Total Maximum Daily Loads 

For Toxic Pollutants 

San Diego Creek and Newport Bay, California 

U.S. Environmental Protection Agency 

Region 9 

Established June 14, 2002 

Alexis Strauss 

Director 

Water Division 

EPA Region 9 
 

Newport Bay Toxic Pollutant TMDLs 

Table of Contents 

Summary TMDL Document 

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

II. Overview of TMDLs and Available Data .......................................... 12
 

III. Organophosphate (OP) Pesticide TMDLs .......................................... 24
 

IV. Selenium TMDLs...................................................................... 32
 

V. Metals TMDLs........................................................................ 40
 

VI. Organchlorine Compound TMDLs................................................... 51
 

VII. Chromium and Mercury TMDLs .................................................... 63
 

VIII. Arsenic Analysis........................................................................ 69
 

IX. Implementation Recommendations................................................... 71
 

X. References.............................................................................. 77
 

XI. Glossary/Abbreviations................................................................ 82
 

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 

H. Decision Document 

I. Responsiveness Summary 

summary document 1 
 

Newport Bay Toxic Pollutant TMDLs 

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 

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Newport Bay Toxic Pollutant TMDLs 

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

supercede the TMDLs being established now by EPA. 

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 April 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 establishing the TMDLs for these toxic pollutants in order to meet the 

requirements of the decree. On April 12, 2002, EPA published a public notice seeking comment 

on the proposed toxic pollutant TMDLs for San Diego Creek and Newport Bay. EPA carefully 

considered comments received during the comment period and made some changes in the final 

TMDL decisions. EPA also completed a responsiveness summary that describes how EPA 

considered each comment received. 

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 by EPA 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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Newport Bay Toxic Pollutant TMDLs 

Table 1-1. Toxic Pollutants per waterbody requiring TMDL Development 

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 

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 (Decision Document 2002), 

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. The impacts of greatest potential concern in these water bodies are: a) 

chemical bioaccumulation through the aquatic food chain at levels which could harm human 

health when we consume fish or shellfish and b) chemical concentrations in water, sediment or 

biota that cause adverse effects in aquatic life or aquatic-dependent species. 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. 

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Newport Bay Toxic Pollutant TMDLs 

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 risk 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 TMDLs, 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. A summary of public 

comments and EPA’s responses to those comments is provided in another TSD. 

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Newport Bay Toxic Pollutant TMDLs 

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.) 

EPA does not establish implementation plans as part of TMDLs under currently 

applicable federal regulations. However, we have included several implementation 

recommendations (see Section IX) which are intended to assist the State and local stakeholders 

in devising appropriate pollutant control and monitoring plans to address these toxic pollutants. 

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. When NPDES permits for point source discharges addressed in the TMDLs are revised, 

their provisions must be consistent with the requirements and assumptions of any wasteload 

allocations contained in these TMDLs (see 40 CFR 122.44(d)(1)(vii)(B)). Permit modification 

may occur when the permits are reopened or reissued. 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 

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Newport Bay Toxic Pollutant TMDLs 

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 

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. 

Environmental Setting 

(see Figure 1-1 in TSD--Part A) 

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, Marshburn Channel, Agua Chinon Wash, Borrego 

Canyon Wash and Serrano Creek 

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

include the San Diego Creek, Santa Ana-Delhi Channel, Big Canyon Wash, Costa Mesa Channel 

and other local drainages. 

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. 

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Newport Bay Toxic Pollutant TMDLs 

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. In the past six years, San Diego 

Creek has a mean base flow rate of approximately 12 cubic feet per second (cfs) (for all flows 

<20 cfs). Storm events, depending on their magnitude, intensity, and antecedent conditions, can 

increase this daily mean flow to over 9000 cfs (Dec. 7, 1997). 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, 

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 

summary document 8 
 

Newport Bay Toxic Pollutant TMDLs 

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. As a result of these land use and drainage changes, surface and groundwater hydrology 

have been substantially altered from natural conditions. 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 pesticides and metals associated with human 

habitation (e.g., buildings, landscaping, and motor vehicles). In addition, land use activities 

which cause erosion may contribute to the delivery of pesticides and other pollutants that adhere 

to sediments or normally remain in solid form. 

summary document 9 
Newport Bay Toxic Pollutant TMDLs 

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 

Agricultural/ 5092 6.6 0 0 5147 5.2 

Residential 11,668 5285 19420 19.7 15.2 18.2 

Commercial 6381 8.3 2397 8.3 9641 9.8 

Industrial 3965 5.2 1102 3.8 5263 5.4 

Education/Religion/ 15,811 20.6 825 2.8 17,393 17.7 

Recreation 

Roads 10,295 13.4 3446 11.9 15,774 16.0 

Transportation 1177 1.5 99 0.3 1326 1.3 

No assigned land 440 0.6 339 1.1 936 0.9 

code 

Vacant 21,910 28.5 1060 3.7 23,462 23.9 

Total 76,739 99.9 29003 100 98,362 99.9 

Source: OCPFRD land use data defined by sub-watersheds to compose each watershed. (see TSD Part A) 

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. 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. Two public meetings were held during the public comment period – a meeting to 

discuss the TMDLs in general in Newport Beach on April 16, 2002, and a meeting to discuss 

specific technical issues in Irvine on May 9, 2002. Copies of the TMDLs and TSDs were 

available at the public meetings, in EPA and Regional Board offices, and on the EPA Region 9 

TMDL website. 

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Newport Bay Toxic Pollutant TMDLs 

Changes in the Final TMDL Documents 

Several changes were made in the final TMDLs in response to comments received during 

the comment period: 

•	 The numeric targets for some pollutants were modified to follow California screening 

guidelines or to reflect the most recent screening value studies. The organophosphate 

pesticide TMDL targets are based on values calculated by the California Department 

of Fish and Game. The California Office of Environmental Health Hazard 

Assessment guidelines were applied for organochlorine pollutant fish tissue targets. 

More recent literature values were applied for the freshwater organochlorine sediment 

targets. 

•	 The flow records used to calculate flow tiers for several pollutant TMDLs were 

changed to reflect a longer period of record and to incorporate more recent flow data. 

•	 The selenium TMDLs for the highest flow tier are based on acute water quality 

standards because, based on analysis of the longer flow record, flow patterns 

necessary to apply chronic standards were not expected to occur under the highest 

flow tier. 

•	 The metals TMDLs for San Diego Creek are concentration-based; the metals TMDLs 

for Newport Bay are both concentration-based and mass-based. 

•	 The organochlorine pollutant TMDLs were revised based on additional modeling 

analysis and consideration of more recent data. The flow tier approach applied for 

San Diego Creek organochlorine pollutant TMDLs was slightly modified. The 

description of analytical methods used for the organochlorine pollutant, chromium, 

and mercury TMDLs was revised to more clearly explain the analytical methods. 

•	 The allocation methods used for each TMDL were clarified. 

•	 A new section of implementation and monitoring recommendations was added to 

assist the State in preparing to adopt and implement TMDLs for these pollutants. 

summary document 11 
 

Newport Bay Toxic Pollutant TMDLs 

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, 

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Newport Bay Toxic Pollutant TMDLs 

•	 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, 2002). 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. EPA also considered whether TMDLs might be necessary based on evaluation of 

water quality trends and conditions in water segments adjacent to a segment in question. 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 bodypollutant 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 (see EPA 

Region 9, 2000). 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 

summary document 13 
 

Newport Bay Toxic Pollutant TMDLs 

pollutant TMDLs include the designated uses and both narrative and numeric water quality 

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 the 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 

the potential for 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. Chlorpyrifos and diazinon are not listed as toxic pollutants pursuant to 

Section 307(a)(1) of the Clean Water Act (see 40 CFR 401.15), and the CTR did not establish 

numeric objectives for those pollutants. Additionally, the CTR did not establish aquatic life 

objectives for 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 

summary document 14 
 

Newport Bay Toxic Pollutant TMDLs 

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 

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

recommendations. In the draft TMDL document, EPA proposed TMDLs based on the 

promulgated CTR standards, but invited comment on the alternative approach of basing the Se 

TMDLs on the more protective targets proposed by the Regional Board. The final TMDLs are 

based on the promulgated CTR standards. (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 often 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). Moreover, selection of targets based on these media enabled EPA to 

more completely utilize site specific data for several pollutants for which water column data 

were limited, consistent with the provisions of 40 CFR 130.7(c)(1)(i). 

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. The sediment and tissue 

numeric targets are probably more protective than the numeric objectives for these pollutants. 

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 both numeric and narrative standards are attained as 

required by 40 CFR 130.7(c)(1). 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 (EPA Region 9 2000). 

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. 

summary document 15 
 

 

Newport Bay Toxic Pollutant TMDLs 

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

guidelines developed by several studies (Long et al. 1995, Smith et al.1996, MacDonald et al. 

1996) and compiled by Long and MacDonald in the biological effects database system (BEDS) 

synthesizing many, many samples throughout North America. These sediment quality guidelines 

(equivalent to threshold effect levels) have been endorsed by NOAA in the screening quick 

reference tables (SQuiRTs) for contaminants in sediments (Buchman 1999). Where fish or 

shellfish tissue indicators are used, they are based on tissue screening values established by the 

California Office of Environmental Health Hazard Assessment (OEHHA 1999). 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 1986 and 2000c) 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 CDFG values for chlorpyrifos and 

diazinon at the recommendation of the Regional Board. 

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 erosion and 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. These TMDLs include wasteload allocations for some of these 

facilities. 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. Finally, the statewide general permit for industrial stormwater 

discharges covers several facilities that may discharge in the Newport Bay watershed, including 

John Wayne Airport. Runoff from state highways is regulated through the statewide CalTrans 

NPDES permit. 

summary document 16 
 

 

Newport Bay Toxic Pollutant TMDLs 

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. 

Table 2-1: NPDES Permits In San Diego Creek/Newport Bay Watershed 

NPDES permits in San Diego Creek 

watershed 

Comments 

Orange County Stormwater MS4 Permit; Includes many cities as co-permittees 

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

is currently drafting an individual permit 

Silverado Constructors/GW cleanup General permit, discharges under emergency 

conditions only 

Irvine Ranch Water District Individual permit, discharges tertiary treated water 

into Sand Canyon Reservoir and permit regulates 

stormwater overflows from Sand Canyon Reservior 

Serrano Water Treatment Plant Individual permit for a drinking water filtering plant 

City of Tustin groundwater desalter Individual permit, irregular discharges 

Great Lakes Chemical/GW cleanup Individual permit, no longer discharges 

CalTrans Stormwater Statewide permit for CalTrans facilities 

Industrial Stormwater Statewide general permit for industrial stormwater 

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 (for Hines and El Modeno) and Marshburn Channel (for 

Bordier’s) 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. 

summary document 17 
 

Newport Bay Toxic Pollutant TMDLs 

TMDLs and Allocations 

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

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. 

For several pollutants, insufficient information was available to support delineation of individual 

WLAs for each NPDES-permitted discharge. Therefore, the TMDLs include wasteload 

allocations for a category of “other NPDES permittees.” This wasteload allocation category 

covers discharges under the following permits: 

• Tustin Marine Base groundwater 

• Silverado Constructors 

• Irvine Ranch Water District 

• Serrano Water Treatment Plant 

• City of Tustin desalter 

• Great Lakes Chemical 

• Statewide Industrial Stormwater 

• Statewide Construction Stormwater 

EPA is establishing the grouped allocations for the “other NPDES permittees” category 

based on the following assumptions, which are discussed here to provide information to assist in 

implementing the allocations through the NPDES permitting process. The State, in consultation 

with the permittee(s) where appropriate, should gather data and information necessary to 

characterize the discharge flows and, if feasible, the loads of the specific pollutants for which 

allocations are established. The State should consider this new data and information when it 

considers adoption of the TMDLs and associated implementation plans for these toxic pollutants. 

If this categorical wasteload allocation is not subdivided when the State adopts the TMDLs, we 

assume that when any permit in this category is considered for revision or reissuance, the State 

should prepare an analysis as part of the permit fact sheet that (1) identifies the specific 

proportion or amount of the categorical wasteload allocation that can be discharged by the 

individual discharger, and (2) shows that the sum of all discharges covered by these permits will 

not exceed the total categorical wasteload allocation and is otherwise consistent with the 

TMDLs. Several alternative approaches are available to the State to apportion available loading 

amounts among the facilities covered in this wasteload allocation category (see Technical 

Support Document for Water Based Toxics Control, (EPA-505-2-9-001), March, 1991, pp. 68-69 

for guidance on allocation criteria). 

In the absence of additional analysis by the State in support of individual permitting 

actions consistent with the assumptions discussed above, we assume that available loading 

capacity identified in the categorical wasteload allocation is to be divided equally among the 8 

permitted discharges. We expect that the followup State analysis in support of TMDL adoption 

summary document 18 
 

Newport Bay Toxic Pollutant TMDLs 

or permit reissuance may result in different divisions of allocation capacity depending upon the 

combination of discharge flows, loads, and timing associated with each permitted discharge. 

