2.0 Water Monitoring

Contents

Tables

Figures

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2.1 Background

This chapter presents a graphical and narrative summary of the Regional Monitoring Program (RMP) water monitoring results for 1998. This chapter also includes articles contributed by RMP investigators that provide interpretive summaries of specific water monitoring activities.

Water quality was monitored at twenty-two RMP Base Program stations. Parameters measured included conventional water quality parameters (salinity, temperature, total suspended solids; Figures 2.1-2.3), trace elements, trace organic contaminants, and toxicity (Figures 2.4-2.22). Two additional stations were sampled in 1998 for an Estuary Interface Pilot Study at Standish Dam (BW10) and Guadalupe River (BW15). Water was also sampled at two stations in the southern end of the Estuary in cooperation with the cities of San Jose (station C-3-0) and Sunnyvale (station C-1-3). In addition, the U.S. Geological Survey monitored conventional water quality parameters at shorter time scales to complement RMP monitoring activities.

Station locations are shown in Figure 1.1 in the Introduction. Water samples were collected in January, April, and July. Sampling dates and parameters measured at each station are shown in Table 1.3 in the Introduction. For trace elements, dissolved (0.45 µm filtered) and total (arsenic, chromium, mercury, and selenium) or near-total (cadmium, copper, lead, nickel, silver, and zinc) concentrations are presented in Figures 2.4-2.13. Dissolved (1 µm filtered) and total concentrations of trace organic contaminants are also presented in Figures 2.14-2.21. In addition, long-term trends in trace element and trace organics for each Estuary reach are provided in Figures 2.23-2.40. Detailed methods of collection and analysis are included the Description of Methods.

In order to compare water monitoring results among the major segments of the Estuary, the RMP stations are separated into six groups based on similarities in geography, water chemistry, and hydrodynamics: the Estuary Interface (BW10 and BW15), Southern Sloughs (C-1-3 and C-3-0), South Bay (seven stations, BA10 through BB70), Central Bay (five stations, BC10 through BC60), Northern Estuary (eight stations, BD15 through BF40), and the Rivers (BG20 and BG30).

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2.2 Water Quality Objectives and Criteria

In this report, comparisons to guidelines are made to provide a context for evaluating the condition of the Estuary in terms of contamination, and not for any regulatory purpose. Guidelines were selected based on guidance from the San Francisco Bay Regional Water Quality Control Board (SFBRWQCB; Lynn Suer, personal communication).

On August 5, 1997, the U.S. Environmental Protection Agency (U.S. EPA) published its proposed numeric water quality criteria for priority toxic pollutants for the State of California to fulfill the requirements of section 303(c)(2)(B) of the Clean Water Act (CWA). The U.S. EPA proposed this rule to fill a gap in California water quality standards that was created in 1994, when a State Court overturned the State's water quality control plans which contained water quality criteria for priority toxic pollutants. This left the State without numeric water quality criteria for many priority toxic pollutants as required by the CWA, necessitating action by the U.S. EPA.

Water quality guidelines for this report were taken from the U.S. EPA's proposed California Toxics Rule (U.S. EPA, 1997; CTR), and the Regional Water Quality Control Plan, San Francisco Basin (SFBRWQCB, 1995; Basin Plan). Criteria for the dissolved trace elements and the total organic compounds (dissolved + particulate fractions) were taken from the CTR. Objectives for total trace elements were obtained from the Basin Plan. These guidelines are listed in Table 2.1.

Different objectives and criteria apply to saltwater, estuarine, and freshwater portions of the Estuary. As defined by the Basin Plan, sites are defined as 1) freshwater when their salinity is below 5 parts per thousand (ppt) more than 75% of the time; 2) saltwater when their salinity is greater than 5 ppt more than 75% of the time; and 3) estuarine if salinity is intermediate, if estuarine organisms are present for significant periods, or based on an evaluation by the SFBRWQCB.

