G. Fred Lee, PhD, PE, DEE
G. Fred Lee & Associates
El Macero, CA

and

Scott Taylor, PE
Robert Bein, William Frost Associates
Irvine, CA

June 1997

As part of an upper Newport Bay watershed-based water quality evaluation and management program a review of existing information on the water quality characteristics of Upper Newport Bay has been conducted. A summary of the findings is presented below.

Previous studies (conducted in late 1992 and early 1993) on San Diego Creek waters as they enter Upper Newport Bay show that aquatic life toxicity was measured in the Creek waters. These studies were limited to two samples, where the cause of this toxicity was not identified. Further, chemical analysis of tributary waters and Bay waters has shown that the concentrations of some heavy metals with potential to cause aquatic life toxicity, were present in excess of United States Environmental Protection Agency (U.S. EPA) water quality criteria. There is, therefore, a potential that these exceedances of the water quality criteria may represent toxic conditions to aquatic life in the waters where they occur. Further studies are needed to determine whether San Diego Creek waters entering Upper Newport Bay are toxic to aquatic life. If toxicity in the Creek waters is found, then the significance of this toxicity to aquatic life within San Diego Creek and Upper Newport Bay should be evaluated. If toxicity is judged to be significant with respect to potentially impairing the beneficial uses of Upper Newport Bay and/or San Diego Creek waters, then the cause of this toxicity and the sources of the constituents that cause the toxicity should be identified and, if possible, controlled at the source.

Monitoring San Diego Creek as it enters Upper Newport Bay shows that at least part of the chlorinated hydrocarbon pesticides and PCBs present in Upper Newport Bay aquatic life may be derived from the input of these chemicals to the Bay via San Diego Creek. Further studies need to be done to determine if this is, in fact, the situation today. If it is, then forensic studies should be done to determine if there are specific sources of these chemicals within the San Diego Creek watershed that can be controlled to reduce the excessive bioaccumulation of hazardous chemicals that is occurring in San Diego Creek and Upper Newport Bay aquatic life.

There is need for additional monitoring of fish from Upper Newport Bay and Lower San Diego Creek to establish the current levels of fish tissue contamination relative to those that are potentially hazardous for use of the fish as food. There is also need to better understand whether there is significant use of San Diego Creek fish as human food. Because of the limited water in San Diego Creek during much of the year and the limited size of the fish normally present in the Creek, it is likely that there is limited human health threat associated with eating fish from the Creek even if they contain excessive concentrations of chlorinated hydrocarbon pesticides, PCBs, and mercury. There may, however, be a potential wildlife threat, especially to fish-eating birds due to the excessive concentrations of the chlorinated hydrocarbon pesticides, PCBs, and mercury that could be present in San Diego Creek fish. There is no information at this time on whether dioxins are present in Upper Newport Bay and San Diego Creek fish tissue at excessive concentrations for the use of fish as human food. Since problems of this type are being found in many waterbodies, the concentrations of dioxins in fish taken from Upper Newport Bay and San Diego Creek should be examined.

No information is available on whether aquatic life within Upper Newport Bay and its tributaries are experiencing disease due to pathogenic organisms, carcinogens, or other chemicals that cause tumors and/or other abnormal tissue growth. Also, no information is available as to whether there are any endocrine active or other substances that impair Upper Newport Bay aquatic organisms and water fowl reproduction/behavior. This is an emerging area of increasing national/international water quality concern that could be significant in Upper Newport Bay. However, based on what is known from other areas, this is not likely a significant problem for aquatic life in Upper Newport Bay. Generally, where these problems have been found elsewhere, they are associated with major industrial wastewater inputs. There may be, however, problems of this type associated with past and possibly current pesticide/herbicide inputs to the Bay. The current pesticide/herbicide registration process used by the U.S. EPA does not adequately evaluate the potential for these types of chemicals to be adverse to aquatic life and wildlife.

The 1994 Water Resources Control Board-U.S. EPA EMAP/BPTCP studies have shown that the sediments of Upper Newport Bay are, at some locations, toxic to some forms of aquatic life. The cause of this toxicity has not been identified. Further, its significance in impairing the designated beneficial uses of Upper Newport Bay and associated waters is unknown. There is need to evaluate whether the toxicity found is of potential significance to Upper Newport Bay water quality. If it is judged significant, toxicity investigation evaluation (TIE) studies need to be conducted to try to determine the constituents responsible for the sediment toxicity and, through forensic studies, their sources.

Some attention has been given in previous studies to the chemical characteristics of Upper Newport Bay sediments. However, while Upper Newport Bay sediments, at some locations, contain elevated concentrations of heavy metals and some other constituents, it is not possible, from the information available, to determine whether these elevated concentrations are responsible for the aquatic life toxicity found in the sediments. It is well established that there is no relationship between the concentration of a constituent in sediments and its potential impact on sediments/water quality. There are a wide variety of constituents in aquatic sediments such as sulfides, organic carbon, carbonates, and hydrous metal oxides that detoxify heavy metals and other constituents, rendering them inert. Site-specific TIEs need to be conducted to determine the cause of the toxicity and the potential role, if any, that elevated heavy metals, pesticides, etc., contribute to this toxicity.

Upper Newport Bay is experiencing excessive fertilization due to the input of aquatic plant nutrients (nitrogen and phosphorus compounds). Excessive fertilization is significantly impairing the beneficial uses of the Bay. It is manifested primarily as attached algal growth that appears in excessive amounts in mid-spring and lasts through early fall. It appears that nitrogen compounds (nitrate, nitrite, and ammonia, as well as the part of the organic nitrogen that converts to ammonia/nitrate) are the key chemicals potentially limiting further algal growth within the Bay. The concentrations of available forms of phosphorus in Bay waters, at times, may become sufficiently low to also limit algal growth in the Bay. Information available indicates that for most of the year, the current nitrate and other nitrogen compounds input to the Bay through San Diego Creek as well as from other tributaries and local urban area street runoff and from possible groundwater input to the Bay are surplus for that needed to support the algal growth occurring in Bay waters. If this is the case, then the maximum degree of excessive fertilization of Upper Newport Bay waters is not now controlled by nitrogen input to the Bay. Further work needs to be done to examine this situation.

The information available shows that much of the nitrogen load to the Bay over the year has little or no influence on the excessive fertilization of the Bay because of the short residence time of tributary waters and their associated nitrogen loads in the Bay. The nitrogen compounds added during late fall, winter, and early spring do not generally cause excessive fertilization problems. They are flushed through the Bay before the excessive fertilization water quality problems begin in mid-spring.

An area that has not yet been adequately investigated is the role of the high nitrate (30 to 70 mg/L NO₃^--N) in the surficial groundwaters that enter San Diego Creek and its tributaries as well as possibly directly through subsurface flow into Upper Newport Bay as a source of nitrogen that is contributing to the excessive fertilization of Upper Newport Bay. It is unknown if the Wetlands Water Supply Project being conducted by the Irvine Ranch Water District (IRWD), where part of the San Diego Creek waters that enter the Bay are passed through a wetlands area for nitrate removal (denitrification), will significantly change the current situation relative to excessive algal growth to the point where the public would perceive a significant improvement in Bay water quality.

There is need to better understand nutrient (nitrogen and phosphorus) dynamics (aquatic chemistry), nutrient sources, and the factors controlling the excessive fertilization of Upper Newport Bay waters with particular reference to the amount of nitrogen and/or phosphorus inputs to the Bay during the critical periods of the year that lead to the excessive fertilization problems-use impairments, in order to explore the development of nutrient-control programs that will effectively control the eutrophication-related use impairments of Upper Newport Bay waters.

It appears that there may be dissolved oxygen depletion problems in Upper Newport Bay associated with the excessive fertilization of the Bay. Further studies need to be done to be certain the excessive fertilization of Bay waters does not lead to low dissolved oxygen problems as part of the diel (night/day) changes in DO that occur in highly eutrophic waters.

Litter is a significant cause of water quality deterioration-beneficial use impairment of Upper Newport Bay. The Orange County Public Facilities and Resources Department (OCPFRD) is initiating litter control programs that should reduce litter accumulation in the Bay. Further, Caltrans has extensive litter control programs (Adopt-A-Highway) in place on the facilities they operate.

No oil and grease accumulation problems have been identified in Upper Newport Bay. Examination of the Bay for oil and grease accumulation problems should be specifically conducted. If such problems are found, then the sources of the oil and grease that are accumulating in the area of concern should be identified through forensic studies and programs initiated to control the oil and grease at or near their source.

There is need to better understand the current sources of human and animal fecal pathogenic indicator organisms such as total and fecal coliforms, fecal streptococci, and other bacteria, as well as pathogens such as Cryptosporidium and selected enteroviruses for Bay waters in order to determine if it will be possible to improve the sanitary quality of Upper Newport Bay and, thereby, reduce the incidence of disease that could occur associated with contact recreation in the Bay.

