Updated 3/16/10 

Surface Water Monitoring Program 

for Pesticides in Salmonid-Bearing Streams 

Background 

Summary 2006 - 2008 Sampling Periods

Summary Report

2007 Sampling Period

Fact Sheet

Final Report

2006 Sampling Period

Fact Sheet 

Final Report 

Summary 2003 - 2005 Sampling Periods

Fact Sheet

Summary Report

2004 Sampling Period

Fact Sheet 

Final Report 

2003 Sampling Period

Fact Sheet 

Final Report 

Quality Assurance Project Plan 

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BACKGROUND 

WSDA and the Washington State Department of Ecology (Ecology) are conducting a multi-year monitoring study 

to evaluate pesticide concentrations in surface waters. The study was designed to address pesticide presence in 

Endangered Species Act (ESA)-listed, salmonid-bearing streams during typical pesticide use periods. Monitoring is 

conducted weekly in selected salmonid-bearing streams from March through October. 

The data collected will allow WSDA, EPA, and the National Atmospheric and Oceanic Administration (NOAA) - 

Fisheries to refine exposure assessments for pesticides registered for use in Washington state. Understanding the 

fate and transport of pesticides used in Washington state allows regulators to make appropriate decisions to 

protect ESA-listed species while minimizing the economic impacts to agriculture. 

Ecology's Environmental Assessment Program (EAP) conducts the sampling program and laboratory analyses. A 

wide range of pesticides including organochlorines, organophosphates, carbamates, as well as historical use 

pesticides and breakdown products, are included in this study. The samples are analyzed at or through Ecology's 

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Manchester Laboratory. 

EAP also enters the data into Ecology's Environmental Information Management database. 

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Summary: 2006-2008 Sampling Periods 

Surface Water Monitoring Program for Pesticides in Salmonid-Bearing Streams 2006-2008 Triennial 

Report

The summarized results for 2006-2008 are reported in Surface Water Monitoring 

Program for Pesticides in Salmonid-Bearing Streams 2006-2008 Triennial Report. 

Monitoring is being conducted in five basins: 

During the 2006-2008 monitoring period, the majority of detected pesticides met water quality standards or 

assessment criteria. 

Over the three years, 74 pesticides were detected. Of these, six insecticides did not meet a water quality 

standard or assessment criterion: permethrin, chlorpyrifos, diazinon, azinphos-methyl, malathion, and 

endosulfan. The other pesticide that did not meet a water quality standard was total DDT, which has not been 

registered for use in the United States since 1972. 

For all monitoring sites, co-occurrence of insecticides with a similar mode of action (acetylcholinesterase 

inhibitors) rarely occurred. 

The only significant trend found in pesticide levels was a decrease in the number of herbicide detections in 

Thornton Creek during 2006-2008 as compared to 2003-2005. 

None of the sites sampled in 2006-2008 met water quality standards for temperature. In addition, Thornton 

Creek and the Skagit-Samish agricultural drainages did not meet water quality standards for dissolved oxygen. 

High water temperatures and low dissolved oxygen levels are of concern for the fisheries resource in Indian 

Slough, Browns Slough, and Big Ditch in the Skagit-Samish basin. Temperature levels for the lower Yakima sites 

during some periods are of concern for steelhead fisheries. 

Pesticide concentrations found in this 2006-2008 study likely do not directly affect salmonids. Pesticide 

concentrations at some sites may affect aquatic invertebrate populations which serve as a prey base for 

salmonids. 

2007 Sampling Period 

FACT SHEET - July 2008 

WSDA has developed a fact sheet summarizing the sampling activities and results and 

includes a brief description of the future direction of the Surface Water Monitoring Program. 

The fact sheet may be downloaded and reproduced. 

For complete results from the surface water monitoring study, refer to the report, Surface

 Thornton Creek in the Cedar-Sammamish basin representing urban land use. 

 Lower Skagit-Samish basin representing western Washington agricutultural practices. 

 Lower Yakima basin representing irrigated agriculture. 

 Wenatchee and Entiat basins representing tree fruit agriculture. 

