 

provision must not result in a human health risk level of greater than 1 × 10-4 and will protect the 

human health uses of Oregon’s waters. Therefore, any additional oversight by EPA would be 

redundant. Thus, the provision contains sufficient detail, and suitable safeguards, that EPA’s 

approval of the provision serves as the Clean Water Act § 303(c)(3) approval of the individual 

site-specific criteria to be generated under the provision. Since this procedure is adopted into 

State regulation and Oregon is bound by the decision-making framework contained therein, any 

criteria which are not derived in accordance with the approved procedures would need separate 

approval from EPA to be applicable under the CWA. 

When EPA reviews the results of Oregon’s triennial review, EPA expects to evaluate a 

representative subset of the site-specific decisions to ensure that Oregon is adhering to the EPAapproved procedure. Finally, EPA notes that if Oregon fails to follow these procedures and does 

not obtain separate CWA § 303(c)(3) approval for the site-specific criterion, this would provide 

EPA with a basis to object to an NPDES permit for not deriving from or complying with the 

applicable standards.172

 

170 April 27, 2000. Federal Register, Volume: 65, No.: 82, page: 24648 (65 FR 24648). Available at: 

 

http://www.gpo.gov/fdsys/pkg/FR-2000-04-27/pdf/00-8536.pdf 171 ODEQ. June 2, 2011. Memorandum from Dick Pedersen to Environmental Quality Commission; Agenda item C, 

Rule adoption: Revised water quality standards for human health and revised water quality standards 

implementation policies, June 15-17, EQC meeting. Oregon Department of Environmental Quality. Supplemental 

Attachment 10, Timeline for Follow-Up Actions, WQS for Human Health Toxic Pollutants Rulemaking. 172 40 CFR 122.44(d)

April 27, 2000. Federal Register, Volume: 65, No.: 82, page: 24648 (65 FR 24648). Available at: 

http://www.gpo.gov/fdsys/pkg/FR-2000-04-27/pdf/00-8536.pdf
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VII. VARIANCE PROVISION

A. BACKGROUND

EPA’s regulations at 40 C.F.R. Part 131.13, provides that states may, at their discretion, include 

in state water quality standards policies generally affecting the application and implementation of 

water quality standards, such as general policies for variances. If a state chooses to adopt such a 

variance policy, the regulation specifies that such policies are required to be submitted to EPA 

for review and approval. 

The objective of the Clean Water Act is to restore and maintain the chemical, physical and 

biological integrity of the Nation’s waters. The CWA further specifies an interim goal that, 

“wherever attainable,” water quality provides for the protection and propagation of fish, 

shellfish, and wildlife and provides for recreation in and on the water. 

40 C.F.R. Part 131.10(g) specifies the factors a state may use to determine that a designated use, 

which is not an existing use, is not ultimately attainable. These factors are: 

1. Naturally occurring pollutant concentrations prevent the attainment of the use; or 

2. Natural, ephemeral, intermittent or low flow conditions or water levels prevent the 

attainment of the use, unless these conditions may be compensated for by the 

discharge of sufficient volume of effluent discharges without violating state water 

conservation requirements to enable uses to be met; or

3. Human caused conditions or sources of pollution prevent the attainment of the use 

and cannot be remedied or would cause more environmental damage to correct than 

to leave in place; or

4. Dams, diversions or other types of hydrologic modifications preclude the attainment 

of the use, and it is not feasible to restore the water body to its original condition or to 

operate such modification in a way that would result in the attainment of the use; or

5. Physical conditions related to the natural features of the water body, such as the lack 

of a proper substrate, cover, flow, depth, pools, riffles, and the like, unrelated to water 

quality, preclude attainment of aquatic life protection uses; or 

6. Controls more stringent than those required by sections 301(b) and 306 of the Act 

would result in substantial and widespread economic and social impact. 

In 1977, an Office of General Counsel legal opinion173 considered the practice of temporarily 

downgrading the designated use and criteria, as it applies to a specific discharger rather than 

permanently174

 

173 EPA. March 29, 1977. Office of General Counsel on Matters of Law Pursuant to 40 CFR Section 125.36(m). 

No. 58. U.S. Environmental Protection Agency. Washington, D.C. Available at: 

 downgrading an entire water body or water body segment and determined that 

http://water.epa.gov/scitech/swguidance/standards/upload/2008_08_04_standards_section40cfr3.pdf 174 “Permanent” used in the context of a designated use is intended solely to differentiate from a time-limited 

variance. EPA’s regulations at 131.20 require states to review uses that do not include those specified in CWA 

section 101(a)(2) and to revise standards accordingly if information becomes available to indicate such uses are 

attainable.
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such a practice is acceptable as long as it is adopted consistent with the substantive requirements 

for permanently downgrading a designated use. EPA continued to articulate this position in its 

Water Quality Standards Handbook (Section 5.3) specifically stating: 

Variance procedures involve the same substantive and procedural requirements as 

removing a designated use , but unlike use removal, variances are both discharger and 

pollutant specific, are time limited, and do not forego the currently designated use. 

Thus, the six 131.10(g) factors, which are used to justify a designated use change through a use 

attainability analysis, consistent with 131.10(g), are the same factors that must be evaluated 

when justifying a variance. 

Variances allow for a more site-specific and time-limited consideration of attainability than a 

permanent designated use revision. They encourage states to maintain the underlying designated 

uses and criteria as goals instead of declaring them unattainable prematurely when they may be 

attainable in the long term. For example, technology improvements could lower treatment costs 

in the future such that attaining the designated use and criteria would no longer cause substantial 

and widespread economic and social impact. Variances are typically specific to a pollutant(s) and 

either apply to specific permittees or geographic areas. Variances only apply to the pollutants, 

permittees and geographic areas for which they were written; all other applicable standards 

remain in place. 

