Total Maximum Daily Loads 

For Toxic Pollutants 

San Diego Creek and Newport Bay, California 

U.S. Environmental Protection Agency 

Region 9 

Public Review Draft 

April 12, 2002 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Table of Contents 

Summary TMDL Document 

I. Introduction....................................................................................... 2 

II. Overview of TMDLs and Available Data....................................................11 

III. Organophosphate (OP) Pesticide TMDLs....................................................22 

IV. Selenium TMDLs................................................................................30 

V. Metals TMDLs...................................................................................39 

VI. Organochlorine Compound TMDLs..........................................................50 

VII. Chromium and Mercury TMDLs..............................................................61 

VIII. Arsenic Analysis.................................................................................67 

IX. References........................................................................................69 

X. Glossary/Abbreviations.........................................................................74 

Technical Support Documents 

A. Relevant Maps 

B. Freshwater Flow and Seasonal Variations 

C. Organophosphate Pesticides 

D. Selenium 

E. Metals 

F. Organochlorine Compounds 

G. Chromium and Mercury 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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I. Introduction 

What Is the Purpose of This Action? 

 This document describes Total Maximum Daily Loads (TMDLs) being established for several 

toxic pollutants by U.S. Environmental Protection Agency (EPA) to help protect and restore the water 

quality of Newport Bay, San Diego Creek, and their tributaries. A TMDL identifies the maximum 

amount of a pollutant that may be discharged to a water body without causing exceedences of water 

quality standards and impairment of the uses made of these waters. The federal Clean Water Act 

requires development of TMDLs for polluted waters to assist in identifying pollutant control needs and 

opportunities. EPA is establishing these TMDLs pursuant to a 1997 consent decree in which EPA 

committed to ensure that these TMDLs would be established in 2002. EPA has worked closely with the 

California Regional Water Quality Control Board, Santa Ana Region (Regional Board) in the development 

of these TMDLs. Although the State has primary responsibility for developing TMDLs under the Clean 

Water Act, the State was unable to complete its formal adoption of these TMDLs by the consent decree 

deadline; hence EPA is required to establish the TMDLs at this time. 

What Is A TMDL?

 Section 303(d)(1)(A) of the Clean Water Act (CWA) requires that "Each State shall identify those 

waters within its boundaries for which the effluent limitations...are not stringent enough to implement 

any water quality standard applicable to such waters.” The CWA also requires states to establish a 

priority ranking for waters on the 303(d) list of impaired waters and establish Total Maximum Daily 

Loads (TMDLs) for such waters. As part of California’s 1996 and 1998 Section 303(d) lists, the Regional 

Board identified Newport Bay and San Diego Creek as water quality limited due to several toxic 

pollutants (in addition to other pollutants not addressed in these TMDLs) and designated this watershed 

as a high priority for TMDL development. 

 The elements of a TMDL are described in 40 CFR 130.2 and 130.7 and Section 303(d) of 

the CWA, as well as in EPA guidance documents (e.g., EPA, 1991 and EPA, 2001). A TMDL is 

defined as “the sum of the individual waste load allocations for point sources and load 

allocations for nonpoint sources and natural background” (40 CFR 130.2) such that the capacity 

of the water body to assimilate pollutant loadings (the Loading Capacity) is not exceeded. A 

TMDL is also required to be developed with seasonal variations and include a margin of safety 

to address uncertainty in the analysis. In addition, pursuant to the regulations at 40 CFR 130.6, 

states must develop water quality management plans which incorporate approved TMDLs and 

implementation measures necessary to implement the TMDLs. 

 Upon establishment of TMDLs by EPA or the State, the State is required to incorporate 

the TMDLs along with appropriate implementation measures into the State Water Quality 

Management Plan (40 CFR 130.6(c)(1), 130.7). The Regional Board Basin Plan, and applicable 

state-wide plans, serve as the State Water Quality Management Plan governing the Newport Bay 

watershed. If the State subsequently adopts and submits for EPA approval TMDLs which are 

different from the TMDLs established by EPA, EPA will review the State-submitted TMDLs to 

determine if they meet all TMDL requirements. If EPA approves the State TMDLs, they will 

supercede the TMDLs being established now by EPA. 
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Why Is EPA Establishing These TMDLs? 

 

 The Environmental Protection Agency (EPA) has oversight authority for the 303(d) 

program and is required to review and either approve or disapprove the TMDLs submitted by 

states. If the EPA disapproves a TMDL submitted by a state, the EPA is required to establish a 

TMDL for that water body. 

 On October 31, 1997, EPA entered into a consent decree (decree), Defend the Bay, Inc. 

v. Marcus, (N.D. Cal. No. C 97-3997 MMC), which established a schedule for development of 

TMDLs in San Diego Creek and Newport Bay. The decree required development of TMDLs 

for several toxic pollutants by January 15, 2002. The agreement also provided that EPA would 

establish the required TMDLs within ninety (90) days, if the State failed to establish an approved 

TMDL by the deadline. In early 2002, the decree was modified to extend the deadline for EPA 

establishment of these TMDLs to June 15, 2002. 

Pursuant to the decree, EPA Region 9 and the Regional Board have already established 

sediment and nutrient TMDLs for San Diego Creek and Newport Bay. EPA has also approved 

state-adopted TMDLs for fecal coliform in Newport Bay. 

 The RWQCB has conducted extensive analysis in support of these toxic pollutant 

TMDLs and has proposed to adopt TMDLs and associated implementation plans for two 

pesticides and selenium. However, the State of California has not yet adopted TMDLs for any of 

the toxic pollutants covered by the decree. Therefore, in compliance with the terms of the 

decree, EPA is now proposing to establish the TMDLs for these toxic pollutants in order to meet 

the requirements of the decree. EPA is proposing the TMDLs described in this document and 

providing the public with the opportunity to comment on the draft TMDLs. EPA will consider 

any comments received during the comment period (up until May 28) in our final TMDL 

decisions, which will be made by June 15, 2002. 

What TMDLs Are Being Established? 

EPA is establishing TMDLs for several toxic pollutants which are exceeding applicable 

State water quality standards: selenium; several heavy metals; and several organic chemicals 

including modern pesticides (i.e., diazinon and chlorpyrifos) and legacy pesticides (DDT, 

Chlordane etc.) and polychlorinated biphenyls (PCBs). The pesticide diazinon is being 

addressed by these TMDLs because the State found that it is associated with significant water 

toxicity in San Diego Creek and concluded that it should be addressed concurrent with the 

similar pesticide chlorpyrifos, which is addressed by the consent decree. These TMDLs are 

being developed for specific water bodies in the Newport Bay watershed for which available data 

indicate that water quality is impaired. Table 1-1 lists the specific water bodies and associated 

pollutants for which TMDLs are being established. 
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Table 1-1 Toxic pollutants per waterbody requiring TMDL development. 

California’s Section 303(d) list of impaired waters does not specifically name each of 

these water body-pollutant combinations. The 1996 Section 303(d) list identified Newport Bay 

and San Diego Creek as impaired due to metals, pesticides and priority organics. The 1998 

Section 303 (d) list added “unknown toxicity” to one specific part of San Diego Creek—Reach 2. 

During the negotiation of the consent decree, Regional Board staff provided a more specific list 

of pollutants covered by these general pollutant categories used in the listing decisions, and the 

consent decree refers to this more specific pollutant list. In 2001-02, EPA and Regional Board 

staff carefully evaluated more recent water quality data to help determine whether TMDLs were 

needed for each of the toxic pollutants identified in the decree. As described in EPA Region 9’s 

assessment of water quality in San Diego Creek and Newport Bay (2001), and in this summary 

TMDL document below, EPA and the State determined that the list of water body-pollutant 

combinations warranting TMDL development should be fine-tuned to reflect the best current 

information concerning water body impairment. Based on our assessment of the most current 

local data and national EPA guidance concerning arsenic, EPA has concluded that TMDLs are 

not needed for arsenic for waters in the Newport Bay watershed. 

Why Are These Pollutants Of Concern to EPA and the State? 

By definition, toxic substances are poisonous through chemical action that may result in 

adverse impacts to humans or other living organisms. Adverse impacts may include, but are not 

limited to, cellular injury, mutagenic impairment, reduced reproductive success, and 

carcinogenic responses. Two primary adverse impacts are associated with toxic substances in 

these water bodies: a) chemicals may bioaccumulate and are harmful to human health when we 

consume fish or shellfish and b) chemical concentrations in water, sediment or biota may cause 

ecological risks. Available data indicate that the pollutants addressed in these TMDLs were 

found in water column, bottom sediments, or fish tissue at potentially unsafe levels which exceed 

applicable water quality standards. There is no current evidence of adverse effects on human 

health due to consumption of contaminated fish or direct exposure to toxic pollutants. Evidence 

of adverse impacts to aquatic life as a result of direct or indirect exposures to these toxic 

pollutants is limited. However, because the pollutants addressed in these TMDLs have the 

potential to cause short term adverse impacts to aquatic life or long term human health and 

aquatic life impacts due to pollutant bioaccumulation, actions to reduce discharges of these 

pollutants to the aquatic environment are warranted. The TMDLs are designed to assist in 

targeting pollutant reduction activities. 

WaterBody (Type) Element/ Metal Organic compound 

San Diego Creek 

(freshwater) 

Cd, Cu, Pb, Se, Zn Chlorpyrifos, Diazinon, 

Chlordane, Dieldrin, DDT, 

PCBs,Toxaphene 

Upper Newport Bay 

(saltwater) 

Cd, Cu, Pb, Se, Zn Chlorpyrifos, Chlordane, DDT, 

PCBs 

Lower Newport Bay 

(saltwater) 

Cu, Pb, Se, Zn Chlordane, Dieldrin, DDT, PCBs 

Rhine Channel, within Lower 

Newport Bay (saltwater) 

Cu, Pb, Se, Zn, Cr, 

Hg 

Chlordane, Dieldrin, DDT, PCBs 
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How Are the TMDL Documents Organized? 

This document provides summary information about the Toxic Pollutant TMDLs, 

including a description of the environmental problems, water body goals, source analysis, 

loading capacity (i.e., TMDL), and loading allocations for each toxic pollutant TMDL. The 

document also describes how other federally-required TMDL components (i.e., margin of safety 

to account of analytical uncertainty, and critical conditions and seasonal variations associated 

with water body flow and pollutant loadings) are addressed. Individual pollutants have been 

grouped together based on chemical characteristics as follows: 

Organophosphate (OP) Pesticides—diazinon and chlorpyrifos are two organophosphate 

pesticides with similar sources and impairment primarily limited to San Diego Creek. 

Selenium—is a toxic bioaccumulative metal,with significant groundwater sources 

Metals—cadmium, copper, lead and zinc have similar aqueous behavior and affect nearly all 

water bodies 

Organochlorinated compounds—PCBs, DDT, chlordane, dieldrin and toxaphene have similar 

fate (bioaccumulation) and transport mechanisms (primarily from watershed soils to freshwater 

and saltwater sediments) for all waterbodies. 

Mercury and Chromium—are two metals with very small geographical areas of impairment. 

 The State and EPA initially found that arsenic was present at levels of concern in Upper 

and Lower Newport Bay; however, based on more recent data and new information concerning 

arsenic conditions in saltwater bodies, EPA has now concluded that Newport Bay and its 

tributaries are not impaired due to arsenic pollution. This summary document includes a section 

describing the basis for this conclusion in greater detail. The consent decree governing 

development of these TMDLs contains provisions that authorize EPA to make a determination 

that TMDLs are not needed for individual waters and/or pollutants if available data and 

information support those determinations. Pursuant to these decree provisions, EPA is making 

the determination that arsenic TMDLs are not needed for waters in the Newport Bay watershed. 

EPA has prepared several Technical Support Documents (TSDs) to accompany this 

summary TMDL document. The TSDs provide considerably more detailed information relevant 

to each pollutant (grouped together as described above). The TSDs describe chemical 

characteristics of each toxicant, the basis for numeric targets, a complete source analysis, an 

explanation of how we calculated the loading capacity, and related information. A TSD is also 

provided that discusses EPA’s analysis of freshwater flows in San Diego Creek, which was used 

to identify the appropriate numeric targets for certain pollutants, address seasonal variations and 

critical conditions in flows and pollutant loads, and evaluate the best approaches for calculating 

pollutant loading capacities and allocations. Another TSD provides more maps of the San Diego 

Creek, Santa Ana-Delhi Channel and Newport Bay watersheds and analysis concerning water 

residence times in Upper and Lower Bay. Once the TMDLs become final, a summary of public 

comments and EPA’s responses to those comments will be provided in another TSD. 
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What Happens After The TMDLs Are Established? 

 TMDLs are not self-implementing—they must be implemented by the State and the 

entities that are discharging pollutants of concern. Federal regulations require states to adopt 

TMDLs and associated implementation measures in the State Water Quality Management Plan 

(i.e., the Basin Plan) (40 CFR 130.6). The State of California’s procedure for adopting TMDLs 

and associated implementation measures is through amendments to the Basin Plans. These 

amendments are developed by the Regional Board staff, then approved by the Regional Board, 

State Water Resources Control Board, and State Office of Administrative Law. The 

amendments are then submitted to EPA for approval. (If the TMDLs adopted by the State are 

different from the TMDLs established by EPA then the TMDLs must be resubmitted to EPA for 

approval.) 

Three general categories of pollutant sources are identified in these TMDLs: 

• Nonpoint sources, which discharge pollutants through diffuse runoff from the 

land, primarily in response to rainfall runoff, and which are addressed by the State 

through a combination of voluntary and regulatory measures outlined in 

California’s State Nonpoint Source Management Plan. 

• Point sources, which discharge pollutants through discrete pipes or conveyances 

and which are addressed through regulatory provisions of the National Pollutant 

Discharge Elimination System (NPDES) permit program. Several sources of 

pollutant runoff from roads and urban areas in the Newport Bay watershed are 

addressed through NPDES stormwater permits. There are a small number of 

additional permitted point source discharges in the watershed which are addressed 

in the TMDLs, including several groundwater dewatering operations. 

• Pollutants already in water body sediments, which are usually associated with 

contaminated sediments discharged to water bodies in the past, but which retain 

and release significant quantities of pollutants to the ecosystem. These 

contaminated sediments may be concentrated to the point where remediation or 

removal action is warranted to remove the contaminated material, or they may be 

so diffuse that remedial action would be ineffective. 

The federal Clean Water Act creates federal regulatory jurisdiction only over point 

sources; therefore, the direct effect of EPA’s TMDLs is that NPDES permits for point source 

discharges addressed in the TMDLs will need to be modified as necessary to be consistent with 

the TMDLs. Permit modification may occur when the permits are reopened or reissued. Federal 

regulations require that NPDES permits must be consistent with wasteload allocations specified 

in TMDLs, and the State has some discretion in determining the appropriate permit provisions to 

ensure consistency. 

Although the TMDLs include allocations which address nonpoint source and 

contaminated sediments, implementation of these allocations is usually based on the TMDL 

implementation plan developed by the State as part of its Basin Plan amendment process 

described above. The State of California has broad authority under State law to apply voluntary 

or regulatory approaches to addressing these source categories. Past TMDL implementation 

plans in California have provided for State-issued “Waste Discharge Requirements” for some 
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nonpoint sources, remedial action plans to address contaminated sediment sites, and 

opportunities for voluntary action to comply with load allocations. The Regional Board is 

currently in the process of developing implementation plans for several of the toxic pollutant 

TMDLs and will address the remaining toxic pollutant TMDLs in the near future. 

The U.S. Army Corps of Engineers and Orange County have been examining the 

feasibility of removing sediment from containment basins in Upper Newport Bay (ACOE 2000). 

This study has refined various alternatives, obtained necessary funding and is presently entering 

the preconstruction, engineering and design phase. Remediation is scheduled to begin in 

2003/2004. The provisions of these toxic pollutant TMDLs could affect the sediment removal 

project, and EPA and the Regional Board intend to coordinate with the project sponsors to 

discuss this potential issue. 

EPA’s pesticide program has intiated a phase-out of household uses of diazinon and 

chlorpyrifos (EPA 2000b, EPA 2001b). It is expected that the phase-out will greatly assist in 

reducing the levels of these pesticides found in the waters of Newport Bay watershed. 

Environmental Setting 

The Newport Bay/San Diego Creek watershed is located in Central Orange County in the 

southwest corner of the Santa Ana River Basin, about 35 miles southeast of Los Angeles and 70 

miles north of San Diego (see Figure 1-1 in TSD—Part A). The watershed encompasses 154 

square miles and includes portions of the Cities of Newport Beach, Irvine, Laguna Hills, Lake 

Forest, Tustin, Orange, Santa Ana, and Costa Mesa. Mountains on three sides encircle the 

watershed; runoff from these mountains drains across the Tustin Plain and enters Upper Newport 

Bay via San Diego Creek. Newport Bay is a combination of two distinct water bodies - Lower 

and Upper Newport Bay, divided by the Pacific Coast Highway (PCH) Bridge. The Lower Bay, 

where the majority of commerce and recreational boating exists, is highly developed. The Upper 

Bay contains both a diverse mix of development in its lower reach and an undeveloped 

ecological reserve to the north. 

San Diego Creek flows into Upper Newport Bay and is divided into two reaches. Reach 

1 is located downstream of Jeffrey Road and Reach 2 lies upstream of Jeffrey Road to the 

headwaters. The San Diego Creek watershed (ca. 105 square miles) is divided into two main 

tributaries: 

• Peters Canyon Wash, which drains Peters Canyon, Rattlesnake Canyon, and Hicks 

Canyon Washes that have their headwaters in the foothills of the Santa Ana Mountains, 

and 

• San Diego Creek itself, which receives flows from Peters Canyon Wash in Reach 1 and 

includes Bee Canyon, Round Canyon, Agua Chinon Wash, Borrego Canyon Wash and 

Serrano Creek 

Important freshwater drainages to Lower Newport Bay, together covering 49 square miles, 

include the Santa Ana-Delhi Channel, Big Canyon Creek, Bonita Creek, Costa Mesa Channel 

and other local drainages. 
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San Diego Creek is the largest contributor (95%) of freshwater flow into Upper Newport 

Bay, followed by Santa Ana-Delhi Channel (∼5%) (ACOE 2000). Table 1-2 summarizes the 

drainage areas of the major tributaries. 

Table 1-2 Drainage Areas of the Newport Bay Watershed 

Tributary Drainage Area 

(acres) 

Drainage Area 

(%) 

San Diego Creek 47,300 48 

Peters Canyon Wash 28,200 29 

Santa Ana-Delhi 11,000 11 

Other Drainage Areas 12,000 12 

Total 98,500 100 

Upper Newport Bay contains one of the highest quality remaining wetland areas in 

Southern California. The Upper Bay estuary contains a State Ecological reserve in the upper half 

with habitat designated for sensitive species. Sediment capture basins exist in the Upper Bay and 

have been dredged periodically by Army Corps of Engineers (ACOE). Another sediment 

removal/ecological restoration project has been proposed and is currently being evaluated 

(ACOE 2000). Newport Dunes Recreation area—a small public beach—is in the lower portion 

of Upper Bay (outside of the Ecological Reserve) along with more small boat marinas down near 

Pacific Coast Highway Bridge. Historical water uses for Upper Bay included water skiing, 

commercial and sport fishing although it is now used mainly for wildlife habitat, preservation of 

rare species, marine habitat, recreation and shellfish harvesting. In Lower Bay, surrounding 

shores and two islands are highly urbanized with nine boatyards and many (∼10,000) small 

boats. Rhine Channel, a dead-end reach in western side of Lower Bay, is an isolated area with 

poor tidal flushing and minimal storm drain input. The Regional Board has identified Rhine 

Channel as a toxic hotspot based on previous investigations (BPTCP 1997). The entire Newport 

Bay up to the mouth of San Diego Creek is subject to tidal influence. 

Climate is characterized by short, mild winters, and warm dry summers. Average rainfall 

is approximately 13 inches per year. Ninety percent of annual rainfall occurs between November 

and April, with minor precipitation during summer months. San Diego Creek has a mean base 

flow rate of approximately 8 cubic feet per second (cfs) with significant increases (150 to 4000 

cfs) during storm events. San Diego Creek is freshwater with wide range of hardness and small 

influences by the slightly saline water table (less than 1 or 2% salinity). Upper Bay is an estuary 

with saline water conditions during dry weather and yet there is heavy freshwater influx (from 

San Diego Creek and Santa Ana-Delhi Channel) during major storms. Lower Bay waters are 

dominated by twice-daily ocean tides via the jetty entrance, thus saline waters exist at 30 to 35 

parts per thousand (ppt). 

Watershed History 

The description below is taken largely from Regional Board staff report prepared for its 

draft Newport Bay TMDLs (RWQCB 2000). 

The nature of the Newport Bay watershed has changed dramatically over the last 150 

years, both in terms of land use and drainage patterns. In the late 19th and early 20th centuries, 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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land use changed from ranching and grazing to open farming. During this time the Santa Ana 

River flowed into Newport Bay, while San Diego Creek and the small tributaries from the 

Santiago Hills drained into an ephemeral lake and the neighboring area called “La Cienega de las 

Ranas” (Swamp of the Frogs) and then into the River. To accommodate rural farming, the 

ephemeral lake and Swamp of the Frogs were drained and vegetation cleared. Channels were 

constructed (but often did not follow natural drainage patterns) to convey runoff to San Diego 

Creek and then Newport Bay. After a major flood event in 1920’s, the Santa Ana River was 

permanently diverted into the current flood control channel which now discharges to the Pacific 

Ocean. Following World War II, land use again began to change from grazing and open farming 

to residential and commercial development. As urban development in the watershed proceeded 

(and continues), drainages were further modified through removal of riparian vegetation and 

lining of stream banks to expand their capacity and to provide flood protection. These changes 

culminated in the channelization of San Diego Creek in the early 1960s by the Orange County 

Flood Control Department. The channelization isolated the San Joaquin Marsh, the last 

remaining portions of the historic marsh upstream of Upper Newport Bay, from San Diego Creek 

(Trimble 1987). 

Conversion of rural farmland to residential, commercial and light industrial use has been 

constant in the watershed. Land use statistics supplied by Orange County demonstrate this urban 

development (ACOE 2000). In 1983, agriculture accounted for 22% and urban uses for 48% of 

the Newport Bay watershed. In 1993, agricultural uses accounted for 12% and urban uses for 

over 64% of the area. As of 2000, agriculture had dropped to approximately 7% (<7,500 acres), 

including row crops (primarily strawberries and green beans), lemons, avocados and commercial 

nurseries. Currently, San Diego Creek watershed is greater than 90% urbanized whereas Santa 

Ana-Delhi is approximately 95% urbanized. Projected land use suggests 81% urban land use, 

11% open, 8% rural and no agriculture (ACOE 2000). 

Land use and drainage modifications changed the nature and magnitude of toxic 

substance discharges to the Bay. Converting from grazing type agriculture to orchards and row 

crops has increased the amount of pesticide use in the watershed, resulting in discharges of 

pesticides from these areas. The commercial nurseries drain to Peters Canyon Wash via Central 

Irvine Channel and to San Diego Creek via Marshburn Channel and Serrano Creek. Tustin and 

El Toro military bases exist within the watershed and have historically used various toxic 

substances during operations. Both military sites are involved with base closure procedures and 

may ultimately be converted to more urban/suburban areas. Urban development introduced new 

sources of toxic substances, including different insecticides and metals associated with human 

habitation (e.g., buildings, landscaping, and motor vehicles). This continual conversion of 

agricultural land to urban development often includes large construction projects, which may 

release dirt particles laden with legacy pesticides, and possibly yield runoff that contains 

pesticide discharges from the structural and landscape control of pests. 
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Table 1-3 Land Use types in watersheds of Newport Bay 

Land use type San Diego Creek Santa Ana Delhi Newport Bay 

Acres % total Acres % total Acres % total 

Residential 11,668 15.2 5285 18.2 19420 19.7 

Commercial 6381 8.3 2397 8.3 9641 9.8 

Industrial 3965 5.2 1102 3.8 5263 5.4 

Agricultural/ 5092 6.6 0 0 5147 5.2 

Vacant 21,910 28.5 1060 3.7 23,462 23.9 

Education/Religion/

Recreation 

15,811 20.6 825 2.8 17,393 17.7 

No assigned land 

code 

440 0.6 339 1.1 936 0.9 

Transportation 1177 1.5 99 0.3 1326 1.3 

Roads 10,295 13.4 3446 11.9 15,774 16.0 

 

Total 76,739 99.9 29003 100 98,362 99.9 

Source: OCPFRD land use data defined by sub-watersheds to compose each watershed. 

Most accurate and recent land use data provided by OCPFRD GIS Dept., March 1, 2002. 

Public Participation 

The State and EPA have provided for public participation through several mechanisms. 

The Regional Board staff has conducted numerous technical workshops (e.g., quarterly meetings 

since April 2000) on its assessment of toxic pollutant TMDL needs and the specific toxic 

pollutant TMDLs being developed by the State. The Regional Board held several public 

workshops as part of their regular meetings to discuss staff TMDL proposals (January 15, 

September 26, and October 26, 2001). EPA staff provided updates on its TMDL development 

activities at several of these Regional Board meetings. On October 26, 2001, the State’s draft 

organophosphate (OP) pesticide and Selenium TMDLs were presented before the public as part 

of a Regional Board meeting. These draft State TMDLs were also available via the Regional 

Board website after that date. 

On April 12, 2002, EPA publicly noticed the availability of the proposed Toxic Pollutant 

TMDLs and gave the public until May 28, 2002, to provide written comments. A summary of 

the comments received and EPA’s responses will be provided in the Technical Support 

Document—Part J. The EPA notice of availability was published in the Orange County 

Register, mailed to the Basin Plan distribution list provided by the Regional Board, and posted 

on the EPA Region 9 TMDL website. Additionally, EPA is scheduled to present the proposed 

toxics TMDLs to the Newport Bay Watershed Management committee meeting on April 16, 

2002. Public comments on these draft TMDLs should be sent to the following address by May 

28, 2002: 

 Peter Kozelka 

 Monitoring and Assessment Office (WTR-2) 

 EPA Region 9 

 75 Hawthorne Street 

 San Francisco, CA 94105 
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II. Overview of TMDLs and Available Data 

TMDL Components 

This section describes the components of a TMDL and discusses the analytical 

approaches used in the Newport Bay watershed TMDLs to address each component. 

The goal of the TMDL process is to attain water quality standards and protect the 

beneficial uses of water bodies, including aquatic habitat, fishing, and recreation. A TMDL is a 

written, quantitative assessment of water quality problems and contributing pollutant sources. It 

identifies one or more numeric targets (endpoints) based on applicable water quality standards, 

specifies the maximum amount of a pollutant that can be discharged (or the amount of a pollutant 

that needs to be reduced) to meet water quality standards, allocates pollutant loads among 

sources in the watershed, and provides a basis for taking actions needed to meet the numeric 

target(s) and implement water quality standards. 

