science for a changing world Water Quality in the San Joaquin-Tulare Basins , 1992–95

U.S. Department of the Interior U.S. Geological Survey Circular 1159 A COORDINATED EFFORT

Coordination among agencies and organizations is an integral part of the NAWQA Program. We thank the following agencies and organizations who directly participated in the San Joaquin–Tulare Basins program.

Aquatic Habitat Institute Merced County Department of Agriculture Bureau of Reclamation, Mid Pacific Region Merced District California Department of Fish and Game Metropolitan Water District of Southern California California Department of Food and Agriculture, Agriculture Modesto Irrigation District Resources Board California Department of Health Services, Office of Drinking Flood Control Association Water San Luis and Delta-Mendota Water Authority California Department of Pesticide Regulation, Stanford University, Department of Geological and Environmental Monitoring Branch Environmental Sciences California Department of Water Resources Turlock Irrigation District California Regional Water Quality Control Board, Central United Anglers of California Valley Region U.S. Army Corps of Engineers California State Water Resources Control Board U.S. Department of Agriculture, Water Management California State University, Fresno, School of Engineering Research Laboratory California Waterfowl Association U.S. Environmental Protection Agency Environmental Defense Fund U.S. Fish and Wildlife Service Kenneth D. Schmidt and Associates, Quality U.S. Natural Resources Conservation Service Consultants University of California, Farm and Home Advisors Office Kern County Water Agency University of California, Davis, Department of Land, Air, and Conservation District Water Resources Larry Walker Associates, Inc., Environmental Engineering Water Resources Center and Management Westlands Water District Merced County Association of Governments

Front cover: . (Photograph by Sylvia V. Stork, U.S. Geological Survey) Back cover: Ground-water sampling in vineyards in eastern Fresno County, and Ecological survey at a site on the San Joaquin River. (Photographs by Neil M. Dubrovsky, U.S. Geological Survey) FOR ADDITIONAL INFORMATION ON THE NATIONAL WATER-QUALITY ASSESSMENT (NAWQA) PROGRAM:

San Joaquin–Tulare Basins Study Unit, contact:

District Chief Chief, NAWQA Program U.S. Geological Survey U.S. Geological Survey Water Resources Division Water Resources Division Placer Hall 12201 Sunrise Valley Drive, M.S. 413 6000 J Street Reston, VA 20192 Sacramento, CA 95819-6129

Information on the NAWQA Program is also available on the Internet via the World Wide Web. You may connect to the NAWQA Home Page using the Universal Resources Locator (URL): http://wwwrvares.er.usgs.gov/nawqa/nawqa_home.html

The San Joaquin–Tulare Basins Study Unit’s Home Page is at URL: http://water.wr.usgs.gov/sanj_nawqa/ Water Quality in the San Joaquin–Tulare Basins, California, 1992–95

By Neil M. Dubrovsky, Charles R. Kratzer, Larry R. Brown, JoAnn M. Gronberg, and Karen R. Burow

U.S. GEOLOGICAL SURVEY CIRCULAR 1159

CONTENTS

National Water-Quality Assessment Program ...... 1 Summary of major issues and findings ...... 2 Environmental setting and hydrologic conditions ...... 4 Major issues and findings ...... 6 Water-quality conditions in a national context ...... 20 Study design and data collection ...... 24 Summary of compound detections and concentrations ...... 26 References...... 32 Glossary ...... 34 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY Thomas J. Casadevall, Acting Director

The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Government

1998

Free on application to the

U.S. Geological Survey Information Services Box 25286 Federal Center Denver, CO 80225

Dubrovsky, Neil M. Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 / by Neil M. Dubrovsky, Charles R. Kratzer, Larry R. Brown, Jo Ann M. Gronberg, Karen R. Burow . p. cm. — (U.S. Geological Survey Circular : 1159) Includes bibliographical references (p. ). ISBN 0-607-89190-4 1. Water quality—California—San Joaquin River Watershed. 2. Water quality—California— Watershed. I. Dubrovsky, N. M. II. Series. TD224.C3W369 1998 363.739’42’09794—dc21 98-12058 CIP NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

EXPLANATION Began in 1991 Began in 1994 Began in 1997 Not scheduled yet

Knowledge of the quality of the Nation's streams and aquifers is important because “The scientific and of the implications to human and aquatic health and because of the significant costs technical information associated with decisions involving land and water management, conservation, and contained in this report regulation. In 1991, the U.S. Congress appropriated funds for the U.S. Geological provides valuable Survey (USGS) to begin the National Water-Quality Assessment (NAWQA) Program to help meet the continuing need for sound, scientific information on the areal extent assistance in of the water-quality problems, how these problems are changing with time, and an California’s efforts to understanding of the effects of human actions and natural factors on water quality better understand and conditions. implement programs The NAWQA Program is assessing the water-quality conditions of more than 50 of to address water the Nation's largest river basins and aquifers, known as Study Units. Collectively, resource issues—not these Study Units cover about one-half of the and include sources of only in the San drinking water used by about 70 percent of the U.S. population. Comprehensive Joaquin–Tulare assessments of about one-third of the Study Units are ongoing at a given time. Each Study Unit is scheduled to be revisited every decade to evaluate changes in water- Basins, but throughout quality conditions. NAWQA assessments rely heavily on existing information col- the state.” lected by the USGS and many other agencies as well as the use of nationally consis- tent study designs and methods of sampling and analysis. Such consistency simulta- Walt Pettit, neously provides information about the status and trends in water-quality conditions Executive Director, in a particular stream or aquifer and, more importantly, provides the basis to make California State Water comparisons among watersheds and improve our understanding of the factors that affect water-quality conditions regionally and nationally. Resources Control Board This report is intended to summarize major findings that emerged between 1992 and 1995 from the water-quality assessment of the San Joaquin–Tulare Basins Study Unit and to relate these findings to water-quality issues of regional and national con- cern. The information is primarily intended for those who are involved in water- resource management. Indeed, this report addresses many of the concerns raised by regulators, water-utility managers, industry representatives, and other scientists, engi- neers, public officials, and members of stakeholder groups who provided advice and input to the USGS during this NAWQA Study-Unit investigation. Yet, the information contained here may also interest those who simply wish to know more about the qual- ity of water in the rivers and aquifers in the area where they live.

Robert M. Hirsch, Chief Hydrologist

U.S. Geological Survey Circular 1159 SUMMARY OF MAJOR ISSUES AND FINDINGS

CALIF This report summarizes the major findings of the National Water-Quality Assessment (NAWQA) for the San Joaquin–Tulare Basins, California. The brief statements of the major findings that follow are expanded on later in this report (p. 6–19). Comparisons of data within this Study Unit with data from all 20 Study Units nationwide are given in descriptive (p. 20–23) and tabular (p. 26–31) formats. Additional information on the methods, approaches, and findings of all the investigations of the San Joaquin–Tulare Basins NAWQA studies is available in the technical reports listed on pages 32–33. Though this report is an integral part of a national study, it also is intended to serve as a stand-alone resource for anyone interested in water quality in California. Toxicity to Aquatic Organisms in Streams Attributed to Pesticides The California Water Resources A wide variety of pesticides occur in the San Joaquin River and its , Control Board has set a goal of some at concentrations high enough to adversely impact aquatic life. zero toxicity in surface water in the • Forty-nine pesticides were detected in the San Joaquin River and three San Joaquin River system. This subbasins, 22 of which were detected in more than 20 percent of the samples. goal is based on concerns for Available drinking-water standards were not exceeded, but the concentrations maintenance of anadromous fish, of seven pesticides exceeded the criteria for the protection of aquatic life. endangered fish in the • Pesticide occurrence is related to the timing and spatial distribution of Sacramento–San Joaquin Delta, pesticide application; the most frequent occurrence and highest concentrations and human health. Toxicity may generally coincide with the time of heaviest agricultural application. result from several causes, but • Crop type and basin characteristics affect spatial and seasonal variability of generally has been attributed to pesticide occurrence. pesticides from agricultural nonpoint sources. High concen- • The main source of organophosphate insecticides is the application to trations of organophosphate dormant orchards. Concentrations of organophosphate insecticides in runoff insecticides, resulting from appli- are high, and highly variable, during winter storms. Peak diazinon concen- trations in Orestimba Creek, in the Merced and the Tuolumne Rivers, and in cation to some orchards during the the main stem of the San Joaquin River frequently exceeded levels that can be winter, are of particular concern. acutely toxic to some aquatic life. (p. 6–9) • Diazinon and other pesticides were also found to be transported to the in stormwater runoff from the Modesto urban area. Potential for Adverse Effects on Biota from Pesticides in Bed Sediment and Biota Long-banned organochlorine Long-banned organochlorine insecticides continue to be transported to streams insecticides, such as DDT, are by soil erosion of contaminated agricultural fields, resulting in contamination of bound to soil particles in areas of suspended sediment, bed sediment, and aquatic organisms. past application. The soils and associated bound pesticides are • Concentrations of organochlorine insecticides, such as DDT, toxaphene, and chlordane, in tissues of clams and fish from the San Joaquin River and its transported to streams by soil western tributaries, were high relative to national values obtained in the 1970s erosion during natural or irrigation- and 1980s. related runoff. Once in the stream, organochlorine insecticides are • Concentrations of DDT compounds in fine-grained bed sediments and tissue taken up by organisms and bio- samples are correlated, suggesting that bioaccumulation is taking place. accumulated through the food chain. These compounds have • Most whole-water concentrations of p,p´-DDT, chlordane, dieldrin, and been shown to be harmful to wild- toxaphene exceeded chronic criteria for the protection of freshwater aquatic life and humans that consume life. them. (p. 10–11) • Runoff from winter storms will continue to deliver a substantial load of sediment-bound organochlorine insecticides to the San Joaquin River, even if irrigation-induced soil erosion is reduced. Nutrient Concentrations in the San Joaquin River Generally Support the Beneficial Uses Designated beneficial uses for Some nitrate and ammonia concentrations exceed criteria in some small the San Joaquin River include tributaries, but generally do not limit beneficial uses in the main stem of the San drinking water and the aquatic Joaquin River. ecosystem. Nitrate and • Mud and Salt Sloughs account for only about 10 percent of the streamflow but contribute nearly half the nitrate load in the San Joaquin River. ammonia criteria have been set

2 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 SUMMARY OF MAJOR ISSUES AND FINDINGS by USEPA to protect these bene- • Nitrate concentrations in the San Joaquin River have been increasing over ficial uses. The San Joaquin River the last 40 years, but concentrations are still well below the drinking-water Basin has many sources of nitrate standard. and ammonia: fertilizer and • Ammonia criteria were frequently exceeded in Turlock Irrigation District manure, subsurface agricultural lateral 5, and occasionally in Orestimba Creek and Spanish Grant Drain. None of the samples collected in the main stem of the San Joaquin River exceeded drains, dairies, and wastewater- criteria during 1993–95. treatment plants. (p. 12–13) Habitat Disruption and Water Chemistry Have Adversely Affected Native Fish Populations Development of water resources in Fish communities in the San Joaquin River and its tributaries change in response the San Joaquin River drainage, to water chemistry and habitat quality in a pattern suggesting that human including the Sacramento-San activities, including agriculture, are important factors in controlling the distri- Joaquin Delta, has been accom- bution and abundance of fish species. Fish communities in the lower San Joaquin panied by large-scale changes in River were highly degraded compared with other NAWQA Study Units, as was the aquatic ecosystems, including stream habitat at some sites. fish populations. Anadromous • Introduced fish species outnumber native fish species by almost 2 to 1. have declined, along with other migratory and resident native • In the lower San Joaquin River drainage, four groups of sites can be defined fish species. Though there are on the basis of fish communities. Native species were most common near the likely multiple reasons for declines foothill and were gradually replaced by different groups of introduced in native fish species, the roles of species in downstream areas where land use is dominated by agriculture and water chemistry and habitat degra- other human activities. dation have never been addressed • The appeared to provide the best habitat for native species on a basinwide basis. (p. 14–15) of the three major tributaries studied, possibly because of the way flow is managed in the Stanislaus River compared with that of the Tuolumne and Merced Rivers. • Fish communities provide a useful assessment of overall stream health of streams. Though the analysis cannot separate the individual effects of water chemistry (including toxicity) and habitat quality, both appear to be important. Drinking-Water Supplies From Ground Water Have Been Degraded by Fertilizers and Pesticides Ground water is the primary Nitrate concentrations in ground water frequently exceeded drinking water source of drinking water for the standards; however, pesticide concentrations rarely exceeded drinking-water majority of the population in the standards, with the notable exception of 1,2,-dibromo-3-chloropropane (DBCP). eastern San Joaquin Valley. • Nitrate concentrations in ground water in the eastern San Joaquin Valley Millions of pounds of pesticides exceeded the U.S. Environmental Protection Agency (USEPA) drinking-water and fertilizer have been used on standard in about one fourth of the domestic water-supply wells sampled. agricultural land in the valley. Prior • Nitrate concentrations in shallow ground water were related to the overlying data have shown ground-water agricultural land-use setting; concentrations varied among different agricul- contamination by agricultural tural land-use settings and were linked to fertilizer application, physical characteristics of the sediment, and biochemical processes in ground water. nonpoint sources. (p. 16–19) • Nitrate concentrations in ground water have increased since the 1950s. From 1950 to 1980, the largest source of nitrate—nitrogen fertilizer—also increased from 114 to 745 million pounds per year. • Pesticides were detected in about two-thirds of the ground-water samples collected from domestic water supply wells, but concentrations of most pesticides were low—less than 0.1 microgram per liter (µg/L). • DBCP concentrations exceed the USEPA drinking-water standard of 0.2 µg/L in 20 percent of the domestic water supply wells sampled. Data from monitoring wells show that DBCP concentrations generally decrease with depth and are highly variable near the water table. • Pesticide concentrations in ground water generally have not increased in the last decade on the basis of a small number of wells sampled (19) during 1986–87 and again in 1995. Direct comparison of the data is difficult because of changes in detection limits.

U.S. Geological Survey Circular 1159 3 ENVIRONMENTAL SETTING AND HYDROLOGIC CONDITIONS

The San Joaquin–Tulare Basins NAWQA Study Unit is of irrigated agriculture, which affects the quality of both located in and includes the San Joaquin surface and ground water in the valley. Valley, the eastern slope of the Coast Ranges, and the Irrigation return water may reach surface water as direct western slope of the . runoff (tailwater), as water from subsurface drainage The Sierra Nevada are predominantly forested land, and systems installed to control the water table, or as ground the Coast Ranges and the foothills of the Sierra Nevada are water discharged through riverbeds. The result can be rangeland. Almost the entire valley floor is used for increased concentrations of dissolved solids, nutrients, agricultural land. In 1987, about 10.5 million acres in the pesticides, and, in some areas, trace elements. Irrigation is San Joaquin Valley was farmland (San Joaquin Valley the largest source of recharge to the regional aquifer, and this Drainage Program, 1990, p. 50). Abundant water, combined ground-water recharge can contain higher concentrations of with the long growing season, results in an exceptionally dissolved solids than natural recharge in the past. This productive agricultural economy in the San Joaquin Valley. recharge also may contain elevated concentrations of In 1987, approximately 10.2 percent of the total value of nutrients, pesticide residues, and trace elements. agricultural production in the United States came from 15,000 48 California, 49 percent of which, or $6.82 billion, was from TOTAL LAND AREA = 31,200 square miles the San Joaquin Valley. 40 Thirty-eight percent of the surface water is imported from the Sacramento–San Joaquin Delta through the Delta- 10,000 30 Mendota Canal and (U.S. Bureau of Reclamation, 1990; California Department of Water Resources, 1991). Most of the rest of the surface water is 20 5,000 from the Sierra Nevada. Surface water from the Sierra Nevada is of very high quality, but major changes in water 10 quality occur when surface water enters the San Joaquin AREA, IN SQUARE MILES PERCENTAGE OF TOTAL AREA Valley. These changes are primarily due to the large amount 0 0

121 120 LAND WATER TUNDRA WETLAND URBAN OR

EXPLANATION r RANGELAND

e FOREST LAND Riv BARREN LAND s BUILT-UP LAND LAND USE ne AGRICULTURAL um er os Riv Urban C ne lum 16,000 Agriculture oke 110 M 100% SURFACE WATER Rangeland iver 100 ras R 14,000 93% Forest 38 Calave GROUND WATER 90 Tundra er Riv 12,000 slaus Other Stani 80

S 10,000 a 70 n e River J Tuolumn o a 60 q er 8,000 u iv i R n ed D c 50 Mer e er l v 6,000 t i 40 a la R - chil M R how M i C ad 30 e ve e 4,000 nd r ra o C WATER WITHDRAWALS

37 WATER WITHDRAWALS, t PERCENTAGE OF TOTAL a C an 20 Los an al Banos al 2,000 5% <1% <1% <1% 0% Creek 10 F C IN MILLIONS OF GALLONS PER DAY a re li s 0 0 fo no rn S ia lo r u ve gh Ri ngs Ki er iv TOTAL R

L SERVED o h SERVED s ek a Ga e e S tos C r w I a

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SAN iv COMMERCIAL A ule R er

C T JOAQUIN N F

36 PUBLIC SUPPLY

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i

A C V a

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S n a

D THERMOELECTRIC T t DOMESTIC SUPPLY

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iver Irrigation of agricultural land on the valley floor is the n R er K primary use of water in the San Joaquin–Tulare Basins.