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

specific dischargers or as “gross allotments” to nonpoint source discharger categories (40 CFR 

130.2). TMDLs usually provide separate load allocations for natural background loads. Separate 

load allocations for background loads are calculated for the Newport Bay metals TMDLs; 

however, insufficient information is available to support a conclusion that these loads are 

completely natural. Separate natural background allocations are inappropriate for pesticides and 

organochlorine compounds because they of anthropogenic origin and because all known loading 

sources are accounted for in the TMDL analysis. 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. 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 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: Load allocations and the stormwater wasteload allocation for San Diego Creek 

were generally divided in proportion to land areas associated with each source category. 

In defining the wasteload allocations for San Diego Creek, we considered the relative 

discharge flows associated with the different dischargers. We also included an 

undefined sources load allocation as a gross allotment to account for apparent loadings 

that could not be associated with other source categories. 

•	 Organochlorine Compounds: Allocations to terrestrial 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. Newport Bay allocations are 

expressed as net available loads, taking into account as background loads loadings 

already allocated for “upstream” segments. For this reason, the allowable loads as 

expressed in the allocation tables in the TMDL document do not increase cumulatively 

in a downstream direction. The division of available loading capacity between 

terrestrial and in-Bay sediment sources was done 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 

summary document 19 
 

 

Newport Bay Toxic Pollutant TMDLs 

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

percentage of estimated contributions from new sources and resuspended sediments. 

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. 

summary document 20 
 

Newport Bay Toxic Pollutant TMDLs 

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 

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 organochlorine 

(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 USGS from 1977 - 79 and 

1983 – 85 and Orange County Public Facilities and Resource Division (OCPFRD) from 1985 to 

present. EPA and Regional Board staff reviewed the entire daily mean flow record set from 

USGS and OCPFRD. The analysis was performed on a water year basis (e.g., July 1977 to June 

1978). Incomplete USGS data for the period 1979/80 to 1982/83 were not used because only 

partial records were available for each year. Thus, the USGS and OCPFRD records yielded 19 

water years of daily mean flow records for San Diego Creek. This time span covered water 

years: 1977-78, 1984/85 – 2000/01. EPA used these records for calculating the flow based 

approach to Se, dissolved metals, organochlorine, mercury and chromium TMDLs. EPA used 

annual flow records for water year 1996, 1997, 1998, 1999, 2000, 2001 to determine flow inputs 

from Santa Ana Delhi Channel. This time span covers a reasonable diversity of rainfall 

conditions based on precipitation measurements from 1958 to 2001. It includes the exceptionally 

wet El Nino year, 1998, as well as relatively drier years, 1999 and 2000. Table 2-2 shows 

summary document 21 
Newport Bay Toxic Pollutant TMDLs 

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. 

Table 2-2. Annual Precipitation Records at Tustin-Irvine Ranch Station

Water Rainfall Water Rainfall Water Rainfall Water Rainfall 

Year * (inches) Year (inches) Year (inches) Year (inches) 

1958-59 5.03 1971-72 5.02 1983-84 10.47 1995-96 11.17 

1959-60 9.6 1972-73 14.9 1984-85 10.25 1996-97 16.19 

1960-61 4.13 1973-74 9.81 1985-86 14.42 1997-98 34.72 

1961-62 13.07 1974-75 12.36 1986-87 8.79 1998-99 8.6 

1962-63 5.76 1975-76 5.11 1987-88 11.14 1999-00 8.8 

1963-64 9.38 1976-77 10.2 1988-89 8.17 2000-01 14.6 

1964-65 10.28 1977-78 27.96 1989-90 5.93 Summary 

1965-66 12.68 1978-79 18.59 1990-91 11.23 Min: 4.13 

1966-67 14.22 1979-80 20.75 1991-92 17.18 Max: 34.7 

1967-68 8.58 1980-81 8.47 1992-93 27.09 Mean: 13.03 

1968-69 19.91 1981-82 13.22 1993-94 10.23 Median: 10.8 

1969-70 8.48 1982-83 25.92 1994-95 24.65 Count: 42 

Source: OCPFRD; *Water years run from July 1 to June 30 of the following year. 

Rainfall data for water year 1970-71 not available 

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 studies relevant 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 2-3. 

Table 2-3 Overview of monitoring data 

Organization

Lee & Taylor

(2001a) 

319(h) report 

(for SA RWQCB) 

 Period of 

record

Winters 

1999; 

2000 

Geographic 

Scope 

San Diego Creek 

Watershed 

Measured 

Features

stormwater runoff 

Measured

Parameters and comments

Se; metals and OP pesticides in 

watershed, 

Draft report provided May 2001 

 summary document 22 
 

 

 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

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 

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 Imported 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 

summary document 23 
 

Newport Bay Toxic Pollutant TMDLs 

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 San Diego Creek during baseflow (200 ng/L) and 

stormflow (445 ng/L) have exceeded the chronic numeric target of 50 ng/L. Ninety-five percent 

of the observed concentrations were also above the acute numeric target of 80 ng/L. Average 

chlorpyrifos concentrations in San Diego Creek during baseflow (111 ng/L) and stormflow (87 

ng/L) have exceeded the chronic numeric target (14 ng/L). At least 59% of the observed 

concentrations also exceeded the acute numeric target of 20 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 

observed in Upper Newport Bay (43.3 ng/L) have exceeded the saltwater chronic numeric target 

of 9 ng/L during stormflow conditions, and 80% of the concentrations exceeded the acute 

numeric target (20 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. 

summary document 24 
 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

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 

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, b). 

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 recommended acute and chronic 

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

freshwater and saltwater (CDFG 2000a). 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. 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 

Pesticide Criterion 

 Concentration (ng/L) 

Freshwater Saltwater 

Diazinon Chronic 50 N/a 

Diazinon Acute 80 N/a 

Chlorpyrifos Chronic 14 9 

Chlorpyrifos Acute 20 20 

from Calif. Fish & Game (2000a) 

 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. 

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

summary document 25 
 

Newport Bay Toxic Pollutant TMDLs 

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. 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. 

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 

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). 

summary document 26 
 

Newport Bay Toxic Pollutant TMDLs 

Based on data from investigations carried out from 1996-20001, about 36 pounds of 

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

than 0.4% of the estimated diazinon mass applied in the watershed. About 8 pounds of 

chlorpyrifos is discharged annually to San Diego Creek and Upper Newport Bay, with most of 

the load delivered during storm events. This amounts to about 0.03% of the 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 loadings. Contributions from 

sediment remobilization and groundwater are negligible, however, loading from atmospheric 

deposition to Upper Newport Bay is potentially significant, though not well quantified. 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 

loading capacity via mass based 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 

summary document 27 
 

Newport Bay Toxic Pollutant TMDLs 

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 (9 

ng/L), and a maximum 1-hour average (acute) concentration of 20 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). The WLA applies to point sources 

in the watershed, and includes the NPDES permittees. The LA applies to non-point sources such 

as agriculture, open space and atmospheric deposition. 

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 discharges into other freshwater tributaries 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. 

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

Category Diazinon (ng/L) 

Acute Chronic 

Chlorpyrifos (ng/L) 

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 

summary document 28 
 

Newport Bay Toxic Pollutant TMDLs 

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 18 8.1 

Load allocation 18 8.1 

MOS 2.0 0.9 

TMDL 20 9 

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. 

Multiple samples are available from five separate storm events in the watershed from 1997-2000. 

The storm average concentrations in Table 3-4 are the maximum single storm averages at the 

San Diego Creek-Campus station. 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 

Campus Station 

Allocation Needed Reduction 

Chlorpyrifos 

 Storm Average 

(ng/L) 

Max 

(ng/L) 

Chronic 

(ng/L) 

Acute 

(ng/L) 

Chronic 

(ng/L) 

Acute 

(ng/L) 

120 580 12.6 18 90% 97% 

Diazinon 848 960 45 72 95% 93% 

Phase out agreements 

Diazinon – In January 2001, USEPA released a revised risk assessment and an 

agreement with registrants to phase out most diazinon uses (USEPA 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. In addition, on a national basis, about one-third of the 

agricultural crop uses will be removed. Within the Newport Bay watershed, non-agricultural and 

non-nursery uses account for over 90% of the diazinon use in Orange County. It is thus likely 

summary document 29 
 

Newport Bay Toxic Pollutant TMDLs 

that the EPA agreement will result in the cessation of most diazinon use in the Newport Bay 

watershed soon after the outdoor non-agricultural use registration expires on December 31, 2004. 

Chlorpyrifos – In June 2000, the EPA published its revised risk assessment and 

agreement with registrants for chlorpyrifos (USEPA 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 will be reduced, 

and public health use for fire ant eradication and mosquito control will be restricted to 

professionals. In Orange County, residential use likely accounts for over 90% of total 

chlorpyrifos use. Thus, it appears that over 90% of the current chlorpyrifos use in the Newport 

Bay watershed will be eliminated by the EPA agreement. Retail sales are scheduled to stop by 

December 31, 2001, and structural uses will be phased out by December 31, 2005. 

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

resulting discharge concentrations to the waterbodies, additional measures may 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 

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 

summary document 30 
 

Newport Bay Toxic Pollutant TMDLs 

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. 

summary document 31 
 

Newport Bay Toxic Pollutant TMDLs 

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). 

Moreover, selenium may be leached from sediments as a result of irrigation practices, elevation 

of the groundwater table, or other modifications in the natural hydrologic regime. 

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 μg/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 μg/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 selenium) 

are currently in progress (SCCWRP 2001a, b). 

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 (20 mg/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 to 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 2000). 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 selenium 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). EPA and Regional Board staff have re-evaluated freshwater flow histories for nearly 20 

water year records (see TSD part B). These records have been divided into four flow tiers as 

shown in Table 4-3 for San Diego Creek. Our re-evaluation indicates that mean water residence 

time of 4 consecutive days occurs in flow rates below 814 cfs. Thus the CTR chronic target (5 

summary document 32 
 

 

Newport Bay Toxic Pollutant TMDLs 

μg/L) applies to base, small and medium storms. During the large flows, shorter residence time 

(<4 days) exists and so an acute value is applied, 20 μg/L. EPA has incorporated this high flow 

(or “large storm”) value into selenium targets, flow tiers and loading capacity. 

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 three of four flow tiers in San 

Diego Creek and in Newport Bay. These are equivalent to the chronic freshwater and saltwater 

objectives included in the CTR. The acute freshwater objective is from National Toxics Rule 

(NTR, USEPA 1997) and is applied for the highest flow tier for San Diego Creek because the 

frequency of flows in this tier exceeds 4 days fewer than once in three years on average. 

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, and it is not 

clear whether the freshwater criteria will need to increase or decrease in order to protect aquatic 

life and aquatic dependent species. On one hand, several commenters supported the option of 

basing the TMDLs on more stringent targets based on the analysis provided by USFWS. On the 

other hand, several commenters identified site specific characteristics of Newport Bay watershed 

which could support a conclusion that objectives less stringent than the CTR would be 

protective. In light of these uncertainties concerning the need to either lower or raise the 

selenium standard, we concluded that it would be appropriate to set the TMDLs based on the 

existing numeric standard. The evidence that the CTR objectives are not be protective of San 

Diego Creek was not definitive enough to warrant selection of more stringent target values. 

Freshwater targets 

EPA is applying two numeric targets for different freshwater flow conditions in San 

Diego Creek. Based on re-evaluation analysis of daily flow records for water years 1977/78 and 

1985 to 2001, EPA divided all observed flows into 4 flow categories or tiers: baseflow (≤ 20 

cubic feet/second (cfs)), small flows (between 20 and 181 cfs), medium flow (between 181 and 

814 cfs), and large flow (>814 cfs). EPA is basing these TMDLs on a different period of flow 

record than proposed in the draft TMDLs because we have concluded that the flow record for 

1978/79 and 1983/84-2000/01 reflects more recently available data and is more reflective of long 

term flow patterns. The percentage of flows in the base, small and medium flow categories that 

exceeded 4 days in duration during this period far exceeded the once in 3 year recurrence interval 

that is assumed in calculation of selenium criteria. Therefore, it was appropriate to apply the 

more protective chronic standard under these flow conditions. During the high flows associated 

with large storms, the duration does not extend to four days more than once in 3 years on 

average, so it is appropriate to apply an acute target concentration for the high flow tier (20 μg/L, 

based on National Toxics Rule [USEPA 1999]). The Technical Support Document—Part B 

provides a complete explanation of these flow tiers and the associated mean annual flow volumes 

for calculating loads. 

summary document 33 
 

Newport Bay Toxic Pollutant TMDLs 

Saltwater target 

The numeric target for dissolved selenium in saltwater is 71 μg/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. Additionally, 

since San Diego Creek is the major contributor of freshwater flows to Newport Bay (>95%), 

reductions of selenium in the creek should also result in reductions in the Bay. 

