Methodology for 

Oregon’s 2010 Water Quality Report

And List of Water Quality Limited 

Waters

(Pursuant to Clean Water Act Sections 303(d) and 

305(b) and OAR 340-041-0046)

DEQ Water Quality Division

Last Updated: 5/12/2011

By: Karla Urbanowicz

DEQ
This report prepared by:

Oregon Department of Environmental Quality

811 SW 6th Avenue

Portland, OR 97204

1-800-452-4011

www.oregon.gov/deq

Contact:

Karla Urbanowicz

(503) 229-6099
- iTable of Contents

Introduction ..................................................................................... 1

Oregon’s Water Quality Standards ................................................ 2

Information on Statewide Water Quality and Beneficial Use 

Support – Probabilistic Assessments ........................................... 5

Data Evaluation ............................................................................... 5

Call for Data.................................................................................. 5

Available Data............................................................................... 6

Metadata Requirements............................................................... 6

QA/QC Requirements................................................................... 7

2010 Integrated Report Assessment Categories .......................... 7

General Policy Discussion ........................................................... 10

De-Listing Water Bodies............................................................ 10

Segmentation ............................................................................. 11

Segment Identifiers .......................................................................... 11

Determining Segments and Segment Status................................. 12

General Segmentation Rules........................................................... 12

Segments for Temperature and Dissolved Oxygen ...................... 13

Tribal Waters .............................................................................. 14

Process.......................................................................................... 14

Oregon’s Assessment Protocols ................................................. 16

Division 41 Water Quality Standards: Beneficial Uses, Policies, 

and Criteria for Oregon................................................................. 16

Policy .......................................................................................... 16

Narrative Criteria ........................................................................ 16

Pollutants and Criteria ............................................................... 18

POLLUTANT: Aquatic Weeds or Algae ...........................................18

POLLUTANT: Bacteria - E. coli (Escherichia coli)..........................20

POLLUTANT: Bacteria - Enterococci ..............................................23

POLLUTANT: Bacteria – Fecal Coliform .........................................25
- iiPOLLUTANT: Biocriteria ..................................................................28

POLLUTANT: Chlorophyll a .............................................................33

POLLUTANT: pH ...............................................................................42

POLLUTANT: Sedimentation ...........................................................45

POLLUTANT: Temperature ..............................................................46

POLLUTANT: Total Dissolved Gas..................................................49

POLLUTANT: Toxic Substances......................................................50

POLLUTANT: Turbidity.....................................................................63

Appendix 1: Rules for Defining Water Body Segments and Assigning 

Assessment Status Category

Appendix 2: Letter DEQ to EPA 6/22/1998 Re: Policy clarification of the 

Oregon water quality standards revisions

Appendix 3: Letter DEQ to EPA, 2/4/2004 Re: Oregon Responses to EPA 

Questions re the State’s water quality temperature standards
May 12, 2011 Page 1

Introduction

The federal Clean Water Act (CWA) Section 305(b) requires States submit a biennial 

water quality inventory report in April of even numbered years. The report provides 

information on the water quality of all navigable state waters; the extent to which state 

waters provide for the protection and propagation of a balanced population of shellfish, 

fish, and wildlife, and allow recreational activities in and on the water; and how pollution 

control measures are leading to water quality standards being met.

The CWA Section 303(d) additionally requires each State identify state waters where

existing pollution controls are not stringent enough to achieve state water quality 

standards, and establish a priority ranking of these waters. Section 303(d) requires States

to develop Total Maximum Daily Loads (TMDLs) for the identified waters. TMDLs 

describe the amount of each pollutant a water body can receive and not violate water 

quality standards. States submit the list of waters needing TMDLs (303(d) list) to EPA 

and EPA either approves or disapproves the list within thirty days after the submission.

EPA regulations (40 CFR 130.7 and 40 CFR 130.8) specify the process for developing 

the 303(d) list and the content of the biennial water quality report. EPA guidance

recommends that States submit an integrated report to satisfy 305(b) and 303(d)

requirements.1The integrated report presents the results of assessing available data to 

determine where water quality standards are met or not met, and identifies the pollutants 

causing water quality limitations or impairments.

EPA regulations require States to describe the methodology, data, and information used 

to identify and list water quality limited segments requiring TMDLs. The assessment 

methodology contains the "decision rules" used to evaluate data and information. Oregon 

Administrative Rules (OAR 340-041-0046) also require the specific evaluation process 

be identified.

This document, Methodology for Oregon’s 2010 Water Quality Report and List of 

Water Quality Limited Waters, describes how DEQ developed Oregon’s 2010 

Integrated Report for 305(b) and 303(d). The methodology is consistent with key 

elements of Oregon’s water quality standards including designated uses, narrative and 

numeric criteria, antidegradation requirements, and implementation procedures 

associated with the standards and is the framework DEQ uses to assess water quality 

conditions.

 

1 October 12, 2006, Memorandum from Diane Regas, EPA Office of Wetlands, 

Oceans and Watershed Re: Information Concerning 2008 Clean Water Act Sections 

303(d), 305(b), and 314 Integrated Reporting and Listing Decisions 

http://www.epa.gov/owow/tmdl/2008_ir_memorandum.html
May 12, 2011 Page 2

The assessment methodology is consistent with the following:

 Water Quality Standards, Beneficial Uses, Policies, and Criteria for Oregon: 

Oregon Administrative Rules Chapter 340 Division 41. 

http://arcweb.sos.state.or.us/rules/OARs_300/OAR_340/340_041.html

 Letter from DEQ to EPA, Region 10, Policy clarifications for Oregon’s water 

quality standards interpretation, June 22, 1998.

 Letter from DEQ to EPA Region 10, Oregon responses to EPA questions re: the 

State’s water quality temperature standards, February 4, 2004.

 May 5, 2009, Memorandum from Suzanne Schwartz, EPA Office of Wetlands, 

Oceans, and Watersheds Re: Information Concerning 2010 Clean Water Act 

Sections 303(d), 305(b), and 314 Integrated Reporting and Listing Decisions

http://water.epa.gov/lawsregs/lawsguidance/cwa/tmdl/final52009.cfm

 October 12, 2006, Memorandum from Diane Regas, EPA Office of Wetlands, 

Oceans and Watershed Re: Information Concerning 2008 Clean Water Act 

Sections 303(d), 305(b), and 314 Integrated Reporting and Listing Decisions 

http://www.epa.gov/owow/tmdl/2008_ir_memorandum.html

 Guidance for 2006 Assessment, Listing and Reporting Requirements Pursuant to 

Sections 303(d), 305(b), and 314 of the Clean Water Act: United States 

Environmental Protection Agency, (July 29, 2005)

http://www.epa.gov/owow/tmdl/2006IRG/

 Guidance for 2004 Assessment, Listing and Reporting Requirements Pursuant to 

Sections 303(d) and 305(b) of the Clean Water Act: United States Environmental 

Protection Agency, (July 21, 2003)

http://www.epa.gov/owow/tmdl/tmdl0103/index.html

 Federal Water Pollution Control Act Chapter 26 Water Pollution Prevention and 

Control 

 40 CFR Part 130.7 (Code of Federal Regulations)

 40 CFR Part 130.8 (Code of Federal Regulations)

Oregon’s Water Quality Standards

The objective of the Clean Water Act is to restore and maintain the physical, chemical 

and biological integrity of the Nation’s waters (CWA Section 101(a)). To achieve this

objective, States develop and adopt water quality standards. Water quality standards 

include beneficial uses, narrative and numeric criteria, and antidegradation policies.

Oregon’s water quality standards are adopted in Oregon Administrative Rules (OAR)

Chapter 340 Division 41 (http://www.deq.state.or.us/regulations/rules.htm ). These rules 

include policies and criteria that are applicable throughout the state.

Beneficial uses are designated by the State of Oregon Water Resources Department and 

the Oregon Environmental Quality Commission. Basin-specific beneficial uses and fish 

uses are designated in OAR 340-041-0101 through OAR 340-041-0340. Fish use 

designations include explicit water body segment locations and time periods for fish uses 

and life stages. For example, the beneficial uses protected in the Main Stem Columbia 
May 12, 2011 Page 3

River are designated in OAR 340-041-0101(1) and (2) and shown in Table 101A and 

Table 101B as follows:

340-041-0101

Beneficial Uses to Be Protected in the Main Stem Columbia River

(1) Water quality in the main stem Columbia River (see Figure 1) must be 

managed to protect the designated beneficial uses shown in Table 101A 

(November 2003).

(2) Designated fish uses to be protected in the main stem Columbia River are 

shown in Table 101B (November 2003).

Table 101A

Designated Beneficial Uses

Mainstem Columbia River

Beneficial Uses Columbia River

Mouth to RM 86

Columbia River

RM 86 to 309

Public Domestic Water 

Supply1

X X

Private Domestic Water 

Supply1

X X

Industrial Water Supply X X

Irrigation X X

Livestock Watering X X

Fish & Aquatic Life2 X X

Wildlife & Hunting X X

Fishing X X

Boating X X

Water Contact Recreation X X

Aesthetic Quality X X

Hydro Power X

Commercial Navigation & 

Transportation

X X

1 With adequate pretreatment and natural quality that meets drinking water standards.

2 See also Table 101B for fish use designations for this river.

Table produced November, 2003

http://www.deq.state.or.us/wq/rules/div041/dbutables/table101a.pdf
May 12, 2011 Page 4

Table 101B

Beneficial Use Designations – Fish Uses

Mainstem Columbia River

Geographic Extent of Use Salmon and 

Steelhead 

Migration 

Corridors

(20°C)

Salmon and 

Steelhead 

Spawning 

through Fry 

Emergence

Shad and 

Sturgeon 

Spawning 

and 

Rearing

Mainstem Columbia River

Beacon Rock to Upstream of Ives Island 

(RM 141.5 to RM 143.5)

October 15 -

March 31

Columbia River, mouth to WA border 

(RM309)

X

Columbia River (RM 147 to RM 203) X

Table produced November, 2003

http://www.deq.state.or.us/wq/rules/div041/futables/table101b.pdf

Oregon water quality standards include statewide narrative criteria established in OAR 

340-041-0007. Narrative criteria include provisions for:

o Less stringent natural conditions to supersede numeric criteria (OAR 340-041-

0007(2),

o Prohibitions on fungi or other growths that negatively impact beneficial uses 

(OAR 340-041-0007(11),

o Prohibitions on tastes, odors, or toxic conditions that negatively impact beneficial 

uses (OAR 340-041-0007(12), and

o Prohibitions on bottom deposits that negatively impact beneficial uses (OAR 340-

041-0007(13).

DEQ applies statewide narrative criteria 340-041-0007(2) that allow for less stringent 

natural conditions to supersede numeric criteria using guidance provided by EPA Region 

10 and DEQ agreements with EPA.

2, 3 Oregon water quality standards for specific 

pollutants are established in OAR 340-041-0009 (Bacteria) through OAR 340-041-0036

(Turbidity). For this assessment, each pollutant is assessed independently. The 

methodology for each pollutant is discussed in later sections of this document. Oregon’s 

standards for Toxic Substances (OAR 340-041-0033) were revised in 2004, but have not 

 

2

EPA Region 10, April, 2005, Principles to Consider When Reviewing and Using 

Natural Condition Provisions 

http://yosemite.epa.gov/r10/water.NSF/840a5de5d0a8d1418825650f00715a27/35a31c9a

efba540188256fd60076c840?OpenDocument#The%20Document

3 DEQ, February 4, 2004, Clarification Letter from DEQ to EPA,

http://www.deq.state.or.us/wq/standards/docs/temperature/clarificationltr.pdf
May 12, 2011 Page 5

yet been approved by EPA. Numeric criteria in Table 20 for toxic substances remain the 

effective criteria for CWA 305(b) and 303(d) assessment purposes. Temperature criteria 

(OAR 340-041-0028) for temperature-sensitive fish uses, including specific salmonid life 

cycle stages, were adopted by Oregon in 2003 and approved by EPA and are applicable 

for assessment purposes at the locations and time periods when those fish uses are 

designated. Dissolved oxygen criteria for specific fish use and life cycle stages are also 

applicable where those uses are designated.

A statewide antidegradation policy is established in OAR 340-041-0004 to guide 

decisions that affect water quality. Additional policies for applying water quality 

standards to determine water quality limited waters, in mixing zones, at wastewater 

treatment works, and other implementation policies are contained in OAR 340-041-0046 

to OAR 340-041-0061.

Information on Statewide Water Quality and Beneficial 

Use Support – Probabilistic Assessments

DEQ has participated in the national Western States Environmental Monitoring and 

Assessment Program (W-EMAP). The studies use a probabilistic sampling design to poll 

a statistically determined number of sites to represent water quality, physical habitat, and 

ecological conditions on statewide or basin-level scales. This differs from targeted 

sampling that represents a single site or small water segment. The probabilistic studies

collect chemical, physical, and biological data from a set of randomly selected sites on 

perennial and wadeable streams in Oregon. The conclusions from the probabilistic studies

provide generalized information about water quality and beneficial use support for 

Oregon as a whole. Information about physical habitat conditions does not specifically 

indicate beneficial uses are impaired or that a pollutant is present. Probabilistic 

assessment information is often presented in terms of disturbance or differences between 

sample sites and reference conditions for undisturbed sites.

Results from probabilistic assessments are not used to evaluate individual water bodies or 

assessment units. However, data from individual monitoring sites are used to evaluate 

individual water bodies or assessment units.

Data Evaluation

To gather information on water quality throughout Oregon, DEQ reviewed water quality 

data available from agency monitoring activities, solicited data from outside the agency, 

and reviewed other available data and information.

Call for Data

A public call for data for the 2010 Integrated Report evaluation was issued and data 

submittals to DEQ were accepted from May 11 through June 11, 2009. The call for data 

included a description of the requirements for data type, quality assurance/quality control 

(QA/QC), and data formats. Information for the call for data was available on-line at 
May 12, 2011 Page 6

http://www.deq.state.or.us/wq/assessment/2010Report.htm . Data collected since the last 

call for data (May 2003) was solicited. Data submitted to DEQ were reviewed for data 

quality level, then uploaded and stored in DEQ’s Laboratory Analytical and Storage 

Retrieval (LASAR) database.

Available Data

For the 2010 Integrated Report data evaluation, available data were retrieved from DEQ’s 

Laboratory Analytical and Storage Retrieval (LASAR) database for the time period June 

1, 1999 through May 31, 2009. Only high quality data graded as data quality level A or B 

were evaluated for the 305(b)/303(d) assessment. The data evaluation focused on grab 

sample results available in LASAR that were retrieved on November 20, 2009. Data from

continuous sampling data loggers, which are primarily data for stream temperature, were 

not retrieved for the 2010 evaluation.

Metadata Requirements

For monitoring data submittals, DEQ requires sampling site descriptions and geographic 

information for each sampling location. This location information must include 

monitoring station latitude, longitude, LLID, and river mile, as described below.

DEQ uses a 1:100,000 geo-referenced river reach system compiled for the Pacific 

Northwest. The river reach system is the hydrography component in a regional rivers and 

fisheries information system known as StreamNet. Information about this system is 

available at http://www.streamnet.org/pnwr/PNWNAR.html . A stream based identifier 

called the LLID (Longitude/Latitude ID) is used to uniquely identify streams and lakes.

This attribute consists of the longitude and latitude of the mouth of the stream or the 

center of a lake. All reaches that comprise a given stream are assigned this unique LLID.

Longitude precedes latitude to conform to standard x, y ordering. The code is 13 

characters long, with 7 for decimal degrees of longitude and 6 for decimal degrees of 

latitude, with implied decimal points.

The LLID consists of the Longitude/Latitude at the mouth of the stream or the centroid of 

a lake/reservoir/pond polygon. Only one LLID exists for a stream. River mile 0 is 

assigned at the mouth of the stream at the intersection with the next order stream. Lakes 

and reservoirs can be identified by both a lake LLID, assigned as river mile 0 at the

center point, and a stream LLID with the river mile maximum at the inlet and minimum 

at the outlet to the water body. Some water bodies do not have an assigned LLID and 

cannot be located on the StreamNet 1:100,000 river reach system. In those cases, other

georeferenced base layers such as the Pacific Northwest Hydrography 1:24,000 layer or 

National Hydrography Data were used to reference a GIS feature. In a few cases where 

the feature was apparent on satellite imagery, but not identified on available GIS base

layers, DEQ digitized the feature and assigned an LLID using the protocols described 

above. In earlier assessment cycles, water bodies that did not have a georeferenced LLID

were given a placeholder LLID (such as 1111111111111) so that information could be

retained in the assessment database even though not available for GIS applications.

Where possible, these stream were identified using the most current GIS information 

available in 2010 and corrected in the database.
May 12, 2011 Page 7

QA/QC Requirements

Data must be high quality and meet data quality level A or B requirements to be 

evaluated for the 305(b)/303(d) assessment. Analytical laboratory data are assessed 

against current Quality Control (QC) limits established by the referenced analytical 

method and/or the QC limits established by the laboratory that performed the testing and 

supplied to DEQ. DEQ also utilizes EPA National Functional Guidelines for Data 

Review as guidance when assessing laboratory data. 

http://www.epa.gov/superfund/programs/clp/guidance.htm

DEQs Data Quality Matrix (March 2009) provides data validation criteria for water 

quality parameters measured in the field.

http://www.deq.state.or.us/lab/techrpts/docs/DEQ04-LAB-0003-QAG.pdf

2010 Integrated Report Assessment Categories

Assigning a water quality assessment category to Oregon’s waters is a significant feature 

of Oregon’s 2010 Integrated Report. EPA continues to recommend using five categories 

to classify water quality status.4The categories represent varying levels of water quality 

standards attainment and beneficial use support, ranging from Category 1, where all

designated uses for a water body are supported, to Category 5, where a pollutant impairs 

a water body and a TMDL is required to return the water to a condition where the water 

quality standards are met. The category assignments are based on evaluating all existing 

and readily available data and information consistent with Oregon’s standards and 

assessment methodology. In general terms, the assessment categories are:

Category 1: All designated uses are supported. (Oregon does not use this 

category.)

Category 2: Available data and information indicate that some designated 

uses are supported and the water quality standard is attained.

Category 3: Insufficient data to determine whether a designated use is 

supported. Oregon further sub-classifies waters if warranted as:

3B: Insufficient data to determine use support but some data 

indicate non-attainment of a criterion and a potential concern.

3C: Impairing pollutant unknown.

Category 4: Data indicate that at least one designated use is not support but a 

TMDL is not needed. This includes:

4A: TMDLs that will result in attainment of water quality 

standards have been approved.

4B: Other pollution control requirements are expected to 

address pollutants and will result in attainment of water quality 

standards.

 

4 Guidance for 2006 Assessment, Listing and Reporting Requirements Pursuant to Sections 303(d) and 

305(b) of the Clean Water Act: United States Environmental Protection Agency, (July 29, 2005)

http://www.epa.gov/owow/tmdl/2006IRG/
May 12, 2011 Page 8

4C: Impairment is not caused by a pollutant (e.g., flow or lack 

of flow are not considered pollutants).

Category 5: Data indicate a designated use is not supported or a water quality 

standard is not attained and a TMDL is needed. This category 

constitutes the Section 303(d) list that EPA will approve or 

disapprove under the Clean Water Act.

Oregon uses the policy of independent applicability to assess attainment of water quality 

standards, as recommended by EPA.5Each water quality standard is evaluated 

independently and a category assigned for each standard where data are available. Since 

no water body has sufficient data or information on all designated uses and water quality 

standards, no waters are assigned to Category 1.

The following flow chart (Figure 3) summarizes Oregon’s assessment process.

 

5 Guidance for 2006 Assessment, Listing and Reporting Requirements Pursuant to Sections 303(d) and 

305(b) of the Clean Water Act: United States Environmental Protection Agency, (July 29, 2005)

http://www.epa.gov/owow/tmdl/2006IRG/
May 12, 2011 Page 9

Figure 3: Water Quality Report Assessment Categories

No

Yes

No

No

Yes

No

No

No assessment status assigned.

Category 3: Insufficient Data are 

available to determine if criterion or use 

is attained or not attained for the water 

body.

Do available data indicate 

non-attainment of criteria?

Water body may be placed 

in Category 3B: Potential 

Concern.

Category 2: Water body Attaining

some criteria or designated uses.

Category 4A: Water body is Water Quality Limited but 

a TMDL is not required because the TMDL has been 

approved.

Category 5: Water body is Water Quality Limited and 

requires a TMDL. Water body is placed on the 303(d) 

List.

Category 4C: Water body is Water Quality Limited but 

a pollutant does not cause the impairment. A TMDL is 

not required.

Yes

Yes

Yes

Yes

No

Yes

No

Are any data available to 

support an attainment 

decision for at least one 

criterion or use?

Do data meet minimum 

sample requirements for 

evaluation?

Do data demonstrate 

attainment of applicable 

criteria or uses?

Do data meet the meta-data 

and QA/QC requirements 

for evaluation?

Does a pollutant cause nonattainment?

Has a TMDL been 

completed and approved for 

the pollutant causing the 

impairment?

Are other control measures 

in place?

Category 4B: Water body is Water Quality Limited but 

a TMDL is not required because other pollution 

requirements will achieve water quality standards.

No

Yes

Water body may be placed in Category 3C: Impairing 

Pollutant Unknown Unknown
May 12, 2011 Page 10

The data and sample requirements for each pollutant are discussed in the section below 

titled: Oregon’s Assessment Protocols by Pollutant. Data at individual sampling sites 

are evaluated independently according to these requirements to determine if sufficient 

information is available and, if so, assign a status to the monitoring site. Results for the 

monitoring sites are then grouped to determine the status for an assessment unit or 

segment of the water body. Rules for defining water body segments are discussing in the 

General Policy Discussion section on Segmentation. 

General Policy Discussion

De-Listing Water Bodies

Water bodies placed on a 303(d) list in a previous assessment year remain on the 2010

Category 5: 303(d) list unless they are de-listed. Water bodies may be de-listed if:

1. New information is available that shows water quality standards are being met. A 

water body may de-listed and assigned to Category 2: Attaining if new information 

shows water quality standards are being met. Data for de-listing consideration must 

be Data Quality Level A or B and meet the minimum sample requirements.