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Water Monitoring Program for Pesticides in Salmonid-Bearing Streams, 2007 Data Summary.

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FINAL REPORT - SURFACE WATER MONITORING PROGRAM FOR PESTICIDES IN 

SALMONID-BEARING STREAMS, 2007 DATA SUMMARY 

The results from the 2007 study are reported in Surface Water Monitoring Program 

for Pesticides in Salmonid-Bearing Streams, 2007 Data Summary. 

Five watersheds were monitored for the 2007 study because they support several 

salmonid populations, produce a variety of agricultural commodities, and have a high 

percentage of cultivated land area. The monitoring locations were 1) Thornton Creek â€” 

WRIA 8, 2) Lower Skagit-Samish â€” WRIA 3, 3) Lower Yakima â€” WRIA 37, 4) 

Wenatchee â€” WRIA 45, and 5) Entiat â€” WRIA 46. 

Year 2007 is the first in a three-year study cycle to investigate pesticides in the Wenatchee and Entiat 

watersheds, second in a three-year cycle in the Skagit-Samish watershed and the fifth in a six-year cycle in the 

Cedar-Sammamish and Lower Yakima watersheds. 

The study analyzed 152 registered and historical-use pesticides, including organochlorine, organophosphorous, 

and carbamate pesticides. Conventional water quality parameters â€“ total suspended solids, pH, conductivity, 

temperature, and flow â€“ were also measured to better understand factors influencing pesticide toxicity, fate 

and transport, and general water quality. 

During 2007, 64 currently registered pesticides, historical-use pesticides and degradates were detected. The 

majority of pesticide detections where close to analytical detection limits. Herbicides were the most commonly 

detected class of pesticides. However, regional differences in pest pressures are illustrated by the different 

percentages of pesticide classes detected in each basin. 

In the urban basin, dichlobenil (CasoronÂ®) was the most frequently detected pesticide. Tebuthiuron, atrazine 

and DDE (a degradate of DDT) were the most commonly detected compounds in the agricultural basins â€“ 

Skagit, Lower Yakima and Wenatchee/Entiat respectively. 

Azinphos-methyl, chlorpyrifos, diazinon, DDT, DDE and endosulfan exceeded either a state water quality standard 

or recommended water quality criteria at least once in 2007. 

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2006 Sampling Period 

FACT SHEET - July 2007 

WSDA has developed a fact sheet summarizing the sampling activities and results 

and includes a brief description of the future direction of the Surface Water 

Monitoring Program. The fact sheet may be downloaded and reproduced. 

For complete results from the surface water monitoring study, refer to the report, 

Surface Water Monitoring Program for Pesticides in Salmonid-Bearing 

Streams, 2006 Monitoring Data Summary. 

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FINAL REPORT - SURFACE WATER MONITORING PROGRAM FOR PESTICIDES IN 

SALMONID-BEARING STREAMS, 2006 MONITORING DATA SUMMARY 

The results from the 2006 study are reported in Surface Water Monitoring Program 

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for Pesticides in Salmonid-Bearing Streams, 2006 Monitoring Data Summary. 

In 2006, pesticide concentrations were measured in three watersheds representing urban and agricultural landuse patterns. The monitoring locations and watersheds that were chosen had a likely combination of off-site 

pesticide transport and use by salmonids. 

Thornton Creek in the Cedar-Sammamish watershed was selected as the urban watershed. The Lower SkagitSamish Watershed and the Lower Yakima watershed were selected to represent western and eastern agricultural 

land-use practices, respectively. 

Laboratory analyses were conducted for 165 pesticide, herbicide, and degradate compounds. These compounds 

were selected based on the use of the pesticide, toxicity to non-target organisms, transport potential, and cost of 

analysis. Conventional water quality parameters - total suspended solids, pH, conductivity, temperature, and flow 

- were measured to better understand factors influencing pesticide toxicity, fate and transport, and general water 

quality. 

Concentrations of all pesticide detected were generally low and close to analytical detection limits. When 

pesticides were detected, the most commonly found general pesticide category for both the urban and 

agricultural basins was herbicides. Dichlobenil (Casoron) was the most frequently detected compound in the 

urban watershed. Atrazine was the most frequently detected compound in the eastern agricultural basins while 

2,4-D was the most frequently detected compound in the western basins. 

