Dissolved Pesticides in the Alamo River and the , , 1996–97

Open-File Report 02-232

Prepared in cooperation with the CALIFORNIA STATE WATER RESOURCES CONTROL BOARD

U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY

Dissolved Pesticides in the Alamo River and the Salton Sea, California, 1996–97

By Kathryn L. Crepeau, Kathryn M. Kuivila, and Brian Bergamaschi

Prepared in cooperation with the

CALIFORNIA STATE WATER RESOUCRES CONTROL BOARD

Sacramento, California 2002

U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY Charles G. Groat, Director

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.

For additional information write to: Copies of this report can be purchased from:

U.S. Geological Survey U.S. Geological Survey Placer Hall, Suite 2012 Information Services 6000 J Street Building 810 Sacramento, CA 95819-6129 Box 25286, Federal Center http://ca.water.usgs.gov Denver, CO 80225-0286

CONTENTS

Abstract ...... 1 Introduction ...... 1 Sample Collection, Processing, and Analysis ...... 3 Sampling Results...... 4 Quality Assurance ...... 4 References Cited ...... 7

Contents iii

FIGURES

Figure 1. Map showing Alamo River and Salton Sea, California, showing pesticide sampling sites...... 2

Figures iv

TABLES

Table 1. Method detection linits, mean recovery, and relative standard deviation from seven determinations of pesticides spiked at a concentration of 50 nanograms per liter ...... 3 Table 2 Pesticide concentrations in water samples from the Alamo River and Salton Sea, California, August 1996 through April 1997...... 5

Tables v

Dissolved Pesticides in the Alamo River and the Salton Sea, California, 1996-97

By Kathryn L. Crepeau, Kathryn M. Kuivila, and Brian Bergamaschi

ABSTRACT percent irrigation runoff, which is discharged into the southeast end of the Salton Sea (fig. 1). Insecticide and Water samples were collected from the Alamo herbicide concentrations in the Alamo River and Salton River and the Salton Sea, California, in autumn 1996 Sea are high enough to be toxic to aquatic life during and late winter/early spring 1997 and analyzed for autumn and late winter/early spring when these dissolved pesticides. The two seasons chosen for compounds are applied (de Vlaming and others, 1998; sampling were during pesticide application periods in de Vlaming and others, 2000). DeVlaming and others the . Pesticide concentrations were showed that for a species of water flea, Ceriodaphia measured in filtered water samples using solid-phase dubia, the toxicity was caused primarily by extraction and analyzed by gas chromatography/mass chlorpyrifos and diazinon during three months in the spectrometry. Generally, the highest concentrations autumn, and primarily by carbofuran and diazinon were measured in the Alamo River. The concentrations during two months in the spring. of carbaryl, chlorpyrifos, cycloate, dacthal, diazinon, This report presents the results of pesticide and eptam were highest in samples collected in autumn sampling of the Alamo River and Salton Sea from late 1996. In contrast, the concentrations of atrazine, August to November1996 and late February to mid carbofuran, and malathion were highest in samples April 1997. Surface-water samples were analyzed for collected in late winter/early spring 1997. The highest 11 pesticides from seven sites. The first site, in the concentrations measured of atrazine, carbofuran, Alamo River, was chosen as representative of dacthal, eptam, and malathion all exceeded 1,000 agricultural runoff from the Imperial Valley. The six nanograms per liter. Salton Sea sites were chosen to assess the change in pesticide concentration as Alamo River water became mixed and interacted with Salton Sea water. The INTRODUCTION sampling was done to determine the pesticides and concentrations present in the Alamo River and Salton The Salton Sea in Imperial County, California, Sea during periods when deVlaming and others has been designated as a sensitive ecosystem by the showed the waters to be toxic to aquatic life. Federal and State governments because it contains The authors thank Lucian Baker II of the U.S. productive fisheries and provides important habitat for Geological Survey, and Kristy Cortright, Linda migratory birds. However, more than 6 million pounds Deanovic, Melenee Emanuel, and Karen Larsen of the (3 million kilograms) of pesticide-active ingredients Aquatic Toxicology Laboratory at University of are applied annually to vegetable crops grown year- California, Davis, for processing the samples; and Ray round in the Imperial Valley (California Department of Lukens of the California Regional Water Quality Pesticide Regulation, 1994). The Alamo River drains Control Board, River Basin Region, for the Imperial Valley, and its flow consists of almost 100 collecting the water samples.