Generally, similar data are required to de-list a water body as initially used to place 

the water body on the 303(d) list. For example, if the listing was based on two 

successive years of a standard not being met, DEQ would look for at least two 

successive years of data indicating that the standard is being met.

2. Additional data are submitted to correct a flaw in the original assessment. For 

example, a water body may have been placed on a previous 303(d) list but some data 

may not have been evaluated if QA/QC requirements were not met. If more recently 

collected data meet the QA/QC requirements and indicate compliance with the 

applicable criterion, the water body will be de-listed.

3. Water quality criteria are changed or no longer apply in certain water bodies. For 

example, Oregon’s water quality standards were revised and fish beneficial use

designations were clarified in December 2003. Numeric criteria for temperature were 

changed. The assessment applies criteria for temperature and dissolved oxygen using 

the fish beneficial uses designated in 2003. If data are available on a previously listed 

water body and an evaluation shows that the current applicable standards are met, the 

water body is de-listed. The previously listed record, with the original listing criterion

and beneficial use, notes Criteria change or use clarification under “Status” and the 

“Action” notes Delisted - Revised criteria or uses met. If no data are available to 

evaluate against current applicable criteria, the water body remains on the 303(d) list.

However, when water bodies were listed in a previous assessment for salmonid

spawning, but the new fish use designation does not include salmon or steelhead 

spawning use, the water body is de-listed for spawning, noting Criteria change or 

use clarification under “Status” and Delisted - Criteria change or use clarification

under “Action”. The water body is assigned to a category using available data and the 

current designated uses and applicable criteria. A water body may be de-listed for 
May 12, 2011 Page 11

spawning, but may be listed for exceeding year round, non-spawning criteria for 

temperature or dissolved oxygen or for another salmon and steelhead spawning use.

4. The water body and pollutant are addressed in a TMDL approved by EPA. Water 

body segments with an approved TMDL will be removed from the 303(d) list, but 

will retain their water quality limited status (per OAR 340-41-006(30)) until they 

meet water quality standards. The water body will be de-listed and be placed in 

Category 4A: Water Quality Limited TMDL Approved. If a TMDL is developed 

for a pollutant on a watershed scale, all water bodies within the watershed will be delisted and placed in Category 4A.

5. When a pollutant does not cause the water body impairment, the water will be placed 

in Category 4C: Water Quality Limited but a pollutant does not cause the

impairment. EPA defines a pollutant according to Section 502(6) of the Clean Water 

Act. In Oregon’s 1998 assessment, DEQ placed water bodies on the 303(d) list for

habitat modification and flow modification. Habitat modification listings were based 

on information indicating inadequate pool frequency and lack of large woody debris.

Flow modification listings were based on inadequate flow to maintain in-stream water 

rights purchased by Oregon Department of Fish and Wildlife. However, EPA 

subsequently clarified that flow and habitat modification are not considered pollutants 

under the Clean Water Act. In 2002, ODEQ removed these water bodies from the 

303(d) list. Another example is water bodies listed in 1998 for not meeting narrative 

biocriteria. Biocriteria are not based on measures of a pollutant, but pollutants such as 

temperature and dissolved oxygen may cause conditions that lead to detrimental 

changes in the biological community. TMDLs can be established for the pollutants 

that will also improve the biological conditions. The water will be de-listed for 

biocriteria based on the documentation showing that the pollutant TMDL will also 

address biological conditions. If data indicate that a pollutant is not the cause of the 

biological impairment, the water will be de-listed and placed in Category 4C.

6. Other pollution control requirements are in place and water quality standards will be 

achieved in a reasonable period of time. Examples include point source permits or 

CWA Section 401 certification conditions for hydroelectric projects that address all

pollutant sources on a water body. The measures and conditions will results in water 

quality improvements. When these control measures are in place, the water bodies 

will be de-listed and placed in Category 4B: Water Quality Limited Other Control 

Measures in Place.

Segmentation

Segment Identifiers

Segments for assessment and listing purposes are identified using a geo-referenced water 

body identifier and the starting and ending river miles for the assessment unit.

DEQ uses the 1:100,000 geo-referenced river reach system compiled for the Pacific 

Northwest. The river reach system is the hydrography component in a regional rivers and 
May 12, 2011 Page 12

fisheries information system known as StreamNet. Information about this system is 

available at http://www.streamnet.org/pnwr/PNWNAR.html. An identifier called the 

LLID (Longitude/Latitude ID) is used to uniquely identify the water body. This attribute 

consists of the longitude and latitude at the mouth of a stream or center of a lake. All 

reaches that comprise a given stream are assigned this unique LLID. Longitude precedes 

latitude to conform to standard x, y ordering. The code is 13 characters long, with 7 for 

decimal degrees of longitude and 6 for decimal degrees of latitude, with implied decimal 

points. Only one LLID is used for a stream. Lakes and reservoirs may sometimes be 

identified by both a stream LLID, with the river miles at the inlet and outlet of the lake or 

reservoir, and a lake LLID, with river miles assigned as “0”.

Some water bodies evaluated for the 2010 Integrated Report do not have an LLID 

assigned in the StreamNet 1:100,000 river reach system. Where water bodies do not have 

an LLID, a placeholder LLID was created so that information on this water body is

retained in the assessment database. These water bodies do not have river miles assigned 

to the segments.

Determining Segments and Segment Status

Oregon revised water quality standards in 2003 for temperature and clarified fish use 

designations in water bodies throughout the state. For the 2010 Water Quality Report, 

assessment unit segments are defined by these fish use designations for criteria that 

protect these uses. Oregon has specific temperature and dissolved oxygen numeric 

criteria protecting various fish uses and life stages including criteria to protect salmon 

and steelhead and resident trout spawning at designated locations and time periods. For 

assessing temperature and dissolved oxygen, the segment lengths are determined based 

on specific fish beneficial use designations. For other pollutants, segment lengths are 

determined following general protocols based on the spatial distribution of monitoring 

sites on a water body. The available data at a monitoring station are evaluated to 

determine if a standard is met at that station. The status for the segment is then 

determined based on the status of the monitoring stations in the segment. The following 

paragraphs and a summary table in Appendix 1 provide the decision rules used for the 

2010 Integrated Report to define assessment unit segments and assign a status category to 

the segment.

General Segmentation Rules

Assessment unit segments are determined by:

1. Segments already established in previous assessments;

2. For a water body with only one monitoring site, the assessment unit segment is from 

mouth to headwaters; or

3. For a water body with multiple monitoring sites, monitoring stations with sufficient 

information and the same status are grouped in a segment established at locations 

upstream and downstream of the monitoring stations.

The assessment status for the segment is determined based on evaluating data at each 

monitoring site in a segment. When any station in a segment does not meet water quality 

standards, the segment is assigned Category 5 status. If one or more stations in a segment 
May 12, 2011 Page 13

meet water quality standards, the segment is assigned Category 2 status. Monitoring 

stations without sufficient data to assign a status are not used to define segment lengths.

(See Appendix 1 tables).

Segments for Temperature and Dissolved Oxygen

The following steps are used to determine segments for assessing temperature and 

dissolved oxygen criteria attainment:

1. Segments are defined for sequential sections of a water body with the same 

designated fish use.

2. Segments for fish spawning use are defined for sequential sections of a water body 

with the same designated spawning time period. On one water body, the segments for 

spawning may be different than the segments for the non-spawning fish uses.

3. The spawning criteria apply during the designated spawning time, and the nonspawning criteria apply at all other times. Available data are evaluated for the 

applicable criteria and time period in segments defined for those uses. If data at any 

monitoring station in the segment does not meet numeric criteria for temperature or 

dissolved oxygen, the entire segment with that fish use is assigned Category 5 status.

If data at any point on the segment does not meet numeric criteria for temperature or 

dissolved oxygen during the designated spawning period, the entire segment 

designated for spawning in that time period is assigned Category 5 status for 

spawning use.

For example, the Sandy River (LLID 1224071455697) is designated for salmon and trout 

rearing and migration from river mile 0 to 26 (Segment “A”) and for core cold water 

habitat from river mile 26 to 55.5 (Segment “B”). The Sandy River also has four reaches

designated for spawning use during different time periods (Segments “C” through “F”) 

and one with no spawning, as shown in the following table. Data from four monitoring 

stations at river miles 6, 19, 30, and 38 were compared to the specific numeric 

temperature criteria for each fish use. Data were available during the spawning time 

period at stations located on river miles 30 and 38 within Segment “D”. Data exceeded 

the non-spawning temperature criteria in Segments “A” and “B”, and the spawning 

criteria during the spawning period for Segment “D”. These segments are assigned the 

Category 5 303(d) list. (Note: A TMDL was approved for the Sandy River on 4/15/2005

and the current assigned segment status is Category 4A.)

Table 3: Example Fish Beneficial Use Segments – Sandy River

Segment River 

Mile 

Start

River 

Mile 

End

Use Spawning 

Period

Numeric 

Criteria

(

o Celsius)

Status

A 0 26 Salmon and 

trout rearing 

and migration

18.0 Category 5 

303(d) list

B 26 55.5 Core cold 

water habitat

16.0 Category 5 

303(d) list

C 0 26 Spawning October 15 –

May 15

13.0

D 26 48 Spawning August 15 – 13.0 Category 5 
May 12, 2011 Page 14

June 15 303(d) list

E 48 49.1 Spawning October 15 –

June 15

13.0

F 49 54 Spawning January 1 –

June 15

13.0

54 55.4 No spawning

Tribal Waters

Only those waters that are under the State of Oregon’s jurisdiction are subject to the 

State’s 303(d) and 305(b) activities. Oregon’s 2010 Integrated Report does not 

intentionally include tribal waters.

When a water body lies partially within Tribal Reservation boundaries, DEQ will only 

include the portions that are within Oregon’s jurisdiction on Oregon’s 303(d) list. DEQ

will use a map provided by the Confederated Tribes of the Umatilla Indian Reservation 

(CTUIR) to determine which waters were within Umatilla tribal lands (data origin: BIA 

Geographic Data Service Center, publication date: 1999, title: Diminished Reservation 

Boundary for CTUIR).

Oregon does not develop TMDLs for tribal waters. When a 303(d) listed water body is 

fully on Tribal lands, the Tribe may work directly with EPA to develop the TMDL.

Process

The DEQ process to develop Oregon’s 2010 Integrated Report included the following 

steps and timelines:

1. Data Gathering and Review: DEQ solicited data from federal and other state 

agencies, tribes, local governments, watershed councils, private and public 

organizations and individuals. DEQ issued a public notice seeking data on the 

condition of Oregon’s surface waters and requesting data be submitted during a 

specified time period using specified formats for electronic data processing. DEQ

notified the public using an interested parties mailing list and electronic notice 

subscription list. Data submittals to DEQ were accepted from May 11 through June 

11, 2009. DEQ reviewed and uploaded data into DEQ’s LASAR data storage system. 

Data meeting QA/QC, metadata, and sampling requirements were retrieved from 

LASAR on November 20, 2009 for evaluation. DEQ prioritized the assessment of the 

data using a strategy and rationale outlined in the public call for data. Assessments 

were completed using a phased approach.

2. Public Review Process: A draft 2010 Integrated Report and a draft 2010 list of water 

quality limited waters were available for public review and comment from November 

15, 2010 through 5:00 PM PST December 15, 2010. The draft list included updates 

based on review of data for a set of pollutants and beneficial use impairments that 

were complete and ready for public review. A public hearing to take comment on the 
May 12, 2011 Page 15

draft list was held on November 30, 2010. No comments were received at the public 

hearing.

3. 2010 Integrated Report and 303(d) List: DEQ reviewed public comments and, where 

appropriate, revised the water quality report and Section 303(d) list of Category 5: 

Water quality limited waters needing a TMDL. DEQ submitted Oregon’s 2010

Section 303(d) list of Category 5: Water quality limited waters needing a TMDL to 

US EPA Region 10 on January 31, 2011. Along with the Section 303(d) list, DEQ

also submitted the 2010 Integrated Report, response to comments, the Assessment 

Methodology for Oregon's 2010 Integrated Report on Water Quality Status, and a 

prioritization and TMDL schedule to EPA. Only water bodies in the Category 5: 

Water quality limited waters needing a TMDL (Section 303(d) list) are subject to 

EPA’s approval.

4. Final Supplement to Oregon’s 2010 Integrated Report and 303(d) List: DEQ 

completed a second and final phase of data and information review and prepared a 

supplement to the 2010 Integrated Report and 303(d) List. DEQ provided an 

opportunity for public review and comment on the final supplement from April 12, 

2011 through 5:00 PM PDT May 3, 2011. A hearing to take public comment was held 

on April 18, 2011 in Portland, Oregon. After reviewing comments, DEQ finalized the 

2010 Integrated Report and made changes to the Methodology for Oregon's 2010 

Integrated Report and List of Water Quality Limited Waters and the TMDL 

prioritization and schedule. DEQ will submit the 2010 Integrated Report and 303(d) 

List, along with the response to comments on the supplement, the Methodology for 

Oregon's 2010 Integrated Report on Water Quality Status, and the prioritization and 

TMDL schedule to EPA for review and approval.
May 12, 2011 Page 16

Oregon’s Assessment Protocols

For the 2010 Integrated Report, DEQ will evaluate water quality data to determine if 

water quality standards set out in Oregon Administrative Rules Chapter 340 Division 41 

are being met in Oregon. In the following sections, the assessment protocols used to 

determine the water quality status and assign an assessment category to a water body are 

discussed for specific pollutants, narrative and numeric criteria, and designated uses. The 

narrative and numeric criteria from Oregon Administrative Rules and federal criteria,

where applicable, are cited for each pollutant. Each pollutant and criterion is evaluated 

independently. Data are evaluated for each monitoring site, and an overall status assigned 

to the water body assessment unit segment based on the available monitoring data. Data 

are not available for all pollutants in each water body. Therefore, Category 1 indicating 

all designated uses are supported and all criteria are met is not used for Oregon’s 

assessment.

Division 41 Water Quality Standards: Beneficial Uses, 

Policies, and Criteria for Oregon

Policy

340-041-0004

Antidegradation

(1) Purpose. The purpose of the Antidegradation Policy is to guide decisions that 

affect water quality such that unnecessary further degradation from new or 

increased point and nonpoint sources of pollution is prevented, and to protect, 

maintain, and enhance existing surface water quality to ensure the full protection 

of all existing beneficial uses. The standards and policies set forth in OAR 340-

041-0007 through 340-041-0350 are intended to supplement the Antidegradation 

Policy.

Narrative Criteria

340-041-0007

Statewide Narrative Criteria

(1) Notwithstanding the water quality standards contained in this Division, the 

highest and best practicable treatment and/or control of wastes, activities, and 

flows must in every case be provided so as to maintain dissolved oxygen and 

overall water quality at the highest possible levels and water temperatures, 

coliform bacteria concentrations, dissolved chemical substances, toxic materials, 

radioactivity, turbidities, color, odor, and other deleterious factors at the lowest 

possible levels.
May 12, 2011 Page 17

(2) Where a less stringent natural condition of a water of the State exceeds the 

numeric criteria set out in this Division, the natural condition supersedes the 

numeric criteria and becomes the standard for that water body. However, there are 

special restrictions, described in OAR 340-041-0004(9)(a)(D)(iii), that may apply 

to discharges that affect dissolved oxygen.

(4) No discharges of wastes to lakes or reservoirs may be allowed except as 

provided in section OAR 340-041-0004(9).

[...]

(10) The development of fungi or other growths having a deleterious effect on 

stream bottoms, fish or other aquatic life, or that are injurious to health, 

recreation, or industry may not be allowed;

(11) The creation of tastes or odors or toxic or other conditions that are 

deleterious to fish or other aquatic life or affect the potability of drinking water or 

the palatability of fish or shellfish may not be allowed;

(12) The formation of appreciable bottom or sludge deposits or the formation of 

any organic or inorganic deposits deleterious to fish or other aquatic life or 

injurious to public health, recreation, or industry may not be allowed;

(13) Objectionable discoloration, scum, oily sheens, or floating solids, or coating 

of aquatic life with oil films may not be allowed;

(14) Aesthetic conditions offensive to the human senses of sight, taste, smell, or 

touch may not be allowed;

(15) Radioisotope concentrations may not exceed maximum permissible 

concentrations (MPC's) in drinking water, edible fishes or shellfishes, wildlife, 

irrigated crops, livestock and dairy products, or pose an external radiation hazard;

[...]
May 12, 2011 Page 18

Pollutants and Criteria

POLLUTANT: Aquatic Weeds or Algae

BENEFICIAL USES AFFECTED: Domestic and Industrial Water Supply, 

Irrigation, Livestock Watering, Fish and 

Aquatic Life, Fishing, Boating, Water 

Contact Recreation, Aesthetic Quality

NARRATIVE CRITERION: OAR 340-041-007(10)

340-041-0007

Statewide Narrative Criteria

(10) The development of fungi or other growths having a deleterious effect on 

stream bottoms, fish or other aquatic life, or that are injurious to health, 

recreation, or industry may not be allowed;

NUMERIC CRITERION: See Chlorophyll a under 

Nuisance Phytoplankton Growth

(OAR 340-041-0019)

NARRATIVE ASSESSMENT PROTOCOL:

This protocol will be used to implement the statewide narrative criterion that prohibits 

deleterious or injurious effects on aquatic and human beneficial uses from biological 

growths, and will be applied specifically to aquatic weeds or algae. The growth of aquatic 

weeds or algae does not in itself indicate deleterious or injurious effects on beneficial 

uses, or identify which pollutant should be addressed by point source or other controls 

through a Total Maximum Daily Load. This assessment protocol identifies the indicators 

that will be used to determine that beneficial uses have been negatively affected.

ASSIGNMENT OF ASSESSMENT CATEGORY:

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

 Aquatic Weeds: Documented reports of excessive growths of invasive, non-native 

aquatic plants that dominate the assemblage in a water body and have a harmful 

effect on fish or aquatic life or are injurious to health, recreation, or industry.

Plants include aquatic species on the Oregon Department of Agriculture Noxious 

Weed Policy and Classification System designated as “A”, “B”, or “T” weeds or 

those covered by a quarantine in OAR 603-052-1200.

 Algae: Health advisories issued by the Oregon Department of Human Services, in 

conjunction with other federal, state, county, city or local agencies warning that 

potentially harmful levels of toxins produced by blue-green algae (cyanobacteria)

are present in a water body. Health advisories related to recreational water contact 

are posted by the Department of Human Services Public Health Division, Office 

of Environmental Public Health. (See 

http://www.oregon.gov/DHS/ph/hab/index.shtml)
May 12, 2011 Page 19

 Algae: Documented evidence that algae, including periphyton (attached algae) or 

phytoplankton (floating algae), are causing other standards to be exceeded (e.g. 

pH, chlorophyll a, or dissolved oxygen) or impairing a beneficial use.

If pollutants are identified as contributing to excessive or harmful growth of aquatic 

weeds or algae, the water body will remain in Category 5 for aquatic weeds or algae until 

TMDLs for those pollutants are approved.

Category 4: Water Quality Limited, TMDL Not Needed

 TMDLs for specific pollutants have been completed and approved to address the 

excessive or harmful aquatic weed or algae growth in a water body (Category 

4A);

 Another control mechanism such as an aquatic vegetation management plan is in 

place and is being implemented to control plant growth (Category 4B); or

 Adequate information indicates that plant proliferation is not due to pollutants or 

is a natural condition (Category 4C).

Category 3: Insufficient Data

Available data for the water body are not sufficient to determine if the narrative criterion 

is exceeded.

(See NOTE on Phosphate Phosphorus Benchmark under Toxic Substances.)

Category 2: Attaining

Not applicable.

TIME PERIOD:

Annual

DATA REQUIREMENTS:

Information, data, or health advisories since 1999.
May 12, 2011 Page 20

POLLUTANT: Bacteria - E. coli (Escherichia coli)

(Freshwaters and Estuarine Waters Other 

than Shellfish Growing Waters)

BENEFICIAL USES AFFECTED: Water Contact Recreation

NARRATIVE CRITERION: OAR 340-041-0009(4)

NUMERIC CRITERION: OAR 340-041-0009(1)(a) and (5)

340-041-0009

Bacteria

(1) Numeric Criteria: Organisms of the coliform group commonly associated with 

fecal sources (MPN or equivalent membrane filtration using a representative 

number of samples) may not exceed the criteria described in paragraphs (a) and 

(b) of this paragraph:

(a) Freshwaters and Estuarine Waters Other than Shellfish Growing 

Waters: 

(A) A 30-day log mean of 126 E. coli organisms per 100 

milliliters, based on a minimum of five (5) samples; 

(B) No single sample may exceed 406 E. coli organisms per 100 

milliliters.

(4) Bacterial pollution or other conditions deleterious to waters used for domestic 

purposes, livestock watering, irrigation, bathing, or shellfish propagation, or 

otherwise injurious to public health may not be allowed;

(5) Effluent Limitations for Bacteria: Except as allowed in subsection (c) of this 

section, upon NPDES permit renewal or issuance, or upon request for a permit 

modification by the permittee at an earlier date, effluent discharges to freshwaters, 

and estuarine waters other than shellfish growing waters may not exceed a 

monthly log mean of 126 E. coli organisms per 100 ml. No single sample may 

exceed 406 E. coli organisms per 100 ml. However, no violation will be found, 

for an exceedance if the permittee takes at least five consecutive re-samples at 

four-hour intervals beginning as soon as practicable (preferably within 28 hours) 

after the original sample was taken and the log mean of the five re-samples is less 

than or equal to 126 E. coli. The following conditions apply:

ASSIGNMENT OF ASSESSMENT CATEGORY:

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

A 30-day log mean greater than 126 E. coli organisms per 100 ml based on a minimum of 

five (5) samples, or more than 10% of the samples exceed 406 E. coli organisms per 100 

ml, with a minimum of at least two exceedences.

Category 4: Water Quality Limited, TMDL Not Needed

TMDLs needed to attain applicable water quality standards have been approved

(Category 4A), other pollution control requirements are expected to address pollutant and 

will attain water quality standards (Category 4B), or impairment is not caused by a 

pollutant (Category 4C).
May 12, 2011 Page 21

Category 3: Insufficient Data

Less than 5 samples are available to evaluate for the season of interest, or 5 to 9 samples 

for the season of interest with 1 sample exceeding 406 E. coli organisms per 100 

milliliters.