35

4 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 ENVIRONMENTAL SETTING AND HYDROLOGIC CONDITIONS

The distribution of precipitation, and consequently runoff, temporal distribution of precipitation during the intensive in the San Joaquin–Tulare Basins is highly influenced by data collection phase followed this pattern, with slightly topography. Mean annual precipitation on the valley floor greater departure from average during drier years. ranges from less than 5 inches in the south to 15 inches in the Total streamflows at the San Joaquin River near Vernalis north. Precipitation in the Coast Ranges varies from less than site, during WYs 1992–94, were 48 to 78 percent below 10 inches (at Panoche 2 W) to more than 20 inches. Average average, whereas streamflow during WY 1995 was 91 annual precipitation in the Sierra Nevada, mostly in the form percent above average. Eighty-five percent of the streamflow of snow, ranges from about 20 inches in the lower foothills to normally occurs from November to March in the Coast more than 80 inches at some higher elevation sites Ranges, reflecting the pattern of precipitation. In the Sierra (Calaveras Big Trees). Nevada, and in the San Joaquin–Tulare Basins as a whole, Hydrologic conditions during the intensive data collection only 40 to 50 percent of the streamflow occurs from phase (1992–95 water years [WYs]) of the San Joaquin– November to March; the greater proportion of the Tulare Basins NAWQA were variable. Precipitation in WYs streamflow comes from snowmelt stored in the reservoirs, 1993 and 1995 was above the 1961–90 average of which is not released until later in the spring. During the 19.4 inches (42 and 70 percent, respectively). The 1992 and intensive data-collection period there was little departure 1994 WYs were slightly below average (16 and 26 percent, (less than 10 percent) from these temporal patterns, except in respectively). Approximately 80 percent of the annual 1995 at the San Joaquin River near Vernalis where more of precipitation normally occurs from November to March. The the streamflow occurred during the spring.

Representative of the entire study area 15 60 San Joaquin-Tulare Basins San Joaquin River near Vernalis

10 40

5 20 EXPLANATION MONTHLY MEAN RANGE OF HISTORICAL DATA, CUBIC FEET PER SECOND PRECIPITATION, IN INCHES WATER YEARS (WY) 1961-1990 0 DISCHARGE, IN THOUSAND 0 O N D J F M A M J J A S O N D J F M A M J J A S MEDIAN PRECIPITATION MONTH MONTH WY 1992 SITE WY 1993 DISCHARGE Representative of the Sierra Nevada area WY 1994 SITE 40 8 WY 1995 Calaveras near Mokelumne Hill Big Trees 6

Mokelumne River near Mokelumne Hill 20 4

2 MONTHLY MEAN San Joaquin Calaveras CUBIC FEET PER SECOND

Big Trees PRECIPITATION, IN INCHES 0 DISCHARGE, IN THOUSAND 0 River near O N D J F M A M J J A S O N D J F M A M J J A S Vernalis MONTH MONTH

Representative of the Coast Ranges area 10 3 Panoche 2 W Los Gatos Creek above Nunez Canyon Panoche 2 W No Data for March 1993 2

Los Gatos 5 Creek above 1 Nunez Canyon MONTHLY MEAN DISCHARGE, IN HUNDRED CUBIC FEET PER SECOND PRECIPITATION, IN INCHES 0 0 O N D J F M A M J J A S O N D J F M A M J J A S MONTH MONTH

Hydrologic conditions during the intensive data-collection phase were highly variable.

U.S. Geological Survey Circular 1159 5 MAJOR ISSUES AND FINDINGS—Pesticides in the San Joaquin River Basin

Forty-nine of the 83 pesticides majority of pesticide application in the analyzed for were detected. The most Study Unit is for agricultural use. commonly occurring ones were the Seventy percent (38 of 54) of the herbicides simazine, dacthal, metol- pesticides with known application achlor, and EPTC, and the insecticides were detected. Detection frequency is diazinon and chlorpyrifos. Concentra- also related to the amount of pesticide tions of the detected pesticides usually applied; 4 of the 6 most commonly Merced were low, but highly variable: median River detected pesticides were among the 10 Basin concentrations of the six most fre- most heavily applied of the pesticides Orestimba Salt Creek Slough quently detected pesticides ranged analyzed: chlorpyrifos, diazinon, Basin Basin from 0.004 µg/L for dacthal to 0.050 EPTC, and simazine. µg/L for simazine, and 10 pesticides There is often a correspondence Selected subbasins sampled in the had maximum concentrations greater between the time a pesticide was San Joaquin River Basin. than 1 µg/L. Over half of the pesticides applied and when, and at what con- detected have no established aquatic- centration, it was detected (Panshin Pesticide criteria for the life criteria, and the potential for these and others, in press). The maximum protection of aquatic life were compounds to induce toxicity, endo- application and occurrence generally frequently exceeded crine disruption, or impaired immune coincided for 19 pesticides (for response is not well known. Although USEPA drinking-water example, EPTC), usually during the standards were not exceeded, criteria summer irrigation season. In contrast, Detections of pesticides in several pesticides (for example, chlor- for the protection of freshwater aquatic surface waters are related to life were exceeded in 37 percent of the pyrifos) attained their maximum con- stream samples (Panshin and others, in where and when pesticides centration in streams during winter press). Concentrations of seven pest- are applied runoff rather than at the time of maximum application. This indicates icides exceeded criteria for aquatic The California Department of life; these are the herbicides diuron that, in some cases, winter runoff was Pesticide Regulation maintains more efficient than irrigation return and trifluralin; and the insecticides detailed information on pesticide flows at transporting pesticides from azinphos-methyl, carbaryl, chlor- application. This information includes the site of application to a stream. pyrifos, diazinon, and malathion. Forty type of compound, location, date, During the autumn there is neither percent of these exceedances are amount applied, and target crop for rainfall nor irrigation, resulting in attributed solely to diazinon. each pesticide application. The vast relatively few detections. The exceedance of a water-quality

criteria indicates a strong probability Simazine that aquatic species are being TRUCK CROPS ALMONDS Diazinon BEANS VINEYARDS adversely affected. Aquatic life criteria EPTC ALFALFA CORN COTTON OTHER are determined by exposing test Dacthal RICE organisms to water containing only Metolachlor one pesticide at a time. Most of the Chlorpyrifos samples tested in this study contained Cyanazine mixtures of more than 7, and as many Diuron as 22, different pesticides. The toxicity Carbaryl of combinations of pesticides is largely Trifluralin unknown, but there is some potential Pebulate for additive or interactive effects. PESTICIDE Alachlor Pesticides were detected in all but Propargite one of the 143 surface-water samples Molinate collected during calendar year 1993 Fonofos from four sites—Orestimba Creek, Malathion Salt Slough, Merced River, and San Napropamide Joaquin River near Vernalis. These Methomyl sites were selected to evaluate how the Pronamide concentrations of dissolved pesticides 0 100 200 300 vary in contrasting parts of the basin APPLICATION, IN THOUSAND POUNDS ACTIVE INGREDIENT and during different seasons (Panshin The diversity of crops and pesticides applied is large in the San Joaquin River Basin and others, in press). (California Department of Pesticide Regulation, 1994).

6 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 MAJOR ISSUES AND FINDINGS—Pesticides in the San Joaquin River Basin

80 0.06 10 includes large areas of wetlands and APPLIED cotton; the slough does not have a DISCHARGE 8 60 DETECTED significant upland area within its basin, 0.04 NOT DETECTED and its streamflow is dominated by 6 agricultural drainage much of the year. 40 Twenty-five herbicides and eight 4 0.02 insecticides were detected at this site. 20 ACTIVE INGREDIENT 2 Pesticides detected more frequently at IN THOUSAND POUNDS IN MICROGRAMS PER LITER Salt Slough than at other sites were CHLORPYRIFOS CONCENTRATION, CHLORPYRIFOS APPLICATION, 0 0 0 atrazine, cyanazine, diuron, EPTC, JFMAMJJASOND malathion, and molinate. The presence 1993 30 0.20 10 of these pesticides is attri-buted to application primarily on cotton, rice, 8 0.15 alfalfa, and truck crops. 20 The Merced River is one of three 6 tributaries that carry runoff from the 0.10 Sierra Nevada year round, often as 4 10 reservoir release, and runoff from agri- 0.05 DISCHARGE, IN THOUSAND CUBIC FEET PER SECOND cultural areas during the summer.

EPTC CONCENTRATION, 2

IN MICROGRAMS PER LITER Although 26 pesticides were detected POUNDS ACTIVE INGREDIENT 0 0 0 in this river, the frequency of detection EPTC APPLICATION, IN THOUSAND JFMAMJJASOND and concentrations were usually much 1993 lower than corresponding levels in the Data for monthly pesticide application in the San Joaquin River Basin and concen- other two basins. This relatively low tration in samples in the San Joaquin River near Vernalis show that the occurrence occurrence is due to a combination of and application are often related in the summer, whereas the concentration may peak in the winter in spite of heavier application in the summer. factors: the generally coarse-grained soils of the eastern San Joaquin Valley Crop type and basin propargite. The presence of these result in little surface runoff during characteristics affect spatial pesticides is attributed to past or pre- rainfall or irrigation; and pesticides and seasonal variability of sent application primarily on dry beans that do reach the Merced River are pesticide occurrence and truck crops. diluted by the release of the relatively Salt Slough drains a low-lying part pesticide-free water from a reservoir in Orestimba Creek is typical of the of the San Joaquin Valley, which the Sierra Nevada foothills. small western tributaries to the San Joaquin River where streamflow is Orestimba Creek Salt Slough Merced River predominantly agricultural runoff Simazine Diazinon during the summer, but may also EPTC include large amounts of runoff from Dacthal the nonagricultural Coast Ranges Metolachlor Chlorpyrifos during the winter. A greater variety of Cyanazine pesticides were detected here (28 Atrazine Diuron herbicides and 12 insecticides) com- Carbaryl pared with the other sites. During the Trifluralin winter, high concentrations of some DDE, p,p’- Pebulate pesticides occur for brief periods PESTICIDE Alachlor because of transport by rainfall runoff Propargite Molinate (see the following section and Fonofos Domagalski and others, 1997). During Malathion Napropamide the irrigation season, a large number of Dieldrin pesticides—usually greater than Methomyl 15—were detected (Panshin and Pronamide others, in press). Pesticides detected 0050 100 0050 100 0050 100 DETECTION FREQUENCY, IN PERCENT more frequently in Orestimba Creek than at the other sites include DDE, Some pesticides were detected frequently in samples from all three subbasins, whereas dieldrin, fonofos, napropamide, and other pesticides were detected in samples from only one or two subbasins.

U.S. Geological Survey Circular 1159 7 MAJOR ISSUES AND FINDINGS—Sources and Transport of Pesticides in the San Joaquin River Basin

Stanislaus River Basin

Tuolumne River Basin

Merced River Bear Basin Creek Basin Orestimba Creek Basin San Joaquin River Basin showing boundaries of Orestimba Creek, Bear Almond orchard spraying (photograph by Dave Kim, Creek, Merced River, Tuolumne River, California Department of Pesticide Regulation). and Stanislaus River Basins (almond The organophosphate insecticide Transport of orchards shown in green). diazinon is used for many agricultural diazinon in the San 1.0 5,000 and urban applications. The main agri- January PRECIPITATION Joaquin River is 1994 DIAZINON cultural application of diazinon in the Storm related to timing of 0.8 APPLICATION 4,000 San Joaquin River Basin occurs during the winter to control wood-boring diazinon application February 1994 insects in dormant almond orchards. and storms 0.6 Storm 3,000 This application period coincides with The main factors the rainy season. involved in the transport 0.4 2,000 of diazinon in the San Concentrations of diazinon Joaquin River are the during storm runoff timing of diazinon appli- 0.2 1,000 frequently exceeded toxic cations and the occurrence PRECIPITATION, IN INCHES PER DAY levels of sizable storms during 0 0

D J FM DIAZINON APPLICATION, IN POUNDS PER DAY Diazinon concentrations during January and February. 1993 1994 During 1991–93, 74 per- winter storm runoff in Orestimba About half of the total agricultural application of diazinon in Creek, and in the Merced, Tuolumne, cent of diazinon transport 1994 occurred during two dry periods preceding storms. and San Joaquin Rivers frequently in the San Joaquin River exceeded 0.35 µg/L, a concentration occurred during January January and February. The overall shown to be acutely toxic to water fleas and February. In 1994, about half of amount of diazinon transported in the (Kuivila and Foe, 1995; Domagalski the diazinon application in agri- San Joaquin River during these storms and others, 1997; Kratzer, 1997). cultural areas of the San Joaquin River was only about 0.05 percent of the Although this level is acutely Basin occurred during two dry periods amount applied during the preceding preceding sampled storms during dry periods. toxic to water fleas, the effect on other 1.2 10,000 organisms is largely DISCHARGE 1.0 unknown. Concentra- CONCENTRATION 8,000 tions in the Stanislaus 0.8 River never exceeded 6,000 0.35 µg/L. On the 0.6 basis of daily samples 4,000 0.4 from the San Joaquin 2,000 River during 1991–94, 0.2 DAILY MEAN DISCHARGE, IN MICROGRAMS PER LITER DIAZINON CONCENTRATION, diazinon concentra- IN CUBIC FEET PER SECOND 0 0 tions only exceeded F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A 0.35 µg/L during Janu- 1991 1992 1993 1994 ary and February YEAR storm runoff (Mac- Diazinon concentrations at the San Joaquin River near Vernalis exceeded concentrations toxic to aquatic Coy and others, 1995). life (0.35 microgram per liter) only during January and February because of storm runoff.

8 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 MAJOR ISSUES AND FINDINGS—Sources and Transport of Pesticides in the San Joaquin River Basin

A dye-tracer study was done during 6 the February 1994 storm to estimate WEST-SIDE CREEKS MERCED RIVER traveltimes in the San Joaquin River 5 WEST-SIDE CREEKS OTHER EAST-SIDE CREEKS system (Kratzer and Biagtan, 1997). AND OTHER AND BEAR CREEK EAST-SIDE CREEKS BEAR CREEK On the basis of storm sampling during 4 1993–94 and estimated traveltimes, STANISLAUS RIVER SAN JOAQUIN RIVER ephemeral west-side creeks probably TUOLUMNE RIVER TOTAL were the main diazinon source early 3 OTHER EAST-SIDE during the storms, whereas the CREEKS Tuolumne and Merced Rivers and east- 2 side drainages directly to the San DIAZINON LOAD, IN POUNDS Joaquin River were the main sources ACTIVE INGREDIENT PER DAY 1 later (Domagalski and others, 1997; Kratzer, 1997). 0 7 8 9 10 11 12 13 More pesticides were FEBRUARY 1994 detected in runoff from urban Most diazinon in the San Joaquin River comes from west-side creeks, the areas than from agricultural Tuolumne and Merced Rivers, and direct drainage from the east side. areas in the Tuolumne River all pesticides except napropamide and source of transport for the other Basin, but pesticide transport simazine. The lower occurrence and pesticides could not be determined. was usually greater in runoff concentrations in agricultural runoff In most cases, the occurrence and from agricultural areas was partly attributed to dilution by relative concentrations of pesticides in nonstorm base flow in the Tuolumne The occurrence, concentrations, and storm runoff from agricultural and River and by storm runoff from transport of dissolved pesticides in urban areas were related to pesticide storm runoff were compared in the nonagricultural land (primarily native applications. Some pesticides detected Tuolumne River Basin for two land vegetation) (Kratzer, in press). frequently, and in relatively high uses: agricultural areas and the Transport of chlorpyrifos, diazinon, concentrations, in the storm drains did Modesto urban area. Both storms metolachlor, napropamide, and not relate to reported use. However, followed the main application period simazine was greater from agricultural unlike agricultural use, reporting of of pesticides on dormant almond areas than from urban areas. Transport pesticide use in urban areas is orchards. Six pesticides were detected of DCPA was about the same from incomplete and only includes use by in runoff from agricultural areas, and agricultural and urban areas. The main licensed pest control operators. 15 pesticides were detected in runoff from urban areas. Chlorpyrifos, 1 diazinon, DCPA, metolachlor, and 0.5 EXPLANATION 0.2 simazine were detected in almost every 0.1 sample. Median concentrations were 0.05 0.02 higher in runoff from urban areas for 0.01 PER LITER 0.005

IN MICROGRAMS 0.002 0.001 MEDIAN CONCENTRATION, 100

80

60

40 DETECTION IN PERCENT FREQUENCY, 20

0 EPTC DCPA Propanil Carbaryl Diazinon Trifluralin Simazine Malathion Prometon Disulfoton Benfluralin Metolachlor Chlorpyrifos

Sampling a storm drain during Napropamide PESTICIDE Pendimethalin February 1995 storm (photograph by Charles R. Kratzer, U.S. Geological More pesticides were detected, and generally in higher concentrations, in storm Survey). runoff from urban areas compared with storm runoff from agricultural areas.