Variances must be of a limited or temporary duration for a fixed term.175 Variances are timelimited designated uses and associated criteria and are thus considered water quality standards. 

As such, any variances granted by the state must be submitted to EPA for review and approval or 

disapproval under CWA section 303(c). The preamble to EPA’s 1983 regulation176 states that 

EPA has approved state-adopted variances in the past and will continue to do so if each 

individual variance is adopted as a water quality standard and subject to the same public review 

as other changes in the water quality standards. EPA’s Water Quality Standards Handbook177

reiterates the 1983 Preamble as did EPA’s Advanced Notice of Proposed Rulemaking 

(ANPRM), in 1998, seeking comments on possible revisions to the Water Quality Standards 

Regulation.178 

EPA’s Water Quality Standards Handbook also specifies that EPA has approved state-adopted 

variances in the past and will continue to do so if: 

 

175 EPA. January 24, 1992. Office of General Counsel Memorandum Re: Request for Views on Allowable Duration 

of Water Quality Standards Variances. U.S. Environmental Protection Agency. Catherine A Winer, Attorney. 

Available at: http://water.epa.gov/scitech/swguidance/standards/upload/1999_11_03_standards_variancememo.pdf 176 November 8, 1983. Federal Register, Volume: 48, No.: 217, page 51403 (48 FR 51403). Available at: 

http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=20003ZVR.txt 177 EPA. 1994. Water Quality Standards (WQS) Handbook: Second Edition. August 1994. United States 

Environmental Protection Agency, Office of Water. EPA-823-B-94-005a. page 5-12. Available at 

http://water.epa.gov/scitech/swguidance/standards/handbook/index.cfm

178 July 7, 1998. Federal Register, Volume: 63, No.: 129, page: 36759 (63 FR 36759). Available at: 

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• The State includes the individual variance as part of the water quality standard.

• The state demonstrates that meeting the standard is unattainable based on one or more of 

the factors in 131.10(g). 

• The justification submitted includes documentation that treatment more advanced than 

that required by sections 301(b)(1)(b) and 306 of the Clean Water Act has been carefully 

considered and that alternative effluent control strategies have been evaluated.

• The more stringent State criterion is maintained and is binding upon all other dischargers 

on the stream or stream segment.

• The discharger who is given a variance for one particular constituent is required to meet 

the applicable criteria for other constituents. 

• The variance was granted for a specific period of time.

• The discharger either must meet the standard upon the expiration of this time period or 

must make a new demonstration of “unattainability.”

• Reasonable progress is being made toward meeting the water quality standards.

• The variance was subjected to public notice and opportunity for comment. 

In summary, states have the discretion to include variance policies in their water quality 

standards regulation. Such policies are subject to EPA review and approval. In addition, if a 

state chooses to revise standards by granting a variance, states must adopt such variances 

pursuant to state law and each individual variance is subject to public review, consistent with 

EPA’s regulations. Variances are not effective for Clean Water Act purposes until approved by 

EPA. 

B. ODEQ’S JULY 21, 2011 SUBMITTAL

ODEQ has removed the variance language found at OAR 340-041-0061(2) and replaced it with 

new language at OAR 340-041-0059. Oregon’s revised variance provision lays out the 

necessary process for obtaining a variance, the conditions under which a variance will be 

granted, and the requirements during a variance. DEQ’s objective for these revisions is to ensure 

that variances and their accompanying pollutant reduction plans continue to ensure progress 

toward meeting standards, to streamline the administration process, to require pollutant reduction 

plans with specific milestones that will result in water quality improvement, and to add general 

clarification to the rule.179

Below is ODEQ’s revised variance provision, found at OAR 340-041-0059. 

OAR 340-041-0059 

Variances 

This rule (OAR 340-041-0059) does not become applicable for purposes of ORS chapter 468B or the 

federal Clean Water Act unless and until EPA approves the provisions it identifies as water quality 

 

179 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf
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standards pursuant to 40 CFR 131.21 (4/27/2000). 

 (1) Applicability. Subject to the requirements and limitations set out in sections (2) through (7) below, a 

point source may request a water quality standards variance where it is demonstrated that the source 

cannot feasibly meet effluent limits sufficient to meet water quality standards. The director of the 

department will determine whether to issue a variance for a source covered by an existing NPDES 

permit. The commission will determine whether to issue a variance for a discharger that does not have a 

currently effective NPDES permit.

(a) The variance applies only to the specified point source permit and pollutant(s); the underlying 

water quality standard(s) otherwise remains in effect.

(b) The department or commission may not grant a variance if: 

(A) The effluent limit sufficient to meet the underlying water quality standard can be 

attained by implementing technology-based effluent limits required under sections 301(b) 

and 306 of the federal Clean Water Act, and by implementing cost-effective and 

reasonable best management practices for nonpoint sources under the control of the 

discharger; or

(B) The variance would likely jeopardize the continued existence of any threatened or 

endangered species listed under section 4 of the Endangered Species Act or result in the 

destruction or adverse modification of such species' critical habitat; or 

(C) The conditions allowed by the variance would result in an unreasonable risk to 

human health; or 

(D) A point source does not have a currently effective NPDES permit, unless the variance 

is necessary to:

(i) Prevent or mitigate a threat to public health or welfare; 

 

(ii) Allow a water quality or habitat restoration project that may cause short 

term water quality standards exceedances, but will result in long term water 

quality or habitat improvement that enhances the support of aquatic life uses;

(iii) Provide benefits that outweigh the environmental costs of lowering water 

quality. This analysis is comparable to that required under the antidegradation 

regulation contained in OAR-041-0004(6)(b); or 

(E) The information and demonstration submitted in accordance with section (4) below 

does not allow the department or commission to conclude that a condition in section (2) 

has been met. 