For federally established TMDLs, seven components are included: 

! Problem Statement—a description of the water body setting, beneficial use impairment 

of concern, and pollutants causing the impairment. 

! Numeric Targets—for each pollutant addressed in the TMDL, appropriate measurable 

indicators and associated numeric target(s) based on numeric and/or narrative water 

quality standards which express the target or desired condition for the water body which 

will result in protection of the designated beneficial uses of water. 

! Source Analysis—an assessment of relative contributions of pollutant sources or causes 

to the use impairment. 

! Loading Capacity/Linkage Analysis—a connection between the numeric targets and 

pollutant sources which yields calculations of the assimilative capacity of the water body 

for each pollutant. 

! TMDL and Allocations— an expression of the total allowable pollutant loads as divided 

between pollutant sources through load allocations for nonpoint sources and wasteload 

allocations for point sources. The TMDL is defined as the sum of the allocations and 

cannot exceed the loading capacity for each pollutant. 

! Margin of Safety—an explicit and/or implicit margin of safety must be specified to 

account for technical uncertainties in the TMDL analysis. 

! Seasonal Variation/Critical Conditions—an account of how the TMDL addresses 

various flows and/or seasonal variations in pollutant loads and effects. 

Problem Statement

 EPA includes problems statements in TMDL documents to assist readers in 

understanding the context for TMDL development and describe the water quality standards 

issue(s) which prompted development of the TMDL. The problem statements identify: 

• name(s) and location(s) of waterbody segments for which the TMDL is being developed, 

• the pollutant(s) for which the TMDL is being developed and information about why the 

pollutant(s) are being addressed, 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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• a description of the water quality impairment or threat which necessitated TMDL 

development, and 

• adequate background information about the watershed setting for the TMDL to help the 

reader understand the key water quality, pollutant discharge, land use, and resource 

protection issues in the watershed. 

As discussed above, California’s Section 303(d) listing decisions only identified general 

 pollutant categories for toxic pollutants impairing waters in the Newport Bay watershed. The 

consent decree identified suspected individual pollutants of concern, but the decree provides that 

TMDLs need not be established for individual pollutants and/or waters if subsequent analysis 

indicates TMDLs are not necessary at this time. To help define the scope of these TMDL studies, 

EPA Region 9, with assistance from the Regional Board, completed an assessment of available 

monitoring data for San Diego Creek and Newport Bay to determine which chemicals warrant 

TMDL development. In our assessment, we reviewed available toxicity and chemical data in 

three critical water quality categories: water column quality, sediment quality, and fish and 

shellfish tissue levels. We applied a two-tiered approach whereby all available data were 

analyzed to determine whether there is clear evidence of impairment with probable adverse 

effects (Tier 1) or incomplete evidence and/or evidence of possible adverse effects (Tier 2) (EPA 

Region 9, 2001). If a chemical exceeded the screening criteria in Tier 1 with respect to any one

of the water quality categories, then it was determined a TMDL is necessary. If a chemical 

exceeded the screening criteria in Tier 2 with respect to two or more categories then a TMDL is 

necessary. We examined monitoring data for the past fifteen years; however, to maximize the 

relevance of our assessment to present-day water quality, we focused on the most recent results 

(since 1995). Our assessment evaluated each chemical identified in the decree for four separate 

water bodies: San Diego Creek, Upper Newport Bay, Lower Newport Bay and Rhine Channel. 

The water body-pollutant combinations for which EPA determined TMDLs are needed at this 

time are listed in Table 1-1. 

The introduction to this document provides a basic discussion of the problems associated 

with exposures to toxic pollutants addressed in these TMDLs and background information on the 

watershed setting. 

Numeric Targets and Applicable Water Quality Standards 

 Numeric targets identify the specific water column, sediment, and/or tissue goals or 

endpoints for the TMDL which equate to attainment of the water quality standards. In some 

cases, multiple indicators and associated numeric target values may be needed to interpret 

applicable water quality standards (e.g. where there is uncertainty that a single indicator is 

sufficient to measure protection of designated uses). In addition, some TMDLs may incorporate 

multiple numeric targets to account for differences in acceptable pollutant levels in a particular 

water body at different time scales (e.g., short term acute toxicity effects versus long term 

chronic exposure effects). 

 Water quality standards are comprised of the designated beneficial uses made of water 

bodies, narrative and numeric water quality criteria (known as “water quality objectives” in 

California, and anti-degradation policies. Applicable standards of concern for these toxic 

pollutant TMDLs include the designated uses and both narrative and numeric water quality 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 13 

criteria, which are applied in a manner which is expected to result in protection of the designated 

beneficial uses. 

 The Regional Board Basin Plan (1995) designates the beneficial uses for Newport Bay, 

San Diego Creek and its tributaries. All water bodies are designated as wildlife habitat, with San 

Diego Creek identified as warm freshwater habitat and Upper and Lower Bay identified as 

estuarine and marine habitat, respectively. The recreation beneficial uses are designated for all of 

Newport Bay and San Diego Creek. Upper and Lower Bay are also designated for commercial 

and sport fishing, preservation of biological habitats—spawning, reproduction, development, 

rare, threatened and endangered species, recreation, and shellfish harvesting. The specific 

beneficial uses of San Diego Creek and Newport Bay are identified in Appendix A-1 at the end 

of this summary document. 

 These toxic pollutant TMDLs focus on two of most sensitive designated aquatic life and 

wildlife beneficial uses of concern in the watershed—RARE and WILD. One primary objective 

is to protect the special biological and wildlife habitat of the Newport Bay Nature Preserve and 

Ecological Reserve, in the upper part of Upper Newport Bay. The Nature Preserve is considered 

a critical estuary of Southern California. The Upper Newport Bay Nature Preserve consists of 

approximately 1,000 acres of open space and is home to seven rare or endangered bird species: 

Light-footed clapper rail, Belding's savannah sparrow, least tern, brown pelican, peregrine 

falcon, black rail, and California gnatcatcher. Two endangered plants, the salt marsh birds-beak 

and the rare Laguna live-forever, are also found at the reserve. The second objective is to reduce 

build up of toxicants in fish and shellfish within all water bodies, thereby minimizing adverse 

impacts associated with wildlife and human consumption of contaminated food. Seventy-eight 

species of fish inhabit the Upper Newport Bay waters, including the California halibut and 

barred sand bass—two popular sport fishes. 

 Narrative water quality objectives considered for each TMDL are specified by the 1995 

Regional Board Basin Plan: 

• Toxic substances shall not be discharged at levels that will bioaccumulate in aquatic 

resources to levels which are harmful to human health; 

• The concentrations of toxic substances in the water column, sediments or biota shall not 

adversely affect beneficial uses. 

 Numeric water quality objectives for several pollutants addressed in these TMDLs were 

promulgated by EPA in 2000 in the California Toxics Rule (CTR). Pollutants covered by CTR 

objectives include selenium, cadmium, copper, lead, zinc, chromium, chlordane, dieldrin, DDT, 

toxaphene and PCBs. The CTR did not establish numeric objectives for chlorpyrifos, diazinon, 

or mercury, and the selenium and cadmium objectives were established contingent on an EPA 

commitment to revise the objectives promptly to better protect wildlife. 

 In many cases where applicable standards are expressed in numeric terms, it is 

appropriate to set the numeric target equal to the numeric water quality standard. For most 

metals addressed in these TMDLs, the numeric targets are equal to the numeric objectives in the 

CTR. For selenium (Se) the freshwater and saltwater water quality standards are defined by 

CTR. However, EPA acknowledged in its consultations with the U.S. Fish and Wildlife Service 

(USFWS) that the freshwater standards for Se may not be fully protective of wildlife, and EPA 

committed to revisit and, if necessary, revise the Se criteria in the near future. In its draft TMDL 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 14 

for Se, the Regional Board proposed to apply more protective Se targets based on USFWS 

recommendations. Therefore, EPA is proposing TMDLs based on the promulgated CTR 

standards, but is inviting comment on the alternative approach of basing the Se TMDLs on the 

more protective targets proposed by the Regional Board. (See section IV—Se TMDL for 

further discussion.) 

 In some cases, it is necessary to interpret a numeric standard in terms other than the 

method through which the standard is expressed as long as the target(s) can be shown to relate 

back to achieving the water quality standard(s). For some pollutants (e.g., bioaccumulative 

toxins) or receiving water settings (e.g. embayments), it makes more sense from the standpoint 

of source control and impact assessment to focus the TMDL on reductions of pollutant mass 

loads than solely on avoidance of exceedences of concentration-based standards. Moreover, use 

of sediment and/or fish tissue endpoints may provide more discriminating indicators of the 

beneficial use impacts of concern in a TMDL (e.g., pollutant bioaccumulation in the food chain 

and resultant human health or aquatic life impacts from consumption of contaminated 

organisms). 

 For several pollutants addressed in these TMDLs for which numeric objectives are in 

place (mercury, chromium, chlordane, dieldrin, DDT, toxaphene, and PCBs), the numeric targets 

are expressed in terms of protective sediment or fish/shellfish tissue levels. EPA’s analysis of 

the relationship between the levels of these pollutants found in the water column, sediment, and 

fish/shellfish tissue found that attainment of the sediment and fish/shellfish tissue numeric targets 

will result in attainment of the water column numeric objectives. It appears that the sediment 

and tissue numeric targets may be somewhat more protective than the numeric objectives for 

these pollutants although the accuracy of translators between these media is somewhat uncertain. 

The use of sediment and tissue targets is appropriate in these cases in order to provide an implicit 

margin of safety to account for uncertainties in the relationship between pollutant loadings and 

beneficial use effects, and to ensure that all applicable standards are attained. In addition, EPA’s 

decision to use sediment quality and fish tissue values as numeric targets for these pollutants is 

based in part on the fact that these substances are much more likely to be associated with 

particulate matter than to remain in the dissolved phase; that is, these compounds are either 

sorbed to bottom sediments or associated with extremely fine suspended sediments. Also, there 

are technological challenges accompanied with sampling and accurately detecting these 

compounds in water column samples. Therefore, these pollutants are unlikely to be detected in 

the water column in dissolved form even in waters where they may be present at levels of 

concern. 

 In situations where applicable water quality standards are expressed in narrative terms, it 

is necessary to develop a quantitative interpretation of narrative standards. Since a TMDL is an 

inherently quantitative analysis, it is necessary to determine appropriate quantitative indicators of 

the water quality problem of concern in order to calculate a TMDL. It is sometimes possible to 

supplement water column indicators (i.e., pollutant concentrations in water) with measures in 

sediment or tissue media since these alternative indicators are more directly associated with the 

pollutant effects of concern. 

Where sediment indicators are used in these TMDLs, they are based on sediment quality 

guidelines developed by the Florida Department of Environmental Protection (MacDonald et al 

1996). Where fish or shellfish tissue indicators are used, they are based on tissue screening 

values established by EPA (EPA 2000d and EPA 2000e), the California Office of 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 15 

Environmental Health Hazard Assessment (OEHHA, 1999), or the New York Department of 

Environmental Conservation (NY DEC 1994; 1998). The specific basis for these target 

indicators is discussed in the individual TMDL descriptions. 

For the organophosphate (OP) pesticides, chlorpyrifos and diazinon, there are no 

promulgated water quality criteria established by EPA or the State of California. Several entities 

including EPA (USEPA 2000b and c) and California Department of Fish and Game (CDFG 

2000a) have recommended criteria values for these pollutants. To be protective of aquatic 

resources and to meet beneficial uses, EPA has selected the lowest recommended values (as 

provided by either EPA or CDFG) for chlorpyrifos and diazinon. 

 Source Analysis

 An understanding of pollutant loading sources and the amounts and timing of pollutant 

discharges is vital to the development of effective TMDLs. These TMDLs provide estimates of 

the amounts of pollutants entering the receiving water of concern or, in some cases, the amount 

of pollutant that is bioavailable based on historic loadings stored in the aquatic environment. 

These pollutant source estimates are documented based on data analysis and modeling studies 

described in the individual TMDLs and associated TSDs. Source loading estimates can be 

categorized in many ways, including but not limited to discharge source, land use category, 

ownership, pollutant production process (e.g. sedimentation processes), and/or tributary 

watershed areas. 

 The source analysis for these TMDLs indicated that historical discharges of PCBs and 

chlorinated pesticides, all of which are no longer authorized to be used, are believed to be 

primarily responsible for the pollutant levels measured in Newport Bay. Metals loading is 

associated with historical and ongoing discharges of urban runoff. Selenium loadings are 

estimated to come primarily from natural runoff and discharges of shallow groundwater. 

Discharges of OP pesticides are associated with past and ongoing uses of these pesticides for 

household and agriculture pest control. Some pollutant loads are also estimated to come from 

seawater and atmospheric deposition. 

The individually permitted point sources listed below discharge into waters in the 

Newport Bay watershed. No sewage treatment plants discharge effluent into water bodies of 

Newport Bay. Some individual permits may be affected by San Diego Creek TMDLs, others by 

Newport Bay TMDLs or a few not at all. A general permit is in place to regulate discharges 

associated with groundwater cleanup, which affects 21 permittees and focuses principally upon 

total suspended sediment, petroleum hydrocarbons and chlorinated solvents. Another general 

permit is in place which regulates groundwater dewatering operations of 12 permittees and 

focuses principally on suspended sediment discharges. Runoff from state highways is regulated 

through the statewide CalTrans permit. 

 Six boatyards are located around Newport Bay; all are regulated for indirect metals 

discharges to the sewer system. Discharges from these boatyards do not flow to the Bay. 

Instead, wastewater flows into sumps or into connections to the Orange County Sanitation 

District pre-treatment system. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Table 2.1: NPDES Permits In San Diego Creek/Newport Bay Watershed 

Individual NPDES permits in San 

Diego Creek watershed:Name 

Comments 

Orange County Stormwater Includes many cities as co-permittees 

John Wayne Airport Stormwater runoff flows into Santa Ana-Delhi 

Channel, therefore this source is addressed in 

Newport Bay TMDLs (but not TMDLs for San Diego 

Creek) 

Tustin Marine Base/GW general At present this is general permit, although RWQCB 

is currently drafting an individual permit 

Silverado Constructors/GW cleanup TSS under emergency conditions only 

Irvine Ranch Water District Discharges tertiary treated water into Sand Canyon 

Reservoir and permit regulates stormwater overflows 

from Sand Canyon Reservior 

Serrano Water Treatment Plant this is a drinking water filtering plant 

City of Tustin groundwater desalter Irregular discharges 

Great Lakes Chemical/GW cleanup No longer discharges 

The Regional Board currently regulates three commercial nurseries through waste 

discharge requirements (WDRs): Bordier’s, Hines and El Modeno Gardens. These nurseries are 

located in the upper reaches of the watershed, and their discharge (normally only during storm 

events) flows into Peter’s Canyon Wash before reaching the main stem of San Diego Creek. The 

Regional Board is currently evaluating whether WDRs are needed for two other nurseries 

(Nakase Nursery and AKI nursery). There are some unpermitted nurseries that are smaller in 

size than the permitted nurseries. Runoff from other agricultural operations in the watershed, 

including row crops, orchards, and vineyards, is not currently regulated. 

Loading Capacity/ Linkage Analysis 

 The loading capacity is the critical quantitative link between the applicable water quality 

standards (as interpreted through numeric targets) and the TMDL. The loading capacity reflects 

the maximum amount of a pollutant that may be delivered to the water body and still achieve 

water quality standards. The linkage analysis investigates the relationship between pollutant 

loadings and water quality effects in order to calculate loading capacities for each pollutant and 

water body. The loading capacity sections discuss the methods and data used to estimate loading 

capacity. A range of methods were used to derive the loading capacities for the various 

pollutants, including predictive water quality models and linkage methods based principally on 

data analysis. The individual TMDLs and associated TSDs describe the linkage analysis in 

detail. 

TMDLs and Allocations 

 For each pollutant and water body, this document identifies the necessary TMDLs (total 

allowed pollutant amount) and its components: appropriate wasteload allocations for point 

sources and load allocations for nonpoint sources and natural background. The TMDLs and 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 17 

associated wasteload and load allocations are expressed in quantitative terms as required by 

federal regulations. 

TMDL calculation methods are summarized in this document and described in greater 

detail in the TSDs. Separate wasteload and load allocations are identified for point and nonpoint 

sources, respectively. In cases where it is feasible, individual wasteload allocations are 

established for each existing point source discharge, including permitted stormwater discharges. 

 Load allocations for nonpoint sources may be expressed as specific allocations for 

specific dischargers or as “gross allotments” to nonpoint source discharger categories. TMDLs 

usually provide separate load allocations for natural background loads. Separate load allocations 

for background loads are calculated for metals. Separate background allocations are 

inappropriate for pesticides and organochlorine compounds because they of anthropogenic 

origin. Separate background allocations could not be calculated for selenium, chromium and 

mercury because insufficient information was available to support these calculations. 

Background levels of selenium associated with groundwater inputs to surface water may be 

significant; however, the physical and hydrological structure of the watershed has been highly 

altered as a result of hydrologic modifications, groundwater pumping, irrigation practices, and 

water imports to the watershed. As a result, it would be very difficult to estimate “naturally 

occurring” selenium discharge levels. Background levels of chromium and mercury are not 

expected to be substantial. 

 Allocations may be based on a variety factors. Federal regulations do not establish 

specific criteria which must be considered in dividing and allocating any available loading 

capacity between contributing sources. Pollutant specific allocation schemes are proposed in 

these TMDLs; EPA is willing to consider alternative ideas and invite comments that include 

rationale. Criteria applied to determine the division of available pollutant loading capacity 

include: 

• Organophosphate Pesticides: All allocations are concentration-based and are applied 

equally to all discharge sources. 

• Selenium: Allocations were generally divided in proportion to land use areas of the 

different allocation categories for nonpoint sources and in proportion to discharge flow 

rates for point source categories. Consideration of flow rates in freshwater bodies, 

directly linked to precipitation events, is included. 

• Metals: Allocations were divided in proportion to the total estimated existing loads 

associated with each source category. 

• Organochlorine Compounds: Allocations to watershed sources were generally divided in 

proportion to land use areas of different allocation categories, with some consideration 

of the feasibility of reducing loads for DDT. Allocations between watershed sources 

and in-Bay sediment sources were divided in proportion to the percentage of total loads 

associated with watershed versus in-Bay sediment sources. 

• Mercury and Chromium: Allocations to watershed sources were generally divided in 

proportion to land use areas of different allocation categories. Allocations between 

watershed sources and in-Bay sediment sources were divided in proportion to the 

percentage of total loads associated with watershed versus in-Bay sediment sources. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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 TMDLs (and thus, load allocations and wasteload allocations) can be expressed as “mass 

per time, toxicity, or other appropriate measure”, depending on the type of waterbody and the 

sources that contribute to impairment. The TMDLs for all pollutants except diazinon and 

chlorpyrifos are expressed in terms of mass loads per time, and the TMDLs for the pesticides 

diazinon and chlorpyrifos are expressed in terms of water column concentrations. It is 

appropriate to express these pesticide TMDLs in terms of water column concentrations because 

these pollutants cause adverse effects on aquatic life through relatively short term exposures. 

These pollutants are relatively short-lived in the environment before they break down into less 

toxic forms, and they do not bioaccumulate through the food chain in the same way several of 

the other pollutants addressed in these TMDLs do. Therefore, the water column concentrations 

of these pesticides are of greatest concern in preventing adverse ecosystem effects. 

Margin of Safety 

 A margin of safety is incorporated in each TMDL analysis in order to account for 

uncertainty in the relationship between pollutant loads and water quality effects. 

 The margin of safety can be implicit (i.e., incorporated into the TMDL analysis through 

conservative assumptions) or explicit (i.e., expressed in the TMDL as a portion of the loadings) 

or a combination of both. The TMDLs described in this document include a margin of safety 

discussion for each pollutant that describes the basis for the provided margin of safety and shows 

why it is adequate to account for uncertainty in the TMDL. The document discusses sources of 

uncertainty in the analysis and how individual analytical assumptions or other provisions 

adequately account for these specific sources of uncertainty. 

 For all pollutants except metals, a 10% explicit margin of safety was applied to account 

for uncertainties in the analysis. An explicit margin of safety is appropriate for each TMDL 

because there is significant uncertainty in the analysis of pollutant effects, loads, fate (i.e. 

chemical transformations and degradation following discharge), and transport in the watershed. 

The data supporting the TMDLs were somewhat limited. For metals, a 20% explicit margin of 

safety was applied to account for (1) these analytical uncertainties and (2) the consideration that 

the metals TMDLs are expressed in terms of dissolved metals although it is likely that total 

metals loading levels are somewhat higher than dissolved metals loads, and that total metals 

loads may be of concern as a cause of sediment toxicity. 

For all pollutants, the TMDLs also incorporate an implicit margin of safety because 

numerous conservative assumptions were made to ensure that the analytical methods applied are 

environmentally protective. Each TMDL section describes sources of uncertainty in the analysis 

and the assumptions made which provide an implicit margin of safety. 

Seasonal Variations and Critical Conditions 

 TMDL must describe the methods used to account for seasonal variations and critical 

conditions (e.g., stream flows, pollutant loadings, and other water quality parameters) in the 

TMDL(s) [40 CFR 130.7 (c)]. In the semi-arid climate of Southern California there are two 

seasons—dry weather during most of the year and intermittent wet weather events typically 

between November and March. This two-season climate creates significant differences in flow 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 19 

through the creeks and streams. In general, 90% of the water flow occurs during less than 10% 

of the time; that is, most significant storm events and associated high flows usually occur during 

the months of December, January and February. 

 EPA has utilized two different approaches to seasonal variations and critical conditions in 

developing these TMDLs. One approach varies TMDLs on a seasonal basis. For example, the 

OP pesticide TMDLs (chlorpyrifos and diazinon) show there is considerable increase in 

pesticides applied during the dry season (when pests grow and create problems); however, 

aquatic impairment occurs during wet weather events as surface runoff pollutes the freshwater 

tributaries. OP pesticide critical conditions are explained more in section III below. 

 The other approach to addressing seasonal variations and critical conditions is to define 

critical conditions solely based on freshwater flow rates due to precipitation regardless of season. 

This flow based approach is applied to freshwater loading to metals, Se, and organorchlorine 

(OC) compounds. Unlike the OP pesticides, the water quality effects associated with these 

pollutants are not expected to vary on a seasonal basis. In this flow-based approach, the 

continuous range of stream flows (measured as daily flow rates) that occur in San Diego Creek is 

broken down into several flow tiers. The loading capacity for each breakpoint in the flow tiers is 

established, and the sum of allowable loads under all tiers equals the total annual loading 

capacity for freshwater bodies. Thus the applicable allocation for a given source does not 

depend on the time of year, but on the actual stream flow (or associated sediment deposition rate 

for OC compounds) at the time of discharge. This flow approach is partially used for chromium 

and mercury TMDLs for Rhine Channel, where freshwater has little influence (6%) on 

deposition within that dead-end reach of Newport Bay. 

 To estimate the loading capacity of freshwater systems, EPA has utilized daily flow 

records at San Diego Creek at Campus Drive which were collected by Orange County Public 

Facilities and Resource Department (OCPFRD). This data spans July 1985 to June 2000; 

unfortunately OCPFRD flow records for 1995 to 1996 do not exist (pers. commun., L. Waldner). 

For calculating the flow based approach to Se and dissolved metals TMDLs, EPA used annual 

flow records for water year 1995, 1997, 1998, 1999, 2000. This time span covers a reasonable 

diversity of rainfall conditions based on precipitation measurements from 1958 to 2000. That is, 

it includes the exceptionally wet El Nino year, 1998, as well as relatively drier years, 1999 and 

2000. Table 1-4 shows rainfall recorded at Tustin/Irvine Ranch gage station for each year within 

the time span utilized by EPA, as well as historical high and low rainfall records. These data 

illustrate that the data years used by EPA for this approach are reasonably representative of the 

entire time period. Technical Support Document—Part B gives more explanation of freshwater 

flows and seasonal variations. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 20 

Table 1-4 Annual Precipitation Records at Tustin/Irvine Ranch 

Water 

year* 

Annual 

Rainfall 

(inches) 

Water 

year* 

Annual 

Rainfall 

(inches) 

comment 

1985 10.3 1995 24.7 

1986 14.4 1996 11.2 

1987 8.8 1997 16.2 

1988 11.1 1998 34.7 

1989 8.2 1999 8.6 

1990 5.9 2000 8.8 

1991 11.2 2001 14.6 

1992 17.2 1960--2000 13.3 Annual average 

1993 27.1 1961 4.1 Minimum value 

1994 10.2 1998 34.7 Maximum value 

Source: OCPFRD 

*for example the water year 1997 includes July 1996 to June 1997. 

Available Data 

Monitoring data used in these TMDLs came from numerous sources. Much of the 

analysis has been summarized in a Regional Board staff report describing the monitoring results 

in relation to water quality objectives, sediment guidelines and fish tissue screening values 

(SARWQCB, 2000). EPA has included data from a few more recent studies and focused on 

monitoring results compiled over the past five years to assess present day water quality 

conditions. EPA has also reviewed ten years of sediment data and nearly twenty years of fish 

tissue results to determine long-term trends. Finally, the Regional Board has several projects 

currently in progress with the Southern California Coastal Research Water Project (SCCWRP). 

The most relevant studies to these toxics pollutant TMDLs address sediment toxicity in Newport 

Bay (2001a), fish bioaccumulation in Newport Bay (2001b) and freshwater toxicity in San Diego 

Creek at Campus Dr. (2001c). Preliminary results for two studies (2001a, 2001b) were available 

as of Dec 1, 2001 and (where feasible) some data were included in these TMDLs. A summary of 

all monitoring data, the waterbodies sampled, measured parameters and citation/abbreviation is 

provided in Table 2-2. 