Table 4-1. Numeric targets for Selenium in San Diego Creek and Newport Bay (μg/L). 

Waterbody/type Total Se* Dissolved Se# 

Acute Chronic 

San Diego Creek/freshwater 20 5 N/a 

Newport Bay & Rhine N/a N/a 71 

Channel/saltwater 

*Total recoverable = unfiltered sample 

#dissolved = <0.45 μm filter 

Source Analysis 

Several monitoring studies, completed with a specific focus on selenium during short 

time periods, provide most of our current understanding of selenium 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 

2000). 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 

sources (cleanup and dewatering). Surface channels immediately downstream of nurseries were 

found to have low selenium concentrations during base flow conditions (Hibbs and Lee 2000, 

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 selenium sources are from the commercial nurseries or 

from sources existing upstream of the nurseries. During rain events, the selenium load from the 

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. 

summary document 34 
 

 

 

Newport Bay Toxic Pollutant TMDLs 

Table 4.2 Reported Selenium conc. in San Diego Creek and Santa Ana-Delhi Channel (μg/L) 

Location 

Lee and Taylor* 

5/31/00 

Hibbs and Lee¥ 

10/31/99 

IRWD@ 

12/97–3/99 

San Diego Creek 22.1 19 42.5 

(at Campus Dr.) 

Santa Ana-Delhi 11.9 --- ---

(at Irvine Ave.) 

*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 selenium 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 μg/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). There is some evidence that runoff from open space, hillsides, and 

agricultural lands are significant sources during rain events although this evidence is 

inconclusive. Groundwater seepage/infiltration, treated groundwater discharges, and 

groundwater dewatering discharges represent significant and constant sources. 

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. 

(Nurseries have been grouped with agricultural runoff in Table 4-5 for allocations.) 

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. 

summary document 35 
Newport Bay Toxic Pollutant TMDLs 

San Diego Creek 

This TMDL uses a flow-based approach to determine the loading capacity for selenium 

in San Diego Creek. This approach addresses contributions of selenium 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 Drive. (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 selenium 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 Volume* Se conc. Loading capacity 

flow associated with tier with tier per tier@

(cfs) (million cubic ft.) (ug/L) (lbs/yr.) 

Base flow 0—20 275.4 5 86 

Small flows 21—181 347.5 5 108.4 

Medium flows 182—814 357.6 5 111.6 

Large flows >814 468.8 20 585.4 

Total annual 1449.4 891.4 

amount 

*Annual mean volume based on USGS & OCPFRD records for water years: 1978, 1984 to 2001.

@Se per tier (lbs/yr) = flow volume (ft3

/yr) x desired Se target (ug/L) x conv. factor (6.243 x 10-8 lbs x L/mg x ft3)

Newport Bay 

The loading capacity for Newport Bay is presented in Table 4-4. This loading capacity is 

calculated using the selenium saltwater numeric target (71 μg/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 891.4 

Santa Ana Delhi 185.3¥

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 were for water years 1995/96 – 00/01 

*based on calculation of the CTR saltwater chronic value (71 μg/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. Allocations for San Diego Creek are 

inclusive and have been sub-divided into categories presented below and allocations outlined in 

 summary document 36 
 

Newport Bay Toxic Pollutant TMDLs 

Table 4-5. The loading capacity for Santa Ana Delhi has been defined to set an upper limit on 

selenium contributions from that waterbody into Newport Bay. 

TMDL = Σ (wasteload allocations) + Σ (load allocations) + Margin of Safety 

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 

EPA adopted the selenium allocation scheme developed by Regional Board staff for their draft 

selenium TMDL. 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 

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 not given a specific allocation due to the very 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 and can be considered accounted for in 

the explicit MOS. 

•	 Discharges from groundwater cleanup and groundwater dewatering are 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 as 

group allocations groundwater cleanup discharges and groundwater dewatering 

discharges. In addition, a separate wasteload allocation is provided to account for future 

new groundwater dewatering discharges. 

Table 4-5 shows the wasteload and load allocations for San Diego Creek. 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 selenium 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 loading-based TMDLs and allocations are more appropriate 

because prospective adverse effects associated with selenium are associated more with long term 

summary document 37 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

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. 

Table 4-5 Se allocations for San Diego Creek watershed 

Source Loading capacity 

(lbs/year) 

Current 

load # 

Estimated 

reductions 

Tier 1 Tier 2 Tier 3 Tier 4 Annual 

total* 

WLA 

MCAS Tustin 1.6 2.0 1.8 7.9 13.2 

GW clean up 6.2 7.8 7.5 36.9 58.4 

Silverado 

GW 

3.1 3.9 4.0 21.1 32.1 

GW dewatering 3.9 4.9 4.5 21.1 34.3 

Future GW 

facilities 

0.4 0.5 0.5 2.6 4.0 

Stormwater 

Permit 

0.4 1.0 1.0 5.3 7.6 

WLA subtotal 15.5 20.0 19.3 94.8 149.7 

LA 

All nurseries 3.1 3.9 4.0 21.1 32.1 

Ag runoff 5.4 7.3 8.0 44.8 65.6 

Undefined 

sources @ 

53.4 66.4 69.1 366.2 555.0 

LA subtotal 61.9 77.6 81.1 432.0 652.6 

Total 

allocations 

77.4 97.6 100.5 526.8 802.3 2443 67% 

MOS 89.1 

Total TMDL 891.4 

* sum of loading capacity for San Diego Creek only (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 

§ other GW facilities refers to future permits 

summary document 38 
 

Newport Bay Toxic Pollutant TMDLs 

Seasonal variation/Critical conditions 

As previously described, EPA is calculating these selenium 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. 89 lbs/year). 

Some of the uncertainty associated with calculation of the TMDL for selenium relates to 

freshwater flow rates. Given the revised time period (nearly 20 years of daily flow records for 

San Diego Creek), this uncertainty has been reduced. That is, the draft TMDLs were based on 

five years of OCPFRD flow data, whereas these final TMDLs are based on flow records for 19 

years that better represent the range of flows during wet and dry water years. 

summary document 39 
 

 

Newport Bay Toxic Pollutant TMDLs 

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 should be considered with caution in 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 in southern California, San Diego Creek waters exhibit a wide range of flow 

rates and hardness levels. Monitoring data show that 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., 814 cfs corresponds to 236 mg/L hardness). This inverse relationship between flow rate 

and hardness influences both acute and chronic metals numeric targets. 

summary document 40 
 

 

Newport Bay Toxic Pollutant TMDLs 

Based on re-evaluation of freshwater daily flow records measured at San Diego Creek at 

Campus (see TSD part B), EPA has identified four flow tiers for fresh water segments for use in 

TMDL calculation. 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 tier, 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 small and medium flow tiers EPA selected the highest flow value 

within this tier to determine the corresponding hardness value. For large flows, EPA used the 

median flow rate value to determine the corresponding hardness value. 

EPA is identifying numeric targets and TMDLs for both chronic and acute conditions. It 

is appropriate to set TMDLs for chronic conditions in the lower three flow tiers based on an 

analysis of flow durations. The chronic standards for metals were calculated based on the 

assumption that flows of 4 days or longer in duration would reoccur no more than once in three 

years on average. Our analysis of the flow records showed that in each of the lower three tiers, 

the recurrence frequency of flows lasting 4 days or longer was greater than once in three years. 

For the highest flow tier, the recurrence frequency of flows lasting 4 days or longer was less than 

once in three years. Therefore, TMDLs are set for the high flow tier based solely on acute 

standards, which apply regardless of flow duration. 

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) 

Flow volume associated 

with tier # 

(million cubic ft.) 

Flow rate used to 

determine 

hardness 

Corresponding 

Hardness 

(mg/L) 

Base flow 0 - 20 275.4 N/a* 400 

Small flows 21 - 181 347.5 181 322 

Medium 

flows 

182 - 814 357.6 814 236 

Large flow >814 468.8 1595 197 

# mean volume for each tier based on daily flow records for 19 water years: 1977/78, 83/84 to 00/01.
 

(combination of USGS and OCPFRD data) 

* 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 both acute and chronic conditions for base, small and 

medium flows and for acute conditions only in large flows (>814 cfs). Given that water 

residence time is longer than four days during most of the year, we anticipate the chronic targets 

summary document 41 
 

Newport Bay Toxic Pollutant TMDLs 

will be most important for compliance, however, the acute targets also set an upper limit for 

input concentrations. 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. 

Table 5-2. Metals Numeric Targets (ug/L) based on flow tiers for San Diego Creek. 

Dissolved 

Metal 

Base Flows 

(<20 cfs) 

hardness @ 400 mg/L 

Small Flows 

(21 - 181 cfs) 

hardness @ 322 mg/L 

Medium Flows 

(182 -815 cfs) 

hardness @ 236 mg/L 

Large Flows 

(>815 cfs) 

@ 197 mg/L 

Acute Chronic Acute Chronic Acute Chronic Acute 

Cd 19.1 6.2 15.1 5.3 10.8 4.2 8.9 

Cu 50 29.3 40 24.3 30.2 18.7 25.5 

Pb 281 10.9 224 8.8 162 6.3 134 

Zn 379 382 316 318 243 244 208 

Note: actual ambient hardness must be determined for each monitoring sample regardless of which 

flow condition exists 

Saltwater bodies 

In saltwater systems, EPA uses the chronic dissolved metals numeric targets to develop 

mass based TMDLs. Saltwater targets are straightforward since hardness is not involved. The 

dissolved saltwater targets are outlined in Table 5-3. Additional numeric targets have also been 

selected to address toxicity in saltwater sediments. These sediment targets are the threshold 

effect levels for saltwaters as defined by NOAA SQuiRTs (Buchman 1999). Sediment metal 

concentrations below these target values are likely to alleviate toxicity to benthic organisms. 

Both 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; NOAA TEL values for sediments) 

*Cd value applies to 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. 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. 

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 sitespecific 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 

summary document 42 
 

Newport Bay Toxic Pollutant TMDLs 

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. 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 metal-contaminated 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, insufficient data were available to accurately estimate annual loads from each 

source. 

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 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 relatively 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 

summary document 43 
 

 

 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

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. 

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 

 Santa Ana –Delhi 

15,087 

1643 

6261 

682 

1643 

185 

682 

77 

Pb San Diego Creek 

 Santa Ana –Delhi 

10,385 

1297 

3977 

497 

449 

124 

172 

47 

Zn San Diego Creek 

 Santa Ana –Delhi 

63,021 

7031 

20,985 

2341 

3784 

805 

1260

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: runoff from open spaces, nursery 

and agricultural applications, groundwater dewatering and cleanup, and atmospheric deposition. 

Monitoring data exist for background 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 open spaces because the area upstream 

from this site is essentially undeveloped. Much of the metals loading associated with open 

spaces is probably naturally occurring; however, it is likely than some portion of loads from 

these areas is human caused (e.g., from atmospheric deposition or historic land use activities). 

Based on State pesticide use reports (CDPR 1999) for some nurseries, applications of copper 

sulfate appears as the most prominent metal containing substance used in nurseries; 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 

summary document 44 
 

Newport Bay Toxic Pollutant TMDLs 

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 

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 streams 

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, comprises less than 1% of metal contributions to Upper 

and Lower Bay and can be considered accounted for in the explicit margin of safety. 

Loading Capacity/Linkage Analysis 

In the draft TMDLs, EPA outlined two options for defining dissolved metals loading 

capacity and associated TMDLs. These two options were to apply a concentration based or a 

mass based approach for to each water body. Based on our review of public comments and 

further analysis, we are establishing TMDLs based on concentration for San Diego Creek and 

both concentration and mass loads for Newport Bay as discussed below. 

San Diego Creek and tributaries 

The metals loading capacities and TMDLs for San Diego Creek are set on a concentration 

basis for dissolved metals. The rationale for addressing dissolved metals is that dissolved metal 

forms are the most bioavailable to aquatic organisms. These metals are generally not know to 

bioaccumulate from one organism to the next, nor has sediment toxicity attributed to metals in 

the Creek been reported; therefore, long term mass loading which could contribute to 

bioaccumulation or sediment toxicity concerns is less of an issue in San Diego Creek. For these 

reasons, a concentration-based approach is more appropriate for these pollutants. These 

concentration-based loading capacity will protect aquatic life from short term exposure via acute 

targets (for all flow conditions) and longer term exposure via chronic targets (for flows <814 

cfs). 

These concentration based loading capacity values are hardness dependent. Freshwater 

systems experience a wide range of flows and individual hardness conditions. In the future, it 

will be necessary to measure actual ambient hardness concurrent with each metals monitoring 

sample (grab or composite) in order to help determine compliance with the TMDLs. The CTR 

sets an upper limit for hardness is 400 mg/l; the lower recommended limit is 25 mg/l. 

summary document 45 
 

 

 

Newport Bay Toxic Pollutant TMDLs 

The acute and chronic targets and associated loading capacities and TMDLs apply to 

base, small and medium flows. However, targets, loading capacities, and TMDLs for the highest 

flow tier (>814 cfs) are based on acute standards only. As discussed above, this approach is 

based on our review of flow records for San Diego Creek to examine the duration of elevated 

flows and the frequency of chronic conditions (See TSD Part B for freshwater flow). 