For estuarine locations, the Basin Plan specifies that the lower of the freshwater and saltwater objectives apply. RMP stations were classified as freshwater, estuarine, or saltwater based on an evaluation by the SFBRWQCB (Kim Taylor, 1998) of long-term data at RMP stations. The following stations were classified as estuarine: Sunnyvale (C-1-3), San Jose (C-3-0), South Bay (BA20), Petaluma River (BD15), San Pablo Bay (BD20), Pinole Point (BD30), Davis Point (BD40), Napa River (BD50), Pacheco Creek (BF10), Grizzly Bay (BF20), Honker Bay (BF40), Sacramento River (BG20), and San Joaquin River (BG30).

Water quality guidelines for six trace elements are calculated based on water hardness. In the RMP, hardness data are only collected at stations where the salinity is less than 5. For these trace elements, freshwater guidelines were calculated assuming a hardness of 100 mg/L for the designated estuarine stations where hardness data were not collected. Fresh water guidelines for these compounds are represented on the charts using a hardness value of 100 mg/L.

Selenium criteria are region-specific criteria for total recoverable selenium that apply to the entire Estuary (National Toxics Rule, U.S. EPA, 1995). A criterion for diazinon was not included in the proposed CTR, but a guideline developed by the California Department of Fish and Game (Menconi and Cox, 1994) was used in this report to evaluate the degree of contamination in the Estuary.

For some contaminants multiple guidelines exist that apply to different target organisms (aquatic life or humans) or different lengths or routes of exposure (e.g., 1 hour or 4 days). For this report, RMP contaminant data were compared to the lowest guideline for each contaminant. In general, trace element concentrations were compared to 4-day average guideline for aquatic life. This is considered appropriate by the SFBRWQCB since RMP data are probably indicative of conditions that persist longer than one day. Trace organic contaminant concentrations were compared to human health criteria based on consumption of organisms only, since RMP stations are all seaward of drinking water intakes in the Delta.

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2.3 Aquatic Bioassays

Laboratory bioassays using Estuary water were conducted at six RMP stations (Figure 2.22) during the wet-season sampling (January-February) and again in the dry-season sampling (July). Bioassays were conducted by exposing Mysids (Mysidopsis bahia) to Estuary water for seven days where percent survival was the endpoint. Detailed methods are included in the Description of Methods. Significant toxicity was determined by statistical comparison (t-tests) of field samples with controls.

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2.4 Water Trends

This section will be updated shortly.

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2.5.1 Discussion

El Niño storms of 1998 delivered exceptionally heavy precipitation and high streamflow to the San Francisco Bay watershed. The resulting hydrologic conditions in 1998 were typical of wet years in the Bay area. The distribution of contaminants in the Bay generally followed similar spatial and temporal patterns that were established in the first five years of RMP, as described in the 1996 Annual Report. However, extreme weather conditions persisted unusually late in the year and had a significant impact on the water quality conditions in both the April and July sampling periods.

A series of storms in early 1998 provided twice the monthly average precipitation in January and three times the monthly average for February (Roos 1998). During this time, the Sacramento-San Joaquin Delta outflow to the Bay peaked above 9,000 m3/s. The winter months were then followed by unusually wet weather in spring. The average precipitation for April was exceeded within the first two weeks, while four times the monthly average fell in May (CDWR 1998a, CDWR 1998b). Extended heavy rainfall in spring led to the highest monthly average Delta outflow in April, June, and July since the beginning of RMP. The extreme hydrologic conditions had a distinct impact on conventional water quality parameters during the April and July sampling periods. In late January and early February, surface salinity dropped from 28-30 psu (~17 % freshwater) in the South Bay and Central Bay to about 10 psu (~70 % freshwater) (Cloern 1999). In April, surface salinities were still around 10-16 psu in the South and Central Bay (Cloern 1999). Large loads of suspended solids (TSS), which often coincide with increased streamflow, entered the Bay well into the summer. In April, the Baywide mean TSS concentration peaked at 114 mg/L, the highest recorded average concentration for any cruise since RMP began. In addition, the average TSS concentration recorded during the July sampling exceeded all previously measured concentrations of TSS in summer RMP cruises.