Category 3B: Insufficient Data – Potential Concern

Less than 5 samples are available to evaluate for the season of interest, with 2 or more 

samples exceeding 406 E. coli organisms per 100 milliliters.

Category 2: Attaining

The 30-day log mean is equal to or less than 126 E. coli organisms per 100 ml based on a 

minimum of five (5) samples, and, if data from 10 or more samples are available, 90% of 

the samples are below 406 E. coli organisms per 100 ml. If data from 5 to 9 samples are 

available, no exceedences of 406 E. coli organisms per 100 ml.

If data are insufficient to calculate a 30-day log mean, then, for 10 or more samples, 90% 

of the samples are below 406 E. coli organisms per 100 ml; or for 5 to 9 samples, no 

samples greater than 406 E. coli organisms per 100 ml.

TIME PERIOD:

Summer: June 1 through September 30 (period of highest use for water contact 

recreation). (A summer 30-day log mean is calculated for sampling dates beginning on 

May 17 through September 16.)

Fall-Winter-Spring (FWS): October 1 through May 31. (A FWS 30-day log mean is 

calculated for sampling dates beginning September 17 through May 16.)

DATA REQUIREMENTS:

Data collected since 1999. A minimum of 5 representative data points available per site 

collected on separate days for each time period of interest. The numeric value of results 

reported as the Minimum Reporting Level (MRL) was used to calculate the 30-day log 

mean.

NOTES:

The E. coli numeric criteria are applicable to protect water contact beneficial use in 

freshwaters and estuarine waters. Estuarine waters are defined in OAR 340-041-0002(22) 

to mean all mixed fresh and oceanic water in estuaries or bays from the point of oceanic 

water intrusion inland to a line connecting the outermost points of the headlands or 

protective jetties. For the 2010 review of water quality data, the inland extent of estuarine 

waters was identified where recorded specific conductivity measurements were above 

200 uS/cm. The E. coli numeric criteria are applicable to effluent discharges to 

freshwaters and estuarine waters.

The E. coli numeric criteria are not applied in marine waters. 
May 12, 2011 Page 22

The bacteria standard was changed in 1996 to use E. coli as the indicator organism for 

water contact recreation protection, replacing the previous standard based on fecal 

coliform. Only the current E. coli standard is applied in freshwaters and estuarine waters

for data reviewed for the 2010 assessment. Listings in previous years may have identified

freshwater water bodies as water quality limited using fecal coliform as the indicator. If 

data evaluated for the 2010 assessment show the current E. coli criteria for freshwater are 

met, the water body will be de-listed for older fecal coliform listings. The listings are 

retained if no data for E. coli are available for the 2010 evaluation, or if E. coli is also 

listed.

Estuarine waters are also considered coastal recreation water subject to the federal water 

quality criteria based on Enterococci, and are additionally presumed to be potential 

shellfish growing waters, subject to the fecal coliform criteria to protect that beneficial 

use. The assessment for these standards is discussed in the next sections.
May 12, 2011 Page 23

POLLUTANT: Bacteria - Enterococci

(Coastal Recreation Waters including 

Coastal Estuaries)

6

BENEFICIAL USES AFFECTED: Water Contact Recreation

NUMERIC CRITERION: 40 CFR Part 131.41

EPA promulgated water quality criteria for 

Oregon marine coastal recreation waters 

(effective 12/16/2004)

40 CFR Part 131.41

(c) EPA’s section 304(a) ambient water quality criteria for bacteria.

(2) Marine waters:

Indicator Geometric 

mean

Single sample maximum (per 100 ml)

Moderate use coastal recreation waters

Enterococci 35/100 ml 158

ASSIGNMENT OF ASSESSMENT CATEGORY:

EPA recommends using the geometric mean as the relevant criteria for 303(d) listing 

purposes.7The single sample maximum is a statistical construct to allow decisions for 

beach advisories based on small data sets. Marine waters in coastal Oregon have not been 

designated for a specific level of recreational use. The single sample maximum criteria 

for moderate use coastal recreation waters is currently used by the Oregon Department of 

Human Services Public Health Division, Office of Environmental Public Health’s 

Oregon Beach Monitoring Program to trigger a water contact advisory. (See 

http://oregon.gov/DHS/ph/beaches/status.shtml)

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

A geometric mean for samples collected over a seasonal sampling period greater than 35

Enterococci per 100 ml based on a sample set of 5 or more samples.

Category 4: Water Quality Limited, TMDL Not Needed

TMDLs needed to attain applicable water quality standards have been approved

(Category 4A), other pollution control requirements are expected to address pollutant and 

will attain water quality standards (Category 4B), or impairment is not caused by a 

pollutant (Category 4C).

 

6

40 CFR Part 131.41 (b) Definitions. (1) Coastal Recreation Waters are the Great Lakes and marine 

coastal waters (including coastal estuaries) that are designated under section 303(c) of the Clean Water Act 

for use for swimming, bathing, surfing, or similar water contact activities. Coastal recreation waters do not 

include inland waters or waters upstream from the mouth of a river or stream having an unimpaired natural 

connection with the open sea.

7 US EPA Office of Water, EPA-823-F-06-013, August 2006, Water Quality Standards for Coastal 

Recreation Waters: Using Single Sample Maximum Values in State Water Quality Standards
May 12, 2011 Page 24

Category 3: Insufficient Data

Less than 5 samples are available for evaluation for a seasonal sampling period.

Category 3B: Insufficient Data – Potential Concern

Less than 5 samples are available for a seasonal sampling period, and one or more 

samples exceeds the single sample maximum of 158 Enterococci per 100 ml, or the 

Oregon Beach Monitoring Program has issued one or more advisories based on 

monitoring results for Enterococci in a seasonal sampling period.

Category 2: Attaining

The geometric mean for samples collected over a seasonal sampling period is equal or 

less than 35 Enterococci per 100 ml.

TIME PERIOD:

Summer: May 1 through September 30 (period of highest use for water contact 

recreation)

Winter: October 1 through April 30

DATA REQUIREMENTS:

Data collected since 1999. A minimum of 5 representative data points available per site 

collected on separate days for each seasonal time period in a given year. For results 

reported as the Minimum Reporting Level (<MRL), the numeric value of the MRL was 

used to calculate the geometric mean .

NOTES:

Coastal recreation waters for this assessment are identified as all marine waters and 

coastal estuaries. Coastal recreation waters do not include inland waters or waters 

upstream from the mouth of a river or stream having an unimpaired natural connection 

with the open sea.

The Oregon Beach Monitoring Program has identified 92 coastal beaches in Oregon. 

Each of these beaches is assigned a beach name and beach identification number that are 

used in reporting to EPA. For the Water Quality Report , the identified coastal beaches 

were used as the assessment units and defined as segments along the Pacific Ocean or an 

estuarine river location.

The Oregon Beach Monitoring Program may issue pre-cautionary advisories based on 

heavy rainfall, flooding, or sewage spills. These advisories are not included in the data 

summarized in this assessment.
May 12, 2011 Page 25

POLLUTANT: Bacteria – Fecal Coliform

(Marine Waters and Estuarine Shellfish 

Growing Waters)

BENEFICIAL USES AFFECTED: Shellfish Growing

Water Contact Recreation

NARRATIVE CRITERION: OAR 340-041-0007(11) and 

OAR 340-041-0009(4)

340-041-0007

Statewide Narrative Criteria

(11) The creation of tastes or odors or toxic or other conditions that are 

deleterious to fish or other aquatic life or affect the potability of drinking water or 

the palatability of fish or shellfish may not be allowed;

NUMERIC CRITERION: OAR 340-041-0009(1)(b)

340-041-0009

Bacteria

(1) Numeric Criteria: Organisms of the coliform group commonly associated with 

fecal sources (MPN or equivalent membrane filtration using a representative 

number of samples) may not exceed the criteria described in paragraphs (a) and 

(b) of this paragraph: 

(b) Marine Waters and Estuarine Shellfish Growing Waters: A fecal 

coliform median concentration of 14 organisms per 100 milliliters, with 

not more than ten percent of the samples exceeding 43 organisms per 100 

ml. 

(4) Bacterial pollution or other conditions deleterious to waters used for domestic 

purposes, livestock watering, irrigation, bathing, or shellfish propagation, or 

otherwise injurious to public health may not be allowed;

ASSIGNMENT OF ASSESSMENT CATEGORY:

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

For a datasets of less than 30 samples, a minimum of 2 exceedences of 43 organisms/100 

ml. For datasets with greater than 30 samples, 10% of the samples must exceed 43 

organisms/100mL.

OR, for datasets with a minimum of 5 samples, the median value is greater than 14 

organisms/100 ml.

Category 4: Water Quality Limited, TMDL Not Needed

TMDLs needed to attain applicable water quality standards have been approved

(Category 4A), other pollution control requirements are expected to address pollutant and 

will attain water quality standards (Category 4B), or impairment is not caused by a 

pollutant (Category 4C).
May 12, 2011 Page 26

Category 3: Insufficient Data

Less than 5 samples available for analysis, or 5 to 9 samples with 1 exceedence and the 

median is 14 organisms/100 ml or less.

Category 3B: Insufficient Data – Potential Concern

Less than 5 samples available to evaluate, with 2 or more samples exceeding 43 

organisms per 100 milliliters.

Category 2: Attaining

A minimum number of 5 samples per site, with 90% of the samples less than 43 

organisms/100 ml and the median value of 14 organisms/100 ml or less.

TIME PERIOD:

Annual

DATA REQUIREMENTS:

Data collected since 1999. A minimum of 5 representative samples per site collected on 

separate days. The numeric value of results reported as the Minimum Reporting Level 

(MRL) was used to calculate the median concentration . Data evaluated for marine and 

estuarine waters.

NOTES:

DEQ has determined that fecal coliform water quality criteria should be applied to marine 

and estuarine waters that support recreational shellfish harvesting as well as commercial 

shellfish harvesting (Minutes from the Estuary Workgroup Meeting, DEQ, Newport, 

Oregon, July 13, 2001).

Marine waters are defined in OAR 340-041-0002(34) as all oceanic, offshore water 

outside of estuaries or bays and within the territorial limits of Oregon. Estuarine waters 

are defined in OAR 340-041-0002(22) as mixed fresh and oceanic water in estuaries or 

bays from the point of oceanic water intrusion inland to a line connecting the outermost 

points of the headlands or protective jetties. For the 2010 review of water quality data, 

the inland extent of estuarine waters was identified where recorded specific conductivity

measurements were above 200 uS/cm. However, coastal lakes were not included as 

estuarine shellfish growing waters for this assessment.

To protect water contact recreation as a beneficial use, the bacteria standard was changed 

in 1996 to use E. coli as the indicator organism, replacing the previous standard based on 

fecal coliform. However, assessments in previous years may have identified freshwater 

water bodies as water quality limited for water contact recreation using fecal coliform

data. These listings are retained unless data for E. coli are available for evaluation for the 

2010 assessment. If data show the current E. coli criteria are met, the water body will be 

de-listed for water contact recreation impairments.

Marine and estuarine waters are subject to the federal water quality criteria based on 

Enterococci that protects water contact recreation in coastal recreation waters. The 
May 12, 2011 Page 27

assessment of coastal recreation waters is discussed in the previous section on 

Enterococci.
May 12, 2011 Page 28

POLLUTANT: Biocriteria

BENEFICIAL USES AFFECTED: Aquatic Life

NUMERIC CRITERION: None

NARRATIVE CRITERION: OAR 340-041-0011

340-041-0011

Biocriteria

Waters of the State must be of sufficient quality to support aquatic species 

without detrimental changes in the resident biological communities.

NARRATIVE ASSESSMENT PROTOCOL:

Detrimental changes in resident biological communities are a form of pollution.8,9EPA 

guidance recommends using biological community assessments as an indicator for 

aquatic life beneficial use support.10 This protocol will be used to implement Oregon’s 

narrative standard for Biocriteria for the 2010 Water Quality Assessment. The protocol 

applies numeric benchmarks to evaluate the integrity of aquatic biological communities.

Biological assessments look at conditions in the biological communities, but do not by 

themselves indicate if changes are related to pollutants, or identify which pollutant should 

be addressed by point source or other controls through a Total Maximum Daily Load.

EPA guidance recommends listing waters with aquatic use impairments as Category 5 

even if the pollutant is not known.11 This protocol outlines the process and assessment 

category assignment that Oregon will use for the 2010 Integrated Report to apply the 

narrative criterion.

This protocol is based on biological assemblage information for freshwater 

macroinvertebrates collected by DEQ at reference sites throughout Oregon. Freshwater 

macroinvertebrates include insects, crustaceans, snails, clams, worms, mites, etc. DEQ

identifies sites in a given region that are least disturbed by anthropogenic activities and 

uses these as reference sites.12 Biological assessment tools use information from these 

reference sites to predict the variety and number of aquatic life species expected in 

Oregon streams and to make inferences about the biological condition of the waters.13

 

8

Federal Water Pollution Act Section 502(19) (33 U.S.C 1362) (Clean Water Act)

9 Oregon Administrative Rules 340-041-0002(39)

10 US EPA, July 29, 205, Guidance for 2006 Assessment, Listing and Reporting Requirements Pursuant to 

Sections 303(d), 305(b) and 314 of the Clean Water Act, page 41.

11 US EPA, July 29, 205, Guidance for 2006 Assessment, Listing and Reporting Requirements Pursuant to 

Sections 303(d), 305(b) and 314 of the Clean Water Act, page 60.

12 Drake, D., April 2004, Selecting Reference Condition Sites - An Approach for Biological Criteria and 

Watershed Assessment, ODEQ Technical Report WSA04-002. 

http://www.deq.state.or.us/lab/techrpts/docs/WSA04002.pdf

13 Stoddard,J.L., et.al., 2006. Setting Expectations for the Ecological Condition of Streams: The Concept of 

Reference Condition. Ecological Applications. 16(4): 1267-1276
May 12, 2011 Page 29

Assessing Macroinvertebrate Communities

To assess the biological integrity of macroinvertebrate communities, DEQ uses a 

statistical method called a multivariate predictive model.14 Using data from reference 

sites, the model describes the number and types of macroinvertebrates that are expected 

to be in a water body when the water is in least disturbed conditions. Reference sites are 

grouped by predictor variable factors that are not affected by human activities (e.g., 

sampling date, ecoregion, longitude, elevation, precipitation, or air temperature). DEQ

has developed a model specifically for Oregon, but similar model approaches are used for 

bioassessments in the United Kingdom (RIVPACS), Australia (AusRIVas), Canada 

(BEAST), and in broad areas in the United States (typically called RIVPACS models, 

though different from the U. K. models).

DEQ has developed the PREDictive Assessment Tool for ORegon, or PREDATOR, to 

assess the macroinvertebrate communities in Oregon’s perennial, wadeable streams.

PREDATOR analyzes data from reference sites grouped into three regions in Oregon and 

models the expected assemblage. Information from a sampling site can be compared to 

the macroinvertebrate assemblage predicted by the model and an assessment made about 

how different the observed assemblage is from the expected or reference assemblage.

Data collected at a sampling site is used to generate a number for the observed versus 

expected (O/E) macroinvertebrate taxa. This number represents the “missing” taxa at a 

site, and can be expressed as “% taxa loss”.

For the 2010 assessment, DEQ has selected values of % taxa loss to assign a status 

category to a water body. The benchmark values are indicators of differences from 

reference conditions that may indicate detrimental changes to biological communities and 

an impairment in aquatic life use support that violates the narrative standard. A 

discussion of the scientific basis for the model development, statistical analysis of 

reference site data, and selection of numeric benchmark values is given in a separate 

technical paper.11

ASSIGNMENT OF ASSESSMENT CATEGORY:

Benchmark values are expressed in terms of the percent of taxa not found in a site 

assemblage compared to the expected assemblage predicted by the PREDATOR model.

A full discussion of the statistical basis for the specific benchmark values in terms of the 

reference site distributions in different regions in Oregon is provided in a separate

technical paper. 11

Category 3c: Impairing Pollutant Unknown

Comparison to the assessment benchmark shows the biological community is impaired, 

but the pollutant causing the impairment is unknown, and a TMDL cannot be developed.

 

14 Hubler, S., July 2008, PREDATOR: Development and Use of RIVPACS-type Macroinvertebrate Models 

to Assess the Biotic Condition of Wadeable Oregon Streams, Technical Report DEQ08-LAB-0048-TR
May 12, 2011 Page 30

Macroinvertebrate sampling data from perennial, wadeable streams evaluated by DEQ

using the PREDATOR model showing:

 ≥ 15% taxa loss in the Marine Western Coastal Forest (MWCF) region, 

 ≥ 22% taxa loss in the Western Cordillera and Columbia Plateau (WCCP) region, 

or 

 ≥ 50% taxa loss in the Northern Basin and Range (NBR) region.

Category 4: Water Quality Limited, TMDL Not Needed

In some water bodies, DEQ has information relating specific pollutants to the condition 

of the biological communities in the water body. Where data are available identifying a 

specific pollutant as the cause of detrimental changes to biological communities, and a 

TMDL has been approved with load allocations for the pollutant, the water body will be 

placed in Category 4 if no additional TMDLs are needed. Water bodies will also be 

placed in Category 4 for biological criteria if adequate information is available to indicate 

that detrimental changes to biological communities are not due to a pollutant.

Category 3B: Insufficient Data – Potential Concern

Some macroinvertebrate sampling data from perennial, wadeable streams evaluated using 

the PREDATOR model are inconclusive and are insufficient to assign a status category 

until additional information is collected.

Macroinvertebrate sampling data from perennial, wadeable streams evaluated by DEQ

using the PREDATOR model showing:

 8% to 14% taxa loss or > 24% taxa gain in the Marine Western Coastal Forest 

(MWCF) region, 

 8% to 21% taxa loss or > 23% taxa gain in the Western Cordillera and Columbia 

Plateau (WCCP) region, or 

 25% to 49% taxa loss in the Northern Basin and Range (NBR) region.

Results showing taxa loss in these ranges could be due to sampling error or modeling 

error and may be over or under-estimating taxa loss. A large gain of observed taxa over 

expected may indicate more natural diversity, or may indicate disturbance that has 

enhanced diversity.15 Additional samples are necessary to better assess biological 

conditions. A minimum of 5 replicate samples should be collected to provide sufficient 

data for status classification. The stream is a potential concern until more information is 

evaluated.

Category 2: Attaining

Macroinvertebrate sampling data from perennial, wadeable streams evaluated by DEQ

using the PREDATOR model showing:

 0% to 8% taxa loss or 0% to 24% taxa gain in the Marine Western Coastal Forest 

(MWCF) region, 

 

15 Ward, J.W, and Stanford, J.A., 1983, Intermediate-Disturbance Hypothesis: An Explanation for Biotic 

Diversity Patterns in Lotic Ecosystems. In Dynamics of Lotic Systems, Ann Arbor Science, Ann Arbor, 

MI, pages 347-356.
May 12, 2011 Page 31

 0% to 7% taxa loss or 0% to 23% taxa gain in the Western Cordillera and 

Columbia Plateau (WCCP) region, or 

 < 25% taxa loss in the Northern Basin and Range (NBR) region.

DATA REQUIREMENTS:

Site sample data must be collected during or after 1998 to be comparable to the reference 

site data (1998 to 2004) that is used in the PREDATOR model. Site samples must be 

collected within the model season of June 1 through October 15. Field duplicates and 

seasonal replicate samples are averaged to account for sampling and seasonal variability.

Site sample data must be collected using standard field methods and identified to 

appropriate taxonomic levels, as described in the DEQ Mode of Operations Manual, or 

equivalent protocols used throughout the Pacific Northwest.

16 The standard method for 

macroinvertebrate sampling requires collecting organisms from specific habitats within a 

specified size reach of a stream. The data are evaluated to generate one sample result in 

the PREDATOR model.

One sample result is sufficient to evaluate for the assessment using the benchmarks 

developed from the PREDATOR model. If samples from multiple years are available, the 

most recent sample result of Category 2 or Category 5 will determine the site status. If 

the most recent sample result is Category 2 and a previous sample is Category 5, the site 

status will be Category 3b. Recent Category 2 sample results must outnumber earlier 

Category 5 sample results for the site status to be considered Category 2.

When results for replicate site samples are collected to clarify inconclusive results 

(Category 3b), a minimum of 5 samples is required to achieve the target statistical 

confidence. The site will be assigned a status category if 3 out of 5 replicate samples 

show results in the Category 2 or Category 5 ranges. Replicate samples must be collected 

in the same sampling season, in the same reach, or in adjacent and comparable reaches.

DE-LISTING:

Once TMDLs are approved for pollutants that will also improve biological conditions, 

water bodies may be de-listed for biocriteria. These waters will be placed in Category 4:

Water Quality Limited, TMDL Not Needed if no additional TMDLs are needed.

Water bodies may be de-listed for biocriteria based on multiple site sampling events 

showing results that are attaining benchmarks. A minimum of 5 samples must be 

collected in the same sampling season and in the same or adjacent and comparable 

reaches, with 3 out of 5 samples showing results that attain appropriate benchmarks.

These waters will be placed in Category 2: Attaining.

 

16 ODEQ, 2009, Mode of Operations Manual, Version 3.2, DEQ03-LAB-0036-SOP, 

http://www.deq.state.or.us/lab/techrpts/docs/DEQ03LAB0036SOP.pdf
May 12, 2011 Page 32

SEGMENTATION:

General segmentation protocols will be followed (Appendix 1). The status category from 

one sampling site will apply to the sampling reach and upstream portions of the 

wadeable, perennial stream. A minimum segment length of 0.6 miles will be imposed 

when multiple sample sites are closely located within a small stream reach. Given the 

sampling design and field protocols, assessment segments less than 0.6 miles are likely to 

impose artificial divisions that are not true representations of stream conditions.

BENCHMARK SUMMARY:

Table 1. Macroinvertebrate communities assessment benchmarks for perennial, 

wadeable streams.