Newport Bay 

For Upper and Lower Bay, including Rhine Channel, the loading capacities were 

calculated by multiplying 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). The mass-based 

loading capacity for all of Newport Bay is shown in Table 5-5a. (A complete description of this 

calculation is presented in TSD – Part E.) 

The rationale for setting mass-based metals TMDLs and allocations is to address 

observed sediment toxicity in all areas of Newport Bay. 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. The alternate metals sediment 

targets (Table 5-3) will help to evaluate acceptable conditions for benthic organisms. 

Mass based allocations set a definitive upper limit on the amount of each metal allowed 

to be discharged from San Diego Creek into Newport Bay, which would probably be most 

effective in addressing long term sediment toxicity concerns. Loading contributions from San 

Diego Creek and Santa Ana Delhi Channel were calculated by multiplying the chronic numeric 

target for base, small and medium flow tiers and acute target for large 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 TSD – Part E.) The sum of all four tiers 

yields the upper limit to the mass-based loading capacity for San Diego Creek (Table 5-5a). 

Table 5-5a. Mass-based dissolved metal loading capacity for Newport Bay 

Dissolved Metal Upper and Lower Bay 

including Rhine Channel 

Dissolved load (lbs/yr) 

Cd 14,753* 

Cu 11,646 

Pb 27,136 

Zn 285,340 

*Cd load applies to Upper Bay only, where volume of Upper Bay is approximately 40% of the total volume of 

Newport Bay 

To ensure that Newport Bay is protected from potential adverse effects of short term 

metals loading “spikes”, the loading capacities and associated TMDLs for Newport Bay are also 

defined in terms of the concentration-based water quality standards for the Bay. In the absence 

of this complementary approach, it would be possible for the Bay to meet the annual loadingsummary document 46 
 

Newport Bay Toxic Pollutant TMDLs 

based TMDL and still exceed water quality standards on a short term basis. The concentration 

based TMDLs are listed in Table 5.5b 

Table 5.5b Concentration-based dissolved metal loading capacity for Newport Bay 

Metal 

Dissolved saltwater 

acute loading capcity 

(ug/L) 

Dissolved saltwater 

chronic loading capacity 

(ug/L) 

Cd* 42 9.3 

Cu 4.8 3.1 

Pb 210 8.1 

Zn 90 81 

TMDLs and Allocations 

The freshwater dissolved metals TMDLs are concentration–based; whereas the saltwater 

TMDLs are both mass-based and concentration-based. The TMDLs and allocations may be 

expressed in terms of the following general equation: 

TMDL = Σ (wasteload allocations for point sources) + Σ (load allocations from non-point 

sources and background) + Margin of Safety 

San Diego Creek 

As discussed in the loading capacity section, EPA is expressing the San Diego Creek 

metals TMDLs on a concentration basis. The freshwater allocations are equivalent to the 

concentration-based targets, reduced by 20% to provide the margin of safety discussed below 

(see Table 5-6 for freshwater TMDLs and allocations). These allocations 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. Because flow tiers for the freshwater channels other than San Diego 

Creek were not specifically calculated, it is assumed that the same TMDLs applicable to San 

Diego Creek during different flow conditions apply to the other channels at the same times. For 

example, when flow is 50 cfs in San Diego Creek, the “small flows” TMDLs and allocations 

listed in Table 5-6 apply in all the other freshwater channels in addition to San Diego Creek. 

Table 5-6. Metals WLAs, and LAs in (ug/L) (based on flow tiers for San Diego Creek) 

Dissolved 

Metal 

Base Flows 

(<20 cfs) 

hardness @ 400 mg/L 

Small Flows 

(21 - 181 cfs) 

hardness @ 322 mg/L 

Medium Flows 

(182 -815 cfs) 

hardness @ 236 mg/L 

Large Flows 

(>815 cfs) 

@ 197 mg/L 

Acute Chronic Acute Chronic Acute Chronic Acute 

Cd 19.1 6.2 15.1 5.3 10.8 4.2 8.9 

Cu 50 29.3 40 24.3 30.2 18.7 25.5 

Pb 281 10.9 224 8.8 162 6.3 134 

Zn 379 382 316 318 243 244 208 

Values are 80% of freshwater numeric targets in Table 5-2 

Note: actual ambient hardness must be determined for each monitoring sample regardless of which flow 

condition exists 

summary document 47 
 

Newport Bay Toxic Pollutant TMDLs 

The wasteload allocations apply to the following NPDES discharges: 

•	 Orange County Stormwater 

•	 CalTrans 

•	 Other NPDES Discharges (see Section II, p. 19 for description of this allocation 

category) 

The load allocations apply to the following source categories: 

•	 Agricultural runoff (including nurseries) 

•	 Air deposition 

•	 Other sources (includes open space runoff, background, and undefined sources). 

Newport Bay 

Table 5-7a presents the mass based TMDLs and allocations for dissolved metals in 

Newport Bay. 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 (confined by line drawn 

from 20th St. across to Lido Beach St. to channel end). 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. 

Several methods were used to determine allocations. First, because NPDES boatyard 

permittees are not authorized to discharge into salt waters of Newport Bay, the wasteload 

allocation for boatyards is zero. Second, air deposition and undefined sources (background from 

medium and large storm runoff and ambient seawater contributions) were assigned mass 

loadings based on existing loading since reductions were not expected. Third, agriculture runoff 

was also assigned an explicit mass loading of one-half the total annual estimated loads based on 

the assumption that erosion control planned under the sediment TMDL implementation plan 

would result in approximately a 50% reduction in erosion-related metals loading, and that the 

small amount of metals load associated with agricultural chemical use could be reduced through 

use of best management practices (EPA, 1993). The allocations for the remaining sources (urban 

stormwater, CalTrans, other NPDES, and boats (for copper and zinc)) were based on best 

professional judgement, as discussed below, because insufficient data were available to 

accurately estimate their relative contributions to existing loads. The allocation for runoff from 

the watershed from urban stormwater and CalTrans facilities and discharges from the other 

NPDES permittee category is based on the assumption that approximately half the metals 

loading can be reduced through use of available management practices (EPA, 1993). The runoff 

allocation is divided between the Orange County stormwater permit, CalTrans permit, and other 

NPDES facility category based on the relative proportions of watershed land area under the 

jurisdiction of these three permits. The remaining allocation for boats represents a reduction in 

metals loadings from boats of greater than 80%, based on the assumption that changes in boat 

paint usage and maintenance practices could substantially reduce the direct loading of copper 

(and potentially zinc) into Bay waters (EPA 1993). Table 5-7b presents the concentration-based 

allocations for Newport Bay. 

summary document 48 
 

 

Newport Bay Toxic Pollutant TMDLs 

Table 5-7a. Mass-based Allocation Scheme for Metals in Newport Bay 

Category Type Copper Zinc Lead Cadmium* 

WLA Urban runoff 3,043 174,057 17,638 9,589 

CalTrans 423 22,866 2,171 1,185 

Boatyards 0 0 0 0 

Other NPDES 

permittees 

190 17,160 1,154 596 

Sub-total 3,656 lbs/yr 214,083 lbs/yr 20,963 lbs/yr 11,370 lbs/yr 

LA Ag runoff 215 114 0 0 

Boats 4,542 1,056 0 0 

Air deposition 101 606 68 4 

Undefined (open 

space, existing 

sed.) 

803 11,414 678 428 

Sub-total 5,661 lbs/yr 13,189 lbs/yr 746 lbs/yr 431 lbs/yr 

MOS 2,329 lbs/yr 57,068 lbs/yr 5,427 lbs/yr 2,951 lbs/yr 

Total 

TMDL 

11,646 lbs/yr 285,340 lbs/yr 27,136 lbs/yr 14,753 lbs/yr 

*values apply to Upper Bay only (estimated as 40% of Newport Bay volume) 

Table 5.7b Concentration-based dissolved metal TMDLs, WLAs, and LAs for Newport Bay 

Metal 

Dissolved saltwater 

acute TMDLs and allocations 

(ug/L) 

Dissolved saltwater 

chronic TMDLs and allocations 

(ug/L) 

Cd* 42 9.3 

Cu 4.8 3.1 

Pb 210 8.1 

Zn 90 81 

The concentration based WLAs and LAs apply only to the sources which discharge 

directly to the Bay, including stormwater discharges from stormdrains directly to Bay segments 

(such as Costa Mesa Channel and Santa Ana Delhi Channel) and metals loading associated with 

boats. The concentration-based WLAs and LAs for San Diego Creek and the other fresh water 

tributaries will address short term metals concentrations associated with discharges to the fresh 

water system. 

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. This is due to higher hardness levels during low flows that 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 

summary document 49 
 

Newport Bay Toxic Pollutant TMDLs 

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. 

For both San Diego Creek and Newport Bay, the approach of setting concentration based 

TMDLs and allocations based on chronic and acute targets helps address and mitigate any short 

term effect associated with brief periods of high metals loading. 

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.	 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. 

2.	 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). 

3.	 Setting both acute and chronic-based TMDLs and allocations for San Diego Creek and 

Newport Bay helps ensue that short-term toxic effects are not allow to occur even if 

longer term mass loading-based TMDLs and allocations are met. This approach helps 

ensure that water quality standards will be met throughout the year. 

summary document 50 
 

Newport Bay Toxic Pollutant TMDLs 

VI. Organochlorine TMDLs 

TMDLs are being established for chlordane, total DDT and total PCBs in all waterbodies: 

San Diego Creek, Upper Bay, Lower Bay and Rhine Channel. Dieldrin TMDLs are being 

established for San Diego Creek, Lower Bay and Rhine Channel. A TMDL for toxaphene is 

being established for San Diego Creek only. The term “organochlorine compounds” includes all 

of these pollutants and 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 applicable narrative water quality standards are not being met. Specifically, 

toxaphene exceedances (87%, n=15) of the OEHHA tissue screening value occur only in San 

Diego Creek (TSM). Tissue exceedances have also occurred for Chlordane (40%), Dieldrin 

(93%), total DDT (93%), and total PCBs (67%) in San Diego Creek (n= 15 for all, TSM). 

Similar elevated fish tissue concentrations indicate bioaccumulation for Chlordane, Dieldrin, 

total DDT and total PCBs in all saltwater bodies of Newport Bay (except for dieldrin in Upper 

Bay). Conclusions for Newport Bay are based on finfish and shellfish tissue results from several 

monitoring efforts (SMW, TSM, 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 OEHHA tissue screening values are still occurring. Freshwater 

and saltwater tissue concentrations show declining trends, with higher levels generally occurring 

in San Diego Creek than in Newport Bay. The sediment data did not exhibit clear trends, rather 

erratic spikes, which is common for this heterogeneous media. 

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 is 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 salt waters; 

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 

and tissue screening values. 

summary document 51 
 

 

 

Newport Bay Toxic Pollutant TMDLs 

The use of sediment criteria in this analysis yields an environmentally conservative 

interpretation of water quality criteria, including the narrative water quality objectives in the 

Regional Board Basin Plan (1995). 

The numeric targets for freshwater and saltwater systems for chlordane, dieldrin, DDT, 

PCBs and toxaphene, are shown in Table 6-1a and 6-1b. The primary target value is based on 

sediment levels, and the alternate targets are provided for fish and shellfish tissues and for water 

column concentrations in freshwater. The specific numeric values for sediment targets were 

selected from NOAA Sediment Screening Quick Reference Tables (SQuiRTs) (Buchman 1999). 

By selecting sediment targets, EPA will address protection of benthic organisms as well as 

bioaccumulation of these organochlorine compounds into tissues of higher organisms such as 

fish, wildlife predators and humans. Sediment targets are used for TMDL development except 

where sediment data were not available; e.g., toxaphene in San Diego Creek. The alternate 

targets – fish tissue screening values from OEHHA and water column objectives from the CTR– 

are included in this TMDL report as means of gauging improvement in the water quality and 

progress towards achievement of the TMDL, and to assist in assessing the accuracy of the 

analysis supporting the TMDLs. 

Table 6-1a. Numeric targets for organochlorine compounds for all waterbodies. 