2.5.2 The Effect of El Niño on Contaminant Concentrations

In 1998, contaminant concentrations tended to follow similar spatial and seasonal patterns observed in previous years of RMP water monitoring. High-flow conditions and associated high TSS concentrations that lasted unusually late in the year had a noticeable effect on some particle-associated contaminants, such as total trace elements. Similarly, high stream flows mobilized and transported above average concentrations of some dissolved contaminants to the Bay throughout the entire RMP sampling year.

Dissolved Trace Elements

Dissolved concentrations of many contaminants, including mercury, chromium, lead, selenium, and zinc, were generally elevated throughout the duration of the 1998 RMP study. Dissolved chromium reached average concentrations in April (0.54 µg/L) and July (0.30 µg/L) that exceeded all previous RMP results for those respective seasons. Similarly, the July sampling for lead, selenium, and zinc yielded average Baywide concentrations (0.057 µg/L, 0.58 µg/L, and 2.18 µg/L, respectively) that were higher than all of the previous summer sampling cruises in the RMP.

Average concentrations of dissolved mercury were elevated in January in the Estuary Interface (0.0093 µg/L) and Northern Estuary (0.0044 µg/L). The third and fourth highest concentrations of dissolved mercury in RMP history were measured in January at the Guadalupe River (BW15, 0.015 ug/L) and the Petaluma River (BD15, 0.014 ug/L). The average concentrations of dissolved zinc in January (3.2 µg/L) and July (2.18 µg/L) were elevated due to high concentrations in the Southern Sloughs, with maximum concentrations measured at the San Jose site (C-3-0) during both seasons. Similarly, the dissolved lead concentration in July (0.057 µg/L) was caused by a high average in the Southern Sloughs (0.26 µg/L), the highest concentration of lead measured in any of the reaches in 1998.

A few trace elements were heavily influenced by high concentrations measured in the Estuary Interface stations, which were included in the RMP beginning in 1996. Comparisons of 1998 data to previous years must be made with consideration of the influence of concentrations from these sites during the last three years. The average concentration of dissolved selenium in July (0.58 µg/L) was the highest recorded for this element since the beginning of RMP. This value was largely influenced by high concentrations in the Estuary Interface (4.14 µg/L) and Southern Sloughs (1.18 µg/L), exceeding 1997°s average (0.50 µg/L) and almost doubling the average selenium concentration measured in 1996 (0.32 µg/L). These sites also had higher concentrations of dissolved selenium in January and April compared to all of the other reaches in the Bay. Dissolved chromium concentrations in July (0.30 µg/L) were influenced by high concentrations in the Rivers and Southern Sloughs, while April concentrations (0.54 µg/L) were mostly influenced by high concentrations in the Northern Estuary and Estuary Interface stations. Chromium concentrations in April more than doubled the average Baywide concentration measured in the spring of 1996 (0.19 µg/L) and 1997 (0.24 µg/L).

Total Trace Elements

The extreme weather conditions during the January sampling led to the highest Baywide average concentration (0.058 µg/L) of total mercury since RMP began. In fact, the highest recorded mercury concentration (0.73 µg/L) in RMP history was measured in the Guadalupe River (BW15) in January. High flow conditions and associated TSS loads also had a significant impact on total concentrations of nickel, copper, chromium, lead, and zinc, which were consistently high through the July sampling. The highest Baywide average concentrations since the beginning of RMP were measured for total chromium (19.4 µg/L), copper (6.39 µg/L), and lead (2.67 µg/L) in April, and for total zinc (20.5 µg/L) in the July sampling. The average concentrations of nickel in April (11.2 µg/L) and July (8.8 µg/L) were the highest measured in RMP history for those particular seasons. These peak concentrations for the trace elements in April coincide with the highest Baywide TSS concentration (114 mg/L) ever measured by the RMP. Similar to their dissolved forms, increased concentrations of total trace elements in 1998 were influenced by high concentrations in the Estuary Interface and Southern Sloughs, and to a lesser extent, the Northern Estuary.