PREDATOR 

Model Region

Impaired

Category 3c:

Impairing Pollutant 

Unknown

Category 3b:

Insufficient Data

Potential Concern

Category 2:

Attaining

Marine Western 

Coastal Forest 

≥ 15% taxa loss 9% - 14% taxa loss or

> 24% taxa gain

0% - 8% taxa loss or

0% - 24% taxa gain

PREDATOR score ≤ 0.85 PREDATOR score

0.86 to 0.91 or > 1.24

PREDATOR score 

0.92 to 1.24

Western 

Cordillera and 

Columbia 

Plateau

≥ 22% taxa loss 8% - 21% taxa loss or

> 23% taxa gain

0% - 7% taxa loss or

0% - 23% taxa gain

PREDATOR score ≤ 0.78 PREDATOR score

0.79 to 0.92 or > 1.23

PREDATOR score 

0.93 to 1.23

Northern Basin 

and Range

≥ 50% taxa loss 25% - 49% taxa loss < 25% taxa loss

PREDATOR score ≤ 0.50 PREDATOR score

0.49 to 0.75

PREDATOR score > 0.75
May 12, 2011 Page 33

POLLUTANT: Chlorophyll a

(Nuisance Phytoplankton Growth)

BENEFICIAL USES AFFECTED: Water Contact Recreation

Aesthetics

Fishing

Water Supply

Livestock Watering

NUMERIC CRITERION: OAR 340-041-0019

340-041-0019

Nuisance Phytoplankton Growth

(1) (a) The following values and implementation program must be applied to 

lakes, reservoirs, estuaries and streams, except for ponds and reservoirs less than 

ten acres in surface area, marshes and saline lakes: 

(b) The following average Chlorophyll a values must be used to identify 

water bodies where phytoplankton may impair the recognized beneficial 

uses:

(A) Natural lakes that thermally stratify: 0.01 mg/1;

(B) Natural lakes that do not thermally stratify, reservoirs, rivers 

and estuaries: 0.015 mg/1; 

(C) Average Chlorophyll a values may be based on the following 

methodology (or other methods approved by the Department): A 

minimum of three samples collected over any three consecutive 

months at a minimum of one representative location (e.g., above 

the deepest point of a lake or reservoir or at a point mid-flow of a 

river) from samples integrated from the surface to a depth equal to 

twice the secchi depth or the bottom (the lesser of the two depths); 

analytical and quality assurance methods must be in accordance 

with the most recent edition of Standard Methods for the 

Examination of Water and Wastewater.

ASSIGNMENT OF ASSESSMENT CATEGORY:

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

The average Chlorophyll a value over three consecutive months exceeds the value 

referenced in the rule. The average must be calculated with at least one sample in each 

month.

Category 4: Water Quality Limited, TMDL Not Needed

 TMDLs for specific pollutants have been completed and approved to address 

nuisance phytoplankton growth and exceedence of chlorophyll a values in a water 

body (Category 4A);

 Another control mechanism such as a control strategy develop and adopted 

according to OAR 340-041-0019(2) is being implemented to control 

phytoplankton growth (Category 4B); or
May 12, 2011 Page 34

 Adequate information indicates that phytoplankton proliferation is not due to 

pollutants or is a natural condition (Category 4C).

Category 3: Insufficient Data

Less than 3 samples available in three consecutive months to calculate an average, or less 

than one sample available in any month of the three consecutive month period.

Category 2: Attaining

The average Chlorophyll a value over three consecutive months is less than the value 

referenced in the rule.

TIME PERIOD:

Summer: June 1 through September 30 or three month periods beginning May through 

August

Fall-Winter-Spring (FWS): October 1 through May 31 or three month periods beginning 

September through April

DATA REQUIREMENTS:

Data collected since 1999. A minimum of three samples collected over any three 

consecutive months (at least one per month) at a minimum of one representative location 

(e.g., above the deepest point of a lake or reservoir or at a point mid flow of a river).

NOTES:

Information on thermally stratified lakes was obtained from the Atlas of Oregon Lakes17.

Lakes are identified by an LLID assigned to a point at the center of the water body. They 

may also be identified with an LLID for a stream which flows into or out of the lake, and 

river miles are assigned at those points on the stream line.

Saline lakes were identified in coastal areas and Oregon Closed Basins where recorded 

specific conductivity measurements were generally above 200 uS/cm.

 

17 Johnson, D.M., Petersen, R.R., Lycan, D.R., Sweet, J.W., Neuhaus, M.E., Schaedel, A.L., 1985, Atlas of 

Oregon Lakes: Corvallis, OR, Oregon State University Press, 317 p.
May 12, 2011 Page 35

POLLUTANT: Dissolved Oxygen

BENEFICIAL USES AFFECTED: Fish and Aquatic Life

Salmon and Steelhead Spawning

Resident Trout Spawning

Cold-Water Aquatic Life

Cool-Water Aquatic Life

Warm-Water Aquatic Life

Estuarine Water

NUMERIC CRITERION: OAR 340-041-0016

340-041-0016

Dissolved Oxygen

Dissolved oxygen (DO): No wastes may be discharged and no activities must be 

conducted that either alone or in combination with other wastes or activities will 

cause violation of the following standards: The changes adopted by the 

Commission on January 11, 1996, become effective July 1, 1996. Until that time, 

the requirements of this rule that were in effect on January 10, 1996, apply: 

(1) For water bodies identified as active spawning areas in the places and times 

indicated on the following Tables and Figures set out in OAR 340-041-0101 to 

340-041-0340: Tables 101B, 121B, 180B, 201B and 260B, and Figures 130B, 

151B, 160B, 170B, 220B, 230B, 271B, 286B, 300B, 310B, 320B, and 340B, (as 

well as any active spawning area used by resident trout species), the following 

criteria apply during the applicable spawning through fry emergence periods set 

forth in the tables and figures: 

(a) The dissolved oxygen may not be less than 11.0 mg/l. However, if the 

minimum intergravel dissolved oxygen, measured as a spatial median, is 

8.0 mg/l or greater, then the DO criterion is 9.0 mg/l; 

(b) Where conditions of barometric pressure, altitude, and temperature 

preclude attainment of the 11.0 mg/l or 9.0 mg/l criteria, dissolved oxygen 

levels must not be less than 95 percent of saturation; 

(c) The spatial median intergravel dissolved oxygen concentration must 

not fall below 8.0 mg/l. 

(2) For water bodies identified by the Department as providing cold-water aquatic 

life, the dissolved oxygen may not be less than 8.0 mg/l as an absolute minimum. 

Where conditions of barometric pressure, altitude, and temperature preclude 

attainment of the 8.0 mg/l, dissolved oxygen may not be less than 90 percent of 

saturation. At the discretion of the Department, when the Department determines 

that adequate information exists, the dissolved oxygen may not fall below 8.0 

mg/l as a 30-day mean minimum, 6.5 mg/l as a seven-day minimum mean, and 

may not fall below 6.0 mg/l as an absolute minimum (Table 21); 

(3) For water bodies identified by the Department as providing cool-water 

aquatic life, the dissolved oxygen may not be less than 6.5 mg/l as an absolute 

minimum. At the discretion of the Department, when the Department determines 

that adequate information exists, the dissolved oxygen may not fall below 6.5 
May 12, 2011 Page 36

mg/l as a 30-day mean minimum, 5.0 mg/l as a seven-day minimum mean, and 

may not fall below 4.0 mg/l as an absolute minimum (Table 21); 

(4) For water bodies identified by the Department as providing warm-water 

aquatic life, the dissolved oxygen may not be less than 5.5 mg/l as an absolute 

minimum. At the discretion of the Department, when the Department determines 

that adequate information exists, the dissolved oxygen may not fall below 5.5 

mg/l as a 30-day mean minimum, and may not fall below 4.0 mg/l as an absolute 

minimum (Table 21); 

(5) For estuarine water, the dissolved oxygen concentrations may not be less than 

6.5 mg/l (for coastal water bodies); 

(6) For ocean waters, no measurable reduction in dissolved oxygen concentration 

may be allowed. 

ASSIGNMENT OF ASSESSMENT CATEGORY:

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

Greater than 10 percent of the samples exceed the appropriate criterion and a minimum of 

at least two exceedences of the criterion for the time period of interest.

Category 4: Water Quality Limited, TMDL Not Needed

TMDLs needed to attain applicable water quality standards have been approved

(Category 4A), other pollution control requirements are expected to address pollutant and 

will attain water quality standards (Category 4B), or impairment is not caused by a 

pollutant (Category 4C).

Category 3: Insufficient Data

Less than 5 samples for the time period of interest, or 5 to 9 samples for the time period 

of interest with 1 exceedence.

Category 2: Attaining

For 10 or more samples in the time period of interest, greater than 90% of the samples 

meet the appropriate criterion. For 5 to 9 samples in the time period of interest, there are 

no exceedences of the appropriate criteria.

TIME PERIOD:

Spawning and Non-Spawning Time Periods

In designated salmon and steelhead spawning areas, the spawning criterion will be 

applied during the time periods indicated in tables and figures referenced in OAR 340-

041-0016(1). During the non-spawning part of the year in these areas, the cold or cool 

water criterion is applied depending on ecoregion according to a policy set out in a June 

22, 1998 letter from DEQ to EPA, Region 10 (Appendix 3, p. 3-4).

In areas designated in OAR 340-041 Table 190B for Lahontan trout use, spawning is 

assumed to occur throughout the range during the time periods indicated on the table.

During the non-spawning part of the year in these areas, the cool water criterion is 

applied based on ecoregion according to a policy set out in a June 22, 1998 letter from 

DEQ to EPA, Region 10 (Appendix 3).
May 12, 2011 Page 37

In areas designated as bull trout (char) spawning and juvenile rearing in tables and figures 

referenced in OAR 340-041-0016(1), the spawning criterion will be applied during the 

time periods set out in a February 2, 2004 letter from DEQ to EPA, Region 10 (Appendix 

4) and summarized in Table 4. During the non-spawning part of the year in these areas, 

the cold water criterion is applied.

Table 4: Bull Trout Spawning Time Periods

Basin Subbasin Spawning Period

South Willamette August 15 – May 30

John Day September 1 – April 30

Umatilla September 1 – April 30

Walla Walla September 1 – April 30

Grande Ronde Upper Grande Ronde September 1 – April 15

Wallowa September 1 – May 15

Wenaha August 15 – March 31

Imnaha August 15 – May 31

Hood August 15 – May 15

Deschutes August 15 – May 15

Powder August 15 – May 15

Malheur August 15 – May 30

Klamath August 15 - May 30

Detailed information on spawning locations and spawning time periods is not available 

for other resident trout species such as redband, rainbow, westslope and cutthroat trout.

Therefore, in areas not designated as salmon and steelhead spawning use or Lahontan 

trout use, DEQ assumes resident trout spawning occurs. The spawning criterion will be 

applied for resident trout during the time periods indicated in a policy set out in a 

February 2, 2004 letter from DEQ to EPA Region 10 (Appendix 4). In this letter, the 

spawning time periods were linked to the designated fish uses such as trout rearing, core 

cold water, and char (bull trout) spawning and rearing. Table 5 summarizes the assumed 

spawning time periods for resident trout in streams with designated fish uses.

Table 5: Resident Trout Spawning Time Periods

Designated Fish Use Resident Trout Spawning

Salmon and trout rearing and 

migration

January 1 – May 15

Redband trout January 1 – May 15

Core cold water habitat and 

upstream trout rearing water

January 1 – June 15

Bull trout spawning and juvenile 

rearing

January 1 – June 15

Salmon and Steelhead Migration 

Corridors

Assume not suitable for spawning
May 12, 2011 Page 38

Spawning time periods for resident trout and bull trout are combined in areas where the 

designated fish use is bull trout spawning and juvenile rearing. For example, in the John 

Day basin where bull trout spawning occurs, the resident trout spawning time period 

(Table 5: January 1 – June 15) and the bull trout spawning time period (Table 4: 

September 1 – April 30) are combined and the spawning criterion is applied during the 

time period September 1 through June 15.

DATA REQUIREMENTS:

Data collected since 1993. A minimum of 5 representative data points available per site 

collected on separate days per applicable time period. The daily mean of continuous 

dissolved oxygen data is calculated and represents one data point. Any combination of 5 

days of continuous or grab sample data in the time period is acceptable.

NOTES:

Cold or Cool Water Criteria:

During non-spawning time periods, cold water criteria for dissolved oxygen are applied 

in areas designated for core cold water fish use in tables and figures referenced in OAR 

340-041-0101 through OAR 340-041-0340.

Cold water criteria are also applied in designated bull trout spawning and rearing areas in 

non-spawning time periods.

Cool water criteria for dissolved oxygen are applied in areas designated specifically for 

cool water species fish use in tables and figures referenced in OAR 340-041-0101 

through OAR 340-041-0340.

Cool water criteria for dissolved oxygen are also applied in non-spawning time periods in 

areas designated as salmon and trout migration corridors (no rearing) on tables and 

figures referenced in OAR 340-041-0101 through OAR 340-041-0340.

In non-spawning time periods where the designated fish use is salmon and trout rearing 

and migration or redband and Lahontan cutthroat trout, the cold or cool water criteria 

apply based on the ecoregion where the sampling site is located. This policy is described 

in a June 22, 1998 letter from DEQ to EPA, Region X (Appendix 3). The ecoregions are 

described in: Omernik, J. and Gallant, A., 1986, Ecoregions of the Pacific Northwest, 

EPA/600/3-86/033.

Warm Water Criteria:

The warm water criteria are applied to waters identified in OAR 340-041 Table 190B as 

supporting borax lake chub.

Lakes:

Unless designated as salmon and steelhead spawning areas, natural lakes and reservoirs 

are not considered spawning habitat. The applicable cold or cool water criteria are

applied year round.
May 12, 2011 Page 39

Estuarine Criteria:

The estuarine water criterion for dissolved oxygen applies for samples taken in estuarine 

conditions. The spawning criteria is not applied for resident trout, but is applied for

designated salmon and steelhead spawning periods. DEQ used specific conductivity

measurements as an indicator for estuarine conditions. This indicator was chosen after

reviewing specific conductivity measurements collected from coastal waters. As shown

in Figures 4 through 6, the measured specific conductivity is generally lower than 200 

uS/cm at river locations where salt water is not present.

For dissolved oxygen data collected in the coastal waters of the North Coast, Mid Coast, 

South Coast, Rogue and Umpqua Basins, the specific conductivity of each sample was 

also evaluated. For continuous data, the daily mean specific conductivity was calculated.

If the recorded specific conductivity was greater than 200 uS/cm, the estuarine dissolved 

oxygen criterion of 6.5 mg/L was applied. If the recorded specific conductivity was less 

than 200 uS/cm, the appropriate freshwater criteria were applied. Data collected in noncoastal waters was evaluated using the appropriate freshwater criteria.

The spawning criterion during assumed resident trout spawning time periods was not 

applied in sections of a water body where data indicated estuarine conditions.

Figure 4: Specific conductivity Measured in Columbia River

Conductivity (uS/cm) on the Columbia River

0

500

1000

1500

2000

2500

3000

3500

0.0 50.0 100.0 150.0 200.0 250.0 300.0 350.0

River Mile

Conductivity (uS/cm)
May 12, 2011 Page 40

Figure 5: Specific conductivity Measured in Rogue River

Conductivity (uS/cm) of the Rogue River

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0

River Mile Specific conductance (uS/cm)

Figure 6: Specific conductivity Measured in Coquille River

 Specific conductance on the Coquille River

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0

River Mile Spec Conductance (uS/cm)

Summary:
May 12, 2011 Page 41

The following flow chart (Figure 9) illustrates the evaluation process for dissolved 

oxygen data collected from Oregon water bodies.

Figure 9: Evaluation of Dissolved Oxygen Data

Yes

Yes

Yes

Yes

Yes Yes

No

No

No No

No

Yes

Apply warmwater dissolved 

oxygen criterion 

(5.5 mg/L)

Apply spawning 

dissolved 

oxygen criterion 

(11.0 mg/L)

Yes

No

No

Is Lahontan Trout a 

designated fish use in the 

water body?

Is Bull Trout Spawning and 

Juvenile Rearing a 

designated fish use in the 

water body?

Is Core Cold Water Habitat 

or Bull Trout Spawning and 

Juvenile Rearing a 

designated fish use in the 

water body?

Is Cool Water Species or 

Lahontan Trout a designated 

fish use in the water body?

Is Salmon and Steelhead 

Migration Corridor a 

designated fish use in the 

water body?

Apply coldwater 

dissolved

oxygen criterion 

(8.0 mg/L)

Apply coolwater 

dissolved 

oxygen criterion 

(6.5 mg/L)

Apply cold or cool-water

dissolved oxygen 

criterion based on 

ecoregion

(1998 letter) and 

assumed spawning 

period

Is the water body 

a coastal water?

Does sample conductivity 

indicate estuarine conditions 

(> 200 uS/cm)?

Apply estuarine 

dissolved 

oxygen criterion 

(6.5 mg/L)

Is Borax Lake Chub a 

designated fish use in the 

water body?

(OAR 340-041 Table 190B)

Is Salmon and Steelhead 

Spawning a designated 

fish use in the water body?

Is the sample taken during a 

designated (salmon or 

Lahontan trout) or assumed 

(bull trout, resident trout,)

spawning period?

No

No

No

Yes

Yes

Yes

Is the sample taken 

during an assumed 

resident trout spawning 

period (see table)?

No

Yes
May 12, 2011 Page 42

POLLUTANT: pH

BENEFICIAL USES AFFECTED: Resident Fish and Aquatic Life

Water Contact Recreation

NARRATIVE CRITERION: OAR 340-041-0021(2)

NUMERIC CRITERION: Statewide: OAR 340-041-0021

Basin-Specific: OAR 340-041-0101 through 

OAR 340-0410350

340-041-0021

pH

(1) Unless otherwise specified in OAR 340-041-0101 through 340-041-0350, pH 

values (Hydrogen ion concentrations) may not fall outside the following ranges: 

(a) Marine waters: 7.0-8.5; 

(b) Estuarine and fresh waters: See basin specific criteria (OAR 340-041-

0101 through 340-041-0350).

(2) Waters impounded by dams existing on January 1, 1996, which have pHs that 

exceed the criteria are not in violation of the standard, if the Department 

determines that the exceedance would not occur without the impoundment and 

that all practicable measures have been taken to bring the pH in the impounded 

waters into compliance with the criteria. 

Table 6: Summary of pH Basin Specific Criteria (OAR 340-041-0101 through 340-

041-0350

OAR Water Criteria Range

General 340-041-0021(1)(a) Marine 7.0 to 8.5

General 340-041-0021(1)(b) Estuarine and fresh waters See basin specific 

criteria

Basin or Water Body OAR Water Criteria Range

Columbia River 340-041-0104(1) Main stem Columbia River 

(mouth to river mile 309):

7.0 to 8.5

Snake River 340-041-0124(1) Main stem Snake River (river 

miles 260 to 335)

7.0 to 9.0

Deschutes Basin 340-041-0135(1)(a) All other Basin streams 

(except Cascade lakes)

6.5 to 8.5

340-041-0135(1)(b) Cascade lakes above 3,000 

feet altitude

6.0 to 8.5

Goose and Summer 

Lakes Basin

340-041-0145(1)(a) Goose Lake 7.5 to 9.5

340-041-0145(1)(b) All other basin waters 7.0 to 9.0*

Grande Ronde Basin 340-041-0156(1) All basin streams (other than 

main stem Snake River)

6.5 to 9.0*

Hood Basin 340-041-0165(1)(a) Hood River Basin streams 

(except main stem Columbia 

River and Cascade lakes)

6.5 to 8.5
May 12, 2011 Page 43

340-041-0165(1)(b) Cascade lakes above 3,000 

feet altitude

6.0 to 8.5

John Day Basin 340-041-0175(1) All Basin streams (other than 

the main stem Colombia 

River)

6.5 to 9.0*

Klamath Basin 340-041-0185(1)(a) Fresh waters except Cascade 

lakes

6.5 to 9.0*

340-041-0185(1)(b) Cascade lakes above 5,000 

feet altitude

6.0 to 8.5

Malheur Lake Basin 340-041-0195(1) 7.0 to 9.0*

Malheur River Basin 340-041-0207(1) 7.0 to 9.0*

Mid Coast Basin 340-041-0225(1)(a) Marine waters 7.0 to 8.5

340-041-0225(b) Estuarine and fresh waters 6.5 to 8.5

North Coast Basin 340-041-0235(1)(a) Marine waters 7.0 to 8.5

340-041-0235(1)(b) Estuarine and fresh waters 6.5 to 8.5

Owyhee Basin 340-041-0256(1) 7.0 to 9.0*

Powder/Burnt 

Basins

340-041-0265(1) All Basin streams (other than 

main stem Snake River)

6.5 to 9.0*

Rogue Basin 340-041-0275(1)(a) Marine waters 7.0 to 8.5

340-041-0275(1)(b) Estuarine and fresh waters 

(except Cascade lakes)

6.5 to 8.5

340-041-0275(1)(c) Cascade lakes above 3,000 

feet altitude

6.0 to 8.5

Sandy Basin 340-041-0290(1)(a) All Basin waters (except main 

stem Columbia River and 

Cascade lakes)

6.5 to 8.5

340-041-0290(1)(b) Cascade lakes above 3,000 

feet altitude

6.0 to 8.5

South Coast Basin 340-041-0305(1)(a) Estuarine and fresh waters 6.5 to 8.5

340-041-0305(1)(b) Marine waters 7.0 to 8.5

Umatilla Basin 340-041-0315(1) all Basin streams (other than 

main stem Columbia River)

6.5 to 9.0*

Umpqua Basin 340-041-0326(1)(a) Marine waters 7.0 to 8.5

340-041-0326(1)(b) Estuarine and fresh waters 

(except Cascade lakes)

6.5 to 8.5

340-041-0326(1)(c) Cascade lakes above 3,000 

feet altitude

6.0 to 8.5

Walla Walla Basin 340-041-0336 6.5 to 9.0*

Willamette Basin 340-041-0345(1)(a) All basin waters (except main 

stem Columbia River and 

Cascade lakes)

6.5 to 8.5

340-041-0345(1)(b) Cascade lakes above 3,000 

feet altitude

6.0 to 8.5.

*When greater than 25 percent of ambient measurements taken between June and September are 

greater than pH 8.7, and as resources are available according to priorities set by the Department, 

the Department will determine whether the values higher than 8.7 are anthropogenic or natural in 

origin.
May 12, 2011 Page 44

ASSIGNMENT OF ASSESSMENT CATEGORY:

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

Greater than 10 percent of the samples are outside the range of the appropriate criterion 

and a minimum of at least two samples outside the range of the appropriate criterion for 

the time period of interest.