Waterbody Pollutant Sediment target ¥ 

(ug/dry kg or ppm) 

Fish tissue target# 

(ug/kg wet or ppb) 

San Diego Creek and Chlordane 4.5 30 

tributaries Dieldrin 2.85 2.0 

Total DDT 6.98 100 

Total PCBs 34.1 20 

Toxaphene 0.1* 30 

Upper and Lower Newport Chlordane 2.26 30 

Bay, and Rhine Channel Dieldrin 0.72 2.0 

Total DDT 3.89 100 

Total PCBs 21.5 30 

*this value assumes 1% total organic carbon in sediment sample 

¥sediment targets equivalent to threshold effect levels (TEL) from Buchman 1999, except toxaphene from NY 

Dept. Environmental Conservation 

#all tissue targets from OEHHA 

Numeric targets for water column concentrations are provided in Table 6-1b based on 

CTR criteria. These concentrations apply to freshwater bodies (USEPA 2001a); numeric 

objectives are not available for several of the pollutants in saltwater. We used these targets when 

modeling the maximum allowable concentrations for water-associated loads from particulate 

pollutants. (See modeling and analysis section). 

Table 6-1b. Freshwater column target values for organochlorine compounds. 

Pollutant CMC (acute) CCC (chronic) 

(μg/L) (μg/L) 

PCBs -- 0.014 

DDT * 1.1 0.001 

Chlordane 2.4 0.0043 

Dieldrin 0.24 0.056 

Toxaphene 0.73 0.0002 

* DDT value cited for 4,4’ DDT, but value will apply to one one isomer or sum of all isomers detected 

summary document 52 
 

Newport Bay Toxic Pollutant TMDLs 

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 except in association with 

erosion of sediments to which these pollutants may have adhered in the past. The source 

analysis is therefore 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. 

Available data and analyses indicate that there is an existing “reservoir” of historicallydeposited organochlorine pollutants in Newport Bay sediment, to which continuing relatively 

low levels of ongoing pollutant loads are contributing from the watershed. The main source of 

continuing loadings of organochlorine compounds in the Newport Bay watershed is estimated to 

be erosion of surface soils or in-stream sediments to which these pollutants have adsorbed 

(binded). Sediment-adsorbed pollutants 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 

reported. 

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. 

Insufficient data were available to estimate the loads from these sources. Ground water-related 

loading is expected to be minor because only a small proportion of organochlorine pollutant 

loads generally occurs in dissolved form. On the other hand, resuspension of sediments to which 

organochlorine pollutants have adhered is likely to be a more important “loading” source. 

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. Masters and Inman (2000) 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 

summary document 53 
 

Newport Bay Toxic Pollutant TMDLs 

pesticides and deposit them in a different location in the watershed, to stream systems, 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. No local “hot 

spots”-specific locations with highly elevated levels of OC pesticides-- were identified. 

The only potentially active application of any of the OC pesticides identified is the 

application of Dicofol, a registered pesticide that may contains small amounts of DDT (i.e., up to 

.015% based on its registered formulation). The actual DDT content of Dicofol, if any, is 

unknown. The DPR pesticide use database indicates that Dicofol (trade name “Kelthane”) was 

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 and aquatic 

sediments), Dicofol is not estimated to be a significant source of DDT to Newport Bay. 

However, because DDT in low concentrations may pose an continuing ecological concern, it 

may be appropriate to further investigate and reduce possible runoff of DDT associated with 

Dicofol. 

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 caused sediment contamination and that the 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. Based on our review of limited 

information about PCB spills and waste sites containing PCBs, we hypothesize that accidental 

PCB spills, which were most likely to have occurred at the El Toro and Tustin Air Stations as 

well as other hazardous waste sites, are the most likely historical loading source of PCBs. 

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 

This section describes the methods used to determine the loading capacity and to estimate 

the existing loads for each organochlorine contaminant with respect to each waterbody. The 

modeling approach and various resources utilized to complete these tasks are outlined here, 

although more details, such as equations and specific values, are provided in the Technical 

Support Document – Part F. To the extent possible, we used hydrologic and modeling 

information previously compiled by Resource Management Associates (RMA 1997, 1998, 1999) 

for the U.S. Army Corp of Engineers (ACOE). This model provides sediment deposition 

information used to determine both loading capacities and estimate existing loads for (for the 

Upper and Lower Bay, including Rhine Channel. RMA model calibration results were utilized 

because these results incorporate circulation patterns, spatial distribution and net settling rates for 

summary document 54 
 

 

 

Newport Bay Toxic Pollutant TMDLs 

each area of Newport Bay. These RMA results were generated using a wide spectrum of flow 

rates from San Diego Creek addressing a 12 year time span (1985 to 1997). Thus the RMA 

model has implicitly addressed sediment transport and resuspension in Newport Bay as well as 

dry and wet weather conditions and flow rates in San Diego Creek. 

Within San Diego Creek, the RMA model does not provide more specific data such as 

spatial distribution of sediments, so sediment deposition and the corresponding pollutant load 

must be estimated via stream flow rates. EPA used nearly 20 water years of flow records for San 

Diego Creek. The time span of daily flow rates covers water years 1977/78 and 1984/85 - 00/01. 

This is discussed more in TSD Part B – Flow and consistent with flow records used in Se and 

dissolved metals TMDLs. For the OC TMDLS, three flow tiers were used -- low flow (0 to 181 

cfs), medium (between 181 and 814 cfs) and high flow (>814 cfs). This was designed to 

represent conditions during dry weather and very light rains (low flow events), intermediate 

storms (medium flows) and those large storms (high flows) when extensive sediment transport 

occurs. Pollutants associated with fine particles (especially clay) and dissolved phase are 

assumed present in all three flow tiers. 

Loading capacity 

San Diego Creek 

For the listed OC pollutants in San Diego Creek the loading capacities were calculated 

based on pollutant contributions from water column and sediments. The sediment associated 

loading capacity was determined from target sediment concentrations and sediment load 

estimates, which were based on regression results presented in RMA model (1997) to link flow 

rates with sediment loads. We estimated the associated water column loading capacity by 

backcalculating, from sediment loads to particulate concentrations and dissolved concentrations, 

using partition coefficients. Where appropriate, these water column derived loads were 

constrained by chronic water targets for low and medium flows and acute targets for large flows. 

The sum of the allowable loads in particulate form and dissolved form represents the loading 

capacity in San Diego Creek. The loading capacities are presented as long term annual loading 

estimates consistent with the patterns of sediment deposition in the system. Loading capacities 

for San Diego Creek are presented in Table 6-2. 

Newport Bay 

The loading capacity for Newport Bay relied on RMA (1998) sediment deposition budget 

and bottom sediment conditions with target concentrations. The Bay was sub-divided into 

discrete areas for which individual loading capacities were calculated and summed to provide 

loading capacities for each water body of the Bay (Upper, Lower and Rhine). To determine the 

particulate associated load, several factors were used and included: saltwater sediment target, 

net sediment deposition (volume), porosity, and sediment density. Sediment volume is 

converted to dry weight by an estimated porosity (0.65). The net loading capacities are 

presented as average mass per year for each water body to reflect the long-term accumulation 

patterns associated with sediment and pollutant accumulation in Newport Bay. Loading 

capacities for Newport Bay are presented in Table 6-3. 

summary document 55 
 

 

Newport Bay Toxic Pollutant TMDLs 

Existing Loads 

San Diego Creek 

A slightly different approach was required to estimate the existing loading to San Diego 

Creek. Due to incomplete sediment monitoring data for all organochlorine pollutants in San 

Diego Creek, we used recent fish tissue results (TSM data from 1998) to help estimate water and 

(indirectly) sediment loads. Water column associated loads were back calculated by using 

pollutant- and fish species- specific bioconcentration factors (BCFs). The particulate load was 

estimated from these water column derived values using partition coefficients. The sum of the 

particulate and water column associated loads yields the estimated existing loads for San Diego 

Creek based on the most reliable and current data for these hydrophobic compounds. Existing 

loading estimates for San Diego Creek are presented in Tables 6-5. 

Newport Bay 

The methods used to estimate existing loads in Newport Bay were similar to those 

described earlier for loading capacity in Newport Bay. Fortunately, more monitoring data exists 

for Newport Bay and, in particular recent sediment data (OCPFRD 1999/00 and SCCWRP 

2001a) was maximized to give more representative or current conditions in each portion of the 

bay. These monitoring results were used with the RMA sediment deposition budget to yield the 

existing pollutant loads. Resuspension and recirculation of sediments, along with the water 

associated load was implicitly included since these conditions were included in the RMA 

approach for Newport Bay. (Upper and Lower Bay existing loads represent the sum of several 

individual areas, as defined in Appendix Table 3 in TSD – Part F.) The net pollutant existing 

loading estimates for Newport Bay segments are presented in Tables 6-6 to 6-8. 

Loading Capacity/Linkage Analysis 

The loading capacity for each pollutant was calculated for San Diego Creek, Upper and 

Lower Bay, and Rhine Channel. The loading capacity for each water body was derived as 

described above and in the Technical Support Document – Part F. The loading capacity was 

determined to define the maximum amount of loading which could occur and still result in 

attainment of the sediment targets, and at the same time, not exceed water quality targets. The 

model takes into consideration such factors as the particulate and dissolved contributions and 

flow rates in San Diego Creek. In Newport Bay, the loading capacities were determined via the 

RMA model and target sediment concentrations. The OC compound loading capacities for San 

Diego Creek and Newport Bay are listed in Tables 6-2 and 6-3, respectively. 

The loading capacity was determined to define the maximum amount of loading which 

could occur and still result in attainment of the sediment targets. The model links estimates of 

ongoing pollutant contributions from the watershed with existing pollutant concentrations in the 

bottom sediments and predicts the cumulative effects in terms of future pollutant concentrations 

in the bottom sediments and associated trends. The model takes into consideration such factors 

as the existing water column concentrations (either observed or calculated based on fish or 

mussel tissue concentrations), data and modeling of sediment deposition into the water bodies, 

decay rate for a pollutant in the water column, thickness of the water column and active sediment 

layer, sediment resuspension rates, and sediment burial rates. 

summary document 56 
 

Newport Bay Toxic Pollutant TMDLs 

Table 6-2. Loading Capacity for San Diego Creek 

Pollutant Name 

Sediment Target 

Concentration 

(ug/kg dry) 

Loading 

capacity 

(g/year) 

Chlordane 4.5 314.7 

Dieldrin 2.85 261.5 

DDT 6.98 432.6 

PCBs 34.1 2226 

Toxaphene 0.1 8.9 

Table 6-3. Estimated Loading Capacity for Newport Bay 

Waterbody 

Sediment Target 

Concentration (ug/kg dry) 

Loading Capacity 

(g/year) 

Chlordane Dieldrin DDT PCBs Chlordane Dieldrin DDT PCBs 

Upper Bay 2.26 0.71 3.89 21.5 160.4 N/A 276.5 1528.2 

Lower Bay* 2.26 0.71 3.89 21.5 59.2 18.6 101.85 562.9 

Rhine 

Channel 2.26 0.71 3.89 21.5 1.7 0.53 2.92 16.2 

(This table is summary of information presented in Table F-4 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. For each organochlorine compound, the 

loading capacity in each waterbody is equal to the sum of allocations and an explicit margin of 

safety. Identification of the TMDL is based on a comparison of the existing loading with the 

loading capacity. In situations where existing loadings are less than the loading capacity, the 

TMDLs and allocations are set at the existing loading levels in order to ensure that the TMDL 

targets are eventually met, and to ensure that pollutant levels in the sediments do not increase in 

the future (defined as Condition 1 in Table 6-4 below). In situations where existing loads are 

greater than the loading capacity, the TMDLs and allocations are set equal to the loading 

capacity (after subtracting the explicit margin of safety). This situation is defined as Condition 2 

in Table 6-4 below. Table 6-4 identifies the decision rules applied for each water segment and 

OC pollutant to define the individual TMDLs. 

Table 6-4. Decision rules applied to define TMDLs based on condition applicable to each 

waterbody/pollutant combination. 

Pollutant San Diego 

Creek 

Upper 

Newport Bay 

Lower 

Newport Bay 

Rhine Channel 

Chlordane 

Dieldrin 

DDT 

PCBs 

Toxaphene 

Condition 2 

Condition 2 

Condition 2 

Condition 1 

Condition 2 

Condition 2 

NL 

Condition 2 

Condition 1 

NL 

Condition 1 

Condition 1 

Condition 2 

Condition 1 

NL 

Condition 1 

Condition 2 

Condition 2 

Condition 2 

NL 

NL: Not listed for this pollutant 

summary document 57 
Newport Bay Toxic Pollutant TMDLs 

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. For most 

pollutant/waterbody combinations, the loading capacity value is less than the existing load and 

thus the loading capacity determines the TMDL, as seen in Table 6-4. A 10% margin of safety 

was subtracted from the loading capacity or existing load, whichever is smaller value. 