Introduction 1

116°45'

EXPLANATION South Basin 33°15' Pesticide sampling site with number Salton Sea Mullet 1 Island Garst Road at Alamo River 5 6 4 Imperial Wildlife 2-7 National In Salton Sea at mouth of Alamo River 7 1 Management Area 2 (Wister Unit) Wildlife 3 Alamo Salton See Naval Test Base

Refuge SSNWR Unit 2 River

C

a l Imperial i f o r n Valley i a New River

MAP AREA SSNWR Unit 1

05 MILES

0 5 KILOMETERS

116°00' 45' 115°30'

Imperial Wildlife SALTON SEA Management Area (Wister Unit) South Basin 33°15' Salton Sea Mullet Salton Sea Island Niland Area of Naval National enlargement Test Base Alamo Wildlife

Refuge River

Calipatria

Creek San Felipe Wash San Felipe Trifolium New River

0 10 MILES Extension Trifolium Drain 0 10 KILOMETERS Westmorland

Figure 1. Map showing Alamo River and Salton Sea, California, showing pesticide sampling sites.

2 Dissolved Pesticides in the Alamo River and the Salton Sea, California, 1996–97

SAMPLE COLLECTION, PROCESSING, AND 0.7-micron glass-fiber filter and extracted using a C-8 ANALYSIS solid-phase extraction cartridge. The cartridges were then packed on ice and delivered to the USGS Water samples were collected from one site on California District Organic Chemistry Laboratory in the Alamo River and six near-shore sites in the Salton Sacramento, California, for analysis. Sea southeast of the Salton Sea National Wildlife The percent recovery and method detection Refuge (fig. 1). The samples were collected every few limits (MDL) of the pesticides were determined using weeks from August through November and from surface water from Suisun Bay, which has a similar February through April to coincide with the pesticide specific conductivity as that of the study sites; the application periods in the Imperial Valley (autumn and conductivity affects the extraction efficiency of the late winter/early spring). The samples were not solid-phase cartridge. The pesticides were analyzed by collected through integrated sampling methods as gas chromatography/mass spectrometry (GC/MS). The normally required by USGS methodology, but the river mean recoveries for the pesticides were between 78 is well mixed and the analyses are limited to dissolved and 114 percent and relative standard deviations were constituents and, therefore, are considered reliable below 10 percent; the detection limits were between 3 indicators of the water quality of the Alamo River. and 15 ng/L (nanograms per liter)(table 1). However, Subsurface grab samples were taken from the Alamo the pesticide recoveries and detection limits for Salton River at the Garst Road bridge, and using a boat in the Sea samples may be different than those given here; Salton Sea. although the specific conductivities of Salton Sea The water samples were shipped on ice to the samples were similar to Suisun Bay, the water matrix Aquatic Toxicology Laboratory at the University of was different. Additional details of the method are California at Davis, where they were filtered through a described by Crepeau and others (2000).

Table 1. Method detection linits, mean recovery, and relative standard deviation from seven determinations of pesticides spiked at a concentration of 50 nanograms per liter

[ng/L, nanograms per liter]

Relative Method Mean standard Pesticide detection recovery deviation limit (ng/L) (percent) (percent)

Atrazine 5 78 3 Carbaryl 10 90 6 Carbofuran 8 92 5 Chlorpyrifos 8 96 4 Cycloate 11 85 3 Dacthal 3 85 2 Diazinon 3 87 1 Eptam 5 88 3 Fonofos 5 96 3 Malathion 15 114 7 Simazine 5 84 3