U.S. Geological Survey Circular 1159 9 MAJOR ISSUES AND FINDINGS—DDT and Other Persistent Organochlorine Pesticides in Suspended Sediment, Bed Sediment, and Tissue of Biota

Organochlorine insecticides, such as Concentrations of organochlorine DDT in tissue (of clams and fish) and DDT and toxaphene, were used insecticides in aquatic organisms and in bed sediment, suggesting that extensively in the San Joaquin Valley bed sediment were highest in the small bioaccumulation was taking place to control agricultural pests. The use of western tributaries to the San Joaquin (Brown, 1997). such compounds was banned in the River and in the lower part of the San The results of these comparisons 1970s in the United States because of Joaquin River (Brown, 1997). Concen- indicate that, though these insecticide detrimental effects on wildlife, such as trations in these areas were still high concentrations might be declining, the and peregrine falcon. compared to national values from the they may adversely impact aquatic These chemicals are persistent in the 1970s and 1980s. Concentrations in organisms, and hence other wildlife, in environment because they degrade tissue and sediment at the west-side the San Joaquin Valley for years to slowly and are tightly bound to soil sites were among the highest encoun- come. An additional potential impact particles. Contaminated soils from tered at NAWQA Study Units. Com- of these compounds has been revealed agricultural and urban areas containing parison of 1992 data with data that by recent studies that suggest that these compounds are still entering were available for some sites showed organochlorine insecticides can be streams because of soil erosion. Once evidence of a decline in concentrations harmful to the hormone (endocrine) contaminated soil has entered a stream in tissue at those sites. Bed-sediment and immune systems of wildlife and as sediment, it becomes available to a concentrations appeared similar to humans at much lower concentrations variety of small aquatic organisms, historical data, but the historical data than was previously thought (Colborn such as insects that obtain food from were collected using different and Clement, 1992). the water or bed sediment. These methods, making direct comparisons organisms then are eaten by larger difficult. There was a strong EXPLANATION organisms, resulting in the contam- correlation between concentrations of EAST-SIDE SITESITES WEST-SIDE SITESITES inants being passed up the food chain San Joaquin River sites (3 sites) in processes known as bioaccumu- MUD AND SALT Compound Tissue Bed Sediment SLOUGH SITES lation. This process can result in SAN JOAQUIN concentrations of organochlorine Total DDT 50–510 ND–13 RIVER SITES compounds in fish and other biota that Toxaphene ND–160 ND are harmful to wildlife and humans Dieldrin ND–5 ND that consume them. Dacthal ND–33 ND PCBs ND–57 ND Concentrations of DDT and . ver Ri organochlorine insecticides West-side sites (3 sites) us la is an in aquatic organisms and bed Compound Tissue Bed Sediment St Sa sediment still exceed Total DDT 509–2,192 109–415 n guidelines for protection of Toxaphene ND–2,000 ND–630 Hospital r Creek ek Rive e fish-eating wildlife Dieldrin ND–10 1–10 r umne C Tuol m a J Dacthal 11–360 ND–32 r o g a Studies done during the 1970s and n q I k u PCBs ND–57 ND ee i 1980s documented contamination of Cr n to Permethrin NA ND–31 er both stream bed sediments and aquatic Pu el Olive Ave. Turlock Irrigation organisms in the San Joaquin River D Drain District Lateral 5 East-side sites (8 sites) Spanish system. In those studies, levels of Grant organochlorine insecticides in the San Compound Tissue Bed Sediment Drain er Joaquin Valley were high compared Merced Riv Total DDT 6–101 ND–50 k ee with other parts of the Nation, and Cr R iv Chlordane ND ND–9 ba e tim r levels in aquatic organisms exceeded res O Newman M u Wasteway L d S guidelines for the protection of fish- Mud and Salt Sloughs sites (2 sites) o a C l 0 5 MILES s t r B S S e eating wildlife in several areas (Brown, a l l e o o n k u u Compound Tissue Bed Sediment o g g 1997). In October 1992, samples of 0 5 KILOMETERS s h h tissue of aquatic organisms and fine- Total DDT 79–342 1–7 grained bed sediment were collected at Dieldrin ND–6 ND 18 sites and analyzed to determine The concentration and variety of organochlorine insecticides in tissue and bed sediment whether the distribution or were highest in west-side sites, intermediate in the San Joaquin River sites, and lowest in concentrations of organochlorine east-side sites. (Red values – exceeded guidelines for the protection of fish-eating wildlife insecticides had changed from the [National Academy of Sciences and National Academy of Engineering, 1973]. NA – not earlier studies. analyzed; tissue and sediment values in micrograms per kilogram, wet and dry weight, respectively; ND – not detected).

10 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 MAJOR ISSUES AND FINDINGS—DDT and Other Persistent Organochlorine Pesticides in Suspended Sediment, Bed Sediment, and Tissue of Biota

Large amounts of California USEPA USEPA Drinking sediment-bound DDT and Chronic Acute Water Newman IRRIGATION SEASON Criterion Criterion Standard other organochlorine Wasteway WINTER RUNOFF insecticides are trans- IRRIGATION SEASON Newman Detected ported from small west- Orestimba Wasteway Creek Not detected Orestimba side tributaries to the San Creek Spanish WINTER RUNOFF Joaquin River during Grant Drain Spanish Detected Grant Drain winter storms Olive Avenue Not detected Drain Olive Avenue Drain

NAWQA did studies on the Del Puerto Creek Del Puerto west-side tributaries and main SAMPLING SITE Creek Ingram stem of the San Joaquin River to Creek Ingram SAMPLING SITE Creek determine the processes con- Hospital Creek Hospital trolling transport of sediment- Creek San Joaquin bound pesticides. Samples of River San Joaquin suspended sediment were anal- River yzed for 15 organochlorine 0.010.1 1 10 100 1,000 10,000 insecticides to compare transport INSTANTANEOUS LOADS 0.00010.001 0.01 0.1 1 10 OF TOTAL DDT, CALCULATED WHOLE-WATER during the irrigation season (June IN GRAMS PER DAY CONCENTRATION OF TOXAPHENE, 1994) with transport during IN MICROGRAMS PER LITER winter storm runoff (January Loads of total DDT were substantially greater in Most whole-water concentrations of 1995) (Kratzer, 1998). samples collected during winter runoff compared toxaphene exceeded the USEPA The most frequently detected with samples collected during irrigation season chronic criterion for protection of organochlorine insecticides at all sites except Hospital Creek. freshwater aquatic life. during both the winter storm runoff drinking-water standards (California similar to irrigation season transport. and irrigation season were p,p´-DDE, Department of Water Resources, The average winter transport is also p,p´-DDT, p,p´-DDD, dieldrin, toxa- 1995). dependent on long-term seasonal phene, and chlordane. Aldrin, endrin, variations in suspended-sediment and mirex, and lindane also were detected Although controlling organochlorine insecticide concen- during the winter storm runoff; lindane irrigation-induced soil ero- trations, both of which are unknown. was also detected during the irrigation sion will reduce the transport Nevertheless, these findings indicate season. of organochlorine insecti- that runoff from winter storms will Median concentrations of total cides, it will not eliminate continue to deliver a significant load of DDT, chlordane, dieldrin, and toxa- organochlorine insecticides sediment-bound organochlorine phene on suspended sediment were insecticides to the San Joaquin River from the San Joaquin River slightly greater during the irrigation for an indeterminate amount of time, season than during winter storm run- because of transport during even if irrigation-induced soil erosion off. However, streamflows, suspended- winter storms is reduced. sediment concentrations, and instant- Estimated loads of aneous loads were substantially greater organochlorine insect- during the winter storm runoff. icides for the entire irriga- Most of the calculated whole-water tion season exceeded concentrations of p,p´-DDT, chlor- estimated loads for the dane, dieldrin, and toxaphene January 1995 storm by exceeded the USEPA chronic criteria about 2 to 4 times for for the protection of freshwater aquatic suspended transport and life (U.S. Environmental Protection about 3 to 11 times for Agency, 1986). In addition, 6 of 16 total transport. However, toxaphene and 1 of 16 p,p´-DDT because the average concentrations exceeded USEPA acute winter runoff is 2 to 4 criteria for the protection of freshwater times the runoff during aquatic life (U.S. Environ-mental the January 1995 storm, Protection Agency, 1986), and 5 of 16 average winter transport Orestimba Creek during a winter storm (left) and irrigation chlordane and 1 of 16 toxaphene of organochlorine season (right) (photographs by Sylvia V. Stork and Charles concentrations exceeded California insecticides may be R. Kratzer, U.S. Geological Survey, respectively).

U.S. Geological Survey Circular 1159 11 MAJOR ISSUES AND FINDINGS—Nutrients in the San Joaquin River

Nitrogen and phosphorus are Orestimba Creek in 15, 11, and 9 including subsurface agricultural essential nutrients for aquatic plants. percent, respectively, of samples drainage, runoff from fertilizer However, in high concentrations, they collected between April 1993 and applications, wastewater-treatment can cause excessive plant growth March 1995. However, these tribu- plant effluent, and runoff from dairies. (eutrophication) and toxicity to infants taries are not designated as drinking- The relative contribution of these (“blue baby syndrome” or methemo- water sources. The MCL was not sources was evaluated with estimates globinemia from ingestion of nitrate). exceeded during this period in the of nitrate loads and with trends in The USEPA has set criteria for the main stem of the San Joaquin River, a ammonia and phosphorus nitrate and ammonia forms of nitrogen, designated drinking-water source. concentrations. Wastewater- treatment but not for phosphorus. The maximum plant effluent and runoff from dairies contaminant level (MCL) for nitrate in Nitrate concentrations in the San Joaquin River have been have especially high concentrations of drinking water is 10 milligrams per ammonia and phosphorus, yet liter as nitrogen (mg/L as N) (U.S. increasing during the last 40 concentrations of ammonia and Environmental Protection Agency, years phosphorus in the San Joaquin River 1986). Increasing nitrate concentrations in generally declined or remained stable The USEPA also has established the San Joaquin River could be while nitrate concentrations steadily criteria for maximum ammonia con- attributed to several sources, increased. centrations in surface water on the basis of chronic and acute exposure of 121 15' 121 00' 37 aquatic organisms to un-ionized 45' ANNUAL NITRATE LOADS, IN r ammonia (U.S. Environmental Protec- ive TONS PER YEAR (AS N) s R au 1986 (wet year) tion Agency, 1986). These criteria vary sl Sacramento- ni ta 1988 (dry year) inversely with pH and temperature. S San Joaquin OVERLAP OF 1986 The chronic criteria range from about Delta AND 1988 0.2 to 2 mg/L as N for the range of pH 0 San Joaquin River (7.5–8.5) and temperatures (5–25°C) Modesto near Vernalis 1,000 generally found in surface water in the San Joaquin Valley. 2,000 er 3,000 k iv SAN JOAQUIN COCree R

Mud and Salt Sloughs pital Width of color bar

s Tons per year as N Ho ne 4,000 lum account for nearly half of the uo T 5,000 m a nitrate in the San Joaquin r k STUDY UNIT BOUNDARY g e n e I r SITE LOCATION River C S a n J Nutrient concentrations in the lower o a q u San Joaquin River are determined in R iv primarily by relatively concentrated e ek r inputs from west-side agricultural Cre to San Joaquin River er drainage, east-side wastewater- Pu el at Patterson D treatment plants and runoff from Turlock Irrigation District lateral 5 dairies, and relatively dilute inputs Spanish Grant Drain from major east-side tributaries. Mud and Salt sloughs receive a part of their STANISLAUS CO MERCED CO flow from subsurface drains that drain about 60,000 acres of agricultural land. k e re Although the sloughs account for only C a b m ver about 10 percent of the streamflow in i Ri t Merced s e the San Joaquin River near Vernalis, r O San Joaquin River the subsurface drainage is very high in near Newman nitrate (about 25 mg/L as N), and the sloughs contribute nearly one-half the nitrate (Kratzer and Shelton, in press). Newman Wasteway B The nitrate transported in the San ea L r S C o r a ee Joaquin River during a wet year (1986) s k n B J 37 a M n o was about 50 percent more than that a o u d S q 15' 0 5 MILES s a u S l transported in a dry year (1988). C t i l n r o S e R 0 5 KILOMETERS u l e o i g u v k h e The nitrate MCL was exceeded in g r h Spanish Grant Drain, Turlock STANISLAUSMERCED COCO During both dry and wet years, much of the nitrate load in the San Joaquin River can Irrigation District lateral 5, and be attributed to subsurface agricultural drainage discharged to Mud and Salt sloughs.

12 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 MAJOR ISSUES AND FINDINGS—Nutrients in the San Joaquin River

The source of the nitrate increase 3.2 TREND during the 1950s was indeterminate. USGS During the 1960s, runoff from ferti- STORET lizer applications (primarily in east- side basins) and subsurface agricul- tural drainage were the probable 1.6 sources of the increase. Since 1970, subsurface agricultural drainage has

been the primary cause of the FLOW-ADJUSTED increasing nitrate trend (Kratzer and Shelton, in press). Other studies have NITRATE CONCENTRATION, 0 IN MILLIGRAMS PER LITER, AS N determined that the nitrate in the sub- 1950 1960 1970 1980 1990 surface agricultural drainage primarily WATER YEAR comes from the leaching of native soil nitrogen and not from fertilizer appli- The flow-adjusted nitrate concentration in the San Joaquin River has increased from cation (Brown, 1975). Other sources of about 0.3 to 1.4 milligrams per liter (mg/L) over the last four decades. nitrate loads were especially important 8,000 in the early 1980s because of the effect ESTIMATED NITRATE LOADS IN SAN JOAQUIN RIVER NEAR VERNALIS of an extremely wet year (1983) on the (5-year running averages) 5-year running averages. The 6,000 unusually large inputs of nitrate in OTHER SOURCES SUBSURFACE AGRICULTURAL DRAINS 1983 were probably from (1) inflow 4,000 EAST-SIDE TRIBUTARIES from the Tulare Basin through the San Joaquin River , (2) discharge from total wastewater-treatment plants, (3) runoff 2,000 from dairies, and (4) runoff from fertilizer applications west of the San

Joaquin River (Kratzer and Shelton, in NITRATE, IN TONS PER YEAR, AS N 0 1950 1960 1970 1980 1990 press). Despite this long-term increase in the San Joaquin River, nitrate Nitrate loads in the San Joaquin River from subsurface agricultural drains have concentrations are still well below the increased steadily since the 1950s. USEPA drinking-water standard. exceeded the USEPA chronic criteria 2 0.20 Ammonia criteria were NITRATE in 2 of the 51 samples collected at the AMMONIA frequently exceeded in San Joaquin River at Patterson during 0.15 Turlock Irrigation District 1985–88. lateral 5 and occasionally Ammonia concentrations in Turlock exceeded in Orestimba Creek Irrigation District lateral 5, Orestimba 1 0.10 and Spanish Grant Drain Creek, and Spanish Grant Drain On the basis of monthly samples exceeded the USEPA chronic criteria 0.05 in 76, 14, and 5 percent, respectively, collected during 1985–88, ammonia FLOW-ADJUSTED NITRATE, FLOW-ADJUSTED AMMONIA, IN MILLIGRAMS PER LITER, AS N of samples collected between April IN MILLIGRAMS PER LITER, AS N concentrations in the San Joaquin 0 0 River increased from Newman to 1993 and March 1995. None of the 19701975 1980 1985 1990 Patterson, then declined from samples collected at the San Joaquin YEAR Patterson to Vernalis as a result of River at Patterson during April 1993 to dilution by the Tuolumne and Stanis- March 1995 had ammonia concentra- Nitrate concentration in the San laus Rivers (Kratzer and Shelton, in tions that exceeded the USEPA chronic Joaquin River have steadily increased criteria, but some concentrations were while ammonia concentration has press). The increase from Newman to declined since 1984. Patterson is attributed to relatively just under the criteria. concentrated inputs, such as Turlock Unlike nitrate, ammonia concentra- nitrate by improved wastewater Irrigation District lateral 5, Orestimba tions at the San Joaquin River near treatment, reduced discharges from Creek, and Spanish Grant Drain. Most Vernalis did not increase from 1974 to wastewater-treatment plants due to a of the flow in Turlock Irrigation 1990. Instead, ammonia concentra- sequence of dry years during the late District lateral 5 is effluent from the tions increased until 1984, then 1980s and expanded use of land Turlock wastewater-treatment plant, declined. This decrease was probably disposal, and reduced inputs from especially during the nonirrigation due to a combination of factors, dairies during the sequence of dry season. Ammonia concentrations including conversion of ammonia to years (Kratzer and Shelton, in press).