Table 2-2 Overview of monitoring data 

Organization Period of 

record

Geographic 

Scope

Measured 

Features

Measured

Parameters and comments

Lee & Taylor

(2001a) 

319(h) report 

(for SA RWQCB) 

Winters 

1999; 

2000 

San Diego Creek 

Watershed 

stormwater runoff Se; metals and OP pesticides in 

watershed, 

Draft report provided May 2001 

Hibbs & Lee

Se Study 

1999 San Diego Creek; 

Groundwater 

Surface and 

groundwater 

Se in groundwater and SDCreek 

Lee & Taylor 

(2001b) 

205(j) report 

(for SA RWQCB) 

1997-‘99 San Diego Creek 

Watershed 

Surface water 

toxicity 

Toxicity and pesticides in 

watershed 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 21 

CDPR Red 

Imported Fire Ant

(RIFA) study

1999-

present 

San Diego Creek 

Watershed 

Surface water Toxicity and pesticides Insecticides 

and OP pesticides in watershed; 

toxicity and chemical 

concentrations 

IRWD (1999) 

database

Fall 1997 

--March 

1999 

San Diego Creek; 

Upper and Lower 

Bay 

(10 sites) 

Surface water; 

sediments 

metals and organics using 

appropriate sampling and analytical 

techniques, one day composites, 

year round, no storm events 

OCPFRD (2000) 

(NPDES annual 

report) 

1996-

2000 

All freshwater 

tributaries, San 

Diego Creek; Upper 

and Lower Bay, 

Rhine Channel 

Surface water; 

sediments 

7 metals, some organics, dry and 

wet weather events; some four 

consecutive day sampling; semiannual sediment data 

Orange County 

Coastkeeper 

(1999) 

Oct. 1999 Rhine Channel (2 

sites); 

Lower Bay (1 site) 

Sediments Metals, sediment core in Rhine 

Ogden Env. (1999, 

for City of Newport 

Beach) 

June 1999 Lower Bay 

(12 sites) 

Sediment Metals; few priority organics in 

dredge studies 

BPTCP (1997) 

(for SWRCB/ 

NOAA/EPA) 

1994; ‘96 Upper and Lower 

Bay 

(18 sites total) 

Sediment triad 

study 

Metals; many organics; toxicity; 

benthic comm. Index 

Bight ’98 

(coordinated by 

SCCWRP) 

1998 Lower Bay 

(11 sites; 

not Rhine). 

Sediment triad 

study 

chemistry; toxicity; benthic comm. 

index; interstitial porewater data 

for AVS & SEM 

Cal. Dept. 

Fish & Game 

1999-

2000 

San Diego Creek 

watershed 

Sediment; Fish 

tissue 

OP Pesticides; insecticides in 

sediment and fish tissue as part of 

Red Fire Ant project 

Calif. Fish 

Contamin. Study 

(CFCS) (for 

SWRCB/ OEHHA) 

1999–

2000 

Upper and Lower 

Bay 

(sport) Fish tissue Preliminary results for three 

metals; many organics in fish fillets 

with skin off 

State Mussel 

Watch (SMW) 

(for SWCRB) 

1980-

2000 

mostly Upper and 

Lower Bay 

Shellfish 

tissue 

Metals; organics in resident or 

transplanted mussels, no recent 

data in SDC 

Toxic Substance 

Monitoring 

(TSM) 

(for SWRCB) 

1983–

1998 

all Newport Bay 

waterbodies 

Fish 

tissue 

Total metals; organics in whole fish 

with skin on 

SCCWRP (2001a)

Sediment Toxicity 

Study 

(for SA RWQCB) 

On-going Upper and Lower 

Bay; including 

Rhine Channel 

(10 sites) 

Sediment; Water 

Toxicity 

chemistry; toxicity; benthic comm. 

index, some preliminary results 

available 

SCCWRP (2001b)

Fish Study 

(for SA RWQCB) 

On-going Upper and Lower 

Newport Bay 

Fish tissue Four metals; priority organics, 

sportfish samples in 2001; 

ecological risk samples in 2002 

SCCWRP (2001c) 

Freshwater Study 

(for SA RWQCB) 

On-going San Diego Creek 

(1 site) 

Freshwater 

Toxicity 

TIEs for metals in Winter 2002; Se 

bioaccumulation study 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 22 

III. Organophosphate (OP) Pesticide TMDLs 

TMDLs are required for chlorpyrifos and diazinon for San Diego Creek. To address 

impairment specified in the 1998 Section 303(d) list, the TMDLs for San Diego Creek address 

both Reach 1 and Reach 2, unless otherwise explicitly indicated. A TMDL is also required for 

chlorpyrifos in the Upper Newport Bay. TMDLs are required despite recent re-registration 

agreements to phase out certain uses of these two OP pesticides by 2006 (EPA 2001b, 2000b). A 

large portion of information presented here and in the Technical Support Document—Part C is 

based on the OP Pesticide draft TMDLs written by Regional Board staff (SARWQCB, 2001a). 

Problem Statement 

San Diego Creek 

Water column acute and chronic toxicity to aquatic life in San Diego Creek and its tributaries has 

been identified and attributed largely to diazinon and chlorpyrifos through toxicity identification 

evaluation (TIE) studies. Over 300 toxicity tests have been performed on 123 water samples 

collected from the Newport Bay watershed. Toxicity occurred during virtually all monitored 

storm events and is viewed primarily as a wet weather problem. Dry weather toxicity was 

generally confined to upper reaches of the watershed (near the foothills) and diluted or otherwise 

remediated in downstream locations (Lee and Taylor 2001a; b). These TMDLs are structured to 

prevent toxicity under all flow conditions.

Average diazinon concentrations in surface waters of San Diego Creek have exceeded the 

freshwater chronic numeric target of 50 ng/L both during baseflow (200 ng/L) and during 

stormflow (445 ng/L). Average chlorpyrifos concentrations in San Diego Creek have exceeded 

the freshwater chronic numeric target of 14 ng/L during baseflow (111 ng/L) and stormflow (87 

ng/L). 

Upper Newport Bay 

Evidence exists indicating water column toxicity due to chlorpyrifos in Upper Newport 

Bay. This is restricted to storm events when freshwater inputs from San Diego Creek and Santa 

Ana Delhi linger in the Upper Bay (Lee and Taylor 2001a;b). Average chlorpyrifos 

concentrations in surface waters of Upper Newport Bay have exceeded the saltwater chronic 

numeric target of 5.6 ng/L during stormflow conditions (43.3 ng/L). Toxicity attributed to 

chlorpyrifos does not extend into Lower Bay. Diazinon does not appear to cause toxicity in 

saltwater bodies such as Upper or Lower Newport Bay 

Bioaccumulation 

In San Diego Creek watershed, fish tissue concentrations of chlorpyrifos have 

consistently remained orders-of-magnitude below the OEHHA screening value (10,000 ppb) for 

fish consumption. Diazinon fish tissue concentrations have exceeded the OEHHA screening 

value of 300 ug/kg only once (440 ug/kg), according to Toxic Substances Monitoring data. 

Mussel tissue concentrations of both OP pesticides have never exceeded the OEHHA screening 

values. Therefore, there is no compelling evidence of bioaccumulation of these substances to 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 23 

levels of concern, an observation consistent with monitoring from other studies (CDFG 2000, 

EXTOXNET). 

In short, there is conclusive evidence that diazinon and chlorpyrifos are causing acute and 

chronic toxicity in San Diego Creek and that chlorpyrifos causes toxicity in Upper Bay. Toxicity 

predominantly occurs during storm events and certainly affects lower level aquatic organisms 

such as Ceriodaphnia (Lee and Taylor 2001a, 2001b). Adverse impacts may also be affecting 

fish survival and reproduction. 

Numeric Targets 

At present, there are no promulgated water quality criteria for chlorpyrifos and diazinon. 

For these TMDLs, EPA has selected the numeric targets from the recommended acute and 

chronic criteria derived by the California Dept. of Fish and Game for chlorpyrifos and diazinon 

in freshwater (CDFG 2000a) and by EPA for saltwater (USEPA 1986). These numeric targets 

serve as the quantitative interpretation of the narrative water-column quality objective as 

specified in the Basin Plan (1995). These numeric targets will be protective of aquatic life in San 

Diego Creek and Upper Newport Bay and sufficient to remove impairment caused by OP 

pesticide toxicity. The selected targets are the most conservative numeric values for these two 

OP pesticides. Target concentrations are shown in Table 3-1; saltwater chronic and acute targets 

for diazinon are not applicable since TMDLs are not required for this pollutant in any of the 

saltwater bodies covered by these TMDLs. 

Table 3-1 Selected Numeric Targets 

 Concentration (ng/L) 

Pesticide Criterion Freshwater1 Saltwater2

Diazinon Chronic 50 N/a 

Diazinon Acute 80 N/a 

 

Chlorpyrifos Chronic 14 5.6 

Chlorpyrifos Acute 20 11 

 

1 from Calif. Fish & Game (2000a) 

2 from EPA (1986) 

 chronic means 4-consecutive day average 

Source Analysis 

This section of the TMDL presents a synopsis of the major sources of diazinon and 

chlorpyrifos to San Diego Creek and chlorpyrifos to Upper Newport Bay. This synopsis focuses 

on water column concentrations from several studies conducted in the watershed targeting 

aquatic life toxicity associated with pesticides (Lee and Taylor 2001a; 2001b; DPR studies). 

These studies were not detailed enough to identify discrete sources, but it appears that diazinon 

and chlorpyrifos are problems attributed to agricultural and residential use. Investigations of 

DPR pesticide use reports provide some estimates of pesticide applications by land use within 

the watershed; however this does not comprehensively depict all sources in San Diego Creek. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 24 

Additional analysis via land use information indicates that residential contributions are also 

significant. The synopsis is presented below, whereas the reader will find a more complete 

source analysis in the Technical Support Document--Part C. 

Diazinon 

Within freshwater bodies of San Diego Creek, monitoring results show extremely high 

detection frequency (>98%) of diazinon during storm events. This detection frequency decreases 

slightly (89%) during dry weather or base flow conditions. Table 3-2 summarizes monitoring 

results by water body groups such as San Diego Creek Reaches 1 and 2, Peter’s Canyon Channel 

and Upper Newport Bay. Maximum concentrations were observed in Hines Channel (which 

drains into Peters Canyon Channel, and is tributary to San Diego Creek Reach 1). 

At virtually all the locations, the median stormflow concentration is significantly higher 

than the median baseflow concentration. Since stormwater runoff constitutes about 80% of the 

volume of water discharged to Newport Bay on an annual basis, this would indicate that the 

overwhelming majority of the pesticide load would derive from stormflow rather than baseflow. 

The average concentration is actually higher for baseflow, but this is biased by a few very high 

detections from 1998 near nurseries. These results have not been observed in later sampling and 

the nurseries have subsequently instituted measures targeted at reducing pesticide runoff. 

Chlorpyrifos 

Chlorpyrifos was detected less frequently (in 45% of samples) than diazinon. This is due 

in part, to the lower solubility of chlorpyrifos, and its greater affinity for sediment. The lower 

mobility of chlorpyrifos results in lower concentrations in the drainage channels. According to 

DPR Pesticide use database, over twice as much chlorpyrifos is applied as compared to diazinon 

(per pound of active ingredient). 

Sample locations monitoring residential areas tended to have lower chlorpyrifos 

concentrations. Chlorpyrifos was not detected at three of the residential locations under both 

baseflow and stormflow conditions. The detection frequency, and maximum concentrations 

detected at another partly residential location (Santa Ana Delhi Channel) were low. The only 

residential site with relatively high chlorpyrifos concentrations was Westcliff Park (stormflow), 

but the baseflow concentrations were relatively low. 

The average values for stormflow and baseflow exceed the freshwater chronic numeric 

target (14 ng/L). Within the drainage channels, 44% of the chlorpyrifos results exceeded the 

chronic target. In the Upper Bay, 92% of the samples were above the saltwater chronic numeric 

target of 9 ng/L. 

California DPR Pesticide Use Database 

The California Department of Pesticide Regulation (DPR) Pesticide Use database 

provides information by county about application of pesticides by various licensed pesticide 

users. For the Newport Bay watershed, diazinon and chlorpyrifos applications have been 

estimated to comprise one-fifth the total reported for Orange County (because the watershed 

acreage is one-fifth that of Orange County). In addition, land use analyses indicate that 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 25 

commercial nurseries and residential areas are associated with high pesticide application rates, 

and much higher detection in water during wet weather. Urban uses account for over 90% of 

total diazinon and chlorpyrifos use in the Newport Bay Watershed, with residential use by 

homeowners accounting for roughly half the estimated total of 10,700 lbs of diazinon and 24,000 

lbs of chlorpyrifos used in the watershed in 1999. Similar studies reported in literature of 

pesticide use and water monitoring results have indicated that residential hotspots (individual 

homes) can account for most of the diazinon runoff from a neighborhood (Scanlin and Feng 

1997; Cooper 1996). 

Based on data from investigations carried out from 1996-2001, about 32 pounds of 

diazinon are discharged annually to San Diego Creek, mostly during storm events. This is less 

than 0.3% of the estimated diazinon mass annually applied in the watershed. About 7 pounds of 

chlorpyrifos are annually discharged to Upper Newport Bay, with most of the load delivered 

during storm events. This amounts to about 0.03% of the estimated annually applied 

chlorpyrifos mass. Available data and studies indicate that in normal use, OP pesticides break 

down quickly and therefore only a small percentage of the total amount applied is available to 

runoff to waterbodies. However, even small amounts of these pesticides are enough to cause 

acute and chronic toxicity in receiving water bodies. 

In summary, surface runoff is the source of virtually all the loadings. Contributions from 

atmospheric deposition, sediment remobilization, and groundwater are negligible, and the 

chemical properties of diazinon and chlorpyrifos ensure that they do not accumulate in the 

environment. Runoff derived from urban land uses accounts for about 88% of the diazinon 

baseflow load, and 96% of the stormflow load. Agricultural sources (including nurseries) 

account for the remainder of the load. For chlorpyrifos, runoff derived from urban land uses 

accounts for about 85% to 88% of the baseflow and stormflow loads, while agriculture 

(including nurseries) accounts for about 12% to 15% of the load. On a per acre basis, different 

land uses contribute diazinon and chlorpyrifos runoff at fairly equal rates within the watershed 

and distinct source areas are not readily identifiable. Median concentrations from 14 sampled 

drainage channels across the watershed did not exhibit large differences. 

Although it appears that some of the nursery/agricultural locations yield higher 

chlorpyrifos concentrations than the residential areas, it should be noted that the nursery 

monitoring locations are selected to monitor undiluted nursery discharge, very close to where the 

chlorpyrifos is used. In contrast, runoff from individual homes where chlorpyrifos is applied is 

not monitored; rather the monitoring location is further away within a channel thereby collecting 

mixed/diluted runoff from many homes. In addition, because of the inherent immobility of 

chlorpyrifos, and its tendency to adsorb to sediment, higher chlorpyrifos concentrations are most 

likely to be encountered in areas nearby to where it is applied, before it partitions out of the 

aqueous phase and settles out along with the sediment. 

Loading Capacity/Linkage Analysis 

These OP pesticide TMDLs use a concentration-based loading capacity and allocations 

for diazinon and chlorpyrifos. The concentration-based loading capacity will address the 

problems of aquatic toxicity within the watershed and Upper Newport Bay. Because diazinon 

and chlorpyrifos are generally not known to bioaccumulate, there is no need to establish the 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 26 

loading capacity via mass based or toxic units. These concentration-based TMDLs will protect 

aquatic life from short-term exposure via acute targets and long-term exposure via chronic 

targets. 

The concentration-based loading capacity values are exactly the same as those selected as 

the numeric targets (see Table 3-1). For San Diego Creek, the loading capacity for diazinon has 

two components: the chronic or 4-day average concentration (50 ng/L), and a maximum 1-hour 

average (acute) concentration of 80 ng/L. The loading capacity for chlorpyrifos in San Diego 

Creek also has two components: the chronic or 4-day average concentration (14 ng/L), with a 

maximum 1-hour average (acute) concentration of 20 ng/L. For Upper Newport Bay, the loading 

capacity for chlorpyrifos has two components: the chronic or 4-day average concentration (5.6 

ng/L), and a maximum 1-hour average (acute) concentration of 11 ng/L acute. 

As discussed above regarding the numeric targets, this loading capacity (including the 

margin of safety discussed below) will result in achievement of the narrative water quality 

objective for aquatic toxicity because these numeric targets arise from aquatic toxicity tests 

completed during the development of these recommended water quality levels. 

TMDL and Allocations 

The TMDLs for diazinon and chlorpyrifos are being established at levels equivalent to the 

loading capacities identified above. We have also utilized concentration-based allocations for 

both wasteload allocations (WLA) and load allocations (LA). 

For these OP pesticide TMDLs, EPA has established an explicit (10%) margin of safety 

(discussed below); therefore the concentration-based allocations are calculated as 90% of the 

numeric target level for each pesticide under acute and chronic exposure conditions. For 

example, the numeric target for diazinon under short term, acute conditions is 80 ng/L. The 

wasteload and load allocations are set at 72 ng/L, after subtraction of 8 ng/L to provide the 10% 

margin of safety. 

Allocations for Freshwater Water Bodies 

Table 3-2 presents the concentration-based freshwater allocations for chlorpyrifos and 

diazinon; these apply to all point sources (wasteload allocations) and to all non-point sources 

(load allocations). The diazinon allocations apply to freshwater discharges into San Diego Creek 

Reach 1 and Reach 2. The chlorpyrifos allocations apply to freshwater discharges into San 

Diego Creek (Reach 1 and Reach 2) and freshwater discharges into Upper Newport Bay 

including Santa Ana Delhi Channel, Big Canyon Channel and other drainages to Upper Bay. 

This includes discharges from agricultural and residential lands, including flows from the storm 

water systems. These limits apply regardless of season and flow; i.e., at all times of the year. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 27 

Table 3-2: Diazinon and Chlorpyrifos Allocations for San Diego Creek 

Category Diazinon (ng/L) Chlorpyrifos (ng/L) 

 Acute Chronic Acute Chronic 

Wasteload 

Allocation 

72 45 18 12.6 

Load 

allocation 

72 45 18 12.6 

MOS 8 5 2 1.4

TMDL 80 50 20 14 

Allocations for Upper Newport Bay

Table 3-3 presents the saltwater allocations for chlorpyrifos; these apply to all point 

sources (wasteload allocations) and to all non-point sources (load allocations). It applies to 

saltwater allocations in Upper Newport Bay, defined from San Diego Creek at Jamboree Rd. 

down to Pacific Coast Highway Bridge. These limits apply regardless of season and flow; i.e., at 

all times of the year. 

Table 3-3. Chlorpyrifos Allocations for Upper Newport Bay 

Category Acute (ng/L) Chronic 

(ng/L) 

Wasteload 

allocation 

9.9 5.04 

Load allocation 9.9 5.04 

MOS 1.1 0.56

TMDL 11 5.6 

Chronic means 4-consecutive day average 

Needed Reductions 

Table 3-4 summarizes the estimated needed concentration based (load) reductions for 

diazinon and chlorpyrifos in order to achieve the TMDL numeric targets in San Diego Creek. 

The difference between the current load and the allocation is the needed reduction. Chlorpyrifos 

concentrations may have begun to decline in 2000 and 2001, based on indications of a reduction 

in usage from the DPR database as well as from the Sales and Use Survey (Wilen 2001) 

conducted in late 2000. To date, there are no clear indications of declining trends in diazinon 

usage in the watershed. This table indicates the estimated needed reduction during average 

storm flows. As discussed above, the majority of the pesticide load derives from stormflow. 

Table 3-4. Needed Load (concentration based) Reductions for San Diego Creek. 

Constituent San Diego Creek 

(1996-2001) 

Allocation Needed Reduction 

 Storm Average Max Chronic Acute Chronic Acute 

 (ng/L) (ng/L) (ng/L) (ng/L) (ng/L) (ng/L) 

Chlorpyrifos 120 580 12.6 18 90% 97% 

Diazinon 848 960 45 72 95% 93% 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Phase out agreements 

Diazinon—In January 2001, EPA released a revised risk assessment and an agreement 

with registrants to phase out most diazinon uses (EPA 2001b). Under the agreement, all indoor 

uses will be terminated, and all outdoor non-agricultural uses will be phased out over the next 

few years. Retail sales will be banned after December 31, 2002. The EPA expects, on a national 

basis, that these actions will end over 90% of current uses. Within the Newport Bay watershed, 

about one-third of the agricultural crop uses will be removed. 

Chlorpyrifos--In June 2000, EPA published its revised risk assessment and agreement 

with registrants for chlorpyrifos (EPA 2000b). The agreement imposes new restrictions on 

chlorpyrifos use in agriculture, cancels or phases out nearly all-indoor and outdoor residential 

uses, and also cancels non-residential uses where children may be exposed. Application rates for 

non-residential areas where children will not be exposed (golf courses, road medians, industrial 

plant sites) will be reduced. Public health use for fire ant eradication and mosquito control will 

be restricted to professionals. Non-structural wood treatments will continue at current rates. 

Since the EPA estimates, on a nation-wide basis, that about 50% of the chlorpyrifos use (both 

licensed and unreported) takes place at residential sites, the agreement is likely to result in more 

than 50% decrease in chlorpyrifos use. 

While these agreements should result in significant decreases in OP pesticide use and the 

resulting discharge concentrations to the waterbodies, additional measures appear to be necessary 

to achieve the reductions set forth above. 

Seasonal variation/Critical conditions 

Pesticide usage correlates roughly with the season, with increasing usage in the warmer 

months due to increased pest activity. However, runoff into the drainage channels is greatest 

during the wet season, and higher pesticide concentrations are observed during storm events. 

The higher pesticide concentrations primarily account for the toxicity observed in stormwater 

samples collected in the watershed. The chronic criteria used as the basis for the numeric targets 

are designed to ensure protection of aquatic life during all stages of life, including the most 

sensitive stages. Because the TMDL is being expressed as a concentration, a detailed analysis of 

critical conditions is unnecessary. The concentration-based allocations (Table 3-2 and 3-3) will 

apply and be protective during all flow conditions and seasons. 

Margin of Safety 

An explicit 10% margin of safety was applied to the recommended criteria derived by the 

CDFG (2000a) and EPA (1986) for diazinon and chlorpyrifos. This explicit margin of safety is 

intended to account for uncertainties in TMDL calculation methods and concerning pesticide 

effects (e.g., potential additive and synergistic impacts from exposure to multiple OP pesticides) 

that may aggravate water quality impacts due to diazinon and chlorpyrifos usage in the 

watershed. 

In addition to the explicit margin of safety, conservative assumptions were used in 

applying the numeric targets within the watershed. These conservative assumptions serve as 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 29 

implicit margins of safety to provide additional protection for aquatic life and minimize aquatic 

toxicity. 

1. No adjustment was made to reflect the possibility of pesticide breakdown from point of 

discharge to San Diego Creek. Scientists have measured that half-lives of diazinon and 

chlorpyrifos in water range from a few days up to six months, therefore some degradation is 

likely to be occurring after application and within flowing waters. Assuming discharges are 

within the specified concentration-based allocations, and that such degradation (via biotic 

and abiotic processes) occurs, there will be sufficient protection for aquatic life. 

2. No adjustment was made to reflect the possibility of mixing and dilution within the drainage 

channels. In particular, the dilution capacity provided by groundwater seepage has not been 

factored into the TMDLs. 

3. The selected numeric targets for chlorpyrifos and diazinon are the most stringent 

concentration-based values for both freshwater and saltwater bodies. For these TMDLs, EPA 

has selected the lowest recommended values from California Dept. of Fish & Game or (in the 

case of chlorpyrifos in saltwater) the EPA criterion as the best water quality indicators for 

diazinon and chlorpyrifos. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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IV. Selenium TMDLs 

TMDLs are required for selenium (Se) for San Diego Creek, Upper Bay, Lower Bay, and 

Rhine Channel. Much of the work presented below and in the Technical Support Document—

Part D for Selenium is based on the Se draft TMDLs written by Regional Board staff (2001b). 

Problem Statement 

Selenium is a naturally occurring element that persists in soils and aquatic sediments and 

readily bioaccumulates through the food chain at levels that can cause adverse effects on higher 

level aquatic life and wildlife including fish and birds that prey on fish and invertebrates. 

Selenium can become mobilized and concentrated by weathering and evaporation in the process 

of soil formation and alluvial fan deposition in arid and semiarid climates (Presser, 1994). 

Dissolved selenium concentrations in San Diego Creek at Campus, and in tributaries to 

San Diego Creek, consistently exceed the chronic (4-day average) CTR criterion for freshwaters 

(5 ug/L). This has been observed in numerous studies, which also cite occasional exceedances of 

the acute (1 hour max.) criterion (Hibbs and Lee 1999, IRWD 1999, Lee and Taylor 2001a). 

Dissolved selenium concentrations in Newport Bay do not exceed the CTR saltwater criterion 

(71 ug/L); nonetheless, fish tissue data indicate that selenium loadings may be causing toxicity or 

contributing to conditions threatening wildlife in Upper and Lower Bay (see next paragraph). 

Freshwater and saltwater toxicity tests (designed for metals and trace elements such as Se) are 

currently in progress (SCCWRP 2001a; 2001b). 

In the majority of aquatic sediment samples analyzed from Newport Bay watershed, 

selenium concentrations are below levels of concern (2—4 mg/kg dry) as defined by Enberg et 

al. (1998). Mussel and fish tissue concentrations from all waterbodies are below the screening 

value (20mg/kg wet) for protection of human health as established by OEHHA (1999). 

However, these same tissue results are within the range of levels of concern (4—12 mg/kg dry) 

for toxicological and reproductive effects of wildlife (Enberg et al. 1998 and Henderson et al. 

1995). In San Diego Creek, tissue concentrations of selenium in small whole fish show an 

increasing trend from 1983 to 2000 (TSM, 2001)). Fish fillet results in Newport Bay do not 

appear to have the same trend and maximum levels barely approach 4 mg/kg dry (TSM 

database), which is below reported levels of concern. Studies of avian reproductive success, 

specifically including Se concentrations in eggs, have not been completed. 

Numeric Targets 

As discussed in Section II, the California Toxics Rule (CTR) includes numeric water 

quality standards (objectives) for selenium which are designed to protect aquatic life (USEPA 

2000a). As discussed below, EPA’s analysis of flows in San Diego Creek indicates that the 

duration of measured high flows exceeded 4 days in numerous instances during the evaluated 

period of record. Mean water residence time in the Bay also exceeds 4 days on average. 

Because the more stringent chronic standards are applied based on a 4 day averaging period, 

EPA has determined that it is appropriate to apply the chronic selenium standards at all flow 

levels in San Diego Creek and in Newport Bay. Therefore, the numeric targets proposed for the 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 31 

Newport Bay watershed selenium TMDLs are the chronic freshwater and saltwater objectives 

included in the CTR. 

The U.S. Fish and Wildlife Service concluded that the current CTR freshwater 

chronic water quality criterion for fresh waters (5 μg/L) may not be fully protective of 

threatened and endangered fish and wildlife species. In response to EPA’s request for a 

formal consultation on the CTR pursuant to the Endangered Species Act, USFWS 

prepared a biological opinion document on the effects of the promulgation of the CTR on 

the listed species and critical habitats in California (USFWS 2000). USFWS found that 

the chronic selenium criterion for fresh waters may not protect threatened and endangered 

fish and wildlife dependent on the aquatic ecosystem for development and/or foraging. 