Sample Collection, Processing, and Analysis 3

SAMPLING RESULTS Equipment blanks were organic-free water filtered into a 1-liter glass bottle then extracted and Insecticide and herbicide data from 52 water analyzed in the same way as the samples. A total of six samples collected from the Alamo River and Salton Sea blanks were analyzed on the GC/MS. Cycloate was are presented in table 2. For most compounds the detected in only one blank, at 3 ng/L, which indicates highest concentrations were detected in the Alamo that there was no systematic contamination from River and lower concentrations in the Salton Sea. The processing and analyzing the samples. concentrations of carbaryl, chlorpyrifos, cycloate, Replicate samples were collected to assess dacthal, diazinon, and eptam were highest in the variability, including matching both the nondetections samples collected in the autumn, ranging from 5 to 10 and numerical values of pesticides detected. Seven times the concentrations measured in the late pairs of replicates were analyzed at the USGS winter/early spring. In contrast, the concentrations of California District Organic Chemistry Laboratory. For atrazine, carbofuran, and malathion were highest in the 88 percent of the analyses, the nondetections were samples collected in the late winter/early spring, paired. Two pesticides were detected in the ranging from 5 to 200 times the concentrations environmental sample but not in the replicate. If the measured in the autumn. The highest concentrations of pesticide is detected in both the sample and the atrazine, carbofuran, dacthal, eptam, and malathion all replicate, the difference in the measured concentration exceeded 1,000 ng/L. The total pesticide concentration gives an assessment of the variability. The percent for all the samples ranged from 166 ng/L to 16,100 difference is defined as the absolute value of the ng/L. difference in the concentration between replicates Some of the pesticide concentrations are divided by their mean and then multiplied by 100. The reported as estimates because the concentrations mean percent difference is 3 percent (n=53). exceed 1,000 ng/L, the highest calibration standard. To further assess variability, 13 pairs of These estimates are based on a linear extension of the replicates were analyzed at two different laboratories. calibration curve and may underestimate actual One of the replicates was analyzed by the USGS pesticide concentrations owing to saturation of the ion National Water Quality Laboratory (NWQL) in trap detector at high concentrations (Eichelberger and Denver, Colorado, and the other by the USGS Budde, 1987). All estimated concentrations are California District Organic Chemistry Laboratory. The designated with an “E” in table 2. The lowest mean percent difference when the pesticides were calibration standard was 1 ng/L. Pesticide detected in both replicates is 13 percent (n=104). This concentrations that were present but below the method is a reasonable difference for pesticides analyzed at two detection limit are reported in parentheses. different laboratories and indicates the concentrations The data in table 2 are rounded using a model of the pesticides in the environmental samples and the that plots the standard deviation versus the replicates are within a factor of 1.14 of each other. concentration to determine the number of significant Terbuthylazine was added as a surrogate to all figures for each compound. This method of rounding is samples, including equipment blanks, to quantify the based on the Phoenix Project for National Water extraction efficiency of the solid-phase cartridge and Quality Laboratory data and the American Society for GC/MS analysis. The average percent recovery for Testing Materials E29-93a (Phoenix Project, 2002; terbuthylazine was 85 percent and the standard American Society for Testing and Materials, 1993). deviation was 15 percent. Sample data were excluded from this report if the recovery of terbuthylazine was +/- 1.5 standard deviations from the mean recovery for QUALITY ASSURANCE all samples. A total of four samples were excluded.

Quality assurance samples analyzed to determine contamination and variability included equipment blanks and replicates. Matrix spikes were not included in this study.

