Policy for Implementation of Toxics Standards for 

Inland Surface Waters, Enclosed Bays, and 

Estuaries of California 

2005 

STATE WATER RESOURCES CONTROL BOARD 

California Environmental Protection Agency
For further information regarding this publication, please contact the Division of Financial Assistance at (916) 341-5700.

STATE OF CALIFORNIA

Arnold Schwarzenegger, Governor

CALIFORNIA ENVIRONMENTAL PROTECTION AGENCY

Dr. Alan Lloyd, Secretary

STATE WATER RESOURCES

CONTROL BOARD

P.O. Box 100

Sacramento, CA 95812-0100

(916) 341-5250

Celeste Cantú, Executive Director

Harry M. Schueller, Chief Deputy Director

Thomas Howard, Deputy Director

Homepage: http://www.swrcb.ca.gov

Pete S. Silva, Member

Arthur G. Baggett, Jr., Chair

Richard Katz, Member

Gary M. Carlton, Member

Nancy H. Sutley, Member
STATE WATER BOARD

RESOLUTION NO. 2005-0019

ADOPT AMENDMENTS TO THE POLICY FOR

IMPLEMENTATION OF TOXICS STANDARDS FOR

INLAND SURFACE WATERS, ENCLOSED BAYS,

AND ESTUARIES OF CALIFORNIA (SIP)

WHEREAS:

1. In March 2000, the State Water adopted the SIP, which implements criteria for priority toxic

pollutants contained in the California Toxics Rule promulgated by the U.S. Environmental

Protection Agency (USEPA) as well as other priority toxic pollutant criteria and objectives.

2. Section 303 of the federal Water Pollution Control Act (Clean Water Act) mandates that

water quality standards be reviewed and revised, as necessary, at least once every three years.

As part of the standards development program, the State Water Board periodically review its

policies.

3. In October 2002, the State Water Board solicited comments on potential revisions to the SIP.

4. In December 2002, approximately 313 comments were received from 26 individuals and

organizations.

5. State Water Board staff reviewed, carefully considered, and responded to all comments

received.

6. State Water Board staff prepared an August 2003 report that contains recommendations for

revisions to the SIP. Staff’s recommended revisions are those that will improve the SIP’s

clarity and functionality and that can be made in a reasonable amount of time with existing

resources.

7. The State Water Board notified interested parties of its recommended SIP revisions and

provided an additional 30-day comment period.

8. The State Water Board held a public workshop on September 30, 2003 regarding issues to be

addressed in future SIP amendments.

9. The State Water Board adopted Resolution No. 2003-0070 authorizing staff to prepare draft

amendments and support documents to the SIP on October 15, 2003.

10. State Water Board staff completed the revisions to the SIP and provided a functional

equivalent document for public review on December 15, 2004.

11. In January 2005, public comments were received from six organizations regarding the

proposed amendment documents.

12. The State Water Board held a public hearing on February 2, 2005 regarding the proposed SIP

amendments and addressed public comments.
-2-

13. In Order WQO 2003-0012, the State Water Board determined that (1) the propriety of

including numeric effluents for chronic toxicity in NPDES permits for publicly-owned

treatment works should be considered in a regulatory setting, in order to allow for full public

discussion and deliberation; and (2) the SIP be modified to specifically address the issue.

THEREFORE BE IT RESOLVED THAT:

The State Water Board:

1. Adopts amendments to the SIP (Attachment A) that:

a. Allow water effects ratios to be established in individual National Pollutant Discharge

Elimination System permits, rather than in the Basin Planning process as currently

required.

b. Eliminate the reasonable potential trigger for situations where ambient background

pollutant concentrations are greater than a priority pollutant objective or criterion.

c. Make non-regulatory language corrections to improve clarity.

d. Add mutual water companies to section 5.3 (exceptions).

2. Authorizes the State Water Board Executive Director to sign the Certificate of Fee

Exemption (Attachment B).

3. Authorizes the State Water Board Executive Director or designee to submit the SIP revisions

to the Office of Administrative Law and the USEPA for final approval.

4. Directs staff to introduce an amendment to the SIP to address narrative toxicity control

provisions by January 2006.

CERTIFICATION

The undersigned, Clerk to the Board, does hereby certify that the foregoing is a full, true, and

correct copy of a resolution duly and regularly adopted at a meeting of the State Water Board

held on February 24, 2005.
3/17/2005 

1

Table of Contents 

Section Page

Table of Contents ......................................................................................................................... 1 

Introduction .................................................................................................................................. 3

1 ESTABLISHING WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR 

PRIORITY POLLUTANT CRITERIA/OBJECTIVES ...................................................... 4 

1.1 Applicable Priority Pollutant Criteria and Objectives.............................................4 

1.2 Data Requirements and Adjustments ...................................................................... 5 

1.3 Determination of Priority Pollutants Requiring Water Quality-Based Effluent 

Limitations......................................................................................................... 5 

1.4 Calculation of Effluent Limitations......................................................................... 7 

1.4.1 Translators for Metals and Selenium.......................................................14 

1.4.2 Mixing Zones and Dilution Credits .........................................................15 

1.4.2.1 Dilution Credits...................................................................... 15 

1.4.2.2 Mixing Zone Conditions........................................................17 

1.4.3 Ambient Background Concentrations...................................................... 18 

1.4.3.1 Ambient Background Concentration as an 

 Observed Maximum ....................................................... 18 

1.4.3.2 Ambient Background Concentration as an 

Arithmetic Mean............................................................. 18 

1.4.4 Intake Water Credits ................................................................................ 19 

2 DETERMINING COMPLIANCE WITH PRIORITY POLLUTANT CRITERIA/ 

OBJECTIVES AND WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR 

PRIORITY POLLUTANT CRITERIA/OBJECTIVES .................................................... 20 

2.1 Compliance Schedules .......................................................................................... 20 

2.1.1 TMDL-Based Compliance Schedule...................................................... 21 

2.2 Interim Requirements ............................................................................................ 22 

2.2.1 Interim Requirements Under a Compliance Schedule.......................... 22 

2.2.2 Reserved................................................................................................ 22 

2.3 Monitoring Requirements...................................................................................... 22 

2.4 Reporting Requirements........................................................................................ 23 

2.4.1 Reporting Levels...................................................................................... 23 

2.4.2 Selection and Use of Appropriate Minimum Level (ML) Value............. 23 

2.4.3 Deviation from MLs Listed in Appendix 4 ............................................. 24 

2.4.4 Reporting Protocols ................................................................................. 25 

2.4.5 Compliance Determination ...................................................................... 25 

 2.4.5.1 Pollutant Minimization Program .............................................. 26 

3 2,3,7,8-TCDD EQUIVALENTS ....................................................................................... 27 

4 TOXICITY CONTROL PROVISIONS............................................................................ 29 

5 SPECIAL PROVISIONS .................................................................................................. 30 

5.1 Non-Point Source Discharges ...............................................................................30 

5.2 Site-Specific Objectives ........................................................................................ 30 

5.3 Exceptions ............................................................................................................. 32 
3/17/2005 

2

Appendix 1 Definition of Terms.................................................................................1-1 

Appendix 2 Determination of Pollutants Requiring Water Quality-Based 

Effluent Limitations (flowchart).............................................................2-1 

Appendix 3 U.S. Environmental Protection Agency Conversion Factors .................3-1 

Appendix 4 Minimum Levels (MLs) .........................................................................4-1 

Appendix 5 Special Studies Guidance........................................................................5-1 

Appendix 6 Watershed Management and TMDLs.....................................................6-1 
3

 

POLICY FOR IMPLEMENTATION OF TOXICS STANDARDS 

FOR INLAND SURFACE WATERS, ENCLOSED BAYS, 

AND ESTUARIES OF CALIFORNIA

INTRODUCTION

This state policy for water quality control (Policy), adopted by the State Water Resources 

Control Board on March 2, 2000 and effective by May 22, 2000 (See “Note” below), applies to 

discharges of toxic pollutants into the *inland surface waters, *enclosed bays, and *estuaries of 

California subject to regulation under the State's Porter-Cologne Water Quality Control Act 

(Division 7 of the Water Code) and the federal Clean Water Act (CWA). Such regulation may 

occur through the issuance of National Pollutant Discharge Elimination System (NPDES) 

permits, or other relevant regulatory approaches.1

 The goal of this Policy is to establish a 

standardized approach for permitting discharges of toxic pollutants to non-*ocean surface waters 

in a manner that promotes statewide consistency. As such, this Policy is a tool to be used in 

conjunction with watershed management approaches and, where appropriate, the development of 

Total Maximum Daily Loads (TMDLs) to ensure achievement of water quality standards (i.e., 

water quality criteria or objectives, and the beneficial uses they are intended to protect, as well as 

the State and federal antidegradation policies). 

This Policy establishes: (1) implementation provisions for priority pollutant criteria promulgated 

by the U.S. Environmental Protection Agency (U.S. EPA) through the National Toxics Rule 

(NTR)2

 (promulgated on December 22, 1992 and amended on May 4, 1995) and through the 

California Toxics Rule (CTR)3, and for priority pollutant objectives established by Regional 

Water Quality Control Boards (RWQCBs) in their water quality control plans (basin plans)4; 

(2) monitoring requirements for 2,3,7,8-TCDD equivalents; and (3) chronic toxicity control 

provisions. In addition, this Policy includes special provisions for certain types of discharges 

and factors that could affect the application of other provisions in this Policy. 

Note: This Policy was effective on April 28, 2000 with respect to the priority pollutant criteria promulgated by the 

U.S. EPA through the National Toxics Rule and to the priority pollutant objectives established by Regional Water Quality 

Control Boards in their water quality control plans (basin plans), with the exception of the provision on alternate test 

procedures in section 2.3., item (1). The alternate test procedures provision was effective on May 22, 2000. This Policy 

was effective on May 18, 2000 with respect to the priority pollutant criteria promulgated by the U.S. EPA through the 

California Toxics Rule. 

1

 This Policy does not apply to discharges of toxic pollutants from combined sewer overflows. These discharges will 

continue to be regulated in accordance with the federal “Combined Sewer Overflow (CSO) Control Policy,” published 

April 19, 1994 (59 Fed. Register 18688-18698). This Policy does not apply to regulation of storm water discharges. 

The SWRCB has adopted precedential decisions addressing regulation of municipal storm water discharges in 

Orders WQ 91-03, 91-04, 96-13, 98-01, 99-05, and 2001-15. The SWRCB has also adopted two statewide general 

permits regulating the discharge of pollutants contained in storm water from industrial and construction activities. See 

SWRCB Orders 99-08-DWQ and 97-03-DWQ. This Policy does not apply to regulation of nonpoint source 

discharges. 2

 40 CFR 131.36 

3

 65 Fed. Register 31682-31719 (May 18, 2000), adding Section 131.38 to 40 CFR. 

4

 If a water quality objective and a CTR criterion are in effect for the same priority pollutant, the more stringent of the 

two applies.
4

 

With the exception of Appendix 5 (Special Studies) and Appendix 6 (Watershed Management 

and TMDLs), the provisions of this Policy have full regulatory effect. Appendix 5 is provided as 

guidance that may be followed in planning and conducting special studies that may be needed to 

implement the provisions of this Policy. Appendix 6 is provided as information on the role of 

watershed management approaches and TMDL development in achieving water quality 

standards. 

Except as provided in section 4, this Policy supersedes basin plan provisions to the extent that 

(1) they apply to implementation of water quality standards for priority pollutants, and (2) they 

regard the same subject matter as that addressed in this Policy with respect to priority pollutant 

standards. For example, the Policy supersedes basin plan mixing zone provisions to the extent 

that they apply to implementation of water quality standards for priority pollutants. 

Reference to a RWQCB also refers to SWRCB, where appropriate. Terms indicated with an 

asterisk (*) are defined in Appendix 1. 

1. ESTABLISHING WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR 

PRIORITY POLLUTANT CRITERIA/OBJECTIVES

The following sections address the issues of: (1) applicable priority pollutant criteria and 

objectives (section 1.1); (2) data requirements and adjustments (section 1.2); (3) determining 

priority pollutants requiring water quality-based effluent limitations (section 1.3); (4) calculating 

effluent limitations (section 1.4); (5) translators for metals and selenium (section 1.4.1); 

(6) mixing zones and dilution credits (section 1.4.2); (7) ambient background concentrations 

(section 1.4.3); and (8) intake water credits (section 1.4.4). Notwithstanding the provisions of 

these sections, effluent limitations must protect beneficial uses and comply with the State and 

federal antidegradation policies5

, federal antibacksliding requirements6, and other applicable 

provisions of law. 

1.1 Applicable Priority Pollutant Criteria and Objectives 

Federal water quality criteria and State water quality objectives for priority pollutants have been 

established for non-ocean surface waters of California by the U.S. EPA and some RWQCBs, 

respectively. Federal priority pollutant criteria have been promulgated by the U.S. EPA in the 

1992 NTR (amended in 1995) and in the 2000 CTR. For California, the criteria in the CTR 

supplement the criteria in the NTR (i.e., the CTR does not change or supersede any criteria 

previously promulgated for California in the NTR, but it does include them in the table of 

criteria for convenience). State priority pollutant objectives are contained in RWQCB basin 

plans.4

The RWQCB basin plans designate the beneficial uses that apply to the surface water bodies 

within their respective regions. Priority pollutant criteria/objectives are specifically established 

for the protection of aquatic life and human health beneficial uses designated in basin plans. 

Aquatic life criteria/objectives are established for fresh and salt waters. The CTR specifies the 

salinities to which the freshwater and saltwater criteria apply. The CTR also states that, except 

5

 SWRCB Resolution No. 68-16 (Statement of Policy with Respect to Maintaining High Quality of Waters in 

California), and 40 CFR 131.12 (revised as of July 1, 1996), respectively. 6

 CWA Sections 402(o)(1) and 303(d)(4), and 40 CFR 122.44(l) and 40 CFR 122.62 (revised as of July 1, 1996).
5

as specified in the CTR, the federal criteria apply to all waters assigned any aquatic life or 

human health use designated in basin plans. It further states that the application of the criteria 

are based on the presence in all waters of some aquatic life designation and the presence or 

absence of the municipal and domestic supply (MUN) designation (i.e., the aquatic life criteria 

and the human health criteria for consuming water and organisms apply to MUN-designated 

water bodies; the aquatic life criteria and the human health criteria for consuming organisms 

only apply to non-MUN water bodies). 

Designated beneficial uses to which aquatic life criteria or objectives would apply include, but 

are not necessarily limited to, warm freshwater habitat (WARM), cold freshwater habitat 

(COLD), and estuarine habitat (EST). Designated beneficial uses to which human health 

criteria/objectives would apply include, but are not necessarily limited to, municipal and 

domestic supply (MUN) and water contact recreation (REC1). Human health criteria/objectives 

are differentiated by whether organisms alone from the water body are consumed compared to 

whether both organisms and water from the water body are consumed. Where MUN is 

designated, the latter situation applies. 

1.2 Data Requirements and Adjustments 

The RWQCB may adjust the criteria/objective for metals with *discharger-specific Water Effect 

Ratios established in accordance with U.S. EPA guidance – Interim Guidance on Determination 

and Use of Water Effect Ratios for Metals (EPA-823-B-94-001) or Streamlined Water-Effect 

Ratio Procedure for Discharges of Copper (EPA-822-R-01-005), if appropriate7

. 

It is the discharger’s responsibility to provide all data and other information requested by the 

RWQCB before the issuance, reissuance, or modification of a permit to the extent feasible. 

When implementing the provisions of this Policy, the RWQCB shall use all available, valid, 

relevant, representative data and information, as determined by the RWQCB. The RWQCB shall 

have discretion to consider if any data are inappropriate or insufficient for use in implementing 

this Policy. Instances where such consideration is warranted include, but are not limited to, the 

following: evidence that a sample has been erroneously reported or is not representative of 

effluent or ambient receiving water quality; questionable quality control/quality assurance 

practices; and varying seasonal conditions. The lack of a site-specific objective for a priority 

pollutant shall not be considered insufficient data. 

When implementing the provisions of this Policy, the RWQCB shall ensure that 

criteria/objectives are properly adjusted for hardness or pH, if applicable, using the hardness or 

pH values for the receiving water, and that translators are appropriately applied (in accordance 

with section 1.4.1), if applicable. The RWQCB shall also ensure that pollutant and flow data are 

expressed in the appropriate forms and units for purposes of comparability and calculations.

 1.3 Determination of Priority Pollutants Requiring Water Quality-Based Effluent 

Limitations

The RWQCB shall conduct the analysis in this section for each priority pollutant with an 

applicable criterion or objective, excluding priority pollutants for which a Total Maximum Daily 

Load (TMDL) has been developed, to determine if a water quality-based effluent limitation is 

 

7

 A Water Effect Ratio may also be used to develop a site-specific metal objective, as described in Section 5.2. 
6

required in the discharger’s permit. It is the discharger’s responsibility to provide all 

information requested by the RWQCB for use in the analysis. The RWQCB shall use all 

available, valid, relevant, representative information, as described in section 1.2, to determine 

whether a discharge may: (1) cause, (2) have a reasonable potential to cause, or (3) contribute to 

an excursion above any applicable priority pollutant criterion or objective. If the following 

analysis (which is depicted as a flowchart in Appendix 2) indicates that a limitation for a 

pollutant is required, the RWQCB shall establish the limitation in accordance with section 1.4. 