Table 6-5. Summary of San Diego Creek Loadings and TMDL 

Pollutant Existing Load1 Loading Capacity2 TMDL Margin of Safety 

(g/year) (g/year) (g/year) (g/year) 

Chlordane 615.7 314.7 314.7 31.5 

Dieldrin 381.8 261.5 261.5 26.2 

DDT 3733.8 432.6 432.6 43.3 

PCBs 282.1 2226 282.1 28.2 

Toxaphene 582.1 8.9 8.9 0.9 

1 existing load based on observed data (OCPFRD 1999/00 and SCCWRP 2001a) 

2 loading capacity based on sediment targets 

TMDL is lesser value of existing load or loading capacity; TMDL = Total allocation + MOS 

Table 6-6. Summary of Upper Newport Bay Loadings and TMDL 

Pollutant Existing Load1 Loading Capacity2 TMDL Margin of Safety 

(g/year) (g/year) (g/year) (g/year) 

Chlordane 290.7 160.6 160.6 16.1 

DDT 1080.2 276.5 276.5 27.7 

PCBs 858.7 1528.2 858.7 85.9 

1 existing load based on observed data (OCPFRD 1999/00 and SCCWRP 2001a) 

2 loading capacity based on sediment targets 

TMDL is lesser value of existing load or loading capacity; TMDL = Total allocation + MOS 

Table 6-7. Summary of Lower Newport Bay Loadings and TMDL 

Pollutant Existing Load1 Loading Capacity2 TMDL Margin of Safety 

(g/year) (g/year) (g/year) (g/year) 

Chlordane 50.2 59.2 50.2 5.0 

Dieldrin 5.9 18.6 5.93 0.59 

DDT 438.4 101.85 101.8 10.2 

PCBs 409.8 562.95 409.8 41.0 

1 existing load based on observed data (OCPFRD 1999/00 and SCCWRP 2001a) 

2 loading capacity based on sediment targets 

TMDL is lesser value of existing load or loading capacity; TMDL = Total allocation + MOS 

Table 6-8. Summary of Rhine Channel Loadings and TMDL 

Pollutant Existing Load1 Loading Capacity2 TMDL Margin of Safety 

(g/year) (g/year) Allocation (g/year) 

(g/year) 

Chlordane 0.33 1.70 0.33 0.3 

Dieldrin 3.76 0.53 0.53 0.05 

DDT 5.60 2.92 2.92 0.23 

PCBs 70.0 16.2 16.2 1.6 

1 existing load based on observed data (SCCWRP 2001a) 

2 loading capacity based on sediment targets 

TMDL is lesser value of existing load or loading capacity; TMDL = Total allocation + MOS 

 summary document 58 
 

 

Newport Bay Toxic Pollutant TMDLs 

Tables 6-9, 6-10, 6-11, and 6-12 present the allocations for each OC pollutant-waterbody 

combination. The explicit margin of safety (10%) has been included for clarification. 

Allocations were assigned for sources to San Diego Creek primarily in proportion to land use 

area. The allocations to nurseries and other agriculture factor in two considerations. First, it was 

assumed that erosion control activities pursuant to the sediment TMDL implementation plan 

would result in approximately a 50% reduction in OC pollutant runoff from agriculture. In 

addition, these load allocations factor in a small amount of possible DDT loading associated with 

possible DDT content in the pesticide Dicofol. The allocations are based on the assumption that 

only a small fraction of Dicofol reaches water ways, and that DDT loading to waterways 

associated with Dicofol is a minor source. Undefined sources (existing sediments, air deposition, 

possible groundwater contributions) were assigned 3% based on existing loading estimates. The 

remaining portion (approximately 72%) was allotted to urban runoff. We estimate that erosion 

control practices will result in substantial reduction in OC pollutant loadings associated with 

eroded sediments (EPA, 1993). 

PCBs are particularly stable in aquatic sediment, so we assigned a slightly higher 

percentage of available allocations to undefined sources (10%) and 4% to other NPDES permits 

because PCBs chemicals are more likely to be present in groundwater and therefore they may be 

contained in discharges of groundwater clean up and treatment facilities. This quantity may be 

modified in subsequent TMDL revisions after subsequent monitoring with adequate sampling 

and analytical methods to verify PCB loads. 

Table 6-9. Allocations for San Diego Creek watershed 

Category Type DDT (including 

Dicofol) 

Chlordane Dieldrin PCBs Toxaphene 

WLA Urban 

runoff 

302.8 220.3 183.4 177.7 6.2 

Caltrans 8.7 6.3 5.2 42.3 0.2 

Other 

NPDES 

permittees 

34.6 25.2 21.0 5.6 0.7 

Sub-total 346.1 g/yr 251.8 g/yr 209.6 g/yr 225.6 g/yr 7.1 g/yr 

LA Ag runoff 8.6 6.2 5.2 5.6 0.2 

Undefined 

* 

34.6 25.2 21.0 22.6 0.7 

Sub-total 43.2 g/yr 31.4 g/yr 26.2 g/yr 28.2 g/yr 0.9 g/yr 

MOS 43.3 g/yr 31.5 g/yr 26.2 g/yr 28.2 g/yr 0.9 g/yr 

Total 

TMDL 

432.6 g/yr 314.7 g/yr 262.0 g/yr 282.0 g/yr 8.9 g/yr 

*undefined = existing sediments + air deposition 

Total TMDL = WLA + LA + MOS 

summary document 59 
 

 

 

 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

Table 6-10. Allocations for Upper Newport Bay 

Category Type DDT (including 

dicofol) 

Chlordane PCBs 

WLA Urban runoff 207.4 120.5 609.7 

CalTrans 2.8 1.6 8.6 

Other NPDES 

permittees 

2.8 1.6 8.6 

Sub-total 212.9 g/yr 123.7 g/yr 626.9 g/yr 

LA Ag runoff 2.8 1.6 8.6 

Undefined* 33.2 19.3 137.4 

Sub-total 35.9 g/yr 20.9 g/yr 146.0 g/yr 

MOS 27.7 g/yr 16.1 g/yr 85.9 g/yr 

Total TMDL 276.5 g/yr 160.6 g/yr 858.7 g/yr 

*undefined = existing sediments + air deposition 

Total TMDL = WLA + LA + MOS 

Table 6-11. Allocations for Lower Newport Bay 

Category Type DDT (including 

dicofol) 

Chlordane Dieldrin PCBs 

WLA Urban runoff 76.3 12.6 4.45 303.3 

CalTrans 0 0 0 4.10 

Other NPDES 

permittees 

0 0 0 0 

Sub-total 76.3 g/yr 12.6 g/yr 4.45 g/yr 304.7 g/yr 

LA Ag runoff 0 0 0 0 

Undefined* 15.3 32.6 0.89 61.5 

Sub-total 15.3 g/yr 32.6 g/yr 0.89 g/yr 73.8 g/yr 

MOS 10.2 g/yr 5.0 g/yr 0.59 g/yr 41.0 g/yr 

Total TMDL 101.8 g/yr 50.2 g/yr 5.93 g/yr 409.8 g/yr 

*undefined = existing sediments + air deposition 

Total TMDL = WLA + LA + MOS 

Table 6-12. Allocations for Rhine Channel 

Category Type DDT Chlordane Dieldrin PCBs 

WLA Urban runoff 0.7 0.1 0.13 4.1 

Other NPDES 

permittees 

0 0 0 0 

Sub-total 0.7 g/yr 0.1 g/yr 0.13 g/yr 4.1 g/yr 

LA Undefined* 1.9 0.21 0.34 10.5 

Sub-total 1.9 g/yr 0.21 g/yr 0.34 g/yr 10.5 g/yr 

MOS 0.3 g/yr 0.03 g/yr 0.05 g/yr 1.6 g/yr 

Total TMDL 2.9 g/yr 0.33 g/yr 0.53 g/yr 16.2 g/yr 

*undefined = existing sediments + air deposition 

Total TMDL = WLA + LA + MOS 

summary document 60 
 

Newport Bay Toxic Pollutant TMDLs 

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. The explicit margin 

of safety is intended to address uncertainties in the relationship between OC pollutant loadings 

and environmental responses in different areas of the watershed. 

In addition, EPA is providing an implicit margin of safety through the selection of several 

conservative analysis approaches and assumptions used to calculate the TMDLs. Insufficient 

information is available to specifically 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 recommendation of 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 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 (0.65) were slightly lower than those used to estimate 

historical loads (0.80) by RMA. 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 

OC pollutants are of potential concern in the Newport Bay watershed due to possible long 

term loading and food chain bioaccumulation effects. There is no evidence of short term 

potential effects. However, pollutant loads and transport within the watershed may vary under 

different flow and runoff conditions. Therefore the TMDLs consider seasonal variations in loads 

and flows but are established in a manner which accounts for the longer time horizon in which 

ecological effects may occur. 

summary document 61 
 

Newport Bay Toxic Pollutant TMDLs 

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 budget developed by RMA (1998) 

which incorporates various flow regimes throughout each year. The sediment budget (generated 

via model) represents various weather patterns and flow conditions for 12 years. 

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 organochlorine compounds are manifested 

over long time periods in response to bioaccumulation in the food chain. Therefore, short term 

loading variations (within the time scale of wet and dry seasons each year) are not likely to cause 

significant variations in beneficial use effects. 

summary document 62 
 

Newport Bay Toxic Pollutant TMDLs 

VII. Chromium and Mercury TMDLs 

TMDLs are being established for chromium (Cr) and mercury (Hg) only for the Rhine 

Channel area of Lower Newport Bay. 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), providing some evidence of chromium 

bioaccumulation (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=6). The mercury levels in the limited number of available samples were very 

high (e.g., recent data shows 5.3 ppm versus PEL level 0.7 ppm). Sediment toxicity has been 

consistently reported for Rhine Channel (BPTCP 1997, SCCWRP 2001a) although specific 

contaminants causing this toxicity have yet to be identified. 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 applied 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 

MacDonald et al. 1996 and cited in NOAA SQuiRTs (Buchman 1999). For comparison, the 

TEL value is much lower than the probable effects level (PEL = 0.696 mg/kg dry). The NOAA 

Effects Range-Low (ERL) value for mercury (ERL = 0.15 mg/kg dry) is close to the TEL target 

value. The alternate mercury numeric target is fish tissue (0.3 mg/kg wet methylmercury), from 

EPA proposed criteria and analysis provided in the USFWS Biological Opinion on the CTR 

(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, Buchman 1999) as the best available target to 

summary document 63 
 

Newport Bay Toxic Pollutant TMDLs 

protect both wildlife predators and benthic organisms. The alternate chromium 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 

Rhine Channel 

Chromium (Cr) 

Mercury (Hg) 

52 0.2 

0.13 0.3* 

*mercury tissue target is interpreted as 0.3 mg/kg wet methylmercury (EPA proposed criteria and 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. The Regional Board has 

documented two previous investigations of metals contamination at Newport Plating Company. 

These investigations found extremely high levels of chromium in sediment boring samples. 

Furthermore, a storm drain which drains runoff from the Newport Plating facility area discharges 

into Rhine Channel. This facility should be considered a potential source and should receive 

further investigation. More complete information on this source is presented in TSD part G – 

Chromium and Mercury. 

Chromium may also be leaching from treated wood pylons in marine areas (Weis et al. 

1991). Chromium is a naturally occurring element in many area, 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. 

The heavily contaminated sediments in Rhine Channel are most likely associated with historic 

discharges from industrial facilities around Rhine Channel, and these legacy sources are likely to 

be the largest current sources of chromium. 

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 

summary document 64 
 

Newport Bay Toxic Pollutant TMDLs 

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 is the historical 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 may have flowed to Peters Canyon Wash. 

Other minor sources of Hg deposits have been mapped in the area. At this time, no additional 

information is available to accurately assess whether mercury from this mining location reached 

the Rhine Channel area. However, available evidence for all of Newport Bay suggests that 

mercury levels in the rest of Newport Bay are not elevated. It is unlikely that mercury loads 

from the upper watershed would have contributed to mercury contamination of Newport Bay 

sediments solely in the Rhine Channel area. Therefore, it is unlikely that discharges from the 

Red Hill mine area are a principal cause of mercury contamination in Newport Bay. 

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 kg/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 Rhine Channel 

(kg/yr) 

Cr ‘97-99 16 46.9 

Hg ‘97-99 0.0186 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. 

summary document 65 
 

Newport Bay Toxic Pollutant TMDLs 

Modeling 

The approach to determining the loading capacities for mercury and chromium is similar 

to the approach used for the organochlorine compounds (TSD – Part F) and was based on an 

understanding of the sources of these compounds (past, present, and future) and the transport and 

ultimate fate of these compounds in various environmental media. Based on a review of 

literature sources, it was observed that mercury and chromium environmental persistence and 

affinity for adsorbing to sediment and accumulating in biota generally limits their presence in the 

water column, at least relative to sediment and biota. 

Previous modeling studies, completed by RMA for the U.S. Army Corps of Engineers 

(USACE) have examined the circulation patterns, and transport and deposition of sediments in 

Newport Bay (RMA 1997, 1998). By examining model calibration results (RMA 1997) for 

Newport Bay from 1985-1997, the sediment deposition in Rhine Channel was estimated. The 

approach relies on the following key information: sediment deposition rates, deposition patterns 

(from the RMA (1997) model), pollutant targets (used for loading capacity) (see TSD Table G-2) 

and sediment moritoring data for mercury and chromium concentrations (used for existing loads) 

(see TSD, Table G-1 and Appendix 1) Historic pollutant loads to the bottom sediment were 

estimated by using observed pollutant concentrations in bottom sediments and net sedimentation 

rates. Sediment volume was converted to dry weight using an estimated porosity of 0.65. The 

loading capacities were determined by “back-calculating” the allowable load from the selected 

sediment target (Table 7-3) and the associated estimates of sediment loads. 