Upper Newport Bay contains excessive sediment due to erosion from its watershed. This sediment accumulation causes shoaling (reduction of water depth), which interferes with navigation. It also changes the depth of the Bay water and thereby alters the aquatic plant habitat so that macrophytes encroach into the open water areas. Extensive studies have been conducted on the sources of the erosional sediment, and programs have been implemented to control the erosion at the source as well as through trapping before San Diego Creek water enters Upper Newport Bay. The Orange County Public Facilities and Resources Department (OCPFRD) has an ongoing evaluation of sediment control program effectiveness, and makes changes in the program as funds are available.

Impairment of Domestic Water Supply Water Quality

Since Upper Newport Bay is marine, it is not a domestic water supply source. While San Diego Creek and its tributaries are freshwater and could, at some locations, recharge groundwaters, the groundwaters in some areas of the San Diego Creek watershed are polluted by past agricultural and industrial/military activities leading to high total dissolved solids (TDS), nitrate, and, in some areas, chlorinated solvents. It does not appear, however, that the groundwater chlorinated solvent problems in the watershed are adverse to the beneficial uses of San Diego Creek or Upper Newport Bay.

It is not clear whether the poor water quality of San Diego Creek (due to groundwater discharge to the creek, with elevated TDS and nitrate) is polluting groundwaters in other areas due to creek and tributary recharge of the groundwater system. The shallow aquifer in the Irvine sub-basin contains high levels of TDS and nitrate. It is also apparent, however, that there is little interaction between the shallow aquifer and the principal aquifer, which has relatively good water quality and is used for domestic and agricultural purposes. The shallow aquifer consists primarily of fine-grained floodplain deposits, including massive silts and clays with 1- to 10-foot-thick discontinuous lenses of sand and gravel. Vertical hydraulic conductivities of the clays/silts are less than 1 inch per year. Therefore, vertical movement of groundwater and subsequent recharge to the principal aquifer through the semiconfining layer between the aquifers may reasonably be considered of limited near-term significance.

Overall, Upper Newport Bay is experiencing significantly impaired water quality due to:

Because of lack of information on aquatic life toxicity in San Diego Creek as it enters Upper Newport Bay, the field studies conducted during July 1, 1996 through June 30, 1997 focused on determining whether aquatic life toxicity was present in San Diego Creek waters during stormwater runoff events. San Diego Creek was sampled at Campus Drive just above where the Creek enters Upper Newport Bay early during the first storm of the fall 1996 (October 30, 1996). About 2 weeks later, during which there had been no rainfall, another sample of San Diego Creek waters was taken at this location. Two days later, on November 21, 1996, a second storm occurred that was also sampled. Each of the sets of samples were shipped under ice via courier to the University of California Davis Aquatic Toxicology Laboratory, where they were received within 1 day of sampling.

The first and second stormwater runoff events had 8 to 10 toxic units of aquatic life toxicity to Ceriodaphnia, a zooplankter that is representative of organisms used as larval fish food. This means the San Diego Creek water at the time of sampling needed to be diluted to about eight-fold to achieve a non-toxic water over a 7-day period of Ceriodaphnia exposure. There was no toxicity to fathead minnow fish larvae or algae. Toxicity was restricted to the zooplankton Ceriodaphnia. There was no toxicity to Ceriodaphnia or to fathead minnow larvae in the base flow sample of San Diego Creek water taken under dry weather flow conditions between the two storms.

Measurable concentrations of carbaryl, malathion, pendimethalin, and simazine were also found in the second stormwater runoff. The concentrations of these pesticides/herbicides were less than what would be expected to cause toxicity to aquatic life. Malathion is an organophosphate pesticide that was primarily used in Orange County in 1995 for landscape maintenance on public rights of way, agricultural crops, and by nurseries. Pendimethalin is an herbicide that was used in Orange County in 1995 for landscape maintenance. Simazine, also a herbicide, was used in Orange County in 1995 primarily for weed control on rights of way, in nurseries, and in landscape maintenance. Carbaryl was used in 1995 in Orange County primarily for agricultural purposes.

From the characteristics of the toxicity found, it can be concluded that most of the toxicity present in the samples of San Diego Creek runoff water is due to unregulated or inadequately regulated organophosphate or carbamate pesticides. Neither the U.S. EPA nor the state of California has developed water quality criteria for diazinon and methomyl. The U.S. EPA has developed a water quality criterion for chlorpyrifos. The California Department of Fish and Game has developed suggested water quality criteria for diazinon, chlorpyrifos, and methomyl. These criteria, however, do not have official regulatory status. The criterion value for chlorpyrifos is similar to the U.S. EPA criterion. The concentrations of these pesticides found in the San Diego Creek stormwater runoff samples were above the suggested criterion values.

The studies conducted thus far have identified approximately 40 percent of the toxicants in the San Diego Creek stormwater runoff samples. There is need for additional toxicity investigation evaluations (TIE) to determine what other constituents are a significant cause of toxicity in the San Diego Creek stormwater runoff samples. Limited work on this issue is considered for subsequent phases of the Evaluation Monitoring Program.

The Evaluation Monitoring Program will also, during its final phases in cooperation with the regulatory agencies and stormwater managers, develop guidance on how a watershed-based water quality management program can use the results of an Evaluation Monitoring Program to formulate new technically valid, cost-effective BMPs for control of water quality use impairments in the receiving waters of the stormwater runoff. The focus of these BMPs will, based on the nature of the toxicants responsible for the toxicity found thus far, be on control of their use at the source in order to minimize, if not eliminate, their transport in stormwater runoff.

Overall Evaluation Monitoring Program Accomplishments and Progress

The Evaluation Monitoring Program was established to show that an alternative approach to conventional stormwater runoff monitoring and BMP development could be initiated that more reliably assesses the real water quality problems-use impairments caused by stormwater runoff associated constituents in the receiving waters for the runoff. The value of the Evaluation Monitoring Program has been demonstrated during Phase 1 of the Program. While conventional monitoring programs have shown that some heavy metals and other constituents are present in stormwater runoff to the Bay at concentrations above U.S. EPA water quality criteria, these programs have not determined, for potentially toxic constituents, such as the heavy metals, whether the exceedance of the criterion values results in aquatic life toxicity in the runoff and receiving waters.

The Evaluation Monitoring Program has defined, through a review of the data and the literature pertinent to Upper Newport Bay water quality issues, many issues that need to be further examined as part of a comprehensive evaluation of the impact of chemical constituents in stormwater runoff on Upper Newport Bay waters. For example, one of the heavy metals that has not been measured to date is mercury. Mercury has been found to be a constituent in stormwater runoff. Mercury is of concern because of its high potential to bioaccumulate in fish tissue, rendering the fish unsafe for use as food.

A similar situation exists with respect to the measurement of chlorinated hydrocarbon pesticides. While the concentrations of various chlorinated hydrocarbons in runoff waters and in Bay waters have been measured as part of a conventional stormwater runoff monitoring program, the data generated from these programs has not revealed whether the constituents are present in forms that can be adverse to the beneficial uses of Upper Newport Bay. The Evaluation Monitoring approach, however, directly assesses whether mercury or the chlorinated hydrocarbons measured in runoff or in Bay waters bioaccumulate to a sufficient extent in aquatic organism tissue to cause a real water quality-use impairment problem.

Basically, the conventional stormwater runoff monitoring approach and its associated receiving water monitoring focus on determining concentrations of chemical constituents that could, under some conditions, cause water quality problems. The conventional monitoring approach, however, fails to address the unregulated or under-regulated chemical constituents in stormwater runoff. In the conventional monitoring approach, it is necessary to try to extrapolate from the concentrations of a constituent found in runoff or receiving waters to estimate water quality problems of concern to the public in the receiving waters from the runoff. This extrapolation, however, is, at best, tenuous in that it requires a high degree of understanding of the relationship between the concentrations of a constituent found in runoff waters or receiving waters to whether the constituent is in toxic/available forms that could adversely impact the beneficial uses of a waterbody. This extrapolation requires detailed, usually with few exceptions, unavailable information on the aqueous environmental chemistry of the constituent (transport and chemical transformations-kinetics and thermodynamics) and its aquatic toxicology-toxicity or uptake as a function of duration of exposure.

The Evaluation Monitoring approach, on the other hand, directly addresses the issue of whether there is a real water quality problem due to toxic or bioaccumulatable constituents, identifies the cause of the toxicity, determines the sources, and develops technically valid, cost-effective control programs. A summary of the key components of the Evaluation Monitoring Program is presented in Figure 1. Such an approach allows for prioritization of water quality programs to focus on the most acute problems rather than giving all potential threats equal consideration. By more efficient use of resources it is possible to make measurable gains in water quality management more rapidly.