USFWS opinion was based on extensive review of experimental and field data conducted 

over the past decade. USFWS concluded that a chronic criterion for selenium of ≤2 μg/L 

would be appropriate based on its review of available research. In response to this 

opinion, USEPA has agreed to reevaluate the criteria for selenium and to propose revised 

aquatic life criteria for selenium in California by January of 2003.

 EPA is currently engaged in a process of revising its national criteria 

recommendations for selenium based, in part, on the USFWS opinion concerning the 

CTR. However, the numeric objectives for selenium water column concentrations have 

not yet been changed. The Regional Board proposed numeric targets for its draft 

selenium TMDLs which are based on the USFWS recommended chronic criterion of 2 

μg/L. The Regional Board draft TMDLs also apply a higher numeric target of 10 μg/L 

under high flow conditions based on its judgment of the level of protection needed under 

higher flows. 

 EPA is basing the proposed Se TMDLs on the currently applicable chronic 

numeric standard of 5μg/L under all flows because the process of reviewing and revising 

the water column objectives has not been completed. 

EPA is also inviting comment on two alternative approaches to setting the 

TMDLs. The first method is based on the more stringent target level of 2 μg/L 

recommended by USFWS. This target value would be applied to all flow tiers. Adoption 

of TMDLs based on this more stringent numeric target would result in TMDLs and 

allocations that are 40% of the TMDLs and allocations based on the currently applicable 

chronic standard of 5 μg/L. This alternative would result in more stringent TMDLs than 

the proposed approach but is not based on an adopted numeric water column objective 

that replaces the existing water column objective.

We are also inviting comment on the State’s proposed variant on this alternative. 

The draft State TMDLs apply the 2 μg/L target at baseflow and small flow tiers, and a 10 

μg/L target at the medium and high flow tiers. This alternative would allow higher Se 

concentrations under high flows based on the State’s conclusion that high flow conditions 

are temporary and that numeric targets based on acute Se effects are more appropriate for 

these higher flow conditions. Adoption of this alternative approach would result in 

TMDLs that are 160% of the TMDLs and allocations based on the currently applicable 

standard of 5 μg/L. This alternative is less stringent overall than the proposed approach 

although it is based on a more stringent standards interpretation under low flows and a 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 32 

less stringent standards interpretation under high flows. The rationale for setting basing 

TMDLs and allocations for higher flow situations on the less stringent acute numbers 

may not be fully supported by local flow histories.

Freshwater targets 

EPA is applying the same numeric targets based on the 5 μg/L chronic water quality 

standard under all freshwater flow conditions in San Diego Creek. EPA has decided to apply 

only the chronic standards because these standards appear to be applicable under all the flow 

conditions observed in the San Diego Creek watershed. The applicable chronic water quality 

standards are based on the presumption that pollutant exposures of 4 days or longer in duration 

will not occur more than once in any three year period. Based on EPA’s analysis of daily flow 

records for 1995, 1997, 1998, 1999 and 2000, EPA divided all observed flows into 4 flow 

categories or tiers: baseflow (<20 cubic feet/second (cfs)), small flows (between 20 and 42 cfs), 

medium flow (between 42 and 190 cfs), and large flow (>190 cfs). EPA has concluded that a 

significant percentage of flows in all flow categories, and in the medium flow and large flow 

categories in particular, exceeded 4 days in duration during this period. Therefore, it was 

appropriate to apply the more protective chronic standard under all flows. The Technical 

Support Document—Part B provides a complete explanation of these flow tiers and the 

associated mean annual flow volumes for calculating loads. 

Saltwater target 

The numeric target for dissolved Se in saltwater is 71 ug/L from CTR (USEPA 2000a). 

The USFWS concurred with this saltwater value in its review of the CTR. Therefore, this target 

is expected to result in protection of all designated uses in Newport Bay. 

Table 4-1. Numeric targets for Selenium in San Diego Creek and Newport Bay (ug/L). 

Waterbody/type Total Se* 

Acute Chronic 

Dissolved Se# 

San Diego Creek/freshwater 5 5 N/a 

Newport Bay & Rhine 

Channel/saltwater 

N/a N/a 71 

*Total recoverable = unfiltered sample 

#dissolved = <0.45 um filter 

Source Analysis 

Several monitoring studies, completed with a specific focus on Se during short time 

periods, provide most of our current understanding of Se sources (IRWD 1999; Hibbs and Lee 

2000; Lee and Taylor 2001a). The synopsis is presented below; the Technical Support 

Document—Part D presents a more thorough source analysis and description of these studies. 

An investigation of selenium sources shows that shallow groundwater is a significant and 

constant source of selenium to surface waters in the San Diego Creek watershed (Hibbs and Lee 

1999). Groundwater may seep into surface waters via natural processes or it may be pumped as 

part of groundwater cleanup or dewatering operations which discharge into surface waters. Thus 

selenium contributions to the watershed include both non-point sources (seepage) and point 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 33 

sources (cleanup and dewatering). Surface channels immediately downstream of nurseries were 

found to have low Se concentrations in base flow conditions (Hibbs and Lee 1999; Lee and 

Taylor 2001a). 

San Diego Creek contributes the largest load of selenium among all tributaries to 

Newport Bay (Lee and Taylor 2001a). Of the load from San Diego Creek, Peters Canyon Wash, 

which conveys selenium from selenium-laden shallow groundwater, represents the major source 

in dry weather. These sources may include runoff from hillsides, open spaces, agricultural lands, 

and commercial nursery sites. High concentrations were found in nursery channels during rain 

events, although it remains unclear if the Se sources are from commercial nurseries or from 

sources existing upstream of the nurseries. During rain events, the Se load from upper reach of 

San Diego Creek was comparable to that from Peters Canyon Wash; suggesting runoff from 

open space is a significant source during rain events. Low concentrations were found in nursery 

channels during baseflow conditions. 

Table 4.2 Reported Selenium conc. in San Diego Creek and Santa Ana-Delhi Channel (ug/L) 

Location 

Lee 

andTaylor*

5/31/00 

Hibbs and Lee¥

10/31/99 

IRWD@

12/97–3/99 

San Diego Creek 

(at Campus Dr.) 

22.1 19 42.5 

Santa Ana-Delhi 

(at Irvine Ave.) 

11.9 --- --- 

*Lee and Taylor (2001a) results for unfiltered samples 

¥

Hibbs and Lee (1999) results for dissolved sample 

@ IRWD (1999) result is arithmetic average of time period indicated, dissolved 

sample 

Urban runoff is found to contain very low Se concentrations (< 1.5 μg/L) (Lee and Taylor 

2001a). Atmospheric deposition of selenium is not significant compared to loading from San 

Diego Creek and other freshwater tributaries (Mosher and Duce, 1989). The concentration of 

selenium in ambient seawater (0.080 ug/L) is unlikely to cause ecological impacts (Nriagu, 

1989), and seawater is not believed to comprise a significant source of selenium loading to 

Newport Bay. 

Figure 4-1 summarizes the sources of selenium in the watershed. The significance of 

these sources varies both on discharge location and season of the year. Nursery runoff shows 

moderate concentrations (~10 μg/L) in dry weather and are potential sources during storms (Lee 

and Taylor 2001a). Runoff from open space, hillsides, and agricultural lands could also be 

significant sources during rain events. In general, groundwater seepage/infiltration represents a 

significant and constant source. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 34 

Nurseries Groundwater

Cleanup

Groundwater

Dewatering

Groundwater Agricultural

Runoff

Open Space &

Hillside Runoff

San Diego Creek & other tributaries Newport Bay

Urban

Runoff

Atmospheric

Deposition

Figure 4.1 Sources of selenium in the Newport Bay/San Diego Creek watershed. 

(For EPA TMDLs, nurseries have been grouped with agricultural runoff in Table 4-5 and 

allocations tables.) 

Loading Capacity/Linkage Analysis 

The loading capacities and associated TMDLs and allocations for selenium are expressed 

as mass loads per time. Different approaches were used to calculate loading capacities for the 

freshwater and saltwater water bodies in the watershed. 

San Diego Creek 

This TMDL uses a flow-based approach to determine the loading capacity for Se in San 

Diego Creek. This approach addresses contributions of Se under various flow regimes or tiers. 

Four flow tiers were chosen based on a statistical analysis of daily flow records for San Diego at 

Campus Dr. (See Technical Support Document—Part B for more explicit information about 

freshwater flows.) Specific loading capacities for each flow tier are calculated from the desired 

Se concentration (i.e., the numeric target) and the annual mean flow volume associated with each 

tier (Table 4-3). The sum of loads in these four tiers constitutes the total loading capacity for 

San Diego Creek per year. 

Table 4-3 Flow based tiers and corresponding volumes in San Diego Creek 

Flow tier Corresponding 

flow 

(cfs) 

Flow Volume* 

associated with tier 

(thousand cubic ft.) 

Se 

conc. 

with 

tier 

(ug/L) 

Loading capacity 

per tier@

(lbs/yr.) 

Base flow 0—20 305 5 95 

Small flows 20—42 107 5 33 

Medium flows 42—190 126 5 39 

Large flows >190 1208 5 377 

Total annual 

amount 

 1746 545 

*Annual mean volume based on OCPFRD records for water years: 1995, 1997, 1998, 1999, 2000. 

@Se per tier (lbs/yr) = flow volume (ft3

/yr) x desired Se target (ug/L) x conv. factor (0.00006243 lbs x L/mg 

x ft3

)
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 35 

Newport Bay 

The loading capacity for Newport Bay is presented in Table 4-4. This loading capacity is 

calculated using the Se saltwater numeric target (71 ug/L) and the volume of water in Newport 

Bay. (Mean volume is 19 million cubic meters based on low and high tide estimates (RMA, 

1999)). 

Table 4-4 Loading capacity of San Diego Creek and all Newport Bay waterbodies 

Waterbody Loading capacity 

(lbs/yr.) 

San Diego Creek and tributaries 545 

Santa Ana Delhi 110¥

 

Upper and Lower Bay and Rhine 

Channel 

232,000*

¥

Se value determined via similar method to those used for San Diego Creek but flow records for Santa Ana Delhi 

Channel for water years: 1995, 1997, 1998, 1999, 2000 

*based on calculation CTR saltwater chronic value (71 ug/L) and the volume of Newport Bay water, adjusted to 

account for daily water movement into and out of the Bay from the Pacific Ocean. 

TMDL and Allocations 

EPA is setting the TMDL equal to the loading capacity for each waterbody presented 

above (Table 4-4). For this TMDL, EPA has defined wasteload allocations (WLAs) for point 

sources and load allocations (LA s) for non-point sources. Table 4-5 lists the source categories 

for which allocations are proposed. 

TMDL = Σ (wasteload allocations) + Σ (load allocations) + Margin of Safety 

Table 4.5 Sub-categories of allocations for Se in San Diego Creek. 

Wasteload allocations Load allocations 

Groundwater cleanup 

Groundwater dewatering 

Urban runoff 

Groundwater (background) 

Nurseries & Agricultural runoff 

Open space and hillside runoff 

Atmospheric deposition 

Wasteload and load allocations are assigned based on the following general guidelines: 

• Allocations among source categories are assigned in proportion to the relative 

significance of the sources, and indicated by available data concerning reported 

monitoring concentrations, discharge flow rates, and Se loading (see Source Analysis 

section), and/or acreage of land uses. In general, significant sources require larger 

reductions in loading than minor sources to attain the numeric target. 

• Within the same source category, allocations for individual dischargers are prorated 

based on land area. 

• For each flow tier, allocations are assigned based on the nature of each source. For 

example, runoff from hillside, open space, and agricultural lands is minimal in dry season 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 36 

but loads dramatically increase during high stream flows associated with wet weather. 

Loading from shallow groundwater is likely to change because creeks may change from 

gaining streams (water input from groundwater during dry weather) to losing streams 

(surface runoff percolates into shallow groundwater areas) as a result of high water level 

in the creeks during and/or immediately after rain events. 

• Atmospheric deposition is removed from the allocation scheme due to low loading from 

this source (see TSD pg. D-12). Any loading from atmospheric deposition is less than 

the explicit margin of safety discussed below. 

Discharges from groundwater cleanup and groundwater dewatering could be significant 

sources and loading from those operations depends on their location. However, the 

quantification of loading from individual discharges is not feasible at this time due to lack of Se 

data in effluent from those operations. In this TMDL, allocations are assigned to groundwater 

cleanup and dewatering as one point source group each. EPA recommends that the Regional 

Board monitor flow and Se concentrations in discharges from cleanup and ground water 

dewatering operations as part of an implementation strategy for this TMDL. Loading limits for 

individual discharges can then be assigned based on the monitoring data. 

Table 4-5 shows the wasteload and load allocations based on the sum of loading capacity for 

San Diego Creek and Santa Ana-Delhi Channel. The estimated current annual load is considered 

as the current load of selenium at Campus Drive based on IRWD monitoring data (4/98-3/99). 

The Se TMDLs and allocations are expressed in mass-based annual loads. Daily loads could be 

calculated by dividing the annual TMDLs and allocations by 365. However, annual loadingbased TMDLs and allocations are more appropriate because prospective adverse effects 

associated with Se are associated more with long term mass loadings and bioaccumulation 

effects than with short term or acute effects. An explicit margin of safety (MOS) of 10% was 

included to account for uncertainty in the analysis and ensure compliance with water quality 

objectives. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Table 4-5 Wasteload and Load allocations of Selenium for Newport Bay watershed. 

Source Loading capacity 

(lbs/year) 

Current 

load 

Estimated 

reductions 

 Tier 1 Tier 2 Tier 3 Tier 4 Annual 

total 

 

WLA 

MCAS Tustin 2.06 0.72 0.75 6.12 9.64 

Silverado 

GW 

4.12 1.44 1.70 16.31 23.6 

GW clean up 8.23 2.89 3.2 28.55 42.9 

GW 

dewatering 

5.15 1.81 1.92 16.31 25.2 

Other GW 

facilities 

0.51 0.18 0.21 2.04 2.9 

Stormwater 

Permit 

0.51 0.36 0.43 4.08 5.4 

WLA subtotal 20.58 7.40 8.20 74.41 109.64 

 

LA 

All nurseries 4.1 1.4 1.7 16.3 23.6 

Ag runoff 7.2 2.7 3.4 34.7 48.0 

Undefined 

sources #

71.0 24.6 29.3 283.5 408.3 

LA subtotal 82.3 28.7 34.4 334.4 479.9 

MOS 65.5 

Total 102.9 36.1 42.6 407.9 655.04* 3248¥ 82% 

* sum of loading capacity for San Diego Creek and Santa Ana-Delhi Channel, 

 (based on 5 ug/L applied to all flow tiers) 

# undefined sources includes: open space and hillside runoff, shallow GW and saltwater Se 

¥current load based on IRWD Se data (1998-99) and corresponding OCPFRD flow records 

Seasonal variation/Critical conditions 

As previously described, EPA is calculating these Se TMDLs based on freshwater flow 

rates instead of seasons. The flow rates correspond to flow tiers which address the continuous 

range of San Diego Creek flow rates throughout the year. In this flow-based approach, 

allocations are based on in-stream flow rates which are influenced by precipitation and runoff. 

Given that storm events may occur at any time of the year, the corresponding elevated stream 

flows are addressed by this flow-based approach. 

Margin of Safety 

In this TMDL, an explicit margin of safety is used to account for other technical 

uncertainties. The margin of safety is set at 10% of the annual loading capacity (ca. 65 lbs/year). 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Most of the uncertainty associated with calculation of the TMDL for selenium relates to 

freshwater flow rates. The average flow rates for dry and wet seasons were calculated using five 

years of OCPFRD flow data (water year 1995, 1997, 1998,1999, 2000, since 1996 flow data is 

not available). As discussed in the Technical Support Document—Part B, the precipitation 

records (and therefore flow records) for these five years are elevated relative to other five-year 

groups. This is attributed to 1998 when San Diego Creek has record stream flows due to El Nino 

weather conditions. Using these slightly higher than average stream flows, this yields a loading 

capacity that is slightly elevated relative to drier water years
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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V. Metals TMDLs 

TMDLs are required for dissolved copper, lead and zinc in San Diego Creek, Upper Bay, 

Lower Bay and Rhine Channel. TMDLs are required for cadmium in San Diego Creek and 

Upper Bay only. Information related to these metal TMDLs can be found in two Technical 

Support Documents—Part B which describes freshwater flows and Part E which describes 

metals source analysis and methods used to determine loading capacity and existing loads. 

Problem Statement 

Cadmium, Copper, Lead and Zinc—Dissolved heavy metal concentrations in San Diego 

Creek and other freshwater tributaries exceeded CTR standards during wet weather only. More 

specifically, cadmium, copper and lead results exceeded chronic CTR values; copper and zinc 

data exceeded acute CTR values (OCPFRD 2000). Water column concentrations measured in 

Newport Bay are highly variable. In general OCPFRD results exceed water quality standards 

and these data are much higher than data reported by IRWD (1999) which rarely exceed 

saltwater CTR values. While direct comparison of these results is not feasible, EPA has 

identified some quality control problems with metals analyses in saltwater by OCPFRD’s 

contract lab and has concluded that they may not be reliable for TMDL development. 

Sediment metal concentrations generally increase along the gradient from freshwater to 

saltwater with maximum levels found in Rhine Channel. Sediment toxicity has been repeatedly 

observed in sediment and porewaters of Upper and Lower Bay, including Rhine Channel 

(BPTCP 1997; Bay et al. 2000, SCCWRP 2001a). Porewater is water found within the bottom 

sediments. Evidence of degraded benthic organisms also exists in these saltwater bodies. The 

cause of toxicity and benthic degradation is unknown, however a statistical correlation was found 

between sediment and porewater toxicity to amphipods and sea urchin larvae and elevated 

copper, lead and zinc sediment concentrations (BPTCP 1997). Toxicity identification evaluation 

(TIE) studies of saltwater bodies are currently in progress (SCCWRP 2001a). 

Bioconcentration of copper and zinc has been observed in mussels within Lower Bay and 

Rhine Channel (SMW 2000). However, fish tissue concentrations of these metals are not 

elevated relative to respective metal screening values defined by OEHHA (1999). Cadmium, 

Copper, Lead and Zinc may bioconcentrate in lower organisms but these metals generally do not 

bioaccumulate and therefore are not likely to threaten organisms higher in the food chain such as 

fish-eating birds. 

Numeric targets 

In freshwater systems, the dissolved cadmium, copper, lead and zinc water quality 

criteria are hardness dependent as defined in CTR (USEPA 2000a). Like many flowing 

freshwater bodies, San Diego Creek waters exhibit a wide range of flow rates and hardness 

levels. That is, low flow rates have high hardness values (e.g., 20 cfs corresponds to >400 mg/L 

hardness) whereas high flow rates have lower hardness (e.g., 760 cfs corresponds to 240 mg/L 

hardness). This inverse relationship between flow rate and hardness influences both acute and 

chronic metals numeric targets. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 40 

Based on conclusions drawn from analyzing flow records measured at San Diego Creek 

at Campus (OCPFRD), EPA proposes four flow tiers for San Diego Creek. A hardness value is 

defined for each flow tier which is used to calculate the associated acute and chronic targets for 

dissolved metal. (Table 5-2). For the baseflow and small flow tiers, EPA used the maximum 

hardness value (400 mg/L) as allowed in CTR (USEPA 2000). A review of available data 

indicated that actual hardness associated with flows in these tiers often exceeds 400 mg/L; 

however, the CTR caps the allowable hardness value that can be used to calculate the resulting 

hardness. For the medium flows EPA selected the highest flow value within this tier to 

determine the corresponding hardness value. For large flows, EPA reviewed daily flow rates for 

4-consecutive days and used the highest (4 day) mean flow rate to determine the corresponding 

hardness value. 

EPA is identifying numeric targets for both chronic and acute conditions; however, the 

TMDLs are calculated based only on the chronic standards and associated numeric targets. EPA 

is identifying the acute numeric targets solely to assist in interpreting future monitoring results 

for assessing instantaneous compliance with standards. EPA considered applying acute targets 

to calculate TMDLs for the medium and large flow tiers. However, EPA decided to apply only 

the chronic targets because our review of daily flow records indicates that storm events produce 

sufficiently elevated flows (>190) that linger for 4-consecutive days or longer. Similarly, it was 

appropriate to calculate TMDLs for Newport Bay based on chronic targets because average 

water residence time in the Bay was estimated to exceed 4 days under all likely flow conditions. 

The investigation of precipitation, flow rates and the relationship to hardness is explained more 

thoroughly in the Technical Support Document—Part B. 

Table 5-1. Flow based tiers and corresponding hardness values in San Diego Creek. 

Flow tier Corresponding 

flow rate 

(cfs) 

Volume associated 

with tier # 

(thousand cubic ft.) 

Flow rate used to 

determine hardness 

Corresponding 

Hardness 

(mg/L) 

Base flow 0--20 305 N/a* 400 

Small flows 20-42 107 N/a* 400 

Medium 

flows 

42-190 126 190 320 

Large flow >190 1208 1861 190 

# mean volume for each tier based on OCPFRD daily flow records for water years: 1995,97,98,99,00

* flow rate not used for these tiers; hardness determined by CTR (max = 400 mg/L)

Freshwater bodies 

For freshwater bodies in San Diego Creek, EPA calculated the hardness-based dissolved 

metals numeric targets (Table 5-2) using equations provided in CTR. EPA is identifying targets 

representing concentrations of the metals in the water column for each flow tier. As discussed 

above, we are identifying targets for chronic conditions (which are used in the calculation of 

these TMDLs) and for acute conditions (which are included solely to assist in interpreting future 

monitoring results. The Technical Support Document—Part E presents a step-by-step discussion 

of how numeric targets were calculated based on CTR equations for each pollutant, fresh water 

flow rates, and corresponding hardness values. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Table 5-2. Metals Numeric Targets (ug/L) based on flow tiers for San Diego Creek. 

Base and Small Flows 

(<42 cfs) 

hardness @ 400 mg/L 

Medium Flows 

(42 - 190 cfs) 

hardness @ 320 mg/L 

Large Flows 

(>190 cfs) 

hardness @ 190 mg/L 

Dissolved Metal Acute Chronic Acute Chronic Acute Chronic 

Cd 19.1 6.2 15.0 5.3 8.6 3.6 

Cu 50 29.3 40.2 24.2 30.7 15.5 

Pb 281 10.9 223 8.7 165 5.0 

Zn 379 382 314 316 246 203.5 

Saltwater bodies 

In saltwater systems, the dissolved metals numeric targets are straightforward; i.e., 

hardness is not involved. Additional numeric targets have also been selected to address toxicity 

in saltwater sediments. These sediment targets are the lowest (most protective) levels available 

in scientific literature and are derived from Florida Department of Environmental Protection 

studies (Macdonald et al, 1996). The dissolved water column and sediment targets apply for Cu, 

Pb and Zn within Upper Bay, Lower Bay and Rhine Channel, and for Cd only in Upper Bay. 

Table 5-3. Numeric targets for metals in Newport Bay 

Metal

Dissolved 

saltwater 

acute target 

(ug/L) 

Dissolved 

saltwater 

chronic target 

(ug/L) 

Alternate target in 

 saltwater 

sediments 

(mg/kg dry) 

Cd* 42 9.3 0.67 

Cu 4.8 3.1 18.7 

Pb 210 8.1 30.2 

Zn 90 81 124 

(Source: CTR values for dissolved metals in saltwaters; Florida DEP values for sediments) 

*Cd value applies for Upper Newport Bay only 

EPA also considered setting targets for both fresh water and salt water in terms of total 

metals instead of dissolved metals due to the potential concern that particulate metals could 

become bioavailable. There are several reasons for selecting dissolved metal targets: 

a) The existing numeric standards are expressed in the CTR in terms of dissolved metals (EPA 

2000a). The CTR rationale is that dissolved forms are the most bioavailable to aquatic 

organisms. 

b) Particulate/dissolved metal ratios were estimated from OCPFRD stormwater data and could 

be used to translate these dissolved metal mass loads into total loads. However, these 

translator values developed from paired metals data are close to unity. For example, we 

calculated a site-specific translator ratio for copper of 1.16 total Cu to dissolved Cu; this is 

reasonably close to the generic EPA value that dissolved is roughly 80% of total 

concentration. Therefore, dissolved metals measures are probably fairly good predictors of 

total metals concentrations. Moreover, we have incorporated an extra explicit margin of 

safety to account for the possibility that a focus on dissolved metals does not fully account 

for total metals concentrations. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 42 

c) EPA recognizes the Sediment TMDLs already established for these waterbodies will 

augment efforts to reduce total metal loadings into the saltwater bodies and help to achieve 

the sediment targets to protect benthic organisms by reducing discharges of metalcontaminated sediments. 

Source Analysis 

This section summarizes our analysis of the major sources of dissolved cadmium (Cd) for 

San Diego Creek and Upper Newport Bay and for dissolved copper (Cu), dissolved lead (Pb) and 

dissolved zinc (Zn) within all water bodies of Newport Bay. This synopsis draws conclusions 

from several different studies which report concentrations of metals in the water column and 

sediments of all water bodies. Where applicable this synopsis also presents information about 

inputs of copper from sediments and from recreational boats moored in Newport Bay. The 

Technical Support Document—Part E presents a more thorough presentation of all monitoring 

results and source analysis pertaining to metals. 

Within San Diego Creek and its tributaries, metal inputs are heavily influenced by rainfall 

and stream flow rates. Base flow conditions yield approximately 25% of total loadings; storm 

events yield approximately 55% of total loadings; the remainder is associated with low and 

medium flows. Surface runoff is estimated to be the largest source of metals; this includes both 

natural and man-made contributions. A recent study of pollutant inputs from tributaries within 

the San Diego Creek watershed concluded that the largest metals inputs come from “urban 

stations”, whereas agricultural and open space exhibit the lowest loadings (Lee and Taylor 

2001a). The difference could be as much as five fold higher for urban areas based on estimates 

of total copper per acre of runoff (see Table E-7 in TSD—Part E). While this study does provide 

a basis for estimating the relative importance of metals loadings from different land uses within 

the watershed, it is infeasible to accurately estimate annual loads since loading data are 

extremely limited. 

Currently, the only published annual metal loading estimates from freshwater tributaries 

are based on total (unfiltered) metal concentrations (OCPFRD 2000). These estimates for Cu, Pb 

and Zn indicate that San Diego Creek contributes up to ten times more of each metal than Santa 

Ana-Delhi Channel. Within San Diego Creek, inputs from Peters Canyon Wash and the rest of 

the San Diego Creek drainage are about the same. Table 5-4 summarizes these estimates for San 

Diego Creek and Santa Ana-Delhi Channel for the 1998 and 1999 water years. (The 1998 water 

year is defined as from July 1997 to June 1998.) These results show considerable variability due 

to different rainfall amounts and fluctuating freshwater flows during each water year. The 1998 

water year is considered an extremely wet year (38.4 inches of rainfall) due to El Nino 

conditions; whereas, 1999 water year is considered slightly dry (8.8 inches) relative to average 

annual rainfall (13.3 inches). 