4 Dissolved Pesticides in the Alamo River and the Salton Sea, California, 1996–97

5.0 6.8 nd nd nd nd nd nd nd 15.9 11.0 nd 16.8 nd nd nd nd nd nd nd nd nd 18.5 nd (1) (2) (ng/L) Simazine nd nd 35 98 nd 13.8 35 65 37 59 nd nd 90 (9) (2) 169 114 178 750 195 134 173 261 119 179 (ng/L) E1,340 Malathion 5.6 7.7 9.9 nd nd 30.7 16.5 25.2 19.6 14.8 nd 80 27.5 23.3 nd nd nd 77 27.8 24.0 nd nd nd 54.4 (2) (ng/L) 101 Fonofos ater samples were collected and pH, W 44.6 38.8 42.4 98 42.0 252 252 127 525 104 401 326 ptam (ng/L) E1,560 E9,100 E6,410 E1,190 E2,030 E1,090 E3,350 E1,310 E E13,000 E12,300 E10,000 E12,400 E13,800 E10,600 Estimate of pesticide concentration; determined , 8.4 5.5 5.6 9.7 10.4 36.7 29.1 16.6 34.0 48.6 11.1 32.8 29.1 nued 553 355 417 165.2 144.0 109.9 414 411 156.8 468 437 155.2 285 (ng/L) Diazinon 10.0 46.6 nd 44.4 25.2 nd 24.9 10.6 334 151 974 912 961 507 1,000 (ng/L) Dacthal E1,290 E1,350 E1,040 E1,030 E1,330 E1,160 E1,030 E1,020 E1,200 E1,010 E1,020 w the detection limit; E 91 30.5 13.6 81 nd 84 nd (3) (7) (3) (6) (3) (2) (3) ut belo (ng/L) 153 601 193 111 130 416 115 127 501 105 112 306 Cycloate 36.1 34.3 76 57 18.9 26.3 10.8 37.8 35.0 93 77 13.9 42.5 34.7 96 71 35.0 31.3 73 (4) (3) (ng/L) 107 152 102 110 111 Chlor- pyrifos nd 11.2 nd 35.5 83 58 nd nd nd nd 32.5 58 nd nd nd 26.6 33.2 nd nd nd 740 870 133 179 ran (ng/L) Carbofu E3,010 E2,450 nd nd 78 53 27.5 nd nd 79 28.3 nd nd nd 82 nd nd nd 60 (8) (6) 160 135 230 120 322 111 360 (ng/L) Carbaryl alue is probably an underestimate of the pesticide concentration; --, not recorded. ater Quality Control Board] 86 54.8 32.0 42.3 48.4 38.1 31.0 81 58.8 37.8 61.8 39.3 82 55.9 39.7 64.7 56.8 82 70 59.8 W 840 358 315 213 224 (ng/L) E3,180 Atrazine gional (ºC) ature 31 30 26 19 25 18 16.5 18.4 17 22 31 30 28 25 19 20.5 22 31 30 28 25 21 21 31 30 28 emper- 1 1 1 T 3,440 4,000 3,000 3,400 3,380 3,400 3,600 2,500 2,400 3,200 3,700 5,000 5,000 3,600 3,600 6,000 5,000 5,000 4,000 8,000 tance 1 17,000 10,300 15,000 10,500 17,000 33,000 (uS/cm) conduc- Specific 1 1 pH 7.8 7.6 8.0 7.8 8.1 7.7 8.0 7.9 7.6 7.3 7.8 7.6 8.0 8.1 7.7 7.3 7.6 7.9 7.6 7.9 8.1 8.2 7.2 7.8 7.7 8.0 1 1 1 1 1 1 1 ime T 1125 1200 1640 1500 -- 1030 1230 -- 1200 1630 1015 1000 1540 -- 1200 1515 -- 1049 1100 1500 -- 1310 1400 1005 1115 1510 Date Pesticide concentrations in water samples from the Alamo River and Salton Sea, California, August 1996 through April 1997—Conti Pesticide concentrations in water samples from the Alamo River and Salton Sea, California, August 1996 through April 1997 08/28/96 09/10/96 10/01/96 10/21/96 10/31/96 11/12/96 11/18/96 02/27/97 03/05/97 03/25/97 08/28/96 09/10/96 10/01/96 10/31/96 11/12/96 03/25/97 04/15/97 08/28/96 09/10/96 10/01/96 10/31/96 11/12/96 04/15/97 08/28/96 09/10/96 10/01/96 c conductance, and temperature were measured by California Re 1 2 3 4 fi site S/cm, microSiemens per centimeter at 25º Celsius; ng/L, nanograms liter; nd, not detected; ( ), pesticide is present b Sampling alue is greater than highest standard calibration of1,000 ng/L and therefore, this v Table 2. Table 2 [µ v speci