The Evaluation Monitoring Program, through its Phase 1 efforts, has proven to be valuable in defining the real water quality problems that need further attention in managing the impacts of stormwater runoff from the Upper Newport Bay watershed. The subsequent phases of this Program will provide additional information needed to formulate technically valid, cost-effective stormwater runoff water quality management programs for Upper Newport Bay. This Program has also served as a foundation for acquisition of U.S. EPA funding that enables the Santa Ana Regional Water Quality Control Board and the Public Facilities and Resources Department to expand their water pollution control efforts to control real toxicants in the stormwater runoff to Upper Newport Bay.

Upper Newport Bay Water Quality Characteristics

Watershed Characteristics

The primary tributary of Upper Newport Bay is San Diego Creek. The San Diego Creek watershed is bounded on the north by the Santiago Hills (Loma Ridge) and to the south by the San Joaquin Hills. The major portion of the basin is comprised of the Tustin Plain, a broad alluvial valley occupying the central portion of the watershed. Figure 2 indicates the general features of the watershed with respect to San Diego Creek and Upper Newport Bay. The watershed has been greatly altered due to development. Most of the existing channel features were constructed in the early part of this century to accommodate farming. During the 1960s, easements for many of the principal streams were granted to the Orange County Flood Control District, and interim improvements were made to many of the channels.

The Newport Bay watershed includes an area of about 154 square miles. The San Diego Creek watershed contains about 119 square miles with a mix of residential, commercial, industrial, recreational, and open space land uses. Other major tributaries of Upper Newport Bay include the Santa Ana Delhi Channel with a watershed of about 17 square miles, Big Canyon Wash with a watershed of about 2 square miles, and 16 square miles from other smaller tributaries. The Santa Ana Delhi Channel watershed includes commercial, industrial, recreational, and residential land uses, with commercial and industrial land uses predominant. The Big Canyon Wash watershed is comprised of commercial, recreational, open space, and residential land uses, with residential uses predominant. The remaining area is comprised of commercial and residential uses.

The San Diego Creek portion of the Upper Newport Bay watershed (119 square miles) encompasses elevations that range from a high in the Santiago Hills of 1,775 feet to sea level at Upper Newport Bay. A large portion of the Tustin Plain generally has slopes of less than 1 percent, with steeper slopes occurring near the foothills. Existing land uses in the watershed include agricultural, open space, residential, commercial, industrial, and recreational. In general, the foothill areas remain as open space, with development generally occurring in the Tustin Plain along the western and eastern watershed boundaries and to the south. The central portion of the watershed retains the most agriculture, although this area is undergoing urbanization at a rapid pace. Table 1 summarizes the general land uses within the watershed.

It is estimated that less than 40 percent of the developed Upper Newport Bay watershed is impervious surface. The developed area represents about 50 percent of the total watershed area. Tettemer and Associates (1989) indicated that Orange County has estimated that the ultimate impervious surface in the watershed will be about 60 percent. Urbanization and improvement of the channel system have decreased the watershed runoff lag time, increased the peak discharge as compared to pre-development conditions, and enhanced the ability of the watershed and San Diego Creek to transport chemical constituents and sediment to Upper Newport Bay.

  Table 2 provides tributary drainage areas and flow rates at locations coincident or near the stormwater runoff sampling point (Campus Drive) described in this report. The drainage area at each point represents the total watershed area that drains to the specified location. The Culver Drive location is where stormwater runoff information presented in this report is collected. Two discharge frequency values are provided in the table, Q₁₀₀ and Q_2. The value for Q₁₀₀ represents the discharge at the point indicated for a storm with a hypothetical return period of once every 100 years. A storm of this magnitude has a 1 percent chance of occurring in any given year. A 100-year return frequency represents the design return period used for San Diego Creek flood control improvements.

The Upper Bay is characterized by a semidiurnal tidal pattern of two unequal highs and lows occurring each day. The maximum tidal range is about 9 feet (+7.2 ft MLLW to -1.8 ft MLLW), with little difference in absolute magnitude between the upper and lower Bays. Mudflats comprise the lower portion of the littoral zone below about 3.0 MLLW and are subject to daily inundation. Salt marsh occupies the mid and upper littoral zones up to the extreme high water (EHW) elevation. The salinity in the Upper Bay in 1959 was close to seawater (Gerstenberg, undated). The Bay is becoming progressively more estuarine in character as freshwater inputs to the Bay increase.

Presented below is a summary of information that is currently available on the water quality characteristics of Upper Newport Bay

Aquatic Life Toxicity

One area of greatest concern regarding chemical effects on the aquatic life resources of a waterbody is toxicity. Prior to 1970 the primary concern was toxicity that killed adult fish as evidenced when large numbers of dead fish accumulate along the shore. With the advent of effective water pollution control programs in the 1960s, the acute toxicity to adult fish resulting in major fish kills has been largely controlled. Today, while there are exceptions to this situation, they are normally rare.

In the 1970s the emphasis for water pollution control of toxics shifted from acute toxicity to adult fish to acute toxicity to larval fish and fish food such as zooplankton as well as chronic toxicity to larval fish and zooplankton. Both acute and chronic toxicity to small forms of aquatic life are often difficult to detect since there are no readily discernible fish kills. However, the impacts of acute toxicity to small forms of aquatic life that kills the organisms as well as chronic toxicity which, while not killing them, alters reproduction, growth rates, etc., can be important in impairing the aquatic life-related beneficial uses of a waterbody.

Beginning in the late 1960s, the U.S. EPA and its predecessor agencies as well as other agencies began to develop laboratory-based aquatic toxicity tests to determine whether a particular wastewater discharge or stormwater runoff to a waterbody could potentially cause aquatic life toxicity in the waterbody. The first of these tests was the 96 hr LC₅₀ in which fish or zooplankton are placed in a test vessel (a beaker or aquarium) that contains the effluent/runoff water or ambient waters. In a parallel test, the same organisms are exposed to a reference water that does not contain the potentially toxic substances. The number of test organisms that die (lethal concentration) during a 4-day (96-hour) period is determined. While this approach has been developed into a reliable test for acute toxicity, it does not address the issue of chronic toxicity.

Typically the chronic toxicity of chemicals occurs at a factor of 10 to 100 times lower concentrations than acute toxicity (i.e., the acute/chronic ratio is 0.1 to 0.01). For example, if copper is acutely toxic to fish at 100 µg/L, it is likely chronically toxic to fish at about 10 µg/L. In the 1980s, the U.S. EPA and others developed short-term chronic toxicity test procedures in which larval forms of organisms are exposed to potentially toxic waters for a period of several days to a week. These tests typically use larval forms of fathead minnows and a zooplankton, Ceriodaphnia, as test organisms. There is also some testing done with algae, although the algal testing procedures and interpretation of the results involve significantly different approaches than for larval fish and zooplankton. The interpretation and use of planktonic algal toxicity tests in water quality evaluations have been reviewed by Lee and Jones-Lee (1996a). They caution against the strict interpretation of the results of these tests as typically conducted in evaluating a water quality-use impairment for toxicity tests involving fish and zooplankton.

Beginning in the mid-1970s several programs were initiated to determine the presence of toxic chemicals, such as heavy metals and pesticides, in Upper and Lower Newport Bay and its tributaries. According to SARWQCB (1995a), the last time that data of this type were compiled was in 1987. The late-1980 data review that was published by Blodgett (1989) is sufficiently dated so as to not necessarily provide a reliable indication of the present conditions within Upper Newport Bay or its tributaries such as San Diego Creek. From the information available in the late-1980s (associated with the Blodgett review), it appears that a number of the most severe contamination problems associated with Upper and Lower Newport Bay reported in the 1970s and the 1980s have been decreasing, indicating that the water quality programs initiated in the 1980s were effective in beginning to control the potentially toxic chemical constituent input to Newport Bay.

One of the conclusions of the Blodgett (1989) report was that there was need for follow-up studies on the sources and significance of toxic chemicals found in Upper Newport Bay water and organisms. Beginning in the fall of 1992, Olson and Martinez (1993) conducted a study of water quality in Upper and Lower Newport Bays and their tributary channels. This study examined the Upper and Lower Newport Bays' water quality monitoring data over the last 10 years for elevated concentrations of heavy metals and pesticides where a comparison was made between the ambient water concentrations and U.S. EPA water quality criteria. Also, two sets of water and sediment samples (October 1992 and January 1993) were collected and analyzed. One sample set was analyzed for a suite of heavy metals, several organochlorine pesticides, and PCBs. The second set of samples was analyzed for organophosphate pesticides.

It was reported that boatyards located in Lower Newport Bay were apparently a source of high levels of copper present in Bay waters. Further, Olson and Martinez (1993) indicated that there was a potential for copper present in the Lower Bay to be transported to the Upper Bay due to tidal transport. Upper Newport Bay has a 1- to 2-meter tidal cycle, which could account for significant between-bay transport of chemical constituents.