Another study of surface water runoff during storm events has approximated the relative 

contribution of metals associated with natural sources such as soil minerals versus the metal 

inputs from anthropogenic activities. The authors used results from unfiltered (i.e., total metal) 

samples in the Santa Ana River watershed and report the anthropogenic contribution is metal 

specific: Cd (63% human-caused), Cu(42%), Pb (35%) and Zn (33%) (Schiff and Tiefenthaler 

2000). Total metals loading estimates in Table 5-4 have also been adjusted based on these 

results to report the approximate load believed to be associated with anthropogenic activities. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Table 5-4 Estimates of Total metal loadings from two freshwater inputs to Upper Bay 

Metal Site 1998 water 

year 

(OCPFRD) 

Adjusted 

1998 results 

(Man-made) 

1999 water 

year 

(OCPFRD) 

Adjusted* 

1999 results 

(Man-made) 

 Total load 

(lbs.) 

Total load 

(lbs.) 

Total load 

(lbs.) 

Total load 

(lbs.) 

Cu San Diego Creek 15,087 6261 1643 682 

 Santa Ana –Delhi 1643 682 185 77 

Pb San Diego Creek 10,385 3977 449 172 

 Santa Ana –Delhi 1297 497 124 47 

Zn San Diego Creek 63,021 20,985 3784 1260 

 Santa Ana –Delhi 7031 2341 805 286 

Source: 1998 and 1999 water year results from OCPFRD 2000 

*Adjustments made from man-made approximations reported by Schiff and Tiefenthaler 2000 

Several other sources of metals exist in the watershed: natural runoff from open spaces, 

nursery and agricultural applications, groundwater dewatering and cleanup, and atmospheric 

deposition. Monitoring data exist for natural dissolved metals concentrations in surface runoff 

from hillsides and open spaces. EPA has selected wet weather results from the San Joaquin 

Channel site (Lee and Taylor 2001a) to serve as proxy for these natural sources because the area 

upstream from this site is essentially undeveloped. Based on State pesticide use reports (CDPR 

1999) for some nurseries, applications of copper sulfate appears as the most prominent metal 

containing substance; nonetheless annual metal applications are small (e.g., 72 lbs/yr) relative to 

watershed wide surface runoff estimates (ranging from 1643 to 15,087 lbs/yr, Table 5-4). To 

date, reliable dissolved metal concentrations in shallow ground waters have not been reported. 

Atmospheric deposition—onto the watershed land surface and into San Diego Creek and other 

freshwater tributaries—has already been included within surface runoff estimates. It is 

considered minimal in comparison to other contributions to surface runoff because there are no 

likely local airborne sources of these metals. 

For the salt waters of Upper and Lower Newport Bay, including the Rhine Channel, the 

largest ongoing sources of most dissolved metals (except for Copper) are estimated to be the 

freshwater-borne loads from San Diego Creek (95% of freshwater-related loads), Santa AnaDelhi Channel (<5%) and other drainages (<1%). Ambient surface seawater may be the next 

most significant source. Concentrations of dissolved metals in seawater collected off the 

Southern California coast range from 0.06 ug/L for Pb, 0.1 ug/L for Cd, 0.2 ug/L for Cu, to 2.4 

ug/L for Zn (pers. commun., R. Gossett). The influence of ambient seawater on metal levels 

within Newport Bay depends on marine tides and freshwater flows from the watershed. During 

high tides and low freshwater flows, surface seawater contributions could be relatively higher, 

yet low tides concurrent with dramatically higher freshwater inputs during storm events would 

yield much lower ambient seawater contributions. 

The phenomenon of dissolved copper inputs to marine waters from recreational boats has 

been repeatedly monitored in San Diego Bay as reported in the draft TMDL for dissolved Cu for 

Shelter Island yacht harbor (San Diego RWQCB 2001). Using mass loading calculations 

presented in that TMDL and local data concerning boats in Newport Bay, passive leaching from 

recreational boats and underwater hull cleaning are estimated to comprise the most significant 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 44 

sources (>80%) for dissolved Cu into Lower Bay, Rhine Channel and, to some extent, Upper 

Bay. 

To date, no study within Upper Bay has examined whether sediment resuspension or 

porewater fluxes contribute significant metals loads to the water column. Porewater 

concentrations measured in Lower Bay (not including Rhine Channel) suggest that Cu levels are 

elevated enough to create potentially negative impacts (Bight ’98). Levels for the other metals 

are within the range of concentrations observed in ambient seawater and well below the 

dissolved saltwater numeric targets. 

Air deposition of metals is traditionally assessed in two parts—indirect and direct. 

Indirect deposition, where metals are deposited onto dry land areas and then washed into stream 

via surface runoff, has already been included as part of the freshwater inputs from San Diego 

Creek, Santa Ana Delhi Channel and other drainages to Newport Bay. Direct deposition, where 

metals directly enter the water surface, are less than 1% of metal contributions to Upper and 

Lower Bay. 

Loading Capacity/Linkage Analysis 

San Diego Creek and tributaries 

Metals loading capacities for San Diego Creek were calculated by multiplying the 

chronic numeric target calculated for each flow tier (see Table 5-1) by the mean annual water 

flow volume associated with each tier to yield an allowable mass load for each flow tier. This 

approach is similar to that presented in the Se TMDLs. (An example of this calculation for 

dissolved copper is provided in the Technical Support Document—Part F.) The sum of all four 

tiers equals the mass-based loading capacity for San Diego Creek (Table 5-5). 

Newport Bay 

For Upper and Lower Bay, including Rhine Channel, the loading capacities were also 

calculated by applying the chronic numeric target by the volume of water in the Bay, accounting 

for water exchange rates between Newport Bay and the Pacific Ocean. The loading capacities 

are based on the saltwater dissolved metals targets (Table 5-3); they are not hardness dependent. 

The mass-based loading capacity is shown in Table 5-5. (A description of this calculation is 

presented in Technical Support Document—Part F.) 

Concentration-based Option

 EPA is also considering expressing the loading capacities and associated TMDLs and 

allocations for San Diego Creek in terms of allowable chronic metals concentrations under 

different flows and associated hardness levels. Similarly, EPA is considering the alternative 

approach of expressing the loading capacities, TMDLs, and allocations for Newport Bay based 

on the allowable metals concentrations as expressed in the chronic numeric targets for the Bay. 

EPA is inviting comment on the concentration-based option, which is discussed further in the 

TMDL and allocations section below. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 45 

Table 5-5. Dissolved metal loading capacity for San Diego Creek and Newport Bay 

Dissolved 

Metal 

San Diego Creek 

Dissolved load 

(lbs/yr) 

Upper and Lower Bay 

including Rhine Channel 

Dissolved load (lbs/yr) 

Cd 488 12,367* 

Cu 2114 12,087 

Pb 726 26,889 

Zn 27,670 259,249 

*Cd load applies to Upper Bay only, where volume of Upper Bay is approximately 40% of the 

total volume of Newport Bay 

The mass-based and concentration-based approaches to expressing these TMDLs and 

allocations both have advantages and disadvantages, which are summarized below. 

On one hand, metals TMDLs need to protect against adverse effects on aquatic life 

associated with short term exposures to toxic metals. A concentration-based approach may be 

more sensitive to this kind of impact and less sensitive to problems associated with long term 

metals loading. Over longer time frames, cumulative metals discharges are of concern in 

embayments and possibly fresh water waterbodies because metals may associate with sediment 

and accumulate in bottom sediments, where they may contribute to sediment toxicity and 

associated ecosystem impacts. A mass-based approach may be more sensitive to this kind of 

impact and less sensitive to short term, ambient toxicity effects. 

Mass based allocations would set a definitive upper limit on the amount of each metal 

allowed to be discharged into San Diego Creek and Newport Bay, which would probably be 

most effective in addressing long term sediment toxicity concerns. However, mass-limit based 

allocations would be challenging to meet during individual wet years, although the flow tier 

approach is designed to help address this concern. Moreover, attainment of mass-based 

allocations may be more difficult to monitor. 

Concentration-based allocations accommodate the dynamic nature of freshwater systems 

with diversity of flows and individual hardness conditions. Metals concentrations are generally 

easier to monitor; however, hardness measurements would be needed in addition to metals 

concentration measurements. However, a focus solely on concentrations could result in 

compliance with concentration-based allocations and still allow metals loadings at levels that 

contribute to unacceptable downstream sediment toxicity. This option could rely on alternate 

seawater sediment targets (Table 5-3) to provide acceptable conditions for benthic organisms. 

 

TMDLs and Allocations 

The proposed TMDLs allocations are based on the mass-based approach discussed above. 

The TMDLs and allocations may be expressed in terms of the following general equation: 

TMDL = Σ (wasteloads from stormwater runoff, groundwater cleanup and dewatering 

discharges) + Σ (load from hillside runoff, agricultural runoff, atmospheric deposition and 

undefined sources) + Margin of Safety 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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San Diego Creek 

Table 5-6a identifies the proposed mass based allocations for dissolved metals from San 

Diego Creek. They are based on the chronic targets and the associated flow volume per tier. 

The total allocation has been reduced by 20% to address load associated with particulate-metals 

as discussed below in the margin of safety section. These allocations apply to the annual amount 

to be recorded at San Diego Creek at Campus Drive. Additional mass-based allocations (using 

similar calculation methods) apply to Santa Ana-Delhi Channel. 

Table 5-6a Mass-based Allocations for San Diego Creek 

Categor

y 

Type Copper Zinc Lead Cadmium 

Urban runoff 712 18,078 492 314 

CalTrans 127 1660 44 30 

Other NPDES 

permittees

106 1384 36 24 

Sub-total 945 lbs/yr 21,122 lbs/yr 572 lbs/yr 368 lbs/yr 

WLA 

 

Nurseries 140 12 0 4 

Ag runoff 7 5 0 4 

Undefined 

(natural) 

600 1,000 9 14 

Sub-total 747 lbs/yr 1017 lbs/yr 9 lbs/yr 22 lbs/yr 

LA 

 

MOS 422 lbs/yr 5535 lbs/yr 145 lbs/yr 98 lbs/yr 

 

Total 

TMDL 

 2114 lbs/yr 27,674 lbs/yr 726 lbs/yr 488 lbs/yr 

As discussed in the loading capacity section, EPA is also considering the option of 

expressing TMDLs on a concentration basis. If this alternative approach is selected in the final 

TMDLs, the freshwater allocations would be the concentration-based targets, reduced by 20% to 

provide the margin of safety discussed below (see Table 5-6b for freshwater allocations under 

this option). These alternative allocations would apply to all freshwater discharges to San Diego 

Creek, Santa Ana-Delhi Channel, Big Canyon Channel, East Costa Mesa Channel and other 

drainages. This includes discharges from agricultural, urban and residential lands, including 

flows from the storm water systems. These allocations would apply at all times of the year. 

Table 5-6b. Concentration-based Dissolved Metals Allocations for San Diego Creek (ug/L) 

Base & Small Flows 

(<42 cfs) 

hardness @ 400 mg/L 

Medium Flows 

(42 - 190 cfs) 

hardness @ 320 mg/L 

Large Flows 

(>190 cfs) 

hardness @ 190 mg/L 

Dissolved Metal Chronic Chronic Chronic 

Cd 4.96 4.2 2.9 

Cu 23.4 19.4 12.4 

Pb 8.8 7.0 4.0 

Zn 305.9 252.8 162.8 

Values are 80% of freshwater numeric targets in Table 5-2 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 47 

Newport Bay

Table 5-7a presents the proposed mass based allocations for dissolved metals in Newport 

Bay; they are not hardness dependent. These allocations apply to the water column in Upper 

Newport Bay (defined from San Diego Creek at Jamboree Rd. down to Pacific Coast Highway 

Bridge), Lower Newport Bay (defined from PCH Bridge to the Newport Jetty) and to Rhine 

Channel (defined by line drawn from 20th St. across to Lido Beach St.). These allocations apply 

to the receiving waters of Newport Bay at all times of the year, regardless of freshwater flow 

from San Diego Creek, Santa Ana-Delhi, Costa Mesa Channel and other tributaries into Newport 

Bay. It is assumed that NPDES boatyard permittees are not discharging into salt waters of 

Newport Bay, rather the boatyard effluent is contained in site sumps or re-routed to Orange 

County Sanitation District treatment plant as part of pre-treatment program. Table 5-7b presents 

the concentration-based dissolved metal allocations for Newport Bay. 

Table 5-7a. Mass-based Allocation Scheme for Metals in Newport Bay 

Category Type Copper Zinc Lead Cadmium 

Urban runoff 3204 184,908 20,237 9200 

CalTrans 121 2592 269 123 

J. Wayne Airport 60 1296 134 62 

Boatyards 0 0 0 0 

Other NPDES 

permittees 

181 3889 403 186 

Sub-total 3566 lbs/yr 192,685 lbs/yr 21,043 lbs/yr 9571 lbs/yr 

WLA 

Ag runoff 30 296 0 8 

Boats 5007 1000 0 0 

Air deposition 101 606 68 3.5 

Undefined 

(natural) 

966 12,813 400 311.5 

Sub-total 6104 lbs/yr 14,715 lbs/yr 468 lbs/yr 323 lbs/yr 

LA 

MOS 2417 lbs/yr 51,849 lbs/yr 5378 lbs/yr 2473 lbs/yr 

Total 

TMDL 

 12,087 lbs/yr 259,249 lbs/yr 26,889 lbs/yr 12,367 lbs/yr 

20% margin of safety applied to total loading capacity 

Table 5-7b. Concentration-based Dissolved metal allocations for Newport Bay (ug/L) 

Metal 

Dissolved saltwater 

chronic (ug/L) 

Cd 7.4 

Cu 2.5 

Pb 6.5 

Zn 64.8 

Values are 80% of seawater numeric targets in Table 5-3. 

Seasonal Variations/Critical Conditions 

These TMDLs rely on careful analysis of the full range of potential flow conditions to 

address seasonal variations and critical conditions in loads and flows. In general, base and low 

flows do not present conditions within San Diego Creek that result in either exceedances of 

numeric targets nor impairment. This is due to higher hardness levels during low flows that 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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mitigate metals toxicity through competitive binding by calcium and magnesium ions present in 

freshwater. 

Wet weather conditions, which may occur at any time of the year, yield medium and 

large flows and a range of hardness values. High flows are more likely to produce both low 

hardness and higher metal levels; these conditions are the biggest threat to aquatic organisms in 

San Diego Creek and its tributaries. For Newport Bay, the TMDLs address long term metals 

accumulations which are associated with metals-caused sediment toxicity measured in the Bay. 

Therefore, there is no single season or critical season of greatest concern for metals loadings and 

effects in Newport Bay. The saltwater allocations apply during all seasons, regardless of flow. 

Margin of Safety 

EPA has applied a 20% explicit margin of safety to the dissolved metals TMDLs for both 

freshwater and saltwater bodies of Newport Bay watershed. This explicit margin of safety is 

intended to account for uncertainty concerning total (particulate and dissolved) metal loads into 

San Diego Creek which are transported downstream and deposit in the sediments of Upper and 

Lower Bay, including Rhine Channel. These metals TMDLs address aquatic life toxicity due to 

concentrations in the dissolved fraction; this is consistent with current regulatory status for 

metals as defined by CTR (USEPA 2000a). In recognition of sediment toxicity in Newport Bay 

correlated to elevated metals, we have selected the 20% margin of safety based on the default 

total/dissolved metal translator provided in CTR. Our estimates of site-specific total/dissolved 

translator values are fairly close to the CTR value. It is reasonable to assume that reductions in 

the particulate metal load will achieve the concentration-based dissolved metal targets. 

In addition to the explicit margin of safety, conservative assumptions were used in 

applying the numeric targets within the watershed. These conservative assumptions provide an 

implicit margin of safety to ensure that TMDLs are set at levels that will attain applicable 

standards and protect aquatic life. 

1. The flow-based approach to determining metal loading for freshwater bodies has utilized 

the more protective chronic water quality criteria. For all flow tiers, the chronic numeric 

targets—the lowest possible value—was used to determine the appropriate water quality 

criteria. For saltwater bodies, the chronic criteria were applied at all times. 

2. No adjustment or lowering has been made to address mixing and dilution within the 

drainage channels contributing to San Diego Creek. Also, there has been no 

consideration of precipitation (forming particulate metals forms) of dissolved metals as 

freshwater mixes with saltwater. 

3. Chemical speciation has not been included within calculations of loading capacity nor 

allocations. Aquatic chemists believe the truly bioavailable metal fraction (free metal ion 

concentration) is much lower (at least 10 times) than dissolved metal concentration. This 

has been reported for Cd, Pb, Cu and Zn within freshwater and saltwater systems (Buffle 

1988, Bruland 1991, Sunda et al. 1987). 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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4. OCPFRD estimates of metal loading have used unfiltered sample results and this yields 

an overestimate since dissolved metal concentrations may be lower than total metal 

concentrations. 

5. The flow-based approach to determining metal loading for freshwater bodies has utilized 

the more protective chronic water quality criteria. For all flow tiers, the chronic numeric 

targets—the lowest possible value—was used to determine the appropriate water quality 

criteria. For saltwater bodies, the chronic criteria were applied at all times. 

6. No adjustment or lowering has been made to address mixing and dilution within the 

drainage channels contributing to San Diego Creek. Also, no allowance was made for the 

process of metals precipitation (forming particulate metals forms) of dissolved metals as 

freshwater mixes with saltwater. 

7. Chemical speciation has not been included within calculations of loading capacity nor 

allocations. The truly bioavailable metal fraction (free metal ion concentration) may be 

much lower (at least 10 times) than dissolved metal concentration. This has been 

reported for Cd, Pb, Cu and Zn within freshwater and saltwater systems (Buffle 1988, 

Bruland 1991, Sunda et al. 1987). 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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VI. Organochlorine TMDLs

TMDLs are required for chlordane, total DDT and total PCBs in all waterbodies: San 

Diego Creek, Upper Bay, Lower Bay and Rhine Channel. Dieldrin TMDLs are required for San 

Diego Creek, Lower Bay and Rhine Channel. A TMDL for toxaphene is required for San Diego 

Creek only. The term “organochlorine compounds” includes all of these pollutants; whereas, the 

phrase “organochlorine (OC) pesticides” refers to DDT, chlordane, dieldrin and toxaphene. 

Additional information on the source analysis, modeling approach and relevant monitoring 

results for these TMDLs is provided in Technical Support Document—Part F. 

Problem Statement 

Use of these pollutants has been banned because of potential harm to human health 

and/or wildlife. However, many of the environmental concerns associated with their use and 

ultimate transport to the environment are directly related to their ability to persist in water, soil, 

and biological tissue for long periods of time after their introduction to the environment. 

Monitoring results show exceedances of EPA and State fish tissue screening values, 

which indicate the narrative water quality standards discussed are not being met. Specifically, 

toxaphene exceedances (87%, n=15) of the OEHHA tissue screening value occur only in San 

Diego Creek (TSM, 2001). Bioaccumulation of PCBs, DDT, chlordane and dieldrin appears to 

be occurring in San Diego Creek and in all saltwater bodies of Newport Bay, except for dieldrin 

in Upper Bay. This conclusions is based on analysis of fish tissue results from several 

monitoring efforts (SMW, TSMP, CFCS and SCCWRP databases, see Table 2-2). A review of 

tissue data for a 20 year period indicates that fish tissue concentrations are declining for the OC 

compounds, yet exceedances of EPA and OEHHA tissue screening values are still occurring. 

The sediment concentrations do not show the same declining trend in freshwater and saltwater 

sediment results. 

Numeric Targets 

As discussed in Section II, EPA evaluated the applicable water quality criteria and 

sediment and tissue screening levels to determine the appropriate numeric targets for these 

organochlorine TMDLs. We have prioritized sediment quality guidelines over tissue screening 

values and water column criteria. This decision has been based on the following factors: 

1) these pollutants are directly associated with sediments (i.e., fine particulate 

matter); 

2) sediments are the transport mechanism for these organochlorine compounds from 

freshwaters to saltwaters; 

3) limited water column data are available to adequately describe the past or current 

conditions 

4) attainment of the sediment targets will be protective of the water column criteria. 

The use of sediment criteria in this analysis is believed to be the most protective 

interpretation of water quality criteria and the sediment targets will serve as the optimal 

interpretation of the narrative water quality objectives established by Regional Board Basin Plan 

(1995). 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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The numeric targets for freshwater and saltwater systems for chlordane, dieldrin, DDT, 

PCBs and toxaphene, are shown in Table 6-1. The primary target value is based on sediment 

levels, and the alternate targets are provided for fish and shellfish tissues. The specific numeric 

values for sediment targets were selected from Florida Dept. of Environmental Protection 

(MacDonald et al. 1996) as previously discussed in Section II of this summary document. By 

selecting sediment targets, EPA will address protection of aquatic and benthic organisms as well 

as bioaccumulation of these organochlorine compounds into tissues of higher organisms such as 

fish, wildlife predators and humans. Sediment targets will be used for TMDL development 

except where sediment data were not available; e.g., toxaphene in San Diego Creek. The 

alternate targets—fish tissue values from New York Dept. of Environmental Conservation—are 

included in this TMDL report as means of gauging improvement in the water quality and 

progress towards achievement of the TMDL, and also because they directly relate to the human 

health water quality objective. [Note sediment values are presented in dry weight units whereas 

fish tissue values are wet weight basis.] 

Table 6-1. Numeric targets for organochlorine compounds for all waterbodies. 

Waterbody Analyte Sediment target@ 

(ug/dry kg) 

Fish tissue target 

(ug/g wet) 

Chlordane 2.26 0.5 

Dieldrin 0.71 0.12 

Total DDT 1.19 0.2 

Total PCBs 21.5 0.11 

San Diego Creek 

and tributaries 

Toxaphene 0.1* 6.3 

 

Chlordane 2.26 0.5 

Dieldrin 0.71 0.12 

Total DDT 1.19 0.2 

Upper and Lower 

Newport Bay, 

and Rhine 

Channel Total PCBs 21.5 0.11 

*this value assumes 1% total organic carbon in sediment sample 

@sediment targets equal to threshold effect levels (TEL) from MacDonald et al. 1996 

all tissue targets from NY Dept. Environmental Conservation 

Source Analysis 

Except for PCBs and possibly small amounts of DDT, the pollutants addressed in this 

TMDL are no longer believed to be discharged in the watershed; therefore the source analysis is 

primarily a qualitative assessment. The assessment is based on reviews of available information 

on the physical and chemical properties of each chemical, the expected uses of each, the likely 

locations of use, and available monitoring data that characterizes current conditions in the 

environment. A wide range of information was evaluated to identify potential sources and to 

characterize contributions, including monitoring data, data from national, state and county 

program databases, and scientific literature. More details on the efforts to identify and 

characterize potential sources of organochlorine compounds are provided in the Technical 

Support Document—Part F. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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The main source of organochlorine compounds in the Newport Bay watershed is believed 

to be surface soils or in-stream sediments to which these pollutants have adsorbed (binded). 

Sediment-adsorbed pollutants are believed to enter Newport Bay from San Diego Creek (88%) 

and various smaller tributaries and local drainages (12%). The sediment load is then distributed 

throughout Newport Bay via internal circulation patterns under a variety of flow conditions. In 

preliminary results from one sampling event of sub-surface waters in Lower Bay, SCCWRP 

(2001a) reported detections of total PCBs and DDT. At the Turning Basin, these compounds 

were associated with particulate matter (PCBs = 8.86 ug/kg dry; DDT = 15.3 ug/kg dry) and in 

the dissolved phase (PCBs = 0.15 ng/L; DDT 0.43 ng/L). Dieldrin and Chlordane were not 

detected. 

These organochlorine compounds may also exist in groundwater (due to percolation), 

may transport via volatilization (from surface soils or water surface) and as implied above they 

may become resuspended into the water column via physical processes in water bodies. Without 

sufficient local analytical data, it is difficult to quantify these sources, yet this may be revisited in 

the future. 

Organochlorine (OC) pesticides 

Because of the legacy nature of the sources of the OC pesticides, assessment of possible 

nonpoint sources of these types of pollutants has been based on a review of available monitoring 

data, historical land use practices, literature reviews, and anecdotal information. One of the 

major routes for the OC compounds to enter Newport Bay and its tributaries is believed to be 

runoff and erosion processes. Two researchers, Masters and Inman (1998), have examined 

fluvial transport of DDT and other legacy pesticides in Upper Newport Bay; they hypothesize 

that historic agricultural and urban applications of these compounds are the primary upstream 

sources. In general, these runoff and erosion processes have the ability to pick up and transport 

these OC pesticides and deposit them in a different location in the watershed, to a stream system, 

or to the Bay. The amount of transport and the locations of deposition depend on many factors, 

including the presence of the pollutant and the intensity and duration of the precipitation event, 

which drives stream flow velocity and possibly direction. Because organochlorine residuals 

from past applications still remain in soils, the potential still exists for these chemicals (and their 

degraded metabolites) to be transported into water bodies during runoff-producing rainfall 

events. Insufficient information exists on the specific location and actual magnitude of these 

sources to support precise loading estimates; therefore, we inferred existing loadings based on 

limited data and we estimated the pollutant distributions amongst many diffuse sources. 

The only active source of any of the OC pesticides is the application of Dicofol, a 

registered pesticide that contains small amounts of DDT (i.e., up to .015%). The DPR pesticide 

use database reveals that Dicofol (trade name “Kelthane”) has been recently applied to 

agricultural fields within the Newport Bay watershed (502 lbs. in 1998 and 470 lbs. in 1999). 

Relative to other sources of DDT (i.e., residuals in soils), Dicofol is not estimated to be a 

significant source of DDT to Newport Bay; nonetheless future use of this pesticide must be 

minimized

Polychlorinated biphenyls (PCBs) 

Electrical transformers are the most common use of PCBs. Existing PCB projects such 

as the Hudson River project in New York and the Housatonic River project in Massachusetts 

have found that historical discharges have resulted in sediment contamination and that the 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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contaminated soils tend to collect in slow river stretches or reservoirs (GE 1999). The 

contaminated soils remain there until they are dredged or dislodged by storms. Releases of PCBs 

into the San Diego Creek and Newport Bay watersheds could have resulted from accidental PCB 

spills, especially those located in the El Toro and Tustin Air Stations as well as other hazardous 

waste sites. Insufficient information exists on the specific location and actual magnitude of these 

sources, thus we inferred existing loadings based on limited data and we estimated the pollutant 

distributions amongst many diffuse sources. 