Category 4: Water Quality Limited, TMDL Not Needed

TMDLs needed to attain applicable water quality standards have been approved

(Category 4A), other pollution control requirements are expected to address pollutant and 

will attain water quality standards (Category 4B), or impairment is not caused by a 

pollutant (Category 4C).

Category 3: Insufficient Data

Less than 5 samples for the time period of interest, or 5 to 9 samples for the time period 

of interest with 1 sample outside the range of the appropriate criterion.

Category 3B: Insufficient Data – Potential Concern

Less than 5 samples are available to evaluate for the season of interest, with 2 or more 

samples outside the range of the appropriate criterion for the time period of interest.

Category 2: Attaining

For 10 or more samples in the time period of interest, greater than 90% of the samples are 

within the range of the appropriate criterion. For 5 to 9 samples in the time period of 

interest, all samples are within the range of the appropriate criterion.

TIME PERIOD:

Summer: June 1 through September 30

Fall-Winter-Spring (FWS): October 1 to May 31

DATA REQUIREMENTS:

Data collected since 1999. A minimum of 5 representative data points available per site 

collected on separate days for each time period of interest.

NOTES:

Cascade Lakes where identified as natural and man-made lakes at elevations over 3,000

or 5,000 feet, as specified in Basin criteria.
May 12, 2011 Page 45

POLLUTANT: Sedimentation

BENEFICIAL USES AFFECTED: Resident Fish and Aquatic Life

Salmonid Fish Spawning and Rearing

NARRATIVE CRITERION: OAR 340-041-0007(12)

340-041-0007

Statewide Narrative Criteria

(12) The formation of appreciable bottom or sludge deposits or the formation of 

any organic or inorganic deposits deleterious to fish or other aquatic life or 

injurious to public health, recreation, or industry may not be allowed; 

NUMERIC CRITERION: None

WATER QUALITY LIMITED DETERMINATION (CATEGORY 5):

Previous water quality assessment methodologies (Listing Criteria for Oregon’s 1998 

303(d) List of Water Quality Limited Water Bodies) have used stream specific 

documentation that showed excessive sedimentation was a significant limitation to fish or 

other aquatic life. This included information indicating beneficial uses impairment 

(aquatic community status, biomonitoring reference sites, or fishery data) and 

measurement data for benchmarks such as cobble embeddedness or percent fines.

DEQ is currently reviewing approaches to apply a numeric benchmark based on 

measurements of stream conditions to implement the narrative criteria.

ATTAINING CRITERION DETERMINATION (CATEGORY 2):

DEQ is currently reviewing approaches to apply a numeric benchmark based on 

measurements of stream conditions to implement the narrative criteria.
May 12, 2011 Page 46

POLLUTANT: Temperature

BENEFICIAL USES AFFECTED: Salmon and Steelhead Spawning

Core Cold Water Habitat

Salmon and Trout Rearing and Migration

Salmon and Steelhead Migration Corridor

Lahontan Cutthroat Trout or Redband Trout

Bull Trout Spawning and Juvenile Rearing

NARRATIVE CRITERION: OAR 340-041-0028

NUMERIC CRITERION: OAR 340-041-0028(4)

340-041-0028

Temperature

[...]

(4) Biologically Based Numeric Criteria. Unless superseded by the natural 

conditions criteria described in section (8) of this rule, or by subsequently adopted 

site-specific criteria approved by EPA, the temperature criteria for State waters 

supporting salmonid fishes are as follows:

(a) The seven-day-average maximum temperature of a stream identified as 

having salmon and steelhead spawning use on subbasin maps and tables 

set out in OAR 340-041-0101 to 340-041-0340: Tables 101B, and 121B, 

and Figures 130B, 151B, 160B, 170B, 220B, 230B, 271B, 286B, 300B, 

310B, 320B, and 340B, may not exceed 13.0 degrees Celsius (55.4 

degrees Fahrenheit) at the times indicated on these maps and tables; 

(b) The seven-day-average maximum temperature of a stream identified as 

having core cold water habitat use on subbasin maps set out in OAR 340-

041-101 to 340-041-340: Figures 130A, 151A, 160A, 170A, 220A, 230A, 

271A, 286A, 300A, 310A, 320A, and 340A, may not exceed 16.0 degrees 

Celsius (60.8 degrees Fahrenheit);

(c) The seven-day-average maximum temperature of a stream identified as 

having salmon and trout rearing and migration use on subbasin maps set 

out at OAR 340-041-0101 to 340-041-0340: Figures 130A, 151A, 160A, 

170A, 220A, 230A, 271A, 286A, 300A, 310A, 320A, and 340A, may not 

exceed 18.0 degrees Celsius (64.4 degrees Fahrenheit);

(d) The seven-day-average maximum temperature of a stream identified as 

having a migration corridor use on subbasin maps and tables OAR 340-

041-0101 to 340-041-0340: Tables 101B, and 121B, and Figures 151A, 

170A, and 340A, may not exceed 20.0 degrees Celsius (68.0 degrees 

Fahrenheit). In addition, these water bodies must have coldwater refugia 

that's sufficiently distributed so as to allow salmon and steelhead 

migration without significant adverse effects from higher water 

temperatures elsewhere in the water body. Finally, the seasonal thermal 

pattern in Columbia and Snake Rivers must reflect the natural seasonal 

thermal pattern; 
May 12, 2011 Page 47

(e) The seven-day-average maximum temperature of a stream identified as 

having Lahontan cutthroat trout or redband trout use on subbasin maps 

and tables set out in OAR 340-041-0101 to 340-041-0340: Tables 120B, 

140B, 190B, and 250B, and Figures 180A, 201A, and 260A may not 

exceed 20.0 degrees Celsius (68.0 degrees Fahrenheit);

(f) The seven-day-average maximum temperature of a stream identified as 

having bull trout spawning and juvenile rearing use on subbasin maps set 

out at OAR 340-041-0101 to 340-041-0340: Figures 130B, 151B, 160B, 

170B, 180A, 201A, 260A, 310B, and 340B, may not exceed 12.0 degrees 

Celsius (53.6 degrees Fahrenheit). From August 15 through May 15, in 

bull trout spawning waters below Clear Creek and Mehlhorn reservoirs on 

Upper Clear Creek (Pine Subbasin), below Laurance Lake on the Middle 

Fork Hood River, and below Carmen reservoir on the Upper McKenzie 

River, there may be no more than a 0.3 degrees Celsius (0.5 Fahrenheit) 

increase between the water temperature immediately upstream of the 

reservoir and the water temperature immediately downstream of the 

spillway when the ambient seven-day-average maximum stream 

temperature is 9.0 degrees Celsius (48 degrees Fahrenheit) or greater, and 

no more than a 1.0 degree Celsius (1.8 degrees Fahrenheit) increase when 

the seven-day-average stream temperature is less than 9 degrees Celsius. 

[...]

(6) Natural Lakes. Natural lakes may not be warmed by more than 0.3 degrees 

Celsius (0.5 degrees Fahrenheit) above the natural condition unless a greater 

increase would not reasonably be expected to adversely affect fish or other 

aquatic life. Absent a discharge or human modification that would reasonably be 

expected to increase temperature, DEQ will presume that the ambient temperature 

of a natural lake is the same as its natural thermal condition.

(7) Oceans and Bays. Except for the Columbia River above river mile 7, ocean 

and bay waters may not be warmed by more than 0.3 degrees Celsius (0.5 degrees 

Fahrenheit) above the natural condition unless a greater increase would not 

reasonably be expected to adversely affect fish or other aquatic life. Absent a 

discharge or human modification that would reasonably be expected to increase 

temperature, DEQ will presume that the ambient temperature of the ocean or bay 

is the same as its natural thermal condition.

(9) Cool Water Species.

(a) No increase in temperature is allowed that would reasonably be expected to 

impair cool water species. Waters of the State that support cool water species are 

identified on subbasin tables and figures set out in OAR 340-041-0101 to 340-

041-0340; Tables 140B, 190B and 250B, and Figures 180A, 201A and 340A.

(b) See OAR 340-041-0185 for a basin specific criterion for the Klamath River.

(10) Borax Lake Chub. State waters in the Malheur Lake Basin supporting the 

Borax Lake chub may not be cooled more than 0.3 degrees Celsius (0.5 degrees 

Fahrenheit) below the natural condition.

[...]
May 12, 2011 Page 48

ASSIGNMENT OF ASSESSMENT CATEGORY:

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

Where continuous temperature data are collected, the seven-day-average maximum 

temperature exceeds the applicable criterion. Seven-day average maximum temperature 

means a calculation of the average of the daily maximum temperatures from seven 

consecutive days, made on a rolling basis.

Category 4: Water Quality Limited, TMDL Not Needed

TMDLs needed to attain applicable water quality standards have been approved

(Category 4A), other pollution control requirements are expected to address pollutant and 

will attain water quality standards (Category 4B), or impairment is not caused by a 

pollutant (Category 4C).

Category 3: Insufficient Data

Where continuous temperature data are collected, insufficient data are available to 

calculate the seven-day-average maximum temperature.

Category 2: Attaining

Where continuous temperature data are collected, the seven-day-average maximum 

temperature attains the applicable criterion.

TIME PERIOD:

In designated salmon and steelhead spawning areas, the spawning criterion will be 

applied during the time periods indicated in tables and figures referenced in OAR 340-

041-0028(4)(a). Other applicable criteria will be applied during non-spawning time 

periods.

DATA REQUIREMENTS:

Continuous temperature data collected since 2003 for the time period of interest. “Grab” 

temperature readings will not be evaluated, and “grab” data included in prior assessments 

were not re-evaluated.

Current DEQ policy is to calculate the seven-day-average maximum temperature for the 

seven days following a sampling date, and apply the criteria in effect for the first of the 

seven days.
May 12, 2011 Page 49

POLLUTANT: Total Dissolved Gas

BENEFICIAL USES AFFECTED: Resident Fish and Aquatic Life

NARRATIVE CRITERION: OAR 340-041-0031(1)

NUMERIC CRITERION: OAR 340-041-0031(2)

340-041-0031 

Total Dissolved Gas

(1) Waters will be free from dissolved gases, such as carbon dioxide hydrogen 

sulfide, or other gases, in sufficient quantities to cause objectionable odors or to 

be deleterious to fish or other aquatic life, navigation, recreation, or other 

reasonable uses made of such water. 

(2) Except when stream flow exceeds the ten-year, seven-day average flood, the 

concentration of total dissolved gas relative to atmospheric pressure at the point of 

sample collection may not exceed 110 percent of saturation. However, in 

hatchery-receiving waters and other waters of less than two feet in depth, the 

concentration of total dissolved gas relative to atmospheric pressure at the point of 

sample collection may not exceed 105 percent of saturation.

ASSIGNMENT OF ASSESSMENT CATEGORY:

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

More than 10 percent of the samples exceed standard and a minimum of at least two 

exceedences of the standard, or a survey that identifies beneficial use impairment due to 

total dissolved gas such as assessment of fish conditions.

Category 4: Water Quality Limited, TMDL Not Needed

TMDLs needed to attain applicable water quality standards have been approved

(Category 4A), other pollution control requirements are expected to address pollutant and 

will attain water quality standards (Category 4B), or impairment is not caused by a 

pollutant (Category 4C).

TIME PERIOD:

Annual
May 12, 2011 Page 50

POLLUTANT: Toxic Substances

BENEFICIAL USES AFFECTED: Aquatic Life – Fresh Water and Marine 

Water

Human Health – Water and Fish Ingestion, 

Fish Consumption, Drinking Water

NARRATIVE CRITERION: OAR 340-041-0033(1)

NUMERIC CRITERION: OAR 340-041-0033(2)

340-041-0033 

Toxic Substances 

(1) Toxic substances may not be introduced above natural background levels in

waters of the state in amounts, concentrations, or combinations that may be 

harmful, may chemically change to harmful forms in the environment, or may 

accumulate in sediments or bioaccumulate in aquatic life or wildlife to levels that 

adversely affect public health, safety, or welfare or aquatic life, wildlife, or other 

designated beneficial uses. 

(2) Levels of toxic substances in waters of the state may not exceed the applicable 

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. 

(a) Each value for criteria in Table 20 is effective until the corresponding 

value in Tables 33A or 33B becomes effective. 

(A) Each value in Table 33A is effective on February 15, 2005, 

unless EPA has disapproved the value before that date. If a value is 

subsequently disapproved, any corresponding value in Table 20 

becomes effective immediately. Values that are the same in Tables 

20 and 33A remain in effect. 

(B) Each value in Table 33B is effective upon EPA approval. 

(b) The department will note the effective date for each value in Tables 20, 

33A, and 33B as described in this section.

(3) To establish permit or other regulatory limits for toxic substances for which 

criteria are not included in Tables 20, 33A, or 33B, the department may use the 

guidance values in Table 33C, public health advisories, and other published 

scientific literature. The department may also require or conduct bio-assessment 

studies to monitor the toxicity to aquatic life of complex effluents, other suspected 

discharges, or chemical substances without numeric criteria.

Note: Oregon standards for toxic substances were revised and adopted by the 

Environmental Quality Commission in 2004 but have not yet been approved by EPA for 

Clean Water Act purposes. For the 2010 Water Quality Report, Oregon applied prerevision water quality criteria for aquatic life and human health from OAR 340-041 Table 

20 that were previously adopted and were approved by EPA in the 1980s. (See

http://www.deq.state.or.us/wq/standards/docs/toxics/Table20old.pdf for Table 20.)

Oregon standards are applicable to water column concentrations for each compound. 

Criteria for metals on Table 20 are total recoverable concentrations. DEQ recently 
May 12, 2011 Page 51

reviewed the iron and manganese Table 20 criteria and issued a policy memo discussing 

flexibility to apply the criteria to the dissolved fraction in the water column.18 The 

approach used in this assessment to evaluate iron and manganese is discussed below.

ASSIGNMENT OF ASSESSMENT CATEGORY:

For sample results reported as less than a minimum reporting limit (<MRL), the MRL 

was compared to the most stringent applicable criterion. If the MRL was higher than the 

most stringent criterion, the sample was not considered valid. If sample data needed to 

calculate toxic criteria for ammonia (temperature or pH) were not available, the sample 

was not considered valid.

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

Two (2) or more valid results not meeting the most stringent applicable criterion for 

concentrations of a specific toxic substance in the water column when these samples 

represent 5% or more of the total valid samples;

Or,

Fish consumption advisories for specific water bodies where pollutants are found in fish 

tissue. Fish consumption advisories are issued by the Oregon Department of Human 

Services Public Health Division Office of Environmental Public Health.

(See http://www.oregon.gov/DHS/ph/envtox/fishadvisories.shtml )

Category 4: Water Quality Limited, TMDL Not Needed

TMDLs needed to attain applicable water quality standards have been approved

(Category 4A), other pollution control requirements are expected to address pollutant and 

will attain water quality standards (Category 4B), or impairment is not caused by a 

pollutant (Category 4C).

Category 3B: Insufficient Data – Potential Concern

One (1) valid sample result not meeting the most stringent applicable criterion for a 

specific toxic substance when that result represents 5% or more of the total valid samples,

Or

Two (2) valid sample results not meeting the most stringent applicable criterion for a 

specific toxic substance when those results represents less than 5% of the total valid 

samples.

(See Notes below regarding alkalinity and atrazine criterion.)

Category 3: Insufficient Data

Less than 5 valid samples for the toxic substance of interest (unless assigned Category 5 

or 3B as above). For sample results reported as less than a minimum reporting limit 

(<MRL), the MRL was compared to the most stringent applicable criterion. If the MRL 

was higher than the most stringent criterion, the sample was not considered valid. If

sample data needed to calculate toxic criteria for ammonia (temperature or pH) were not 

available, the sample result was not considered valid.

 

18 Sturdevant, D., 2008, Oregon Department of Environmental Quality Memorandum Re: Iron and 

Manganese Criteria. Internal DEQ Memo Regarding Iron and Manganese Criteria - November 4, 2008 PDF
May 12, 2011 Page 52

Category 2: Attaining

A minimum of 5 valid samples and all valid results meet the most stringent applicable 

criterion for a specific toxic substance, or 

when 95% of the valid sample results meet the most stringent applicable criterion with 

only one (1) valid sample result not meeting the criterion.

Because analytical methods for some toxic substances cannot achieve reporting limits 

below the most stringent criterion (Aldrin, Arsenic, DDT, Dieldrin, PCBs, etc.), site 

monitoring data for these substances are not sufficient to determine the Attaining 

category.

TIME PERIOD:

Annual

DATA REQUIREMENTS:

Data collected since 1999.

NOTES:

Applying Aquatic Life and Human Health Criteria

To evaluate site monitoring data, the most stringent aquatic life or human health criterion

applicable to the water type was used. To select the most stringent of the applicable 

criterion, DEQ applied EPA guidance to determine when freshwater or saltwater (marine) 

aquatic life criteria for toxic substances were applicable, and additionally considered the 

human health criteria for each compound.19 A combination of salinity, conductivity, and 

geographic information for each sampling site was used to determine whether the 

freshwater or saltwater (marine) aquatic life criteria were applicable and which aquatic 

life criteria to calculate (e.g., ammonia and hardness-dependent metal criteria). The 

general approach is as described below.

Marine Waters:

Marine waters are defined in OAR 340-041-0002(34) as all oceanic, offshore water 

outside of estuaries or bays and within the territorial limits of Oregon. EPA recommends 

using saltwater criteria for waters where the salinity is equal or greater than 10 parts per 

thousand (approximately equivalent to conductivity 20,000 uS/cm).

20

Monitoring sites in marine waters were identified using geographic information and 

confirmed using salinity or conductivity data. Ammonia criteria (Acute Criteria CMC and 

 

19 2002, National Recommended Water Quality Criteria: 2002, U.S. EPA Office of Water, EPA 822-R-02-

047. Page 9.

20 Monitoring data are more commonly collected for conductivity. A general conversion is salinity 0.1 parts 

per thousand = 200 microSiemens/cm conductivity at 20°C. data are more commonly collected, and a 

general conversion is salinity . Conversion from on-line reference table at 

http://www.envcoglobal.com/files/u5/Envco%20Conductivity%20to%20salinity%20conversion%20table.p

df attributed to equation of P.K. Weyl, Liminology and Oceanography, 9:75 (1964). 
May 12, 2011 Page 53

Chronic Criterion CCC) were calculated for these sites using the appropriate equations 

for saltwater.

For marine waters, the more stringent of the marine acute or chronic criteria or the human 

health criteria for “fish-consumption-only” was applied. If there was no “fishconsumption-only” criterion, the “water and fish ingestion” criterion was applied if more 

stringent than the marine aquatic life criteria.

Estuarine Waters:

Estuarine waters are defined in OAR 340-041-0002(22) as mixed fresh and oceanic water 

in estuaries or bays from the point of inland oceanic water intrusion to a line connecting 

the outermost points of the headlands or protective jetties. EPA recommends using the 

more stringent of freshwater or saltwater criteria where salinity is between 1 and 10 

thousand parts per thousand. 

For the 2010 review of water quality data, estuarine waters were identified using 

geographic information and confirmed using salinity or conductivity data. For 

consistency with other pollutant evaluations such as bacteria, the inland extent of 

estuarine waters was identified as the point where recorded specific conductivity 

measurements were above 200 uS/cm (approximately 0.1 ppth salinity). Ammonia 

criteria (Acute Criterion CMS and Chronic Criterion CCC) for estuarine waters were 

calculated for these sites using the appropriate equations for freshwater.

For estuarine waters, the more stringent of the freshwater or marine acute or chronic 

criteria for aquatic life or the human health criterion for “fish-consumption-only” was 

applied. Estuarine waters are not considered likely drinking waters. However, if there 

was no “fish-consumption-only” criterion, the “water and fish ingestion” criterion was

applied if more stringent than the aquatic life criteria. As part of the evaluation, hardnessdependent freshwater criteria for metals were calculated for these sites.

Freshwater:

Waters that were not identified as marine or estuarine were evaluated as freshwater. For 

freshwater, the most stringent of the freshwater acute or chronic criteria or the human 

health criterion for “fish-consumption-only”, “water-and-fish-ingestion”, or “drinking 

water MCL” was applied.

Criteria Compound or Class Chemical Identification

In some cases, Table 20 toxic substance criteria compound or class names do not identify 

the specific chemicals included in the class. Analytical methods used in the past 10 years 

are able to provide detailed chemical identifications rather than results for broad 

compound classes or chemical product mixtures. In order to correctly apply Table 20 

criteria in this assessment, effort was made to correlate Table 20 criteria with chemicals 

identified by their unique CAS registry number using the 1986 guidance document used 

to develop the criteria and available chemical and CAS registry information.21, 22, 23, 24

 

21 1986, Quality Criteria for Water, U.S. EPA Office of Water, EPA 440/5-86-001
May 12, 2011 Page 54

Minimum Reporting Limit

When sample results are reported as less than a minimum reporting limit (<MRL), the 

MRL was compared to the most stringent applicable criterion. If the MRL was below the 

criterion, the result was considered a valid sample result and evaluated relative to the 

criterion. If the MRL was above the criterion, the result was not evaluated relative to the 

criterion.

TOXIC CRITERIA ISSUES:

Alkalinity Criterion

The freshwater criterion for alkalinity is “20 mg/L or more as CaCO3 freshwater aquatic 

life except where natural concentrations are less.”25 Alkalinity should not be below this 

value in order to protect beneficial uses.

Alkalinity is a measure of carbonate and bicarbonate ions and the buffering capacity of 

water to pH changes. Freshwater systems have natural variations in pH that are related to 

photosynthetic activity and other inorganic and organic chemical reactions. Applying the 

alkalinity criterion as an isolated standard to determine where water is water quality 

limited may lead to incorrect conclusions about overall natural water quality. For the 

2010 Integrated Report evaluation, analytical data indicating alkalinity less than the 

criterion is flagged as a Category 3B Insufficient Data – Potential Concern.

Professional judgment should be used during TMDL development or on a case-by-case 

basis to consider alkalinity information along with information for other related pollutant 

pollutants such as pH, chlorophyll a, aquatic weeds or algae growth, and dissolved 

oxygen when addressing beneficial use support.