Lead was found at the water quality objective concentrations in the Santa Ana-Delhi Channel runoff waters. Excessive concentrations of heavy metals were primarily located in the Lower Bay. Occasionally, some elevated concentrations of metals were found in Upper Bay and Upper Bay tributary waters.

The five organochlorine pesticides (DDT, endosulfan, dieldrin, endrin, and heptachlor) were present in runoff waters to Upper Newport Bay at concentrations exceeding water quality objectives. Diazinon was present in all four runoff samples tested. PCBs were detected only in sediments in the Lower Bay.

The approach that has been used to date for assessing whether there are toxic substances and potential toxicity to aquatic life in a waterbody has been to measure the concentrations of potentially toxic constituents in the waterbody at various times of the year. The Santa Ana Regional Water Quality Control Board in the Blodgett (1989) report showed that there are a number of chemical constituents such as heavy metals and some organics such as pesticides present in Upper Newport Bay as well as tributary waters at concentrations that are potentially toxic to aquatic life. Olson and Martinez (1993) updated the information on the presence of heavy metals and other potentially toxic constituents in San Diego Creek and Upper Newport Bay waters. They indicated that as of the early 1990s, there were still potentially significant concentrations of some potentially toxic constituents in these waters.

SARWQCB (1995a) stated that there are excessive trace metals and organics in San Diego Creek and at certain locations in the Bay. Urban stormwater runoff is specifically mentioned a source of potentially toxic substances. SARWQCB states that additional efforts should focus on more specific identification of toxic compounds.

Recently, as part of the development of the IRWD's Wetlands Water Supply Project, CH2M HILL (1996) has reported on the aquatic life resources of San Diego Creek just upstream of Upper Newport Bay. In this region, it was found (MBC, 1995) that San Diego Creek has a number of freshwater fish, including carp, chubs, and shiners. Evidently, these fish are reproducing in San Diego Creek or its tributaries. This indicates that San Diego Creek is not highly toxic to fish.

Bailey et al. (1993) conducted toxicity tests on San Diego Creek and several other tributaries of Upper Newport Bay. These tests used larval fathead minnow, fish; Ceriodaphnia dubia, zooplankton; and Selenastrum capriocornutum, alga. These samples were collected between November 1992 and January 1993. All samples were collected within 12 to 24 hours of a rainfall event and processed at the University of California Davis Aquatic Toxicology Laboratory. The sampling stations included San Diego Creek at Campus Drive, Santa Ana-Delhi Channel at Irvine Avenue, San Diego Creek at Culver Drive, and Peters Canyon Channel at Barranca Highway. Peters Canyon Channel is a tributary of San Diego Creek. Santa Ana-Delhi Channel is a major stormwater runoff tributary of Upper Newport Bay that primarily drains urban and industrial/commercial areas.

Except for one sample from the Santa Ana-Delhi Channel, all samples showed no significant toxicity compared to the controls for the fathead minnows. However, the tests conducted with Ceriodaphnia for San Diego Creek (Campus Drive), the Santa Ana-Delhi Channel, and San Diego Creek (Culver Drive) all caused complete mortality of the test organism. The sample from Peters Canyon Channel showed no toxicity based on death of the organism in the first set of samples. However, in the second set of samples, there was 100 percent mortality at this location. The testing with the alga Selenastrum showed no inhibition of algal growth, which indicates the waters did not contain constituents at the time of sampling that would inhibit algal growth.

As part of the Olson and Martinez (1993) studies, chemical testing of stormwater runoff found diazinon, a pesticide, and diuron, a herbicide, at potentially significant concentrations. The work did not confirm whether the toxicity found was due to these chemicals or if these chemicals were present in sufficient concentrations to be potentially toxic.

Diuron is a herbicide that is used on highway right of ways. However, it is unknown whether it was being used in the Upper Newport Bay Watershed on highway right of ways at the time of the studies in late 1992 and early 1993. In 1990 over 1,300 pounds of diuron were applied to right of ways in Orange County. Also, over 1,200 pounds were applied in the county for structural pest control (Department of Pesticide Regulation [DPR], 1994). Powell and Leyva (1994) found toxic concentrations of the herbicide diuron associated with its use on highway right of ways. These studies were not conducted in the Orange County area.

Previous studies conclude that there were toxicants to zooplankton - Ceriodaphnia in stormwater runoff in several of the major tributaries of Upper Newport Bay in 1992-93. However, the chemical(s) responsible for this toxicity was not identified.

Studies conducted by the Central Valley Regional Water Quality Control Board staff and the USGS Sacramento Office as well as others (Domagaiski, 1995; Kuivila, 1993; Kuivila and Foe, 1995; Connor, 1995; Foe, 1995a,b; USGS, 1993; Cooper, 1996; Hansen & Associates, 1995; Katznelson and Mumley et. al., 1997; Waller et. al., 1995; Bailey et. al., 1996; McConnell et. al., 1997) have found that stormwater runoff from urban and rural areas contains organophosphate pesticides that are acutely toxic to Ceriodaphnia. Because Ceriodaphnia toxicity was previously found in San Diego Creek waters by Bailey et. al. (1993), and because diazinon has been reported to be present in San Diego Creek waters (Olsen and Martinez,(1993), there is need to determine whether the previously reported toxicity to this organism is still occurring today in tributaries of Upper Newport Bay. If toxicity is found in Upper Newport Bay tributary waters, then studies are needed to determine its cause and significance in potentially adversely affecting the beneficial uses of Upper Newport Bay as well as San Diego Creek. This issue has been addressed as part of the Phase I field monitoring activities presented in the report by Lee and Taylor (1997).

The traditional approach for assessing a potential aquatic life toxicity in a waterbody is to measure the concentrations of a suite of potentially toxic chemicals for which the U.S. EPA has developed water quality criteria. The previous reviews, Blodgett (1989), Olson and Martinez (1993), and the SARWQCB (1995a), have all reported excessive concentrations of some heavy metals and other constituents in Upper Newport Bay and San Diego Creek waters relative to U.S. EPA water quality criteria. Considerable additional data has been collected by OCEMA now Orange County Public Facilities and Resources Department in their stormwater monitoring of San Diego Creek and other tributaries of Upper Newport Bay as well as Bay waters since the last comprehensive review of the data on the chemical concentrations of potentially toxic constituents such as heavy metals was conducted in the early 1990s by Olson and Martinez. It is, therefore, appropriate to review the more recent monitoring data on tributary and Bay waters to determine if there are potentially excessive concentrations of heavy metals and other constituents that could, if they are in toxic-available forms for a sufficient period of time, cause aquatic life toxicity to San Diego Creek and/or Upper Newport Bay aquatic life.

OCPFRD is a co-permittee with the 31 municipalities in Orange County for the NPDES stormwater permit covering urban area stormwater runoff water quality management. OCEMA has been conducting a stormwater runoff monitoring program as part of this permit since May 1991. OCPFRD operates a network of monitoring stations located throughout the county, which includes San Diego Creek and its tributaries as well as at various locations within Upper Newport Bay. Two reports have been issued by OCEMA that present the data obtained in their stormwater runoff monitoring. OCEMA (1994) presents the data for the period 1991 through the spring of 1994. The data collected after this time through the spring of 1996 is presented in OCEMA (1996).

OCPFRD's monitoring includes measurement of flow, various physical parameters, electrical conductivity, turbidity, pH, nitrate, ammonia, total kjeldahl nitrogen, phosphate, total suspended solids, volatile suspended solids, cadmium, chromium, copper, lead, nickel, silver, zinc, and hardness in the water column. Some of the heavy metal measurements in the water column included filtering the sample before analysis to determine the dissolved metals. Also, determinations have been made of the same heavy metals, DDD, DDE, DDT, gamma BHC, 2,4-D, 2,4,5-TP, silvex, benzo(k) fluoroanthene, and pyrene in the Newport Bay and the Santa Ana River watershed sediments. The primary thrust of the OCPFRD stormwater runoff monitoring program is the assessment of the concentrations of potentially toxic constituents.

A review of this database shows that the tributaries of Upper Newport Bay contain sufficient concentrations of nitrate, copper, and zinc to potentially be adverse to water quality in the tributaries as well as within Upper Newport Bay. Upper Newport Bay, near where San Diego Creek enters it, was found to contain total copper, lead, nickel, silver, and zinc concentrations above U.S. EPA water quality criteria. DDT and its breakdown products DDD and DDE were found in Upper Newport Bay tributary waters and within the Bay at concentrations that could lead to excessive bioaccumulation within aquatic life. Polyaromatic hydrocarbons (benzo(k) fluoroanthene and pyrene) and several heavy metals were found in Newport Bay sediments at elevated concentrations.