Within each step below, if it is necessary to express a dissolved metal or selenium value as total 

recoverable and a site-specific translator has not yet been developed, as described in section 

1.4.1, the RWQCB shall use the applicable U.S. EPA conversion factor (Appendix 3). 

Step 1: Identify applicable water quality criteria and objectives for priority pollutants as 

described in section 1.1. Determine the lowest (most stringent) water quality criterion or 

objective for the pollutant applicable to the receiving water (C). Adjust the criterion or objective 

for hardness and/or pH, if applicable, as described in section 1.2. 

Step 2: Identify all effluent data for the pollutant as described in section 1.2 and proceed with 

Step 3. If effluent data are unavailable or insufficient, as described in section 1.2, proceed with 

Step 5. 

Step 3: Determine the observed maximum pollutant concentration for the effluent (MEC). If the 

pollutant was detected, proceed with Step 4. If the pollutant was not detected in any of the 

effluent samples and any of the reported detection limits are below the C, use the lowest 

detection limit as the MEC and proceed with Step 4. If the pollutant was not detected in any of 

the effluent samples and all of the reported detection limits are greater than or equal to the C 

value, proceed with Step 5. 

Step 4: Adjust the MEC from Step 3, if applicable, as described in section 1.2. Compare the 

MEC from Step 3 or the adjusted MEC to the C from Step 1. If the MEC is greater than or equal 

to the C, an effluent limitation is required and the analysis for the subject pollutant is complete. 

If the MEC is less than the C, proceed with Step 5. 

Step 5: Determine the observed maximum ambient background concentration for the pollutant 

(B) as described in section 1.4.3.1. If the pollutant was detected, proceed with Step 6. If B data 

are unavailable or insufficient, as described in section 1.2, proceed with Step 7. 

Step 6: Adjust the B from Step 5, if applicable, as described in section 1.2. Compare the B from 

Step 5 or the adjusted B to the C from Step 1. If the B is greater than the C and the pollutant is 

detected in the effluent, an effluent limitation is required and the analysis for the subject 

pollutant is complete. If B is greater than the C and the pollutant was not detected in any of the 

effluent samples, effluent monitoring is required (as described in Step 8) proceed with Step 7. If 

the B is less than or equal to the C, proceed with Step 7. 

Step 7: Review other information available to determine if a water quality-based effluent 

limitation is required, notwithstanding the above analysis in Steps 1 through 6, to protect 

beneficial uses. 
7

Information that may be used to aid in determining if a water quality-based effluent limitation is 

required includes: the facility type, the discharge type, solids loading analysis, lack of dilution, 

history of compliance problems, potential toxic impact of discharge, fish tissue residue data, 

water quality and beneficial uses of the receiving water, CWA 303(d) listing for the pollutant, 

the presence of endangered or threatened species or critical habitat, and other information. If 

data or other information is unavailable or insufficient, as described in section 1.2, to determine 

if a water quality-based effluent limitation is required, proceed with Step 8. 

Step 8: If data are unavailable or insufficient, as described in section 1.2, to conduct the above 

analysis for the pollutant, or if all reported detection limits of the pollutant in the effluent are 

greater than or equal to the C value, the RWQCB shall require additional monitoring for the 

pollutant in place of a water quality-based effluent limitation. Upon completion of the required 

monitoring, the RWQCB shall use the gathered data to conduct the analysis in Steps 1 through 7

above and determine if a water quality-based effluent limitation is required. If, upon completion 

of the monitoring required by Step 8 and the subsequent analysis in Steps 1 through 7, a specific 

pollutant was not detected in any effluent or if ambient background sample and applicable 

detection limits are greater than or equal to the C value, the RWQCB may require periodic 

monitoring of the pollutant. 

The RWQCB shall require periodic monitoring (at least once prior to the issuance and reissuance 

of a permit) for pollutants for which criteria or objectives apply and for which no effluent 

limitations have been established; however, the RWQCB may choose to exempt low volume 

discharges, determined to have no significant adverse impact on water quality, from this 

monitoring requirement. 

 1.4 Calculation of Effluent Limitations

When a RWQCB determines, using the procedures described in section 1.3, that water 

quality-based effluent limitations are necessary to control a priority pollutant in a discharge, the 

permit shall contain effluent limitations developed using one or more of the following methods: 

A. If a TMDL is in effect, assign a portion of the loading capacity of the receiving water to each 

identified priority pollutant source of waste, point and non-point, based on the TMDL (see 

Appendix 6); 

B. Use the following procedure based on a steady-state model: 

 Step 1: For each priority pollutant identified in section 1.3, identify the applicable water 

quality criteria/objectives for the pollutant as described in section 1.1. Adjust the criterion or 

objective, if applicable, as described in section 1.2. If it is necessary to express a dissolved 

metal or selenium criterion/objective as total recoverable and a site-specific translator has not 

yet been developed, as described in section 1.4.1, the RWQCB shall use the applicable 

U.S. EPA conversion factor (Appendix 3). If data are insufficient to calculate the effluent 

limitation, the RWQCB shall establish interim requirements in accordance with section 2.2.2.
8

Step 2: For each water quality criterion/objective, calculate the effluent concentration allowance 

(ECA) using the following steady-state mass balance equation: 

 ECA = C + D (C - B) when C > B, and 

 ECA = C when C ≤ B, 

 

 where C = the priority pollutant criterion/objective, adjusted (as described in 

section 1.2), if necessary, for hardness, pH, and translators (as described 

in section 1.4.1); 

 D = the dilution credit (as determined in section 1.4.2); and 

 B = the ambient background concentration. The ambient background 

concentration shall be the observed maximum as determined in 

accordance with section 1.4.3.1 with the exception that an ECA

calculated from a priority pollutant criterion/objective that is intended to 

protect human health from carcinogenic effects shall use the ambient 

background concentration as an arithmetic mean determined in 

accordance with section 1.4.3.2. 

 The concentration units for C and B must be identical. Both C and B shall be expressed as 

total recoverable, unless inappropriate. The dilution credit is unitless. 

 Step 3: For each ECA based on an aquatic life criterion/objective, determine the long-term 

average discharge condition (LTA) by multiplying the ECA with a factor (multiplier) that 

adjusts for effluent variability. The multiplier shall be calculated as described below, or shall 

be found in Table 1. To use Table 1, the *coefficient of variation (CV) for the effluent 

pollutant concentration data must first be calculated. If (a) the number of effluent data points 

is less than ten, or (b) at least 80 percent of the data are reported as not detected, the CV shall 

be set equal to 0.6. When calculating CV in this procedure, if an effluent data point is below 

the detection limit for the pollutant in that sample, one-half of the detection limit shall be 

used as a value in the calculations. Multipliers for acute and chronic criteria/objectives that 

correspond to the CV can then be found in Table 1. 

ECA Multipliers

ECA multiplieracute99 = e(0.5σ

2

 - zσ)

ECA multiplierchronic99 = e(0.5σ4

2

 - zσ4)

Where σ = *standard deviation 

σ = [ln(CV2

 + 1)]0.5 

σ

2

 = ln(CV2 + 1) 

σ4 = [ln(CV2

/4 + 1)]0.5

σ4

2

 = ln(CV2/4 + 1) 

z = 2.326 for 99th percentile probability basis 
9

Table 1. Effluent Concentration Allowance (ECA) 

Multipliers for Calculating Long-Term Averages (LTAs)

Coefficient 

Of 

Variation 

(CV) 

Acute Multiplier 

99th

Percentile 

Occurrence Probability 

Chronic Multiplier 

99th

Percentile 

Occurrence Probability 

0.1 

0.2 

0.3 

0.4 

0.5 

0.797 

0.643 

0.527 

0.440 

0.373 

0.891 

0.797 

0.715 

0.643 

0.581 

0.6 

0.7 

0.8 

0.9 

1.0 

0.321 

0.281 

0.249 

0.224 

0.204 

0.527 

0.481 

0.440 

0.404 

0.373 

1.1 

1.2 

1.3 

1.4 

1.5 

0.187 

0.174 

0.162 

0.153 

0.144 

0.345 

0.321 

0.300 

0.281 

0.264 

1.6 

1.7 

1.8 

1.9 

2.0 

0.137 

0.131 

0.126 

0.121 

0.117 

0.249 

0.236 

0.224 

0.214 

0.204 

2.1 

2.2 

2.3 

2.4 

2.5 

0.113 

0.110 

0.107 

0.104 

0.102 

0.195 

0.187 

0.180 

0.174 

0.168 

2.6 

2.7 

2.8 

2.9 

3.0 

0.100 

0.098 

0.096 

0.094 

0.093 

0.162 

0.157 

0.153 

0.148 

0.144 

3.1 

3.2 

3.3 

3.4 

3.5 

0.091 

0.090 

0.089 

0.088 

0.087 

0.141 

0.137 

0.134 

0.131 

0.128 

3.6 

3.7 

3.8 

3.9 

4.0 

0.086 

0.085 

0.084 

0.083 

0.082 

0.126 

0.123 

0.121 

0.119 

0.117 
10

LTA Equations

LTAacute = ECAacute * ECA multiplieracute99 (from Table 1 or as calculated above)

LTAchronic = ECAchronic * ECA multiplierchronic99 (from Table 1 or as calculated above)

 Step 4: Select the lowest (most limiting) of the LTAs for the pollutant derived in Step 3. 

Step 5: Calculate water quality-based effluent limitations (an *average monthly effluent 

limitation, AMEL, and a *maximum daily effluent limitation, MDEL) by multiplying the 

most limiting LTA (as selected in Step 4) with a factor (multiplier) that adjusts for the 

averaging periods and exceedance frequencies of the criteria/objectives and the effluent 

limitations, and the effluent monitoring frequency as follows: 

AMELaquatic life = LTA * AMEL multiplier95 (from Table 2 or as calculated below)

 MDELaquatic life = LTA * MDEL multiplier99 (from Table 2 or as calculated below)

 

 The AMEL and MDEL multipliers shall be calculated as described below, or shall be found 

in Table 2 using the previously calculated CV and the monthly sampling frequency (n) of the 

pollutant in the effluent. If the sampling frequency is four times a month or less, n shall be 

set equal to 4. For this method only, maximum daily effluent limitations shall be used for 

publicly-owned treatment works (POTWs) in place of average weekly limitations. 

AMEL and MDEL Multipliers

AMEL multiplier95 = e(zσn – 0.5σn

2

)

Where σn = [ln(CV2

/n + 1)]0.5

σn

2

 = ln(CV2/n + 1) 

 z = 1.645 for 95th percentile probability basis 

 n = number of samples per month 

MDEL multiplier99 = e(zσ – 0.5σ

2

)

Where σ = [ln(CV2

 + 1)]0.5

σ

2

 = ln(CV2 + 1) 

 z = 2.326 for 99th percentile probability basis 

Step 6: For the applicable human health criterion/objective, set the AMEL equal to the ECA

(from Step 2). 

AMELhuman health = ECA 

To calculate the MDEL for a human health criterion/objective, multiply the ECA by the ratio 

of the MDEL multiplier to the AMEL multiplier.
11

Table 2. Long-Term Average (LTA) Multipliers for Calculating 

 Effluent Limitations 

MDEL 

Multiplier 

AMEL Multiplier MDEL/AMEL Multiplier 

Coefficient 

of 

Variation 99th Percentile 

Occurrence 

Probability 

95th Percentile 

Occurrence Probability 

MDEL = 99th Percentile 

AMEL = 95th Percentile 

Occurrence Probability 

(CV) n = 4 n = 8 n = 30 n = 4 n = 8 n = 30 

0.1 

0.2 

0.3 

0.4 

0.5 

1.25 

1.55 

1.90 

2.27 

2.68 

1.08 

1.17 

1.26 

1.36 

1.45 

1.06 

1.12 

1.18 

1.25 

1.31 

1.03 

1.06 

1.09 

1.12 

1.16 

1.16 

1.33 

1.50 

1.67 

1.84 

1.18 

1.39 

1.60 

1.82 

2.04 

1.22 

1.46 

1.74 

2.02 

2.32 

0.6 

0.7 

0.8 

0.9 

1.0 

3.11 

3.56 

4.01 

4.46 

4.90 

1.55 

1.65 

1.75 

1.85 

1.95 

1.38 

1.45 

1.52 

1.59 

1.66 

1.19 

1.22 

1.26 

1.29 

1.33 

2.01 

2.16 

2.29 

2.41 

2.52 

2.25 

2.45 

2.64 

2.81 

2.96 

2.62 

2.91 

3.19 

3.45 

3.70 

1.1 

1.2 

1.3 

1.4 

1.5 

5.34 

5.76 

6.17 

6.56 

6.93 

2.04 

2.13 

2.23 

2.31 

2.40 

1.73 

1.80 

1.87 

1.94 

2.00 

1.36 

1.39 

1.43 

1.47 

1.50 

2.62 

2.70 

2.77 

2.83 

2.89 

3.09 

3.20 

3.30 

3.39 

3.46 

3.93 

4.13 

4.31 

4.47 

4.62 

1.6 

1.7 

1.8 

1.9 

2.0 

7.29 

7.63 

7.95 

8.26 

8.55 

2.48 

2.56 

2.64 

2.71 

2.78 

2.07 

2.14 

2.20 

2.27 

2.33 

1.54 

1.57 

1.61 

1.64 

1.68 

2.93 

2.98 

3.01 

3.05 

3.07 

3.52 

3.57 

3.61 

3.65 

3.67 

4.74 

4.85 

4.94 

5.02 

5.09 

Note: 

n = monthly sampling frequency of the effluent concentration data
12

Table 2. Continued

MDEL 

Multiplier 

AMEL Multiplier MDEL/AMEL Multiplier 

Coefficient 

of 

Variation 

99th Percentile 

Occurrence 

Probability 

95th Percentile 

Occurrence Probability 

MDEL = 99th Percentile 

AMEL = 95th Percentile 

Occurrence Probability 

(CV) n = 4 n = 8 n = 30 n = 4 n = 8 n = 30 

2.1 

2.2 

2.3 

2.4 

2.5 

8.83 

9.09 

9.34 

9.58 

9.81 

2.85 

2.91 

2.97 

3.03 

3.08 

2.39 

2.45 

2.50 

2.56 

2.61 

1.72 

1.75 

1.79 

1.82 

1.86 

3.10 

3.12 

3.15 

3.17 

3.18 

3.70 

3.72 

3.73 

3.74 

3.75 

5.14 

5.19 

5.22 

5.25 

5.27 

2.6 

2.7 

2.8 

2.9 

3.0 

10.0 

10.2 

10.4 

10.6 

10.8 

3.13 

3.18 

3.23 

3.27 

3.31 

2.67 

2.72 

2.77 

2.82 

2.86 

1.90 

1.93 

1.97 

2.00 

2.04 

3.20 

3.22 

3.23 

3.25 

3.26 

3.76 

3.76 

3.77 

3.77 

3.77 

5.29 

5.30 

5.30 

5.30 

5.30 

3.1 

3.2 

3.3 

3.4 

3.5 

11.0 

11.1 

11.3 

11.4 

11.6 

3.35 

3.38 

3.42 

3.45 

3.48 

2.91 

2.95 

2.99 

3.03 

3.07 

2.07 

2.11 

2.14 

2.17 

2.21 

3.27 

3.29 

3.30 

3.31 

3.32 

3.77 

3.77 

3.77 

3.77 

3.77 

5.29 

5.28 

5.27 

5.25 

5.24 

3.6 

3.7 

3.8 

3.9 

4.0 

11.7 

11.8 

11.9 

12.1 

12.16 

3.51 

3.53 

3.56 

3.58 

3.60 

3.10 

3.14 

3.17 

3.21 

3.24 

2.24 

2.27 

2.30 

2.34 

2.37 

3.33 

3.34 

3.35 

3.36 

3.37 

3.76 

3.76 

3.76 

3.76 

3.76 

5.22 

5.20 

5.18 

5.16 

5.14 

Note: 

n = monthly sampling frequency of the effluent concentration data.
13

MDEL/AMEL multiplier = MDEL multiplier99 ÷ AMEL multiplier95

MDELhuman health = ECA * MDEL/AMEL multiplier 

Step 7: Identify the lower of (1) the AMEL and MDEL calculated based on the aquatic life 

criteria/objectives, and (2) the AMEL and MDEL calculated based on the human health 

criterion/objective. 

C. Apply a *dynamic model, approved by the RWQCB, where sufficient effluent and receiving 

water data exist; or 

D. Establish effluent limitations that consider intake water pollutants according to section 1.4.4. 

The RWQCB shall impose more restrictive water quality-based effluent limitations (e.g., 

discharge prohibitions established in accordance with Water Code Section 13243) where 

necessary for the protection of beneficial uses or where otherwise required by law1

. Seasonal 

effluent limitations may be established where appropriate (such as in applying translators and 

mixing zones/dilution credits). Any significant change in effluent quantity or quality shall be 

cause for reevaluation of effluent limitations. 