Modeling and Analysis 

A sediment deposition budget model was developed for these toxics TMDLs. This 

sediment model was based on hydrologic and modeling information previously compiled by 

Resource Management Associates (RMA 1997, 1998, 1999) for the U.S. Army Corp of 

Engineers (ACOE). Modeling and data analysis were used to derive linkages between selected 

target values, loading capacity, and allowable loading for each critical area of the receiving 

waters. Additional analyses were used to derive the time required to meet numeric targets if the 

long-term loading is maintained at or below the allowable loading. If, in future years, the actual 

pollutant discharges are below the allowable loading, this would potentially expedite compliance 

with numeric targets and associated water quality objectives. 

A relatively simple approach was employed to link the bottom sediment conditions with 

the water column pollutant concentrations and where necessary mussel (or fish) tissue 

concentrations. Site-specific bioconcentration factors (BCFs) and biota-sediment accumulation 

factors (BSAFs) were calculated and applied for each compound. In this manner, the sediment 

deposition budget model was interconnected to the physical and chemical interactions within a 

specific location of Newport Bay. This approach was calibrated using all available monitoring 

data. The calibrated model was then used to calculate allowable loadings associated with the 

water column so that bottom sediment or appropriate tissue targets will ultimately be attained. 

Detailed descriptions of the modeling analysis are provided in Technical Support Document—

Part F. The modeling analysis included estimates of existing loadings, estimates of current 

sediment accumulation rates, derivation of relationships between tissue/mussel data and 

sediment concentration of key pollutants, estimates of pollutant accumulation, and conditions in 

deposited sediments over time. 

Loading Capacity/Linkage Analysis 

The loading capacity for each pollutant was calculated for San Diego Creek and 

representative critical areas of Newport Bay. Each loading capacity was derived using a 

combination of analyses described briefly below and explained more thoroughly in the Technical 

Support Document—Part F. Selection of the appropriate technique and assumptions was 

dependent on the data available for each pollutant type and location. In most cases, we used the 

sediment target concentrations to calculate the associated water column concentrations and 

corresponding mussel tissue concentrations which were typically below the alternate tissue 

targets. However, in some cases we needed to work backwards from tissue to water to sediment 

to determine if the sediment targets would be met. The OC compound loading capacities for 

San Diego Creek and Newport Bay are listed in Tables 6-2 and 6-3, respectively. To assist the 

reader, some references to specific tables in TSD—Part F are included here. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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For the listed OC pollutants in San Diego Creek the loading capacities were calculated 

based on both water-column criteria and identified sediment target endpoints. Partition 

coefficients were used to estimate the particulate-associated portion of the pollutant load. Using 

bottom sediment targets as an endpoint, the appropriate water-column concentration can be backcalculated to determine the loading capacity. The particulate loading associated with the water 

column will then result in meeting the sediment target when it settles to the bottom. The 

resulting loading capacities are listed in Table 6-2 (and F-8 of TSD). Loading capacities are 

presented as long term annual loading consistent with the patterns of sediment deposition in the 

system. The loading capacity for San Diego Creek is estimated from analysis of historic flow 

records (USGS data, 1985 to 2000) and in-stream concentrations. 

Based on the loading potential and an estimate of the distribution of sediment deposition, 

the loading capacity for Newport Bay was estimated for Upper Bay, Lower Bay and Rhine 

Channel. The loading capacities for these areas within Newport Bay are estimated using the 

previously described sediment deposition budget model developed for this TMDL and the 

appropriate sediment (or tissue) target values. Previous modeling studies have examined the 

circulation patterns, and transport and deposition of sediments in Newport Bay (RMA 1998). By 

examining RMA model calibration results for Newport Bay from 1985-1997, the sediment 

deposition in each critical area of Newport Bay can be estimated (Table F-9 of TSD). Historic 

pollutant loads to the bottom sediment can be approximated by using observed pollutant 

concentrations in bottom sediments and net sedimentation rates (see Table F-10). Estimated 

loading capacity for Newport Bay is based on the desired sediment targets as opposed to the 

observed pollutant concentrations, see Table 6-3 below (and Table F-11 in TSD). Sediment 

volume is converted to dry weight by use of an estimated porosity (0.55). The loading capacities 

are presented as average mass per year to reflect the long-term accumulation patterns associated 

with sediment and pollutant accumulation in Newport Bay. 

The loading capacity was determined using the model discussed in the TSD and in the 

“Modeling and Analysis” section of the summary document, in order to determine the maximum 

amount of loading which could occur and still result in attainment of the sediment targets. The 

model, as discussed, links source contributions to pollutant concentrations in bottom sediments 

and predicts the trend of pollutants in the sediment. The model takes into consideration such 

factors as the existing water column concentrations (either observed or calculated from the tissue 

concentrations in mussels), data and modeling of sediment deposition into the waterbodies, 

decay rate for a pollutant in the water column, thickness of the water column and active sediment 

layer, resuspension rate and burial rate. 

Table 6-2. Estimated Loading Capacity for San Diego Creek 

Pollutant 

Name 

Water Column* 

Total Concentration 

(ug/L) 

Load capacity 

(g/year) 

Chlordane 0.00147 71.80 

Dieldrin 0.00060 29.31 

DDT@ 0.00100 48.84 

PCBs 0.001058 341.9 

Toxaphene 0.000086 4.20 

*All values derived from State Mussel Watch data (1984-1993) at Macarthur Blvd. 

@DDT value from observed data (SCCWRP 2001a) 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Table 6-3. Estimated Loading Capacity for Newport Bay 

Sediment Target 

Concentration (ug/kg dry) 

Loading Capacity 

(g/year) 

Waterbody Chlordane Dieldrin DDT PCBs Chlordane Dieldrin DDT PCBs 

Upper Bay 2.26 0.71 1.19 21.5 162.92 N/A 85.78 1513.81 

Lower Bay* 2.26 0.71 1.19 21.5 59.18 18.59 31.16 229.36 

Rhine 

Channel 2.26 0.71 1.19 21.5 1.70 0.53 0.89 15.79 

(This table is summary of information presented in Table F-11 in TSD—Part F.) 

TMDLs and Allocations 

For these organochlorine TMDLs, we have expressed the TMDLs and allocations in 

mass-based units (grams per year) for each waterbody. Identification of the TMDLs is based on 

consideration of the historic or existing loading (based on observed mussel or suspended 

sediment concentrations) versus the estimated loading capacity (based on sediment targets), and 

current conditions in the areas of concern. The sum of allocations for each compound in each 

waterbody segment is summed to equal the loading capacity. In situations where existing 

loadings are less than the TMDLs, we expect water quality standards to be attained eventually 

without further loading reductions. However, given the potential for adverse environmental 

impacts associated with these compounds, it is important to minimize any future discharges to 

the watershed. In reviewing the conditions present for each pollutant and waterbody we 

identified two possible conditions (see Table 6-4) under which the load allocation would be 

selected. A 10% margin of safety is included. The following discrete conditions were identified: 

Condition 1: If existing conditions will meet sediment targets, no additional reduction is 

applied. Allocation = Existing Loading – MOS. No load increase is allowed. 

Condition 2: If existing conditions do not meet sediment targets, then reduction is required. 

Allocation = Loading Capacity – MOS 

Table 6-4. Summary of condition applicable to each waterbody/pollutant combination. 

Pollutant San Diego 

Creek 

Upper 

Newport Bay 

Lower 

Newport Bay 

Rhine Channel

Chlordane Condition 2 Condition 1 Condition 2 Condition 2 

Dieldrin Condition 2 NL Condition 2 Condition 2 

DDT Condition 2 Condition 2 Condition 2 Condition 2 

PCBs Condition 1 Condition 1 Condition 2 Condition 2 

Toxaphene Condition 2 NL NL NL 

NL: Not listed for this pollutant 

Existing loadings of many of the pollutants appears to be declining over time as historic 

accumulations degrade or are transported through San Diego Creek to Newport Bay and the 

ocean. Examination of long-term records (1980-2000) indicate that the average organochlorine 

compound concentrations in mussel tissues in San Diego Creek and Newport Bay have declined 

80 percent and 70 percent, respectively, during that time. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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The load allocation was derived using the sediment deposition model for each of the 

critical areas. Two analytical methods were applied depending on available data and the type of 

endpoint used. The first method, applied to San Diego Creek, calculates long-term sediment 

loading, derived from observed sediment concentrations (300 mg/L on average), and long term 

flow records (USGS data). Using the appropriate partition coefficients for each pollutant, the 

water column concentration and associated OC pollutant loading can be estimated. 

The second method uses recent mussel tissue data (SMW 1993—1998 data) to estimate 

existing water column concentrations for selected pollutants in each critical area in Newport Bay 

(including Rhine Channel). The average concentrations for each area are calculated. By using 

the sediment target, the water column concentrations can also be calculated. When comparing 

these two independently estimated concentrations, the lower concentration is used as water 

column concentration. 

Tables 6-5 through 6-8 summarize the existing loads, the estimated loading capacity, and 

the total allocation for each pollutant with respect to each waterbody. Values for Upper and 

Lower Bay represent the sum of several critical areas each, as defined in TSD—Part F, section 4. 

The time to meet water quality standards for each pollutant with respect to each waterbody is 

included as an approximation. The time (in years) is a slight overestimate since it is based on the 

loading capacity prior to subtracting the margin of safety. Therefore, if the annual load 

allocations are strictly adhered, it would take slightly less time to meet the desired target. 

Table 6-5. Summary of San Diego Creek Loadings and Allocations (g/year) 

Pollutant Existing 

Load 

(g/year) 

Loading 

Capacity 

(g/year) 

Total 

Allocation 

(g/year) 

Margin of 

Safety 

(g/year) 

Approximate 

time to Meet 

Target 

(Year) 

Chlordane 109.52 71.80 64.62 7.18 8 

Dieldrin 39.71 29.31 26.38 2.93 S 

DDT 271.64 48.84 43.96 4.88 S 

PCBs 144.58 341.9 130.12 14.46 9 

Toxaphene 378.82 4.20 3.78 0.42 15 

S = satisfied; i.e., already meets numeric target 

Total allocation + Margin of Safety = lesser value in existing load or loading capacity 

Table 6-6. Summary of Upper Newport Bay Loadings and Allocations 

Pollutant Existing 

Load 

(g/year) 

Loading 

Capacity 

(g/year) 

Total 

Allocation 

(g/year) 

Margin of 

Safety 

(g/year) 

Approximate 

time to Meet 

Target 

(Year) 

Chlordane1 128.25 162.92 115.43 12.82 S 

DDT2 1273.12 85.78 77.20 8.58 12 

PCBs1 445.09 1513.81 400.58 44.51 0.5 

1 existing load based on SMW data (1993-1998) 

2 existing load based on observed particulate water concentration (SCCWRP 2001a) 

S = satisfied; i.e., already meets numeric target 

Total allocation + Margin of Safety = lesser value in existing load or loading capacity 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Table 6-7. Summary of Lower Newport Bay Loadings and Allocations 

Pollutant Existing 

Load 

(g/year) 

Loading 

Capacity 

(g/year) 

Total 

Allocation 

(g/year) 

Margin of 

Safety 

(g/year) 

Approximate 

time to Meet 

Target 

(Year) 

Chlordane1 103.28 59.18 53.26 5.92 17 

Dieldrin1 46.13 18.59 16.73 1.86 1 

DDT2 1183.49 31.16 28.04 3.12 1.3 

PCBs1 844.97 229.36 206.42 22.94 5 

1 existing load based on SMW data (1993-1998) 

2 existing load based on observed particulate water concentration (SCCWRP 2001a) 

Total allocation + Margin of Safety = lesser value in existing load or loading capacity 

Table 6-8. Summary of Rhine Channel Loadings and Allocations 

Pollutant Existing 

Load 

(g/year) 

Loading 

Capacity 

(g/year) 

Total 

Allocation 

(g/year) 

Margin of 

Safety 

(g/year) 

Approximate 

time to Meet 

Target 

(Year) 

Chlordane1 1.77 1.58 1.53 0.17 18 

Dieldrin1 3.76 0.53 0.48 0.05 3 

DDT2 8.48 0.89 0.80 0.09 4 

PCBs1 57.85 15.79 14.21 1.58 7 

1 existing load based on SMW data (1993-1998) 

2 existing load based on observed particulate water concentration (SCCWRP 2001a) 

Total allocation + Margin of Safety = lesser value in existing load or loading capacity 

Tables 6-9, 6-10, 6-11, and 6-12 summarize the allocations for each OC pollutantwaterbody combination. The explicit margin of safety (10%) has been included for clarification. 

Table 6-9. Allocation scheme for San Diego Creek watershed 

Category Type DDT (including 

Dicofol) 

Chlordane Dieldrin PCBs Toxaphene 

Urban 

runoff 

35.5 60 24.3 110.5 3.0 

Other 

NPDES 

permittees 

0 0 0 5.2 0 

Sub-total 35.5 g/yr 60 g/yr 24.3 g/yr 116.7 g/yr 3.0 g/yr

WLA 

 

Nurseries 4 0 0 0 0 

Other ag 3 0 0 0 0 

Undefined 1.5 5 2 14.3 0.8 

Sub-total 1.5 g/yr 5 g/yr 2 g/yr 14.3 g/yr 0.8 g/yr

LA 

MOS 5 g/yr 7 g/yr 3 g/yr 14 g/yr 0.4 g/yr

Total 

TMDL 

 49 g/yr 72 g/yr 29.3 g/yr 144 g/yr 4.2 g/yr

Total TMDL = WLA + LA + MOS 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Table 6-10. Allocation scheme for Upper Newport Bay 

Category Type DDT (including 

dicofol) 

Chlordane PCBs 

Urban runoff 65.6 108.8 369 

Other NPDES 

permittees 

 3.1 0 16 

Sub-total 68.7 g/yr 108.8 g/yr 385 g/yr

WLA 

 

Ag discharges 5.4 0 0 

Undefined 3.1 6.4 15.5 

Sub-total 8.5 g/yr 6.4 g/yr 15.5 g/yr

LA 

MOS 8.6 g/yr 12.8 g/yr 44.5 g/yr

Total TMDL 85.8 g/yr 128 g/yr 445 g/yr

Total TMDL = WLA + LA + MOS 

Table 6-11. Allocation scheme for Lower Newport Bay 

Category Type DDT (including 

dicofol) 

Chlordane Dieldrin PCBs 

Urban runoff 25.5 49.2 15.4 183.6 

Other NPDES 

permittees 

 1.3 0 0 0 

Sub-total 26.8 g/yr 49.2 g/yr 15.4 g/yr 183.6 g/yr 

WLA 

 

Ag discharges 0 0 0 0 

Undefined 1.3 4.1 1.3 22.9 

Sub-total 1.3 g/yr 4.1 g/yr 1.3 g/yr 22.9 g/yr 

LA 

MOS 3.1 g/yr 5.9 g/yr 1.9 g/yr 22.9 g/yr 

Total TMDL 31.2 g/yr 59.2 g/yr 18.6 g/yr 229.4 g/yr 

Total TMDL = WLA + LA + MOS 

Table 6-12. Allocation scheme for Rhine Channel within Lower Newport Bay 

Category Type DDT (including 

dicofol) 

Chlordane Dieldrin PCBs 

Urban runoff 0.77 1.4 0.46 12.6 

Other NPDES 

permittees 

0 0 0 0 

Sub-total 0.77 g/yr 1.4 g/yr 0.46 g/yr 12.6 g/yr 

WLA 

 

Ag discharges 0 0 0 0 

Undefined 0.03 0.1 0.02 1.6 

Sub-total 0.03 g/yr 0.1 g/yr 0.02 g/yr 1.6 g/yr 

LA 

MOS 0.09 g/yr 0.2 g/yr 0.05 g/yr 1.6 g/yr 

Total TMDL 0.89 g/yr 1.7 g/yr 0.53 g/yr 15.8 g/yr 

Total TMDL = WLA + LA + MOS 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Margin of Safety 

EPA has applied an explicit 10% margin of safety to the loading capacity for these OC 

TMDLs. The specific mass-based margin of safety for each pollutant with respect to each 

waterbody is included in Tables 6-5, 6-6, 6-7 and 6-8. This margin of safety will provide 

additional protection for aquatic life, wildlife predators and human health. 

A number of assumptions were used in the derivation of each TMDL. Insufficient 

information is available to quantify the potential uncertainty associated with each of the 

assumptions used in the analysis. The parameters used in analysis were based on best available 

information and were selected to be conservative (i.e., most protective) where possible. The use 

of an explicit margin of safety and subsequent follow-up monitoring is intended to ensure that 

numeric targets are successfully achieved and that the adequacy of the load allocation is 

evaluated over time. Key areas of uncertainty recognized in the margin of safety include the 

following: 

• The loading capacity is calculated as a long-term annual average that results in meeting 

water quality standards (expressed as sediment, water column, and/or tissue targets). 

Because the analysis is focused on long-term predictions, periodic fluctuations are not 

represented, and actual loading may differ in the short-term. 

• Long-term sediment deposition patterns were used to calculate the total amount of 

sediment deposited in each region. This long-term average value does not represent 

short-term or localized fluctuations in deposition rates. Periodic accumulation or 

scouring could be significant during large storm events. This could result in higher or 

lower deposition rates than the predicted sediment deposition and pollutant 

concentrations. 

• A constant suspended sediment concentration (300 mg/L) was used to calculate the 

loading capacity for San Diego Creek. In the short-term sediment concentration will vary 

resulting in potentially higher or lower loadings to the Creek and Newport Bay. 

• A constant sediment porosity value was used to calculate loads associated with deposited 

sediment. Sediment porosity values used in the model to estimate loading capacity for 

San Diego Creek and Newport Bay (0.55) were slightly lower than those used for 

historical loads (0.65). No sediment consolidation was assumed. This resulted in a 

conservative assumption, since consolidation would result in a lower porosity, which 

would increase the load associated with deposited sediment. 

Seasonal variation/Critical conditions 

These TMDLs rely on careful analysis of the full range of potential flow conditions to 

address seasonal variation and critical conditions in loads and flows. The sediment transport and 

deposition within each waterbody is driven by the velocity and sheer conditions of flow. The 

annual deposition is accounted for by using the sediment model developed by RMA (1997, 98, 

99) which incorporates various flow regimes throughout each year. The model represents 

various weather patterns and flow conditions for 25 years. (See Figure F-3 in TSD Part F.) 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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Obviously the wet weather events, which may occur at any time of the year, produce 

extensive sediment redistribution and transport downstream. This would be considered the 

critical condition for loading. However, the effects of OP compounds are manifested over long 

time periods in response to bioaccumulation in the food chain. Therefore, short term loading 

variations are not likely to cause significant variations in beneficial use effects. 

Table 7-6. Allocation Scheme for Hg and Cr in Rhine Channel 

Category Type Mercury Chromium 

Urban runoff 0.013 1.19 

CalTrans 0.0008 0.446 

J. Wayne Airport 0.0004 0.297 

Boatyards 0 0 

Other NPDES permittees 0.0012 0.297 

Sub-total 0.0154 kg/yr 2.23 kg/yr 

Existing sediments 0.063 26.80 

Undefined 0.0016 0.74 

Sub-total 0.0646 kg/yr 27.54 kg/yr 

WLA 

MOS 0.01 kg/yr 3.30 kg/yr 

Total TMDL 0.09 kg/yr 33.08 kg/yr 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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VII. Chromium and Mercury TMDLs 

TMDLs are required for chromium (Cr) and mercury (Hg) for the Rhine Channel area of 

Lower Newport Bay only. Additional information on the source analysis, modeling approach 

and relevant monitoring results for these TMDLs is provided in Technical Support Document—

Part G. 

Problem Statement 

Chromium—Chromium levels are elevated in Rhine Channel mussel tissue samples over the 

tissue screening value (1.0 mg/kg wet) used in the mussel water program, thus some 

bioaccumulation is evident (31%, n= 13). Chromium in Rhine Channel sediments are 

occasionally (8%, n= 13) above the sediment quality guideline (52 mg/kg dry). 

Mercury—Mercury sediment concentrations in Rhine Channel are above sediment quality 

guidelines levels associated with negative impacts on benthic organisms in all samples tested 

(100%, n=7). These excessive sediment concentrations (more than tenfold greater than these 

sediment guidelines) may be causing toxicity or contributing to conditions threatening aquatic 

life within Rhine Channel. However, mussel tissue concentrations were not above the EPA 

tissue screening value (0.3 mg/kg wet methylmercury), and there is no current evidence that 

mercury has bioaccumulated to levels of concern. 

Numeric Targets 

The numeric targets for chromium and mercury in Rhine Channel are presented in Table 

7-1. Two targets are provided for each chemical, one for sediment and one for tissue levels. The 

primary target value (sediment) is for TMDL development, whereas the alternate target (tissue) 

is designed to provide another means of assessing desired water quality conditions of Rhine 

Channel. 

There are several available screening values for mercury concentrations in sediment and 

fish tissue. For mercury in Rhine Channel, EPA proposes the sediment numeric target, 0.13 

mg/dry kg, as the most appropriate indicator of desired water quality. This threshold effect level 

(TEL) is associated with no observed effect on benthic organisms as part of a study by Florida 

Dept. of Environmental Protection (MacDonald et al. 1996). For comparison, the TEL value is 

much lower than the probable effects level (PEL = 0.696 mg/kg dry). This TEL value is slightly 

lower than NOAA Effects Range-Low value for mercury (ERL = 0.15 mg/kg dry). The alternate 

mercury numeric target is fish tissue (0.3 mg/kg wet methylmercury), based on analysis provided 

the Biological Opinion on the CTR by USFWS (2000). This methylmercury target is designed to 

protect human health, yet it will also be effective at reducing impacts to wildlife predators due to 

bioaccumulation. 

EPA has also evaluated the available water quality criteria and levels for sediments and 

fish tissue to determine the appropriate numeric target for chromium TMDL in Rhine Channel. 

EPA selected the sediment target (52 mg/kg dry, from MacDonald et al. 1996) as the optimal 

mechanism to protect both wildlife predators and benthic organisms. The alternate chromium 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 62 

numeric target is fish tissue, 0.2 mg/kg wet (USFWS 2001). This fish tissue target is more 

stringent than the screening value used to evaluate State mussel watch data in order to ensure 

protection of wildlife predators. 

Table 7-1. Numeric targets for Chromium and Mercury in Rhine Channel. 

Waterbody Analyte Sediment target 

(mg/kg dry) 

Alternate 

Fish tissue target 

(mg/kg wet) 

Rhine Channel Chromium (Cr) 52 0.2 

Rhine Channel Mercury (Hg) 0.13 0.3* 

*mercury tissue target is interpreted as 0.3 mg/kg wet methylmercury (USFWS 2000) 

Source Analysis 

Chromium (Cr) 

Probable sources of chromium include the heavily contaminated sediments existing in 

Rhine Channel, previous discharges by metal plating facilities near Rhine Channel, historic 

deposits in the San Diego Creek watershed and atmospheric deposition. Chromium may also be 

leaching from treated wood pylons in marine areas (Weis et al. 1991). Chromium is a naturally 

occurring element, which can be found in volcanic dust and gases. However, chromium 

emissions can also come from commercial and industrial facilities, resulting in chromium 

discharges into the atmosphere. Currently, there is not sufficient information to estimate 

chromium atmospheric deposition rates in the Newport Bay watershed. Presumably the heavily 

contaminated sediments are due to historic activities in and around Rhine Channel and these 

legacy sources have created the largest current source of chromium—the existing sediments. 

Mercury (Hg) 

No investigation has been completed to explain elevated (total) mercury sediment 

concentrations within Rhine Channel. Orange County Coastkeeper (1999) measured mercury 

concentrations in one sediment core and the results provide historical perspective. Total mercury 

results show lowest concentrations at the core top (3.4 mg/kg dry) and highest concentrations (11 

mg/kg dry) at the bottom of the one foot long core. Other researchers have found similar 

sediment concentrations in Rhine Channel; SCCWRP (2001a) reports 5.3 mg/kg dry and BPTCP 

(1997) reports (8.7 mg/kg dry) for surface (top six inches) sediment samples. Perhaps historical 

uses of ship anti-fouling paints which contained mercury are responsible for elevated sediment 

levels based on previous activities in Rhine Channel (Regional Board 1998). Most likely the 

existing sediments are the largest sources of mercury in Rhine Channel. 

Another potential source of mercury may be from mining operations at the old Red Hill 

mine in the western part of San Diego Creek watershed (in Tustin). Historic records show 

mercury mining and processing occurred at Red Hill mine between 1880 and 1939 (CA Division 

of Mines 1976). The total amount of mercury produced is not known. Mine shafts were sealed 

off in 1976, though some shafts are still open and can receive storm runoff. The Red Hill mine is 

upgradient of the Swamp of Frogs and mine drainage would have been attributed to Peters 

Canyon Wash. Other minor sources of Hg deposits have been mapped in the area. At this time, 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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no additional information is available to accurately interpret sediment transport processes from 

this historic mining site down to Rhine Channel. 

Based on water column measurements (IRWD 1999) of dissolved mercury (Hg) and 

chromium (Cr), the loads from San Diego Creek can be estimated. Analysis of previous 

hydrologic modeling studies for Newport Bay (RMA 1997), yields estimates of sediment 

transported from San Diego Creek to be deposited in the Rhine Channel annually (approx 6%). 

Assuming that most of the chromium and mercury is adsorbed by suspended sediment, the 

estimated annual loads for chromium and mercury from San Diego Creek that are delivered to 

Rhine Channel are about 46.9 g/year and 0.054 kg/year, respectively (Table 7-2). 

Table 7-2. Estimated Mercury and Chromium Loads from San Diego Creek. 

Pollutant 

Name 

Year Water Column 

Conc. (ug/L) 

Estimated Load 

to Newport Bay 

(kg/yr) 

Estimated Load 

to Rhine Channel 

(kg/yr) 

Cr ‘97-99 16 781.5 46.9 

Hg ‘97-99 0.0186 0.91 0.054 

(source: water (IRWD 1999); sediment budget (RMA 1997, 1998) 

Atmospheric deposition probably is contributing small amounts of mercury to the 

watershed; however, there are no likely nearby sources upwind of the watershed. In any event, 

atmospheric deposition is estimated to contribute very small amounts of mercury to Rhine 

Channel relative to the amounts of mercury in existing Rhine sediments as well as freshwater 

sediment deposition. Ambient seawater concentrations of mercury are extremely low, typically 

less than 1 ng/L. 