The stormwater runoff monitoring data currently available focuses on determining selected chemical constituent concentrations in runoff waters and to some extent in receiving waters and their sediments. While a number of the chemical constituents are found at concentrations above U.S. EPA water quality criteria or former state water quality objectives, that in general are numerically equal to the U.S. EPA criteria, this exceedance of the regulatory objectives cannot be used to determine whether real water quality-use impairments are occurring.

The constituents present at elevated concentrations relative to water quality criteria/objectives are likely present to some and possibly substantial extent in non-toxic, non-available forms, with the result that while there could be an "administrative" exceedance of a water quality criterion/objective, this exceedance may not be reflective of real water quality problems that would impair the use of the tributaries or the Bay waters by the public. For example, many of the heavy metals monitored are of concern because of their potential to cause aquatic life toxicity. However, it is not possible to relate the concentration of total or dissolved metals as measured in the available data to actual aquatic life toxicity in the waterbody in which the metals are present. It is for this reason that ambient water toxicity measurements of the type described in the Evaluation Monitoring Program developed by Silverado (1997) focus on measurement of aquatic life toxicity to directly assess whether measured as well as unmeasured constituents are responsible for potential water quality-use impairments in the tributaries to Upper Newport Bay as well as in the Bay waters. This issue is discussed further by Lee and Taylor (1997).

Currently sediment monitoring data has provided information on the total concentrations of a variety of metals and other constituents in Upper Newport Bay and other waterbody sediments. The data, however, cannot be used to assess whether constituents in the sediments are in toxic/available forms and whether the measured as well as the unmeasured constituents in the sediments are adversely impacting the beneficial uses of the waterbody in which the sediments are located. Again, as with water column measurements, it is not possible to determine from chemical concentrations of constituents in sediments whether elevated concentrations of heavy metals, polyaromatic hydrocarbons (PAHs), chlorinated hydrocarbon pesticides, etc., are in toxic/available forms that could be adverse to the numbers, types, and characteristics of desirable forms of aquatic life in the waterbodies in which the sediments are located. This issue has been reviewed by Silverado (1997) as part of developing the Evaluation Monitoring Program and this Demonstration Project.

Elevated concentrations of potentially toxic constituents, such as heavy metals, in a tributary's stormwater runoff waters do not necessarily translate to excessive concentrations in the receiving waters for the runoff. There are a wide variety of physical, chemical, and biological factors that must be evaluated to determine whether the constituents in the runoff waters are toxic to the aquatic life. Significantly elevated concentrations of a variety of the constituents of concern can be present in stormwater runoff from urban areas and highways without adversely impacting the beneficial uses of the waterbody.

As discussed by Lee and Jones-Lee (1997a), increasing recognition is being given to the potential significance of chromium VI as a toxicant to certain forms of aquatic life, especially zooplankton. The Environment Canada (1995) reporting of the toxicity of chromium VI to some forms of zooplankton (Ceriodaphnia reticulata) at 0.5 µg/L raises concern about the impact of urban area stormwater runoff as a source of chromium that can be toxic to some forms of aquatic life. Mount (1997) has indicated that the toxicity of chromium VI to Ceriodaphnia dubia occurs at less than the U.S. EPA water quality criterion of 10 µg/L. Pitt and Field (1990), as reported by Lee and Jones (1991a), found that the median concentration of total chromium in urban stormwater runoff obtained during the U.S. EPA National Urban Runoff Program (NURP) studies was 30 µg/L.

The mean concentration of soluble total chromium in stormwater runoff from urban area streets across the U.S. was 1.3 µg/L. While no information is available on whether this chromium was in a chromium III or VI form, since it was soluble and since chromium III tends to strongly sorb to particulates, it is possible that chromium VI occurs in urban area stormwater runoff at a concentration that could be toxic to some Ceriodaphnia and other zooplankton species. It is also possible that some of the toxicity that is now attributed to organophosphate pesticides in urban area stormwater runoff that is particularly significant to Ceriodaphnia could be due to chromium VI. This is an area that needs further attention.

While there have been extensive measurements of the concentrations of a variety of potentially toxic chemical constituents in Upper Newport Bay tributaries and Bay waters, these studies have not yielded definitive information as to whether water quality-use impairments have in the past or are now occurring due to toxic chemicals. There is need to conduct further studies to determine whether San Diego Creek waters entering Upper Newport Bay are toxic to aquatic life. If toxicity in the Creek waters is found, then an evaluation should be conducted on the significance of this toxicity to aquatic life within San Diego Creek and Upper Newport Bay. If toxicity that is judged to be significant with respect to potentially impairing the beneficial uses of Upper Newport Bay and/or San Diego Creek waters is found, then the cause of this toxicity and the sources of the constituents that cause the toxicity should be identified and, if possible, controlled at the source.

The bioaccumulation of hazardous chemicals in aquatic organism tissue is of concern since some of the bioaccumulated chemicals occur at sufficient concentrations in fish tissue to increase the risk of cancer or other adverse impacts to those who eat the fish. This has lead the Food and Drug Administration (FDA) to develop action levels to determine when fish contain excessive concentrations of hazardous chemicals in their edible tissue. The FDA action levels, however, incorporate a number of factors including economic considerations that tend, for some chemicals that bioaccumulate in fish tissue, to represent an increased risk of adverse impacts over that typically considered to be acceptable today. Several years ago it was somewhat arbitrarily determined that an acceptable increased cancer risk of one additional cancer in a million people exposed to the hazardous chemical for their lifetime was an "acceptable" risk. This value is commonly used today for determining whether drinking waters, aquatic organisms used as food, etc., contain sufficient concentrations of a hazardous chemical or groups of chemicals to represent a significant threat to public health.

The water quality criteria listed in the U.S. EPA (1987) "Gold Book" for bioaccumulatable chemicals were designed to prevent excessive bioaccumulation of hazardous chemicals that represent either an exceedance of FDA action levels in fish tissue or an increased cancer risk of one cancer in a million people who consume 6.5 g of fish per day (one meal per month) taken from the waters that contain the hazardous chemical of concern. More recently, the U.S. EPA has focused its effort for the control of hazardous chemicals that tend to bioaccumulate in fish on a risk-based approach (an increase in cancer risk). This is the approach that is widely used today for the chlorinated hydrocarbon pesticides (DDT, chlordane, etc.), PCBs, and dioxins. A similar approach is being used to establish water quality criteria for mercury. Mercury tends to bioaccumulate in fish tissue to levels that represent potential neurological damage to those who consume fish with elevated concentrations of mercury in their tissue. Recently, the U.S. EPA (1993a, 1994, 1995a) has released a series of guidance manuals devoted to bioaccumulation issues that serve as the background to the Agency's current approach for determination of excessive concentrations of hazardous chemicals in fish tissue. These manuals should be consulted for further background information on this matter.

One issue of concern regarding evaluating bioaccumulation data for the hazardous chemical content of fish and other aquatic life is the limited reliable information available to determine an excessive concentration of hazardous chemicals in fish with respect to the use of fish and other organisms food. However, it is now well-established that certain high molecular weight chlorinated hydrocarbons, such as DDT and PCBs, that tend to bioaccumulate in fish can cause reproductive impairment for fish-eating birds.

In estimating the critical concentrations of chlorinated hydrocarbons and certain heavy metals, such as mercury, in fish tissue that represent a hazard for human consumption, estimates have to be made regarding the amount of fish containing the hazardous chemicals that are consumed on a routine basis. Traditionally, the U.S. EPA has assumed that the average fish consumption rate in the U.S. is 6.5 g of fish per person per day (one meal per month). While that value may be appropriate for the average consumption, it does not protect those who eat local fish as a major component of their diet. In the San Francisco Bay region, the U.S. EPA has suggested that the average consumption rate of fish for some people in that region should be increased to 30 g per person per day (i.e., one meal per week).

In the discussions that follow devoted to the interpretation of the existing bioaccumulation data for fish from Upper Newport Bay and its tributaries, both fish consumption rates are considered. As discussed below, there are a number of chemicals where fish from Upper Newport Bay and its tributaries have tissue concentrations of hazardous chemicals of concern in the range between the values that result from the 30 g of fish per day and the 6.5 g of fish per day per person.

One issue that needs to be addressed for Upper Newport Bay water quality evaluation is to what extent people in the region eat fish from Upper Newport Bay tributaries. From the characteristics of the tributaries, such as San Diego Creek and its tributaries, it could be that there is no consumption of tributary water fish by humans, and, therefore, the human health aspects of bioaccumulation issues for Upper Newport Bay focus exclusively on fish from Upper Newport Bay and Newport Bay. However, wildlife that eat fish from San Diego Creek and its tributaries must be considered.