Organic Contaminants

Dissolved concentrations of the pesticides chlordane, chlorpyrifos, and dieldrin were highest in July at all stations in the Northern Estuary, Rivers, and Estuary Interface. The pesticide concentrations measured in these reaches displayed a seasonal variation of increasing concentrations from winter to summer. However, January concentrations were consistently higher at South Bay, Central Bay, and the Southern Sloughs compared to the two later RMP cruises.

Total (dissolved + particulate) chlordane and chlorpyrifos, among other organic contaminants in the 1998 RMP study, were significantly affected by laboratory contamination, as discussed in the following section. However, total chlordane concentrations in the Estuary Interface and Southern Sloughs were highest in April, with an average concentration of 4,400 pg/L measured in the Estuary Interface. Total concentrations of dieldrin in July were highest in the Northern Estuary, Rivers, and Estuary Interface. High concentrations of dissolved and particulate pesticides in the Northern Estuary and Estuary Interface suggest a steady contribution of contaminated sediment particles from the Central Valley during the extended periods of high flow conditions in 1998.

Total and dissolved PCBs followed similar patterns of contaminant distribution as the pesticides. Dissolved PCB concentrations in July were highest for all sites in the Northern Estuary, Rivers, and the Southern Sloughs, while January concentrations were generally higher in the South Bay and Central Bay. The highest average concentration (690 pg/L) was measured in the Southern Sloughs in July. Despite significant contamination of samples measured for total PCBs in January, unaffected data from April and July samplings still suggest that the highest concentrations of total PCBs in those months are found in the Estuary Interface, with an average concentration of 6,600 pg/L.

2.5.3 Effects of Laboratory Contamination and Interference on Organic Contaminants in the 1998 RMP

Water samples for organic compounds in 1998 suffered from more problems of blank contamination (which also appear as matrix interferences) than in previous years. This was in part due to a change in sourcing for sampling supplies made without notice by a vendor to the RMP contract lab. The lab attempted to correct for these interferences by post-extraction cleanup procedures and reanalysis of the samples, with limited success. These problems required additional evaluation and qualification of the data by SFEI. The lab has assured RMP that in the future they will "trust no one" and will perform cleaning procedures on all sampling supplies and measure contaminants in these cleaned supplies prior to sampling. Generally RMP does not employ a quantitation limit in the reporting of data, thus for any compound with a signal above the background noise, a value is given. Blank contamination indicates a probability of sample contamination, and analytes in sample sets with measurable blank contamination have qualifiers to indicate the increased uncertainty resulting from this. In the past, sample measurements were simply designated as being less than (B) or greater than (b) this increased uncertainty. However, due to the extensive contamination in the 1998 data set, an additional category (B) was created for the PCB data to designate data for congeners that were measured below the uncertainty introduced by blank contamination but whose ratios to measured congeners (in 1998) were sufficiently similar to previous years' ratios as to appear unaffected by contamination. This was possible for PCBs and not for other organic contaminant types because stable and thus predictable ratios among congeners have been established for PCBs based on past RMP sampling, while ratios among analytes within other classes of organics are variable and not highly predictable. The uncertainties from blank contamination and matrix interferences propagate into aggregate measures, like totals of dissolved and particulate fractions, and sums of compounds in contaminant groups (e.g. PCBs, PAHs). For totals, if either the dissolved or particulate fractions were unmeasurable due to contamination or interferences, no totals were provided because measurements in both fractions are usually of the same magnitude. Similarly, if a third of the contaminants (weighted by mass in previous years) for a sum were missing in the 1998 data, the sum was not provided (S). These qualifications are made to the data set to prevent the unmeasurable compounds from creating an apparent decrease in sums for contaminant groups where there is insufficient data. Suitability of the data for further interpretation is left for the user to determine given the field data and qualifiers presented. Preparation steps taken by the lab to minimize contamination and measure it before it might affect samples should prevent such extensive problems in the data for the future. Additionally, a process is underway to develop procedures for a whole method detection limit rather than the instrument measurement detection limit currently employed, which will give us a better indication of the uncertainties in the whole process of measuring blanks and samples.