Quality Assurance 5 7.7 6.3 6.6 6.2 38.5 48.6 nd nd nd 47.9 57.7 19.4 nd 32.4 nd 48.1 94 18.2 41.8 31.5 nd nd 51.3 15.8 (4) (4) (ng/L) Simazine 21.6 62 nd nd nd 89 nd 32 38 nd nd 17.8 44 nd nd 60 14.9 17.2 150 174 117 110 990 197 110 910 (ng/L) Malathion 6.6 8.9 5.9 22.9 nd nd nd nd nd nd nd nd nd nd nd 39.7 nd nd nd nd nd 34.8 nd nd (1) (3) (ng/L) Fonofos 96 24.4 72 27.9 90 30.6 72 202 192 277 403 125 317 720 128 ptam (ng/L) E6,590 E1,080 E7,400 E2,650 E2,030 E8,000 E6,450 E1,380 E3,250 E5,060 E E13,100 5.3 9.5 4.2 4.7 9.7 4.4 94.8 44.8 20.2 73.6 51.0 32.0 10.6 30.1 96.1 20.3 28.2 83.6 19.6 nued 354 264 249 296 109.8 169.2 271 (ng/L) Diazinon 5.5 3.8 7.1 41.2 23.6 13.1 17.9 46.0 18.7 17.2 861 573 580 127 639 253 523 669 579 109 908 299 661 480 109 (ng/L) Dacthal E1,030 79 77 nd 73 89 61.1 44.1 nd nd 66.2 76 nd 62.0 66.1 nd (3) (4) (4) (8) (3) (4) (9) (ng/L) 111 238 106 185 Cycloate - 80 50 14.8 31.6 20.0 20.8 60 28.8 32.3 32.9 50 61 47.0 19.9 15.6 34.7 26.9 43.0 65 41.8 20.4 (3) (6) (2) (3) (1) (ng/L) Chlor pyrifos 63 nd 26.9 nd nd 30.4 nd nd nd nd 29.7 nd nd nd nd 60 nd 500 195 189 133 810 124 106 ran (ng/L) Carbofu E1,760 E1,540 51 nd nd nd nd nd nd nd nd nd nd 48 29.4 nd nd nd 42 nd (5) (5) (6) (4) 271 194 249 227 (ng/L) Carbaryl 82 96 83 68 74 92 93 61.8 75 95 97 94 68 71 86 281 259 110 158 193 665 372 206 103 611 192 (ng/L) Atrazine - (ºC) ature 25 18 21 21.5 32 31 29 25 21 21.5 23.5 31 30 30 25 20 16 21 23 33 31 29 25 20 17 23 emper 1 1 1 1 T c 5,000 tance 20,000 20,000 12,000 11,000 30,000 35,000 50,000 31,000 30,000 40,000 23,000 25,000 17,000 40,000 26,300 25,000 22,000 19,000 23,900 20,000 42,000 29,800 25,000 22,000 22,000 (uS/cm) conduc- Specifi 1 1 1 1 pH 8.1 8.1 7.5 8.1 8.1 7.8 8.1 8.1 7.9 7.9 8.2 8.0 7.8 8.1 8.0 8.3 7.8 8.0 8.2 8.1 7.6 8.0 8.0 8.3 8.3 8.3 1 1 1 1 1 1 1 1 ime T -- 1300 1500 -- 1034 1030 1520 -- 1220 1445 -- 1024 1020 1530 -- 1230 1045 1400 -- 1041 1130 1430 -- 1250 1115 -- alue. Date Pesticide concentrations in water samples from the Alamo River and Salton Sea, California, August 1996 through April 1997—Conti 10/31/96 11/12/96 03/25/97 04/15/97 08/28/96 09/10/96 10/01/96 10/31/96 11/12/96 03/25/97 04/15/97 08/28/96 09/10/96 10/01/96 10/31/96 11/12/96 03/05/97 03/25/97 04/15/97 08/28/96 09/10/96 10/01/96 10/31/96 11/12/96 03/05/97 04/15/97 Laboratory v 1 4 5 6 7 site Sampling Table 2.

6 Dissolved Pesticides in the Alamo River and the Salton Sea, California, 1996–97 REFERENCES CITED de Vlaming, V., Connor, V., DiGiorgio, C., Bailey, H., Deanovic, L., and Hinton, D., 2000, Application of American Society for Testing and Materials, 1993, Standard whole effluent toxicity test procedures to ambient water practice for using significant digits in test data to quality assessment: Environmental Toxicology and determine conformance to specifications: Annual book Chemistry, v. 19, no. 1, p. 42-62. of ASTM standards, Committee E-11 on Quality and de Vlaming, V., DiGiorgio, C., and Deanovic, L., 1998, Statistics, Subcommittee E11.10 on Sampling and Data Insecticide-caused toxicity in the Alamo River: Poster Analysis, ASTM E29-93a, p. 18-21. Presentation NorCal Society of Environmental California Department of Pesticide Regulation, 1994, Toxicology and Chemistry meeting, June 1998. Pesticide use data for 1993 (digital data): California Eichelberger, J.W., and Budde, W.L., 1987, Studies in mass Department of Pesticide Regulation, Sacramento, spectrometry with the ion trap detector: Biomedical and California. Environmental Mass Spectrometry, v. 14, p. 357-362. Crepeau, K.L., Baker, L.M., and Kuivila, K.M., 2000, Phoenix Project, 2002, Rounding requirements: Methods of analysis and quality-assurance practices for http://ok.water.usgs.gov/nawqa/phoenix/www/ determination of pesticides in water by solid-phase rounding.html; accessed January 9, 2002. extraction and capillary-column gas chromatography/mass spectrometry at the U.S. Geological Survey California District Organic Chemistry Laboratory, 1996-99: U.S. Geological Survey Open-File Report 00-229, 19 p.

References Cited 7