(2) Conditions to Grant a Variance. Before the commission or department may grant a variance, it must 

determine that:

(a) No existing use will be impaired or removed as a result of granting the variance and\ 

(b) Attaining the water quality standard during the term of the variance is not feasible for one or 
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more of the following reasons:

(A) Naturally occurring pollutant concentrations prevent the attainment of the use; 

(B) Natural, ephemeral, intermittent, or low flow conditions or water levels prevent the 

attainment of the use, unless these conditions may be compensated for by the discharge of 

sufficient volume of effluent discharges to enable uses to be met without violating state 

water conservation requirements;

(C) Human-caused conditions or sources of pollution prevent the attainment of the use 

and cannot be remedied or would cause more environmental damage to correct than to 

leave in place;

(D) Dams, diversions, or other types of hydrologic modifications preclude the attainment 

of the use, and it is not feasible to restore the waterbody to its original condition or to 

operate such modification in a way which would result in the attainment of the use; 

(E) Physical conditions related to the natural features of the waterbody, such as the lack 

of a proper substrate, cover, flow, depth, pools, riffles, and unrelated to water quality 

preclude attainment of aquatic life protection uses; or 

(F) Controls more stringent than those required by sections 301(b) and 306 of the federal 

Clean Water Act would result in substantial and widespread economic and social impact.

(3) Variance Duration. 

(a) The duration of a variance must not exceed the term of the NPDES permit. If the permit is 

administratively extended, the permit effluent limits and any other requirements based on the 

variance and associated pollutant reduction plan will continue to be in effect during the period of 

the administrative extension. The department will give priority to NPDES permit renewals for 

permits containing variances and where a renewal application has been submitted to the director 

at least one hundred eighty days prior to the NPDES permit expiration date. 

(b) When the duration of the variance is less than the term of a NPDES permit, the permittee must 

be in compliance with the specified effluent limitation sufficient to meet the underlying water 

quality standard upon the expiration of the variance. 

(c) A variance is effective only after EPA approval. The effective date and duration of the 

variance will be specified in a NPDES permit or order of the commission or department.

(4) Variance Submittal Requirements. To request a variance, a permittee must submit the following 

information to the department: 

(a) A demonstration that attaining the water quality standard for a specific pollutant is not 

feasible for the requested duration of the variance based on one or more of the conditions found 

in section (2)(b) of this rule; 

(b) A description of treatment or alternative options considered to meet limits based on the 

applicable underlying water quality standard, and a description of why these options are not 

technically, economically, or otherwise feasible;
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(c) Sufficient water quality data and analyses to characterize ambient and discharge water 

pollutant concentrations; 

(d) Any cost-effective and reasonable best management practices for nonpoint sources under the 

control of the discharger that addresses the pollutant the variance is based upon; 

(e) A proposed pollutant reduction plan that includes any actions to be taken by the permittee that 

would result in reasonable progress toward meeting the underlying water quality standard. Such 

actions may include proposed pollutant offsets or trading or other proposed pollutant reduction 

activities, and associated milestones for implementing these measures. Pollutant reduction plans 

will be tailored to address the specific circumstances of each facility and to the extent pollutant 

reduction can be achieved; and

(f) If the discharger is a publicly owned treatment works, a demonstration of the jurisdiction’s 

legal authority (such as a sewer use ordinance) to regulate the pollutant for which the variance is 

sought. The jurisdiction’s legal authority must be sufficient to control potential sources of that 

pollutant that discharge into the jurisdiction’s sewer collection system.

(5) Variance Permit Conditions. Effluent limits in the discharger's permit will be based on the variance 

and not the underlying water quality standard, so long as the variance remains effective. The department 

must establish and incorporate into the discharger’s NPDES permit all conditions necessary to 

implement and enforce an approved variance and associated pollutant reduction plan. The permit must 

include, at a minimum, the following requirements: 

(a) An interim concentration based permit limit or requirement representing the best achievable 

effluent quality based on discharge monitoring data and that is no less stringent than that 

achieved under the previous permit. For a new discharger, the permit limit will be calculated 

based on best achievable technology;

(b) A requirement to implement any pollutant reduction actions approved as part of a pollutant 

reduction plan submitted in accordance with section (4)(e) above and to make reasonable 

progress toward attaining the underlying water quality standard(s); 

(c) Any studies, effluent monitoring, or other monitoring necessary to ensure compliance with the

 conditions of the variance; and 

(d) An annual progress report to the department describing the results of any required studies or 

monitoring during the reporting year and identifying any impediments to reaching any specific 

milestones stated in the variance. 

(6) Public Notification Requirements. 

(a) If the department proposes to grant a variance, it must provide public notice of the proposal 

and hold a public hearing. The public notice may be included in the public notification of a draft 

NPDES permit or other draft regulatory decision that would rely on the variance; 

(b) The department will publish a list of all variances approved pursuant to this rule. Newly 

approved variances will be added to this list within 30 days of their effective date. The list will 

identify: the discharger; the underlying water quality standard addressed by the variance; the 

waters of the state to which the variance applies; the effective date and duration of the variance; 
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the allowable pollutant effluent limit granted under the variance; and how to obtain additional 

information about the variance.

(7) Variance Renewals.