Loading Capacity/Linkage Analysis 

Determination of loading capacity has been described above and uses similar methods to 

those outlined for organochlorine TMDLs (see Section VI of this document and TSD Part G for 

more comprehensive explanation. These TMDLs express the loading capacities, TMDLs, and 

allocations in mass loading terms for Rhine Channel. Because most of the mercury and 

chromium loads are associated with contaminated sediments already in Rhine Channel, it will be 

necessary to remediate contaminated sediments in order to meet water quality standards and 

prevent adverse ecological effects. 

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. 

For mercury, the on-going load, which is associated principally with local contaminated 

sediments, is higher than the estimated loading capacity. Therefore, the mercury TMDL (0.10 

kg/yr )and associated allocations are set based on this loading capacity. The opposite is true for 

chromium, where the existing load is slightly lower than the loading capacity, therefore the 

summary document 66 
Newport Bay Toxic Pollutant TMDLs 

chromium TMDL is based on 33.1 kg/yr. The loading capacities for chromium and mercury are 

expressed as annual averages (Table 7-3). 

Table 7-3. Historical Loading and Estimated Loading Capacity for Rhine Channel 

Pollutant existing conc. * Estimated Load Sediment Target Loading Capacity 

(mg/kg dry) (kg/yr) (mg/kg dry) (kg/yr) 

Chromium 44 33.1 52 39.1 

Mercury 5.8 4.36 0.13 0.10 

* (SCCWRP 2001a) 

The wasteload and load allocations (Table 7-4) were calculated based principally on best 

professional judgement . Most of the available loads were assigned to sediments already in 

Rhine Channel, which are by the far the largest source. These allocations to existing sediments 

reflect substantial reductions in sediment loads from in-Channel sources based on the expected 

effectiveness of remedial actions identified in the 1997 remedial action plan. The remaining 

available load was allocated roughly in proportion to the land areas associated with the 

remaining source categories after allocating 5% of available loads for undefined sources. Further 

investigation of Newport Plating facility may warrant revision of such a high allocation to 

sediments in Rhine Channel for Chromium. 

Table 7-4. Rhine Channel Wasteload and Load Allocations (kg/yr) and % of total loads

Mercury (Hg) Chromium (Cr) 

Wasteload allocations 

Stormwater 0.0171 (19%) 5.66 (19%) 

Caltrans 0.0027 (3%) 0.89 (3%) 

Boat yards 0 0 

Other NPDES permittees 0.0027 (3%) 0.89 (3%) 

Load allocations: 

Existing sediment 0.063 (70%) 20.85 (70%) 

Undefined sources: air 0.0045 (5%) 1.49 (5%) 

deposition, ambient seawater 

Margin of safety 0.01 3.30

TMDL 0.1 kg/yr 33.1 kg/yr 

TMDL = WLA + LA + MOS 

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 

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 

 summary document 67 
 

Newport Bay Toxic Pollutant TMDLs 

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 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) (0.65) were slightly lower 

than those used (0.80) in RMA model. 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) 

which incorporates various flow regimes throughout each year. The model represents various 

weather patterns and flow conditions for 12 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. 

summary document 68 
 

Newport Bay Toxic Pollutant TMDLs 

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 

summary document 69 
Newport Bay Toxic Pollutant TMDLs 

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 Org. n Min Max Mean Median 

dates 

San Diego 1995 -- 98 TSMP 15 0.06 0.88 0.18 0.13 

Creek 

Newport 1995 -- 98 TSMP* 4 0.4 8.6 2.93 1.3 

Bay 1999 -- 00 CFCS 26 0.2 4.0 1.29 0.79 

(finfish) 2000 - 01 SCCWRP 50 0.22 8.6 1.64 0.68 

(shellfish) 1995 - 00 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 

Finfish 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 

Great Britain 720 0.9 – 30.1 5.6 4.3 

Shellfish Newport Bay 24 0.8 – 2.5 1.3 1.3 

Wash State 10 1.0 – 6.9 2.4 2.2 

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 results from various North American waterbodies (1996) 

Great Britain results from Collins et al. 1996 

 summary document 70 
 

Newport Bay Toxic Pollutant TMDLs 

IX. Implementation Recommendations 

This section provides general recommendations of implementation actions and 

monitoring work to assist in implementing the TMDLs and allocations identified in this decision. 

Several commenters, including the Regional Board, dischargers, and environmental groups 

specifically requested that EPA discuss TMDL implementation recommendations when we made 

the final TMDL decisions. The implementation and monitoring actions are not required and are 

not part of the TMDL decisions being made by EPA at this time; rather, they are included with 

the TMDLs to assist followup planning and implementation work by the State and local 

stakeholders. As discussed in Section I above, the State—not EPA—is responsible for 

developing implementation plans necessary to attain TMDLs. In its comments concerning the 

EPA TMDLs, the Regional Board signaled its commitment to adopt TMDLs and implementation 

plans for these toxic pollutants in a timely manner. 

General Recommendations 

The toxic pollutant TMDLs address several pollutant types which come from a variety of 

sources. Therefore a range of pollutant management options will be available to the State to 

address them. Based on information we gathered in developing the TMDLs as well as feedback 

obtained from the State and local stakeholders during the development of the TMDLs, we have 

identified several appropriate implementation approaches for different pollutants. 

Consistent with the State’s approach to developing and implementing other TMDLs in 

the Newport Bay watershed for sediments, nutrients, and pathogens, EPA believes a phased, 

iterative approach to implementation and monitoring is appropriate to address the toxic 

pollutants of concern. Substantial uncertainty remains concerning pollutant sources and the 

relationship between pollutant loads and environmental effects in the watershed. EPA believes 

some specific implementation actions should be carried out to address pollutant sources which 

are most clearly of concern. Several of these actions are already underway or in the planning 

stages. It is also appropriate to collect and analyze additional monitoring data to improve the 

understanding of pollutant sources and effects, periodically review the TMDLs and 

implementation actions in light of new monitoring results, and revise the TMDLs and 

implementation actions if necessary. Depending upon the State’s priorities, additional 

monitoring data could also assist in reviewing and, if necessary revising the applicable water 

quality standards to provide the appropriate level of beneficial use protection. This combination 

of early actions to address clear pollutant sources and an ongoing commitment to iterative 

monitoring and adjustments provides an appropriate balance in followup implementation work. 

When the Regional Board considers adoption of TMDLs for toxic pollutants along with 

associated implementation plans, the State may adopt the TMDLs identified in this decision or 

further assess these pollutants and adopt different TMDLs if warranted. EPA recommends that 

the State consider the specific areas of analytical uncertainty identified in the analysis supporting 

our TMDL decisions as a starting point in targeting any additional analytical work (including 

monitoring) planned in support of TMDL adoption. 

It is expected to take several years for toxic pollutant levels in the watershed to decline to 

the point where all applicable water quality standards are fully attained. For some pollutants 

summary document 71 
 

 

Newport Bay Toxic Pollutant TMDLs 

such as the diazinon and chlorpyrifos, the pollutant levels will probably decline quickly in 

response to actions to reduce their use. For some other pollutants with long residence times in 

the environment, or which are associated with historical discharge, there will probably be some 

lag time between the initiation of controls to reduce loading or remediate contaminated sites and 

the observation of decreased pollutant levels throughout the watershed. For these reasons, EPA 

supports the past State practice of identifying interim targets or benchmarks in terms of pollutant 

control actions, pollutant loadings and/or receiving water responses to help ensure that control 

actions are taken and progress is being made toward attaining water quality standards. 

Specification of clear interim targets also assists in the evaluation of whether the TMDLs or 

implementation actions need to be adjusted in the future. 

EPA’s TMDLs do not contain compliance timeframes or interim implementation targets 

because these elements are addressed by the State in the implementation planning process. EPA 

urges the State to work with local dischargers and stakeholders to design and carry out effective 

implementation actions sufficient to implement the TMDL in a timely manner. 

As discussed in Section 1, the Clean Water Act creates federal regulatory jurisdiction 

only over point sources. Therefore, the direct implementation effect of EPA’s TMDLs is that 

when NPDES permits for point source discharges are issued or revised for discharges to waters 

in the watershed, the State is required to ensure that the permits contain effluent limitations 

necessary to be consistent with the wasteload allocations (WLAs) contained in theTMDLs (40 

CFR 122.44(d)). Permit modification may occur when existing permits are reopened or reissued, 

or when a new discharge source seeks a permit. NPDES permit holders should contact the 

Regional Board to discuss how and when action will be taken to implement applicable WLAs. 

The State has discretion to determine how the point source permit provisions will be made 

consistent with applicable WLAs. Depending upon the situation and the level of precision in the 

WLA, it may be appropriate to: 

•	 incorporate numeric effluent limitations for the pollutant(s) of concern in the permit, 

•	 identify best management practices and associated pollutant control effectiveness which 

demonstrate that the WLAs will be attained, and/or 

•	 require the discharger to submit a WLA compliance plan and schedule which 

demonstrates how the WLA will be implemented. 

In addition to addressing WLA implementation through the NPDES permitting process, the 

State should work with local stakeholders to identify specific actions necessary to carry out load 

allocations identified in the TMDLs. These actions may be based on voluntary or regulatory 

approaches. We note that CWA Section 319(h) nonpoint source implementation grant funds 

may be available to assist in implementing controls necessary to implement load allocations. 

Section 319(h) projects designed to implement TMDLs currently receive priority for funding. 

Landowners or land managers interested in seeking Section 319(h) funding assistance should 

contact the Regional Board staff for more information concerning the State’s grant funding 

process. 

OP Pesticide TMDL Implementation Recommendations 

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 

summary document 72 
 

Newport Bay Toxic Pollutant TMDLs 

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

approximately 90% of diazinon and chlorpyrifos use in the watershed is estimated to be 

associated with urban and household uses, the phase-out program may be sufficient to result in 

attainment of the TMDLs and associated allocations. We recommend that the Regional Board 

continue its work with nurseries in the watershed to minimize use of these pesticides. We 

recommend continued monitoring in San Diego Creek and its tributaries to assess reductions in 

OP pesticide runoff in the next several years. If monitoring demonstrates that the urban use 

phase-outs are inadequate to implement the TMDLs, it may be necessary in the future to 

implement additional controls on agricultural uses of these pesticides in coordination with the 

California Department of Pesticide Regulation 

We are concerned by potential conflicts between programs to reduce use of these 

pesticides and mandates to use these pesticides for fire ant control. EPA urges that Regional 

Board to work with the State Water Resources Control Board, California Department of 

Pesticide Regulation, California Department of Food and Agriculture, and EPA’s pesticide 

program to assess and, if necessary, reconcile these potentially conflicting mandates concerning 

OP pesticide use. 

Selenium TMDL Implementation Recommendations 

EPA is in the process of reviewing and potentially revising the numeric criteria for Se in 

freshwater. In addition, other local studies are underway to assess the potential effects of Se on 

aquatic organisms. EPA expects to complete this review within approximately 2 years. EPA 

recommends that the State review and, if necessary, revise the Se TMDLs following adoption or 

promulgation of the revised water quality standards. Several commenters raised concerns about 

whether the CTR criteria are appropriate for conditions in the San Diego Creek watershed, and 

identified several local factors (e.g. local water chemistry) which could support consideration of 

alternative site specific criteria. In consultation with EPA and the State Water Board, the 

Regional Board should consider whether it is feasible and appropriate to assess the applicable Se 

water quality standards in light of these concerns, and potentially adopt site specific water 

quality standards. 

The TMDL analysis found that the most significant sources of Se loading appear to be 

associated with groundwater entering surface waters (sometimes directly and sometimes through 

discharge from dewatering operations). Control of these sources will be difficult. However, 

EPA recommends that the State begin working with permitted dischargers to assess options for 

reducing Se discharges through discharge management practices and/or treatment technologies. 

The State may wish to sequence its planning activities to settle issues concerning applicable 

standards before carrying out actions to further tighten discharge controls. 

EPA recommends that the Regional Board monitor flow and Se concentrations in 

discharges from cleanup and ground water dewatering operations in order to provide the basis for 

establishing effluent limits in the permits consistent with the TMDLs. When NPDES permits for 

groundwater cleanup or dewatering operations are considered, the Regional Board will need to 

ensure that the total allowable Se loadings do not exceed the group WLA established in the 

TMDL. 

summary document 73 
 

 

Newport Bay Toxic Pollutant TMDLs 

Metals TMDL Implementation Recommendations 

Metals loading in the watershed is associated primarily with ongoing runoff from urban 

and undeveloped areas, and aquatic sediments containing previously discharged metals. Our 

recommendations address all the metals for which TMDLs are established, including mercury 

and chromium. EPA recommends five areas of action to address metals loading in the 

watershed. 