U.S. Geological Survey Circular 1159 13 MAJOR ISSUES AND FINDINGS—Fish Communities, Stream Habitat, and Water Quality in the San Joaquin River Drainage

Human activities, including devel- The 20 low-elevation sites were all River and on small western and opment of water resources, agriculture, in the lower San Joaquin River drain- southern streams. Specific and urbanization in the San Joaquin– age, downstream from the major foot- conductance (an indicator of salinity), Tulare Basins, have been accompa- hills reservoirs. Four groups of sites which was highest at these sites, is a nied by large-scale changes in aquatic were identified on the basis of fish good indicator of general water ecosystems. Populations of anadro- communities, water chemistry, and chemistry and of the influence of mous salmon have declined, along habitat quality: a San Joaquin Main irrigation return flows in the San with other migratory and resident Stem group, a Lower Tributary group, Joaquin River drainage. Fish native species. Though there are likely a Stanislaus River group, and an Upper cover—the percentage of area that many reasons for the decline, the roles Tributary group. provides cover from predators—was of water chemistry and habitat degra- The San Joaquin Main Stem group lowest at these sites. Environmental dation have not been assessed on a was characterized by high percentages degradation, as indicated by increased basin-wide scale. Fish communities of introduced species tolerant of harsh specific conductance and decreased were sampled in the San Joaquin– environmental conditions, particularly fish cover, was related to human Tulare Basins to determine their status the fathead minnow, red shiner, activities such as agricultural land use. and whether they provided useful indi- threadfin shad, and inland silverside The Lower Tributary group was cations of water chemistry and habitat (all referred to as the San Joaquin characterized by high percentages of conditions. Main Stem species). The San Joaquin introduced , redear Introduced fish species Main Stem group included eight sites sunfish, and white catfish. These sites outnumber native species on the main stem of the San Joaquin were located in the lower and middle almost 2 to 1, indicating Stanislaus River group Upper Tributary group impaired habitat or water 60 60 chemistry or both 40 40 Assessments of fish communities were made at 32 sites during August 20 20 and September from 1993 to 1995. 0 0

MEAN PERCENTAGE OF MAXIMUM VALUE SC CF AL MEAN PERCENTAGE OF MAXIMUM VALUE SC CF AL Fish were collected and identified to Habitat variables Fish communityHabitat variables Fish community species, and habitat and water- EXPLANATION chemistry data were collected at each site (Meador and others, 1993a,b). FISH TYPES r Knights Ferry Native species us Rive A total of 34 species of fish anisla Ripon St San Joaquin were collected. Twelve Riverbank Main Stem species species were native to Largemouth bass Modesto Waterford and sunfish California and 22 species Vernalis ne River Catfish S Tuolum were introduced from a n Smallmouth bass J er outside California. Native o iv a R q d Other introduced Patterson u ce species were generally in er species R M iv more abundant at higher e r SITE GROUPS elevation sites in the valley, the k San Joaquin e re Main Stem foothills, and the Sierra Nevada. C Merced Lower Tributary Introduced species were generally mba Oresti Gustine 0 5 10 MILES more abundant at lower elevation sites Stanislaus River on the valley floor. High percentages 0 5 10 KILOMETERS Upper Tributary of introduced species are considered an indication of impaired water chem- San Joaquin Main Stem group Lower Tributary group 60 60 istry and habitat conditions (Hughes and Gammon, 1987; Karr, 1991). 40 40 Using the fish data collected, groups 20 20 of sites with similar relative abun- dances of fish species were defined 0 0 MEAN PERCENTAGE OF MAXIMUM VALUE MEAN PERCENTAGE OF MAXIMUM VALUE SC CF AL SC CF AL using statistical techniques. This Habitat variablesFish community Habitat variables Fish community analysis was done twice: once for the 20 low-elevation sites most likely to be At the 20 lower elevation sites, fish communities, habitat, and water chemistry varied affected by human activities, and once significantly among the site groups. (SC – Specific conductance; CF – Cover for fish; for all of the 32 sites sampled. AL – Agricultural land).

14 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 MAJOR ISSUES AND FINDINGS—Fish Communities, Stream Habitat, and Water Quality in the San Joaquin River Drainage

reaches of the Merced and the San Joaquin main stem sites is Tuolumne Rivers, but only the consistent with these patterns. farthest downstream site on Environmental degradation due to the Stanislaus River. Values human activities may have been of specific conductance, fish stressful to resident fish as indicated by cover, and agricultural land the high incidence of external use were intermediate abnormalities, such as parasites and between the Upper Tributary lesions, at the Lower Tributary sites and San Joaquin Main Stem (21 percent) and San Joaquin main groups. stem sites (17 percent). The incidence The Upper Tributary of abnormalities was much lower at the Stanislaus River (3 percent) and Upper group included the farthest Riparian and instream habitats are good at Orestimba upstream site on the Stan- Creek, but because water chemistry is poor and Tributary sites (3 percent). In other islaus and Merced Rivers, fluctuations in flow are substantial, the site had a high areas of the country, an incidence of and the two farthest up- percentage of introduced fish species (photograph by external abnormalities greater than 2 stream sites on the Larry R. Brown, U.S. Geological Survey). percent is considered an indicator of Tuolumne River. These impaired conditions (Hughes and sites were characterized by high small, cold, high-elevation streams and Gammon, 1987; Karr, 1991). percentages of the native species: large, warm, low-elevation rivers. The rarity of native fishes at the Sacramento squawfish, hardhead, Thus, these groups are most indicative Lower Tributary and San Joaquin main Sacramento sucker, and prickly scul- of large-scale, natural gradients and stem sites may not be irreversible. pin. Specific conductance and agri- less related to environmental impair- High discharges in 1995 in the Merced cultural land use were lowest at these ment than the groups obtained from and Tuolumne Rivers were accompa- sites, and fish cover was highest. the analysis of 20 low-elevation sites. nied by higher percentages of resident The two middle sites on the Stanis- Native species are more and migratory native species. Statisti- laus River formed a separate group successful in the major cal analysis of data from sites sampled in more than one year indicated that characterized by high percentages of eastern tributaries when introduced smallmouth bass and native fish communities in 1993 and 1994 tule perch. Water chemistry and habitat flows are higher were very similar, but in 1995 were were similar to the Upper Tributary Overall environmental quality is very different from the other years. sites. reflected by fish communities: native Also, the greater abundance of native The second analysis, which was species are common at the least altered species in the Stanislaus River, particu- based on the fish data from all 32 sites, sites, and tolerant introduced species larly tule perch, at downstream sites also resulted in four groups of sites: a are common at the most altered sites. compared with the other eastern tribu- San Joaquin Main Stem group, a Foot- However, the influences of water taries, suggests that the higher summer hill group, a Lower Tributary group, chemistry and habitat on fish com- flows favor native species. Further and a Sierra Nevada group. The San munities could not be separated monitoring during different flow con- Joaquin Main Stem group was identi- because both sets of variables were ditions could help determine condi- cal and the Lower Tributary group very related to land use (Brown and others, tions necessary to reestablish native similar to the groups obtained using 20 in press). Additional variables may fish communities. sites. The Foothill group included all also contribute to this but one site in the previously defined pattern. Dissolved pesti- Upper Tributary group, the Stanislaus cide concentrations some- River group, and additional sites times reached levels toxic located upstream from the foothill res- to some invertebrates, ervoirs. These sites were characterized primarily at sites in the by native Sacramento squawfish, hard- San Joaquin Main Stem head, tule perch, scul-pins, and intro- group. Similarly, concen- duced smallmouth bass. The Sierra trations of organochlorine Nevada group was dominated by insecticides in sediments native rainbow trout and introduced and tissues of biota were brown trout. Water chemistry and habi- highest at sites in the San tat conditions were very different Joaquin Main Stem group among site groups, as would be (Brown, 1997). The This site on the Stanislaus River has good riparian expected in a study that included dominance of tolerant habitat, instream habitat, and water chemistry introduced species at (photograph by Larry R. Brown, U.S. Geological Survey).

U.S. Geological Survey Circular 1159 15 MAJOR ISSUES AND FINDINGS—Effect of Agriculture on Ground Water, Eastern San Joaquin Valley

Ground water is the source of drink- 100 the median in the regional aquifer sur- ing water for most of the population of 50 vey; therefore, some of the other land- the eastern San Joaquin Valley. Each 20 use settings in the eastern San Joaquin year, millions of pounds of nitrate (in Drinking- Valley must have generally lower 10 water fertilizer and manure) and pesticides standard nitrate concentrations than these three are applied to cropland. Some of these 5 agricultural settings. National chemicals infiltrate to the water table, 2 background levels Nitrate concentrations in degrade the water quality, and poten- 1 tially cause a public health risk. samples from shallow 0.5 domestic wells were related The quality of ground water in the 0.2 to nitrate application, alluvial fans of the eastern San Joaquin Valley was assessed by collecting data 0.1 sediment texture, and 0.05 potential for nitrate removal from three sets of wells: 30 domestic NITRATE, IN MILLIGRAMS PER LITER wells representative of the regional by chemical reactions 0.02 aquifer, 60 shallow domestic wells in 0.01 Sources of nitrate from agricul- three well-defined and contrasting RAS VIN ALM CAV ture—fertilizer and manure—were agricultural land-use settings, and 20 TYPE OF WELL estimated for a 0.25-mile-radius circle multilevel monitoring wells in a Nitrate concentrations in 24 percent of centered at each well in each of the 3.5-mile transect along a ground-water domestic wells exceeded USEPA three agricultural land-use settings. flow path (see p. 24–25). drinking-water standards (RAS – regional Nitrate concentrations in ground water aquifer survey; VIN – vineyard land use; in the three land-use settings were Nitrate concentrations in ALM – almond land use; CAV – corn, alfalfa, and vegetable land use). related to estimates of the amount of ground water in the eastern nitrogen applied: the greatest amount San Joaquin Valley often Nitrate concentrations in ground of nitrogen was applied in the almond exceeded the drinking-water water sampled during 1993–95 from land-use setting; a slightly lower standard shallow domestic wells (median well amount was applied in the corn, depth 150 feet) were compared among alfalfa, and vegetable land-use setting; Nitrate concentrations in 24 percent three contrasting agricultural land-use and the smallest amount was applied in (21 of 88) of the domestic wells sam- settings. These 60 wells (three sets of the vineyard land-use setting (Burow pled during 1993–95 in the regional 20) represent a part of the aquifer that and others, in press, a). The estimated aquifer survey and land-use studies of is usually used as a domestic water amount of nitrogen applied to individ- the eastern San Joaquin Valley supply. Nitrate concentrations were the ual sites was not strongly related to exceeded the drinking-water standard highest in samples from the wells in nitrate concentrations in ground-water of 10 mg/L established by the USEPA. the almond land-use setting, whereas samples from the wells, however. Furthermore, ground-water samples concentrations were the lowest in sam- These results indicate that estimates of from 77 percent of the wells had ples from wells in the vineyard land- the amount of nitrogen applied are a nitrate concentrations greater than use setting. Nitrate concentrations fair indicator of nitrate concentrations 2 mg/L, which is believed to represent were intermediate in samples from a for an area; however, the estimates are background concentrations (Mueller grouped land-use setting of corn, not a good predictor of concentration and Helsel, 1996). These findings indi- alfalfa, and vegetables. Median nitrate in an individual well. cate that ground-water quality has concentrations in the three land-use This lack of predictability probably been degraded over a large part of this settings were greater than or equal to is due to several factors. The amount aquifer because of the input of nitrate from human activity. Nitrate sources and aquifer susceptibility vary in the three agricultural land-use settings. Ground-water samples collected in Corn, Vine- 1995 from the 30 domestic wells in the Characteristic Almond alfalfa, veg- yard regional aquifer survey (median well etables depth 182 feet) had a median nitrate concentration of 4.6 mg/L; 5 of the 30 Median nitrate concentration, in milligrams per liter Low High Intermediate 4.6 10 6.2 wells (17 percent) exceeded the (number of samples that exceeded the USEPA drinking- water standard in parenthesis) (3) (8) (7) USEPA drinking-water standard. The Low High High median concentration of 4.6 mg/L was Source: nitrogen applied within a 0.25-mile radius 7,300 lb 19,900 lb 16,400 lb higher than the median of 2.4 mg/L for ground water in similar alluvial set- Susceptibility: sediment texture High High Low tings with agricultural land use nation- Susceptibility: potential for nitrate removal by chemical Intermedi- Low High wide (Mueller and others, 1995). reactions (nitrate reduction) ate

16 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 MAJOR ISSUES AND FINDINGS—Effect of Agriculture on Ground Water, Eastern San Joaquin Valley of coarse-grained sediments (sand- or nitrate concentrations. In contrast, nitrate concentrations. Data from wells gravel-sized) in the subsurface, which there is little evidence of nitrate reduc- in the eastern San Joaquin Valley that is referred to as sediment texture, is a tion in samples from the almond and were less than or equal to 200 feet major factor in the susceptibility of a vineyard land-use settings. Therefore, deep indicate that median nitrate con- site to nitrate contamination. The sedi- ground water in parts of the corn, centrations increased significantly ment texture influences the rates of alfalfa, and vegetable land-use setting from the 1950s to the 1960s, and from infiltration and ground-water flow in is less susceptible to nitrate contamina- the 1970s to the 1980s. From 1950 to the aquifer, which controls how rapidly tion than ground water in the other two 1980, the amount of nitrogen fertilizer water at the surface, with high nitrate land-use settings because nitrate may applied in the eastern San Joaquin Val- concentrations, can infiltrate the soil be removed by biochemical processes. ley counties increased from 114 to 745 and move downward to a well in the The presence of fine-grained sedi- million pounds per year, an increase of aquifer. The sediment textures in the ment textures and evidence of nitrate 554 percent. The number of dairies and almond and vineyard land-use settings reduction at some sites in the corn, other confined-animal feedlots, and were generally coarse-grained and alfalfa, and vegetable land-use setting hence manure production, also have conducive to rapid infiltration and are a result of its location on the lowest increased greatly during this period. ground-water flow. The sediment tex- parts of the eastern alluvial fans, near However, estimates indicate that nitro- ture in the corn, alfalfa, and vegetable the boundary between the alluvial fans gen fertilizer is the largest source of land-use setting was generally fine- and basin, where sediments were nitrate in the eastern San Joaquin Val- grained with abundant clay, resulting deposited by different sedimentary ley (Gronberg and others, in press). Of in slow rates of infiltration and ground- processes. As a result, sediment tex- course, this generalization may not be water flow. ture and chemical conditions in the the case for areas where the source These contrasts in sediment texture, corn, alfalfa, and vegetable land-use may be attributed to confined-animal considered along with the contrasts in setting are more variable than in the feedlots located close together. the amount of nitrogen applied, indi- almond and vineyard land-use settings. As indicated by a much smaller but cate that nitrate concentrations in This high variability makes it difficult better controlled data set, nitrate ground water were highest where high to generalize the conclusions from the concentrations increased over less than susceptibility and high amounts of overall data set to specific sites. nitrogen applied occurred together (the a decade. Of the 30 wells in the almond land-use setting); nitrate con- Nitrate concentrations in regional aquifer survey in the eastern centrations in ground water were low- ground water have increased San Joaquin Valley that were sampled est where the amount of nitrogen in the eastern San Joaquin in 1995, 23 also had been sampled during 1986–87. The median nitrate applied was low, even though the sus- Valley ceptibility was high (the vineyard land- concentration of this subset of 23 use setting); and nitrate concentrations Analyses of several thousand domestic wells increased from in ground water were intermediate ground-water samples were compiled 2.4 mg/L during 1986–87 to 4.8 mg/L where the amount of nitrogen applied from USGS and USEPA data bases to in 1995 (Burow and others, in was high, but the susceptibility was evaluate the long-term changes in press, b). The increase in low (the corn, alfalfa, and vegetable land-use setting) (Burow and others, in 7 1,000 press, a). DECADE, (666) NUMBER OF SAMPLES 6 ESTIMATED FERTILIZER USE 23 WELLS SAMPLED DURING Nitrate in ground water can also be 800 removed by biochemical reactions 1986-87 AND IN 1995 such as nitrate reduction, in which 600 nitrate is converted to nitrogen gas. 4 These biochemical reactions can hap- pen in ground water that has very low concentrations of dissolved oxygen. 400 The chemical traits that indicate a 2

potential for nitrate reduction, such as IN MILLIGRAMS PER LITER 200 low dissolved-oxygen concentrations IN MILLION POUNDS PER YEAR and high concentrations of iron and MEDIAN NITRATE CONCENTRATION, (618) (1,038) (1,010) (666) ESTIMATED NITROGEN FERTILIZER USE, manganese, existed in ground-water 0 0 samples from the corn, alfalfa, and 1950 1960 1970 1980 1990 2000 vegetable land-use setting. The few YEAR samples that have these chemical traits Fertilizer use and median nitrate concentration in ground water have generally do in fact have low or nondetectable increased over the past four decades.