(a) A variance may be renewed if: 

(A) The permittee makes a renewed demonstration pursuant to section (2) of this rule that 

attaining the water quality standard continues to be infeasible,

(B) The permittee submits any new or updated information pertaining to any of the 

requirements of section 4,

(C) The department determines that all conditions and requirements of the previous 

variance and actions contained in the pollutant reduction plan pursuant to section (5) 

have been met, unless reasons outside the control of the discharger prevented meeting 

any condition or requirement, and 

(D) All other requirements of this rule have been met.

(b) A variance renewal must be approved by the department director and by EPA. 

C. EPA ACTION ON ODEQ’S REVISED VARIANCE PROVISION

EPA Action

In accordance with its CWA authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, EPA 

approves certain sections of Oregon’s revised variance provision at OAR 340-041-0059, as 

detailed below, because they are consistent with the Clean Water Act and the implementing 

Federal water quality standards regulations governing EPA’s review and approval or disapproval 

of new or revised water quality standards as required in 40 C.F.R. part 131. These federal 

regulations as well as EPA’s guidance, to date, on variances are detailed above. EPA outlines 

below the sections of the provision it is approving as water quality standards pursuant to CWA 

section 303(c) and the sections of the provision which are not water quality standards under 

CWA section 303(c) and therefore upon which EPA is taking no action. Oregon may use the full 

variance provision (both those sections approved as WQS and those identified as not being 

WQS) when developing and implementing any individual variance. Each individual variance the 

State adopts consistent with the regulations at OAR 340-041-0059, must be submitted to EPA for 

review and approval prior to its use in a NPDES permit or other CWA action. In EPA’s review 

of Oregon’s revised variance provision, the Agency considered information submitted on July 

21, 2011 including ODEQ’s NPDES Implementation Issue Paper180 and Response to Comments 

document.181

 

180 ODEQ. May 24, 2011. Issue Paper: Implementing Water Quality Standards for Toxic Pollutants in NPDES 

Permits, Human Health Toxics Rulemaking. Oregon Department of Environmental Quality. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/NPDESIssuePaper.pdf 181 ODEQ. May 2011. Response to Comments: Proposed Water Quality Standards for Human Health and Water 

Quality Standards Implementation Policies. Oregon Department of Environmental Quality. page 21. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ResponseToComments.pdf
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EPA Rationale

EPA has reviewed the provision at OAR 340-041-0059 in Oregon’s water quality standards 

regulations, entitled, “Variances”. EPA previously approved Oregon’s existing variance 

provision at OAR 350-041-0061(2). 

Oregon’s revised variance provision adds more definition to what was required in OAR 350-041-

0061(2) and requires the applicant to develop a schedule for improvements by implementing a 

pollution reduction plan. These revisions will assist in meeting the goal of facilitating water 

quality improvements and attaining the underlying criteria. 

EPA is approving the specified sections of Oregon’s variance regulation explained below as a 

“general policy” under §131.13. ODEQ is still required to submit each individual variance to 

EPA for review and action before it is effective for purposes of the CWA because the variances 

themselves are also water quality standards. Accordingly, each variance submitted for EPA’s 

review must include the Attorney General’s certification and be consistent with the CWA and 

EPA’s implementing regulations, including all applicable public participation requirements. 

Thus, EPA’s review of Oregon’s variance authorizing provision need not evaluate each 

hypothetical variance the State may issue under OAR 340-041-0059 and consider whether such a 

variance would be consistent with the CWA and EPA’s implementing regulation. EPA’s 

approval of Oregon’s variance provision at OAR 340-041-0059 is not an automatic approval of 

any future variance the State wishes to grant pursuant to these provisions. 

Below, EPA outlines the sections it is approving as water quality standards pursuant to CWA 

section 303(c) and the sections upon which EPA is taking no action. EPA’s approval reflects 

EPA’s determination that the specific section adopted at OAR 340-041-0059 is consistent with 

the Clean Water Act and the implementing Federal water quality standards regulations in 40 

C.F.R. part 131. 

Introductory Language to OAR 340-041-0059 

EPA is approving the introductory language which states, “This rule (OAR 340-041-0059) does 

not become applicable for purposes of ORS chapter 468B or the federal Clean Water Act unless 

and until EPA approves the provisions it identifies as water quality standards pursuant to 40 CFR 

131.21 (4/27/2000).” 

In accordance with its Clean Water Act authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, 

EPA approves this new language. This language describes when Oregon’s revised variance 

provision becomes effective under state law and the Clean Water Act. The effective date of 

water quality standards provisions under the CWA is determined by the date of EPA approval. 

This language regarding timing is a water quality standard that provides for the sections of the 

revised variance provision to be immediately in effect at the time of EPA’s approval action. 

OAR 340-041-0059(1) “Applicability” 

EPA is approving OAR 340-041-0059(1) “Applicability” and OAR 340-041-0059(1)(a) which 

reflects that the variance only applies to the specified point source and pollutant; the underlying 

water quality standards remain in effect. This scope of applicability is consistent with EPA 

interpretive Guidance and the 1977 Office of General Counsel legal opinion discussing 
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variances. 