Some wildlife-based water quality criteria have been developed in the Great Lakes region (U.S. EPA, 1993b) to address excessive concentrations of hazardous chemicals in fish and other aquatic life that represent a threat to higher trophic level organisms that eat fish. However, there are questions as to whether the Great Lakes-based water quality criteria are appropriate for use in other areas. The Great Lakes have somewhat unique water quality characteristics compared to many waterbodies that, in general, would cause chemicals in the Great Lakes at particular concentrations in the waters to be more of a threat to the beneficial uses of a waterbody than occurs in most other waterbodies. This would be especially true in attempting to translate wildlife water quality criteria developed for the Great Lakes to Upper Newport Bay. Much higher concentrations of a potentially bioaccumulatable chemical can likely be present in Upper Newport Bay waters compared to Great Lakes waters without causing excessive bioaccumulation since there are a number of constituents in Upper Newport Bay waters that would tend to bind/reduce the availability of potentially bioaccumulatable chemicals compared to what commonly occurs in the Great Lakes.

The San Francisco Regional Water Quality Control Board, as part of the Bay Protection Toxic Cleanup Program data collection of the WRCB, has conducted a survey of the concentrations of various hazardous chemicals in San Francisco Bay fish. This survey resulted in a report presenting these results (SFRWQCB, 1995). To assess excessive concentrations of chlorinated hydrocarbons and mercury in fish tissue, the SFRWQCB has used several sets of tissue concentration screening values. One of these is the U.S. EPA guidance value based on a 30 g fish per person per day consumption rate. The other is based on the traditional 6.5 g of fish consumed per person per day. SFRWQCB also provided information on FDA action levels. These three screening levels are used in this study to examine whether fish taken from San Diego Creek and Upper Newport Bay contain concentrations of hazardous chemicals in their tissue to represent a potential public health threat to those who use the organisms as food. Except for PCBs, it is not possible to examine whether there are excessive concentrations of hazardous chemicals in fish that would represent a threat to wildlife since, at this time, the only wildlife-based criterion available is the U.S. EPA's Great Lakes' value for total PCBs.

The SFRWQCB (1995) also presented information on screening values based on so-called National Academy of Science (NAS) values as well as Maximum Tissue Residue Levels (MTRL) values. The "NAS" values have been used in California in an attempt to interpret data obtained in the state's Toxic Substances Monitoring (TSM) program. Several years ago the State Water Resources Control Board staff adopted the NAS values as a guide to determine excessive concentrations of chemicals in aquatic life tissue. These values were numeric concentrations that were suggested by the National Academy of Science and the National Academy of Engineering (NAE) in their 1972 Blue Book of water quality criteria. The chairman of the NAS/NAE (1973) Blue Book Criteria Committee (Fetterolf, 1996) who was also former chief biologist for the state of Michigan water pollution control program and former director of the Great Lakes Fisheries Commission, has indicated that it is inappropriate to use the 1972 "NAS" Blue Book values as being reliable today for estimating excessive concentrations of chemicals in aquatic life tissue. The U.S. EPA, any other state, and the National Academy of Science do not recognize the "NAS" values used by the SWRCB as reliable screening values for determining excessive concentrations of chemicals in aquatic organism tissue.

The MTRL values used by the SWRCB are also not reliable values for estimating concentrations of constituents in aquatic life tissue. These values are based on an extrapolation from water quality criteria and a standard bioaccumulation factor to estimate concentrations within fish tissue that would be adverse to the use of fish used as food. This approach, however, with few exceptions, overestimates the bioaccumulation that will occur because the bioaccumulation of a chemical depends upon the available forms of the constituent in the water column. The concentration of available forms is dependent upon site-specific characteristics with particular reference to those constituents that tend to cause bioaccumulatable chemicals to be unavailable for bioaccumulation. Applying standard bioaccumulation factors to Upper Newport Bay fish would be inappropriate since, in general, less bioaccumulation would be expected in Upper Newport Bay and its tributaries than occurs in many other waterbodies.

A number of the constituents measured in sediments as part of the OCPFRD stormwater runoff monitoring program, such as DDT, are of concern because of their potential to bioaccumulate in aquatic life to excessive levels, causing the aquatic life tissue to be hazardous for use as human food due to an increased cancer or public health risk. However, it is neither possible from either water column nor sediment concentration data to reliably predict whether the constituents reported in this data are in forms that can bioaccumulate within aquatic life tissues to excessive levels. As discussed elsewhere in this report, excessive bioaccumulation of some constituents in San Diego Creek and Upper Newport Bay aquatic life has been found in the past by the Water Resources Control Board's Toxic Substances Monitoring Program. Therefore, at least some of the potentially bioaccumulatable chemicals present in San Diego Creek and Upper Newport Bay waters/sediments are in available forms. The data, however, does not provide the information necessary to evaluate whether the potentially bioaccumulatable constituents measured at a particular location in the water column or sediments are responsible for the excessive bioaccumulation found in the past and is likely occurring today. To develop information necessary to determine whether the concentrations of potentially bioaccumulatable constituents in the water and/or sediments are present in forms that are significantly contributing to the bioaccumulation problem, if it still exists today, it is necessary to conduct special purpose studies like those described in the Evaluation Monitoring Program section of the ETC Runoff Management Plan (Silverado 1997) as well as Lee and Jones-Lee (1997b).

One type of chemicals of increasing concern because of excessive bioaccumulation in aquatic life tissue is dioxins. Dioxins are formed from combustion processes, including automobile exhaust, and they are present in vehicular traffic exhaust. They would, therefore, be expected to be ubiquitous in the environment. Recently the San Francisco Regional Water Quality Control Board released a report entitled, "A Survey of Stormwater Runoff for Dioxins in the San Francisco Bay Area" (SFRWQCB, 1997), which provides data on the dioxin content of urban area street and highway stormwater runoff. The concentrations of dioxins being found are a factor of 10 to 100 above U.S. EPA-proposed drinking water standards. While no information is provided on the water quality significance of the dioxins in the stormwater runoff, the fact that dioxins are being found at excessive levels in fish taken from various waterbodies, such as San Francisco Bay, is of concern. The San Francisco Regional Water Quality Control Board (SFRWQCB, 1995) has found that fish in San Francisco Bay have excessive levels of dioxins compared to U.S. EPA guidelines for protection of public health associated with consumption of fish containing dioxins.

Since dioxins tend to be strongly sorbed to particulates, it is likely that they are present in stormwater runoff in a particulate form. They are likely associated with small particulates and would not be effectively removed in detention basins. Further work needs to be done to evaluate this situation. No information is available at this time on the relative contributions of highway and street stormwater runoff as a source of dioxins compared to other sources. Ultimately, it will be appropriate for future studies beyond this Demonstration program to examine fish from San Diego Creek and Upper Newport Bay for excessive concentrations of dioxins to determine whether this is a potential problem in the Creek and Bay waters.

A constituent of potential concern in highway and urban area street runoff is lead. Lead concentrations in stormwater runoff frequently exceed U.S. EPA water quality criteria. Further, the concentrations of lead in soils and sediments near highways are often greatly elevated compared to soils from other areas. Lee and Jones-Lee (1992, 1997c) have reviewed the public health aspects of lead in soil and water. They point out that lead in both of these media tends to be over-regulated compared to current understanding of the impacts of lead on aquatic life and human health. One of the areas of particular concern is the potential for lead to bioaccumulate in aquatic life to a sufficient extent to represent a threat to children's health who eat fish with elevated concentrations of lead.

The Agency for Toxic Substances and Disease Registry (Cox, 1997) has, as part of a study of bioaccumulation of potentially hazardous chemicals in Putah Creek fish and other aquatic life near the University of California, Davis Department of Energy Laboratory for Energy-Related Health Research (LEHR) National Superfund site, developed a guidance value for lead in fish tissue. This value is based on a comparison between the consumption of drinking water at the U.S. EPA action level of 15 µg/L, assuming 2 L/day consumption, and the consumption of fish, assuming a 50 g/day consumption rate. The 50 g/day consumption rate is somewhat above the values typically used by the U.S. EPA of 6.5 g/day and 30 g/day, i.e. one meal per month or one meal per week, respectively. It is on the order of two meals per week. It is important to understand that the 15 µg/L lead drinking water action level is not necessarily a safe concentration. The U.S. EPA in developing that level recommended that the concentration be kept as low as possible. The 15 µg/L level should be protective of children in order to keep their blood lead levels below 10 µg/dL. The 10 µg/dL blood level is a value that is often used to indicate excessive blood lead that is possibly harmful to a child. There is some evidence, however, that blood lead levels below this concentration are adverse to children. It is concluded that any time the concentrations of lead in fish tissue used for human food are above about 0.3 mg/kg, there should be concern for children making extensive use of these fish as food.