2.5.4 Comparison to Water Quality Objectives

This section provides a brief overview of how 1998 data compare to relevant water quality guidelines (Table 2.1). Of the ten trace elements measured, concentrations of mercury, copper, nickel, chromium, lead, selenium, and zinc exceeded water quality guidelines on one or more occasions (Table 2.2). Nickel, mercury, and chromium were most frequently above guidelines. Although many of the results for trace organics were not available due to contamination, several of the reported organic concentrations, such as PCBs, DDTs, chlordanes, and dieldrin, were measured above water quality guidelines (Table 2.3). The sum of 40 PCB congeners were well above the congener-based ˆPCB criteria of 170 pg/L in all but eight of the samples analyzed.

2.5.5 Effects of Water Contamination

Previous RMP studies have assessed ambient water toxicity by determining the percent normal development and percent survival of aquatic organisms exposed to water samples from different reaches of the Bay. In 1998, the RMP modified its monitoring strategy in order to allocate more resources for studies on the effects of episodic storm events on water toxicity.

The baseline 1998 RMP study measured water toxicity at six sites located in the northern and southern reaches of the bay. Toxicity tests using Mysidopsis bahia indicated that none of the sites had significant water toxicity during the February and July samplings. The lowest percent survival (80%) was measured during the July cruise in the southern reaches of the bay at Dumbarton Bridge (BA30) and Sunnyvale (C-1-3).

The Episodic Toxicity study, described in the 1997 Annual Report, measured water toxicity at Guadalupe Slough, Pacheco Slough, and Mallard Island during the winter and spring of 1997-98. Statistically significant toxicity was consistently measured in water samples taken from all three of the stations. Because the samples were generally collected immediately following storm events, the study emphasized the influence of episodic events on water toxicity in the Bay.

2.5.6 References

Cloern, J.E., B.E. Cole, J.L. Edmunds, T.S. Schraga, and A. Arnsberg. 1999. Patterns of water-quality variability in San Francisco Bay during the first six years of the RMP, 1993-1998. Prepared for the San Francisco Estuary Institute, Oakland, CA.

Roos, M. 1998. Water year 1997-1998. Interagency Ecological Program Newsletter. 11(2):11-13.

CDWR. 1998a. Report to the California Water Commission on activities of the Department of Water Resources, April, 1998. California Department of Water Resources, Sacramento, CA.

CDWR. 1998b. Report to the California Water Commission on activities of the Department of Water Resources, May, 1998. California Department of Water Resources, Sacramento, CA.

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2.6 References

Menconi, M. and C. Cox. 1994. Hazard assessment of the insecticide diazinon to aquatic organisms in the Sacramento-San Joaquin river system. Administrative Report 94-2, California Department of Fish and Game, Rancho Cordova, CA.

SFBRWQCB. 1995. 1995 Basin Plan. San Francisco Bay Regional Water Quality Control Board. Oakland, CA.

U.S. EPA. 1995. Water Quality Standards; Establishment of Numeric Criteria for Priority Toxic Pollutants; States' Compliance Final Rule. Federal Register Vol. 62, No. 150, Dec. 22, 1992.

U.S. EPA. 1997. Water Quality Standards; Establishment of Numeric Criteria for Priority Toxic Pollutants for the State of California; Proposed Rule. Federal Register Vol. 62, No. 150, August 5, 1997.

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