Regardless of which method is used for deriving water quality-based effluent limitations, the 

calculated water quality-based effluent limitations shall be compared to the technology-based 

effluent limitations for the pollutant, and the most protective of the two types of limitations shall 

be included in the permit. 

Effluent limitations shall apply to the total effluent of a waste discharge at the end-of-pipe, 

except in the rare situations where it is impractical or infeasible (e.g., where the final discharge 

point is inaccessible, or the pollutants are so diluted by cooling water as to make monitoring 

impractical, or interferences among pollutants make analysis infeasible). In these cases, some 

effluent limitations and monitoring requirements for the discharge may be modified to apply to 

internal waste streams instead, provided that the permit fact sheet fully states the circumstances 

for allowing this to occur and the permit also contains the unmodified effluent limitations (see 

40 CFR 122.45(h), revised as of July 1, 1996). 

For pollutants that are so diluted by cooling water as to make monitoring impractical, 

effluent limitations for internal waste streams shall be based on the same averaging periods as 

the unmodified effluent limitations and shall be calculated as follows

 

1

For example, to implement the State and federal antidegradation policies, and the federal antibacksliding requirements.
14

IL = EL + (EL - CC) * CF/IF 

IL = EL + (EL - CC) * (EF - IF)/IF 

where IL = the limitation for the internal waste stream; 

 EL = the unmodified effluent limitation; 

 CC = the concentration of the pollutant in the cooling water; 

 CF = the cooling water flow, which is equal to the effluent flow minus the internal 

waste stream flow; 

 IF = the internal waste stream flow; and 

 EF = the effluent flow. 

These equations do not apply when intake water credits (as described in section 1.4.4) are being 

provided. 

 1.4.1 Translators for Metals and Selenium

To derive total recoverable effluent limitations for aquatic life metals and selenium 

criteria/objectives that are expressed in the dissolved form, a translator first must be applied to 

the criterion/objective to express it as total recoverable. The translator shall be the U.S. EPA 

conversion factor (see Appendix 3) that applies to the dissolved aquatic life metals criterion as 

specified in the CTR (i.e., the dissolved criterion/objective would be divided by the applicable 

U.S. EPA conversion factor to calculate a total recoverable criterion) unless: 

A. the discharger, in the permit application, (1) commits to (a) completing a defensible 

site-specific translator study and (b) proposing a dissolved to total recoverable translator to 

the RWQCB, and (2) describes the method(s) to be used in developing the translator; and 

B. the discharger, within a time period specified by the RWQCB not exceeding two years from 

the date of issuance/reissuance of the permit, submits to the RWQCB (1) the proposed 

translator, and (2) all data and calculations related to its derivation. 

Site-specific translators can be developed from field data by either direct determination of the 

fraction dissolved, or by development of a site-specific partition coefficient that relates the 

fraction dissolved to ambient background conditions such as pH, suspended load, or organic 

carbon. The fraction of metal that is dissolved in a water body can vary depending on when and 

where measurements are taken. A site-specific translator must (1) account for spatial and/or 

seasonal variability in areas of the water body that are affected by the discharger’s effluent and 

(2) protect against toxic effects during critical conditions. The translator shall be derived using 

the *median of data for translation of chronic criteria and the *90th percentile of observed data 

for translation of acute criteria. If systematic seasonal variation in the translator is demonstrated, 

seasonal effluent limitations may be justified. If a spatial gradient in the translator is 

demonstrated, the highest translator value should be used unless the permit allows for a mixing 

zone (in accordance with section 1.4.2), in which case measurements should be taken outside the 

mixing zone. The site-specific study plan (including sampling design) must be approved by the 

RWQCB, after consultation with the California Department of Fish and Game, prior to 

conducting the study. Translator studies may be conducted by one or more dischargers 

discharging to the same receiving water body, as described in the permit application, subject to 

approval by the RWQCB. The planning and undertaking of the study may follow the guidelines 

presented in Appendix 5, as applicable. 
15

Alternatively, the RWQCB may consider applying a previously approved site-specific translator 

or translator based on a study completed prior to the adoption of this Policy if the RWQCB 

believes the translator adequately reflects existing conditions (including spatial and/or seasonal 

variability) in the areas of the water body affected by the discharger’s effluent. 

While a translator study is being conducted, a final effluent limitation based on the applicable 

U.S. EPA conversion factor shall be included in the provisions of the permit and interim 

requirements shall be established (in accordance with section 2.2.2). An interim deadline to 

submit the results of the study shall be specified by the RWQCB, and shall not exceed two years 

from the date of issuance/reissuance of the permit. Once the translator is developed by the 

discharger(s) and approved by the RWQCB, the RWQCB shall reopen the permit and a new 

effluent limitation shall be calculated using a method described in section 1.4 after adjusting the 

dissolved metal or selenium criterion/objective by dividing it by the translator. In the event a 

translator study is not completed within the specified time, the U.S. EPA conversion factor-based 

effluent limitation in the provisions of the permit shall become effective as a default limitation. 

 1.4.2 Mixing Zones and Dilution Credits

With the exception of effluent limitations derived from TMDLs, in establishing and determining 

compliance with effluent limitations for applicable human health, acute aquatic life, or chronic 

aquatic life priority pollutant criteria/objectives or the toxicity objective for aquatic life 

protection in a RWQCB basin plan, the RWQCB may grant *mixing zones and *dilution credits 

to dischargers in accordance with the provisions of this section. To the extent permitted by 

applicable law, mixing zones may be considered for TMDL-derived effluent limitations. 

Effluent limitations based on a TMDL shall meet the mixing zone conditions specified in 

section 1.4.2.2.A. 

The applicable priority pollutant criteria and objectives are to be met throughout a water body 

except within any mixing zone granted by a RWQCB. The allowance of mixing zones is 

discretionary and shall be determined on a discharge-by-discharge basis. A RWQCB may 

consider allowing mixing zones and dilution credits only for discharges with a physically 

identifiable point of discharge that are regulated through an NPDES permit issued by the 

RWQCB. 

1.4.2.1 Dilution Credits

The dilution credit, D, is a numerical value associated with the mixing zone that accounts for the 

receiving water entrained into the discharge. The dilution credit is a value used in the 

calculation of effluent limitations (described in section 1.4). Dilution credits may be limited or 

denied on a pollutant-by-pollutant basis, which may result in a dilution credit for all, some, or no 

priority pollutants in a discharge. 

Before establishing a mixing zone and a dilution credit for a discharge, it must first be 

determined if, and how much (if any), receiving water is available to dilute the discharge. In 

determining the appropriate available receiving water flow, the RWQCBs may take into account 

actual and seasonal variations of the receiving water and the effluent. For example, a RWQCB 

may prohibit mixing zones during seasonal low flows and allow them during seasonal high 

flows. However, for year-round mixing zones, the mixing zone and dilution credit shall be 
16

determined using the parameters specified in Table 3. 

Table 3. Effluent and Receiving Water Flows for Calculating Dilution Ratios 

In calculating a dilution 

ratio for: 

Use the critical 

receiving water flow1

of: 

Use the discharged effluent 

flow of:

Acute aquatic life 

criteria/objectives 

 *1Q10 *maximum daily flow during 

period of discharge 

Chronic aquatic life 

criteria/objectives 

Chronic toxicity objective for 

aquatic life2

*7Q10 *four-day average of daily 

maximum flows during period of 

discharge 

Human health 

criteria/objectives 

 *harmonic mean *long-term arithmetic mean flow 

during period of discharge 

The approach to making a mixing zone determination also depends on whether a discharge is 

*completely-mixed or *incompletely-mixed with the receiving water as discussed below.

Completely Mixing Discharges

For completely-mixed discharges, as determined by the RWQCB and based on information 

provided by the discharger, the amount of receiving water available to dilute the effluent shall be 

determined by calculating the *dilution ratio (i.e., the critical receiving water flow divided by the 

effluent flow) using the appropriate flows in Table 3. In no case shall the RWQCB grant a 

dilution credit that is greater than the calculated dilution ratio. The dilution credit may be set 

equal to the dilution ratio only if the site-specific conditions concerning the discharge and the 

receiving water do not indicate that a smaller dilution credit is necessary to protect beneficial 

uses and meet the conditions of this Policy. If, however, dilution ratios that are calculated using 

the Table 3 parameters are inappropriate for use due to site-specific issues, the mixing zone and 

dilution credit shall be determined using site-specific information and procedures detailed for 

incompletely-mixed discharges. 

Incompletely-Mixed Discharges

Dilution credits and mixing zones for incompletely-mixed discharges shall be considered by the 

 

1

U.S. EPA’s *biologically-based receiving water flows may be used in place of these critical receiving water flows 

where sufficient data are available. 

2

These objectives are included in RWQCB basin plans and may address both chronic and acute toxicity to aquatic life. 

The flows in Table 3 apply to the chronic component of the objective. 
17

RWQCB only after the discharger has completed an independent mixing zone study and 

demonstrated to the satisfaction of the RWQCB that a dilution credit is appropriate. Mixing 

zone studies may include, but are not limited to, tracer studies, dye studies, modelling studies, 

and monitoring upstream and downstream of the discharge that characterize the extent of actual 

dilution. These studies may be conducted in accordance with the procedures outlined in 

Appendix 5. 

1.4.2.2 Mixing Zone Conditions

A mixing zone shall be as small as practicable. The following conditions must be met in 

allowing a mixing zone: 

 A. A mixing zone shall not: 

 (1) compromise the integrity of the entire water body; 

 (2) cause *acutely toxic conditions to aquatic life passing through the mixing zone; 

 (3) restrict the passage of aquatic life; 

 (4) adversely impact biologically sensitive or critical habitats, including, but not limited 

to, habitat of species listed under federal or State endangered species laws; 

 (5) produce undesirable or nuisance aquatic life; 

 (6) result in floating debris, oil, or scum; 

 (7) produce objectionable color, odor, taste, or turbidity; 

 (8) cause *objectionable bottom deposits; 

 (9) cause nuisance; 

(10) dominate the receiving water body or overlap a mixing zone from different outfalls; 

or 

(11) be allowed at or near any drinking water intake. A mixing zone is not a *source of 

drinking water. To the extent of any conflict between this determination and the 

Sources of Drinking Water Policy (SWRCB Resolution No. 88-63), this 

determination supersedes the provisions of that policy. 

B. The RWQCB shall deny or significantly limit a mixing zone and dilution credit as necessary 

to protect beneficial uses, meet the conditions of this Policy, or comply with other regulatory 

requirements. Such situations may exist based upon the quality of the discharge, hydraulics 

of the water body, or the overall discharge environment (including water column chemistry, 

organism health, and potential for bioaccumulation). For example, in determining the extent 

of or whether to allow a mixing zone and dilution credit, the RWQCB shall consider the 

presence of pollutants in the discharge that are *carcinogenic, *mutagenic, *teratogenic, 

*persistent, *bioaccumulative, or attractive to aquatic organisms. In another example, the 

RWQCB also shall consider, if necessary to protect the beneficial uses, the level of flushing 

in water bodies such as lakes, reservoirs, enclosed bays, estuaries, or other water body types 

where pollutants may not be readily flushed through the system. In the case of multiple 

mixing zones, proximity to other outfalls shall be carefully considered to protect the 

beneficial uses. 

If a RWQCB allows a mixing zone and dilution credit, the permit shall specify the method by 

which the mixing zone was derived, the dilution credit granted, and the point(s) in the 

receiving water where the applicable criteria/objectives must be met. The application for the 

permit shall include, to the extent feasible, the information needed by the RWQCB to make a 
18

determination on allowing a mixing zone, including the calculations for deriving the 

appropriate receiving water and effluent flows, and/or the results of a mixing zone study. If 

the results of the mixing zone study are unavailable by the time of permit 

issuance/reissuance, the RWQCB may establish interim requirements in accordance with 

section 2.2.2. 

 1.4.3 Ambient Background Concentrations

Ambient background concentration, B, of a priority pollutant in the receiving water body shall be 

calculated on a pollutant-by-pollutant basis and on a discharge-by-discharge or water body-bywater body basis at the RWQCB’s discretion. The ambient background concentration shall be 

the observed maximum ambient water column concentration in accordance with section 1.4.3.1 

or the *arithmetic mean of observed ambient water concentrations in accordance with 

section 1.4.3.2 where these sections are specifically referenced in this Policy (i.e., sections 1.3 

and 1.4). 

1.4.3.1 Ambient Background Concentration as an Observed Maximum

Step 1: Identify all available, applicable ambient background data for the pollutant in 

accordance with section 1.2. If possible, preference should be given to ambient water column 

concentrations measured immediately upstream or near the discharge, but not within an allowed 

mixing zone for the discharge. The RWQCB shall have discretion to consider if any samples are 

invalid for use as applicable data due to evidence that the sample has been erroneously reported 

or the sample is not representative of the ambient receiving water column that will mix with the 

discharge. For example, the RWQCB shall have discretion to consider samples to be invalid that 

have been taken during peak flows of significant storm events. 

Step 2: If all samples are below the reported detection limits, the ambient background 

concentration shall be set equal to the lowest of the individual reported detection limits. If any 

sample is reported with a detected concentration, as either measured or estimated by the 

laboratory, the ambient background concentration shall be set equal to the maximum of the 

individual reported measured or estimated concentrations. 

1.4.3.2 Ambient Background Concentration as an Arithmetic Mean

Step 1: Identify all available, applicable ambient background data for the pollutant in 

accordance with section 1.2. If possible, preference should be given to ambient water column 

concentrations measured immediately upstream or near the discharge, but not within an allowed 

mixing zone for the discharge. The RWQCB shall have discretion to consider if any samples are 

invalid for use as applicable data due to evidence that the sample has been erroneously reported 

or the sample is not representative of the ambient receiving water column that will mix with the 

discharge. 

Step 2: If all samples are below the reported detection limits, the ambient background 

concentration shall be set equal to the lowest of the individual reported detection limits. If any 

sample is reported with a detected concentration, as either measured or estimated by the 

laboratory, the ambient background concentration shall be set equal to the arithmetic mean of the 

individual reported measured or estimated concentrations. The arithmetic mean shall be 

calculated using the reported detection limits for samples that are reported below detection 
19

limits. 

 1.4.4 Intake Water Credits

A RWQCB may consider priority pollutants in intake water on a pollutant-by-pollutant and 

discharge-by-discharge basis when establishing water quality-based effluent limitations, 

provided that the discharger has demonstrated to the satisfaction of the RWQCB that the 

following conditions are met: 

(1) The observed maximum ambient background concentration, as determined in 

section 1.4.3.1, and the intake water concentration of the pollutant exceeds the most 

stringent applicable criterion/objective for that pollutant; 

(2) The intake water credits provided are consistent with any TMDL applicable to the 

discharge that has been approved by the RWQCB, SWRCB, and U.S. EPA; 

(3) The intake water is from the same water body as the receiving water body. The discharger 

may demonstrate this condition by showing that: 

(a) the ambient background concentration of the pollutant in the receiving water, 

excluding any amount of the pollutant in the facility’s discharge, is similar to that of 

the intake water; 

(b) there is a direct hydrological connection between the intake and discharge points; 

(c) the water quality characteristics are similar in the intake and receiving waters; and 

(d) the intake water pollutant would have reached the vicinity of the discharge point in 

the receiving water within a reasonable period of time and with the same effect had it 

not been diverted by the discharger. 

 The RWQCB may also consider other factors when determining whether the intake water 

is from the same water body as the receiving water body; 

(4) The facility does not alter the intake water pollutant chemically or physically in a manner 

that adversely affects water quality and beneficial uses; and 

(5) The timing and location of the discharge does not cause adverse effects on water quality 

and beneficial uses that would not occur if the intake water pollutant had been left in the 

receiving water body. 

Where the above conditions are met, the RWQCB may establish effluent limitations allowing the 

facility to discharge a mass and concentration of the intake water pollutant that is no greater than 

the mass and concentration found in the facility’s intake water. A discharger may add mass of 

the pollutant to its waste stream if an equal or greater mass is removed prior to discharge, so 

there is no net addition of the pollutant in the discharge compared to the intake water. Where 

proper operation and maintenance of a facility’s treatment system results in the removal of an 

intake water pollutant, the RWQCB may establish limitations that reflect the lower mass and 
20

 

concentration of the pollutant achieved by such treatment. 

Where intake water for a facility is provided by a municipal water supply system and the 

supplier provides treatment of the raw water that removes an intake water pollutant, the 

concentration of the intake water pollutant shall be determined at the point where the water 

enters the water supplier’s distribution system. 

Where a facility discharges pollutants from multiple sources that originate from the receiving 

water body and from other water bodies, the RWQCB may derive an effluent limitation 

reflecting the flow-weighted amount of each source of the pollutant provided that adequate 

monitoring to determine compliance can be established and is included in the permit. When 

calculating the flow-weighted effluent limitation, the pollutant from the receiving water body 

shall be assumed to have a concentration that is no greater than the concentration in the facility’s 

intake water; the same pollutant from other sources shall be assumed to have a concentration that 

is no greater than the most stringent applicable criterion/objective. 