U.S. Geological Survey Circular 1159 17 MAJOR ISSUES AND FINDINGS—Effect of Agriculture on Ground Water, Eastern San Joaquin Valley nitrate concentration is likely attributed to increased fertilizer use from 1950 to 1980. Analyses of samples from the 20 multilevel 0 monitoring wells in the 25 vineyard land-use setting 50 water table 1.3 <0.03 <0.03 2.8 2.6 indicated that nitrate 75 1989 1992 1992 3.0 1992 1986 1991 depth of concentrations have 100 <0.03 0.3 household NA 1979 generally increased over 125 <0.03 6.4 well 1956 1977 the last four decades. In 150 2.0 1970 0.03 0.29 addition to analyses for 0.86 1961 0.86 1954 175 NA 0.46 1963 nitrate and pesticides, the 200 1954 estimated date when the 225 <0.03 ground water sampled 250 <0.03 <0.03 <0.03 1947 1965 1940 from these wells was re- IN FEET DEPTH BELOW LAND SURFACE, NA 275 charged was determined EXPLANATION by measuring concentra- ESTIMATED CONCENTRATIONS OF NITRATE 0 4,000 FEET RECHARGE DATE Greater than 10 milligrams per liter tions of chlorofluoro- 0 1,000 METERS carbons (CFC). CFC 1990s 3 to 10 milligrams per liter concentrations in 1980s Less than 3 milligrams per liter samples from the deepest 1970s <0.03 DBCP CONCENTRATION, 1960s IN MICROGRAMS PER LITER wells indicate that the Pre-1960s 1947 ESTIMATED RECHARGE DATE deepest ground water Monitoring wells installed along the ground-water flow path in the vineyard land-use setting show had entered the aquifer that DBCP and nitrate concentrations generally are lowest in older water and are high but variable prior to 1960. Nitrate in the younger water (<, less than). concentrations in the Pesticides were detected in detected in 80 percent of the samples. pre-1960 water are generally less than 69 percent of the ground- Pesticides were detected least often (in 3 mg/L. In general, ground-water age water samples collected from 55 percent of samples) in ground- increases with depth below land domestic wells in the eastern water samples from wells in the corn, surface, whereas nitrate concentrations alfalfa, and vegetable land-use setting, San Joaquin Valley decrease with depth. The highest although the number of pesticide nitrate concentrations occur in shallow Pesticides were detected in 61 detections were not significantly ground water that was recharged of the 88 domestic wells sampled different among the three land-use during 1977 to 1992. Because typical during 1993–95 (69 percent), but settings. domestic well depths in the vicinity of 100 concentrations of most pesti- VINEYARD LAND USE the monitoring well transect are about cides were low—less than ALMOND LAND USE CORN, ALFALFA, AND VEGETABLE 90 to 130 feet below land surface, 0.1 µg/L. Although 25 pesticides 80 LAND USE these data suggest that nitrate were detected, only 5 pesticides REGIONAL AQUIFER SURVEY concentrations could increase in were detected in more than 60 domestic wells in the vineyard 10 percent of the samples: land-use setting. simazine, 1,2-dibromo-3- 40 Taken together, these studies offer chloropropane (DBCP), atrazine, compelling evidence that nitrate con- desethylatrazine (a 20 centrations in the ground water in the transformation product of eastern San Joaquin Valley have atrazine), and diuron. The DETECTION FREQUENCY, IN PERCENT 0 increased over the last four decades; greatest number of pesticides SIMAZINE ATRAZINE DIURON DBCP prediction of future change is problem- were detected in ground-water SELECTED PESTICIDE atic because of the decrease in the samples from wells in the Simazine, atrazine, diuron, and DBCP are the most common pesticides in the eastern San Joaquin amount of fertilizer application over vineyard land-use setting, where Valley, California (atrazine detections include the last decade. 17 different pesticides were desethylatrazine).

18 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 MAJOR ISSUES AND FINDINGS—Effect of Agriculture on Ground Water, Eastern San Joaquin Valley

The occurrence of DBCP and a concentration that exceeded a wells (less than 90 feet deep), atrazine simazine in the three agricultural land- USEPA drinking-water standard, (or desethylatrazine) was detected in use settings is generally consistent although only six of the pesticides five of the six shallow wells, and with the available information on the detected in ground water in the eastern DBCP was detected in four of the six use of these pesticides (Burow and oth- San Joaquin Valley have drinking- shallow wells. Although plausible ers, in press, a). In contrast, atrazine water standards. EDB was detected in explanations exist for the high DBCP and diuron detections were not consis- one ground-water sample. concentrations in young ground water, tent with their reported use, possibly current data are insufficient to confirm because of their application on rights- Pesticide concentrations in the source of the high DBCP of-way for weed control. domestic wells were consistent over time (1986–87 concentrations. These data suggest that The number of pesticide detections ground water from domestic wells in was related to characteristics that dic- to 1995) but were higher in the vineyard land-use setting would tate the relative susceptibility of monitoring wells near the likely continue to contain DBCP, ground water beneath the three land- water table than at greater simazine, and atrazine (or use settings. The greatest number of depths pesticide detections occurred in the desethylatrazine). Of the 30 domestic wells sampled as vineyard land-use setting. The number The number of pesticide detections is of pesticide detections per sample was part of the regional aquifer survey in similar during 1986–87 and 1995 correlated with the coarse-grained sed- 1995, 19 had been sampled for pesti- (red – concentration remained the same iment texture and dissolved-oxygen cides during 1986–87. Samples from or decreased; blue – concentration concentrations. Furthermore, samples both periods were tested for 21 increased; white – indeterminate; * – pesticides and 37 volatile organic estimated. <, less than; µg/L, from 15 of the 18 (83 percent) wells micrograms per liter) with nitrate concentrations exceeding compounds (VOC), but the laboratory the USEPA drinking-water standard methods of analyses were different for Pesticide 1986-87 1995 also contained at least one pesticide. In the two time periods. An increase from concentration concentration µ µ the vineyard land-use setting, concen- 13 pesticide detections during 1986– ( g/L) ( g/L) trations of DBCP and nitrate were pos- 87 to 23 pesticide detections in 1995 Atrazine <0.1 0.02 itively correlated, indicating that can be attributed to the use of an <0.1 0.056 ground-water samples with the high- analytical method that was 10 times 0.1 0.007 est nitrate concentrations also had the more sensitive than the method used <0.1 0.002 highest DBCP concentrations. during 1986–87 (Burow and others, in <0.1 0.12 press, b). If the data are adjusted to the 0.4 0.081 DBCP concentrations same level of sensitivity, the number of <0.1 0.003 exceeded the USEPA pesticide detections is similar for the 0.2 0.009 drinking-water standard in 20 two periods: 10 detections during Simazine <0.1 0.059 percent of the ground-water 1986–87 and 7 detections in 1995. 0.2 0.01 samples collected from Concentrations of pesticides generally were lower in 1995 than during <0.1 0.002 domestic wells in the eastern 1986–87. Although the number of 0.1 0.095 San Joaquin Valley wells resampled is small, and the age <0.1 0.006 Concentrations of DBCP, a soil of the sampled ground water has not 0.1 0.11 fumigant banned since 1977, exceeded been determined, there is no evidence <0.1 0.049 the USEPA drinking-water standard of that the pesticide concentrations or the 0.2 0.009 0.2 µg/L in 18 of the 88 (or 20 percent) number of pesticides detected during 0.1 <0.005 1986–87 increased in 1995. domestic wells sampled during 1993– 0.2 0.075 95. Ten of the DBCP samples that Analyses of samples from the 20 DBCP <3.0 1.1 exceeded the USEPA standards were multilevel monitoring wells in the 1,2-dichlo- 6.4 0.4 from wells in the vineyard land-use vineyard land-use setting show that ropropane setting, where DBCP was used to com- DBCP concentrations generally Prometon <0.1 0.008* bat nematodes. In contrast, DBCP was decreased with depth and were highly <0.1 0.004* not detected in any of the samples variable near the water table. Pesti- from the wells in the corn, alfalfa, and cides were detected most frequently Cyanazine <0.1 0.023 vegetable land-use setting. The soil near the water table in ground water EDB <0.2 0.55 fumigant 1,2-dibromoethane (also that was recharged after 1980. Dicamba 0.01 <0.035 called EDB or ethylene dibromide) Simazine was detected in all six 0.01 <0.035 was the only other pesticide detected at ground-water samples from shallow Dichlorprop 0.01 <0.032

U.S. Geological Survey Circular 1159 19 WATER-QUALITY CONDITIONS IN A NATIONAL CONTEXT—Stream-Water Quality

Seven major water-quality characteristics were evaluated for stream sites in each NAWQA Study Unit. Summary scores for each characteristic were computed for all sites that had adequate data. Scores for each site in the San Joaquin–Tulare Basins Study Unit were compared with scores for all sites sampled in the 20 NAWQA Study Units during 1992–95. Results are summarized by percentiles; higher percentile values generally indicate poorer quality compared with other NAWQA sites. Water-quality conditions at each site also are compared to established criteria for protection of aquatic life. Applicable criteria are limited to nutrients and pesticides in water and semivolatile organic compounds (SVOC), organochlorine pesticides, and PCBs in sediment. (Methods used to compute rankings and evaluate aquatic-life criteria are described by Gilliom and others, in press.)

STUDY AREA showing inset FISH COMMUNITY DEGRADATION River s au isl High percentages of fish at sites in the an St fixed-site network were nonnative, Sa n omnivores, diseased or deformed, or River umne tolerant of human-caused stream Tuol degradation. Disease or deformity

k J ee o includes external parasites, tumors, and Cr a q Turlock Irrigation rto u e in skeletal deformities. All sites received Pu District Lateral 5 el D the poorest score for percentage of non- native species and percentage of fish R River iv Merced with external anomalies. Fish commun- e r ities at all sites were scored as highly k M ee L u S Cr o d a a s lt degraded when compared with fish b C S im B rest l S O r a o l e o n u u e g communities at other sites across the o g k h h s Nation.

EXPLANATION Ranking of stream quality relative to all NAWQA stream sites — Darker colored STREAM HABITAT DEGRADATION circles generally indicate poorer quality. River s au Bold outline of circle indicates one or more isl Physical characteristics of streams can an aquatic life criteria were exceeded. St S have substantial effects on water an Greater than the 75th percentile River chemistry and aquatic life. On the basis (among the highest 25 percent e lumn of stream modification, bank erosion, of NAWQA stream sites) Tuo bank stability, and riparian vegetation ek density, sites in the Study Unit were re J Between the median and the 75th percentile C o to a Turlock Irrigation r q moderately to highly degraded when ue u District Lateral 5 P i el n D compared with other sites in the Nation. Between the 25th percentile and the median There are no standards or guidelines that R River iv Merced apply to stream habitat. e r Less than the 25th percentile k M ee L u S (among the lowest 25 percent Cr o d a a s lt b C S im B rest l S of NAWQA stream sites) O r a o l e o n u e u o g g k s h h

20 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 WATER-QUALITY CONDITIONS IN A NATIONAL CONTEXT—Stream-Water Quality

ORGANOCHLORINE PESTICIDES in water iver PESTICIDES and PCBs in R River us bed sediment and biological sla us ni sla Concentrations of dissolved ta tissue ni S ta S S pesticides in the Study Unit an S an iver were among the highest of all R Concentrations of River mne uolu umne NAWQA sites nationwide. T organochlorine chemicals Tuol in the Study Unit, For many pesticides, this k J ee o k r a ee Study Unit had the max- C q particularly DDT com- r J to u Turlock Irrigation C o er in to a Turlock Irrigation u District Lateral 5 er q imum concentration of all 20 P pounds and toxaphene, u u District Lateral 5 el P in D el Study Units. All sites were high in bed sediment D exceeded the aquatic-life R er and tissues of fish or clams. Riv R r iv Merced Rive criteria for at least one e iv Merced r Levels at some sites were e r pesticide at least 17 percent ek L M S M e u a among the highest in the k S Cr o d ee L u a s lt r o d a b C S C s l of the time. However, tim B S a t res l b C S O r m a o l Nation. sti B S o e l e r O r n u a o l e u e o o g g n u u k e drinking-water-quality s h h o g g k h h s standards were not exceeded.

TRACE ELEMENTS in bed NUTRIENTS in water River sediment River s au us sl sla Nutrient concentrations in ni ni ta a S Concentrations of trace St the Study Unit ranged from S Sa a n elements in bed sediment n very low to one of the River River ne generally were higher than e olum umn highest in the Nation. The Tu Tuol concentrations found in high concentrations occur at

ekJ other NAWQA Study k J re o ee o sites that are downstream C a Cr a to q Turlock Irrigation o q Turlock Irrigation er u Units. rt u from agricultural drainage u in District Lateral 5 ue in District Lateral 5 l P P e el D D or wastewater-treatment plant discharge. Ammonia R River R River concentrations exceeded iv Merced iv Merced e e r r guidelines for fish toxicity ek M k M re L u S e L u S C o d a re o d a ba l C l tim s t a s t at three sites in the Study es b C S C S Or B tim B l S res l S O r r a o l a o l o e o e n u n u u e u e Unit. o g o g g g k k s h h s h h

SEMIVOLATILE ORGANIC CONCLUSIONS River COMPOUNDS in bed us sla sediment ni The Study Unit is in poor condition compared with the ta S other 19 Study Units in the categories of fish com- Sa n Few SVOCs were detected River munities, PCBs, and organochlorines in streambed umne in the Study Unit. Those Tuol sediment and fish tissue, and pesticides in the water. detected were usually Several sites exceeded guidelines and criteria, and k J found at low concentra- ee o r a the occurrence of nonnative fish species and fish C q to u Turlock Irrigation er i tions, and values were low Pu n District Lateral 5 with external anomalies were especially high in the el compared with other sites D Study Unit. Stream habitat and nutrient in the Nation. Criteria for concentrations in water were close to the median for R ver protection of aquatic life iv ced Ri e Mer the 20 Study Units. Only the occurrence and r were not exceeded. ek M concentrations of SVOCs in sediment were low re L u S a C o d a mb s l resti S t O C B l relative to the other Study Units. o S r a l u o e n g u e o h g k s h

U.S. Geological Survey Circular 1159 21 WATER-QUALITY CONDITIONS IN A NATIONAL CONTEXT—Ground-Water Quality

Five major water-quality characteristics were evaluated for ground-water studies in each NAWQA Study Unit. Ground-water resources were divided into two categories: (1) drinking-water aquifers, and (2) shallow ground water underlying agricultural or urban areas. Summary scores were computed for each characteristic for all aquifers and shallow ground-water areas that had adequate data. Scores for each aquifer and shallow ground-water area in the San Joaquin-Tulare Basins Study Unit were compared with scores for all aquifers and shallow ground-water areas sampled in the 20 NAWQA Study Units during 1992–95. Results are summarized by percentiles; higher percentile values generally indicate poorer quality compared with other NAWQA ground-water studies. Water-quality conditions for each drinking-water aquifer also are compared with established drinking-water standards and criteria for protection of human health. (Methods used to compute rankings and evaluate standards and criteria are described by Gilliom and others, in press.)

RADON EXPLANATION REGIONAL AQUIFER SURVEY (RAS) Radon concentrations were (includes all land uses) relatively high when compared Unspecified land use ALM with other NAWQA Study Units. RAS No current water-quality Almonds land use (ALM) standards exist for this element. Vineyards land use (VIN) Corn, alfalfa, vegetables land use (CAV) CAV All of these land-use settings represent both shallow ground water areas and drinking-water aquifers. For national comparison purposes, these land-use settings were compared with the summary scores of VIN other drinking-water aquifers.

Ranking of ground-water quality relative to all NAWQA ground-water studies — Darker colored circles generally indicate poorer quality. Bold outline of circle indicates that one or more standards or criteria were NITRATE exceeded.

Nitrate concentrations in shallow Greater than the 75th percentile ground water from domestic (among the highest 25 percent ALM wells in agricultural areas were of NAWQA ground-water studies) RAS among the highest of all NAWQA Study Units. The water Between the median and the 75th percentile quality was different in areas with CAV different crops. Drinking-water Between the 25th percentile and the median standards were exceeded in 40 percent of the wells in the almond Less than the 25th percentile area, and in only 15 percent of (among the lowest 25 percent VIN wells in the vineyard area. of NAWQA ground-water studies)

22 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 WATER-QUALITY CONDITIONS IN A NATIONAL CONTEXT—Ground-Water Quality

PESTICIDES

Pesticides were detected in more than 50 percent of ground-water ALM samples in the Study Unit. All RAS aquifer areas sampled had levels above the national median for NAWQA studies, but were not CAV among the highest in the Nation. No drinking-water standards were exceeded, except for DBCP (see VOC results below). VIN

CONCLUSIONS DISSOLVED SOLIDS Ground-water quality in the San Joaquin– Concentrations of dissolved Tulare Basins is generally poor compared solids in the eastern alluvial fans with the other Study Units. Nitrate ALM generally were higher than the concentrations were higher than the RAS median for all NAWQA Study national median and frequently exceeded Units; however, dissolved solids drinking-water standards in all of the four in areas where corn, alfalfa, and areas sampled. Pesticides were fre- CAV vegetables are grown were among quently detected and the rate of detection the highest. The dissolved-solids was above the national median. No standard is for aesthetics— drinking-water standards were exceeded. appearance and smell—and The rate of detection for VOCs was high VIN though often exceeded, no health compared to the other Study Units threat is indicated. because of the frequent detection of DBCP. No drinking-water standards were exceeded except for DBCP, and in one sample, EDB.