Moreover, EPA is approving OAR 340-041-0059(1)(b) and (1)(b)(A) as they are consistent with 

131.10(h)(2) which prohibits a State’s removal of a designated uses where “[s]uch uses will be 

attained...by implementing cost-effective and reasonable best management practices for 

nonpoint source control.” EPA has concluded that Oregon’s language at (1)(b)(A) that prohibits 

the State from issuing a variance where “effluent limitations sufficient to meet the underlying 

water quality standards can be attained by...implementing cost-effective and reasonable best 

management practices for nonpoint sources under the control of the discharger,” is consistent 

with 131.10(h)(2) because Oregon’s variance authorizing provision only allows the State to issue 

discharger-specific variances.182 Given this scope of Oregon’s variance authorizing provision, 

EPA believes it is reasonable for the State to limit the prohibition in (1)(b)(A) to those costeffective and reasonable best management practices for nonpoint sources to those practices under 

the control of the discharger.183

EPA is approving OAR 340-041-0059(1)(b)(B)-(E) because these sections are not inconsistent 

with the CWA and EPA’s implementing regulations. While OAR 340-041-0059(1)(b)(D) does 

not categorically prohibit the issuance of a variance to a new discharger, neither do the CWA or 

EPA’s implementing regulations. While 40 CFR 122.4(i) limits discharges from “a new source 

or a new discharger” that “will cause or contribute to the violation of water quality standards,” a 

variance is a revision to the water quality standard itself, and therefore 122.4(i) is not relevant. 

EPA notes, however, that the circumstances in which a new discharger will be able to meet the 

other requirements for a variance (e.g., a demonstration that [a]ttaining the water quality standard 

during the term of the variance is not feasible,”) are likely to be significantly more limited for a 

new discharger than an existing discharger. EPA acknowledges that granting a variance to a new 

discharger may be appropriate under very specific and limited circumstances. It will review the 

appropriateness of particular circumstances on an individual variance basis. 

 

182 OAR 340-041-0059(1)(a) provides that the “variance applies only to the specified point source permit and 

pollutant(s); the underlying water quality standard(s) otherwise remain in effect.”

183 EPA disagrees with the contrary contention, made in public comments, that the BMP requirements of 40 C.F.R. § 

131.10(h)(2) must apply to “all nonpoint sources in the consideration of a variance application, not just those under 

the control of the applicant.” Northwest Environmental Advocates (NWEA). March 17, 2011. Letter from Nina 

Bell, Executive Director, NWEA to Andrea Matzke, ODEQ, Re: Proposed Revised Water Quality Standards for 

Human Health Toxic Pollutants and Revised Water Quality Standards Implementation Policies. page 32. In support 

of this proposition, the commenter cites a 1994 EPA interpretive memorandum (“Tudor Davies memo”) and a 1995 

EPA economic guidance document. The Tudor Davies memo discusses how the requirements of 40 CFR 

131.12(a)(2) apply to antidegradation policies, not the applicability of 40 CFR 131.10(h)(2) to variances. The 

citation to the 1995 Interim Economic Guidance for Water Quality Standards is similarly inapposite. This guidance 

addresses how an economic analysis under 131.10(g)(6) should be conducted to demonstrate that a variance is 

needed. Sections 40 C.F.R. 131.10(d) and (h)(2) are independent requirements from 131.10(g). EPA recognizes 

that the introduction section of the guidance document states that polluting entities can be point or nonpoint sources 

of pollution and that attainment of water quality standards is not limited to controls placed on point sources. 

However, this statement should be viewed in context of the stated scope of the guidance, which is to address 

economic factors considered under 131.10(g) and 131.12. Even if this statement could be read to apply to 131.10(d) 

and (h)(2), Oregon’s provision at OAR 340-041-0059(1)(b)(A) is consistent with EPA’s 1995 economic guidance 

document because the guidance contemplates that financial impacts are determined by the costs the entity itself 

would face by implementing the necessary pollution controls. 
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OAR 340-041-0059(2) “Conditions to Grant a Variance”

EPA is approving OAR 340-041-0059(2), (2)(a) and (2)(b) “Conditions to Grant a Variance” 

because it is consistent with the substantive requirements of permanently changing designated 

uses at §131.10, specifically §131.10(g). 

OAR 340-041-0059(2)(a) requires the state to determine that “[n]o existing use will be impaired 

or removed as a result of granting the variance.” One commenter argues that this section is 

inconsistent with EPA’s regulations because it “does not explicitly require variances to meet the 

antidegradation policy[,]...falls short of full protection of existing uses[,]... [and] makes no 

reference to the water quality that is required to maintain and protect existing uses.”184

OAR 340-041-0059(3) “Variance Duration”

EPA is approving OAR 340-041-0059(3) and the first sentence of OAR 340-041-0059(3)(a) 

“Variance Duration” as a water quality standard that states “The duration of a variance must not 

exceed the term of the NPDES permit.” EPA understands this section to mean that each variance 

will expire five years after the State adopts the variance, the maximum length of a NPDES 

permit consistent with federal regulations and OAR 340-045-0035(8), or the variance will 

specify a specific expiration date of less than five years after the variance was adopted into state 

regulation. As discussed earlier, the 1977 Office of General Counsel legal opinion explains that 

time-limited revisions to the designated use and criteria are environmentally preferable as 

compared with the permanent removal of a designated use because the more stringent standards 

apply to all other dischargers not covered by the variance. EPA is approving this sentence as it 

states the specific time limit for which the designated use and criteria have been determined to be 

“unattainable” consistent with §131.10(g). 