Ammonia Criteria

Ammonia criteria are established based on the concentration of un-ionized ammonia 

(NH3) which is the principal toxic form of ammonia, and are pH and temperature 

specific.

26 Monitoring data results are typically reported as “total ammonia as N”. For the 

assessment evaluation, criteria are calculated for freshwater and saltwater first for unionized ammonia (NH3), and then converted to criteria for total ammonia as N in order to 

evaluate monitoring data results. If temperature or pH data were not available, criteria 

were not calculated and the sample result was not evaluated.

Ammonia Criteria - Freshwater

Ammonia criteria for freshwater are calculated based on pH, temperature, and the 

presence or absence of salmonids or other fish with ammonia-sensitive life stages. For 

this assessment, salmonids were always assumed to be present. Values for freshwater 

 

22 National Institute of Standards and Technology web site “Search for Species Data by CAS Registry” at 

http://webbook.nist.gov/chemistry/cas-ser.html

23 Agency for Toxic Substance and Disease Registry web site at http://www.atsdr.cdc.gov/

24 US EPA Substance Registry Services web site “Substance Search” at 

http://iaspub.epa.gov/sor_internet/registry/substreg/searchandretrieve/substancesearch/search.do

25 1986, Quality Criteria for Water, U.S. EPA Office of Water, EPA 440/5-86-001

26 1986, Quality Criteria for Water 1986, U.S. EPA Office of Water, EPA 440/5-86-001
May 12, 2011 Page 55

criteria for un-ionized ammonia (NH3) are calculated first, then converted to criteria for 

total ammonia as N using the following formulae.

27, 28 EPA recommends criteria 

calculations not be extrapolated beyond the pH and temperature limits specified in the 

formulae.26, 27

Freshwater Acute Criterion (CMC = Criterion Maximum Concentration):

Salmonids present:

CMC NH3 = 0.52 / FT / FPH / 2

Where:

FT = 1 when 20  Temperature (T)  30 

Or

FT = 10 0.03(20-T) when 0  T < 20

And:

FPH = 1 when 8  pH  9

Or

FPH = 1 + 10 7.4-pH when 6.5  pH < 8

 1.25

Salmonids absent:

CMC NH3 = 0.52 / FT / FPH / 2

Where:

FT = 0.71 when 25  T  30 

Or

FT = 10 0.03(20-T) when 0  T < 25

And:

FPH = 1 when 8  pH  9

Or

FPH = 1 + 10 7.4-pH when 6.5  pH < 8

 1.25

Freshwater Chronic Criterion (CCC = Criterion Continuous Concentration):

Salmonids present:

CCC NH3 = 0.80 / FT / FPH / RATIO

Where:

FT = 1.4 when 15  T  30 

Or

FT = 10 0.03(20-T) when 0  T < 15

 

27 1985, Ambient Water Quality Criteria for Ammonia - 1984, U.S. EPA Office of Water, EPA 440/5-85-

001

28 1986, Quality Criteria for Water 1986, U.S. EPA Office of Water, EPA 440/5-86-001
May 12, 2011 Page 56

And:

FPH = 1 when 8  pH  9

Or

FPH = 1 + 10 7.4-pH when 6.5  pH < 8

 1.25

And:

RATIO = 16 when 7.7 pH  9

Or

RATIO = 24*(10 7.7-pH/1+10 7.4-pH) when 6.5 pH <7.7

Salmonids absent:

CCC NH3 = 0.80 / FT / FPH / RATIO

Where:

FT = 1 when 20  T  30 

Or

FT = 10 0.03(20-T) when 0  T <20

And:

FPH = 1 when 8  pH  9

Or

FPH = 1 + 10 7.4-pH when 6.5  pH < 8

 1.25

And:

RATIO = 16 when 7.7 pH  9

Or

RATIO = 24*(10 7.7-pH/1+10 7.4-pH) when 6.5 pH <7.7

Ammonia criteria calculated above are for the un-ionized ammonia (NH3) fraction.29

Criteria for total ammonia as N are calculated using the following equations:30

pKa = 0.09018 + (2729.92/(273.15 + Temperature))

Fraction = 1/(10^(pKa – pH) + 1)

CMC(Total ammonia as N) = CMCNH3 /Fraction*0.822

CCC(Total ammonia as N) = CCCNH3 /Fraction*0.822

Ammonia Criteria – Saltwater

Ammonia criteria for saltwater are established for un-ionized ammonia (NH3) which is 

the principal toxic form of ammonia.31 For this assessment, the saltwater criteria were 

 

29 1985, Ambient Water Quality Criteria for Ammonia - 1984, U.S. EPA Office of Water, EPA 440/5-85-

001. http://www.epa.gov/waterscience/criteria/library/ambientwqc/ammonia1984.pdf

30 1999, 1999 Update of Ambient Water Quality Criteria for Ammonia, U.S. EPA Office of Water, EPA 

822-R-99-014. http://www.epa.gov/waterscience/criteria/ammonia/99update.pdf

31 1989, Ambient Water Quality Criteria for Ammonia (Saltwater)-1989, U.S. EPA Office of Water, EPA 

440/5-88-004; http://www.epa.gov/ost/pc/ambientwqc/ammoniasalt1989.pdf
May 12, 2011 Page 57

calculated criteria for marine sites. Marine sites were identified using geographic 

information and confirmed with salinity or conductivity data. A default salinity value of 

10 ppth was used if site specific data were not available. 

Saltwater Acute Criterion (CMCS= Criterion Maximum Concentration):

CMCS

NH3 = 0.233 mg/L 

Saltwater Chronic Criterion (CCCS= Criterion Continuous Concentration):

CCC S

NH3 = 0.035 mg/L 

EPA provides a model to approximate the percent un-ionized ammonia in saltwater using 

the equations below, and to calculate the criteria in terms of total ammonia as N. 

% Unionized Ammonia (UIA) =100*[1+10^ (pKaS +0.0324*(298-T) +0.0415*P/T-pH)]-1

Where:

S = salinity (g/kg)

T = temperature (oK) 

P = 1 atm pressure (default)

And:

pKa

S

= 9.245+0.116*MIS

MIS = Molal Ionic Strength of seawater = (19.9273*S)/ (1000-1.005109*S)

To calculate the criteria in terms of total ammonia as N:

Saltwater Acute Criterion (CMC = Criterion Maximum Concentration):

CMCS

(Total ammonia as N) = CMCSNH3 /UIA*0.822= 0.233/UIA*0.822

Saltwater Chronic Criterion (CCC = Criterion Continuous Concentration):

CCC

S

(Total ammonia as N) = CCC

S

NH3 /UIA*0.822= 0.0.035/UIA*0.822

Atrazine MCL

Oregon does not have water quality criteria for atrazine. However, since the adoption and 

approval of Table 20 water quality criteria, National Primary Drinking Water regulations 

have promulgated a Maximum Contaminant Level (MCL) of 3 ug/L for drinking water. 

For the 2010 Integrated Report evaluation, analytical data exceeding this MCL is flagged 

as Category 3B: Insufficient Data – Potential Concern.

Chlordane and Heptachlor Criteria

Table 20 criteria for Chlordane were applied to sample results reported for the technical 

product (CAS No. 12789036) or non-specific chlordane (CAS No. 57749), or to the sum 

of isomers, other constituents, and metabolites of chlordane including cis-chlordane 

(synonym α-chlordane) (CAS No. 5103719), trans-chlordane (synonym γ- chlordane)

(CAS No. 5103742), γ-chlordane (CAS No. 5566347), cis-nonachlor (CAS No. 

 
May 12, 2011 Page 58

5103731), trans-nonachlor (CAS No. 39765805), and oxychlordane (CAS No. 

27304138). 

Another known major constituent of chlordane mixtures is Heptachlor (CAS No. 76448). 

Table 20 criteria specific for Heptachlor were applied separately for this chemical.

Chromium Criteria

Table 20 criteria for chromium have criteria for two oxidation states – hexavalent and 

trivalent. However, analytical results for chromium do not distinguish between oxidation 

states. The most stringent applicable aquatic or human health value for either oxidation 

state was applied to evaluate data results.

DDT Criteria

Table 20 criteria for DDT were applied to sample results reported for 4,4 DDT or p,p 

DDT (CAS No. 50293). These criteria are not applicable to results reported for DDD 

(CAS No. 72548); DDE (CAS No. 72559); 2,4 DDT (CAS No. 789026); 2,4 DDD (CAS 

No. 53190); or 2,4 DDE (CAS No. 3424826) which do not have criteria on Table 20 and 

were not evaluated.

Demeton Criteria

Table 20 criteria for Demeton were applied to sample results reported as Demeton (CAS 

No. 8065483), and Disulfoton (CAS No. 298044). The two pesticides are toxicologically 

similar, and EPA allows use of toxicity data for both compounds. For this assessment, the 

Demeton criteria were applied to both pesticide products.

Dichlorobenzenes Criteria

Table 20 criteria for the class Dichlorobenzenes were applied to the sum of sample results 

reported for the isomers 1,2-Dichlorobenzene (CAS No. 95501); 1,3-Dichlorobenzene

(CAS No. 541731); and 1,4-Dichlorobenzene (CAS No. 106467).

Dichloroethylenes Criteria

Table 20 criteria for the class Dichloroethylenes were applied to the results reported for 

1,1-Dichloroethylene (synonyms 1,1-Dichloroethene or 1,1-DCE) (CAS No. 75354).

Dichloropropene Criteria

Table 20 criteria for the compound Dichloropropene were applied to the sum of sample 

results reported for the isomers cis-1,3-Dichloropropene (CAS No. 10061015); trans-1,3-

Dichloropropene (CAS No. 10061026); mixtures of cis- and trans-1,3-Dichloropropene 

(CAS No. 542756); 1,1-Dichloropropene (CAS No. 563586); and 1,2-Dichloropropene 

(CAS No. 563542).

Dioxin (2,3,7,8-TCDD) Criteria

Table 20 criteria for Dioxin were applied to sample results reported for the specific 

congener 2,3,7,8-Tetrachlorodibenzodioxin (TCDD) (CAS No. 1746016).
May 12, 2011 Page 59

Diphenylhydrazine Criteria

Table 20 criteria for Diphenylhydrazine were applied to results for Diphenylhydrazine 

1,2- (synonym Hydrazobenzene) (CAS No. 122667). No data results for this chemical 

were available for the 2010 evaluation.

Endosulfan Criteria

Table 20 criteria for the group Endosulfan were applied to sample results reported for 

Endosulfan (CAS No. 115297) or to the sum of sample results reported for the isomers αEndosulfan (CAS No. 959988), β-Endosulfan (33213659), and the reaction product 

Endosulfan sulfate (CAS No. 1031078) found in technical grade Endosulfan.

Guthion Criteria

Table 20 criteria for Guthion were applied to results for Guthion (synonym Azinphos 

Methyl) (CAS No. 86500) and for the metabolic breakdown product Azinphos Methyl 

Oxygen Analog (CAS No. 961228).

Halomethanes Criteria

Table 20 criteria for the group Halomethanes were applied to the sum of sample results 

reported for the following compounds if available:

Bromodichloromethane (CAS No. 75274)

Bromoform (synonym Tribromomethane) (CAS No. 75252)

Bromomethane (CAS No. 74839)

Chloromethane (CAS No. 74873)

Dichlorodifluoromethane (CAS No. 75718)

Methylene Chloride (synonym Dichloromethane) (CAS No. 75092)

Trichlorofluoromethane (CAS No. 75694)

Hexachlorocyclohexane Criteria

Table 20 criteria aquatic life criteria for Hexachlorocyclohexane (Lindane) and human 

health criteria for Hexachlorocyclohexane Gamma were applied to sample results 

reported for chemical (CAS No. 58899). The pesticide product Lindane is generally > 

99% the gamma isomer (synonyms γ-HCH or γ-BHC).

Table 20 criteria human health criteria for the isomer Hexachlorocyclohexane alpha were 

applied to results for that chemical (CAS No. 319846) (synonyms α-HCH or α-BHC).

Table 20 criteria human health criteria for the isomer Hexachlorocyclohexane beta were 

applied to results for that chemical (CAS No. 319857) (synonyms β-HCH or β-BHC).

Table 20 criteria human health criteria for the Hexachlorocyclohexane technical apply to 

the technical grade pesticide which is a mixture consisting of α, β, γ, δ, and ε isomers. No 

data results for the technical mixture were available for the 2010 evaluation.

Metals Criteria - Evaluation of Total Recoverable Results

Table 20 criteria for metals are established for total metal concentrations in water. To 

evaluate water quality for metals, results for total recoverable analyses were compared to 
May 12, 2011 Page 60

the applicable criteria. If no total analysis was available, then a dissolved analytical result 

was evaluated against the criteria. If the data do not identify the analysis as total or 

dissolved, the result was evaluated as if it were a total analysis.

For iron and manganese, a recent DEQ review of the criteria resulted in a policy memo 

discussing DEQ’s flexibility to apply the criteria for these compounds to the dissolved 

fraction in the water column.32 To evaluate iron and manganese, results for dissolved 

analyses were compared to the applicable criteria. If no dissolved analysis was available, 

then data were not evaluated against the criteria.

Metals Criteria - Hardness Dependent Criteria

The freshwater criteria for several metals are expressed as a function of hardness (mg/L) 

in the water column. These criteria are flagged on Table 20 with a “+” notation. Criteria 

for these metals are calculated using the following formulae:

33

Freshwater Acute Criterion: Criterion maximum concentration 

CMC = e 

(ma [ln(hardness)]+ ba)

Freshwater Chronic Criterion: Criterion chronic concentration

CCC = e

(mc [ln(hardness)]+ bc)

Metal Freshwater Acute Criterion

CMC

Freshwater Chronic Criterion

CCC

ma ba mc bc

Cadmium 1.128 -3.828 0.7852 -3.490

Chromium 0.819 3.688 0.819 1.561

Copper 0.9422 -1.464 0.8545 -1.465

Lead 1.273 -1.460 1.273 -4.705

Nickel 0.8460 3.3612 0.8460 1.1645

Silver 1.72 -6.520

Zinc 0.8473 0.8604 0.8473 0.7614

If hardness was not measured directly as CaCo3, the following equation was used to 

calculate the hardness value34:

Hardness, equivalent CaCo3 (mg/L) = 2.497 Ca (mg/L) + 4.1189 Mg (mg/L)

For this assessment, DEQ followed EPA recommendations to use a minimum of 25 mg/L

hardness to calculate criteria.35 Additionally, if no hardness data were available, a default 

hardness of 25 mg/L was use to calculate the criteria.

 

32 Sturdevant, D., 2008, Oregon Department of Environmental Quality Memorandum Re: Iron and 

Manganese Criteria. Internal DEQ Memo Regarding Iron and Manganese Criteria - November 4, 2008 PDF

33 1986, Quality Criteria for Water, U.S. EPA Office of Water, EPA 440/5-86-001

34 1998, Standard Methods for the Examination of Water and Wastewater, 20th edition, American Public 

Health Association, American Water Works Association, Water Environment Federation

35 40 CFR Section 131.36(c)(4)(i).
May 12, 2011 Page 61

Nitrosamines Criteria

Table 20 contains criteria for the Nitrosamine class of compounds. However, Table 20 

also has specific criteria for the individual chemicals which are applied to data results for:

Nitrosodibutylamine n- (CAS No. 924163)

Nitrosodiethylamine n- (CAS No. 55185)

Nitrosodimethylamine n- (CAS No. 62759)

Nitrosodiphenylamine n- (CAS No. 86306)

Nitrosopyrrolidine n- (CAS No. 930552)

Parathion Criteria

Table 20 criteria for Parathion were applied to results for Parathion both Ethyl Parathion

(CAS No. 56382) and Methyl Parathion (CAS No. 298000). Both pesticides were 

registered and in use when Table 20 criteria were established.

PCB Criteria

Table 20 criteria for PCBs (Polychlorinated Biphenyls) were applied to either the sum of 

sample results reported as Aroclors, or the sum of sample results reported as congeners. 

Available data for 2010 included results for Aroclors 1016, 1221, 1232, 1242, 1248, 

1254, and 1260. Available data for 2010 included results for congeners PCB-1, PCB-5, 

PCB-29, PCB-47, PCB-98, PCB-154, PCB-171, and PCB-200.

Pentachlorophenol Criteria

Freshwater aquatic life criteria for Pentachlorophenol (CAS No. 87865) are pH 

dependent and can be calculated by:36

Acute Criterion (CMC = Criterion Maximum Concentration)

CMC = e 

(1.005(pH)-4.830)

Chronic Criterion (CCC = Criterion Continuous Concentration):

CCC = e 

(1.005(pH)-5.290)

A simplifying assumption is to use a pH of 7.8 to generate the criteria as given on Table 

20. For this assessment to evaluate Pentachlorophenol (CAS No. 87865), pH criteria were 

calculated using the 1986 guidance for calculating national criteria. If no pH data were 

available, the Table 20 assumptions of pH 7.8 were used to generate criteria.

Phosphorus Criterion/Phosphate Phosphorus Benchmark

The Table 20 criterion of 0.1 ug/L applies to elemental phosphorus (P) in marine or 

estuarine waters. This is based on the EPA criterion to protect marine organisms.37

Neither Oregon nor EPA has set a criterion for phosphate phosphorus. EPA has 

recognized the relationship between phosphates, as major nutrients, and excessive aquatic 

weed and algae growth, and lake and reservoir eutrophication.38 EPA recommends that 

 

36 1986, Ambient Water Quality Criteria for Pentachlorophenol, U.S. EPA Office of Water, EPA 440/5-86-

009.

37 1986, Quality Criteria for Water, U.S. EPA Office of Water, EPA 440/5-86-001 for Phosphorus 

38 1986, Quality Criteria for Water, U.S. EPA Office of Water, EPA 440/5-86-001 for Phosphate 

Phosphorus
May 12, 2011 Page 62

total phosphates as phosphorus (P) should not exceed 50 ug/L in streams to control 

excessive aquatic growths. For the 2010 Water Quality Report, this value is used as a 

benchmark to evaluate water quality data for phosphate phosphorus. Water bodies with 

total phosphates as phosphorus (P) greater than 50 ug/L are a Category 3B Insufficient 

Data – Potential Concern for conditions that may result in not meeting water quality 

standards.

Polynuclear Aromatic Hydrocarbons Criteria

Table 20 criteria for the group Polynuclear Aromatic Hydrocarbons (PAHs) were applied 

to sum of sample results reported for the following compounds if available:

Acenaphthene (CAS 83329)

Acenaphthylene (CAS 208968)

Anthracene (CAS 120127)

Benz[a]anthracene (CAS 56553)

Benzo[a]pyrene (CAS 50328)

Benzo[b]fluoranthene (CAS 205992)

Benzo[e]pyrene (CAS 192972)

Benzo[g,h,i]perylene (CAS 191242)

Benzo[k]fluoranthene (CAS 207089)

Benzo[j]fluoranthene (CAS 205823)

Chrysene (CAS 218019)

Dibenz[a,h]anthracene (CAS 53703)

Fluorene (CAS 86737)

Indeno[1,2,3-c,d]pyrene (CAS 193395)

Phenanthrene (CAS 85018)

Pyrene (CAS 1290000)

Table 20 criteria for Fluoranthene (CAS 206440) were applied to results reported for that 

one PAH compound.
May 12, 2011 Page 63

POLLUTANT: Turbidity

BENEFICIAL USES AFFECTED: Resident Fish and Aquatic Life

Water Supply

Aesthetics

NARRATIVE CRITERION: OAR 340-041-0007 (11)

340-041-0007

Statewide Narrative Criteria

(11) The creation of tastes or odors or toxic or other conditions that are 

deleterious to fish or other aquatic life or affect the potability of drinking water or 

the palatability of fish or shellfish may not be allowed;

NUMERIC CRITERION: OAR 340-041-0036

340-041-0036

Turbidity

Turbidity (Nephelometric Turbidity Units, NTU): No more than a ten percent 

cumulative increase in natural stream turbidities may be allowed, as measured 

relative to a control point immediately upstream of the turbidity causing activity. 

However, limited duration activities necessary to address an emergency or to 

accommodate essential dredging, construction or other legitimate activities and 

which cause the standard to be exceeded may be authorized provided all 

practicable turbidity control techniques have been applied and one of the 

following has been granted: 

(a) Emergency activities: Approval coordinated by the Department with 

the Oregon Department of Fish and Wildlife under conditions they may 

prescribe to accommodate response to emergencies or to protect public 

health and welfare;

(b) Dredging, Construction or other Legitimate Activities: Permit or 

certification authorized under terms of section 401 or 404 (Permits and 

Licenses, Federal Water Pollution Control Act) or OAR 14l-085-0100 et 

seq. (Removal and Fill Permits, Division of State Lands), with limitations 

and conditions governing the activity set forth in the permit or certificate.

ASSIGNMENT OF ASSESSMENT CATEGORY:

Category 5: Water Quality Limited, TMDL Needed (303(d) List)

A systematic or persistent increase (of greater than 10%) in turbidity due to an 

operational activity that occurs on a persistent basis (e.g. dam release or irrigation return, 

etc.);

Or,

For impairments to beneficial use as drinking water supply, Public Water System 

operator indicates that high turbidity days (days with turbidity ≥5 NTU) are causing 

operational difficulty and source water data validate this impairment. The data are 

considered to validate an impairment if more than 45 high turbidity days per year occur 

for any year for which data are available.
May 12, 2011 Page 64

Category 3: Insufficient Data

For beneficial use as drinking water supply, available data are not sufficient to determine 

if the use is impaired. One or more turbidity shutdowns are documented in the Safe 

Drinking Water Information System database, but there are not data to show whether 

shutdown is normal after a large storm event, or indicates a problem and impaired 

beneficial use.

Category 3b: Potential Concern, Insufficient Data

For beneficial use as drinking water supply, available data are not sufficient to determine 

if the use is impaired, but indicate a potential concern. The Public Water System operator 

indicates that high turbidity days are causing operational difficulties, but there are not 

data available to validate this impairment, or if shutdowns due to high turbidity may be 

the result of unusual or infrequent weather events.