The permit shall specify how compliance with mass- and concentration-based limitations for the 

intake water pollutant will be assessed. This may be done by basing the effluent limitation on 

ambient background concentration data. Alternatively, the RWQCB may determine compliance 

by simultaneously monitoring the pollutant concentrations in the intake water and in the effluent. 

This monitoring may be supplemented by monitoring internal waste streams or by a RWQCB 

evaluation of the use of *best management practices. 

2. DETERMINING COMPLIANCE WITH PRIORITY POLLUTANT 

CRITERIA/OBJECTIVES AND WATER QUALITY-BASED EFFLUENT 

LIMITATIONS FOR PRIORITY POLLUTANT CRITERIA/OBJECTIVES

Compliance with priority pollutant criteria/objectives and water quality-based effluent 

limitations established pursuant to section 1 shall be determined according to the following 

provisions for (1) compliance schedules (section 2.1), (2) interim requirements (section 2.2), (3) 

monitoring requirements (section 2.3), and (4) reporting requirements including compliance 

determinations (section 2.4). In determining compliance with effluent limitations based on 

intake water credits, only the monitoring requirements (section 2.3) and the reporting 

requirements (section 2.4) apply. In determining compliance with effluent limitations derived 

from TMDLs, only the compliance schedule provisions (section 2.1) apply. 

 2.1 Compliance Schedules

Based on an *existing discharger’s request and demonstration that it is *infeasible for the 

discharger to achieve immediate compliance with a CTR criterion3

, or with an effluent limitation 

based on a CTR criterion, the RWQCB may establish a compliance schedule in an NPDES 

permit. Compliance schedules shall not be allowed in permits for *new dischargers. 

A schedule of compliance shall include a series of required actions to be undertaken for the 

purpose of achieving a CTR criterion and/or effluent limitations based on a CTR criterion. 

These actions shall demonstrate reasonable progress toward the attainment of a CTR criterion 

and/or effluent limitations. The compliance schedule shall include a schedule for completion 

3

 CTR criteria, for purposes of this section, exclude NTR criteria. 
21

that reflects a realistic assessment of the shortest practicable time required to perform each task. 

The compliance schedule shall contain a final compliance date based on the shortest practicable 

time required to achieve compliance. The deadlines to complete each action in the compliance 

schedule shall be specified in the NPDES permit and shall be accompanied by interim 

requirements as described in section 2.2.1. When a compliance schedule exceeds one year from 

the date of permit issuance, interim limitations with specific compliance dates (as described in 

section 2.2.1) shall be included in the NPDES permit. If the final compliance date extends 

beyond the permit term, the final compliance date and supporting explanation shall be included 

in the permit findings. 

The discharger shall submit to the RWQCB the following justification before compliance 

schedules may be authorized in a permit: (a) documentation that diligent efforts have been made 

to quantify pollutant levels in the discharge and the sources of the pollutant in the waste stream, 

and the results of those efforts; (b) documentation of source control and/or pollution 

minimization efforts currently underway or completed; (c) a proposed schedule for additional or 

future source control measures, *pollutant minimization actions, or waste treatment (i.e., facility 

upgrades); and (d) a demonstration that the proposed schedule is as short as practicable. 

The schedule of compliance for point source dischargers in an NPDES permit shall be as short as 

practicable but in no case exceed the following: 

A. Up to five years from the date of permit issuance, reissuance, or modification to complete 

actions (such as pollutant minimization or facility upgrades) necessary to comply with CTR 

criterion-based effluent limitations that are derived with or without a TMDL. Such actions 

shall include the development and adoption of a site-specific objective, if appropriate, as 

provided in section 5.2. 

B. Up to 15 years from the effective date of this Policy to develop and adopt a TMDL, and 

accompanying Waste Load Allocations (WLAs) and Load Allocations (LAs), as described 

in section 2.1.1, below. 

In no case (unless an exception has been granted in accordance with section 5.3) shall a 

compliance schedule for these dischargers exceed, from the effective date of this Policy: 

(a) 10 years to establish and comply with CTR criterion-based effluent limitations; or 

(b) 20 years to develop and adopt a TMDL, and to establish and comply with WLAs derived 

from a TMDL for a CTR criterion (i.e., up to 15 years to complete the TMDL and up to five 

years to comply with a TMDL-derived effluent limitation). 

2.1.1 TMDL-Based Compliance Schedule 

The compliance schedule provisions for the development and adoption of a TMDL only apply 

when: (a) the discharger requests and demonstrates that it is *infeasible for the discharger to 

achieve immediate compliance with a CTR criterion, or with an effluent limitation based on a 

CTR criterion; and (b) the discharger has made appropriate commitments to support and expedite 

the development of the TMDL. In determining appropriate commitments, the RWQCB should 

consider the discharge’s contribution to current loadings and the discharger’s ability to 

participate in TMDL development. 

For *bioaccumulative priority pollutants for which the receiving water has been included on the 
22

CWA Section 303(d) list, the RWQCB should consider whether the mass loading of the 

bioaccumulative pollutant(s) should be limited to representative, current levels pending TMDL 

development in order to implement the applicable water quality standard. 

 2.2 Interim Requirements

If a compliance schedule is allowed (in accordance with section 2.1) or a schedule is allowed to 

collect and provide data needed to establish water quality-based effluent limitations for a CTR 

criterion (in accordance with provisions in section 1), interim requirements shall be included in 

an NPDES permit. 

2.2.1 Interim Requirements Under a Compliance Schedule 

If a compliance schedule is granted (in accordance with section 2.1), the RWQCB shall establish 

interim requirements and dates for their achievement in the NPDES permit. If the compliance 

schedule exceeds one year, the RWQCB shall establish interim numeric limitations for the 

priority pollutant in the permit and may also impose interim requirements to control the 

pollutant, such as *pollutant minimization and source control measures. Numeric interim 

limitations for the pollutant must be based on current treatment facility performance or on 

existing permit limitations, whichever is more stringent. If the existing permit limitations are 

more stringent, and the discharger is not in compliance with those limitations, the 

noncompliance under the existing permit must be addressed through appropriate enforcement 

action before the permit can be reissued, unless antibacksliding provisions are met. 

There shall be no more than one year between interim dates. The interim requirements shall 

state that the discharger must notify the RWQCB, in writing, no later than 14 days following 

each interim date, of its compliance or noncompliance with the interim requirements. 

If the compliance schedule is within the term of the permit, the final effluent limitations shall be 

included in the permit provisions. If the compliance schedule exceeds the length of the permit, 

the final effluent limitations shall be included in the permit findings. In the latter case, the 

findings shall include: (1) the water quality to be achieved; (2) the reason that a final water 

quality-based effluent limitation is not being incorporated into the permit as an enforceable 

limitation at this time; (3) a statement that it is the intent of the RWQCB to include, in a 

subsequent permit revision, the final water quality-based effluent limitation as an enforceable 

limitation (based either on the CTR criterion directly or on future regulatory developments, such 

as TMDL or site-specific objective development). The permit findings shall also state the 

appropriate enforcement actions that may be taken by the RWQCB if interim limitations and 

requirements are not met. 

2.2.2 Reserved

2.3 Monitoring Requirements

The RWQCB shall require dischargers to conduct self-monitoring programs and shall clearly 

state in all permits the objective and purpose of the monitoring. Furthermore, the RWQCB shall 

determine, and specify under the monitoring and reporting requirements, the sampling 

parameters, monitoring frequencies, locations, and analytical methods to be used. To evaluate 

compliance with effluent limitations, effluent and ambient monitoring should occur within a 
23

brief enough period to be able to evaluate the effect of the effluent on the ambient water quality. 

 All data shall be reported in accordance with section 2.4. Options for analytical methods are: 

(1) those methods listed in Appendix 4 and described in Tables 1A, 1B, 1C, 1D, and 1E of 

40 CFR 136.3 (revised as of May 14, 1999); or alternate test procedures for individual 

discharges that have been approved by the U.S. EPA Regional Administrator pursuant to 

40 CFR 136.4 (a) through (c), inclusive, and 40 CFR 136.5 (a) through (d), inclusive

(revised as of May 14, 1999); or 

(2) where no methods are specified for a given pollutant in the tables described in 

(1) above, methods approved by the SWRCB or RWQCB. 

Laboratories analyzing monitoring samples shall be certified by the Department of Health 

Services, in accordance with the provision of Water Code Section 13176, and must include 

quality assurance/quality control data with their reports. 

Dischargers are also encouraged to submit monitoring data in electronic formats approved by the 

SWRCB or RWQCB. 

Furthermore, it is the policy of the SWRCB that individual permit monitoring complement and 

be coordinated with water body, watershed, and regional monitoring programs to the extent 

practicable. 

2.4 Reporting Requirements 

The discharger shall submit to the RWQCB reports necessary to determine compliance with 

effluent limitations for priority pollutants in permits. The reports shall comply with the 

requirements of sections 2.4.1 through 2.4.4. 

 2.4.1 Reporting Levels 

The RWQCB shall require in the permit that the discharger shall report with each sample result: 

1. The Reporting Level (RL) (selected from the MLs listed in Appendix 4 in accordance with 

section 2.4.2 or established in accordance with section 2.4.3); and 

2. The laboratory’s current *Method Detection Limit (MDL), as determined by the procedure 

found in 40 CFR 136 (revised as of July 3, 1999). 

2.4.2 Selection and Use of Appropriate ML Value

Reporting Level Selection: When there is more than one ML value for a given substance, the 

RWQCB shall include as RLs, in the permit, all ML values, and their associated analytical 

methods, listed in Appendix 4 that are below the calculated effluent limitation. The discharger 

may select any one of those cited analytical methods for compliance determination. If no ML 

value is below the effluent limitation, then the RWQCB shall select as the RL, the lowest ML 

value, and its associated analytical method, listed in Appendix 4 for inclusion in the permit. 

ML Usage: The ML value in Appendix 4 represents the lowest quantifiable concentration in a 
24

sample based on the proper application of all method-based analytical procedures and the 

absence of any matrix interferences. Assuming that all method-specific analytical steps are 

followed, the ML value will also represent, after the appropriate application of method-specific 

factors, the lowest standard in the calibration curve for that specific analytical technique. 

Common analytical practices sometimes require different treatment of the sample relative to 

calibration standards. Some examples are given below: 

 Most Common 

Substance or Grouping Method-Specified Treatment Method-Specific Factor(s)

 Volatile organic No differential treatment 1 

 Semi-Volatile organic Samples concentrated by extraction 1000 

 Metals Samples diluted or concentrated 1⁄2, 2, and 4 

 Pesticides Samples concentrated by extraction 100 

Other factors may be applied to the ML depending on the specific sample preparation steps 

employed. For example, the treatment typically applied in cases where there are matrix-effects 

is to dilute the sample or sample aliquot by a factor of ten. In such cases, this additional factor 

must be applied in the computation of the reporting limit. Application of such factors will alter 

the RL (as described in section 2.4.1). 

Dischargers are to instruct laboratories to establish calibration standards so that the ML value (or 

its equivalent if there is differential treatment of samples relative to calibration standards) is the 

lowest calibration standard. At no time is the discharger to use analytical data derived from 

extrapolation beyond the lowest point of the calibration curve. The discharger’s laboratory(ies) 

may, as allowed for by the rules governing alterations to ML values in section 2.4.3 below, 

employ a calibration standard lower than the ML value in Appendix 4. 

2.4.3 Deviation from MLs Listed in Appendix 4 

The RWQCB, in consultation with the SWRCB’s Quality Assurance Program, shall establish an 

RL that is not contained an ML in Appendix 4 to be included in the discharger’s permit in any of 

the following situations: 

1. When the pollutant under consideration is not included in Appendix 4. 

2. When the discharger and the RWQCB agree to include in the permit a test method that is 

more sensitive than those specified in 40 CFR 136 (revised as of July 3, 1999). 

3. When a discharger agrees to use an RL that is lower than the MLs listed in Appendix 4. 

4. When a discharger demonstrates that the calibration standard matrix is sufficiently 

different from that used to establish the ML in Appendix 4 and proposes an appropriate 

ML for their matrix. 

5. When the discharger uses a method whose quantification practices are not consistent with 

the definition of an ML. Examples of such methods are the U.S. EPA-approved method 

1613 for dioxins and furans, method 1624 for volatile organic substances, and method 

1625 for semi-volatile organic substances. In such cases, the discharger, the RWQCB, 

and the SWRCB shall agree on a lowest quantifiable limit and that limit will substitute for 
25

the RL for reporting and compliance determination purposes. 
26

2.4.4 Reporting Protocols

The discharger shall report the results of analytical determinations for the presence of chemical 

constituents in a sample using the following reporting protocols: 

1. Sample results greater than or equal to the RL shall be reported as measured by the 

laboratory (i.e., the measured chemical concentration in the sample). 

2. Sample results less than the RL, but greater than or equal to the laboratory’s MDL, shall be 

reported as “Detected, but Not Quantified,” or DNQ. The *estimated chemical 

concentration of the sample shall also be reported. 

For the purposes of data collection, the laboratory shall write the estimated chemical 

concentration next to DNQ as well as the words “Estimated Concentration” (may be 

shortened to “Est. Conc.”). The laboratory may, if such information is available, include 

numerical estimates of the data quality for the reported result. Numerical estimates of data 

quality may be percent accuracy (+ a percentage of the reported value), numerical ranges 

(low to high), or any other means considered appropriate by the laboratory.

3. Sample results less than the laboratory’s MDL shall be reported as “Not Detected,” or ND. 

2.4.5 Compliance Determination 

Compliance with effluent limitations shall be determined as follows: 

1. Dischargers shall be deemed out of compliance with an effluent limitation, if the 

concentration of the priority pollutant in the monitoring sample is greater than the effluent 

limitation and greater than or equal to the RL. 

2. Dischargers shall be required to conduct a Pollutant Minimization Program (PMP) in 

accordance with section 2.4.5.1 when there is evidence (e.g., sample results reported as 

DNQ when the effluent limitation is less than the MDL, sample results from analytical 

methods more sensitive than those methods included in the permit in accordance with 

sections 2.4.2 or 2.4.3 above, presence of whole effluent toxicity, health advisories for fish 

consumption, results of benthic or aquatic organism tissue sampling) that the priority 

pollutant is present in the effluent above an effluent limitation and either: 

a. A sample result is reported as DNQ and the effluent limitation is less than the RL; or 

b. A sample result is reported as ND and the effluent limitation is less than the MDL. 

RWQCBs may include special provisions in the permit to require the gathering of evidence 

to determine whether the constituent of concern is present in the effluent at levels above a 

calculated effluent limitation. 

When determining compliance with an AMEL and more than one sample result is available in a 

month, the discharger shall compute the arithmetic mean unless the data set contains one or more 

reported determinations of DNQ or ND. In those cases, the discharger shall compute the median 
27

in place of the arithmetic mean in accordance with the following procedure: 

1. The data set shall be ranked from low to high, reported ND determinations lowest, DNQ 

determinations next, followed by quantified values (if any). The order of the individual ND 

or DNQ determinations is unimportant. 

2. The median value of the data set shall be determined. If the data set has an odd number of 

data points, then the median is the middle value. If the data set has an even number of data 

points, then the median is the average of the two values around the middle unless one or 

both of the points are ND or DNQ, in which case the median value shall be the lower of the 

two data points where DNQ is lower than a value and ND is lower than DNQ. 

If a sample result, or the arithmetic mean or median of multiple sample results, is below the RL, 

and there is evidence that the priority pollutant is present in the effluent above an effluent 

limitation and the discharger conducts a PMP (as described in section 2.4.5.1), the discharger 

shall not be deemed out of compliance. 

2.4.5.1 Pollutant Minimization Program

The goal of the PMP shall be to reduce all potential sources of a priority pollutant(s) through 

*pollutant minimization (control) strategies, including *pollution prevention measures as 

appropriate,4

 to maintain the effluent concentration at or below the water quality-based effluent 

limitation. The RWQCB may consider cost-effectiveness when establishing the requirements of 

a PMP. The program shall include, but not be limited to, the following actions and submittals 

acceptable to the RWQCB: 

1. An annual review and semi-annual monitoring of potential sources of the reportable priority 

pollutant(s), which may include fish tissue monitoring and other bio-uptake sampling; 

2. Quarterly monitoring for the reportable priority pollutant(s) in the influent to the wastewater 

treatment system; 

3. Submittal of a control strategy designed to proceed toward the goal of maintaining 

concentrations of the reportable priority pollutant(s) in the effluent at or below the effluent 

limitation; 

4. Implementation of appropriate cost-effective control measures for the reportable priority 

pollutant(s), consistent with the control strategy; and 

5. An annual status report that shall be sent to the RWQCB including: 

 a. All PMP monitoring results for the previous year; 

 b. A list of potential sources of the reportable priority pollutant(s); 

c. A summary of all actions undertaken pursuant to the control strategy; and 

 

4

 Pollution prevention measures may be particularly appropriate for persistent bioaccumulative priority pollutants where 

there is evidence that beneficial uses are being impacted. 
28

d. A description of actions to be taken in the following year. 