EPA is taking no action on the last two sentences of OAR 340-041-0059(3)(a) “Variance 

Duration” that states “If the permit is administratively extended, the permit effluent limits and 

any other requirements based on the variance and associated pollutant reduction plan will 

continue to be in effect during the period of the administrative extension. The department will 

give priority to NPDES permit renewals for permits containing variances and where a renewal 

application has been submitted to the director at least one hundred eighty days prior to the 

 EPA 

disagrees that OAR 340-041-0059(2)(a) is inconsistent with EPA regulations. OAR 340-041-

0059(2)(a) is consistent with 131.10(h)(1) and (g) which both prohibit a state from removing the 

protection for an existing use. While a state’s adoption of new or revised water quality standards 

is not itself subject to antidegradation review, EPA notes that OAR 340-041-0059(2)(a) is also 

consistent with 131.12(a)(1): requiring the that “[e]xisting instream water uses and the level of 

water quality necessary to protect the existing uses shall be maintained and protected.” EPA 

believes that prohibiting the impairment or removal of an existing use will achieve the goals of 

“maintain[ing] and protect[ing]” the “level of water quality necessary to protect the existing 

use.” 

Section OAR 340-041-0059(2)(b) is consistent with the substantive requirements at §131.10(g). 

 

184 Northwest Environmental Advocates (NWEA). March 17, 2011. Letter from Nina Bell, Executive Director, 

NWEA to Andrea Matzke, ODEQ, Re: Proposed Revised Water Quality Standards for Human Health Toxic 

Pollutants and Revised Water Quality Standards Implementation Policies. page 39. 
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NPDES permit expiration date.” These sections are NPDES permitting requirements because 

they describe the permitting process for handling situations where there is a delay in reissuing a 

permit. Such language does not affect how long the variance applies as the approved water 

quality standard and the administrative extension of a permit is not subject to EPA WQS 

approval or disapproval. 

EPA is also taking no action on OAR 340-041-0059(3)(b) “Variance Duration” because that 

section of the provision reiterates the permitting provisions at §122.44(d)(vii) requiring the 

NPDES permit limit to derive from and comply with the applicable water quality standards once 

the variance expires. Therefore, EPA does not consider this section to be a water quality 

standard. 

EPA is approving OAR 340-041-0039(3)(c) “Variance Duration” as a water quality standard 

because it clearly states that the variance is not effective for CWA section 402 permitting 

purposes until EPA approves it, consistent with §131.21(c). EPA notes that once an individual 

variance has been approved, it is a water quality standard applicable for CWA section 402 

permitting purposes (see 40 CFR 131.21) and thus becomes subject to the triennial review 

requirements at 40 C.F.R. 131.20. 

OAR 340-041-0059(4) “Variance Submittal Requirements”

EPA is approving OAR 340-041-0059(4) “Variance Submittal Requirements” and OAR 340-

041-0059(4)(a) consistent with §131.10(g) because it requires a demonstration that one of EPA’s 

regulatory factors precludes attainment of the use. EPA is also approving OAR 340-041-

0059(4)(b)-(f) because these sections provide substantive requirements for what the applicant 

must submit to the State to obtain a variance, and are not inconsistent with the requirements of 

the CWA and EPA’s regulations. 

OAR 340-041-0059(5) “Variance Permit Conditions”

EPA is approving OAR 340-041-0059(5), (5)(a) and (5)(b) “Variance Permit Conditions” 

because these sections establish the water quality requirements during a variance. While those 

requirements might typically be presented in the form of instream water quality criteria, EPA 

considers the requirement for a permit limit to include the best achievable effluent quality to be a 

surrogate for identifying the instream water quality criteria at the highest attainable condition. 

Thus, EPA is approving sections 5(a) and 5(b) because they describe the resulting instream 

concentration and together act as a surrogate for interim criterion applicable during a variance. 

Based on Oregon’s regulatory language in this section, the best achievable effluent quality will 

be appropriately determined on a case-by-case basis. 

EPA is not taking action on OAR 340-041-0059(5)(c) and (5)(d) because they are monitoring 

and reporting requirements applicable to a discharger’s NPDES permit. These requirements are 

not considered WQS under CWA section 303(c) or addressed in EPA’s water quality standards 

regulations because they are NPDES permitting requirements. 

OAR 340-041-0059(6) “Public Notice Requirements”

EPA is approving OAR 340-041-0059(6) “Public Notice Requirements” and OAR 340-041-

0059(6)(a) and 0059(6)(b) because they address the requirements for public notice of a variance 
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consistent with §131.20(b), and explain what information will be provided to the public. EPA 

notes that this section states that public notification for a variance can be included in the public 

notification of a draft NPDES permit or draft regulatory decision that would rely on the variance. 

In addition, EPA must approve the variance before it can be implemented and thus the State 

cannot finalize the NPDES permit with a limit that reflects a variance until EPA has approved 

the variance. 

OAR 340-041-0059(7) “Variance Renewals”

EPA is approving OAR 340-041-0059(7) “Variance Renewals”. EPA is approving OAR 340-

041-0059(7)(a)(A) as consistent with 131.10(g) as it requires the permittee to demonstrate that 

attaining water quality standards during the term of the variance is still not feasible based on

factors consistent with 131.10(g)(1)-(6). EPA is approving all other language in OAR 340-041-

0059(7) because this regulatory language is not inconsistent with the CWA or EPA’s 

implementing regulations. EPA notes that since variances are water quality standards, the state 

will need to include variances in the applicable water quality standards that the state reviews 

during its triennial review processes under §131.20(a). EPA understands that OAR 340-041-

0059(7)(D) (“[a]ll other requirements of this rule have been met.”) will require a new round of 

public notice, comporting with the requirements of OAR 340-041-0059(6), and all other 

requirements in OAR 340-041-0059 to be met when any variance is renewed. 
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VIII. BACTERIA

Oregon’s revisions to its bacteria provision found at OAR 340-041-0009(10) are shown in 

underline/strikeout format below. Underlined text represents added text, while text with a line 

through the middle (strikeout) represents deleted text. The revised text corrects a citation based 

on renumbering in OAR 340-041-0061. 