Azinphos-methyl, chlorpyrifos, and DDE exceeded either a state water quality standard or a recommended water 

quality criteria at least once during 2006. 

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Summary: 2003 - 2005 Sampling Periods 

FACT SHEET 2003-2005 

WSDA has developed a fact sheet summarizing the first three years (2003 - 2005) of 

the Surface Water Monitoring Program. This summary contains a synopsis of the 

sampling activities and results, and discussion of the findings. The fact sheet may be 

downloaded and reproduced. 

For detailed information about the first three years of the surface water monitoring 

study, refer to the report Surface Water Monitoring Program for Pesticides in Salmonid-Bearing Streams, 

2003 - 2005. 

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SUMMARY REPORT - SURFACE WATER MONITORING PROGRAM FOR PESTICIDES IN 

SALMONID-BEARING STREAMS, 2003 - 2005 

The summarized results for the first three years (2003 - 2005) of the study are reported 

in Surface Water Monitoring Program for Pesticides in Salmonid-Bearing Streams, 

2003 - 2005. 

From 2003 to 2005, approximately 160 currently registered and historical-use pesticides, 

as well as degradates were included in the study. These compounds were selected based 

on the use of the pesticide, toxicity to non-target organisms, transport potential, and 

cost of analysis. Conventional water quality parameters - total suspended solids, pH, 

conductivity, temperature, and flow - were also measured to better understand factors influencing pesticide 

toxicity, fate and transport, and general water quality. 

During this 3-year period, a total of 453 samples were collected from an urban and agricultural watershed. A 

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total of 51 currently registered pesticides, historical-use pesticides, and/or degradates were detected in the urban 

and agricultural watersheds. The majority of the pesticide detections were low and close to analytical detection 

limits. 

Ten of the 51 pesticides detected exceeded either water quality criteria or risk quotients for acute or chronic 

toxicity to fish or for aquatic invertebrates. These 10 pesticides are 4,4-DDE, 4,4-DDT, azinphos-methyl, carbaryl, 

chlorpyrifos, diazinon, disulfoton, endosulfan sulfate, malathion, and oxyfluorfen. 

The azinphos-methyl and malathion detections occured at the same time summer maximum temperatures may 

restrict summer steelhead (ESA-listed) occupation of monitored stream reaches. If summer steelhead are 

present, elevated water temperatures outside of their optimal range may make the steelhead more susceptible to 

pesticide toxicity. 

The assessment criteria used for the 3-year report are based on assessing the effects of a specific chemical on an 

organism and do not take into account the additive or possibly synergistic effects of mixtures or sub-lethal 

effects. 

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2004 Sampling Period 

FACT SHEET - September 2005 

WSDA has developed a fact sheet summarizing the sampling activities and results 

and includes a brief description of the future direction of the Surface Water 

Monitoring Program. The fact sheet may be downloaded and reproduced. 

For complete results from the surface water monitoring study, refer to the report, 

Surface Water Monitoring Program for Pesticides in Salmonid-Bearing 

Streams, April through October 2004. 

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FINAL REPORT - SURFACE WATER MONITORING PROGRAM FOR PESTICIDES IN 

SALMONID-BEARING STREAMS APRIL TO OCTOBER, 2004 

The results from the second year (2004) of the study are reported in, Surface Water

Monitoring Program for Pesticides in Salmonid-Bearing Streams, April through 

October 2004. 

Two index watersheds, representing urban and agricultural land-use patterns, were 

sampled from March through October 2004. Thornton Creek in the Cedar-Sammamish 

watershed was chosen as the urban drainage. Marion Drain, Spring Creek, and Sulphur 

Creek Wasteway in the Lower Yakima watershed represented agricultural land-use 

patterns. Unfiltered water samples were collected weekly at downstream sites and every other week at upstream 

sites. 

Conventional parameters including discharge, temperature, pH, conductivity, and total suspended solid (TSS) 

were collected to characterize water quality of the streams and to investigate pesticide fate and toxicity. 