The permit shall contain a reopener clause authorizing modifications, or revocation and 

reissuance of the permit, as a result of the detection of a reportable priority pollutant generated 

by special conditions included in the permit. These special conditions in the permit may be, but 

are not limited to, fish tissue sampling, whole effluent toxicity tests, monitoring requirements on 

internal waste stream(s), and monitoring for surrogate parameters. Additional requirements may 

be included in the permit as a result of the special condition monitoring data. 

The completion and implementation of a pollution prevention plan, required pursuant to Water 

Code Section 13263.3(d), shall be considered to fulfill the PMP requirements of this section. 

3. 2,3,7,8-TCDD EQUIVALENTS

The CTR includes criteria for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). In addition 

to this compound, there are many congeners of chlorinated dibenzodioxins (2,3,7,8-CDDs) and 

chlorinated dibenzofurans (2,3,7,8-CDFs) that exhibit toxic effects similar to those of 2,3,7,8-

TCDD. The U.S. EPA has published toxic equivalency factors (TEFs) for 17 of the congeners. 

The TEFs express the relative toxicities of the congeners compared to 2,3,7,8-TCDD (whose 

TEF equals 1.0). In June 1997, participants in a World Health Organization (WHO) expert 

meeting revised TEF values for 1,2,3,7,8-PentaCDD, OctaCDD, and OctaCDF. The current 

TEFs for the 17 congeners, which include the three revised values, are shown in Table 4: 

Table 4. Toxic Equivalency Factors (TEFs) for 2,3,7,8-TCDD Equivalents 

 Congener TEF 

2,3,7,8-TetraCDD 1 

1,2,3,7,8-PentaCDD 1.0 

1,2,3,4,7,8-HexaCDD 0.1 

1,2,3,6,7,8-HexaCDD 0.1 

1,2,3,7,8,9-HexaCDD 0.1 

1,2,3,4,6,7,8-HeptaCDD 0.01 

OctaCDD 0.0001 

2,3,7,8-TetraCDF 0.1 

1,2,3,7,8-PentaCDF 0.05 

2,3,4,7,8-PentaCDF 0.5 

1,2,3,4,7,8-HexaCDF 0.1 

1,2,3,6,7,8-HexaCDF 0.1 

1,2,3,7,8,9-HexaCDF 0.1 

2,3,4,6,7,8-HexaCDF 0.1 

1,2,3,4,6,7,8-HeptaCDF 0.01 
1,2,3,4,7,8,9-HeptaCDF 0.01

OctaCDF 0.0001

_________________ 

TEF Reference: Van den Berg, M., et al. (22 additional authors). 1998. Toxic Equivalency Factors (TEFs) for PCBs, 

PCDDs, PCDFs, for humans and wildlife. Environmental Health Perspectives 106(12):775-792. 

Whether or not an effluent limitation is required for 2,3,7,8-TCDD in accordance with 

section 1.3 of this Policy, each RWQCB shall require (as described below) major and minor 

POTW and industrial dischargers in its region to conduct effluent monitoring for the 2,3,7,8-

TCDD congeners listed above. The purpose of the monitoring is to assess the presence and 

amounts of the congeners being discharged to inland surface waters, enclosed bays, and estuaries 

for the development of a strategy to control these chemicals in a future multi-media approach. 

Within one year of the effective date of this Policy, each RWQCB shall either (1) amend the 

NPDES permits, or (2) send a written request for the information pursuant to California Water 

Code Section 13267 or 13383, for NPDES permittees in their respective regions, requiring, for a 

period of three consecutive years from the date the permit is amended or the request is sent, that: 

(1) each major POTW and major industrial discharger monitor its effluent for the presence of the 

17 congeners once during dry weather and once during wet weather each of the three years; and 

(2) each minor POTW and minor industrial discharger monitor its effluent for the presence of the 

17 congeners once during dry weather and once during wet weather for one year during the 

three-year period. 

The RWQCB should coordinate this region-wide monitoring to provide data that are consistent 

with the purpose of the provisions of this section to the extent possible. The RWQCB shall 

encourage public and private dischargers, and local governments, to develop a coordinated, 

cooperative regional monitoring program to gather this information. 

The RWQCB shall require the discharger to report for each congener the analytical results of the 

effluent monitoring, including the quantifiable limit5

 and the MDL, and the measured or 

estimated concentration. In addition, the RWQCB shall require the discharger to multiply each 

measured or estimated congener concentration by its respective TEF value (presented above) and 

report the sum of these values. This information shall be submitted to the RWQCB as part of the 

discharger’s self-monitoring reports, in accordance with section 2.3. The RWQCB shall, 

subsequently, submit the information to the SWRCB. 

Based on the monitoring results, the RWQCB may, at its discretion, increase the monitoring 

requirement (e.g., increase sampling frequency) to further investigate frequent or significant 

detections of any congener. At the conclusion of the three-year monitoring period, the SWRCB 

and RWQCBs will assess the data (a total of six samples each from major POTWs and industrial 

dischargers, and a total of two samples each from minor POTWs and industrial dischargers), and 

determine whether further monitoring is necessary. 

 

5

 As determined by the procedure found in section 2.4.3, number 5. 

29
30

4. TOXICITY CONTROL PROVISIONS

This section establishes minimum toxicity control requirements for implementing the narrative 

toxicity objectives for aquatic life protection in RWQCB basin plans. These provisions are 

intended to supplement basin plan requirements and do not supersede existing RWQCB toxicity 

requirements. 

Water Quality-Based Toxicity Control

A chronic toxicity effluent limitation is required in permits for all discharges that will cause, 

have reasonable potential to cause, or contribute to chronic toxicity in receiving waters. 

To determine compliance with the chronic aquatic life toxicity objective in a RWQCB basin 

plan, or an effluent limitation based on the objective, the RWQCB shall require, in a permit or 

other appropriate order, the use of short-term chronic toxicity tests. At least three test species 

with approved test protocols shall be used to measure compliance with the toxicity objective. If 

possible, the test species shall include a vertebrate, an invertebrate, and an aquatic plant. After a 

screening period, monitoring may be reduced to the most sensitive species. Dilution and control 

waters should be obtained from an area unaffected by the discharge in the receiving waters. For 

rivers and streams, dilution water should be obtained immediately upstream of the wastewater 

outfall. Standard dilution water can be used if the above sources exhibit toxicity or if approved 

by the RWQCB. The sensitivity of the test organisms to a reference toxicant shall be determined 

concurrently with each bioassay and reported with the test results. 

The tests contained in Appendix II, "Chapter IV. Compliance With Toxicity Limitations and 

Objectives", of the California Ocean Plan (amended March 20, 1997 and effective July 23, 1997) 

are incorporated by reference and one or more of these tests shall be used to measure toxicity in 

salt water. This incorporation-by-reference is prospective, including future changes to the 

incorporated provisions as the changes take effect. One or more of the tests in Table 5 shall be 

used to measure chronic toxicity in fresh water. 

 

Table 5. Short-term Methods for Estimating Chronic Toxicity-Fresh Water 

Species Effect Test duration (days)

 fathead minnow larval survival; 7 

 (Pimephales promelas) growth 

 water flea (Ceriodaphnia dubia) survival; number 6 to 8 

 of young 

 alga (Selenastrum capricornutum) growth rate 4

 

Toxicity Test Reference: U.S. EPA. 1994. Short-term methods for estimating the chronic toxicity of effluents and 

receiving waters to freshwater organisms. Third edition. U.S. EPA Environmental Monitoring Systems Laboratory, 

Cincinnati, Ohio. EPA/600/4-91-002.
31

Toxicity Reduction Requirements

If a discharge causes or contributes to chronic toxicity in a receiving water body, a *toxicity 

reduction evaluation (TRE) is required. Where multiple dischargers to the same water body are 

required to conduct TREs, the TREs may be coordinated with the approval of the RWQCB. The 

TRE shall include all reasonable steps to identify the source(s) of toxicity. Once the source of 

toxicity is identified, the discharger shall take all reasonable steps necessary to eliminate 

toxicity. 

The following shall be incorporated into permits: (1) a requirement to conduct a TRE if repeated 

tests reveal toxicity as a result of the waste discharge; (2) a provision requiring a discharger to 

take all reasonable steps to control toxicity once the source of toxicity is identified; and (3) a 

statement that failure to conduct required toxicity tests or a TRE within a designated period shall 

result in the establishment of effluent limitations for chronic toxicity in a permit or appropriate 

enforcement action. 

5. SPECIAL PROVISIONS

The following sections include provisions that address certain discharges and factors that could 

affect the application of other provisions in this Policy. They include: (1) nonpoint source 

discharges (section 5.1); (2) site-specific objectives (section 5.2); and (3) exceptions to the 

Policy provisions (section 5.3). 

5.1 Nonpoint Source Discharges

It is the intent of the SWRCB, in adopting this Policy, that the implementation of the priority 

pollutant criteria/objectives and other requirements of this Policy for nonpoint source discharges 

shall be consistent with the State's “ Policy for the Implementation and Enforcement of the 

Nonpoint Source Pollution Control Program, 2004.” 

 5.2 Site-Specific Objectives

If a priority pollutant criterion or objective is inappropriate for a particular water body (i.e., it 

does not protect the beneficial uses or, based on site-specific conditions, a less stringent standard 

may be warranted), a water quality objective that differs from the applicable criterion or 

objective may be developed for the site. A RWQCB may develop site-specific objectives 

whenever it determines, in the exercise of its professional judgement, that it is appropriate to do 

so. Where a priority pollutant criterion or objective is not being attained in the water body, 

under certain circumstances, it may be more appropriate to pursue other approaches to achieve 

the applicable criterion or objective rather than develop a site-specific objective. These 

approaches include, but are not limited to, watershed management and development of TMDLs 

(see Appendix 5 and Appendix 6). The RWQCB may investigate, facilitate, or implement such 

approaches as appropriate. 

Regardless of an action taken by the RWQCB as described above, the RWQCB shall, at a public 

meeting, consider initiating the development of a site-specific objective under the following 

conditions: 
32

 

(1) A written request for a site-specific study, accompanied by a preliminary commitment to 

fund the study, subject to development of a workplan6, is filed with the RWQCB; and 

(2) Either: 

 (a) a priority pollutant criterion or objective is not achieved in the receiving water; or 

 (b) a holder of an NPDES permit demonstrates that they do not, or may not in the 

future, meet an existing or potential effluent limitation based on the priority 

pollutant criterion or objective; and 

(3) A demonstration that the discharger cannot be assured of achieving the criterion or 

objective and/or effluent limitation through reasonable treatment, source control, and 

*pollution prevention measures. This demonstration may include, but is not limited to, as 

determined by the RWQCB: 

 (a) an analysis of compliance and consistency with all relevant federal and State plans, 

policies, laws, and regulations; 

 (b) a thorough review of historical limits and compliance with those limits; 

 (c) a thorough review of current technology and technology-based limits; and 

 (d) an economic analysis of compliance with the priority pollutant criterion or objective 

of concern. 

During the period when site-specific objectives studies are being conducted, the RWQCB shall 

place effluent limitations based upon the applicable priority pollutant criteria or objectives into 

permits only in conjunction with an appropriate compliance schedule and interim requirements, 

as described in sections 2.1 and 2.2. 

A discharger subject to a schedule for compliance with a CTR criterion or CTR criterion-based 

effluent limitations, as described in section 2.1, may choose to, concurrently with the actions 

necessary to achieve compliance, conduct the studies necessary to support the development and 

adoption of a site-specific objective.7

Following adoption of a site-specific objective by the RWQCB, existing effluent limitations 

shall be replaced with effluent limitations (calculated as described in section 1.4) based on the 

adopted site-specific objective if the analysis in section 1.3 indicates that a limitation for the 

pollutant is required. In the event that, for reasons beyond the control of the discharger, a 

decision whether or not to adopt site-specific objectives has not been made by the RWQCB 

before the end of the compliance schedule, the compliance schedule shall be extended for an 

additional period to allow time for a decision whether or not to adopt the objective. However, in 

no event may a compliance schedule exceed the maximum time period allowed for compliance 

with the CTR criteria (as described in section 2.1) or priority pollutant objectives (as described 

in the basin plan, if applicable), unless an exception has been granted (in accordance with section 

5.3). 

6

 The elements presented under the “Special Studies Process” in Appendix 5 should be considered in developing the 

site-specific objectives workplan. 7

 A RWQCB may include a compliance schedule in a water quality standard based on a site-specific objective. Such a 

compliance schedule is separate and distinct from the compliance schedules established by this Policy. 
33

Development of Site-Specific Objectives

Water quality objectives shall be developed in a manner consistent with State and federal law 

and regulations. In accordance with the State’s Porter-Cologne Water Quality Control Act 

(Division 7 of the Water Code), objectives must provide for the reasonable protection of 

beneficial uses based on consideration of the factors listed in Water Code Section 13241. In 

accordance with federal law (CWA) and regulations (40 CFR 131.11, revised as of July 1, 1997), 

the objectives must be based on sound scientific rationale and protect the designated beneficial 

uses of the receiving water. 

The RWQCB shall use scientifically defensible methods appropriate to the situation to derive the 

objectives. Such methods may include U.S. EPA-approved methods (e.g., Water Effects Ratio 

[WER] procedure, recalculation procedure, a combination of recalculation and WER procedures, 

Resident Species Procedure), and/or other methods specified in the workplan. 

A site-specific objective adopted by the RWQCB may include a compliance schedule. However, 

if attainment of the potential objective(s) developed under the study is anticipated to be 

infeasible (as defined in 40 CFR 131.10(g), revised as of July 1, 1997), or if the RWQCB 

otherwise determines it is appropriate, a *use attainability analysis (UAA) may be conducted. 

The RWQCB shall conduct, with the participation of interested persons, as appropriate, the UAA 

in accordance with 40 CFR 131.10(j) (revised as of July 1, 1997). If the UAA shows that 

attainment of the designated beneficial use(s) is not feasible (pursuant to 40 CFR 131.10(g) 

(revised as of July 1, 1997), the RWQCB shall designate an alternative beneficial use or 

subcategory of use, and develop appropriate water quality objectives to protect the new use(s). 

Both the use(s) and the objective(s) established to protect it would be reevaluated during the 

triennial reviews of the State's water quality standards. 

 5.3 Exceptions

Categorical and case-by-case exceptions to this Policy may be granted pursuant to the provisions 

below. 

Categorical Exceptions

The RWQCB may, after compliance with the California Environmental Quality Act (CEQA), 

allow short-term or seasonal exceptions from meeting the priority pollutant criteria/objectives if 

determined to be necessary to implement control measures either: 

1. for resource or pest management (i.e., vector or weed control, pest eradication, or fishery 

management) conducted by *public entities or *mutual water companies to fulfill statutory 

requirements, including, but not limited to, those in the California Fish and Game, Food and 

Agriculture, Health and Safety, and Harbors and Navigation codes; or 

2. regarding drinking water conducted to fulfill statutory requirements under the federal Safe 

Drinking Water Act or the California Health and Safety Code. Such categorical exceptions 

may also be granted for draining water supply reservoirs, canals, and pipelines for 

maintenance, for draining municipal storm water conveyances for cleaning or maintenance, 

or for draining water treatment facilities for cleaning or maintenance. 
34

For each project, the discharger shall notify potentially affected public and governmental 

agencies. Also, the discharger shall submit to the Executive Officer of the appropriate RWQCB, 

for approval: 

 (1) A detailed description of the proposed action, including the proposed method of 

completing the action; 

 (2) A time schedule; 

 (3) A discharge and receiving water quality monitoring plan (before project initiation, 

during the project, and after project completion, with the appropriate quality 

assurance and quality control procedures); 

 (4) CEQA documentation; 

 (5) Contingency plans; 

 (6) Identification of alternate water supply (if needed); and 

 (7) Residual waste disposal plans. 

Additionally, upon completion of the project, the discharger shall provide certification by a 

qualified biologist that the receiving water beneficial uses have been restored. 

To prevent unnecessary delays in taking emergency actions or to expedite the approval process 

for expected or routine activities that fall under categorical exceptions, the discharger is advised 

to file with the appropriate RWQCB, in advance of seeking RWQCB approval, the information 

required in items (1)-(7) above, to the extent possible. 

Case-by-Case Exceptions

Where site-specific conditions in individual water bodies or watersheds differ sufficiently from 

statewide conditions and those differences cannot be addressed through other provisions of this 

Policy, the SWRCB may, in compliance with the CEQA, subsequent to a public hearing, and 

with the concurrence of the U.S. EPA, grant an exception to meeting a priority pollutant 

criterion/objective or any other provision of this Policy where the SWRCB determines: 

 1. The exception will not compromise protection of enclosed bay, estuarine, and inland 

surface waters for beneficial uses; and 

 2. The public interest will be served. 

An example of where a case-by-case exception would be appropriate is where it is necessary to 

accommodate wastewater reclamation or water conservation. 
 APPENDIX 1

Definition of Terms

ACUTELY TOXIC CONDITIONS, as used in the context of mixing zones, refers to lethality 

that occurs to mobile aquatic organisms that move or drift through the mixing zone. 