Modeling 

A bottom sediment model was developed to link water column concentrations to bottom 

sediment conditions for Hg and Cr in Rhine Channel. The sediment model algorithms and 

approach were similar to the model utilized for organochlorine compounds. (Technical Support 

Document—Part F, sections 5 and 6 give more thorough description of this bottom sediment 

model.) The model was applied to Rhine Channel to evaluate the response to long-term loadings 

and estimate the loading capacity. The initial bottom sediment condition was determined from 

local data. Because no water column concentrations are available for Hg and Cr (all values are 

below detection limits), the water column concentration for model calibration was estimated 

from the bioaccumulation factor derived for San Diego Creek. Mean values of mussel and 

sediment concentrations of Cr and Hg (SMW 1980-1997) were used to estimate the 

bioaccumulation factor. The mean value of mussel data obtained from the Rhine Channel was 

used to estimate water column concentration. The estimated water column concentrations 

together with observed mussel data were used for the model calibration (Table 7-3). The 

partitioning coefficients for metals are not well documented; the potential values range from 0.1 

to 0.00001. To estimate the fraction of dissolved pollutants from the total (unfiltered) 

concentration, we estimated 0.8 for both Hg and Cr (Thomann and Mueller 1987). This is 

consistent with the first order approach applied to these TMDLs. Atmospheric deposition of 

mercury and chromium was not explicitly modeled in this analysis, but is believed to be 

insignificant as discussed above. Instead, the model used total water column concentrations, 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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which serve as an integrator of atmospheric and other loadings. The calibration results are 

shown in Figures G-1 and G-2 of TSD—Part G. 

Table 7-3. Estimated Water Column Concentration Used For Model Calibration 

Pollutant Mussel conc.* 

(mg/kg wet) 

Water conc. 

 (ug/L) 

Cr 0.62 21.31 

Hg 0.07 7.13 

*Mussel data from SMW database; water column conc derived from mussel data 

Loading Capacity/Linkage Analysis 

These TMDLs express the loading capacity and allocations in mass terms for Rhine 

Channel. These mass limits are intended not only to attain numeric targets but also to reduce 

bioconcentration of chromium in mussels and minimize any bioaccumulation of mercury in all 

wildlife and humans. Again, due to the legacy nature of these metals within Rhine Channel 

sediments, it will be necessary to address that most significant metals source- contaminated 

sediments-- to resolve any toxicity to benthic organisms associated with these heavily 

contaminated sediments. 

The loading capacities for Rhine Channel were estimated from the sediment budget 

analysis and the sediment target. The method used to calculate the loading capacities is similar 

to the method used for the organochlorine compounds. For both chromium and mercury, the 

ongoing loads, which are associated principally with local contaminated sediments, are higher 

than the estimated loading capacity. Therefore, the TMDLs and associated allocations are set 

based on this loading capacity. The loading capacities for chromium and mercury, and hence the 

TMDLs, are 33.08 kg/yr and 0.10 kg/yr respectively, expressed as annual averages (Table 7-4). 

Table 7-4. Historical Loading and Estimated Loading Capacity for Rhine Channel 

Pollutant Historical conc. *

(mg/kg dry) 

Historical Load 

(kg/yr) 

Sediment Target 

(mg/kg dry) 

Estimated Loading 

Capacity 

(kg/yr) 

Chromium 44 38.79 52 33.08 

Mercury 5.2 3.87 0.13 0.10 

* historical conc. source: Coastkeeper (1999) 

TMDL and Allocations 

For these TMDLs, EPA has calculated both wasteload allocations (WLA) and load 

allocations (LA). Inputs from historically deposited sediments and atmospheric deposition are 

included in load allocations. Ongoing sediment deposition (containing mercury and chromium) 

from San Diego Creek is addressed as a wasteload allocation because this source is generally 

subject to coverage under the existing NPDES stormwater permit. The generic TMDL equation 

is presented below with substitution for these sources of mercury. 

TMDL = Σ (wasteload allocations) + Σ (load allocations) + Margin of Safety 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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The sediment model developed for Rhine Channel was used to estimate the time required 

to meet the sediment target with a specified water column concentration and associated loading. 

The water column concentration for chromium observed in 2001 (16.0 ug/L from IRWD 1999?) 

was used to estimate the time required to meet the target value under these loading conditions. 

The water column concentration for mercury was calculated by using back-calculation from both 

the sediment target and detection limits. The detection limit presumes that existing loading is at 

or below the identified detection limit (0.0186 ug/L, IRWD 1999). An average sediment 

concentration of 300mg/l was assumed and used to estimate the particulate-associated mercury 

and chromium. For mercury the detection limit was selected as the basis for the load allocation 

since this represents a value closer to existing conditions and results in more expeditiously 

meeting water quality standards. For both chromium and mercury, the estimated loading 

capacity for Rhine Channel equals the TMDLs, and therefore the sum of total allocations and 

margin of safety (Table 7-5). 

Table 7-5. Rhine Channel Allocations 

Pollutant 

Total Allocation 

(kg/year) 

Margin of Safety 

(kg/yr) 

Approximate time 

to meet target 

(year) 

Cr 29.78 3.30 < 1 

Hg 0.09 0.01 18 

Total Allocation + Margin of Safety = estimated loading capacity 

Table 7-6. Allocation Scheme for Hg and Cr in Rhine Channel 

Category Type Mercury Chromium 

Urban runoff 0.013 1.19 

CalTrans 0.0008 0.446 

J. Wayne Airport 0.0004 0.297 

Boatyards 0 0 

Other NPDES permittees 0.0012 0.297 

Sub-total 0.0154 kg/yr 2.23 kg/yr 

Existing sediments 0.063 26.80 

Undefined (natural) 0.0016 0.74 

Sub-total 0.0646 kg/yr 27.54 kg/yr 

WLA 

MOS 0.01 kg/yr 3.30 kg/yr 

Total TMDL 0.09 kg/yr 33.08 kg/yr 

Margin of Safety 

EPA has applied an explicit 10% margin of safety to the loading capacity for these 

TMDLs. The specific mass-based quantity for each pollutant with respect to each waterbody is 

included in Table 7-5. This margin of safety will provide additional protection for aquatic life, 

wildlife predators and human health. 

A number of assumptions were used in the derivation of each TMDL. Insufficient 

information is available to quantify the potential uncertainty associated with each of the 

assumptions used in the analysis. The parameters used in analysis were based on best available 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 66 

information and were selected to be conservative (i.e., most protective) where possible. The use 

of an explicit margin of safety and subsequent follow-up monitoring is intended to ensure that 

numeric targets are successfully achieved and that the adequacy of the load allocation is 

evaluated over time. Key areas of uncertainty recognized in the margin of safety include the 

following: 

• The loading capacity is calculated as a long-term annual average that results in meeting 

water quality standards (expressed as sediment, and tissue targets). Because the analysis 

is focused on long-term predictions, periodic fluctuations are not represented, and actual 

loading may differ in the short-term. 

• Long-term sediment deposition patterns were used to calculate the total amount of 

sediment deposited in each region. This long-term average value does not represent 

short-term or localized fluctuations in deposition rates. Periodic accumulation or 

scouring could be significant during large storm events. This could result in higher or 

lower deposition rates than the predicted sediment deposition and pollutant 

concentrations. 

• A constant suspended sediment concentration (300 mg/L) was used to calculate the 

loading capacity from San Diego Creek to water bodies downstream. In the short-term, 

sediment concentration will vary resulting in potentially higher or lower loadings to 

Rhine Channel. 

• A constant sediment porosity value was used to calculate loads associated with deposited 

sediment. Sediment porosity values used in the model to estimate loading capacity for 

San Diego Creek and Newport Bay (including Rhine Channel) (0.55) were slightly lower 

than those used for historical loads (0.65). No consolidation was assumed. This resulted 

in a conservative assumption, since consolidation would result in a lower porosity, which 

would increase the load associated with deposited sediment. 

Seasonal variation/Critical conditions 

These TMDLs rely on careful analysis of the full range of potential flow conditions to 

address seasonal variation and critical conditions in loads and flows. The sediment transport and 

deposition within each waterbody is driven by the velocity and sheer conditions of flow. The 

annual deposition is accounted for by using the sediment model developed by RMA (1997, 98, 

99) which incorporates various flow regimes throughout each year. The model represents 

various weather patterns and flow conditions for 25 years. 

As previously stated, freshwater flows from San Diego Creek and Santa Ana-Delhi 

Channel do not significantly transport sediments into Rhine Channel. The most important 

scenario may be the large flows associated with wet weather events, which may occur at any 

time of the year and produce extensive sediment redistribution and transportations downstream. 

This has yet to be verified in hydrologic modeling of chromium and mercury in Rhine Channel. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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VIII. Arsenic Analysis 

EPA has concluded that an arsenic TMDL is not required because available data indicate 

that applicable numeric water quality standards, and the best available screening guidelines used 

to interpret narrative standards, are not being exceeded. Although the State and EPA initially 

concluded that arsenic TMDLs were needed based on comparisons with older recommended 

screening values, we have revised our conclusions based on an updated data set and new 

information concerning arsenic toxicity and consumption risk. This section explains the basis for 

EPA’s revised assessment of the need for arsenic TMDLs. 

EPA’s initial assessment of fish tissue monitoring results was based on comparisons with 

two screening values. Total arsenic concentrations in fish tissue were compared to the California 

OEHHA screening value (1.0 mg/kg wet for total arsenic). This screening value was developed 

from a human health study for chemical contaminants in sportfish from two California 

freshwater lakes (OEHHA 1999). OEHHA recognized that inorganic arsenic is the preferred 

contaminant to evaluate for potential human health risk; however, analytical methods to measure 

inorganic arsenic were not available during that study. OEHHA developed a plan to a) evaluate 

total arsenic fish tissue results against the screening value for freshwater species and b) delay 

further decisions about water quality impairment or potential health risk until they had actually 

measured inorganic arsenic in popular sportfish (pers. commun. B. Brodberg). Furthermore, 

OEHHA recognizes its total arsenic screening value is ill-suited for saltwater systems. EPA 

Region 9 has reconsidered using this freshwater total arsenic tissue screening value and has 

determined that it would be inappropriate to make final decisions based only on comparison of 

total arsenic in tissues with this screening value. 

EPA’s initial assessment also considered another fish tissue screening value, (0.026 mg/kg 

wet for inorganic arsenic); however no monitoring data exists for measurements of inorganic 

arsenic in Newport Bay fish. To enable a comparison of available data to the inorganic arsenic 

screening value, EPA estimated levels of inorganic arsenic present in Newport Bay fish as a 

percentage of total arsenic for finfish (4% of total) and for shellfish (60% of total). These 

percentages were based on information obtained from a literature search (for finfish, Donohue 

and Abernathy 1999) or discussion with analytical chemists (for shellfish, pers. commun. J. 

Creed). Upon further review of the screening values cited in recent EPA guidance for assessing 

fish advisories (USEPA 2000d), EPA has determined the 0.026 mg/kg wet inorganic screening 

value is incorrect and that 1.2 mg/kg wet inorganic arsenic is a more reliable risk-based 

screening value. Preferably this screening value should be compared to measurements of 

inorganic arsenic in local fish, although calculation of inorganic arsenic as a percentage of total 

arsenic is still acceptable. 

In the process of developing these TMDLs, EPA reevaluated local fish tissue data in 

comparison with the new EPA screening value of 1.2 mg/kg wet inorganic arsenic based on 

EPA’s fish advisory guidance. The most recently available set of fish tissue monitoring results 

was compiled from Toxics Substances Monitoring program (1995-1998), California Fish 

Contamination Study (1999-2000) Southern California Coastal Water Research Project (2001b) 

and State Mussel Watch program (1995-2000). We evaluated results from both San Diego Creek 

and saltwater bodies of Newport Bay but focused more on saltwater results since those results 

showed some exceedances with respect to the OEHHA screening value applied in EPA’s earlier 

assessment. To be conservative and consistent with other agencies (e.g., FDA), EPA assumed 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 68 

that inorganic arsenic comprised 10% of total arsenic for finfish and 60% of total for shellfish. 

We used only one screening value, 1.2 mg/kg wet for inorganic arsenic, which is consistent with 

both State and Federal agencies’ determination that human health risk from arsenic exposure is 

attributed to inorganic arsenic exposures. 

The final assessment of saltwater tissue results (using calculated values of inorganic 

arsenic) shows no exceedances of the EPA inorganic screening value (1.2 mg/kg wet). This is 

true for both finfish (0%, n = 80) and shellfish (0%, n = 24). There are also no exceedances of 

freshwater tissue results. Table 8-1 summarizes arsenic tissue concentrations for Newport Bay. 

Table 8-2 provides a perspective of arsenic tissue concentrations for Newport Bay and other 

saltwater bodies. The raw data and calculated results for this reassessment are provided in 

Appendix B at the end of this summary document. Therefore, based on this revised assessment, 

EPA concludes that San Diego Creek and Newport Bay are not exceeding water quality 

standards for arsenic and that no TMDLs are needed. This result is consistent with local ambient 

water column data for arsenic, which indicate that Bay arsenic levels are about the same as 

average sea water arsenic levels. 

Table 8-1. Total Arsenic results in fish tissue in Newport Bay waterbodies (mg/kg wet) 

Waterbody Collection 

dates 

Org. n Min Max Mean Median 

San Diego 

Creek 

1995—‘98 TSMP 15 0.06 0.88 0.18 0.13 

1995—‘98 TSMP* 4 0.4 8.6 2.93 1.3 

1999—2000 CFCS 26 0.2 4.0 1.29 0.79 

Newport 

Bay 

(finfish) 2000-2001 SCCWRP 50 0.22 8.6 1.64 0.68 

(shellfish) 1995-2000 SMW 24 0.8 2.5 1.28 1.25 

*these TSMP results for individual samples, all other results are tissue composites 

Table 8-2. Total Arsenic results in marine waterbodies (mg/kg wet) 

Tissue Study n Range Mean Median 

Newport Bay 80 0.2 – 8.6 1.5 0.7 

Wash State 12 0.15 – 10.7 3.5 0.9 

Donohue 77 0.2 – 65 5.1 2.1 

Finfish 

Great Britain 720 0.9 – 30.1 5.6 4.3 

Newport Bay 24 0.8 – 2.5 1.3 1.3 

Wash State 10 1.0 – 6.9 2.4 2.2 

Shellfish 

Donohue 57 0.2 – 126 15.9 4.2 

Newport Bay results compiled from Table 8-1. 

Washington State results from Yilmazer et al. 2000 

Donohue (1996) 

Great Britain results from Collins et al. 1996 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

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IX. References

The list below may include some references cited only in the Technical Support Documents. 

Bay Protection Toxic Cleanup Program (BPTCP) 1997 Chemistry, Toxicity and Benthic Community Conditions in 

Sediments of Selected Southern California Bays and Estuaries SWRCB, EPA, NOAA, Calif. F&G, UC-Santa 

Cruz, Moss Landing Labs, Columbia Analytical Services, data collected in 1994 &1996. 

Bay, SM and D Lapota, J Anderson, J Armstrong, T Mikel, AW Jirik, S Asato. 2000 Southern California Bight 

1998 Monitoring Program: IV Sediment Toxicity. Southern California Coastal Water Research Project. 

Westminster, CA. 

Bruland, KW, JR Donat, and DA Hutchins 1991 Interactive influences of bioactive trace metals on biological 

production in oceanic waters. Limnol. Oceanogr. 36: 1555—1577. 

Buchman, MF 1999 NOAA Screening Quick Reference Tables, NOAA HAZMAT Report 99-1, Seattle, WA 

Coastal Protection and Restoration Division, National Oceanic and Atmospheric Admininstration, 12 pp. 

Buffle, J 1988 Complexation reactions in aquatic systems: an analytical approach. Chichester, Ellis Horwood. 

California Department of Food and Agriculture (CDFA) 1999 Red Imported Fire Ant. California Action Plan.

March. 

California Department of Fish and Game (CDFG) 2000a. Water Quality Criteria for Diazinon and Chlorpyrifos. 

CDFG. 2000b. Results of Chemical and Toxicological Analyses of Sediment and Chemical Analysis of Fish Tissue 

in Conjunction with the Red Imported Fire Ant (RIFA) Control Project. Memorandum to Santa Ana RWQCB. 

October 

California Department of Pesticide Regulation (CDPR) 2000 RIFA Insecticides and other Organophosphates: Use 

Pattern, Concentration, and Toxicity in Runoff Water, Source Identification, and Mitigation Measures. 

September. 

CDPR 1999 Annual Pesticide Use Data; User Documentation. July. 

California Division of Mines and Geology. 1976 Environmental Geology of Orange County, CA. Open-file report 

79-8. pp. 244-45. 

Camp Dresser & Mckee, Inc. 1985 Shallow Groundwater Investigation West Central Part of the Irvine Subbasin, a 

report submitted to The Irvine Company. 

Canadian Council of Ministers of the Environment. 1999 Canadian Sediment Quality Guidelines for the Protection 

of Aquatic Life: Summary Tables. In: Canadian Environmental Quality Guidelines, 1999, Canadian Council of 

Minister of the Environment, Winnipeg. 

Chadwick, DB, I Rivera-Duarte, T Hampton, B Davidson and E Crecelius. 2001 Contaminant Fluxes From 

Sediments – Risk Or Recovery? , International Conference on Remediation of Contaminated Sediments, 

October 10-12, 2001, Venice, Italy. 

City of Newport Beach . 1999 Final Sampling and Analysis Plan for Newport Harbor Sediment Characterization, 

Newport Beach, California, Ogden Environmental and Energy Services, Inc. 

Coastal Sport Fish Contamination Study, unpublished data. 2001 State Water Resource Board and OEHHA 

database. R.K. Brodberg, Office of Environmental Health Hazard Assessment, Calif. EPA, Sacramento, Calif. 

Collings, SE; MS Johnson and RT Leah. 1996 Metal contamination of Angler-caught fish from the Mersey Estuary. 

Mar. Envir. Res. 41: 281-297. 

Cooper, A. 1996 Diazinon in Urban Areas. Prepared for the Palo Alto Regional Water Quality Control Plant. 

August. 

Creed, J. 2001 pers. comm., EPA Cincinnati Office of Water research labs 

Cutter, GA 1991 Trace element in estuarine and coastal waters: United States studies from 1986-1990. Rev. 

Geophys. 29: 639-644. 

Donat, JR; K Lao and KW Bruland 1994 Speciation of copper and nickel in South San Francisco Bay: a multimethod approach. Anal. Chim. Acta 284: 547-572. 

Donohue, JM and CO Abernathy 1996 Exposure to Inorganic Arsenic (As) from Fish and Shellfish. Proceedings of 

International Arsenic conf. 

Duce RA, Hoffman GL, Ray BJ and PR Walsh 1976 Trace Metal Concentration as a Function of Particle Size in 

Marine Aerosols from Bermuda". Geophys. Res. Let. 3(6): 339-341. 

Eisler, R. 1994 A review of arsenic hazards to plants and animals with emphasis on fishery and wildlife resources. 

In: Arsenic in the Environment. Part II Human Health and Ecosystem effects. JO Nriagu, Ed. John Wiley & 

Sons, Inc. NY. pp185—251. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 70 

Enberg, RA et al. 1998 Federal and State Perspectives on Regulation and Remediation of Irrigation-Induced 

Selenium Problems, in Selenium in the Environment, Ed. by W T Frankenberger Jr. and S Benson, Marcel 

Dekker, Inc. New York, pp. 1-25. 

EXTOXNET. 1995-1996 Pesticide Information Profiles. http://ace.orst.edu/info/extoxnet/pips/ghindex.html 

Fowler, SW, and G. Benayoun 1976 Influence of Environmental Factors on Selenium Flux in Two Marine 

Invertebrates, Mar. Biol. (37): 59. 

Francesconi, KA and JS Edmonds 1994 Biotransformations of Arsenic in the Marine Environment. in Arsenic in 

the Environment, Part 1: Cycling and Characterization. J.O. Nriagu, editor. pp. 221-262. 

Geiszinger, AE; W Goessler and KA Francesconi. 2002 The marine polychaete Arenicola marina: its unusual 

arsenic compound pattern and its uptake of arsenate from seawater. Mar. Env. Res. 53, 37-50. 

Giesy JP, Solomon KR, Coats JR, Dixon K, Giddings J, and EE Kenaga. 1998 Ecological Risk Assessment of 

Chlorpyrifos in North American Aquatic Environments: Report of an Expert Panel. Dow AgroSciences LLC 

Study ID: GH-C 4660. 

Hall. L and R Anderson 2000 A Site-specific probabilistic Ecological Risk Assessment for Diazinon in California’s 

Newport Bay Watershed. September. 

Henderson, J. D. et al. 1995 Assessing Selenium Contamination in two San Joaquin Valley, CA, Sloughs, US Fish 

and Wildlife Service, Region 1, Division of Environmental Contaminants, Sacramento, CA. 

Hibbs, BJ and MM Lee. 2000 Sources of Selenium in the San Diego Creek Watershed. 

Kozelka, PB and KW Bruland 1998 Chemical Speciation of dissolved Cu, Zn, Cd and Pb in Narragansett Bay, 

Rhode Island. Mar. Chem. 60: 267—282. 

IRWD 1999 Irvine Ranch Water District Wetland Water Supply Project Monitoring Data Base 1997—99. Irvine 

Ranch Water District. Irvine, California. 

Lee, GF and S Taylor 2001a Results of Aquatic Toxicity Testing Conducted During 1999-2000 in the Upper 

Newport Bay Watersheds. USEPA 319(h) project report. May. 

Lee, GF and S Taylor 2001b Results of Aquatic Life Toxicity Studies Conducted During 1997-1999 in the Upper 

Newport Bay Watershed and Review of Existing Water Quality Characteristics of Upper Newport Bay and its 

Watershed. USEPA 205(j) project report. 

Lemly, AD 1993 Guidelines for Evaluating Selenium Data from Aquatic Monitoring and Assessment Studies, 

Environmental Monitoring and Assessment, 28, pp. 83-100. 

Lemly, AD 1995 A Position Paper on Selenium in Ecotoxicology: A Procedure for Deriving Site-Specific Water 

Quality Criteria, Ecotoxicology and Environmental Safety, 39, pp. 1-9. 

Long, ER, LJ Field and DD MacDonald 1998 Predicting Toxicity in Marine Sediments with Numerical Sediment 

Quality Guidelines, Environ. Toxicol. Chem. 17:4, pp. 714-727. 

Luoma, S. et al. 1992 Determination of Selenium Bioavailability to a Benthic Bivalve from Particulate and Solute 

Pathways, Environ. Sci. Technol. 26, pp. 485-491. 

Luoma, SN and TS Presser. 2000 Forecasting Selenium Discharges to the San Francisco Bay-Delta Estuary: 

Ecological Effects of a Proposed San Luis Drain Extension, USGS report 00-416. 

MacDonald, DD; RS Carr, FD Calder; ER Long and CG Ingersoll 1996 Development and evaluation of sediment 

quality guidelines for Florida coastal waters, Ecotoxicology, 5: 253-278. 

Maider, KJ et al. 1993 Comparative Toxicity of Selenate, Selenite, Seleno-DL-methionine, and Seleno-DLcysteine to Daphia Magna: Environ. Toxicol. Chem. (12): 755-763. 

Masters, P and D Inman 2000 Tranport and Fate of Organochlorines Discharged to the Salt Marsh at Upper 

Newport Bay, California, USA. Environ. Toxicol. Chem. 19:8 2076-84. 

Mosher BW and RA Duce 1989 The Atmosphere, in Occurrence and Distribution of Selenium, Ed. by Milan Ihnat, 

CRC Press, Inc. Florida, pp. 309. 

Mosher BW and RA Duce 1983 Vapor Phase and Particulate Selenium in the Marine Atmosphere. J. Geophys. 

Res. 88: 6761-6676. 

Muller, FLL 1996 Interactions of copper, lead and cadmium with the dissolved, colloidal and particulate 

components of estuarine and coastal waters. Mar. Chem 52: 245-68. 

National Academy of Sciences 1973 Water Quality Criteria (Blue Book). EPA-R3-73-033. USEPA Ecological 

Research Series. 

Neff, JM 1997 Ecotoxicology of arsenic in the marine environment. Environ. Tox. Chem., 17(4): pp. 917-927. 

New York Department of Environmental Conservation 1994 Niagra River biota contamination project - fish flesh 

criteria for piscivorous wildlife. NYDEC, Division of Fish and Wildlife, Bureau of Environemtnal Protection 

Technical Report 87-3, 182p. 

New York Department of Environmental Conservation 1998 Technical guidance for screening contaminated 

sediments (for wildlife bioaccumulation). Albany, NY, Div. of Fish and Wildlife, Div. of Marine Resources. 

36pp. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 71 

Novartis Crop Protection Inc. 1997 An Ecological Risk Assessment of Diazinon in the Sacramento and San Joaquin 

River Basins. Technical Report 11-97. 

Nriagu, JO. 1989 Global Cycling of Selenium, in Occurrence and Distribution of Selenium, ed. M. Ihnat, CRC 

Press, Inc. Florida, pp. 327-340. 

OCPFRD 2000 Orange County NPDES Stormwater Program, Annual Progress Report. Data from 1996 to June 

2000. Orange County Public Facilities and Resources Department, Santa Ana, California. 

OCPFRD 1999 Peters Canyon Wash/San Diego Creek Nutrient Study. 

OEHHA 1999 Prevalence of Selected Target Chemical Contaminants in Sport Fish from Two Californa Lakes: 

Public Health Designed Screening Study. June 1999, RK Brodberg and GA Pollack, Pesticide and Environ. 

Toxic. Sctn, Office of Environmental Health Hazard Assessment, Calif. EPA, Sacramento, Calif. 

Ogden Environmental and Energy Services. 2000 Final Sampling and Analysis Plan for Newport Harbor Sediment 

Characterization. 

Orange County Coastkeeper 1999 Rhine Channel Sediment Metal Characterization. Report prepared by MBC 

Applied Environmental Services, Costa Mesa, Calif. 

Presser TS 1994 Geologic Origin and Pathways of Selenium from the California Coast Ranges to the West-Central 

San Joaquin Valley, in Selenium in the Environment, Ed. by WT Frankenberger, Jr. and S. Benson, Marcel 

Dekker, Inc. New York, pp. 139-155. 

Resource Management Associates (RMA) 2001 Newport Bay Water Quality Model Development—3-D Stratified 

Flow Analysis. prepared for California Regional Water Quality Control Board, Santa Ana Region, February. 

RMA 1999 Upper Newport Bay Feasibility Report—Alternative Analysis. prepared for US Army Corps of 

Engineers. 

RMA 1998 Upper Newport Bay Feasibility Report—Numerical model development and baseline conditional 

analysis. (for US Army Corps of Engineers). 

RMA 1997 Upper Newport Bay Feasibility Report—Final model and GUI development and implementation 

report. (for US Army Corps of Engineers). 

San Diego Regional Water Quality Control Board 2001 Draft Dissolved Copper TMDL for Shelter Island Yacht 

Basin. California Regional Water Quality Control Board, San Diego California. 

Santa Ana Regional Water Quality Control Board (RWQCB) 2001a Draft TMDL for OP Pesticides in San Diego 

Creek and Newport Bay. Staff report, California Regional Water Quality Control Board, Santa Ana Region, 

Riverside, California. 