VOLATILE ORGANIC COMPOUNDS

VOCs were detected in 27 percent of the wells overall, and the per- ALM cent detection in most of the areas RAS was greater than the median for all NAWQA Study Units. The high rate of VOC detection and CAV the exceedance of the drinking- water standard in 40 percent of the wells in the vineyard area are largely the result of the detection VIN of the banned soil fumigant DBCP.

U.S. Geological Survey Circular 1159 23 STUDY DESIGN AND DATA COLLECTION

Sampling sites were selected to represent major, large- EXPLANATION LAND USE STREAM scale contrasts in ecoregions, land use, and hydrogeology. Urban CHEMISTRY SITES Most of the data were collected in the predominantly agri- Agriculture Basic Rangeland cultural San Joaquin Valley because factors likely to impact Intensive Forest water quality are concentrated in this area. This focus was Synoptic Tundra consistent with the first two topics selected for study at the Other national level by the NAWQA Program: pesticides and nutrients. Studies were designed to provide multiple lines of evi- dence to describe water quality conditions (Gilliom and others, 1995). To this end, investigations of surface-water chemistry, contaminants in sediment and in tissues of aquatic organisms, and aquatic ecology took place at the same sites, if possible. The studies also were designed to provide infor- mation on water quality over a range of complementary temporal and geographic scales. The time scale of surface- water investigations varied from once-a-year, to once-a- month, to several times a day. The geographic scale of the ground-water investigations ranged from sampling 30 wells distributed over 2,000 square miles to sampling four wells within 200 feet. Each scale of study revealed relations between water quality and causal factors not apparent at 0 20 40 MILES larger or smaller scales. 0 20 40 KILOMETERS At all levels of study, relevant ancillary information, such as land use, soil and aquifer properties, fertilizer-use rate, Location of stream chemistry sites. and locations of dairies, was collected to help explain the and interpretation of specialized studies. In general, the chemical and ecological data. Detailed information, such as questions addressed by each study component became more change in streamflow during a winter storm or the timing of focused during each of the 3 years of intensive data use of a particular pesticide, was also used for both design collection (September 1992 to August 1995).

EXPLANATION PHYSIOGRAPHY GROUND-WATER Eastern CHEMISTRY SITES alluvial fans Regional Western Aquifer Survey alluvial fans Vineyard land use Sierra Nevada Almond land use Coast Ranges Corn, alfalfa, or vegetable land use Flow path

Flow Path Study Area

0 20 40 MILES

0 20 40 KILOMETERS

Location of steam ecology sites. Location of ground-water chemistry sites.

24 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 STUDY DESIGN AND DATA COLLECTION

SUMMARY OF DATA COLLECTION IN THE SAN JOAQUIN-TULARE BASINS STUDY UNIT, 1992–95

Study Number Sampling frequency What data were collected and Why Types of sites sampled component of sites and period Stream Chemistry Basic Fixed Sites Streamflow, nutrients, major chemical constituents, organic car- Representative of a variety of agri- 10 Monthly plus storms (BFS)—gen- bon, suspended sediment, water temperature, specific con- cultural land uses, and the basin eral water ductance, pH, and dissolved oxygen to describe outflow. Jan. 1993–Dec. 1994 chemistry concentrations and seasonal variations. Intensive Fixed In addition to the above constituents, approximately 83 dis- Subset of basic sites representing 4 twice weekly to monthly Sites (IFS)— solved pesticides to describe concentrations and seasonal contrasting physiographic Jan. 1993–Dec. 1993 pesticides variations. areas, and the basin outflow. Synoptic Streamflow, pesticides, water temperature, specific conduc- Basic sites and others representing 23 (low Once June 1994 sites—water tance, pH, and dissolved oxygen to describe concentrations agricultural and urban land flow) chemistry and spatial distributions. uses. Contaminants in Total PCBs, 32 organochlorine pesticides, 63 semivolatile Depositional zones of all basic and 17 Once Oct. 1992 bed sediments organic compounds, and 44 trace elements to determine intensive sites, plus additional occurrence and spatial distribution. synoptic sites. Contaminants in Total PCBs, 30 organochlorine pesticides, and 24 trace elements Same sites as for contaminants in 18 Once Oct.–Nov. 1992 aquatic biota were analyzed to determine occurrence and spatial distribu- bed sediment where tissue tion. Clams and whole fish for organic contaminants. Clams, could be collected. fish livers, or crayfish for trace elements. Stream Ecology Intensive assess- Assess communities of fish, macroinvertebrates, and algae at Subset of BFS (9 of 10) plus a site 3 3 reaches/site in 1995 ments each site; and quantitatively describe stream habitat for these in Yosemite National Park. 4 1 reach/year, 1993–95 organisms. 6 1 reach in 1993 Synoptic studies Similar to the above, one reach per site, for areal comparison of Subset of BFS plus others. 32 Once in either 1993 or habitat and community composition, nutrient samples col- 1994 lected. Ground-Water Chemistry Regional Aquifer Major chemical constituents, nutrients, 83 pesticides, 60 vola- Domestic wells in the eastern allu- 30 Once in 1995 Survey—east- tile organic compounds, and radon to determine occurrence vial fans, San Joaquin Valley. ern alluvial fans of these constituents in this region. Land-use Major chemical constituents, nutrients, 83 pesticides, 60 volatile Shallow domestic wells; 20 Once in 1995 effects—corn, organic compounds, and radon to describe the effects of agri- Shallow monitoring wells; 10 alfalfa, and veg- cultural land use on shallow ground water, eastern alluvial >50 percent corn, alfalfa, and veg- etable row fans. etables grown in rotation within crops a 0.25-mile radius. Land-use effects— Major chemical constituents, nutrients, 83 pesticides, 60 volatile Shallow domestic wells; 20 Once in 1994 almond organic compounds, and radon to describe the effects of agri- Shallow monitoring wells; 10 orchards cultural land use on shallow ground water, eastern alluvial >50 percent almond orchards fans. within 0.25 mile radius. Land-use Major chemical constituents, nutrients, 83 pesticides, 60 volatile Shallow domestic wells; 20 Once in 1993 effects—vine- organic compounds, and radon to describe the effects of agri- Shallow monitoring wells; 10 yards cultural land use on shallow ground water, eastern alluvial >50 percent vineyards within fans. 0.25-mile radius. Chemical and Major chemical constituents, nutrients, 83 pesticides, 60 volatile 20 wells at 6 sites along an 20 Once in 1994 physical pro- organic compounds, radon, transformation products of 1,2- approximate ground-water flow Once in 1995 cesses along dibromo-3-chloropropane, and constituents used to estimate path beneath vineyard land use ground-water date when ground water was recharged. in eastern alluvial fan, San flow paths Joaquin Valley. Special Studies Dissolved pesti- Dissolved pesticides and streamflow were measured along with 2 IFS, 3 western valley sites, and 6 Jan.–Feb. 1993 cide transport in a dye traveltime study to assess the variability of concentra- basin outflow. winter storms tions during storms and the impact on the basin outflow. Spe- 5 eastern valley sites, 3 agricul- 9 Jan.–Feb. 1994 cific agricultural and urban areas were assessed. tural drains, and basin outflow. 5 urban sites, 3 agricultural drains, 16 Feb.–Mar. 1995 7 eastern valley sites, and basin outflow. Transport of sedi- Sediment-bound pesticides, dissolved pesticide, suspended sed- 2 Coast Ranges sites, 2 agricul- 8 June 1994 ment-bound iment, and streamflow to compare winter and irrigation sea- tural drains, 7 western valley 12 Jan. 1995 pesticides son transport. sites, and basin outflow. Aquatic ecology–- Assessment of algal community, chlorophyll-a and ash-free dry Synoptic sites. 8 Sept. 1995 Merced River, mass, and supporting data on nutrients, major constituents, Yosemite trace elements, and organic contaminants in bed sediment National Park and tissue.

U.S. Geological Survey Circular 1159 25 SUMMARY OF COMPOUND DETECTIONS AND CONCENTRATIONS—Analysis And Detection of Pesticides, Volatile Organic Compounds, and Nutrients in Ground and Surface Waters of the San Joaquin–Tulare Basins Study Unit

The following tables summarize data collected for NAWQA studies from 1992–95 by showing results for the San Joaquin– Tulare Basins Study Unit compared to the NAWQA national range for each compound detected. The data were collected at a wide variety of places and times. In order to represent the wide concentration ranges observed among Study Units, logarithmic scales are used to emphasize the general magnitude of concentrations (such as 10, 100, or 1000), rather than the precise number. The complete dataset used to construct these tables is available upon request.

Concentrations of herbicides, insecticides, volatile organic compounds, and nutrients detected in ground and surface waters of the San Joaquin–Tulare Basins Study Unit. [mg/L, milligrams per liter; µg/L, micrograms per liter; pCi/L, picocuries per liter; %, percent; <, less than; - -, not measured; trade names may vary]

a EXPLANATION Freshwater-chronic criterion for the protection of aquatic life Drinking water standard or guideline a Range of surface-water detections in all 20 Study Units Range of ground-water detections in all 20 Study Units Detection in the San Joaquin–Tulare Basins Study Unit

Herbicide Rate Concentration, in µg/L Herbicide Rate Concentration, in µg/L (Trade or common of (Trade or common of name) detec- 0.001 0.01 0.1 1 10 100 1,000 name) detec- 0.001 0.01 0.1 1 10 100 1,000 tion b tion b Alachlor (Lasso) 9% Ethalfluralin (Son- 13% 0% alan, Sonalen) <1% 2,6-Diethylaniline <1% Linuron (Lorox, <1% (Alachlor metabolite) 0% Linex, Sarclex) 0% Atrazine (AAtrex, 27% MCPA (Agritox, 3% Gesaprim) 7% Agroxone) 0% Deethylatrazinec <1% Metolachlor (Dual, 44% 1% (Atrazine metabolite) 7% Pennant) Benfluralin (Balan, 2% Metribuzin (Lexone, 3% Benefin, Bonalan) 0% Sencor) 0% Bromacil (Hyvar X, 8% Molinate (Ordram) 9% Urox B, Bromax) 0% 0% Butylate (Sutan, 4% Napropamide 24% Genate Plus, butilate) <1% (Devrinol) 1% Cyanazine (Bladex, 34% Norflurazon (Evital, 8% Fortrol) 1% Solicam, Telok) 2% 2,4-D (2,4-PA) 12% Oryzalin (Surflan, 8% 0% Dirimal, Ryzelan) 0% 2,4-DB (Butyrac, 1% Pebulate (Tillam) 11% Embutox) 0% 0% DCPA (Dacthal, chlo- 22% Pendimethalin 4% rthal-dimethyl) <1% (Prowl, Stomp) 0% Dichlorprop (2,4-DP, 3% Prometon (Gesa- 3% Seritox 50, Kildip) 0% gram, prometone) 1% Dinoseb (DNBP, DN 0% Pronamide (Kerb, 3% 289, Premerge) 2% propyzamid) 0% Diuron (Karmex, 54% Propachlor (Ramrod, <1% Direx, DCMU) 12% propachlore) 0% EPTC (Eptam) 43% Propanil (Stampede, <1% 1% Surcopur) 0%

26 Water Quality in the San Joaquin–Tulare Basins, 1992–95 SUMMARY OF COMPOUND DETECTIONS AND CONCENTRATIONS—Analysis And Detection of Pesticides, Volatile Organic Compounds, and Nutrients in Ground and Surface Waters of the San Joaquin–Tulare Basins Study Unit

Herbicide Rate Concentration, in µg/L Insecticide Rate Concentration, in µg/L (Trade or common of (Trade or common of name) detec- 0.001 0.01 0.1 1 10 100 1,000 name) detec- 0.001 0.01 0.1 1 10 100 1,000 tion b tion b

Simazine (Aquazine, 95% Methomyl (Lannate, 5% Princep, GEsatop) 34% Nudrin) 0% Tebuthiuron (Spike, 2% Methyl parathion <1% Perflan) 0% (Penncap-M) 0% Terbacilc (Sinbar) <1% cis-Permethrinc <1% 1% (Ambush, Pounce) 0% Thiobencarb (Bolero, 2% Propargite (Comite, 20% Saturn, benthiocarb) 0% Omite, BPPS) 0% Triallate (Far-Go) <1% Terbufos (Counter) <1% <1% 0% Triclopyr (Garlon, 1% Grazon, Crossbow) 0% Trifluralin (Treflan, 30% Trinin, Elancolan) <1%

Insecticide Rate Concentration, in µg/L Volatile organic Rate Concentration, in µg/L (Trade or common of compound of name) detec- 0.001 0.01 0.1 1 10 100 1,000 (Trade or common detec- 0.01 0.1 1 10 100 1,000 tion b name) tion b Aldicarbc (Temik) 1% 1,2,3-Trichloropro- -- 0% pane (Allyl trichloride) 7% Azinphos-methylc 12% 1,2,4-Trimethylben- -- (Guthion, Gusathion) 0% zene (Pseudocumene) 2% Carbarylc (Sevin, 25% 1,2-Dibromo-3-chlo- -- Savit) 1% ropropaned (DBCP) 21% Carbofuranc 5% 1,2-Dibromoethaned -- (Furadan, Curaterr) 0% (EDB) 1% Chlorpyrifos (Durs- 52% 1,2-Dichloropropane -- ban, Lorsban) <1% (Propylene dichloride) 6% p,p’-DDE (p,p’-DDT 14% Dichloromethane -- metabolite) <1% (Methylene chloride) 1% Diazinon 71% Methylbenzene (Tolu- -- <1% ene) 2% Dieldrin (Panoram D- 10% total Trihalomethanes -- 31, Octalox) 1% 2% Disulfotonc (Disys- <1% Trichloroethene -- ton, Dithiosystox) 0% (TCE) 2% Ethoprop (Mocap, <1% Trichlorofluoromethane -- Prophos) <1% (CFC 11) 2% Fonofos (Dyfonate) 10% 0% alpha-HCH (alpha- 4% Volatile organic Rate Concentration, in µg/L BHC, alpha-lindane) 0% compound of (Trade or common detec- 0.01 0.1 1 10 100 1,000 10,000 100,000 gamma-HCH 4% name) tion b 0% Tetrachloroethene -- Malathion (maldison, 8% (Perchloroethene) 3% malathon, Cythion) 1%

U.S. Geological Survey Circular 1159 27 SUMMARY OF COMPOUND DETECTIONS AND CONCENTRATIONS—Analysis And Detection of Pesticides, Volatile Organic Compounds, and Nutrients in Ground and Surface Waters of the San Joaquin–Tulare Basins Study Unit

Nutrient Rate Concentration, in mg/L Other Rate Concentration, in pCi/L (Trade or common of of name) detec- 0.01 0.1 1 10 100 1,000 10,000 100,000 detec- 1 10 100 1,000 10,000 100,000 tion b tion b Dissolved ammonia 94% Radon 222 -- 56% 100% Dissolved ammonia plus organic nitrogen 77% as nitrogen 6% Dissolved phospho- 96% rus as phosphorus 85% Dissolved nitrite plus 95% nitrate 97%

Herbicides, insecticides, volatile organic compounds, and nutrients not detected in ground and surface waters of the San Joaquin–Tulare Basins Study Unit.