ARITHMETIC MEAN (μ), also called the average, is the sum of measured values divided by the 

number of samples. For ambient water concentrations, the arithmetic mean is calculated as 

follows: 

Arithmetic mean = μ = Σx / n where: Σx is the sum of the measured ambient water 

concentrations, and 

 n is the number of samples. 

AVERAGE MONTHLY EFFLUENT LIMITATION (AMEL) means the highest allowable 

average of daily pollutant discharges over a calendar month, calculated as the sum of all daily 

discharges measured during a calendar month divided by the number of measurements. 

BEST MANAGEMENT PRACTICES (BMPs) are methods, measures, or practices designed and 

selected to reduce or eliminate the discharge of pollutants to surface waters from point and 

nonpoint source discharges including storm water. BMPs include structural and non-structural 

controls, and operation and maintenance procedures, which can be applied before, during, and/or 

after pollution producing activities. 

BIOACCUMULATIVE pollutants are those substances taken up by an organism from its 

surrounding medium through gill membranes, epithelial tissue, or from food and subsequently 

concentrated and retained in the body of the organism. 

BIOLOGICALLY-BASED RECEIVING WATER FLOW refers to the method for determining 

receiving water flows developed by the U.S. EPA Office of Research and Development which 

directly uses the averaging periods and exceedance frequencies specified in the acute and 

chronic aquatic life criteria for individual pollutants (e.g., 1 day and 3 years for acute criteria, 

and 4 days and 3 years for the chronic criteria). Biologically-based flows can be calculated 

using the program DFLOW.

CARCINOGENIC pollutants are substances that are known to cause cancer in living organisms. 

COEFFICIENT OF VARIATION (CV) is a measure of the data variability and is calculated as 

the estimated standard deviation divided by the arithmetic mean of the observed values. 

COMPLETELY-MIXED DISCHARGE condition means not more than a 5 percent difference, 

accounting for analytical variability, in the concentration of a pollutant exists across a transect of

the water body at a point within two stream/river widths from the discharge point. 

APPENDIX 1 - 1 
DILUTION CREDIT is the amount of dilution granted to a discharge in the calculation of a 

water quality-based effluent limitation, based on the allowance of a specified mixing zone. It is 

calculated from the dilution ratio or determined through conducting a mixing zone study or 

modeling of the discharge and receiving water. 

DILUTION RATIO is the critical low flow of the upstream receiving water divided by the flow 

of the effluent discharged. 

DISCHARGER-SPECIFIC WER is a WER that is applied to individual pollutant limits in an 

NPDES permit issued to a particular permit holder. A discharger-specific WER applies only to 

the applicable limits in the discharger’s permit. Discharger-specific WERs are distinguished for 

WERs that are developed on a waterbody or watershed basis as part of a water quality standards 

action resulting in adoption of an SSO. 

DYNAMIC MODELS used for calculating effluent limitations predict the effects of receiving 

water and effluent flow and of concentration variability. The outputs of dynamic models can be 

used to base effluent limitations on probability estimates of receiving water concentrations rather 

than critical conditions (which are used in the steady-state model). The three dynamic modeling 

techniques recommended by the U.S. EPA for calculating effluent limitations are continuous 

simulation, Monte Carlo simulation, and lognormal probability modeling. 

EFFLUENT CONCENTRATION ALLOWANCE (ECA) is a value derived from the water 

quality criterion/objective, dilution credit, and ambient background concentration that is used, in 

conjunction with the coefficient of variation for the effluent monitoring data, to calculate a longterm average (LTA) discharge concentration. The ECA has the same meaning as waste load 

allocation (WLA) as used in U.S. EPA guidance (Technical Support Document For Water 

Quality-based Toxics Control, March 1991, second printing, EPA/505/2-90-001). 

ENCLOSED BAYS means indentations along the coast that enclose an area of oceanic water 

within distinct headlands or harbor works. Enclosed bays include all bays where the narrowest 

distance between the headlands or outermost harbor works is less than 75 percent of the greatest 

dimension of the enclosed portion of the bay. Enclosed bays include, but are not limited to, 

Humboldt Bay, Bodega Harbor, Tomales Bay, Drake’s Estero, San Francisco Bay, Morro Bay, 

Los Angeles-Long Beach Harbor, Upper and Lower Newport Bay, Mission Bay, and 

San Diego Bay. Enclosed bays do not include inland surface waters or ocean waters. 

ESTIMATED CHEMICAL CONCENTRATION is the estimated chemical concentration that 

results from the confirmed detection of the substance by the analytical method below the ML 

value. 

ESTUARIES means waters, including coastal lagoons, located at the mouths of streams that 

serve as areas of mixing for fresh and ocean waters. Coastal lagoons and mouths of streams that 

are temporarily separated from the ocean by sandbars shall be considered estuaries. Estuarine 

waters shall be considered to extend from a bay or the open ocean to a point upstream where 

there is no significant mixing of fresh water and seawater. Estuarine waters included, but are not 

limited to, the Sacramento-San Joaquin Delta, as defined in Water Code Section 12220, 

APPENDIX 1 - 2 
Suisun Bay, Carquinez Strait downstream to the Carquinez Bridge, and appropriate areas of the 

Smith, Mad, Eel, Noyo, Russian, Klamath, San Diego, and Otay rivers. Estuaries do not include 

inland surface waters or ocean waters. 

EXISTING DISCHARGER means any discharger that is not a new discharger. An existing 

discharger includes an “increasing discharger” (i.e., an existing facility with treatment systems in 

place for its current discharge that is or will be expanding, upgrading, or modifying its existing 

permitted discharge after the effective date of this Policy). 

FOUR-DAY AVERAGE OF DAILY MAXIMUM FLOWS is the average of daily maximums

taken from the data set in four-day intervals. 

HARMONIC MEAN flows are expressed as Qhm = (n)/(Σ

n

i=1 1/xi), where xi = specific data 

values and n = number of data values. 

INCOMPLETELY-MIXED DISCHARGE is a discharge that contributes to a condition that does 

not meet the meaning of a completely-mixed discharge condition. 

INFEASIBLE means not capable of being accomplished in a successful manner within a 

reasonable period of time, taking into account economic, environmental, legal, social, and 

technological factors. 

INLAND SURFACE WATERS are all surface waters of the State that do not include the ocean, 

enclosed bays, or estuaries. 

LOAD ALLOCATION (LA) is the portion of a receiving water's total maximum daily load that 

is allocated to one of its nonpoint sources of pollution or to natural background sources. 

LONG-TERM ARITHMETIC MEAN FLOW is at least two years of flow data used in 

calculating an arithmetic mean as defined in this appendix. 

MAXIMUM DAILY FLOW is the maximum flow sample of all samples collected in a calendar 

day. 

MAXIMUM DAILY EFFLUENT LIMITATION (MDEL) means the highest allowable daily 

discharge of a pollutant, over a calendar day (or 24-hour period). For pollutants with limitations 

expressed in units of mass, the daily discharge is calculated as the total mass of the pollutant 

discharged over the day. For pollutants with limitations expressed in other units of 

measurement, the daily discharge is calculated as the arithmetic mean measurement of the 

pollutant over the day. 

MEDIAN is the middle measurement in a set of data. The median of a set of data is found by 

first arranging the measurements in order of magnitude (either increasing or decreasing order). If 

the number of measurements (n) is odd, then the median = X(n+1)/2. If n is even, then the median 

= (Xn/2 + X(n/2)+1)/2 (i.e., the midpoint between the n/2 and n/2+1). 

APPENDIX 1 - 3 
METHOD DETECTION LIMIT (MDL) is the minimum concentration of a substance that can 

be measured and reported with 99 percent confidence that the analyte concentration is greater 

than zero, as defined in 40 CFR 136, Appendix B, revised as of May 14, 1999. 

MINIMUM LEVEL (ML) is the concentration at which the entire analytical system must give a 

recognizable signal and acceptable calibration point. The ML is the concentration in a sample 

that is equivalent to the concentration of the lowest calibration standard analyzed by a specific 

analytical procedure, assuming that all the method specified sample weights, volumes, and 

processing steps have been followed. 

MIXING ZONE is a limited volume of receiving water that is allocated for mixing with a 

wastewater discharge where water quality criteria can be exceeded without causing adverse 

effects to the overall water body. 

MUTAGENIC pollutants are substances that are known to cause a mutation (i.e., change in a 

gene or chromosome) in living organisms. 

MUTUAL WATER COMPANY is defined in the Public Utilities Code, section 2725 as: “any 

private corporation or association organized for the purpose of delivering water to its 

stockholders and members at cost, including use of works for conserving, treating and reclaiming 

water”. 

NEW DISCHARGER includes any building, structure, facility, or installation from which there 

is, or may be, a discharge of pollutants, the construction of which commenced after the effective 

date of this Policy. 

OBJECTIONABLE BOTTOM DEPOSITS are an accumulation of materials or substances on or 

near the bottom of a water body, which creates conditions that adversely impact aquatic life, 

human health, beneficial uses, or aesthetics. These conditions include, but are not limited to, the 

accumulation of pollutants in the sediments and other conditions that result in harm to benthic 

organisms, production of food chain organisms, or fish egg development. The presence of such 

deposits shall be determined by RWQCB(s) on a case-by-case basis. 

OCEAN WATERS are the territorial marine waters of the State as defined by California law to 

the extent these waters are outside of enclosed bays, estuaries, and coastal lagoons. Discharges 

to ocean waters are regulated in accordance with the SWRCB’s California Ocean Plan. 

PERSISTENT pollutants are substances for which degradation or decomposition in the 

environment is nonexistent or very slow. 

POLLUTANT MINIMIZATION means waste minimization and pollution prevention actions 

that include, but are not limited to, product substitution, waste stream recycling, alternative 

waste management methods, and education of the public and businesses. 

POLLUTION PREVENTION means any action that causes a net reduction in the use or 

generation of a hazardous substance or other pollutant that is discharged into water and includes, 

APPENDIX 1 - 4 
but is not limited to, input change, operational improvement, production process change, and 

product reformulation (as defined in Water Code Section 13263.3). Pollution prevention does 

not include actions that merely shift a pollutant in wastewater from one environmental medium

to another environmental medium, unless clear environmental benefits of such an approach are 

identified to the satisfaction of the SWRCB or RWQCB. 

PROCESS OPTIMIZATION means minor changes to the existing facility and treatment plant 

operations that optimize the effectiveness of the existing treatment processes. 

PUBLIC ENTITY includes the federal government or a state, county, city and county, city, 

district, public authority, or public agency. 

SOURCE OF DRINKING WATER is any water designated as municipal or domestic supply 

(MUN) in a RWQCB basin plan. 

STANDARD DEVIATION (σ) is a measure of variability that is calculated as follows: 

 σ = (∑[(x - μ)

2

]/(n – 1))0.5

where: 

x is the observed value; 

μ is the arithmetic mean of the observed values; and 

n is the number of samples. 

TERATOGENIC pollutants are substances that are known to cause structural abnormalities or 

birth defects in living organisms. 

TOXICITY REDUCTION EVALUATION (TRE) is a study conducted in a step-wise process 

designed to identify the causative agents of effluent or ambient toxicity, isolate the sources of 

toxicity, evaluate the effectiveness of toxicity control options, and then confirm the reduction in 

toxicity. The first steps of the TRE consist of the collection of data relevant to the toxicity, 

including additional toxicity testing, and an evaluation of facility operations and maintenance 

practices, and best management practices. A Toxicity Identification Evaluation (TIE) may be 

required as part of the TRE, if appropriate. (A TIE is a set of procedures to identify the specific 

chemical(s) responsible for toxicity. These procedures are performed in three phases 

(characterization, identification, and confirmation) using aquatic organism toxicity tests.) 

USE ATTAINABILITY ANALYSIS is a structured scientific assessment of the factors affecting 

the attainment of the use which may include physical, chemical, biological and economic factors 

as described in 40 CFR 131.10(g) (40 CFR 131.3, revised as of July 1, 1997). 

WATER-EFFECT RATIO (WER) is an appropriate measure of the toxicity of a material 

obtained in a site water divided by the same measure of the toxicity of the same material 

obtained simultaneously in a laboratory dilution water. 

1Q10 is the lowest flow that occurs for one day with a statistical frequency of once every 

10 years. 

APPENDIX 1 - 5 
7Q10 is the average low flow that occurs for seven consecutive days with a statistical frequency 

of once every 10 years. 

90th PERCENTILE OF OBSERVED DATA is the measurement in the ordered set of data 

(lowest to highest) where 90 percent of the reported measurements are less than or equal to that 

value. 

APPENDIX 1 - 6 
APPENDIX 2

Determination of Pollutants Requiring Water Quality-Based 

Effluent Limitations 

Identify C

(1)

Is Effluent 

Data Avail?

(2)

Was 

Pollutant Detected

In Effluent? (3) 

All

DLs>C?

(3)

MEC=

Sample Max

(3)

MEC=

Min (DL)

(3)

Is

MEC>=C?

(4)

Is Ambient

Background

Data Avail?

(5)

B=Maximum

Background

Concentration

(5)

Is B>C?

(6)

With All

Non-Detects

(6)

With Any

Effluent

Detects (6)

Any

Additional

Info?

(7)

Effluent 

Limit

Is Required

Effluent 

Limit Is

NOT Required

Additional

Monitoring

Required (8)

Any

Additional

Info? (7)

Yes

No

No

Adjust MEC

Yes

Yes

No

Yes

No Yes

Adjust B

BPJ

No

or

No

Insuff Info

Yes

APPENDIX 2 - 1 
APPENDIX 3 

U.S. Environmental Protection Agency Conversion Factors 

Metal

Conversion 

Factor (CF) 

for 

Freshwater 

Acute Criteria

CF for 

Freshwater 

Chronic Criteria

CF for 

Saltwater 

Acute Criteria

CF(a) for 

Saltwater 

Chronic 

Criteria

Antimony (d) (d) (d) (d)

Arsenic 1.000 1.000 1.000 1.000

Beryllium (d) (d) (d) (d)

Cadmium (b) 0.944 0.909 0.994 0.994

Chromium (III) 0.316 0.860 (d) (d) 

Chromium (VI) 0.982 0.962 0.993 0.993

Copper 0.960 0.960 0.83 0.83

Lead (b) 0.791 0.791 0.951 0.951

Mercury 0.85 0.85 0.85 0.85

Nickel 0.998 0.997 0.990 0.990

Selenium (c) (c) 0.998 0.998

Silver 0.85 (d) 0.85 (d)

Thallium (d) (d) (d) (d)

Zinc 0.978 0.986 0.946 0.946

Footnotes:

(a) Conversion Factors for chronic marine criteria are not currently available. Conversion 

Factors for acute marine criteria have been used for both acute and chronic marine 

criteria. 

(b) Conversion Factors for these pollutants are hardness dependent. CFs are based on a 

hardness of 100 mg/l as calcium carbonate (CaCO3). Other hardness can be used; CFs 

should be recalculated using the following equations: 

Cadmium: Acute: CF = 1.136672 - [(ln {hardness})(0.041838)] 

Cadmium: Chronic: CF = 1.101672 - [(ln {hardness})(0.041838)] 

Lead: Acute and Chronic: CF = 1.46203 - [ln {hardness})(0.145712)] 

(c) Bioaccumulative compound and inappropriate to adjust to percent dissolved. 

(d) U.S. EPA has not published an aquatic life criterion value. 

NOTE: The term “Conversion Factor” represents the recommended conversion factor for 

converting a metal criterion expressed as the total recoverable fraction in the water column to a 

criterion expressed as the dissolved fraction in the water column. See “Office of Water Policy 

and Technical Guidance on Interpretation and Implementation of Aquatic Life Metals Criteria,” 

October 1, 1993, by Martha G. Prothro, Acting Assistant Administrator for Water, available 

from the Water Resource Center, USEPA, 401 M St. SW., mail code RC 4100, Washington, DC 

 20460; and 40 CFR §131.36(b)(1). 

Source: CTR (65 Fed. Register 31682-31719 (May 18, 2000), adding Section 131.38 to 

40 CFR). 

APPENDIX 3 - 1 
APPENDIX 4 

SWRCB Minimum Levels in ppb (μg/L)

The Minimum Levels (MLs) in this appendix are for use in reporting and compliance determination 

purposes in accordance with section 2.4 of this Policy. These MLs were derived from data for priority

pollutants provided by State certified analytical laboratories in 1997 and 1998. These MLs shall be used 

until new values are adopted by the SWRCB and become effective. The following tables (Tables 2a - 2d) 

present MLs for four major chemical groupings: volatile substances, semi-volatile substances, inorganics, 

and pesticides & PCBs. 