First, metals levels in the Rhine Channel area are estimated to be substantially higher 

than in other areas of the watershed. No significant ongoing loading sources were identified, 

and the aquatic sediments in Rhine Channel have been identified as a significant toxic hot spot. 

EPA recommends aggressive action to complete and implement the contaminated sediment 

remediation plan initiated by the State and Regional Boards in 1997. One potential ongoing 

source of concern with respect to chromium loading is the Newport Plating facility. EPA 

recommends that the State further assess this facility and, if necessary, carry out discharge 

controls or remedial actions necessary to address any ongoing loadings. 

Second, the source analysis indicated that copper leaching from boat paints is probably a 

significant source of copper loading to the Bay. In coordination with marina and boatyard 

operators, other Regional Boards, the State Board, and EPA, the Santa Ana Regional Board 

should develop specific actions to reduce the use of copper-containing boat paints or their 

leaching to water bodies through use of additional boat storage and maintenance practices. 

Third, the Regional Board should work with the stormwater discharge permittees to 

further assess the potential effectiveness of available management practices to reduce metals 

loading in discharges of urban runoff under high and low flows. In future iterations of the 

stormwater permits, provision should be made to implement effective metals reduction practices, 

with particular emphasis on implementation of the more cost-effective methods identified. 

Additional work will be needed in the immediate future to more thoroughly assess and document 

the prospective effectiveness of available practices. 

Fourth, he State adopted a sediment TMDL and implementation plan in 1999 which 

called for an overall 50% reduction in sediment loading from San Diego Creek through 

implementation of a locally developed sediment reduction plan. Reductions in sediment loading 

should assist in reducing loadings of total metals. EPA recommends that the State continue 

implementation of this sediment reduction plan and monitor to determine whether both total and 

dissolved metals loading levels decline over time. 

Fifth, the State may wish to consider reevaluation of the metals criteria and associated 

TMDLs in the future based on application of criteria calculation methods which are currently 

under development. Metals criteria calculation protocols are nearing completion which may 

enable States to calculate metals standards that more accurately represent the bioavailable 

portion of total metals loading through consideration of water effects ratios (WERs). It may be 

relatively straightforward recalculate metals criteria based on local hardness and organic carbon 

data and revised WER equations. In light of the potential cost of extensive actions to further 

control metals loading from urban runoff in the watershed, EPA believes it may be reasonable to 

consider whether newly emerging criteria calculation methods would result in protective but 

easier-to-implement standards. 

summary document 74 
 

Newport Bay Toxic Pollutant TMDLs 

Organochlorine Compound TMDL Implementation Recommendations 

This TMDL decision addresses two types of organochlorine compounds whose use is no 

longer authorized: several chlorinated pesticides (DDT, chlordane, dieldrin and toxaphene) and 

PCBs, which were used in electrical equipment. Because these compounds are very stable in the 

environment and often adhere to sediments, they may continue to reach and remain in water 

bodies at levels of concern for many years following their discharge to the environment. Two 

potential routes of environmental exposure of these compounds are of greatest potential 

concern—ongoing loadings from the watershed of historically deposited pollutants and 

exposures to organochlorine compounds already present in aquatic sediments (principally in 

Newport Bay). There is substantial evidence indicating that levels of these compounds in Bay 

sediments and aquatic organisms has declined over the past 20 years or more. 

No terrestrial “hot spots” (locations with significantly elevated levels of these pollutants 

were located during the TMDL development process; however, limited historical information 

indicates that there may have been some spills (e.g., PCB spills at El Toro and Tustin Air 

Stations). We recommend that the State conduct more thorough investigations of potential spill 

sites based on the preliminary information compiled for this TMDL effort in order to determine 

whether there are any significant hot spot sites in the watershed warranting further remedial 

action. 

The most likely source of ongoing loading of organochlorine pollutants is erosion of 

sediments to which these compounds have adhered. The State adopted a sediment TMDL and 

implementation plan in 1999 which called for an overall 50% reduction in sediment loading from 

San Diego Creek through implementation of a locally developed sediment reduction plan. EPA 

recommends that the State continue implementation of this sediment reduction plan and monitor 

to determine whether levels of organochlorine compounds continue to decline. Monitoring 

should examine not only the levels of organochlorine pollutants in the water column, but also 

sediment running into tributary streams, sediment moving down San Diego Creek, and sediments 

in Newport Bay. 

If future monitoring indicates that declines in levels of the pollutants in the watershed are 

continuing or accelerating, it may be unnecessary to implement additional erosion and sediment 

controls. If the levels of these pollutants in sediments and tissue do not decline or actually begin 

to rise, the State will need to revisit and potentially revise terrestrial sediment control strategies 

in the watershed as a whole and aquatic sediment management strategies in the Bay. 

summary document 75 
 

Newport Bay Toxic Pollutant TMDLs 

Newport Bay sediment and tissue monitoring programs should continue to test for 

organochlorine pollutants. Although no obvious aquatic sediment “hot spots” were found for 

these pollutants (with the possible exception of Rhine Channel for some pollutants), the available 

data appear to indicate that the reservoir of these pollutants still found in Bay sediments far 

outweighs the additional loads to the Bay from the watershed. Therefore, in coordination with 

monitoring and assessment programs to evaluate the full suite of toxic pollutants of concern, the 

State should continue to consider whether any specific locations warrant remedial action to 

remove, cap, or otherwise immobilize Bay sediments. It is always important to consider whether 

the long term benefit of aquatic sediment remedial action is outweighed by the potential short 

term adverse effects associated with disturbing contaminated sediments. The remedial action 

plan adopted by the State for Rhine Channel should help reduce any ongoing availability of these 

pollutants at that location, and we repeat our recommendation that this remedial action plan be 

carried out in a timely manner. 

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. Restoration is scheduled to begin in 

2003/2004. We recommend that the State work with the project sponsors to ensure that potential 

disturbance of sediments containing the pollutants addressed in this TMDL report is considered 

in the design process and minimized during project implementation. 

Monitoring Recommendations 

This action establishes TMDLs for numerous toxic pollutants, in a watershed for which 

several other TMDLs have previously been established. We recommend that the State work with 

the other State and federal agencies, the County, permitted cities, local industries, and perhaps 

local academic institutions to develop a coordinated monitoring program for Newport Bay and 

its tributary streams. While much of this work could be carried out pursuant to the NPDES 

stormwater permit, the scope of the monitoring needed to more fully characterize toxic pollutant 

trends in the watershed and the effectiveness of pollutant control strategies goes beyond the 

scope of traditional monitoring required under these permits. Substantial monitoring has 

conducted in the past but it was (with the exception of the County’s monitoring) usually 

relatively narrow in scope in terms of pollutant coverage, geographical extent, and temporal 

scope. Newport Bay watershed is a good candidate for development of a more integrated and 

comprehensive monitoring approach which could result in a more cost-effective overall approach 

to monitoring than currently created by independent monitoring approaches. 

We recommend that the State consider the areas of uncertainty in each TMDL analysis as 

discussed in the margin of safety sections and TSDs in order to identify the types of monitoring 

data which are most important to reduce analytical uncertainty and improve our ability to target 

meaningful control actions. 

summary document 76 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

X. 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. 

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California Department of Food and Agriculture (CDFA) 1999 Red Imported Fire Ant. California Action Plan. 

March. 

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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, 

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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. 

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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. 

Long, ER, DD MacDonald, DD; SL Smith and FD Calder 1996 Incidence of Adverse Biological Effects with 

Ranges of Chemical Concentrations in Marine and Estuarine Sediments. Environ. Mgmt. 19:1 pp. 81-97. 

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. 

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Muller, FLL 1996 Interactions of copper, lead and cadmium with the dissolved, colloidal and particulate 

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criteria for piscivorous wildlife. NYDEC, Division of Fish and Wildlife, Bureau of Environemtnal Protection 

Technical Report 87-3, 182p. 

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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. 

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 

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RMA 1997 Upper Newport Bay Feasibility Report—Final model and GUI development and implementation 

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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 

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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. 

summary document 79 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

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. 

SCCWRP 2001b Newport Bay Fish Bioaccumulation Study—Progress Report.(for contract with Santa Ana 

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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 

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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 

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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 

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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 

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US Fish & Wildlife Service 2000 Biological Opinion on EPA’s “Water Quality Standards: Establishment of 

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US Fish & Wildlife Service 1998 Guidelines for Interpretation of the Biological Effect of Selected Constituents in 

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US Geological Survey 2000 Stormflow Chemistry in the Santa Ana River below Prado Dam and at the Diversion 

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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. 

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Priority Toxic Pollutants for the State of California; Federal Register Rule—40CFR Part 131. U.S. 

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USEPA 2000b Chlorpyrifos Revised Risk Assessment and Agreement with Registrants. 

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USEPA 2000e Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health. 

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USEPA 1999a Environmental Risk Assessment for Diazinon. 

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Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Wash. DC. 

USEPA 1993. Guidance Specifying Management Measures For Sources of Nonpoint Pollution In Coastal Waters. 

EPA 840-B-92-002. U.S. Environmental Protection Agency, Office of Water, Washington DC. 

summary document 80 
 

 

 

 

 

 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

USEPA 1991 Guidance for Water Quality-based Decisions: The TMDL Process. EPA-440/4-91-001. Office of 

Water, Washington, DC. 

USEPA 1991b Technical Support Document for Water Quality-based Toxics Control. EPA-505-2-9-001. Office of 

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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 1980 Ambient Aquatic Life Water Quality Criteria: DDT. EPA-440/5-80-038. Office of Water, 

Washington, DC. 

USEPA Region 9 2002 Decision Document for Assessment of San Diego Creek and Newport Bay Water Quality 

USEPA Region 9 2000 Guidance for Developing TMDLs in California. 

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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. 

summary document 81 
 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

XI. 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 

summary document 82 
 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

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 

RIFA Red Imported Fire Ant 

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] 

summary document 83 
 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

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 

summary document 84 
 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

Appendix B 

Arsenic Fish Tissue Monitoring data 

 SPECIES NAME Date Total Inorganic 

Arsenic Arsenic 

 Screening Value OEHHA = 1.0 EPA = 1.2 

(mg/kg wet) 

#/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 Shiner Surfperch 06/00/2000 10 0.969 0.039 0.097 

PCH Br 

Newport Bay/above Spotted Turbot 06/00/2000 5 1.775 0.071 0.177 

PCH Br 

Newport Bay/above Yellowfin Croaker 06/00/2000 4 0.585 0.023 0.059 

PCH Br 

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 

summary document 85 
 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

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) 

count 80 

saltwater finfish results 

max 8.62 0.34 0.86 

mean 1.59 0.06 0.08 

median 0.78 0.03 0.08 

summary document 86 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

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) 

count 24 

Saltwater shellfish results 

max 2.50 0.04 

mean 1.28 0.02 

median 1.25 0.02 

summary document 87 
 

 

 

 

 

 

Newport Bay Toxic Pollutant TMDLs 

Tot. As 

Inorg. As 

TSMP data '96--'98 

San Diego Creek 

San Diego 

Creek/Michelson 

Peters Canyon 

Channel 

San Diego 

Creek/Barranca 

Delhi Channel 

San Diego 

Creek/Michelson 

Peters Canyon 

Channel 

Peters Canyon 

Channel 

San Diego 

Creek/Barranca 

Delhi Channel 

San Diego 

Creek/Michelson 

San Diego 

Creek/Michelson 

Peters Canyon 

Channel 

San Diego 

Creek/Michelson 

San Diego 

Creek/Michelson 

Peters Canyon 

Channel 

Red Shiner 6/9/98 

Red Shiner 6/9/98 

Red Shiner 6/9/98 

Striped Mullet 6/9/98 

Red Shiner 6/19/97 

Red Shiner 6/19/97 

Red Shiner 6/19/97 

Red Shiner 6/19/97 

Red Shiner 6/18/97 

Red Shiner 11/6/96 

Red Shiner 11/6/96 

Red Shiner 11/6/96 

Red Shiner 6/17/95 

Red Shiner 6/17/95 

Red Shiner 6/17/95 

Freshwater finfish results 

count 

max 

mean 

median 

4% 10% 

0.344 0.014 0.034 

0.116 0.005 0.012 

0.200 0.008 0.020 

0.882 0.035 0.088 

0.134 0.005 0.013 

0.057 0.002 0.006 

0.063 0.003 0.006 

0.148 0.006 0.015 

0.085 0.003 0.009 

0.06 0.002 0.006 

0.07 0.003 0.007 

0.15 0.006 0.015 

0.150 0.006 0.015 

0.170 0.007 0.017 

0.090 0.004 0.009 

15 

0.88 0.04 0.09 

0.18 0.01 0.02 

0.13 0.01 0.01 

summary document 88