Category 2: Attaining

For beneficial use as drinking water supply, Public Water System operator indicates that 

high turbidity days are not causing operational difficulty and/or source water data show 

water quality is good. Water quality is considered good if there are 45 or less high 

turbidity days per year for all years for which data are available.
May 12, 2011 1 Appendix 1

Appendix 1

Rules for Defining Water Body Segments and Assigning 

Assessment Status Category

Rules for 2004 for

Temperature and Dissolved Oxygen

Use segments designated in Oregon Administrative Rules (OAR) Chapter 340 Division 

41 as revised in 2003 for designated fish beneficial uses and designated spawning time 

periods. Assign status as follows:

If Then:

2004 stations 2004 Segment 2004 Status

One or more station 

303d

Start and end river 

mile for designated 

fish use

Cat 5: 303d list

One or more 

stations 303d

TMDL approved 

for temperature or 

dissolved oxygen 

for stream

Start and end river 

mile for designated 

fish use

Cat 4a: WQ 

limited, TMDL 

approved

One or more 

stations 303d, 

others insufficient 

data

Start and end river 

mile for designated 

fish use

Cat 5: 303d list

One or more 

stations attaining; 

others insufficient 

data

Start and end river 

mile for designated 

fish use

Cat 2: Attaining

One or more 

stations with 

insufficient data

Start and end river 

mile for designated

fish use

Cat 3: Insufficient 

data

No data 2002 303d status Retain previous 

segment start and 

end

303d based on 

previous listing
May 12, 2011 2 Appendix 1

Other Pollutants

For pollutants other than temperature and dissolved oxygen, if segment was defined in 

2004 for pollutant and season, use pre-existing segment river mile start and end.

For bacteria, use 2004 segment for matching pollutant and season (example, e.coli for 

summer):

If match for pollutant but not season, use segment for matching pollutant for any 

season (example, e.coli for fall/winter/spring). Assign 2010 status based on 

evaluation of 2010 data.

If no match for pollutant, use segment for other bacteria pollutant (example, for e. 

coli, use previous fecal coliform segment). Assign 2010 status based on 

evaluation of 2010 data.

For segments with matching pollutant and season, assign status to segment as follows:

If And Then:

2010 stations 2004 Segment 

Status

2010Segment 2010 Status

One or more stations 303d 303d Same Cat 5: 303d list

One or more stations 303d TMDL approved Same Cat 4a: WQ limited, 

TMDL approved

One or more stations 303d Attaining Same Cat 5: 303d list

Stations insufficient data 303d Same Cat 5: 303d list

One or more stations 

potential concern (toxics)

303d Same Cat 5: 303d list

One or more stations 

potential concern (toxics)

Potential concern 

or insufficient data

Same Cat 3B: Insufficient 

Data – Potential 

Concern

One or more stations 

potential concern (toxics)

Attaining Same Cat 3B: Insufficient 

Data – Potential 

Concern

Stations insufficient data Attaining Same Cat 2: Attaining

Stations insufficient data Potential concern Same Cat 3B: Insufficient 

Data – Potential 

Concern

One or more stations 

attaining and one or more 

stations insufficient data

Attaining Same Cat 2: Attaining

Attaining and/or 

insufficient data

303d Same Cat 5: 303d list

(Check for data 

equivalency to de-list).

Combination insufficient 

data, 303d, and attaining

303d Same Cat 5: 303d list

Stations attaining Attaining Same Cat 2: Attaining

Combination insufficient 

data, 303d, and attaining

Attaining Same Cat 5: 303d list

Attaining TMDL approved Same Cat 2: Attaining
May 12, 2011 3 Appendix 1

Other Pollutants (con’t)

If NO segment is defined in 2004 for pollutant and season, define 2010 segment up to the 

next monitoring station and assign 2010 status to segment as follows:

If And No 

2004

Segment

Then:

2010 stations 2010 segment 2010 segment status

One station 303d Mouth to headwaters Cat 5: 303d list

One or more 

stations 303d 

with upstream 

data points.

Segment from mouth 

up to next station that 

shows other status 

information

Cat 5: 303d list

One station 303d 

with downstream 

station attaining

Define segments 

start/end at halfway 

point between 

attaining and 303d 

point

Cat 2: Attaining from data 

point to halfway ;

Cat 5 303d list from halfway 

below data point to next 

upstream data point showing 

different status.

One or more 

station 303d, 

other insufficient 

data

Mouth to headwaters Cat 5: 303d list

One or more 

station attaining; 

others with 

insufficient data

Mouth to headwaters Cat 2: Attaining

One or more 

stations with 

insufficient data

Mouth to headwaters Cat 3: Insufficient data
Appendix 2

Appendix 2

June 22, 1998

Philip Millam

Director, Office of Water, OW-134

U.S. Environmental Protection Agency, Region X

1200 Sixth Avenue

Seattle, Washington 98101

Dear Phil:

This letter is to provide policy clarification of the Oregon water quality standards revisions 

that were submitted for Environmental Protection Agency’s (EPA) approval on July 10, 

1996. Specifically, this letter addresses how the Department of Environmental Quality 

(ODEQ ) is interpreting certain language contained in the Oregon Water Quality Standards 

(OAR 340-41) and responds to questions that EPA has raised in its review of the standards.

The regulatory clarifications included herein will be incorporated into the water quality 

standards, to the extent possible, during the next triennial review. As there are quite a 

number of issues that are candidates for review in the next triennial review, we will need to 

carefully prioritize these issues working with EPA and the next Policy Advisory Committee.

The following comments are organized in the following manner: beneficial use issues, 

numeric criteria issues and implementation issues.

BENEFICIAL USE ISSUES:

Bull Trout Waters: The language in the rule (OAR 340-41- basin (2)(b)(A)) reads: “...no 

measurable surface water temperature increase resulting from anthropogenic activities is 

allowed: ... (v) In waters determined by the Department to support or to be necessary to 

maintain the viability of native Oregon bull trout, when surface water temperatures exceed 

50.0o F (12.8o C)”. [Please note that the specific citation for the temperature criteria for Bull 

Trout may vary slightly in its numbering depending on the basin, this example and 

subsequent citations are from the standards for the Willamette Basin (OAR 340-41-445)].

The Department has consulted with the Oregon Department of Fish and Wildlife (ODFW) to 

make a determination of the current distribution of Bull Trout. Maps have been developed 

by ODFW as part of an effort to develop plans to protect and restore Bull Trout populations.

These maps can be found in the following publication: “Status of Oregon’s Bull Trout”

(Oregon Department of Fish and Wildlife; October 1997; Buchanan, David, M. Hanson, and 

R. Hooton; Portland, OR) which is available from ODFW or viewed in the “StreamNet” 

website (www.streamnet.org). A map showing the most recent Bull Trout distribution (export 

file dated June 1997) has been sent separately to EPA and a digital version can be 

provided to EPA.
Page 2 Appendix 2

The Department will use the 1997 Bull Trout distribution maps contained in the 1997 ODFW 

publication to clarify the phrase “waters determined by the Department to support or to be 

necessary to maintain the viability of native Oregon Bull Trout.” The temperature criteria of 

50oF applies to the stream reaches which indicate that “Spawning, Rearing, or Resident 

Adult Bull Trout” populations are present. These waters are shown by a solid green line on 

the maps that are referenced.

The mapping and planning effort is an on-going effort by ODFW. Any changes made to the 

mapped distribution will represent a change in the standard which would be submitted to 

EPA for approval. The Bull Trout portion of the standards will be revised to incorporate a 

reference to the 1997 ODFW publication or identify any other means for determining waters 

that support or are necessary to support Bull Trout in the next triennial standards review.

Waters supporting spawning, egg incubation and fry emergence: The language in the 

rule reads: 

Temperature (OAR 340-41- basin (2)(b)(A)): “...no measurable surface water temperature 

increase resulting from anthropogenic activities is allowed: ... (iv) In waters and periods of 

the year determined by the Department to support native salmonid spawning, egg 

incubation, and fry emergence from the egg and from the gravels in a basin which exceeds 

55oF (12.8oC)”.

Dissolved Oxygen (OAR 340-41- basin (2)(a)(A)): “For waterbodies identified by the 

Department as providing salmonid spawning, during the periods from spawning until fry 

emergence from the gravels, following criteria apply...”

The Beneficial Use Tables (Tables 1-19 in the Oregon water quality standards) indicate the 

recognized beneficial uses to generally be protected in the basin. In some basins (e.g. 

Table 15, Malheur River Basin), the information in the Tables has been refined for particular 

water bodies. In general, salmonid spawning and rearing are shown on the tables to be 

found in all basins. In order to make the spawning determinations, information on location 

and timing in a specific waterbody is further developed through consultation with ODFW as 

spawning does not occur at all times of the year or in all locations in the basin. In addition, 

timing often varies from year to year depending on seasonal factors such as flow. ODFW, in 

cooperation with other federal and tribal fishery agencies has begun to map out this 

information on a species by species basis (StreamNet Project) but this work is still several 

years from completion.

ODEQ is submitting the attached table that identifies when the spawning criteria listed 

under the dissolved oxygen and temperature standards will be applied to a basin. This table 

provides the generally accepted time frame during which spawning occurs. However,

spawning periods for Spring Chinook and Winter Steelhead vary with elevation (e.g. Spring 

Chinook tend to spawn earlier and fry emergence occurs later in the Spring for Winter 

Steelhead in streams at higher elevations). Therefore, to address differences in actual 

spawning periods, the Department will consult directly with the ODFW to determine if 

waterbody specific adjustments (which would be changes to the standards) are necessary.

Furthermore, the Department will apply the antidegradation policy in specific actions, e.g. 

permits, 401 certification and 303(d) listing, to protect spawning that occurs outside the 
Page 3 Appendix 2

identified time frames or utilize the narrative temperature criteria that applies to threatened 

or endangered species. 

Application of the warm-water Dissolved Oxygen Criteria (OAR 340-41- basin 

(2)(a)(F)): The language in the rule reads: “For waterbodies identified by the Department as 

providing warm-water aquatic life, the dissolved oxygen shall not be less than 5.5 mg/l as 

an absolute minimum...”

Warm-water criteria is applied in waters where Salmonid Fish Rearing and Salmonid Fish 

Spawning are not a listed beneficial use in Tables 1 - 19 with the exception of Table 19 

(Klamath Basin) in which the cool water dissolved oxygen criteria will be applied (see 

Klamath TMDL supporting documentation, (Hammon 1998)). Specifically, the warm water 

criteria would be applied to:

Table 15: Malheur River (Namorf to Mouth), Willow Creek (Brogan to Mouth), Bully 

Creek (Reservoir to Mouth); 

Table 16: Owyhee River (RM 0-18);

Table 17: Malheur Lake Basin - Natural Lakes;

Table 18: Goose and Summer Lakes Basin - High Alkaline & Saline Lakes.

Application of the cool-water Dissolved Oxygen Criteria (OAR 340-41- basin (2)(a)(E)):

The language in the rule reads: “For waterbodies identified by the Department as providing 

cool-water aquatic life, the dissolved oxygen shall not be less than 6.5 mg/l as an absolute 

minimum...”

Cool-water aquatic life is a sub-category of cold-water aquatic life and is defined under 

OAR 340-41-006 (52) as “the aquatic communities that are physiologically restricted to cool 

waters, composed of one or more species having dissolved oxygen requirements believed 

similar to the cold-water communities. Including but not limited to Cottidae, Osmeridae, 

Acipenseridae, and sensitive Centrachidae such as the small-mouth bass.” This criteria will 

be applied on an ecoregional basis39 (see attached map) as follows:

West Side:

Cold Water: Coast Range Ecoregion - all, Sierra Nevada Ecoregion -all, Cascade-all, 

Willamette Valley - generally typical including Willamette River above Corvallis, Santiam 

(including the North and South), Clackamas, McKenzie, Mid Fork and Coast Fork 

mainstems.

 

39 The original Ecoregions described in “Ecorgions of the Pacific Northwest” (James Omernik and A. Gallant, 1986, 

EPA/600/3-86/033) were used. This work is currently being updated but is not complete for Oregon. The terms most typical 

and generally typical are defined as follows: “The most typical portions of ecoregions are generally those areas that share all

of the characteristics that are predominant in each ecoregion. The remaining portions, generally typical of each ecoregion, 

share most, but not all, of these same characteristics. These areas are defined on maps included in the publication referenced 

above and have been sent separately to EPA. 
Page 4 Appendix 2

Cool Water: Willamette Valley Ecoregion - most typical.

East Side (with the exception of waters listed under warm water criteria in Tables 15-19):

Cold Water: Eastern Cascades Slopes and Foothills - most typical, Blue Mountain -

most typical.

Cool Water: Remainder of Eastern Oregon Ecoregions.

NUMERIC CRITERIA ISSUES:

Temperature criteria for waters without a specific numeric criterion: The temperature 

criteria of 64oF will be applied to all water bodies that support salmonid fish rearing as 

identified in Tables 1 - 19. This would include all waters except those listed as warm water 

above. Currently, there is no numeric criteria for those waters listed as warm water. This 

was an inadvertent oversight for the rivers described under 2 and 3 below which will be 

corrected by setting site specific criteria during the next triennial review. In the mean time, 

these waters will be protected as follows: 

1. There is a criteria that covers natural lakes and would cover lakes in the Malheur Lake 

Basin (Table 17) and Goose and Summer Lakes Basin (Table 18). This criteria (OAR 

340-41-922 (2)(b)(A)) reads: “...no measurable surface water temperature increase

resulting from anthropogenic activities is allowed: ... (vii) In natural lakes”.

2. The waters shown in the Klamath Basin (Table 19) are currently listed in Oregon’s 

1994/96 303(d) list for temperature based on exceedence of the criterion that is linked 

to dissolved oxygen. This criterion (OAR 340-41-965 (2)(b)(A)) reads: “...no measurable 

surface water temperature increase resulting form anthropogenic activities is allowed: 

... (vi) In Oregon waters when the dissolved oxygen (DO) levels are within 0.5 mg/l or 

10 percent saturation of the water column or intergravel DO criterion for a given stream 

reach or subbasin.” An additional narrative criterion would apply to these waters as 

they contain a federally listed Threatened and Endangered species - Lost River Sucker 

and Shortnose Sucker, both of which are listed as endangered (USFWS, 7/88, 

53FR27130). This criterion (OAR 340-41-965 (2)(b)(A)) states: “no measurable surface 

water temperature increase resulting form anthropogenic activities is allowed: ... (v) In 

stream segments containing federally listed Threatened and Endangered species if the 

increase would impair the biological integrity of the Threatened and Endangered 

population.” A Site Specific Criteria is currently being developed as part of a TMDL for 

these waters and a new criteria for temperature will be established. This criterion will be 

adopted by the EQC and submitted to EPA for approval prior the completion of a TMDL.

This work should be accomplished during our next triennial standards review (1998 -

2000). The TMDL schedule is currently being negotiated with EPA.

3. Warm water streams in the lower Malheur and Owyhee (Table 15 and 16) would be 

addressed in a similar manner using temperature criterion that relates to dissolved 

oxygen. These waters were not listed on the current 303(d) list as the waters were not 

within 0.5 mg/l or 10 percent saturation of the water column DO criterion. These waters 

are included in beneficial use survey work that the Department is undertaking in the 

Snake River Basin/High Desert Ecoregion. This work, which will include the 
Page 5 Appendix 2

development of numeric temperature criteria for these waters, will be accomplished 

during our next triennial standards review (1998-2000).

Willamette and Columbia River Temperature Criteria: The language in the rule (OAR 

340-41-445 (2)(b)(A)) reads: “...no measurable surface water temperature increase 

resulting from anthropogenic activities is allowed: ... (ii) In the Columbia River or its 

associated sloughs and channels from the mouth to river mile 309 when surface water 

temperatures exceed 68.0oF (20.0oC); (iii) In the Willamette River or its associated sloughs 

and channels from the mouth to river mile 50 when surface water temperatures exceed 

68.0oF (20.0oC);”

For the Columbia River, this is not a change to the previous standard (OAR 340-41-445 (2) 

(b) (D). The Columbia River forms the boundary between the states of Oregon and 

Washington and this criterion is consistent with the current temperature standard for the 

State of Washington.

For the Willamette River, this value represents a decrease from the previous temperature 

criteria of 70oF and makes it consistent with the Columbia River numeric criteria. The 

technical committee had recommended the 68oF criteria for these large, lower river 

segments recognizing that temperatures were expected to be higher in these segments as 

factors such as the naturally wide channels would minimize the ability to shade these rivers 

and reduce the thermal loading.

Both of these rivers are water quality limited for temperature and the temperature criteria 

can be revisited as part of the effort to develop Total Maximum Daily Loads. The 

Department is currently working with EPA to develop a temperature assessment for the 

Columbia River and is participating in a Willamette Basin Reservoir Study with the Corp of 

Engineers and other state agencies. The timing of specific TMDLs is currently being 

negotiated with EPA.

64o F Temperature Criteria: EPA has expressed concern that the 64oF criterion may not 

be fully protective. The Final Issue Paper on Temperature indicates that “the incidence of 

disease from Chondrococcus columnaris increases above 60-62o F and cites various 

sources for this statement (page 2-4 and Appendix D of the Final Issue Paper on 

Temperature). This is based both on observations from laboratory studies and field studies.

A review of this literature indicates that it is difficult to establish a temperature criteria for 

waters that experience diurnal temperature changes that would assure no affects due to C. 

columnaris. For example, J. Fryer and K. Pilcher (“Effects of Temperature on Diseases of 

Salmonid Fishes, EPA-660/3-73-020, 1974) conducted in the laboratory studies using 

constant temperatures and concluded:

“When coho and spring chinook salmon, and rainbow trout are infected with C. 

columnaris by water contact, the percentage of fatal infections is high at temperatures 

of 64oF and above, moderate at 59oF and approaches zero at 49oF and below. A 

temperature of 54oF is close to the threshold for development of fatal infection of 

salmonids by C. columnaris.”
Page 6 Appendix 2

There is literature that suggests that fish pathogens which affect Oregon’s cold-water fishes 

become more infective and virulent at temperatures ranging from the lower mid-sixties to 

low seventies (Becker and Fujihara, 1978). Ordal and Pacha (1963) found that mortalities 

due to C. columnaris outbreaks are lessened or cease when temperatures are reduced 

below 65oF. Bell (1986) suggested that outbreaks of high virulence strains of C. columnaris 

occur when average water temperatures reach 15.5oC and the low virulence strains 

become apparent with average water temperatures over 20oC.

A good discussion of field studies is given in the report “Columbia River Thermal Effects 

Study” (EPA, 1971).

“Natural outbreaks of columnaris disease in adult salmon have been linked to high 

water temperatures in the Fraser River, British Columbia. ...The pathological effects of 

the disease became evident when water temperatures along the migration route, and in 

spawning areas, exceeded 60oF. Prespawning mortality reached 90 percent in some 

tributaries. Columnaris is the infected sockeye spawners was controlled when 

temperatures fell below 57-58oF and mortalities were reduced. “

“Data collected on antibody levels in the Columbia River fish “...suggest peak yearly 

effective infection of at least 70 percent to 80 percent of most adult river fish species”

(Fujihara and Hungate, 1970). Occurrence of the disease was generally associated with 

temperatures above 55oF; the authors further suggest that the incidence of columnaris 

may be increased by extended periods of warm temperatures than by peak summer 

temperatures.”

“Other factors including the general condition of the fish, nutritional state, size, presence 

of toxicants, level of antibody protection, exposure to nitrogen supersaturation, level of 

dissolved oxygen, and perhaps other factors interrelate in the infection of fish by 

diseases. However, the diseases discussed here are of less importance at 

temperatures below 60oF; that is, in most instances mortalities due to columaris are 

minimized or eliminated below that level.”

As indicated in the section on “Standard Alternatives and Technical Evaluation” in the 

Temperature Issue Paper, the technical committee had recommended a temperature range 

(58 - 64oF) as being protective for salmonid rearing. While 64oF is at the upper end of the 

range, the key to this recommendation is the temperature unit (page 3-2) that is used in the 

standard - the seven-day moving average of the daily maximum temperatures. Exceedence 

of the criteria is based on the average of the daily maximum temperatures that a waterbody 

experiences over the course of seven consecutive days exceeding 64oF.

Streams experience a natural fluctuation of daily temperatures so streams that were just 

meeting the temperature standard would be experiencing temperatures over 60oF for only 

short periods of time during the day and have lower average temperatures. For example, 

the Department has summarized temperature data collected at 6 sites around the state 

which are near the 7-day average of the daily maximum of 64oF (see table below). As 

shown, the daily average temperatures typically range between 55-60oF. Risks should be 

minimized at these average temperatures.

In conclusion, the criteria does not represent an assured no-effect level. However, because 

the criteria represent a “maximum” condition, given diurnal variability, conditions will be 

better that criteria nearly all of the time at most sites. 
Page 7 Appendix 2

7-Day 

Statistic

Average Daily Temperatures

Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7

Grande Ronde Basin

East Fork Grande Ronde River 64.7 57.8 58.1 57.4 57.1 57.3 58.0 58.1

Beaver Creek (upstream La Grande Res.) 65.2 55.1 56.5 58 58.2 59.7 60.1 59.9

Umpqua Basin

Jim Creek (mouth) 62.5 58.2 59.5 59.9 60.1 58.6 55.7 56.8

Pass Creek (upper) 64.4 59.0 58.7 58.1 58.5 59.1 59.3 57.7

Tillamook Basin

Myrtle Creek (mouth) 65.0 57.7 59.1 58.6 57.9 58.0 57.6 56.8

Sam Downs Creek (mouth) 63.9 55.8 55.9 55.5 55.5 55.7 55.6 56.1

Minimum Dissolved Oxygen Criteria for Cool Water and Warm Water Species:

Warm Water: The Oregon warm water criteria for dissolved oxygen is 5.5 mg/l as a 30 day 

mean and 4.0 mg/l as a minimum. These values meet or exceed the recommended 

national criteria for warm water criteria for other life stages (5.5 mg/l as a 30 day mean and 

3.0 as a 1 day minimum as shown in Table 1 of the dissolved oxygen criteria in Quality 

Criteria for Water, 1986 (EPA 440/5-86-001)). These values are slightly below national 

criteria suggested for protection of early life stages (6.0 mg/l as a 7 day mean and 5.0 as a 

1 day minimum as shown in Table 1 of the dissolved oxygen criteria in Quality Criteria for 

Water, 1986). As shown on Table 2 of the dissolved oxygen criteria in Quality Criteria for

Water, 1986, this would represent a slight impairment for early life stages.