Table 2a - VOLATILE SUBSTANCES* GC GCMS 

1,1 Dichloroethane 0.5 1 

1,1 Dichloroethene 0.5 2 

1,1,1 Trichloroethane 0.5 2 

1,1,2 Trichloroethane 0.5 2 

1,1,2,2 Tetrachloroethane 0.5 1 

1,2 Dichlorobenzene (volatile) 0.5 2 

1,2 Dichloroethane 0.5 2 

1,2 Dichloropropane 0.5 1 

1,3 Dichlorobenzene (volatile) 0.5 2 

1,3 Dichloropropene (volatile) 0.5 2 

1,4 Dichlorobenzene (volatile) 0.5 2 

Acrolein 2.0 5

Acrylonitrile 2.0 2

Benzene 0.5 2

Bromoform 0.5 2

Bromomethane 1.0 2

Carbon Tetrachloride 0.5 2 

Chlorobenzene 0.5 2

Chlorodibromo-methane 0.5 2

Chloroethane 0.5 2

Chloroform 0.5 2

Chloromethane 0.5 2

Dichlorobromo-methane 0.5 2

Dichloromethane 0.5 2

Ethylbenzene 0.5 2

Tetrachloroethene 0.5 2

Toluene 0.5 2

trans-1,2 Dichloroethylene 0.5 1 

Trichloroethene 0.5 2

Vinyl Chloride 0.5 2 

*The normal method-specific factor for these substances is 1, therefore, the lowest standard concentration in the 

calibration curve is equal to the above ML value for each substance. 

APPENDIX 4 - 1 
Table 2b - SEMI-VOLATILE 

SUBSTANCES* 

GC GCMS LC COLOR 

1,2 Benzanthracene 10 5 

1,2 Dichlorobenzene (semivolatile) 2 2 

1,2 Diphenylhydrazine 1 

1,2,4 Trichlorobenzene 1 5 

1,3 Dichlorobenzene (semivolatile) 2 1 

1,4 Dichlorobenzene (semivolatile) 2 1 

2 Chlorophenol 2 5 

2,4 Dichlorophenol 1 5 

2,4 Dimethylphenol 1 2 

2,4 Dinitrophenol 5 5 

2,4 Dinitrotoluene 10 5 

2,4,6 Trichlorophenol 10 10 

2,6 Dinitrotoluene 5 

2- Nitrophenol 10 

2-Chloroethyl vinyl ether 1 1 2-Chloronaphthalene 10

3,3’ Dichlorobenzidine 5 

3,4 Benzofluoranthene 10 10 

4 Chloro-3-methylphenol 5 1 

4,6 Dinitro-2-methylphenol 10 5 

4- Nitrophenol 5 10 

4-Bromophenyl phenyl ether 10 5 

4-Chlorophenyl phenyl ether 5 Acenaphthene 1 1

0.5

Acenaphthylene100.2

Anthracene102

Benzidine5

Benzo(a) pyrene(3,4 Benzopyrene) 10 2 Benzo(g,h,i)perylene 5 0

.1

Benzo(k)fluoranthene102

bis 2-(1-Chloroethoxyl) methane 5 

bis(2-chloroethyl) ether 10 1 

bis(2-Chloroisopropyl) ether 10 2 

bis(2-Ethylhexyl) phthalate 10 5 

Butyl benzyl phthalate 10 10 Chrysene 10

5

di-n-Butyl phthalate 10 

di-n-Octyl phthalate 10 Dibenzo(a,h)-anthracene 10

0.1

Diethyl phthalate 10 2 

APPENDIX 4 - 2 
Table 2b - SEMI-VOLATILE GC GCMS LC COLOR 

SUBSTANCES* 

Dimethyl phthalate 10 2 

Fluoranthene 10 1 0.05

Fluorene 10 0.1

Hexachloro-cyclopentadiene 5 5

Hexachlorobenzene 5 1

Hexachlorobutadiene 5 1

Hexachloroethane 5 1

Indeno(1,2,3,cd)-pyrene 10 0.05

Isophorone 10 1

N-Nitroso diphenyl amine 10 1 

N-Nitroso-dimethyl amine 10 5 

N-Nitroso -di n-propyl amine 10 5 

Naphthalene 10 1 0.2

Nitrobenzene 10 1

Pentachlorophenol 1 5

Phenanthrene 5 0.05

Phenol ** 1 1 50

Pyrene 10 0.05

 * With the exception of phenol by colorimetric technique, the normal method-specific factor 

for these substances is 1000, therefore, the lowest standard concentration in the calibration 

curve is equal to the above ML value for each substance multiplied by 1000. 

** Phenol by colorimetric technique has a factor of 1. 

APPENDIX 4 - 3 
Table 2c –

INORGANICS* 

FAA GFAA ICP ICPMS SPGFAA HYDRIDE CVAA COLOR DCP

Antimony 10 5 50 0.5 5 0.5 1000

Arsenic 2 10 2 2 1 20 1000

Beryllium 20 0.5 2 0.5 1 1000

Cadmium 10 0.5 10 0.25 0.5 1000

Chromium (total) 50 2 10 0.5 1 1000

Chromium VI 5 10

Copper 25 5 10 0.5 2 1000

Cyanide 5

Lead 20 5 5 0.5 2 10,000

Mercury 0.5 0.2

Nickel 50 5 20 1 5 1000

Selenium 5 10 2 5 1 1000

Silver 10 1 10 0.25 2 1000

Thallium 10 2 10 1 5 1000

Zinc 20 20 1 10 1000

* The normal method-specific factor for these substances is 1, therefore, the lowest standard 

concentration in the calibration curve is equal to the above ML value for each substance. 

APPENDIX 4 - 4 
Table 2d - PESTICIDES – PCBs* GC 

4,4’-DDD 0.05

4,4’-DDE 0.05

4,4’-DDT 0.01

a-Endosulfan 0.02

a-Hexachloro-cyclohexane 0.01

Aldrin 0.005

b-Endosulfan 0.01

b-Hexachloro-cyclohexane 0.005

Chlordane 0.1

d-Hexachloro-cyclohexane 0.005

Dieldrin 0.01

Endosulfan Sulfate 0.05 

Endrin 0.01

Endrin Aldehyde 0.01 

Heptachlor 0.01

Heptachlor Epoxide 0.01 

Lindane(g-Hexachloro-cyclohexane) 0.02

PCB 1016 0.5 

PCB 1221 0.5 

PCB 1232 0.5 

PCB 1242 0.5 

PCB 1248 0.5 

PCB 1254 0.5 

PCB 1260 0.5 

Toxaphene 0.5

* The normal method-specific factor for these substances is 100, therefore, the lowest standard concentration in

the calibration curve is equal to the above ML value for each substance multiplied by 100. 

Techniques:

GC - Gas Chromatography

GCMS - Gas Chromatography/Mass Spectrometry

HRGCMS - High Resolution Gas Chromatography/Mass Spectrometry (i.e., EPA 1613, 1624, or 1625) 

LC - High Pressure Liquid Chromatography

FAA - Flame Atomic Absorption 

GFAA - Graphite Furnace Atomic Absorption 

HYDRIDE - Gaseous Hydride Atomic Absorption 

CVAA - Cold Vapor Atomic Absorption 

ICP - Inductively Coupled Plasma

ICPMS - Inductively Coupled Plasma/Mass Spectrometry

SPGFAA - Stabilized Platform Graphite Furnace Atomic Absorption (i.e., EPA 200.9) 

DCP - Direct Current Plasma

COLOR - Colorimetric

APPENDIX 4 - 5 
APPENDIX 5 

Special Studies 

Pre-Evaluation for Special Studies 

Decision Tree with Attached Narrative Discussion 

A special study is sometimes conducted as part of a regulatory process (standard setting and 

permit writing) and may be conducted as part of a collaborative watershed planning effort. 

Special studies can provide site-specific data that can assist in decision-making regarding water 

quality and beneficial use issues. 

Many water quality problems may be best addressed on a watershed or water body basis. The 

SWRCB believes that stakeholders should be able to develop flexible and innovative solutions 

for water quality problems in their watershed. For special studies conducted as part of a 

watershed management plan, the watershed management group should be involved in the design 

of the study, and study information should be provided back to the committee. Watershed or 

water body studies may gather data regarding topics such as: 

• TMDLs, WLAs, and LAs (see Appendix 6); 

• Regional ambient monitoring (regional ambient monitoring is the collection of scientific 

information regarding water quality and impacts to beneficial uses for a specified portion of, 

or an entire, watershed or water body); and 

• Contaminant fate and transport monitoring (contaminant fate and transport monitoring is the 

gathering of scientific information regarding how a specific pollutant[s] moves through the 

environment and how the pollutant[s] degrades or is otherwise transformed in the 

environment). 

These types of studies are useful to collect integrated, comprehensive, and systematic data 

regarding: 

• Baseline concentrations of toxic pollutants in the water and sediment; 

• Seasonal, annual, and long-term trends in water quality; 

• Causes and effects of water quality problems; 

• Effectiveness of a water quality control effort; 

APPENDIX 5 - 1 
• Greater certainty regarding existing monitoring data; etc. 

Any of the studies discussed below may be undertaken as part of a watershed approach to 

addressing regional water quality issues. Information collected as part of a watershed or water 

body study can be used as a way to define parameters (e.g., ambient background concentrations, 

mixing zones, etc.) related to the development of effluent limitations as part of the permitting 

process or to evaluate whether changes in water quality standards are appropriate. A watershed 

or water body approach is also useful to dischargers because information collected as a part of 

one effluent limitation or standard-setting study can be shared with other stakeholders in the 

same water body. 

Studies for Setting Effluent Limitations

Studies regarding establishing effluent limitations can be done as part of the permitting process. 

Such studies may be simpler and there may be fewer interested stakeholders than studies 

involving more than one discharger, or an entire water body or watershed. However, when such 

studies are undertaken individually, the discharger, the RWQCB, and other stakeholders do not 

gain the benefit of data collected from others in the watershed. 

Special studies may address topics such as the following: 

• Determining pollutants requiring effluent limitations (see section 1.3); 

• Metals translators (see section 1.4.1); or 

• Mixing zones (see section 1.4.2). 

Studies For Changes to Water Quality Standards

Establishing or modifying water quality standards (i.e., beneficial uses and water quality 

criteria/objectives) may involve complex and resource intensive studies. A detailed workplan 

will normally be needed because early planning and coordination with the RWQCB and 

U.S. EPA is critical to the development of a successful study. In addition, a workplan will 

normally be appropriate because there will be more stakeholder interest and involvement of 

other public agencies (e.g., Department of Fish and Game, U.S. Fish and Wildlife Service, etc.). 

Involvement in a watershed management planning effort would facilitate the sharing of 

information among stakeholders in the watershed, both in gathering information for the study 

and in sharing the results. Studies related to changes in water quality standards may address 

topics such as the following: 

• Site-specific objective studies (see section 5.2); and 

APPENDIX 5 - 2 
• Use attainability analysis (UAA) (see section 5.2). 

Pre-Evaluation

As a first step in determining whether and how to conduct a special study, the RWQCB or other 

stakeholders may want to evaluate whether it would be appropriate to address a water quality 

issue through a watershed management approach. To do that, the factors in the following 

flowchart may be considered: 

1. Is there a watershed management 

 group?a

 ↓ Yes 

2. Has a watershed management 

approach been developed?b

→→→→→ No GO TO start of Decision Treed

 if

water issue involves toxics. 

 ↓ Yes 

3. Are toxic pollutants part of the reason 

beneficial uses are impaired or water 

quality objectives are exceeded?c

→→→→→ No Issue is outside scope of this 

Policy. 

 ↓ Yes 

GO TO #9 in Decision Treed, or other 

point in Decision Tree as determined by 

stakeholders. 

 

 a Is there a committee of local interests in both the public and private sectors that are actively involved in the 

management of the watershed area?

 b Has a watershed management approach that identifies key issues, boundaries, objectives, and early actions 

been developed?

 c A study may be necessary to determine whether toxics are part of the cause of the impairment of beneficial

uses. This Policy applies only to the CTR and NTR criteria; and applicable chemical-specific basin plan 

objectives for priority toxic pollutants.

 d The decision tree is on page DRAFT APPENDIX 5 - 6.

APPENDIX 5 - 3 
The decision tree and associated narrative discussion in Appendix 5 are provided to assist 

RWQCBs and stakeholders in identifying whether there is a current or potential water quality 

issue requiring attention [Compliance Status], the nature of the identified water quality issue 

[Screening-level Evaluation], and possible action to address the issue [Potential Options]. 

Based on this information, the RWQCB and stakeholders can determine whether a special study 

is needed and the scope of the study. This approach can help avoid initiation of costly and timeconsuming studies which are not appropriately designed to resolve the specific issue in question. 

 The decision tree is not meant to preclude the exploration of any other creative solutions; it is 

meant to encourage constructive dialogue among stakeholders. 

Two specific considerations should be kept in mind when conducting the pre-evaluation 

suggested by this decision tree. First, users must be familiar with the quality of the data under 

review and the potential need to augment data which are not of adequate quality. Second, users 

should know what the existing beneficial uses are (i.e., uses attained since 1975). 

Special Studies Process

A. Workplan 

If appropriate, the RWQCB may participate in developing a detailed workplan with interested 

persons (which can include, but are not limited to, U.S. EPA, the RWQCB, the SWRCB, and 

affected dischargers) prior to proceeding with a special study. The workplan may include the 

following elements: 

(1) Formation of a project team for the workplan, which may include the Department of Fish 

and Game, the U.S. Fish and Wildlife Service, and other stakeholders; 

(2) Purpose of the workplan; 

(3) Responsibilities of the persons associated with the workplan; 

(4) Budget and cost-sharing plan. This plan must be determined on a case-by-case basis; 

however, the SWRCB encourages sharing of costs (based on availability of funding), 

where there are multiple persons who wish to support the goals of the study; 

(5) Development of the following elements: 

 (a) Identification of tasks(s), 

(b) Purpose of tasks(s), 

(c) Method by which task(s) will be implemented, 

(d) Products of the tasks(s), 

(e) Schedule for the task(s), 

(f) Responsibility for implementing the task(s), and 

(g) Budget and funding for the task(s); 

APPENDIX 5 - 4 
(6) Administrative policies and procedures to govern oversight of the special studies process 

(e.g., amending the workplan, conflict resolution, etc.); and 

 (7) Project schedule. 

B. Scientific Review Panel 

If, during the data interpretation phase of a special study, the RWQCB, SWRCB, U.S. EPA, or 

other stakeholders have differing opinions with regard to the interpretation of data, the RWQCB 

and stakeholders may want to seek the advice of an independent scientific review panel. The 

method of selecting the panel, cost reimbursement, and other details regarding the conflict 

resolution process could be included in the workplan. 

C. Compliance Schedule 

A permit compliance schedule (as described in section 2.1) may allow sufficient time for 

collection of data, completion of a study, and determination of compliance measures. While 

special studies are being conducted, interim requirements may be established by the RWQCB (as 

described in section 2.2). However, in no event may a compliance schedule exceed the time 

period allowed in this Policy, unless an exception has been granted. 

D. Environmental and Economic Impacts 

To ensure that environmental and economic impacts are adequately addressed, the RWQCB staff 

shall, as part of the special study workplan: 

(1) Comply with CEQA, if applicable; and 

(2) Direct the preparation of an analysis documenting economic impacts if site-specific 

objectives or a change in designated beneficial uses is being considered under 

40 CFR 131.10(g)(6), revised as of July 1, 1997. 

E. Antidegradation and Other Legal Requirements 

RWQCB staff shall, as part of the special study workplan, ensure compliance with SWRCB 

Resolution No. 68-16 (Statement of Policy with Respect to Maintaining High Quality of Waters 

in California) and any other applicable legal requirements. 

APPENDIX 5 - 5 
Yes 4. Are criteria / 

objectives exceeded?

5. Is there any other 

evidence of relevant water 

quality impacts

Yes 

1a. Does/will the

discharge(s) exceed

existing or potential

permit limits?

1b. If no permit, 

does/will the 

discharge(s) cause

exceedances of 

criteria/objectives?

No 

1c. If no permit and no specific 

discharge under review, are/will the 

criteria/objectives be exceeded

Yes 

2a. Are there water 

pollution control 

measures which 

might improve the 

discharge quality?

Yes 

2b. Are there BMPs

which might improve 

the discharge quality?

Go to#3 

4. Are criteria /objectives

 exceeded?

No 

5. Is there any other evidence of 

relevant water quality impacts?

No 

6. Are there permit relief options which will result in permit 

compliance while maintaining receiving water quality?

8. Are beneficial uses and 

relevant criteria/objectives all 

appropriate for the waterbody?

10. Are beneficial uses appropriate, 

but not criteria/objectives?

No 

No 

12. Are beneficial uses 

inappropriate?

No 

Go to#3 

Yes 

3. Consider implementation of 

 water pollution control measures 

and/or BMPs. Continue to #4 of 

appropriate

Yes 9. Conduct a Total Maximum

Daily Load (TMDL) analysis &

Implement the results.

Yes 

11. Conduct a Site Specific 

Objectives (SSO) analysis & 

Implementation.

Yes 

13. Conduct a Use Attainability 

Analysis (USAA) & implement results 

If necessary or adopt new use.