Concentrations of all pesticide detected were generally low and close to analytical detection limits. In the 

agricultural basin, 2,4-dichlorophenylacetic acid (2,4-D) was the most commonly detected pesticide; however, 

dichlobenil was most commonly detected in the urban watershed. 

Pesticide detections were compared to Washington State promulgated and EPA recommended aquatic life 

criteria. Detections were also compared to EPA, Office of Pesticide Programs, Environmental Fate and Effects 

Division acute and chronic toxicological endpoints used for pesticide registration. 

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Five pesticides - azinphos-methyl, chlorpyrifos, diazinon, malathion, and 4,4'-DDE - were above the numeric 

component of various standards, but the weekly sampling frequency of this study does not allow for assessment 

of the temporal component of these standards. A single detection of malathion (3.05 g/L) approached the acute 

LC50 for rainbow trout (4 g/L) in the Marion Drain. 

 

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2003 Sampling Period 

FACT SHEET - November 2004 

WSDA has developed a fact sheet summarizing the sampling activities and results 

and includes a brief description of the future direction of the Surface Water 

Monitoring Program. The fact sheet may be downloaded and reproduced. 

For complete results from the surface water monitoring study, refer to the report, 

Surface Water Monitoring Program for Pesticides in Salmonid-Bearing Streams 

April to December, 2003. 

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FINAL REPORT - SURFACE WATER MONITORING PROGRAM FOR PESTICIDES IN 

SALMONID-BEARING STREAMS APRIL TO DECEMBER, 2003 

The results from the Year One of the monitoring effort (April through December 2003) 

are presented in the report, Surface Water Monitoring Program for Pesticides in 

Salmonid-Bearing Streams, April to December, 2003. 

 

Overall, the sampling results were positive. Both the agricultural and urban sampling 

resulted in approximately 96 percent non-detections with the remaining 4 percent split 

between validated numerical results and estimated detected values. Refer to the report 

for a complete discussion of the sampling results. 

Year One of the study assessed the occurrence of pesticides in surface water in two index watersheds that 

represented agricultural and urban land-use patterns. 

Three drainages in the Lower Yakima Watershed Resource Inventory Area 37 (WRIA 37) were selected to 

represent agricultural land use patterns: Spring Creek, Sulphur Creek Wasteway, and Marion Drain. These subbasins were selected because they have the highest percent area cropped and a diversity of agriculture within 

the drainage. 

Thornton Creek, located in the Cedar-Sammamish Water Resource Inventory Area 8 (WRIA 8), was selected as 

the urban watershed due to prior salmon habitat enhancement efforts and the occurrence of pre-spawning 

mortality in Coho salmon. 

In both the agricultural and urban watersheds, ambient surface waters were sampled for 87 registered 

pesticides. The surface waters were also sampled for degradates and some historically used compounds such as 

DDT. In addition to pesticides, sampling for semi-volatile organic compounds (SVOC) was included in the urban 

basin. 

Fieldwork for Year One began the second week of April 2003. Sampling occurred weekly at all sites throughout 

the spring (April through June 2003). In the agricultural watershed, bi-weekly sampling at the mouths of the 

three sub-drainages continued through the summer. Semi-volatile organic compounds were measured in 

Thornton Creek bi-weekly April through June and also during three storm events in the fall of 2003. 

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QUALITY ASSURANCE PROJECT PLAN 

To assure the data for the project accurately and precisely represented conditions existing at the time of sample 

collection, WSDA and the Ecology Environmental Assessment Program developed a Quality Assurance Project 

Plan (QAPP). The objective of the QAPP is to provide valid data of known and documented quality for 

identifying pesticides that do and do not pose a risk to salmonids. 

WWSDA and Ecology have amended the QAPP to add the Entiat and Wenatchee watersheds (WRIAs 45 & 46 

in the Upper Columbia Basin) and the Lower Skagit-Samish watershed (WRIA 3) to the monitoring program. 

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If you have additional questions regarding the Surface Water Monitoring Program, please contact Jim Cowles at 

(360) 902-2066 or by e-mail at jcowles@agr.wa.gov. 

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