This criteria would be applied to both native and non-native warm water species. Table 2-3 

in the Temperature Issue Paper (page 2-14) contains a list of non-salmonid fish species 

present in Oregon. Warm water species include: Borax Chub; Cyprinids (goldfish, carp, 

fathead minnows); Centrarchids (Bluegill, Crappie, Large-mouth Bass); and Catfish. The 

only known warm-water species that is native to Oregon is the Borax Chub, which is found 

near a hot springs. The others have been introduced and now perpetuate themselves in 

some basins. These species are typically Spring spawners (April - June) during which times 

dissolved oxygen values are not at the seasonal lows (July - August) and typically have not 

been found to be a problem. In addition, salmonid spawning criteria, which are more 

protective, typically apply during these time period.

It should be noted that most of the introduced warm water species now compete with the 

native cold and cool water species for habitat and food. There are numerous recovery plans 

being developed for these native species. A level of protection that may have a slight 

production impairment for non-native warm water species is not necessarily undesirable. 
Page 8 Appendix 2

Cool Water: A cool water classification was created to protect cool water species where 

cold-water biota may be present during part or all of the year but would not form the 

dominate community structure. The cool water criteria match the national coldwater criteria 

- other life stages criteria.

Table 2-3 in the Temperature Issue Paper (page 2-14) contains a list of non-salmonid fish 

species present in Oregon. Cool water species include: Chub; Suckers; Sandroller; 

Sturgeon; Centrarchids (Small-mouth Bass); Striped Bass; and Walleye. Small mouth bass, 

striped bass and walleye are introduced species. This category was set up to provide more 

protection than that afforded by the other life stage criteria for warm water fish and, as 

discussed in the Gold Book, we provided these cool water species with the cold water 

species protection suggested in the national criteria (Table 1 of the dissolved oxygen 

criteria in Quality Criteria for Water, 1986). These species are typically Spring spawners 

(April - June) during which times dissolved oxygen values are not at the seasonal lows 

(July- August) and typically have not been found to be a problem. 

Table 2-2 of the Dissolved Oxygen Issue Paper indicates that salmonids and other coldwater biota may be present during part or all of the year but may not dominate community 

structure. Any salmonid spawning would still be covered by the salmonid spawning 

standard. The Oregon standards provide higher protection for salmonid spawning and cold 

water rearing than that recommended under the national criteria by choosing the “no 

production impairment” levels suggested in Table 2 of the dissolved oxygen criteria in 

Quality Criteria for Water, 1986.

When adequate information/data exists: The dissolved oxygen standard provides 

multiple criteria for cold, cool and warm water aquatic life. For example, OAR 340-41-445 

(2) (a) (D) reads: “For waterbodies identified by the Department as providing cold-water 

aquatic life, the dissolved oxygen shall not be less than 8.0 mg/l as an absolute minimum.

Where conditions of barometric pressure, altitude, and temperature preclude attainment of 

the 8.0 mg/l, dissolved oxygen shall not be less than 90 percent of saturation. At the 

discretion of the Department, when the Department determines that adequate information 

exists, the dissolved oxygen shall not fall below 8.0 mg/l as a 30-day mean minimum, 6.5 

mg/l as a seven-day minimum mean, and shall not fall below 6.0mg/l as an absolute 

minimum (Table 21).”

In this example, the Department would routinely compare dissolved oxygen values against 

8.0 mg/l criteria (the higher dissolved oxygen criteria). Most dissolved oxygen data is 

collected by a grab sample during the day time and would not reflect minimum conditions, 

that is why we would use a more restrictive criteria. Adequate information to use the other 

criteria would involve the collection of diurnal data over long enough periods of time (e.g. 

multiple days or multiple weeks) during critical time periods (e.g. low flow periods, hottest

water temperature periods, period of maximum waste discharge). Such data would be 

collected through continuous monitoring with proper quality assurance. Based on this data 

collection, sufficient data would be available to calculate means, minimum means and 

minimum values and to compare to the appropriate criteria. Models that would provide 

these statistics could also be compared to the appropriate criteria.

In addition, for actions such as permitting and developing TMDLs, additional information on 

the beneficial uses of the waterbody will be considered such as: species present; listing 

status of those species; locations, time periods and presence of sensitive early life stages, 
Page 9 Appendix 2

etc. Based on presence of early life stages or T&E species, the more conservative criteria 

would be used.

IMPLEMENTATION ISSUES:

Air temperature exemption to the water temperature criteria: OAR 340-41-basin (2)(b) 

(B) specifies that “an exceedence of the numeric criteria identified subparagraph (A) ... of 

this subsection will not be deemed a temperature standard violation if it occurs when the air 

temperature during the warmest seven-day period of the year exceeds the 90th percentile of 

the seven-day average daily maximum air temperature calculated in a yearly series over 

the historic record. However, during such periods, the anthropogenic sources must still 

continue to comply with their surface water temperature management plans developed 

under OAR 340-41-026(3)(a)(D).”

This policy identifies criteria to be used in certain limited circumstances to determine 

whether a violation of the temperature water quality standard has occurred. This 

interpretation would be applied for the purposes of enforcement of standards and the 

303(d) listing determinations. Our interpretation of how this air temperature exemption 

would be applied has been sent to you separately. In the 1994/96 303(d) list, no water 

bodies were excluded from the list for this reason.

Exceptions to the policy that prohibits new or increased discharged load to receiving 

streams classified as being water quality limited:

OAR 340-41-026 (3) (C) states “the new or increased discharged load shall not be granted 

if the receiving stream is classified as being water quality limited under OAR 340-41-

006(30)(a), unless...”

OAR 340-41-026 (3) (a) C (iii) added new language under this policy which defines a 

condition under which a new or increased discharged load could be allowed to a water 

quality limited waterbody for dissolved oxygen. The language states: “(iii) Effective July 1, 

1996, in waterbodies designated water-quality limited for dissolved oxygen, when 

establishing WLAs under a TMDL for waterbodies meeting the conditions defined in this 

rule, the Department may at its discretion provide an allowance for WLAs calculated to 

result in no measurable reduction of dissolved oxygen. For this purpose, “no measurable 

reduction” is defined as no more than 0.10 mg/l for a single source and no more than 0.20 

mg/l for all anthropogenic activities that influence the water quality limited segment. The 

allowance applies for surface water DO criteria and for Intergravel DO if a determination is 

made that the conditions are natural. The allowance for WLAs would apply only to surface 

water 30-day and seven-day means, and the IGDO action level.”

This is an implementation policy for OAR 340-41-026 (3) (C) and clarifies that we could 

allow for an increase in load in a waterbody that is water quality limited for dissolved oxygen 

as long as it did not result in a measurable reduction of dissolved oxygen as defined above 

and it was determined that the low DO values were due to a natural condition. A site 

specific criteria for the waterbody would need to be developed and submitted to EPA for 

review and approval.
Page 10 Appendix 2

All feasible steps: OAR 340-41-026 (3) (D) indicates that: “Sources shall continue to 

maintain and improve, if necessary, the surface water temperature management plan in 

order to maintain the cooling trend until the numeric criterion is achieved or until the 

Department, in consultation with the Designated Management Agencies (DMAs), has 

determined that all feasible steps have been taken to meet the criterion and that the 

designated beneficial uses are not being adversely impacted. In this latter situation, the 

temperature achieved after all feasible steps have been taken will be the temperature 

criterion for the surface waters covered by the applicable management plan. The 

determination that all feasible steps have been taken will be based on, but not limited to, a

site-specific balance of the following criteria: protection of beneficial uses; appropriateness 

to local conditions; use of best treatment technologies or management practices or 

measures; and cost of compliance.”

As indicated, if the waters do not come into compliance with the standard after all feasible 

steps have been taken, the Department would develop a site-specific criteria which would 

be submitted to EPA for approval pursuant to EPA policy.

1.0o F increase for new or increased discharge loads from point sources or hydropower projects in temperature water quality limited basins: OAR 340-41-026 (3) (F), 

(G), (H) state: “(F) In basins determined by the Department to be exceeding the numeric 

temperature criteria, and which are required to develop surface water temperature 

management plans, new or increased discharge loads from point source sources which 

require an NPDES permit under Section 402 of the Clean Water Act or hydro-power 

projects which require certification under Section 401 of the Clean Water Act are allowed a 

1.0oF total cumulative increase in surface water temperatures as the surface water 

temperature management plan is being developed and implemented for the water quality 

limited basin if:

(i) in the best professional judgment of the Department, the new or increased 

discharge load, even with the resulting 1.0oF cumulative increase, will not conflict 

with or impair the ability of the surface water temperature management plan to 

achieve the numeric temperature criteria; and

(ii) A new or expanding source must demonstrate that it fits within the 1.0oF increase 

and that its activities will not result in a measurable impact on beneficial uses. This 

latter showing must be made by demonstrating to the Department that the 

temperature change due to its activities will be less than or equal to 0.25oF under a 

conservative approach or by demonstrating the same to the EQC with appropriate 

modeling.

(G) Any source may petition the Department for an exception to paragraph (F) of this 

subsection, provided:

(i) The discharge will result in less than 1.0oF increase at the edge of the mixing zone, 

and subparagraph (ii) or (iii) of this paragraph applies;

(ii) The source provides the necessary scientific information to describe how the 

designated beneficial uses would not be adversely impacted; or

(iii) The source demonstrates that:

(I) It is implementing all reasonable management practices;

(II) Its activity will not significantly affect the beneficial uses; and
Page 11 Appendix 2

(III) The environmental cost of treating the parameter to the level necessary to 

assure full protection would outweigh the risk to the resource. 

OAR 340-41-026 (3) (F) and (G) reflect an implementation policy for OAR 340-41-026 (3) 

(C). They clarify under what conditions the Department could allow for an increase in load 

to a waterbody that is water quality limited for temperature as long as the load did not result 

in a measurable increase in temperature (less than or equal to 0.25oF) or a cumulative 

increase of 1.0oF under (F) but a source could petition for up to the cumulative increase of 

1.0oF under (G). The cumulative increase typically addresses the situation where there

may be multiple new or increased discharges. A TMDL would still be developed to bring the 

waterbody back into compliance with the temperature criteria. The WLA and the permit for 

the new or increased source would target the appropriate temperature criteria using a 

conservative approach as shown below (e.g. calculations would be made using 63oF so 

that the cumulative increase would not be above the standard of 64oF).40

OAR 340-41-026 (3) (H) states: “Any source or DMA may petition the Commission for an 

exception to paragraph (F) of this subsection, provided:

(i) The source or DMA provides the necessary scientific information to describe how 

the designated beneficial uses would not be adversely impacted; or

(ii) The source or DMA demonstrates that:

(I) It is implementing all reasonable management practices;

(II) Its activity will not significantly affect the beneficial uses; and

(III) The environmental cost of treating the parameter to the level necessary to 

assure full protection would outweigh the risk to the resource. “

This exemption is a variance policy in which a source can petition the Commission to allow 

the temperature to increase by a specified amount for a limited period of time in order to 

allow for new or increased point source discharges to water quality limited waters until a 

TMDL is prepared. The variance would be submitted to EPA for review and approval.

These variances would be reviewed again during the development of a TMDL or at permit 

renewal.

 

40 Examples of various of discharge scenarios using a conservative mass balance analysis. The odd numbered examples 

show a scenario when the stream meets standards. The subsequent even numbered example shows the scenario when the 

stream is above standard. Examples 1 - 4 would be addressed under OAR 340-41-026 (3) (F); examples 5 - 8 would be 

addressed under OAR 340-41-026 (3) (G); and examples 9 - 10 would be addressed under OAR 340-41-026 (3) (H).

Example Upstream Effluent Downstream Change in

Flow Temp Flow Temp Flow Temp Temp

1 10 63 0.4 69.5 10.4 63.25 0.25

2 10 73 0.4 69.5 10.4 72.87 -0.13

3 10 63 0.1 88 10.1 63.25 0.25

4 10 73 0.1 88 10.1 73.15 0.15

5 10 63 0.4 79.5 10.4 63.63 0.63

6 10 73 0.4 79.5 10.4 73.25 0.25

7 10 63 0.4 89 10.4 64.00 1.00

8 10 73 0.4 89 10.4 73.62 0.62

9 10 61.5 1 89 11 64.00 2.50

10 10 73 1 89 11 74.45 1.45
Page 12 Appendix 2

Source Petition for an exception to temperature criteria: OAR 340-41-basin (2)(b)(C) 

specifies that “Any source may petition the Commission for an exception to subparagraph 

(A)...of this subsection for discharge above the identified criteria if: (i) The source provides 

the necessary scientific information to describe how the designated beneficial uses would 

not be adversely impacted; or (ii) a source is implementing all reasonable management 

practices or measures; its activity will not significantly affect the beneficial uses; and the 

environmental cost of treating the parameter to the level necessary to assure full protection 

would outweigh the risk to the resource.”

This will be, for most cases, a variance policy which allows the temperature to increase by a 

specified amount for a limited period of time in order to allow for an existing point source to 

discharge to water quality limited waters until a TMDL is prepared. In the case where that 

source would be the major cause for the temperature criteria to be exceeded and a TMDL 

would not be developed for that waterbody to bring it back into compliance, a site specific 

criteria would be developed and submitted to EPA for approval.

pH Standard exception: OAR 340-41-basin (2) (d) states “The following exception 

applies: Waters impounded by dams existing on January 1, 1996, which have pHs that 

exceed the criteria shall not be considered in violation of the standard if the Department 

determines that the exceedence would not occur without the impoundment and that all 

practicable measures have been taken to bring the pH in the impounded waters into 

compliance with the criteria.”

This language was intended to address the situation where a hydroproject would be 

applying for a 401 re-certification and it was found that the action of impounding the waters 

caused algal growth which caused the reservoir to subsequently exceed the pH standard.

This might set up the situation where the only way to re-certify the project would be to 

destroy the dam which may not be the preferred option. In the cases where this exception 

would be applied, the Department would develop either a TMDL for nutrients in the 

upstream watershed, develop a site specific criteria for the waterbody or develop a use 

attainability analysis to modify the uses for portions of the reservoir.

Final Note: ODFW has a great deal of knowledge regarding location and timing for 

presence, spawning, etc of fish in Oregon streams. Much of this information is either in the 

files contained in local field offices or is gained from the judgment of the local biologist. Until 

recently, it has not been mapped. A mapping effort is underway and is furthest along for 

Bull Trout and Anadromous fish species. There is a coordinated effort underway entitled 

“StreamNet” (www.streamnet.org). This work is focused on a species by species mapping 

which would need to be generalized to match cold, cool, warm-water classification and 

spawning vs rearing groupings indicated in the standards. Issues such as mapping scales 

and coverage would still need to be worked out. This effort, to better categorize aquatic life 

uses, could be addressed in subsequent triennial standards reviews but will need additional 

funding to complete.

There are quite a number of standards related issues that are candidates for consideration 

during the next triennial review. ODEQ and EPA should get together once ODEQ has hired 

a new standards coordinator to discuss priorities and approaches for conducting the next 

triennial review process.
Page 13 Appendix 2

Please feel to contact Andy Schaedel (503-229-6121) or Lynne Kennedy (503-229-5371) if 

you have further questions.

Sincerely,

Michael T. Llewelyn

Administrator, Water Quality Division

cc: Water Quality Managers
Appendix 3

February 4, 2004

Mr. Randy Smith, Director

Office of Water

U.S. EPA Region 10

1200 Sixth Avenue

Seattle, WA 98101

Re: Oregon Responses to EPA Questions re the State’s water quality temperature 

standards

Dear Mr. Smith:

This letter is a follow up to our similar correspondence of December 19, 2003, which 

described Oregon’s newly adopted antidegradation and temperature rules. There are three 

purposes for this letter. First, we are offering similar clarifications regarding the State’s 

intended methodology for identifying natural conditions for parameters other than 

temperature. Second, we are commenting on several proposed conservation measures 

EPA is developing pursuant to consultation under the Endangered Species Act. Finally, 

we are providing your Agency with information on the application of the dissolved 

oxygen criteria to resident fish spawning.

Natural Conditions

As we indicated in our earlier letter, our revised rules make it clear that where ODEQ

identifies a natural condition which is less stringent than the numeric criteria set out in 

the State’s water quality standards, the natural condition supercedes the numeric criteria.

Very similar language appeared in our previous rules, which were previously approved 

by EPA.

By definition, “natural conditions” are those pollutants that are present in the State’s 

waters that are not attributable to anthropogenic activities. Rather, these conditions are 

caused by local geophysical, hydrological and meteorological processes and wildlife.

ODEQ anticipates that site-specific natural conditions might be identified for the 

following parameters:

 Bacteria (attributed to wildlife)

 Metals (attributed to naturally eroding ore deposits)

 Nutrients (attributed to background soil, vegetation and/or wildlife conditions)

 Sediments and Turbidity (attributed to soil erosion and/or organic matter not 

accelerated by human activities)

Oregon

 Theodore Kulongoski, Governor

Department of Environmental Quality

Headquarters

811 SW Sixth Avenue

Portland, OR 97204-1390

(503) 229-5696

FAX (503)229-6124

TTY (503) 229-6993
Appendix 3

 Other parameters attributed to similar natural processes.

Prior to a natural condition superceding otherwise applicable numeric criteria, ODEQ

will make a finding as to the level at which the pollutant is present with no influence 

from anthropogenic activities. Similarly, ODEQ will document the natural process 

contributing to the presence of the pollutant. The specific methodology used to support a 

natural condition finding may vary in each local situation. However, in general the 

methodologies used will be similar to that described in our December 19, 2003 letter:

 Reference streams,

 Pollutant transport models,

 DNA testing, 

 Historical data (where available) and/or

 Other sampling methods and studies.

The public will have specific notice of these natural conditions whenever they are 

relevant to one of the Clean Water Act regulatory programs. The public notices and 

documentation accompanying the biannual 303(d) listing process, draft TMDLs, draft 

NPDES permits and 401 water quality certifications will indicate that the otherwise 

applicable numeric criteria have been superceded by a natural conditions finding.

Moreover, since 303(d) listings and TMDLs are transmitted to EPA for approval, the 

Agency will have an opportunity to review ODEQ ’s natural conditions conclusions.

ODEQ is committed to work with EPA as natural condition methodologies are refined in 

the TMDL, NPDES and 303(d) listing contexts.

ODEQ expects that natural conditions will most commonly be identified through the 

TMDL process. In that circumstance, EPA will have an opportunity to review and 

evaluate any natural condition determination as part of its TMDL approval action. ODEQ

will list the water bodies where “natural conditions” findings have been made on our 

standards web page to ensure that the public is aware and notified of natural conditions, 

It should be noted that it is possible, at some locations in the State, that the natural 

condition will not support, and never has supported a designated beneficial use. In such 

circumstances, ODEQ will modify the designated use to properly adjust the beneficial 

use to better reflect the existing use of the water segment. 

Proposed Conservation Measures 

ODEQ is aware that EPA is considering several conservation measures associated with 

its approval of the State water quality standards revisions. EPA has inquired whether 

ODEQ would participate in these conservation measures if they are pursued. To begin 

with, ODEQ notes that most of these conservation measures pursue information on the 

future implementation of the State’s standards. They are best categorized as efforts 

intended to identify additional information supporting the use of our standards once they 

are in place.
Appendix 3

Since Oregon has a strong interest in these federal initiatives, ODEQ will, resources 

allowing, participate in the proposed conservation measures as described in EPA’s 

Biological Evaluation: Temperature Monitoring and Use Designations (2.5.1) and the 

Two Year Review (2.5.2).

Dissolved Oxygen and Spawning

The revised Oregon rules clarified spawning locations and timing for anadromous fish 

and Lahontan Cutthroat Trout. Due to a lack of site specific data for species other than 

these, and since temperature criteria for spawning were not established for other species, 

no similar clarification was made for resident trout (i.e., rainbow, redband, Westslope 

cutthroat and coastal cutthroat) or char (bull trout) spawning. However, the dissolved 

oxygen criteria contain provisions that continue to apply to resident trout and char 

spawning areas. ODEQ will use the following dates to apply the dissolved oxygen 

spawning criteria (throughout the range where the Oregon maps indicate trout rearing, 

redband trout and core cold water habitat uses are identified). 

Resident Trout Spawning (Redband, Rainbow, Westslope and Coastal Cutthroat)

 For waters designated as trout rearing, or redband trout use, spawning is deemed 

to occur from January 1 – May 15 each year;

 For waters designated as core cold water habitat, or bull trout spawning and 

rearing use, resident trout spawning is deemed to occur from January 1 – June 15 

each year; and 

 For trout rearing waters upstream from core cold water habitat, spawning is also 

deemed to occur from January 1 – June 15 each year.

Char (Bull Trout) Spawning

The following dates apply to all reaches designated as having “bull trout spawning and 

rearing use” within the specified basin or subbasin:

Basin Subbasin Spawning Period Source of Information

South Willamette Aug 15 – May 30 ODFW

John Day Sept 1 – April 30 ODFW

Umatilla Sept 1 – April 30 ODFW
Appendix 3

Walla Walla Sept 1 – April 30 ODFW

Grand Ronde Upper G. R. Sept 1 – April 15 ODFW

 Wallowa Sept 1 – May 15 ODFW

 Wenaha Aug 15 – March 31 ODFW

Imnaha Aug 15 – May 31 ODFW

Hood Aug 15 – May 15 USFWS

Deschutes Aug 15 – May 15 USFWS

Powder Aug 15 – May 15 USFWS

Malheur Aug 15 – May 30 USFWS

Klamath Aug 15 - May 30 USFWS

This timing information will be circulated to ODEQ field staff responsible for 

implementing the dissolved oxygen criteria. ODEQ will continue to refine all of these 

designations as more information is developed on resident trout and char spawning 

activities. 

Oregon looks forward to EPA’s review and approval of our water quality standards. If 

you require any additional information or clarification of these rules, please contact me or 

have your staff call Mark Charles, water quality standards manager at (503) 229-5589. 

Sincerely, 

Michael T. Llewelyn, Administrator

Water Quality Program

Cc: Stephanie Hallock - ODEQ 

Mark Charles - ODEQ 

Paula van Haagen - EPA

Mary Lou Soscia - EPA