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 Manchester Laboratory.
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.
In 2006, pesticide concentrations were measured in three
watersheds representing urban and agricultural land-use
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 Skagit-Samish 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.
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.
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 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.
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,
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.
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 µg/L) approached the acute LC50 for rainbow trout
(4 µg/L) in the Marion Drain.
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.
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 sub-basins 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.
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.
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.