Herbicides Insecticides 1,1-Dichloroethane (Eth- Bromochloromethane cis-1,3-Dichloropropene ylidene dichloride) (Methylene chlorobromide) ((Z)-1,3-Dichloropropene) 2,4,5-T 3-Hydroxycarbofuran (Carbofuran metabolite) 1,1-Dichloroethene Bromomethane n-Butylbenzene 2,4,5-TP (Silvex, Feno- (Vinylidene chloride) (Methyl bromide) (1-Phenylbutane) prop) Aldicarb sulfone (Standak, aldoxycarb, aldicarb metab- 1,1-Dichloropropene Chlorobenzene n-Propylbenzene Acetochlor (Harness Plus, (Monochlorobenzene) (Isocumene) Surpass) olite) 1,2,3-Trichlorobenzene Aldicarb sulfoxide (Aldi- (1,2,3-TCB) Chloroethane p-Isopropyltoluene Acifluorfen (Blazer, Tackle (Ethyl chloride) (p-Cymene) 2S) carb metabolite) 1,2,4-Trichlorobenzene Methiocarb (Slug-Geta, 1,2-Dichlorobenzene Chloroethene sec-Butylbenzene Bentazon (Basagran, Ben- (Vinyl chloride) tazone, Bendioxide) Grandslam, Mesurol) (o-Dichlorobenzene, tert-Butylbenzene Oxamyl (Vydate L, Pratt) 1,2-DCB) Chloromethane trans-1,2-Dichloroethene Bromoxynil (Buctril, Bro- (Methyl chloride) minal) Parathion (Roethyl-P, Alk- 1,2-Dichloroethane (Ethyl- ((E)-1,2-Dichlorothene) ron, Panthion, Phoskil) ene dichloride) Dibromomethane trans-1,3-Dichloropropene Chloramben (Amiben, (Methylene dibromide) Amilon-WP, Vegiben) Phorate (Thimet, Granu- 1,3,5-Trimethylbenzene ((E)-1,3-Dichloropropene) tox, Geomet, Rampart) (Mesitylene) Dichlorodifluoromethane Clopyralid (Stinger, Lon- (CFC 12, Freon 12) trel, Reclaim, Transline) Propoxur (Baygon, Blat- 1,3-Dichlorobenzene Nutrients tanex, Unden, Proprotox) (m-Dichlorobenzene) Dimethylbenzenes Dacthal mono-acid (Xylenes (total)) No nondetects (Dacthal metabolite) 1,3-Dichloropropane (Trimethylene dichloride) Ethenylbenzene (Styrene) Dicamba (Banvel, Dianat, Volatile organic Scotts Proturf) compounds 1,4-Dichlorobenzene Ethylbenzene (p-Dichlorobenzene, (Phenylethane) Fenuron (Fenulon, Feni- 1,1,1,2-Tetrachloroethane 1,4-DCB) dim) Hexachlorobutadiene (1,1,1,2-TeCA) 1-Chloro-2-methylbenzene Fluometuron (Flo-Met, Isopropylbenzene 1,1,1-Trichloroethane (o-Chlorotoluene) (Cumene) Cotoran, Cottonex, Metu- (Methylchloroform) ron) 1-Chloro-4-methylbenzene Methyl tert-butyl ethere 1,1,2,2-Tetrachloroethane (p-Chlorotoluene) MCPB (Thistrol) (MTBE) 1,1,2-Trichloro-1,2,2-triflu- 2,2-Dichloropropane Neburon (Neburea, Neb- Naphthalene oroethane (Freon 113, CFC Benzene uryl, Noruben) 113) Tetrachloromethane Picloram (Grazon, Tordon) Bromobenzene (Carbon tetrachloride) 1,1,2-Trichloroethane (Phenyl bromide) Propham (Tuberite) (Vinyl trichloride) cis-1,2-Dichloroethene ((Z)-1,2-Dichloroethene)

28 Water Quality in the San Joaquin–Tulare Basins, 1992–95 SUMMARY OF COMPOUND DETECTIONS AND CONCENTRATIONS—Analysis And Detection of Pesticides, Volatile Organic Compounds, and Nutrients in Ground and Surface Waters of the San Joaquin–Tulare Basins Study Unit

Concentrations of semivolatile organic compounds, organochlorine compounds, and trace elements detected in fish and clam tissue and bed sediment of the San Joaquin–Tulare Basins Study Unit. [µg/g, micrograms per gram, in dry weight; µg/kg, micrograms per kilogram, in dry weight for semivolatile organic compounds and organochlorine compounds in bed sediment, and in wet weight for organochlorine compounds in fish and clam tissue; %, percent; <, less than; - -, not measured; trade names may vary]

f EXPLANATION Guideline for the protection of aquatic life

Range of detections in fish and clam tissue in all 20 Study Units Range of detections in bed sediment in all 20 Study Units Detection in bed sediment or fish tissue in the San Joaquin–Tulare Basins Study Unit Detection in clam tissue in the San Joaquin–Tulare Basins Study Unit

Semivolatile organic Rate of Concentration, in µg/kg Semivolatile organic Rate of Concentration, in µg/kg compound detec- compound detec- tion b 0.11 10 100 1,000 10,000 100,000 tion b 0.11 10 100 1,000 10,000 100,000

1-Methylphenan- -- Di- n -octylphthalate -- threne 6% 6% 1-Methylpyrene -- Dibenz[ a,h ] -- 6% anthracene 6% 2,6-Dimethylnaphtha- -- Diethylphthalate -- lene 78% 17% 2,6-Dinitrotoluene -- Fluoranthene -- 6% 35% 2-Methylanthracene -- Indeno[1,2,3- cd ] -- 6% pyrene 11% 4,5-Methyle- -- Phenanthrene -- nephenanthrene 11% 33% 9H-Carbazole -- Phenol -- 6% 56% 9H-Fluorene -- Pyrene -- 6% 35% Acridine -- bis(2-Ethyl- -- 6% hexyl)phthalate 94% Anthracene -- p-Cresol -- 17% 28% Anthraquinone -- 6% Benz[ a ]anthracene -- Organochlorine Rate Concentration, in µg/kg 28% compound of (Trade name) detec- Benzo[ a ]pyrene -- 0.01 0.1 1 10 100 1,000 10,000 100,000 tion b 17% Benzo[ b ]fluoran- -- total-Chlordane 0% thene 33% 6% Benzo[ k ]fluoran- -- DCPA (dacthal, chlo- 28% thene 33% rthal-dimethyl) 6% Butylbenzylphthalate -- p,p’-DDE 89% 28% 72% Chrysene -- total-DDT 89% 33% 72% Di- n -butylphthalate -- Dieldrin (Panoram D- 17% 78% 31, Octalox) 17%

U.S. Geological Survey Circular 1159 29 SUMMARY OF COMPOUND DETECTIONS AND CONCENTRATIONS—Analysis And Detection of Pesticides, Volatile Organic Compounds, and Nutrients in Ground and Surface Waters of the San Joaquin–Tulare Basins Study Unit

Organochlorine Rate Concentration, in µg/kg Trace element Rate Concentration, in µg/g compound of of detec- detec- 0.01 0.1 1 10 100 1,000 10,000 (Trade name) 0.01 0.1 1 10 100 1,000 10,000 100,000 tion b tion b

PCB, total 11% Arsenic 94% 0% 100% cis-Permethrin -- Cadmium 62% (Ambush, Pounce) 6% 56% trans-Permethrin -- Chromium 94% (Ambush, Pounce) 6% 100% Toxaphene (cam- 11% Copper 100% phechlor) 6% 100% Lead 38% 100% Mercury 69% 100% Nickel 88% 100% Selenium 75% 100% Zinc 100% 100%

30 Water Quality in the San Joaquin–Tulare Basins, 1992–95 SUMMARY OF COMPOUND DETECTIONS AND CONCENTRATIONS—Analysis And Detection of Pesticides, Volatile Organic Compounds, and Nutrients in Ground and Surface Waters of the San Joaquin–Tulare Basins Study Unit

Semivolatile organic compounds, organochlorine compounds, and trace elements not detected in fish and clam tissue and bed sediment of the San Joaquin–Tulare Basins Study Unit.

Semivolatile organic 4-Chloro-3-methylphenol Organochlorine beta-HCH (beta-BHC, Trace elements compounds compounds beta-hexachlorocyclohex- 4-Chlorophenyl-phe- No nondetects nylether ane, alpha-benzene 1,2,4-Trichlorobenzene Aldrin (HHDN, Octalene) hexachloride) 1,2-Dichlorobenzene (o- Acenaphthene Chloroneb (chloronebe, delta-HCH (delta-BHC, Dichlorobenzene, 1,2- Acenaphthylene Demosan, Soil Fungicide delta-hexachlorocyclohex- DCB) 1823) Azobenzene ane, delta-benzene 1,2-Dimethylnaphthalene Benzo [c] cinnoline Endosulfan I (alpha- hexachloride) 1,3-Dichlorobenzene (m- Endosulfan, Thiodan, Benzo [g,h,i] perylene Dichlorobenzene) Cyclodan, Beosit, Malix, gamma-HCH (Lindane, C8-Alkylphenol gamma-BHC, Gammex- 1,4-Dichlorobenzene (p- Thimul, Thifor) ane, Gexane, Soprocide, Dichlorobenzene, 1,4- Dibenzothiophene Endrin (Endrine) gamma-hexachlorocyclo- DCB) Dimethylphthalate Heptachlor epoxide (Hep- hexane, gamma-benzene 1,6-Dimethylnaphthalene Isophorone tachlor metabolite) hexachloride, gamma-ben- 1-Methyl-9H-fluorene Isoquinoline Heptachlor (Heptachlore, zene) Velsicol 104) 2,2-Biquinoline N-Nitrosodi-n-propylamine o,p’-Methoxychlor 2,3,6-Trimethylnaphtha- Hexachlorobenzene (HCB) N-Nitrosodiphenylamine p,p’-Methoxychlor (Mar- lene Isodrin (Isodrine, Com- Naphthalene late, methoxychlore) 2,4-Dinitrotoluene pound 711) 2-Chloronaphthalene Nitrobenzene Mirex (Dechlorane) 2-Chlorophenol Pentachloronitrobenzene Pentachloroanisole (PCA, 2-Ethylnaphthalene Phenanthridine pentachlorophenol metabo- lite) 3,5-Dimethylphenol Quinoline 4-Bromophenyl-phe- bis (2-Chloroethoxy)meth- alpha-HCH (alpha-BHC, nylether ane alpha-lindane, alpha- hexachlorocyclohexane, alpha-benzene hexachlo- ride)

a Selected water-quality standards and guidelines (Gilliom and others, in press). b Rates of detection are based on the number of analyses and detections in the Study Unit, not on national data. Rates of detection for herbicides and insecticides were computed by only counting detections equal to or greater than 0.01 µg/L in order to facilitate equal comparisons among compounds, which had widely varying detection limits. For herbicides and insecticides, a detection rate of “<1%” means that all detections are less than 0.01 µg/L, or the detection rate rounds to less than one percent. For other compound groups, all detections were counted and minimum detection limits for most compounds were similar to the lower end of the national ranges shown. Method detection limits for all compounds in these tables are summarized in (Gilliom and others, in press). c Detections of these compounds are reliable, but concentrations are determined with greater uncertainty than for the other compounds and are reported as estimated values (Zaugg and others, 1995). d In the San Joaquin–Tulare Basins Study Unit, 152 ground-water samples were analyzed for 1,2-dibromo-3-chloropropane (DBCP) and 1,2-dibromoethane (EDB) at lower detection limits (0.03 and 0.04 µg/L, respectively). DBCP was detected in 50 of these samples and EDB was detected in one sample.

e The guideline for methyl tert-butyl ether is between 20 and 40 µg/L; if the tentative cancer classification C is accepted, the lifetime health advisory will be 20 µg/L (Gilliom and others, in press). f Selected sediment-quality guidelines (Gilliom and others, in press). (These tables were designed and built by Sarah Ryker, Jonathan Scott, and Alan Haggland.)

U.S. Geological Survey Circular 1159 31 REFERENCES

Brown, R.L., 1975, The occurrence Water Resources Bulletin 132-91, Oregon: Transactions of the and removal of nitrogen in 370 p. American Fisheries Society, subsurface agricultural drainage ———1995, Compilation of federal v. 116, p. 196-209. from the San Joaquin Valley, and state drinking water standards Karr, J.R., 1991, Biological California: Water Research, v. 9, and criteria: [Sacramento, Calif.], integrity—A long neglected no. 5/6, p. 529–546. Division of Local Assistance, aspect of water resource manage- Brown, L.R., 1997, Concentrations of Quality Assurance Technical ment: Ecological Applications, chlorinated organic compounds in Document series, no. 3, 56 p. v. 1, p. 66–84. biota and bed sediment in streams Colborn, Theo, and Clement, Coralie, Kratzer, C.R., 1997, Transport of of the San Joaquin Valley, (eds.), 1992, Chemically-induced diazinon in the San Joaquin River California: Archives of alterations in sexual and Basin, California: U.S. Environmental Contamination functional development—The Geological Survey Open-File and Toxicology, v. 33, no. 4, p. wildlife/human connection: Report 97-411, 22 p. 357–368. Princeton, N.J., Princeton Brown, L.R., Kratzer, C.R., and Scientific Publishing, Advances ———1998, Transport of sediment- Dubrovsky, N.M., in press, in Modern Environmental bound organochlorine pesticides Integrating chemical, water Toxicology series, v. 21, 403 p. to the San Joaquin River, California: U.S. Geological quality, habitat and fish Domagalski, J.L., Dubrovsky, N.M., Survey Open-File Report 97-655, assemblage data from the San and Kratzer, C.R., 1997, 30 p. Joaquin River drainage, Pesticides in the San Joaquin California, in Smith, C.S., and River, California—Inputs from Kratzer, C.R., in press, Pesticides in Scow, K., eds., Integrated dormant sprayed orchards: storm runoff from agricultural Assessment of Ecosystem Health: Journal of Environmental Quality, and urban areas in the Tuolumne Ann Arbor, Mich., Ann Arbor v. 26, no. 2, p. 454–465. River Basin in the vicinity of Press. Gilliom, R.J., Alley, W.M., and Gurtz, Modesto, California: U.S. Burow, K.R., Shelton, J.L., and M.E., 1995, Design of the Geological Survey Water- Dubrovsky, N.M., in press, a, National Water-Quality Resources Investigations Report Occurrence of nitrate and pesti- Assessment Program— 98-4017. cides in ground water beneath Kratzer, C.R., and Biagtan, R.N., three agricultural land-use Occurrence and distribution of 1997, Determination of travel- settings in the eastern San water-quality conditions: U.S. times in the lower San Joaquin Joaquin Valley, California, Geological Survey Circular 1112, River Basin, California, from 1993–1995: U.S. Geological 33 p. dye-tracer studies during 1994– Survey Water Resources Gilliom, R.J., Mueller, D.K., and 1995: U.S. Geological Survey Investigations Report 97-4284. Nowell, L.H., in press, Methods Water-Resources Investigations Burow, K.R., Stork, S.V., and for comparing water quality Report 97-4018, 20 p. Dubrovsky, N.M., in press, b, conditions among National Nitrate and pesticides in ground Water-Quality Assessment Study Kratzer, C.R., and Shelton, J.L., in water in the eastern San Joaquin Units, 1992-1995: U.S. press, Water-quality assessment Valley, California: Occurrence Geological Survey Open-File of the San Joaquin-Tulare Basins, and trends: U.S. Geological Report 97-589. California: Analysis of available Survey Water Resources Gronberg, J.M., Dubrovsky, N.M., data on nutrients and suspended Investigations Report 98-4040. Kratzer, C.R., Domagalski, J.L., sediment in surface water, 1972– California Department of Pesticide Brown, L.R., and Burow, K.R., in 1990: U.S. Geological Survey Regulation, [1994], Pesticides use press, Environmental setting of Professional Paper 1587, 94 p. data for 1993. (Digital data for the San Joaquin-Tulare Basins, Kuivila, K.M., and Foe, C.G., 1995, review at the California California: U.S. Geological Concentrations, transport and Department of Pesticide Survey Water-Resources biological effects of dormant Regulation, Sacramento, Calif.) Investigations Report 97-4205. spray pesticides in the San California Department of Water Hughes, R.M., and Gammon, J.R., Francisco Estuary, California: Resources, 1991, Management of 1987, Longitudinal changes in Environmental Toxicology and the California State Water fish assemblages and water Chemistry, v. 14, no. 7, Project: California Department of quality in the Willamette River, p. 1141–1150.

32 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 REFERENCES

MacCoy, D.E., Crepeau, K.L., and Mueller, D.K., and Helsel, D.R., 1996, Final report of the San Joaquin Kuivila, K.M., 1995, Dissolved Nutrients in the Nation’s Valley Drainage Program: waters—Too much of a good pesticide data for the San Joaquin [Sacramento, Calif.], San Joaquin River at Vernalis and the thing?: U.S. Geological Survey Valley Drainage Program, 183 p. at Sacramento, Circular 1136, 24 p. California, 1991–94: U.S. Mueller, D.K., Hamilton, P.A., Helsel, U.S. Bureau of Reclamation, 1990, Geological Survey Open-File D.R., Hitt, K.J., and Ruddy, B.C., Report of operations: U.S. Bureau Report 95-110, 27 p. 1995, Nutrients in ground water of Reclamation, Mid-Pacifric and surface water of the United Madison, R.J., and Brunett, J.O., 1985, Region, Central Valley States: An analysis of data Operations Coordinating Office, Overview of the occurrence of through 1992: U.S. Geological 42 p. nitrate in ground water in the Survey Water-Resources United States, in U.S. Geological Investigations Report 95-4031, U.S. Environmental Protection Survey, National Water Summary 74 p. Agency, 1986, Quality criteria for 1984—Hydrologic events, National Academy of Sciences and water 1986 (“Gold Book”): U.S. selected water-quality trends, and National Academy of Environmental Protection ground-water resources: U.S. Engineering, 1973 [1974], Water Agency, Office of Water Geological Survey Water-Supply quality criteria, 1972: U.S. Regulations and Standards, EPA Paper 2275, p. 93–105. Environmental Protection 440/5-85-001. Meador, M.R., Cuffney, T.F., and Agency, EPA R3-73-033, 594 p. Gurtz, M.E., 1993a, Methods for Panshin, S.Y., Dubrovsky, N.M., Zaugg, S.D., Sandstrom, M.W., Smith sampling fish communities as part Gronberg, J.M., and Domagalski, S.G., and Fehlberg, K.M., 1995, of the National Water-Quality J.L., in press, Occurrence and Methods of analysis by the U.S. Assessment Program: U.S. distribution of dissolved Geological Survey National Geological Survey Open-File pesticides in the lower San Water Quality Laboratory— Joaquin River Basin, California: Report 93-104, 40 p. Determination of pesticides in U.S. Geological Survey Water- water by C-18 solid-phase Meador, M.R., Hupp, C.R., Cuffney, Resources Investigations Report T.F., and Gurtz, M.E., 1993b, 98-4032. extraction and capillary-column Methods for assessing stream San Joaquin Valley Drainage Program, gas chromatography/mass habitat as part of the National 1990, A management plan for spectrometry with selected-ion Water-Quality Assessment agricultural subsurface drainage monitoring: U.S. Geological Program: U.S. Geological Survey and related problems on the Survey Open-File Report 95-181, Open-File Report 93-408, 48 p. westside San Joaquin Valley: 49 p.