(10) Water Quality Limited for Bacteria: In those water bodies, or segments of water bodies 

identified by the Department as exceeding the relevant numeric criteria for bacteria in the basin 

standards and designated as water-quality limited under section 303(d) of the Clean Water Act, 

the requirements specified in section 11 of this rule and in OAR 340-041-0061(112) must apply. 

EPA Action

In accordance with its CWA authority, 33 U.S.C § 1313(c)(3) and 40 C.F.R. part 131, EPA 

approves this minor editorial change as a non-substantive revision to water quality standards at 

OAR 340-041-0009.

EPA Rationale

The minor editorial change in this provision to correct the citation due to a renumbering revision 

in OAR 340-041-0061(12) does not alter the underlying provision that EPA previously approved 

and EPA is not acting on the underlying provision. EPA approves this non-substantive revision 

to Oregon’s WQS under section 303(c) of the CWA and the implementing regulations at 40 CFR 

Part 131. 
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IX. REVISED RULES REGARDING IMPLEMENTAIN FOR 

NONPOINT SOURCES

A. STATEWIDE NARRATIVE CRITERIA

Oregon’s revisions to OAR 340-041-0007(5) are shown in underline/strikeout format below. 

Underlined text represents added text, while text with a line through the middle (strikeout) 

represents deleted text. The revised rule clarifies the state regulatory mechanisms for water 

quality control applicable to forest management activities. 

(5) Logging and forest management activities must be conducted in accordance with the Oregon

rules established by the Environmental Quality Commission and must not cause violation of 

water quality standards. Nonpoint sources of pollution from forest operations on state and 

private forest lands are subject to best management practices and other control measures 

established by the Oregon Board of Forestry as provided in ORS 527.765 and 527.770. Forest 

Practices operations conducted in good faith compliance with the best management practices 

and control measures established under the Forest Practices Act to minimize adverse effects on 

water quality are generally deemed not to cause violations of water quality standards as 

provided in ORS 527.770. Forest operations are subject to load allocations established under 

ORS 468B.110 and OAR Division 340-042 to the extent needed to implement the federal Clean 

Water Act.

Acknowledgement of OAR 340-041-0007(5) 

EPA acknowledges the revised language contained in OAR 340-041-0007(5). ODEQ has 

revised their regulations to explain how the control measures applicable to forestry nonpoint 

sources under the Forest Practices Act are presumed to meet water quality standards and that

forest operations are subject to load allocations in TMDLs.185 Furthermore, the rule clarifies the 

water quality regulatory requirements for forest management activities in Oregon. 

This rule states that certain activities related to logging and forest management are generally 

deemed not to cause violations of water quality standards if best management practices and 

control measures under the Forest Practices Act are followed. The CWA requires NPDES 

permits for discharges from point sources and compliance with that permit, but does not require 

that states develop enforceable regulatory programs for nonpoint sources. Whether a State 

chooses to make water quality standards directly enforceable for nonpoint sources is solely a 

matter of state law and the State has discretion as to how it enforces its laws. This provision is 

applicable only to nonpoint sources and their compliance with water quality standards and 

TMDL load allocations. As such EPA does not consider this provision to be a water quality 

standard under section 303(c) of the CWA. Water quality standards are provisions of State or 

Federal law which consist of a designated use or uses for waters of the United States, and water 

quality criteria necessary to protect the uses (40 CFR 131.3(i)). 

 

185 ODEQ. June 7, 2011. Executive Summary. Human Health Toxics Rulemaking. Oregon Department of 

Environmental Quality. page 9. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ExecSummary.pdf 
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

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 In addition, this provision does not include language that has the effect of changing the level of 

protection provided by Oregon’s water quality criteria and therefore does not constitute a new or 

revised water quality standard. The provision defines how logging and forest management 

nonpoint sources activities must control their discharges in order to comply with Oregon’s water 

quality standards, but it does not establish or revise any of the components of the water quality 

standards themselves.

Therefore, this provision is not considered a water quality standard subject to EPA review and 

approval and EPA is taking no action to approve or disapprove this provision. 

B. OTHER IMPLEMENTATION OF WATER QUALITY

Oregon’s revisions to implementation provisions found at OAR 340-041-0061(9)(a)(E), (10), 

and (11) are shown in underline/strikeout format below. Underlined text represents added text, 

while text with a line through the middle (strikeout) represents deleted text. The revised rule at 

(9)(a)(E) corrects an error to the cross-reference to the antidegradation policy. The revised rules 

in (10) and (11) explain how the mechanisms for forestry and agricultural nonpoint sources work 

to meet water quality standards and the total maximum daily load (TMDL) load allocations 

under the Forest Practices Act and Agriculture Water Quality Management Act.186 Finally, the 

revised rule contains revised paragraph numbers for subsections (2) through (16) as the variance 

rule in section (2) was moved to OAR 340-041-0059. 

(9)(a)(E) Mass loads assigned as described in paragraphs (B) and (C) of this subsection will not 

be subject to OAR 340-041-0004(97);

Acknowledgement of OAR 340-041-0061(9)(a)(E)

EPA acknowledges the changed cross-reference located in OAR 340-041-0061(9)(a)(E) Other 

Implementation of Water Quality Criteria. Water quality standards are provisions of State or 

Federal law which consist of a designated use or uses for waters of the United States, and water 

quality criteria necessary to protect the uses (40 CFR 131.3(i)). EPA has determined this 

provision is not a WQS. Instead, the provision at section (9)(a)(E) is a NPDES permitting

implementation provision and corrects an error to a regulatory citation to the antidegradation 

policy. 