Yes 

Yes 

Yes 

No 

Yes 

No 

7. Implement permit relief options. 

Continue to #8 if full compliance will 

Not be achieved by this means

Go to 

START to 

determine 

compliance 

status

Go to#8 

IN COMPLIANCE 

Go to#8 

Potential Options

Pre-Evaluation for Special Studies

Decision Tree with Attached Narrative Discussion 

Screening-level Evaluation

No 

No 

Compliance Status

No 

No 

APPENDIX 5 - 6 

START 

with 1a., 1b., 

or 1c.
Narrative Discussion of Decision Tree:

la. Does/will a discharge exceed existing or potential permit limits for toxic pollutants? This 

question applies to discharges regulated by a National Pollutant Discharge Elimination 

System (NPDES) permit or Waste Discharge Requirements (WDRs). If the discharge(s) in 

question is not regulated by a discharge permit, proceed to #1b. It is assumed that data 

used to answer this question are reliable. 

1b. If no permit, does the discharge(s) cause exceedances of criteria/objectives? This question 

primarily applies to nonpoint discharges, though it could conceivably apply to point source 

discharges which are not currently permitted. It is assumed that data used to answer this 

question are reliable. 

1c. If no permit and no specific discharge(s) are under review, are criteria/objectives 

exceeded? It is assumed that data used to answer this question are reliable. 

2a. Are there water pollution control measures which might improve the water quality? A 

water pollution control program may include, as appropriate: pollution control 

technologies; pretreatment requirements; and pollution prevention, waste minimization, 

and source control measures. This question is meant to elicit consideration of effluent 

quality control measures which could be implemented as a full or partial solution to the 

identified permit noncompliance issue. It is not intended as a barrier to the exploration of 

other potential forms of regulatory adjustment. 

2b. Are there Best Management Practices (BMPs) which might improve water quality? BMPs 

are pollution management measures designed to reduce the water quality impacts, where 

they exist, associated primarily with non-point source discharges. As with #2a above, this 

question is meant to elicit consideration of discharge control measures which could be 

implemented as a full or partial solution to the identified noncompliance issue. It is not 

intended as a barrier to the exploration of other potential forms of regulatory adjustment. 

3. Consider whether implementation of water pollution control measures and/or BMPs will 

lead to compliance. Simultaneously, continue to #4 if deemed appropriate, considering 

such questions as whether or not full compliance will be achieved by these means, or 

whether it would be cost effective. As stated, the simple determination that 

implementation of pollution control measures and/or BMPs might improve the discharge or 

water quality should not preclude the exploration of other potential regulatory adjustment 

options, as well. For clarity, the reviewer should proceed not to box four prime, but to box 

four. 

4. Are criteria/objectives exceeded? It is assumed that data used to answer this question are 

reliable and appropriate hardness adjustments have been made. 

APPENDIX 5 - 7 
5. Is there any other evidence of relevant water quality impacts? This question is meant to 

capture those situations, where the criteria/objective for the pollutant of concern do not 

exist or appear to be under protective. "Other evidence" might include: bioconcentration or 

biocriteria data, population studies, food web analyses, etc. Impacts to wildlife should be 

considered as should impacts to threatened and endangered species. The potential for 

impacts to be of a seasonal nature should also be considered in this pre-evaluation. 

"Relevant water quality impacts" are those impacts which have a demonstrable relationship 

to the pollutant(s) of concern. 

6. Are there permit relief options which will result in permit compliance while maintaining 

receiving water quality? Permit relief options might include, where appropriate: 

development of a mixing zone, modification of the averaging periods, adoption of a 

variance, etc. For unpermitted discharges or pre-evaluations involving no specific 

discharges, the user should continue to box #8. 

7. Implement permit relief options. Continue to #8 if full compliance will not be achieved by 

these means. The development of permit relief options would occur through a request to 

the RWQCB. 

8. Are beneficial uses and criteria/objectives both appropriate for the water body? To answer 

this question, a screening-level evaluation may be necessary, including an evaluation of the 

associated regulatory history; the site-specific conditions; and the status of current, 

applicable scientific understanding. It is assumed that data used to answer this question are 

reliable. 

This question is best answered when a watershed stakeholder group has formed and 

collectively either: 1) evaluated the condition of the watershed through a watershed 

management plan, 2) evaluated the condition of the watershed through less formal means, 

or 3) convened discussions regarding the condition of the watershed. If one does not 

currently exist, a watershed stakeholder group should be formed if it appears to be a useful 

forum for discussion and review. The following more specific questions may apply: 

• Is the water effluent dominated, agricultural drainage water dominated, etc.? These 

water bodies may be likely candidates for the appropriate application of regulatory 

adjustments (e.g., SSO or UAA). 

• Were the current beneficial uses applied on a national, state-wide, or region-wide basis or 

have they been specifically designated for the water body in question? While not the 

only candidates, water bodies for which beneficial uses have been applied on a national, 

state-wide, or region-wide basis may be candidates for the appropriate application of 

regulatory adjustments (e.g., SSO). 

• Are there rare, threatened, or endangered species, or ecological conditions which the 

currently applied beneficial uses do not adequately describe or the water quality 

objectives do not fully protect?

APPENDIX 5 - 8 
• Has the beneficial use and the water quality necessary to maintain the beneficial use been 

attained since 1975?

• How do anti-degradation requirements apply?

• Are elevated constituents the result of 1) natural phenomena or 2) anthropogenic 

activities that ceased prior to 1975?

• Do the currently designated beneficial uses protect all existing and appropriate potential 

uses?

• Are natural, ephemeral, intermittent, or low flow conditions or water levels preventing 

the attainment of the designated non-existing uses?

• Are there human-caused conditions or sources of pollution which prevent attainment of 

the uses but either cannot be remedied or would cause greater environmental damage if 

corrected? 

• Does the presence of dams, diversions, or other types of hydrologic modifications 

preclude the attainment of designated non-existing beneficial uses?

• Do the physical conditions of the water body preclude attainment of aquatic life 

protection uses (i.e., lack of proper substrate, cover, flow, depth, pools, riffles, and the 

like)? 

• Does attainment of designated beneficial uses require the application of controls which 

would result in substantial and widespread economic and social impact?

• Have the appropriate water characteristics (e.g., hardness, pH) been accounted for in the 

CTR criteria?

• Has an appropriate set of species been evaluated in setting the CTR criteria and toxicity 

objective? 

9. Conduct a total maximum daily load analysis and implement the results. Conducting a 

TMDL could result in, among other things, waste load allocations, BMP implementation 

for non-point dischargers, and/or effluent trading options for point and non-point source 

dischargers. (See Appendix 6 regarding TMDLs.) 

10. Are beneficial uses appropriate but not criteria/objectives for toxic pollutants? See #8 

above. 

11. Conduct a site-specific objectives analysis. An SSO study will include one or more of the 

following activities: 

APPENDIX 5 - 9 
• Recalculation of objective; 

• Water effects ratio or other similar method; or 

• Any scientifically defensible process.

U.S. EPA's "Guidelines for Deriving Numerical Aquatic Site Specific Water Quality 

Criteria by Modifying National Criteria," dated 1984 (EPA-600/3-84-099) provides 

guidance for conducting an SSO study. 

U.S. EPA's "Water Quality Standards Handbook" dated 1994 also provides general 

guidance in this area. 

12. Are beneficial uses inappropriate? See #8 above. 

13. Conduct a use attainability analysis (UAA) and implement the results. When a use is 

proposed for dedesignation, i.e., removed or replaced with a subcategory requiring less 

stringent standards, a UAA is necessary. In a case where a use is proposed to be added, a 

UAA is not necessary. A new use designation can be added for a water body following the 

normal public review process. A UAA will determine if physical, chemical, and/or 

biological factors affect the attainability of a designated use via a water body survey and 

assessment. An analysis of economic factors can also be included to determine whether 

substantial and widespread economic and social impacts would be caused by stringent 

pollution control requirements. 

U.S. EPA's "Technical Support Manual: Water body Survey and Assessment for 

Conducting Use Attainability Analyses" dated 1983 provides guidance for conducting a 

UAA as does Region 9's Interim Final "Guidance for Modifying Water Quality Standards 

and Protecting Effluent-Dependent Ecosystems" dated 1992. U.S. EPA's "Water Quality 

Standards Handbook" dated 1994 also provides general guidance in this area. 

APPENDIX 5 - 10 
APPENDIX 6 

Watershed Management and TMDLs

Watershed Management

The SWRCB will utilize and promote, to the extent feasible, a watershed approach to address 

water quality issues involving toxic pollutants. Compared to the more traditional, programmatic 

approach to water management, the watershed approach can look at all types of pollution and all 

sources of pollution. One consequence of the more global perspective is that attention can be 

trained on the most effective strategies for management (rather than the most programmatically 

expedient). Another consequence is that a much larger universe of interested persons becomes 

important to the management of water quality, and the ability to work with these people creates 

added value for water management. In utilizing the watershed approach, the SWRCB will work 

to marshall the expertise and resources of other agencies and the private sector to collaboratively 

manage water quality. 

In a collaborative, stewardship effort, local interests are engaged with State and federal interests, 

and land managers, to work with water managers to solve complex resource management 

problems. A watershed perspective can also enhance interagency coordination by focusing 

programs on resource needs throughout the watershed. 

Watershed management is an integrated holistic approach for restoring and protecting aquatic 

ecosystems and protecting human health in a geographic area. Watershed management may 

include diverse issues as defined by the watershed's stakeholders (persons with some interest in 

the watershed) to ensure comprehensive solutions. It reflects a growing consensus that many of 

the existing water quality problems can be best addressed by a more integrated, basin-wide 

approach. The purpose of watershed management is variously viewed as (1) a method for 

increasing participation at the local level in water quality protection, (2) an approach to reducing 

the impact of nonpoint sources, (3) a strategy for integrating management of all components of 

aquatic ecosystems, and (4) a process for optimizing the cost effectiveness of a blend of point 

and nonpoint source control efforts. 

Whichever purpose or blend of purposes predominates, watershed management is not a new 

centralized program that competes with or replaces existing programs. The significant 

advantage of the watershed management approach is that it encourages a collaborative, 

stewardship-driven process where diverse interests (individuals, landowners, farmers, POTWs, 

industries, environmentalists, and agencies) can work in conjunction with SWRCB and RWQCB 

staff to develop a consensus on, and share responsibility for, addressing water quality problems. 

The watershed approach assumes all stakeholders are brought to the table; therefore, there should 

be one watershed group that can develop a plan for the watershed that addresses the interests of 

stakeholders in the watershed. Furthermore, watershed management provides a mechanism for 

considering social and economic interests, in the context of resolving water quality issues. The 

SWRCB and RWQCBs will work to preserve the integrity of the watershed process and facilitate 

an open and timely resolution of issues. 

APPENDIX 6 - 1 
In some cases, there is no active watershed management group that has evolved far enough to 

have identified key issues, boundaries, objectives, and early actions. In these instances, a group 

of government agencies may work together to define the conditions in a water body and to 

identify the specific parameters contributing to beneficial use impairments. In any event, the 

RWQCBs may have to act more or less independently to meet legal requirements using primarily 

in-house staff. Participation from other interested persons, under these circumstances, is 

accomplished through the SWRCB and RWQCB public hearing processes. 

Watershed management planning and implementation actions will occur primarily at the 

RWQCB and local level. However, the SWRCB will provide training in stewardship and 

watershed management, and support educational efforts involving K through 12 programs as 

well as land owners/managers. 

TMDLs and Watershed Management

TMDLs are required for all waters listed pursuant to CWA Section 303(d)(1)(A). The SWRCB 

is committed to expeditiously addressing these water quality problems. 

A TMDL establishes the amount of a pollutant that may be discharged into a water body and still 

maintain water quality standards with seasonal variations and a margin of safety that takes into 

account any lack of knowledge concerning the relationship between effluent limitations and 

water quality. The TMDL process is defined in federal regulations (40 CFR 130.7, revised as of 

July 1, 1996) and generally consists of five steps: 

(1) Identification by each state of water quality-limited waters that do not now, or are not 

expected to, attain state water quality standards after implementation of technology-based 

effluent limitations, more stringent effluent limitations required by federal, State, or local 

authority, and other pollution control requirements (e.g., best management practices) 

required by local, State, or federal authority, and identification of impairment; 

(2) Establishment of priority rankings for the development of TMDLs; 

(3) Development of waste load allocations (WLAs), load allocations (LAs), and TMDLs; 

(4) Incorporation of the loadings in the RWQCB basin plans; and 

(5) Submittal of segments identified, priority ranking, and loads established to U.S. EPA for 

approval. 

Development of TMDLs can utilize the watershed approach to assess and identify water qualitylimited segments and pollutants causing impairment, identify sources, and allocate pollutant 

loads. The watershed approach may address a broader range of issues than the TMDLs, but the 

approach can: (1) result in achieving or maintaining water quality standards so that waters are 

not added to the 303(d) list; (2) result in attainment of water quality standards, through means 

other than the TMDL process, so that waters can be removed from the 303(d) list; or (3) be used 

to develop TMDLs. A watershed group can develop a TMDL if the TMDL complies with 

applicable federal requirements. 

APPENDIX 6 - 2 
SISKIYOU

MODOC

DEL

NORTE

HUMBOLDT

TRINITY SHASTA LASSEN

PLUMAS

TEHAMA

SIERRA

NEVADA

PLACER

EL DORADO

AMADOR

CALAVERAS

ALPINE

BUTTE GLENN MENDOCINO

LAKE

NAPA

COLUSA YUBA

SUTTER

SACRAMENTO

YOLO SONOMA

ALAMEDA

MARIN

SAN

JOAQUIN

TUOLUMNE

MARIPOSA

MONO

STANISLAUS

SAN MATEO

SAN

FRANCISCO

SANTA

CLARA

SANTA CRUZ

MERCED

FRESNO INYO

TULARE

KINGS

MONTEREY

SAN LUIS

OBISPO

SANTA

BARBARA

KERN

VENTURA

LOS

ANGELES

SAN

BERNARDINO

ORANGE

SAN

BENITO

RIVERSIDE

IMPERIAL

SAN DIEGO

MADERA

SOLANO

CONTRA

COSTA

State of California

Arnold Schwarzenegger, Governor

California Environmental Protection Agency

Dr. Alan Lloyd, Secretary

State Water Resources Control Board

Arthur G. Baggett, Jr., Chair

Celeste Cantú, Executive Director

Office of Public Affairs: (916) 341-5254

Office of Legislative Affairs: (916) 341-5251

Financial Assistance information: (916) 341-5700

Water Quality information: (916) 341-5455

Water Rights information: (916) 341-5300

CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARDS

1/12/05

P.O. Box 100, Sacramento, CA 95812-0100 • www.waterboards.ca.gov

info@waterboards.ca.gov

NORTH COAST REGION (1)

www.waterboards.ca.gov/northcoast

5550 Skylane Blvd., Suite A

Santa Rosa, CA 95403

info1@waterboards.ca.gov

(707) 576-2220 TEL • (707) 523-0135 FAX

SAN FRANCISCO BAY REGION (2)

www.waterboards.ca.gov/sanfranciscobay

1515 Clay Street, Suite 1400

Oakland, CA 94612

info2@waterboards.ca.gov

(510) 622-2300 TEL • (510) 622-2460 FAX

CENTRAL COAST REGION (3)

www.waterboards.ca.gov/centralcoast

895 Aerovista Place, Suite 101

San Luis Obispo, CA 93401

info3@waterboards.ca.gov

(805) 549-3147 TEL • (805) 543-0397 FAX

LOS ANGELES REGION (4)

www.waterboards.ca.gov/losangeles

320 W. 4th Street, Suite 200

Los Angeles, CA 90013

info4@waterboards.ca.gov

(213) 576-6600 TEL • (213) 576-6640 FAX

CENTRAL VALLEY REGION (5)

www.waterboards.ca.gov/centralvalley

11020 Sun Center Drive, Suite 200

Rancho Cordova, CA 95670

info5@waterboards.ca.gov

(916) 464-3291 TEL • (916) 464-4645 FAX

Fresno branch office

1685 E Street, Suite 200

Fresno, CA 93706

(559) 445-5116 TEL • (559) 445-5910 FAX

Redding branch office

415 Knollcrest Drive

Redding, CA 96002

(530) 224-4845 TEL • (530) 224-4857 FAX

LAHONTAN REGION (6)

www.waterboards.ca.gov/lahontan

2501 Lake Tahoe Blvd.

South Lake Tahoe, CA 96150

info6@waterboards.ca.gov

(530) 542-5400 TEL • (530) 544-2271 FAX

Victorville branch office

15428 Civic Drive, Suite 100

Victorville, CA 92392

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COLORADO RIVER BASIN REGION (7)

www.waterboards.ca.gov/coloradoriver

73-720 Fred Waring Dr., Suite 100

Palm Desert, CA 92260

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SANTA ANA REGION (8)

www.waterboards.ca.gov/santaana

California Tower

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Riverside, CA 92501-3339

info8@waterboards.ca.gov

(951) 782-4130 TEL • (951) 781-6288 FAX

SAN DIEGO REGION (9)

www.waterboards.ca.gov/sandiego

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San Diego, CA 92123

info9@waterboards.ca.gov

(858) 467-2952 TEL • (858) 571-6972 FAX

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