Santa Ana RWQCB 2001b Draft TMDL for Selenium in San Diego Creek and Newport Bay. Staff report, 

California Regional Water Quality Control Board, Santa Ana Region, Riverside, California. 

Santa Ana RWQCB 2000 Final Problem Statement for the Total Maximum Daily Load for Toxic Substances in 

Newport Bay and San Diego Creek. Staff report, California Regional Water Quality Control Board, Santa Ana 

Region, Riverside, California. 

Santa Ana RWQCB 1998 Water Quality Assessment and Clean Water Act Section 303(d) List. California Regional 

Water Quality Control Board, Santa Ana Region, California Environmental Protection Agency, Riverside, 

California. 

Santa Ana RWQCB 1995 Water Quality Control Plan for the Santa Ana River Basin California Regional Water 

Quality Control Board, Santa Ana Region, California Environmental Protection Agency, Riverside, California. 

Scanlin, J and A Cooper 1997 Outdoor Use Characterization of Diazinon and other Pesticides in Alameda County. 

Prepared for the Alameda County Flood Control and Water Conservation District. September. 

Scanlin, J and A Feng 1997 Characterization of the Presence and Sources of Diazinon in the Castro Valley Creek 

Watershed. Prepared for the Alameda Countywide Clean Water Program and the Alameda County Flood 

Control and Water Conservation District. June. 

Schiff, K and L Tiefenthaler 2000 Anthropogenic versus natural mass emission from an urban watershed. 

SCCWRP Annual report. pp. 63-70. 

Schoof, RA, LJ Yost, J Eickhoff, EA Crecilius, DW Cragin, DM Meacher, and DB Menzel 1999 A Market Basket 

Survey of Inorganic Arsenic in Food. Food and Chem. Toxic. 37: 839—846. 

Seiler, RL et al. 1999 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the 

Western United States: US Geological Survey Circular 1180, pp. 36. 

Skorupa, JP 1998 Selenium Poisoning of Fish and Wildlife in Nature: Lessons from Twelve Real-World Examples, 

in Environmental Chemistry of Selenium, WT Frankenberger Jr. and RA Engberg, editors, Marcel Dekker, Inc. 

SMW 2000 State Mussel Watch Program 1983-00 Data Base and 1995-97 Data Report. State Water Resources 

Control Board, California Environmental Protection Agency, Sacramento, California 

Southern California Coastal Water Research Project (SCCWRP) 2001a Newport Bay Sediment Toxicity Study—

Progress Report.(for contract with Santa Ana RWQCB, dated Oct. 23, 2001.) Southern California Coastal 

Water Research Program. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 72 

SCCWRP 2001b Newport Bay Fish Bioaccumulation Study—Progress Report.(for contract with Santa Ana 

RWQCB, dated Oct. 4, 2001.) Southern California Coastal Water Research Program. 

SCCWRP, unpublished data 1998 Sediment Chemistry from Southern California Bight including offshore Harbors 

and estuaries. Southern California Coastal Water Research Program. 

Stoecker, DK, WG Sunda and LH Davis 1986 Effects of copper and zinc on two planktonic ciliates. Mar. Biol. 

92: 21-29. 

Stolzenbach, KD; R Lu; C Xiong; S Friedlander; R Turco; K Schiff; and L Tiefenthaler 2001 Measuring and 

Modeling of Atmospheric Deposition on Santa Monica Bay and the Santa Monica Bay Watershed. Final Report 

to Santa Monica Restoration Project. 41pp. 

Sunda, WG; PA Tester and SA Huntsman 1987 Effects of cupric and zinc ion activities on the survival and 

reproduction of marine copepods. Mar. Biol. 94: 203-210. 

TDC Environmental 2001 Diazinon and Chlorpyrifos Products: Screening for Water Quality Implications 

Thomann, R and J Mueller 1987 Principles of Surface Water Quality Modeling and Control. Harper Collins Pub. 

Tokunaga, TK et al. 1994 Field Investigations of Selenium Speciation, Transformation, and Transport in Soils 

from Kesterson Reservoir and Lahontan Valley, in Selenium in the Environment, WT Frankenberger and S 

Benson, editors, Marcel Dekker, Inc. Yew York, pp. 119-138. 

TOXSCAN, Inc. 1995 Chemical Analysis and Toxicity Evaluation of Sediment Proposed for Dredging and Ocean 

Disposal: Unit I Sediment Basin and Access Channel. 

Trimble, SW 1987 Field Research Report for San Diego Creek Channel Study, Summer 1987. Univ. of California 

at Los Angeles, Los Angeles, California 

Tsai, P; E Hansen; K Lee; D Yee; D Tucker and R Hoenicke 2001 Atmospheric Deposition of Trace Metals in the 

San Francisco Bay area. abstract for WEFTEC conf. Atlanta, GA 

TSMP 1987-99 Toxic Substance Monitoring Program 1987-99 Data Base. State Water Resources Control Board, 

California Environmental Protection Agency, Sacramento, California 

US Army Corp of Engineers (ACOE) 2000 Upper Newport Bay Ecosystem Restoration Feasibility Study: 

Environment Impact Statement/Report. Final Report, September. 

US Fish & Wildlife Service 2001 Environmental Contaminant Encyclopedia. www.nature.nps.gov/toxic/ National 

Park Service website. US Department of Interior report. 

US Fish & Wildlife Service 2000 Biological Opinion on EPA’s “Water Quality Standards: Establishment of 

Numeric Criteria for Priority Toxic Pollutants or the State of California”. 

US Fish & Wildlife Service 1998 Guidelines for Interpretation of the Biological Effect of Selected Constituents in 

Biota, Water, and Sediment. US Department of Interior report. 

US Geological Survey 2000 Stormflow Chemistry in the Santa Ana River below Prado Dam and at the Diversion 

Downstream from Imperial Highway, Southern California, 1995-98. 

USEPA 2001a Update of Ambient Water Quality Criteria for Cadmium. EPA-822-R-01-001. U.S. Environmental 

Protection Agency, Office of Water, Wash. DC. Notice of availability April 12, 2001 

USEPA 2001b Diazinon Revised Risk Assessment and Agreement with Registrants. 

USEPA 2000a California Toxics Rule [CTR], Water Quality Standards; Establishment of Numeric Criteria for 

Priority Toxic Pollutants for the State of California; Federal Register Rule—40CFR Part 131. U.S. 

Environmental Protection Agency, Washington, D.C. 

USEPA 2000b Chlorpyrifos Revised Risk Assessment and Agreement with Registrants. 

USEPA 2000c Ambient Aquatic Life Water Quality Criteria: Diazinon (Draft). 

USEPA 2000d Guidance for Assessing Chemical Contaminant Data for Use in Fish Consumption Advisories, Vol. 

1: Fish Sampling and Analysis, 3rd ed. EPA-823-B-00-007. U.S. Environmental Protection Agency, Office of 

Water, Wash. DC. 

USEPA 2000e Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. 

EPA-822-B-00-004. U.S. Environmental Protection Agency, Office of Water, Wash. DC. 

USEPA 1999a Environmental Risk Assessment for Diazinon. 

USEPA 1999b Pesticides Industry Sales and Usage. 1996 and 1997 Market Estimates. EPA-733-R-99-001. U.S. 

Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Wash. DC. 

USEPA 1991 Guidance for Water Quality-based Decisions: The TMDL Process. EPA-440/4-91-001. Office of 

Water, Washington, DC. 

USEPA 1997 National Toxics Rule [NTR], Water Quality Standards; Establishment of Numeric Criteria for 

Priority Toxic Pollutants for the State of California; Federal Register Rule—40CFR Part 131. U.S. 

Environmental Protection Agency, Washington, D.C. 

USEPA 1986 Ambient Aquatic Life Water Quality Criteria: Chlorpyrifos. EPA-440/5-005-86-001. Office of 

Water, Washington, DC. USEPA Region 9 2000 Guidance for Developing TMDLs in California. 

USEPA Region 9 2001 Decision Document for Assessment of San Diego Creek and Newport Bay Water Quality 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 73 

USEPA Region 9 2000 Guidance for Developing TMDLs in California. 

http://www.epa.gov/region09/water/tmdl/index.html 

Waldner, L. 2001 pers. comm. Orange County Public Facilities Resource Division 

Wang, WX et al. 1996 Kinetic Determinations of Trace Element Bioaccumulation in the Mussel Mytilus edulis: 

Mar. Ecol. Prog. Ser. 140: 91-113. 

Weis, P; JS Weis and LM Coohill 1991 Toxicity of estuarine organisms of leachates from chromated copper 

arsenate treated wood. Arch. Environ. Contam. Toxicol. 20: 118-124. 

White AF, Benson SM, Yee AW, Wollenberg HA and S Flexser 1991 Groundwater Contamination at the 

Kesterson Reservoir, California. 2. Geochemical Parameters Influencing Selenium Mobility Wat. Resour. Res. 

27(6): 1085-1098. 

Wiemeyer, SN; DR Clark, JW Spann, and AA Belisle 2001 Dicofol Residues in Eggs and Carcasses of Captive 

American Kestrels. Environ. Toxicol. Chem. 20(12): 2848-2851. 

Wilber, CG. 1980 Toxicology of Selenium: A Review, Clin. Toxicol. 17: 171. 

Wilen, C. 2001 Residential Pesticide Use and Attitude Survey, San Diego Creek Watershed of Orange County, 

California. Report for California Department of Pesticide Regulation. University of California Statewide 

Integrated Pest Management Program. 

Wisconsin Department of Natural Resources 1997 Polychlorinated Biphenyl (PCB) Contaminated Sediment in the 

Low Fox River. PUBL-WT-482-97. 

Yilmazer, M and S Shawky, RN Sanga, RM Lorenzana 2001 Concurrent Exposure Evaluations Arsenic MCL 

Options and Arsenic in seafood. Toxicol. Sci. 60(1): p90. 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 74 

X. Glossary and abbreviations 

205(j) Section 205, part j of Clean Water Act, addresses water monitoring grants 

319(h) Section 319, part h of Clean Water Act, addresses non-point source pollution 

ACOE Army Corps of Engineers 

ai active ingredient 

ambient existing environmental conditions (or concentrations) 

BAF Bioaccumulation factor 

BCF Bioconcentration factor 

BSAF Biota-sediment accumulation factor 

bgs Below ground surface, relates to monitoring wells 

Bight ‘98 Southern California Bight (coastal waters) study 

BMP best management practice 

BPTCP Bay Protection and Toxic Cleanup Program 

CCC criterion continuous concentration = chronic 

CDFG (California) Department of Fish and Game 

cfs Cubic feet per second, pertains to stream flow rates 

CFCS California Fish Contamination Study (OEHHA) 

CMC criterion maximum concentration = acute 

CTR California Toxics Rule 

cv coefficient of variation 

CWA Clean Water Act 

DO dissolved oxygen 

DPR (California) Department of Pesticide Regulation 

DTSC (California) Dept. of Toxic Substances Control 

ELISA Enzyme Linked Immunosorbant Assay 

EPA U.S. Environmental Protection Agency 

ERL Effects Range-Low, sediment quality guideline for low impact 

ERM Effects Range-Median, NOAA sediment quality guideline for median negative impact 

FIFRA Federal Insecticide, Fungicide and Rodenticide Act 

flip Fraction (of organic compound associated) with lipid 

foc Fraction (of organic compound associated) with octanol 

GC Gas chromatograph 

GC/MS Gas chromatography/mass spectrometry 

HPLC/MS high performance liquid chromatography/mass spectrometry 

IPM Integrated Pest Management, part of UC-Cooperative Extension 

IRWD Irvine Ranch Water District 

LA Load allocation for non-point sources (including background) 

MLLW mean low low water 

MOS Margin of safety 

NAWQA National Water Quality Assessment Program 

ng/L Nanograms per liter (= parts per trillion) 

NOAA National Oceanic Atmospheric Administration 

NPDES National Pollutant Discharge Elimination System 

NY DEC New York Dept. of Environmental Conservation 

OC Organochlorine compound; e.g., chlordane, dieldrin, DDT, PCB, toxaphene 

OCHCA Orange County Health Care Agency 

OCPFRD Orange County Public Facilities and Resources Department 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 75 

OEHHA Office of Environmental Health Hazard Assessment 

OP Organophosphate, type of pesticide 

OPP Office of Pesticide Programs 

PCB polychlorinated biphenyl 

PCH Pacific Coast Highway 

PCW Peters Canyon Wash, a tributary of San Diego Creek 

PEL Probable Effects Level, sediment quality guideline for Florida Dept. of Env. Protection 

PERA probabilistic ecological risk assessment 

POTW Publicly owned treatment works 

ppb Part per billion = ug/L (for solution concentration) or ng/g (for dry soil conc.) 

ppm Part per million = mg/L (for solution concentration) or ug/g (for dry soil conc.) 

PPT parts per thousand (salinity) 

Porewater (interstitial) water contained in sediments 

RMA Resource Management Associates, developed hydrologic models for US Army Corp of Eng. 

SA RWQCB Santa Ana Regional Water Quality Control Board 

SD RWQCB Santa Diego Regional Water Quality Control Board 

SAD Santa Ana-Delhi Channel 

SCCWRP Southern California Coastal Water Research Program 

SDC San Diego Creek 

se standard error [as used in table column headings] 

SMW State Mussel Watch 

SWRCB State Water Resources Control Board 

TAC Technical Advisory Committee 

TEL Threshold Effects Level, sediment quality guideline (for Florida Dept. of Env. Protection) 

TIE toxicity investigation evaluation = study to identify and characterize chemicals causing toxicity 

TMDL total maximum daily load 

TOC total organic carbon 

TSMP Toxic Substances Monitoring Program (State Water Board) 

TUa acute toxic units 

UCD University of California, Davis 

ug/L micrograms per liter (= parts per billion) 

US FWS United States Fish & Wildlife Service 

USGS United States Geological Survey 

WDR Waste discharge report, 

WLA Wasteload allocation for point sources (including general stormwater permit) 

WYL San Diego Creek at Culver sampling site 

xe mean error [as used in table column headings] 

 

 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 76 

Appendix A 

Designated beneficial uses for Newport Bay and San Diego Creek watershed. 

Water Body M

U

N 

A

G

R 

I

N

D 

P

R

O

C 

G

W

R

N

A

V 

P

O

W

R

E

C

1 

R

E

C

2 

C

O

M

M

W

A

R

M 

C

O

L

D 

B

I

O

L 

W

I

L

D 

R

A

R

E

S

P

W

N 

M

A

R 

S

H

E

L 

E

S

T 

Lower NB + x x x x x x x x x 

Upper NB + x x x x x x x x x x 

San Diego 

Creek Reach 1 

+ x x x x 

San Diego 

Creek Reach 2 

+ I I I I 

Tributaries of 

San Diego 

Creek 

+ I I I I 

x present or potential beneficial use 

I intermittent beneficial use 

+ excepted from MUN 

MUN = municipal and domestic supply 

AGR = agricultural supply 

IND = industrial service supply 

PROC = industrial process supply 

GWR = groundwater recharge 

NAV = navigation 

POW = hydropower generation 

REC1 = water contact recreation 

REC2 = non-contact water recreation 

COMM = commercial and sport fishing 

WARM = warm freshwater habitat 

COLD = cold freshwater habitat 

BIOL = preservation of biological habitats 

WILD = wildlife habitat 

RARE = rare, threatened, or endangered species 

SPWN = spawning, reproduction, and/or early development 

MAR = marine habitat 

SHEL = shellfish harvesting 

EST = estuarine habitat 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 77 

Appendix B 

Arsenic Fish Tissue Monitoring data 

 SPECIES NAME Date Total 

Arsenic 

 Inorganic 

Arsenic 

 Screening Value 

(mg/kg wet) 

 OEHHA = 1.0 EPA = 1.2 

 #/samp. (4% Tot. As) (10% Tot. 

As) 

OEHHA data ' 00 

Newport Beach Barred Surfperch 6/00/2000 10 0.601 0.024 0.060 

Newport Beach Shiner Surfperch 06/00/2000 10 1.130 0.045 0.113 

Newport Beach White Croaker 06/00/2000 5 0.778 0.031 0.078 

Newport Beach Pier Barred Surfperch 06/00/2000 10 0.577 0.023 0.058 

Newport Beach Pier White Croaker 06/00/2000 5 0.668 0.027 0.067 

Balboa Pier Barred Surfperch 06/00/2000 3 0.911 0.036 0.091 

Balboa Pier Diamond Turbot 06/00/2000 4 3.094 0.124 0.309 

Newport Jetty Black Surfperch 06/00/2000 5 0.774 0.031 0.077 

Newport Jetty Shiner Surfperch 06/00/2000 10 0.906 0.036 0.091 

Newport Jetty Spotted Turbot 06/00/2000 5 3.673 0.147 0.367 

Newport Bay/above 

PCH Br 

Shiner Surfperch 06/00/2000 10 0.969 0.039 0.097 

Newport Bay/above 

PCH Br 

Spotted Turbot 06/00/2000 5 1.775 0.071 0.177 

Newport Bay/above 

PCH Br 

Yellowfin Croaker 06/00/2000 4 0.585 0.023 0.059 

Newport Beach Barred Surfperch 8/4/99 5 0.811 0.032 0.081 

Newport Beach California Corbina 8/4/99 5 0.449 0.018 0.045 

Newport Beach Walleye Surfperch 6/22/99 3 0.618 0.025 0.062 

Newport Pier Barred Surfperch 8/4/99 5 1.06 0.042 0.106 

Newport Pier California Corbina 8/4/99 5 0.411 0.016 0.041 

Newport Pier Spotted Turbot 6/16/99 3 2.69 0.108 0.269 

Newport Pier Yellowfin Croaker 8/4/99 3 0.529 0.021 0.053 

Balboa Pier Diamond Turbot 6/15/99 5 4 0.160 0.400 

Balboa Pier Walleye Surfperch 6/9/99 5 0.587 0.023 0.059 

Newport Jetty Spotted Scorpionfish 5/19/99 5 0.202 0.008 0.020 

Newport Jetty Spotted Turbot 5/19/99 5 3.12 0.125 0.312 

Newport Bay Diamond Turbot 5/19/99 5 1.88 0.075 0.188 

Newport Bay Shiner Surfperch 5/27/99 5 0.672 0.027 0.067 

 

SCCWRP Winter '01 

barred sand bass Outer Lower 1 1 0.65 0.026 0.065 

black perch Outer Upper 1 2 0.53 0.021 0.053 

black perch Outer Lower 1 3 0.96 0.038 0.096 

black perch Outer Lower 2 4 0.86 0.034 0.086 

black perch Outer Lower 3 5 0.69 0.028 0.069 

California halibut Outer Upper 1 6 0.58 0.023 0.058 

California halibut Outer Upper 2 7 0.85 0.034 0.085 

California halibut Outer Upper 3 8 0.47 0.019 0.047 

California halibut Outer Lower 1 9 0.91 0.036 0.091 

California halibut Outer Lower 2 10 0.41 0.016 0.041 

C-O sole Outer Lower 1 11 5.74 0.230 0.574 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 78 

C-O sole Outer Lower 2 12 5.01 0.200 0.501 

diamond turbot Outer Upper 1 13 1.82 0.073 0.182 

diamond turbot Outer Upper 2 14 3.89 0.156 0.389 

diamond turbot Outer Upper 3 15 2.85 0.114 0.285 

diamond turbot Outer Lower 1 16 4.20 0.168 0.420 

diamond turbot Outer Lower 2 17 3.45 0.138 0.345 

fantail sole Outer Lower 1 18 0.97 0.039 0.097 

shiner perch Outer Upper 1 19 0.67 0.027 0.067 

spotted sand bass Outer Upper 1 20 0.47 0.019 0.047 

spotted sand bass Outer Lower 1 21 0.63 0.025 0.063 

spotted turbot Outer Upper 1 22 3.92 0.157 0.392 

spotted turbot Outer Lower 1 23 7.28 0.291 0.728 

spotted turbot Outer Lower 2 24 8.57 0.343 0.857 

spotted turbot Outer Lower 3 25 5.53 0.221 0.553 

SUMMER 2001 

barred sand bass Outer Lower 1 13 0.44 0.018 0.044 

black perch Outer Lower 1 10 0.50 0.020 0.050 

black perch Outer Lower 2 11 0.40 0.016 0.040 

black perch Outer Lower 3 12 0.58 0.023 0.058 

California corbina Outer Lower 1 17 1.24 0.050 0.124 

California corbina Outer Lower 2 18 1.15 0.046 0.115 

California corbina Outer Lower 3 19 1.57 0.063 0.157 

California halibut Outer Lower 1 25 0.52 0.021 0.052 

diamond turbot Outer Upper 1 20 2.52 0.101 0.252 

diamond turbot Outer Upper 2 21 2.89 0.116 0.289 

diamond turbot Outer Lower 1 22 2.12 0.085 0.212 

jacksmelt Outer Upper 1 1 0.51 0.020 0.051 

jacksmelt Outer Upper 2 2 0.53 0.021 0.053 

jacksmelt Outer Upper 3 3 0.58 0.023 0.058 

kelp bass Outer Lower 1 4 0.49 0.020 0.049 

spotfin croaker Outer Lower 1 23 0.68 0.027 0.068 

spotfin croaker Outer Lower 2 24 0.93 0.037 0.093 

spotted sand bass Outer Lower 1 14 0.22 0.009 0.022 

spotted sand bass Outer Lower 2 15 0.24 0.010 0.024 

spotted sand bass Outer Lower 3 16 0.25 0.010 0.025 

yellowfin croaker Outer Lower 1 5 0.36 0.014 0.036 

yellowfin croaker Outer Lower 2 6 0.34 0.014 0.034 

yellowfin croaker Outer Lower 3 7 0.47 0.019 0.047 

yellowfin croaker Inner Lower 1 8 0.49 0.020 0.049 

yellowfin croaker Inner Lower 2 9 0.27 0.011 0.027 

TSMP data '95--'98 

Upper NB/Dunes Brown Sm. Shark (F) 6/10/98 1 8.620 0.345 0.862 

Upper NB/Dunes Diamond Turbot (F) 6/20/97 1.480 0.059 0.148 

NB/Rhine Channel Chub Mackerel (F) 7/11/97 0.427 0.017 0.043 

NB/Rhine Channel Black Croaker (F) 6/18/95 1.200 0.048 0.120 

(Data is for Individual Filet Samples) 

saltwater finfish results 

count 80 

max 8.62 0.34 0.86 

 mean 1.59 0.06 0.08 

median 0.78 0.03 0.08 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 79 

 Tot. As 

Inorg. As 

State Mussel Watch mussels 

Upper Newport Bay (60% of As Total) 

UNB/Mariner's Drive TCM 1/27/97 1.10 0.018 

UNB/Mariner's Drive TCM 3/24/98 1.70 0.028 

UNB/Mariner's Drive TCM NA 

UNB/Mariner's Drive TCM 2/2/00 0.90 0.015 

UNB/ PCH Bridge TCM 1/30/95 NA 

UNB/ PCH Bridge TCM 1/17/96 1.40 0.023 

UNB/ PCH Bridge NA NA 

UNB/ PCH Bridge TCM 3/24/98 1.40 0.023 

UNB/ PCH Bridge TCM 3/29/99 1.40 0.023 

UNB/ PCH Bridge TCM 2/2/00 1.00 0.017 

 

Lower Newport Bay 

LNB/Turning Basin TCM 1/30/95 NA 

LNB/Turning Basin TCM 1/17/96 1.20 0.020 

LNB/Turning Basin na NA 

LNB/Turning Basin RBM 3/24/98 0.80 0.013 

LNB/Turning Basin TCM 3/29/99 1.30 0.022 

LNB/Turning Basin TCM 2/2/00 1.00 0.017 

LNB/Police Docks RBM 3/24/98 1.10 0.018 

LNB/Entrance TCM 3/29/99 2.50 0.042 

Rhine Channel 

Rhine Ch./Crows Nest TCM 1/30/95 NA 

Rhine Ch./Crows Nest TCM 1/17/96 1.20 0.020 

Rhine Ch./Crows Nest TCM 1/27/97 1.20 0.020 

Rhine Ch./Crows Nest TCM 3/24/98 1.60 0.027 

Rhine Ch./Crows Nest TCM 3/29/99 1.50 0.025 

Rhine Ch./Crows Nest TCM 2/2/00 1.10 0.018 

Rhine Ch./End TCM 1/30/95 NA 

Rhine Ch./End TCM 1/17/96 1.30 0.022 

Rhine Ch./End TCM 1/27/97 1.30 0.022 

Rhine Ch./End TCM 3/24/98 1.40 0.023 

Rhine Ch./End TCM 3/29/99 1.30 0.022 

Rhine Ch./End TCM 2/2/00 0.90 0.015 

Rhine Ch./Upper TCM 2/2/00 1.00 0.017 

(Data is for Composite Mussel Samples) 

Saltwater shellfish results 

count 24 

 max 2.50 0.04 

 mean 1.28 0.02 

 median 1.25 0.02 
Newport Bay Toxic Pollutant TMDLs Public Review Draft 

 summary document 80 

 Tot. As 

Inorg. As 

TSMP data '96--'98 4% 10% 

San Diego Creek 

San Diego 

Creek/Michelson 

Red Shiner 6/9/98 0.344 0.014 0.034 

Peters Canyon 

Channel 

Red Shiner 6/9/98 0.116 0.005 0.012 

San Diego 

Creek/Barranca 

Red Shiner 6/9/98 0.200 0.008 0.020 

Delhi Channel Striped Mullet 6/9/98 0.882 0.035 0.088 

San Diego 

Creek/Michelson 

Red Shiner 6/19/97 0.134 0.005 0.013 

Peters Canyon 

Channel 

Red Shiner 6/19/97 0.057 0.002 0.006 

Peters Canyon 

Channel 

Red Shiner 6/19/97 0.063 0.003 0.006 

San Diego 

Creek/Barranca 

Red Shiner 6/19/97 0.148 0.006 0.015 

Delhi Channel Red Shiner 6/18/97 0.085 0.003 0.009 

San Diego 

Creek/Michelson 

Red Shiner 11/6/96 0.06 0.002 0.006 

San Diego 

Creek/Michelson 

Red Shiner 11/6/96 0.07 0.003 0.007 

Peters Canyon 

Channel 

Red Shiner 11/6/96 0.15 0.006 0.015 

San Diego 

Creek/Michelson 

Red Shiner 6/17/95 0.150 0.006 0.015 

San Diego 

Creek/Michelson 

Red Shiner 6/17/95 0.170 0.007 0.017 

Peters Canyon 

Channel 

Red Shiner 6/17/95 0.090 0.004 0.009 

Freshwater finfish results 

count 15 

 max 0.88 0.04 0.09 

 mean 0.18 0.01 0.02 

 median 0.13 0.01 0.01