(10) Forestry on state and private lands. For Nonpoint sources of pollution from forest 

operations on state or private lands, water quality standards are intended to be attained and are 

implemented through subject to best management practices and other control mechanisms

measures established under the Forest Practices Act (ORS 527.610 to 527.992) and rules 

thereunder, administered by the Oregon Department of Forestry. Therefore, under the Forest 

Practices Act, (ORS 527.610 to 527.992) Such forest operations that are when conducted in 

good faith compliance with the Forest Practices Act requirements are (except for the limits set 

out in ORS 527.770) deemed in compliance with this division. DEQ will work with the Oregon 

 

186 ODEQ. June 7, 2011. Executive Summary. Human Health Toxics Rulemaking. Oregon Department of 

Environmental Quality. page 9. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ExecSummary.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

102

Department of Forestry to revise the Forest Practices program to attain water quality standards. 

generally deemed not to cause violations of water quality standards as provided in ORS 527.770. 

Forest operations on state and private lands are subject to load allocations under ORS 468.110 

and OAR 340, Division 42, to the extent necessary to implement the federal Clean Water Act.

(11) Agricultural water quality management plans to reduce agricultural nonpoint source 

pollution are developed and implemented by the Oregon Department of Agriculture (ODA) 

through a cooperative agreement with the department to implement applicable provisions of 

ORS 568.900 to 568.933 and 561.191. If the department has reason to believe that agricultural 

discharges or activities are contributing to water quality problems resulting in water quality 

standards violations, the department may consult ODA. If water quality impacts are likely from 

agricultural sources and the department determines that a water quality management plan is 

necessary, the director may write a letter to the director of the ODA requesting that such a 

management plan be prepared and implemented to reduce pollutant loads and achieve the water 

quality criteria. In areas subject to the Agricultural Water Quality Management Act, the Oregon 

Department of Agriculture (ODA) under ORS 568.900 to 568.933 and 561.191 develops and 

implements agricultural water quality management area plans and rules to prevent and control 

water pollution from agricultural activities and soil erosion on agricultural and rural lands. 

Area plans and rules must be designed to achieve and maintain water quality standards. If the 

department determines that the area plan and rules are not adequate to achieve and maintain 

water quality standards, the department will provide ODA with comments on what would be 

sufficient to meet WQS or TMDL load allocations. If a resolution cannot be agreed upon, the 

department will request the Environmental Quality Commission (EQC) to petition ODA for a 

review of part or all of water quality management area plan and rules. If a person subject to an 

ODA area plan and implementing rules causes or contributes to water quality standards 

violations, the department will refer the activity to ODA for further evaluation and potential 

requirements.

Acknowledgement of OAR 340-041-0061(10) and (11) 

EPA acknowledges the revised language in OAR 340-041-0061(10) and (11) Other 

Implementation of Water Quality Criteria. The revised rules in (10) and (11) explain how state 

rules for forestry and agricultural nonpoint sources are to be implemented consistent with water 

quality standards and the total maximum daily load (TMDL) load allocations.187 These 

provisions set forth the extent to which Oregon requires nonpoint sources of pollution from 

forest operations under the Forest Practices Act and agricultural activities under the Agricultural 

Water Quality Management Act to control their discharges in order to protect water quality.

These rules state that forest operations and agricultural activities generally will not be deemed to 

cause violations of water quality standards if best management practices and control measures 

under the Forest Practices Act and water quality management area plans under the Agricultural 

Water Quality Management Act are followed and identify the process to be used when water 

quality concerns arise. Thus, the rule clarifies mechanisms for WQS implementation and 

 

187 ODEQ. June 7, 2011. Executive Summary. Human Health Toxics Rulemaking. Oregon Department of 

Environmental Quality. page 9. Available at: 

http://www.deq.state.or.us/wq/standards/docs/toxics/humanhealth/rulemaking/ExecSummary.pdf
Technical Support Document for EPA’s Action on Oregon’s New and Revised Human Health Water Quality Criteria

for Toxics and Associated Implementation Provisions Submitted July 12 and 21, 2011

October 17, 2011 

103

compliance. 

Whether a State chooses to make water quality standards directly enforceable for nonpoint 

sources is solely a matter of state law. The CWA requires NPDES permits for discharges from 

point sources and compliance with that permit, but does not require that states develop 

enforceable regulatory programs for nonpoint sources. These provisions are applicable only to 

nonpoint sources and how they comply with water quality standards and TMDL load allocations 

and as such are not water quality standards under section 303(c) of the CWA. Water quality 

standards are provisions of State or Federal law which consist of a designated use or uses for 

waters of the United States, and water quality criteria necessary to protect the uses (40 CFR 

131.3(i)). 

 

In addition, these provisions do not include language that has the effect of changing the level of 

protection provided by Oregon’s water quality criteria and therefore do not constitute new or 

revised water quality standards. The provisions define the extent to which forest operations and 

agricultural operations that result in nonpoint source discharges must control their discharges in 

order to comply with Oregon’s water quality standards, but they do not establish or revise any of 

the components of the water quality standards themselves. 

Therefore, these provisions are not considered water quality standards subject to EPA review and 

approval and EPA is taking no action to approve or disapprove the provisions. 

Acknowledgment of Section Renumbering in OAR 340-041-0061(2)-(16)

The revised rule contains revised paragraph numbers for subsections OAR 340-041-0061(2) 

through (16) as the variance rule in section (2) was moved to OAR 340-041-0059. EPA 

acknowledges the renumbering for subsections that were previously approved by EPA under 

303(c) of the CWA as a non-substantive formatting change which does not require EPA action.