Lee and Jones-Lee (1996b) developed a review of the current understanding of the relationships between the concentrations of chemical constituents in the water column or sediments and excessive bioaccumulation in aquatic life tissue. They have pointed out that it is not possible to predict the extent of bioaccumulation that will occur in fish tissue based on chemical concentrations in the water column and/or sediments. Site-specific evaluation of water column and/or sediment associated constituents have to be made in order to determine whether a constituent in either area is or could become a source of excessive bioaccumulation.

Chlorinated Hydrocarbons Beginning in the 1970s, the State Water Resources Control Board initiated a TSM program that included determination of the concentrations of the various potentially hazardous chemicals in aquatic life taken from the waters of the state (WRCB, 1995). The TSM has included sampling San Diego Creek and its tributaries as well as Upper Newport Bay fish. Presented below is a discussion of the TSM data for fish taken from San Diego Creek and Upper Newport Bay for the chemicals that have been analyzed as part of the WRCB TSM. Generally, the data reported for the hazardous chemical tissue concentration in fish is based on a composite of six fish taken within a certain area at one time.

Total Chlordane Chlordane is a chlorinated hydrocarbon pesticide that has been extensively used for termite control and other purposes. Its use is no longer allowed. Based on the approach used for evaluating excessive bioaccumulation of organic chemicals in San Francisco Bay (SFWRQCB, 1995), the critical concentration of total chlordane in fish for those who consume 30 g of fish per day, i.e., one meal per week, for a 70-kg adult is about 18 µg/kg. The corresponding value for consuming 6.5 g fish per day, i.e., one meal per month, for a 70-kg adult is 80 µg/kg. The WRCB's TSM database shows that fish, such as red shiner, taken from San Diego Creek at various locations as well as some of its tributaries such as Peters Canyon Channel, contain total chlordane of above the 18 µg/kg wet weight risk-base level that is considered hazardous to human consumption. Three sets of samples were taken of Newport Bay marine fish in 1990-1992. The total chlordane content of these fish was less than 18 µg/kg.

It may be concluded from the database available that fish in the tributaries of Upper Newport Bay contain excessive chlordane compared to a risk-based projected cancer risk level for humans who consume on the order of 30 g of fish per day taken from these waters. However, there are questions about whether there are any significant fisheries - human consumption of fish taken from the tributaries of Upper Newport Bay.

It would be appropriate to do additional sampling of fish from Upper Newport Bay to determine whether the three sets of samples taken in the early 1990s are representative of today's conditions. Further, additional sampling of fish in San Diego Creek and several of its tributaries should be conducted to confirm that the excessive levels of chlordane found primarily in the mid-to-late 1980s to early 1990s is still occurring today.

Aldrin Aldrin is a chlorinated hydrocarbon pesticide that is banned for further use because of its persistence and potential to be a health hazard to increase the cancer risk to those exposed to it. Sampling of San Diego Creek as well as Upper Newport Bay over the years has not found excessive concentrations of aldrin in fish tissue compared to the FDA action level of 0.3 mg/kg wet weight. The U.S. EPA has not established a guideline value for aldrin in fish tissue.

Total DDT DDT is a chlorinated hydrocarbon pesticide that was used for many years for a variety of pest control purposes. Its use was banned because of its persistence and its potential to cause cancer in those exposed to it. The critical level for total DDT based on the 30 g/day of fish consumption is 68.6 µg/kg. For a 6.5 g per day fish consumption rate, the critical concentration is 300 µg/kg. The San Diego Creek fish samples, with few exceptions, had total DDT concentrations in excess of both values. The three sets of fish collected from Upper Newport Bay in the early 1990s had total DDT concentrations below the 300 µg/kg hazard level, but two of the three sets of fish had DDT above the 68.6 level. The DDT level in the one set of fish was below the 68.6 µg/kg level.

The FDA action level for DDT is 5,000 µg/kg wet weight. Therefore, the fish in Upper Newport Bay as well as in San Diego Creek do not exceed the FDA action level for DDT. They are, however, considered hazardous based on a U.S. EPA risk-based screening level that is designed to protect humans from the one in a million increased cancer risk. There is need for additional sampling to determine whether the situation today is still the same as previously found with respect to total DDT in fish taken from Upper Newport Bay and its tributaries.

Dieldrin Dieldrin is a chlorinated hydrocarbon pesticide that had been banned because of its potential to bioaccumulate and cause cancer. The critical levels for dieldrin for 30 g per day fish consumption are 1.5 µg/kg and for 6.5 g per day is 7.0 µg/kg. The FDA action level for dieldrin is 300 µg/kg. Many of the fish taken from San Diego Creek and its tributaries had excessive concentrations of dieldrin compared to screening values based on both fish consumption rates. The detection limit that was used in these studies was 5 µg/kg. Therefore, it cannot be determined whether all the fish taken from San Diego Creek have excessive levels of dieldrin. All fish taken from Upper Newport Bay had less than the 5 µg/kg detection limit used for dieldrin analyses. There is need for additional sampling for dieldrin, using a more sensitive analytical approach to be sure that concentrations measured are at less than 1 µg/kg wet weight.

Total Endosulfan Total endosulfan is a chlorinated hydrocarbon pesticide that was banned because of its potential to bioaccumulate and cause cancer. The total endosulfan hazard level for consumption of 30 g of fish per day is 3,500 µg/kg. For the 6.5 g of fish per day consumption rate, it is 20,000 µg/kg. The concentrations of total endosulfan of fish taken from San Diego Creek and its tributaries as well as from Upper Newport Bay were well below these levels.

Heptachlor Epoxide Heptachlor epoxide is a chlorinated hydrocarbon pesticide that was banned because of its potential to bioaccumulate and cause cancer. The critical concentration for 30 g of fish per day is 2.6 µg/kg and for 6.5 g of fish per day is 10 µg/kg. The FDA action level is 300 µg/kg for heptachlor epoxide. Several samples of fish were taken from San Diego Creek that had concentrations of heptachlor epoxide between 5 and 16 µg/kg. Most of the samples taken from San Diego Creek and those taken from Upper Newport Bay had concentrations of heptachlor epoxide below the detection level of 5 µg/kg. The analytical methods used, however, do not detect heptachlor epoxide with sufficient sensitivity to determine whether excessive concentrations were present in the fish from Upper Newport Bay and San Diego Creek.

PCBs PCBs (arochlors) are chlorinated hydrocarbons (non-pesticides) that have been primarily used as an electrical transformer fluid as well as for a variety of other purposes. The excessive concentration for total arochlors (PCBs) for 30 g of fish per day consumption is 3 µg/kg and for 6.5 g of fish per day is 10 µg/kg. The FDA action level for total PCBs is 2,000 µg/kg. The total PCB content of fish taken from San Diego Creek and its tributaries was well in excess of both the 30 and 6.5 g of fish per day consumption rate. The fish were only taken from Upper Newport Bay and analyzed for PCBs in 1990 and 1991. No analyses were conducted in 1992. The 1990-1991 samples contained total PCBs at about 100 µg/kg, well above the critical level. It, therefore, may be concluded that PCBs are present in Upper Newport Bay tributaries and in the Bay fish at excessive concentrations that represent a public health hazard to those who eat the fish.

The U.S. EPA Great Lakes wildlife criterion for total PCBs is 0.2 to 1 µg/kg. Therefore, the San Diego Creek and Upper Newport Bay fish have sufficient concentrations of total PCBs to be potentially adverse to wildlife that eat the fish.

Toxaphene Toxaphene is a chlorinated hydrocarbon pesticide that was banned because of its potential to bioaccumulate and cause cancer. The critical concentrations for toxaphene are 21 µg/kg for 30 g of fish per day and 300 µg/kg for 6.5 g of fish per day. The concentrations of total toxaphene in fish taken from San Diego Creek and its tributaries were in some cases well above the critical concentration. The detection limit used for measuring toxaphene in fish from Upper Newport Bay was 100 µg/kg, and, therefore, there could be excessive toxaphene in Upper Newport Bay fish that was not detected by the monitoring program analytical methods used.

Oxadizon While there are no critical concentrations for oxadizon listed, the concentrations found in fish in some samples taken from Upper Newport Bay were in excess of 2,200 µg/kg. According to Rasmussen (1996), oxadizon is a herbicide that the manufacturer claims does not bioaccumulate in fish. However, it is accumulating in large amounts in Upper Newport Bay fish tissue. The hazard of this accumulation is unknown.

Overall Assessment It can be concluded that fish in San Diego Creek and several of its tributaries contain excessive concentrations for several formerly used chlorinated hydrocarbon pesticides, such as chlordane, DDT, and dieldrin. These fish also contain excessive concentrations of PCBs relative to those that are considered of increased cancer risk to humans who eat these fish as frequently as one meal per month.

The Toxic Substances Monitoring Program of the Water Resources Control Board does not include analysis for dioxins. It would be of interest to determine if excessive concentrations of dioxins are found in San Diego Creek and Upper Newport Bay fish.