U.S. Geological Survey Circular 1159 33 GLOSSARY

The terms in this glossary were compiled from numerous sources. Some definitions have been modified and may not be the only valid ones for these terms.

Algae—chlorophyll-bearing non- Base flow—Sustained, low flow in a Chlorofluorocarbons—A class of vascular, primarily aquatic species that stream; ground-water discharge is the volatile compounds consisting of have no true roots, stems, or leaves; source of base flow in most places. carbon, chlorine, and fluorine. most algae are microscopic, but some Commonly called freons, which have species can be as large as vascular Basic Fixed Sites—Sites on streams been used in refrigeration plants. at which streamflow is measured and mechanisms, as blowing agents in the samples are col-lected for temperature, fabrication of flexible and rigid foams, Alluvial aquifer—A water-bearing salinity, suspended sediment, major and, until several years ago, as deposit of unconsolidated material ions and metals, nutrients, and organic propellants in spray cans. (sand and gravel) left behind by a river or other flowing water. carbon to assess the broad-scale spatial and temporal character and Community—In ecology, the species that interact in a common area. Alluvium—Deposits of clay, silt, transport of inorganic constituents of sand, gravel or other particulate rock stream water in relation to hydrologic Concentration—The amount or mass material left by a river in a streambed, conditions and environmental settings. on a flood plain, delta, or at the base of a substance present in a given of a mountain. Basin—See . volume or mass of sample. Usually expressed as micrograms per liter Ammonia—A compound of nitro-gen Bed sediment—The material that (water sample) or micro- grams per kilogram (sediment or tissue sample). and hydrogen (NH3) that is a common temporarily is stationary in the bottom byproduct of animal waste. Ammonia of a stream or other watercourse. readily converts to nitrate in soils and Confluence—The flowing together of streams. Bed sediment and tissue two or more streams; the place where a tributary joins the main stream. studies—Assessment of concentra- Anomalies—As related to fish, tions and distributions of trace externally visible skin or subcu- Contamination—Degradation of elements and hydrophobic organic taneous disorders, including water quality compared to original or contaminants in streambed sedi-ment deformities, eroded fins, lesions, and natural conditions due to human and tissues of aquatic organ-isms to tumors. activity. identify potential sources and to assess Aquatic life criteria—Water-quality spatial distribution. Criterion—A standard rule or test on guidelines for protection of aquatic which a judgment or decision can be life. Often refers to U.S. Benthic invertebrates—Insects, based. Environmental Protection Agency mollusks, crustaceans, worms, and water-quality criteria for protec-tion of other organisms without a back-bone Cubic foot per second—(ft3/s, or cfs) aquatic organisms. See Water-quality that live in, on, or near the bottom of is the rate of water discharge guidelines, Water-quality criteria, and lakes, streams, or oceans. representing a volume of a 1 cubic Freshwater chronic criteria. foot passing a given point during 1 Biota—Living organisms. second, equivalent to approxi-mately Aquifer—A water-bearing layer of 7.48 gallons per second or 448.8 soil, sand, gravel, or rock that will Chlordane—Octachloro-4,7- yield usable quantities of water to a gallons per minute or 0.02832 cubic methanotetrahydroindane. An well. meter per second. organochlorine insecticide no longer Background concentration—A registered for use in the United States. Degradation products—Com-pounds concentration of a substance in a Technical chlordane is a mixture in resulting from trans-formation of an particular environment that is which the primary components are cis- organic substance through chemical, indicative of minimal influence by and trans-chlordane, cis- and trans- photochemical, and(or) biochemical human (anthropogenic) sources. nonachlor, and heptachlor. reactions.

34 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 GLOSSARY

Denitrification—A process by which protect the public welfare; guide-lines Fertilizer—Any of a large number of oxidized forms of nitrogen such as have no regulatory status and are natural or synthetic materials, - nitrate (NO3 ) are reduced to form issued in an advisory capacity. including manure and nitrogen, nitrites, nitrogen oxides, ammonia, or phosphorus, and potassium com- free nitrogen: com-monly brought Ecological studies—Studies of pounds, spread on or worked into soil about by the action of denitrifying biological communities and habitat to increase its fertility. bacteria and usually resulting in the characteristics to evaluate the effects escape of nitrogen to the air. of physical and chemical characteristics of water and hydro- Fish community—See Community. Detection limit—The concentra-tion logic conditions on aquatic biota and below which a particular analytical to determine how biological and Flow path—An underground route method cannot deter-mine, with a high habitat characteristics differ among for ground-water movement, degree of certainty, a concentration. environmental settings in NAWQA extending from a recharge (intake) Study Units. zone to a discharge (output) zone such DDT—dichloro-diphenyl-trichloro- Ecoregion—An area of similar as a shallow stream. ethane. An organochlorine insect-icide climate, landform, soil, potential no longer registered for use in the natural vegetation, hydrology, or other Freshwater chronic criteria—The United States. ecologically relevant variables. highest concentration of a contami- nant that freshwater aquatic organisms Dieldrin—An organochlorine Ecosystem—The interacting popu- can be exposed to for an extended insecticide no longer registered for use lations of plants, animals, and period of time (4 days) without in the United States. Also a microorganisms occupying an area, adverse effects. See Water-quality degradation product of the insecticide plus their physical environment. aldrin. criteria. Effluent—Outflow from a partic-ular Discharge—Rate of fluid flow source, such as a stream that flows Fumigant—A substance or mix-ture passing a given point at a given from a lake or liquid waste that flows of substances that produce gas, vapor, moment in time, expressed as volume from a factory or sewage-treatment fume, or smoke intended to destroy per unit of time. plant. insects, bacteria, or rodents. Dissolved solids—Amount of Environmental setting—Land area Ground water—In general, any water minerals, such as salt, that are characterized by a unique combi- that exists beneath the land surface, dissolved in water; amount of nation of natural and human-related dissolved solids is an indicator of factors, such as row-crop cultivation but more commonly applied to water salinity or hardness. or glacial-till soils. in fully saturated soils and geologic formations. Ephemeral stream—A stream or part Drainage basin—The portion of the of a stream that flows only in direct surface of the Earth that con-tributes Habitat—The part of the physical response to precipitation or snowmelt. water to a stream through overland environment where plants and animals Its channel is above the water table at runoff, including tributaries and all times. live. impoundments. Erosion—The process whereby Herbicide—A chemical or other Drinking-water standard or materials of the Earth's crust are agent applied for the purpose of guideline—A threshold concen- loosened, dissolved, or worn away and killing undesirable plants. See also tration in a public drinking-water simultaneously moved from one place Pesticide. supply, designed to protect human to another. health. As defined here, standards are U.S. Environmental Protection Eutrophication—The process by Hydrograph—Graph showing Agency regulations that specify the which water becomes enriched with variation of water elevation, velo-city, maximum contamination levels for plant nutrients, most com-monly streamflow, or other property of water public water systems required to phosphorus and nitrogen. with respect to time.

U.S. Geological Survey Circular 1159 35 GLOSSARY

Insecticide—A substance or mix-ture Mean—The average of a set of Nitrate—An ion consisting of - of substances intended to destroy or observations, unless otherwise nitrogen and oxygen (NO3 ). Nitrate is repel insects. specified. a plant nutrient and is very mobile in soils. Intensive Fixed Sites—Basic Fixed Mean discharge (MEAN)—The Sites with increased sampling fre- arithmetic mean of individual daily Nonpoint source—A pollution source quency during selected seasonal mean discharges during a specific that cannot be defined as originating periods and analysis of dissolved period, usually daily, monthly, or from discrete points such as pipe pesticides for 1 year. Most NAWQA annually. discharge. Areas of fertilizer and Study Units have one to two integrator pesticide applications, atmospheric Intensive Fixed Sites and one to four Median—The middle or central value indicator Intensive Fixed Sites. deposition, manure, and natural inputs in a distribution of data ranked in from plants and trees are types of order of magnitude. The median is Invertebrate—An animal having no nonpoint source pollution. also known as the 50th percentile. backbone or spinal column. See also Benthic invertebrates. Nutrient—Element or compound Metabolite—A substance pro-duced essential for animal and plant growth. in or by biological processes. Irrigation return flow—The part of Common nutrients in fertilizer include irrigation applied to the surface that is nitrogen, phos-phorus, and potassium. not consumed by evapotranspiration Method detection limit—The minimum concentration of a sub- or uptake by plants and that migrates Organochlorine compound— stance that can be accurately ident- to an aquifer or surface-water body. Synthetic organic compounds ified and measured with present containing chlorine. As generally Land-use study—A network of laboratory technologies. used, term refers to compounds existing shallow wells in an area having a relatively uniform land use. Micrograms per liter (µg/L)—A unit containing mostly or exclusively These studies are a subset of the expressing the concentration of carbon, hydrogen, and chlorine. Study-Unit Survey and have the goal constituents in solution as weight Examples include organo-chlorine of relating the quality of shallow (micrograms) of solute per unit insecticides, polychlor-inated ground water to land use. See Study- volume (liter) of water; equivalent to biphenyls, and some solvents Unit Survey. one part per billion in most containing chlorine. streamwater and ground water. One Organochlorine insecticide—A class Leaching—The removal of materials thousand micrograms per liter equals 1 of organic insecticides con-taining a in solution from soil or rock to ground mg/L. water; refers to movement of high percentage of chlorine. Includes dichlorodi-phenylethanes (such as pesticides or nutrients from land Milligrams per liter (mg/L)—A unit DDT), chlorinated cyclodienes (such surface to ground water. expressing the concentration of as chlordane), and chlorinated ben- chemical constituents in solu-tion as Load—General term that refers to a zenes (such as lindane). Most weight (milligrams) of solute per unit material or constituent in solu-tion, volume (liter) of water; equivalent to organochlorine insecticides were suspension, or in transport; usually one part per million in most banned because of their carcino- expressed in terms of mass or volume. streamwater and ground water. One genicity, tendency to bioaccu-mulate, and toxicity to wildlife. Main stem—The principal course of a thousand micrograms per liter equals 1 river or a stream. mg/L. Organophosphate insecticides—A Maximum contaminant level Monitoring well—A well designed class of insecticides derived from (MCL)—Maximum permissible level for measuring water levels and testing phosphoric acid. They tend to have of a contaminant in water that is ground-water quality. high acute toxicity to verte-brates. delivered to any user of a public water Although readily metab-olized by system. MCL's are enforceable Mouth—The place where a stream vertebrates, some metabolic products standards established by the U.S. discharges to a larger stream, a lake, are more toxic than the parent Environmental Protection Agency. or the sea. compound.

36 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 GLOSSARY

Pesticide—A chemical applied to Semivolatile organic compound Subsurface drain—A shallow drain crops, rights of way, lawns or (SVOC)—Operationally defined as a installed in an irrigated field to residences to control weeds, insects, group of synthetic organic com- intercept the rising ground-water level fungi, nematodes, rodents or other pounds that are solvent-extractable and maintain the water table at an acceptable depth below the land "pests." and can be determined by gas surface. chromatography/mass spectrometry. SVOCs include phenols, phthalates, Phosphorus—A nutrient essential for Surface water—An open body of growth that can play a key role in and polycyclic aromatic hydrocarbons water, such as a lake, river, or stream. stimulating aquatic growth in lakes (PAH). and streams. Suspended (as used in tables of Species—Populations of orga-nisms chemical analyses)—The amount Precipitation—Any or all forms of that may interbreed and pro-duce (concentration) of undissolved water particles that fall from the fertile offspring having simi-lar material in a water-sediment mix-ture. It is associated with the material atmosphere, such as rain, snow, hail, structure, habits, and functions. retained on a 0.45-micro-meter filter. and sleet. Specific conductance—A measure of Suspended sediment—Particles of the ability of a liquid to conduct an Radon—A naturally occurring, rock, sand, soil, and organic detritus electrical current. colorless, odorless, radioactive gas carried in suspension in the water formed by the disintegration of the column, in contrast to sediment that Streamflow—A type of channel flow, element radium; damaging to human moves on or near the streambed. applied to that part of sur-face runoff lungs when inhaled. in a stream whether or not it is Suspended-sediment affected by diversion or regulation. concentration—The velocity- Recharge—Water that infiltrates the weighted concentration of suspended ground and reaches the saturated zone. Stream reach—A continuous part of sediment in the sampled zone (from a stream between two specified points. the water surface to a point Relative abundance—The number of approximately 0.3 foot above the bed) organisms of a particular kind present Study Unit—A major hydrologic expressed as milligrams of dry in a sample relative to the total system of the United States in which sediment per liter of water-sediment number of organisms in the sample. NAWQA studies are focused. Study mixture (mg/L). Units are geograph-ically defined by a Synoptic sites—Sites sampled during Riparian—Areas adjacent to rivers combination of ground- and surface- and streams with a high density, a short-term investigation of specific water features and generally water-quality conditions during diversity, and productivity of plant encompass more than 4,000 square selected seasonal or hydro-logic and animal species relative to nearby miles of land area. conditions to provide improved spatial uplands. resolution for critical water-quality Study Unit Survey—Broad conditions. Runoff—Excess rainwater or snow- assessment of the water-quality melt that is transported to streams by conditions of the major aquifer Total DDT—The sum of DDT and its overland flow, tile drains, or ground systems of each Study Unit. The metabolites (breakdown products), water. Study-Unit Survey relies primarily on including DDD and DDE. sampling existing wells and, wherever Trace element—An element found in Sediment—Particles, derived from possible, on existing data collected by only minor amounts (concen-trations rocks or biological materials, that have other agencies and programs. less than 1.0 milligram per liter) in been transported by a fluid or other Typically, 20 to 30 wells are sampled water or sediment; includes arsenic, natural process, sus-pended or settled in each of three to five aquifer cadmium, chromium, copper, lead, in water. subunits. mercury, nickel, and zinc.

U.S. Geological Survey Circular 1159 37 GLOSSARY

Urban Site—A site that has greater Water-quality guidelines—Specific Water year—The continuous 12- than 50 percent urbanized and less levels of water quality which, if month period, October 1 through than 25 percent agricul- tural area. reached, may adversely affect human September 30, in U.S. Geological Survey reports dealing with the Volatile organic compounds health or aquatic life. These are surface-water supply. The water year (VOC)—Organic chemicals that have nonenforceable guide-lines issued by a is designated by the calendar year in a high vapor pressure relative to their governmental agency or other which it ends and which includes 9 of water solubility. VOCs include institution. the 12 months. Thus, the year ending components of gasoline, fuel oils, and September 30, 1980, is referred to as lubricants, as well as organic solvents, Water-quality standards—State- the "1980" water year. fumigants, some inert ingredients in adopted and U.S. Environmental pesticides, and some by-products of Protection Agency-approved ambi-ent Wetlands—Ecosystems whose soil is chlorine disinfection. standards for water bodies. Standards saturated for long periods seasonally include the use of the water body and or continuously, including marshes, Water-quality criteria—Specific the water-quality criteria that must be swamps, and ephemeral ponds. levels of water quality which, if reached, are expected to render a body met to protect the designated use or Withdrawal—The act or process of of water unsuitable for its designated uses. removing; such as removing water use. Commonly refers to water-quality from a stream for irrigation or public criteria estab-lished by the U.S. Watershed—See Drainage basin. water supply. Environmental Protection Agency. Water-quality criteria are based on Water table—The point below the specific levels of pollutants that would land surface where ground water is make the water harmful if used for first encountered and below which the drinking, swimming, farming, fish earth is saturated. Depth to the water produc-tion, or industrial processes. table varies widely across the country.

38 Water Quality in the San Joaquin–Tulare Basins, California, 1992–95 Dubrovsky and others • Water Quality in the San Joaquin-Tulare Basins USGS Circular 1159 • 1998

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