It is unclear whether the excessive concentrations of chlorinated hydrocarbon pesticides and PCBs in San Diego Creek fish represent a human health hazard, even though the concentrations found within the fish tissue exceed human health advisory levels for the use of the fish as food. There is need to better understand whether there is any fishing in these tributaries to assess whether there is a human health hazard.

Based on studies in other places, there is likely to be a wildlife hazard due to excessive concentrations of some of the pesticides and PCBs in these fish for those animals and especially birds that eat the fish. PCBs and DDT are well-known to cause reproductive failure in fish-eating birds. This could be a problem associated with a bird population that consumes fish from San Diego Creek and its tributaries.

There is need for additional sampling of San Diego Creek and especially Upper Newport Bay to determine whether the various chlorinated hydrocarbon pesticides and PCBs, which in the early 1980s through the early 1990s were present in excessive concentrations in fish tissue, are still present in excessive concentrations today. These chemicals have not been used for a number of years, and, therefore, in many parts of the country their concentrations in fish are decreasing. Further, since other areas are finding excessive concentrations of dioxin in fish, dioxin should be measured in the San Diego Creek, and especially Upper Newport Bay fish.

Heavy Metals Based on the WRCB TSM data, the heavy metal content of San Diego Creek and its tributary fish as well as Newport Bay fish is generally below critical levels, except for an occasional exceedance of the mercury level of 0.14 µg/kg for the 30 g of fish per day consumption rate. Therefore, bioaccumulation of mercury in fish is a potential problem in both San Diego Creek tributaries and Upper Newport Bay. A similar situation exists with lead compared to the value that was developed by the Agency for Toxic Substances and Disease Registry (ATSDR) for the Putah Creek fish. There are some values of lead concentrations in fish tissue from Upper Newport Bay tributaries and the Bay that exceed the guideline value of 0.3 mg/kg.

The lead exceedances are not considered significant problems, however, since the number of exceedances compared to total number of samples is quite low. It would be appropriate to take an additional set of samples from Upper Newport Bay as well as at a couple of locations on San Diego Creek to confirm that the situation today with respect to mercury and lead in fish is still, as it has been in the past, at a low level of contamination and not a significant threat to human consumption of fish taken from these areas.

Mussel Watch For the period 1978 through 1995, mussels were suspended in cages at various locations in Upper Newport Bay. This was done as part of the WRCB's mussel watch program, where mussels are used to assess whether excessive concentrations of potentially hazardous chemicals accumulate within mussel tissue (WRCB, 1996a). Periodically, the mussels are removed from their cages and their tissue is analyzed for a number of chemical constituents of potential concern.

The total chlordane concentrations in the mussel samples taken from Upper Newport Bay typically ranged between the 18 µg/kg concentration value and 80 µg/kg. Similarly, the total DDT content of the mussels exposed in Upper Newport Bay ranged from less than the 68.6 µg/kg guideline value for 30 g of fish per day to less than the 300 µg/kg value for 6.5 g of fish consumed per day. Many mussels had concentrations between these two values. Similarly, the total PCB content of mussels suspended in Upper Newport Bay waters is typically above the 10 µg/kg guideline value for 6.5 g of fish per day consumption rate. Some samples accumulated total PCBs in excess of 400 µg/kg.

Some of the mussels accumulated cadmium in excess of the 2.2 mg/kg and 10 mg/kg guidance values. Many of the mussels accumulated cadmium between the two guideline values. A similar pattern was found for mercury accumulation in mussels. Many mussels accumulated mercury in excess of the 0.14 mg/kg guideline value for 30 g of shellfish consumption per day; there were only a few, however, that accumulated in excess of 0.6 mg/kg. While most of the mussels had lead concentrations below the ATSDR recommended limit, there were some mussels with concentrations of lead at or near that limit. Several heavy metals that are analyzed as part of the TSM do not have critical concentrations tissue values, such as chromium, copper, manganese, nickel, titanium, zinc, silver, aluminum, and arsenic. It is, therefore, not possible to judge whether the concentrations found are excessive. However, normally these metals do not represent significant threats to those who eat fish and other aquatic life.

Care must be exercised in using mussel watch data to interpret the actual bioaccumulation of hazardous chemicals that is occurring in edible organisms in a region, especially if they are near the critical concentration levels for excessive bioaccumulation. As discussed by Salazar et al. (1995), minor changes in some of the variables associated with mussel watch such as organism size, etc., within the range that is normally allowed, can significantly impact the bioaccumulation of constituents in mussel tissue. The exposure conditions that occur in mussel watch sampling can be significantly different from the exposure conditions that ambient water organisms experience in a region. It is, therefore, important that any regulatory activities devoted to bioaccumulation issues be focused on actual organisms that are used as food and not be based on mussel watch data, especially if the data is near the critical concentration value for a chemical of concern.

Need for Additional Studies There is need for additional monitoring of fish from Upper Newport Bay and San Diego Creek to establish the current levels of fish tissue contamination relative to those that are potentially hazardous for use of the fish as food. There is also need to better understand whether there is any significant use of San Diego Creek fish as human food. Because of the limited water available in San Diego Creek during much of the year and the limited size of the fish normally present in the Creek, it is likely that there is limited human health threat associated with consuming fish from the creek even if they still contain excessive concentrations of chlorinated hydrocarbon pesticides, PCBs, and mercury. There may, however, be a potential wildlife threat, especially to fish-eating birds due to the excessive concentrations of the chlorinated hydrocarbon pesticides and PCBs that could be present in San Diego Creek fish.

Aquatic life in some areas, especially associated with petroleum hydrocarbon refining and industrial processes that introduce large amounts of PAHs into a waterbody, has been found to have tumors, lesions, and other illnesses associated with the chemicals that are carcinogens. While this is apparently not a problem associated with urban area and highway stormwater runoff, it would be important to examine some of the aquatic organisms in an area receiving such runoff to determine if they have tumors, liver or other organ lesions, abnormal organs, etc., that could be attributable to the constituents in the runoff.

At this time, no information is available on whether aquatic life within Upper Newport Bay and its tributaries are experiencing disease due to pathogenic organisms as well as carcinogens and other chemicals that cause tumors and/or other abnormal tissue growth within the organism. Also, no information is available as to whether there are any endocrine or other hormone-active substances that impair Upper Newport Bay aquatic organism and water fowl reproduction/behavior. Crisp, et al. (1997) have recently issued a report on behalf of the U.S. EPA that concludes that insufficient information is available to determine whether there are hormone-disrupting chemicals in the environment that are adversely affecting public health and the environment. This is an emerging area of increasing national/international water quality concern that could be significant to Upper Newport Bay. It is likely, however, based on what is known from other areas, since generally, where these problems have been found, they appear to be associated with major industrial wastewater inputs. Problems of this type may be associated with past and possibly current pesticide/herbicide inputs to the Bay. The current pesticide/herbicide registration process used by the U.S. EPA does not properly evaluate the potential for these types of chemicals to be adverse to aquatic life and wildlife.

Since many chemicals of concern with respect to excessive concentrations in aquatic organism tissue are chemicals that are no longer being used, such as the chlorinated hydrocarbon pesticides and PCBs, it appears that the aquatic sediments and possibly the soils within the Upper Newport Bay watershed and within the Bay are the source of these chemicals that is maintaining the elevated concentrations within the aquatic life tissue. If additional studies show that aquatic life within San Diego Creek and Upper Newport Bay still contain excessive concentrations of many of the constituents of concern because of their human health threat, studies will need to be conducted to determine the specific sources of the constituents responsible for the excessive bioaccumulation. However, it is inappropriate to assume that the concentrations of constituents in sediments that tend to bioaccumulate are a reliable estimate of the significance of a sediment as a hazardous chemical source that accumulates to excessive levels.

As discussed by Lee and Jones-Lee (1996b), there are a wide variety of factors not related to the concentration of a hazardous chemical in sediments that control the availability of such chemicals for bioaccumulation. These are bulk chemical characteristics of the sediments that include total organic carbon (TOC), carbonate, hydrous metal oxide, and sulfide content, which control the ability of a constituent in sediments to be a source of constituents that bioaccumulate in aquatic organism tissue. Accordingly, low concentrations of a potentially hazardous constituent can readily bioaccumulate to higher levels within aquatic life tissue than high concentrations of the same constituent in a different sediment that has greater sediment binding for the constituent than the sediments that have lower concentrations.

The approach that must be used to address this issue is site-specific evaluations using aquatic organism exposure under controlled conditions to determine if a constituent in sediments is available for bioaccumulation. There are a variety of factors such as the opportunity for higher trophic organisms to be exposed to conditions that lead to bioaccumulation that influence whether available forms of constituents in sediments that must be evaluated on a site-specific basis to determine whether a chemical in sediments is, in fact, the source of the constituents that are bioaccumulating to excessive levels in the fish of a region.