California Environmental Protection Agency
Department of Pesticide Regulation
1020 N Street, Room 161
Sacramento, CA 95814
STUDY 154: PROTOCOL FOR MONITORING ACUTE AND CHRONIC TOXICITY IN THE SACRAMENTO RIVER WATERSHED: WINTER 1996-97
December 9, 1996
The Sacramento River is the largest river in California both in flow
and in drainage area (Figure 1). From Mount Shasta in the north to the
Sacramento-San Joaquin Delta in the south the river flows for 327 miles.
The river drains approximately 24,000 square miles including agricultural,
urban and undeveloped (Friebel et al., 1995). The Sacramento River provides
35% of the State's water supply, both drinking and agricultural, and is
also an important resource for recreation and wildlife (Reynolds, et al.,
1993). The primary source of water entering the system is surface runoff
from the Sierra Nevada Mountains to the east. Runoff from rain events occurring
in the Sacramento Valley provides significant short term increases in river
flow. Seasonal rains occur from October to March with little significant
rain from June to September. River flow during the summer is composed of
dam releases of snow melt water for agricultural, recreational and wildlife
In the Sacramento Valley, the organophosphorus insecticides diazinon
or methidathion are applied with a dormant oil on nut and stone fruit trees
to control peach twig borer, San Jose scale, European red mite and brown
mite pests. The best time to achieve control of these pests is December
through February, when the trees are dormant and better pesticide coverage
is possible (Zalom et al., 1995). This dormant orchard spray application
period, however, coincides with seasonal rainfall providing the potential
for these pesticides to wash off target areas and migrate with runoff waters
to the Sacramento River.
A one year Department of Pesticide Regulation (DPR) study and a three
year U.S. Geological Survey (USGS) study of the Sacramento River have shown
that most diazinon and methidathion concentrations were observed during
the dormant spray season (MacCoy et. al. 1995; Nordmark, 1995). Analysis
of rainfall data indicate that these higher concentrations occur almost
exclusively in conjunction with rain events. The DPR study, using weekly
three day composite samples, detected diazinon during January and February
1994 (Nordmark, 1995). No other organophosphate (OP) or carbamate (CB)
insecticides were detected. The USGS study, using grab samples collected
three times per week, detected diazinon each year from mid-January until
late February or early March. Analysis of the pesticide use reports (DPR
1991-1994) indicate the majority of dormant spray insecticides are applied
along the Sacramento River in northern Glenn and Butte Counties and along
the Feather River north of the Bear River. The OP insecticides diazinon
and methidathion are applied in nearly identical areas (Figures 2 and 3).
Runoff from dormant orchards west of the Sacramento River may flow into
the Colusa Basin Drain which enters the Sacramento River at Knights Landing.
Runoff from dormant spray areas east of the Sacramento River principally
drain into Butte Creek whose flow has been engineered to enter the Sacramento
River at Karnak via the Sutter Bypass. Over half of the dormant spray applications
of diazinon and methidathion occur along the Feather River (Figure 2 and
3). Runoff from areas east of the Feather River flows into the river prior
to Nicolaus. However, runoff from the west side of the Feather River largely
drains into the East Canal and enters the Sacramento River via the Sacramento
Slough. In effect the entire dormant spray area between the Sacramento
and Feather Rivers drains into the Sacramento River through Karnak. In
past studies, diazinon levels have reached as high as 5 ppb in the Sacramento
Slough (personal communication, Chris Foe, Central Valley Regional Water
Quality Control Board, 1996). Toxicity has been found at Gilsizer Slough,
which drains some of the area west of the Feather River and flows into
the East Canal system. Ceriodaphnia dubia mortality was 100% in
five of the seven consecutive weekly samples and appeared related to levels
of pesticides detected in four cases (Foe and Sheipline, 1993).
In this study we will look at acute toxicity to C. dubia in a
small watershed where the discharging waters do not contain major inputs
from municipal or industrial sources. We will also investigate the potential
for chronic toxicity in a section of the Sacramento River downstream of
major dormant spray insecticide inputs in the watershed. Long term monitoring
of acute and chronic toxicity will help scientists at the Department of
Pesticide Regulation evaluate the effectiveness of programs designed to
decrease the runoff of dormant spray insecticides.
The objective of this study is to monitor the levels of chlorpyriphos,
diazinon, methidathion and the occurrence of acute and chronic toxicity
in the Sacramento River watershed during the dormant spray season. A companion
study will be established to monitor pesticide levels and toxicity in the
San Joaquin River.
This project will be conducted by the Environmental Hazards Assessment Program (EHAP) under the general direction of Don Weaver, Senior Environmental Research Scientist (Supervisor). Key personnel are listed below:
Project Leader: Craig Nordmark
Field Coordinator: Dave Kim
Senior Scientist: Lisa Ross
Study Design/Data Analysis: Terrell Barry
Contractor (Toxicity Tests): Charlie Huang, California Department of Fish and Game
Chemist: Jean Hsu, Hsiao Feng, California Department of Food and Agriculture
Agency and Public Contact: Pat Dunn
Questions concerning this project should be directed to Pat Dunn at phone (916) 324-4100,
Fax (916) 324-4088
IV. STUDY PLAN
Sampling for acute toxicity will be conducted from a bridge across the
East Canal at the Karnak pumping station, as this site receives water that
is predominantly agricultural (Figure 4). Sampling for chronic toxicity
will be conducted on the Sacramento River from the Bryte water intake platform
as this site receives discharge from all the major agricultural tributaries
(Figure 4) but is above the discharge of the largely non-agricultural American
River and the urban runoff of the City of Sacramento. Discharge records
are available for both the Karnak and Bryte sites from nearby gauging stations.
This information will be used to correlate any changes in chemical concentrations
to fluctuations in flow and may be useful for modeling efforts should they
Monitoring will commence prior to the onset of the dormant spray season
(late November/early December 1996) and continue through the second week
of March 1997. Background samples will be collected for one week, beginning
prior to dormant spray applications, then monitoring will resume once applications
have begun and continue until no later than March 28, 1997. Additional
data collection will include in-situ measurements of water pH and
temperature, dissolved oxygen, and specific conductance.
V. SAMPLING METHODS
Acute toxicity sampling will be conducted twice per week at Karnak on
Monday and Wednesday. Sampling for chronic toxicity will be conducted weekly
on the Sacramento River at Bryte. One chronic sample constitutes the collection
of samples on days zero, two and four of each week (e.g. Monday, Wednesday
and Friday). Water collected on those days will be delivered the following
day to the laboratory for testing and sample renewal. Chemical analysis
will be performed on each sample collected for both acute and chronic tests.
Selected OP and CB pesticides will be analyzed in three analyses (Table
At each sampling site, water will be collected from as close to center
channel as possible using a depth-integrated sampler (D-77) with a 3-liter
Teflon® bottle and nozzle. Sampling at the Karnak site may utilize
a grab pole from the river bank when bridge access is deemed unsafe. The
grab pole will consist of a Teflon® or a glass bottle at the end of
a three meter pole. Surface water sub-samples will be composited temporarily
in a stainless steel container until the appropriate volume of water has
been collected. The composited sample will be stored on wet ice until delivered
to the processing facility at West Sacramento. Immediately upon arrival
at the processing facility, the composite sample will be split into 1-liter
amber glass bottles, using a Geotech® 10-port splitter, then sealed
with Teflon® lined caps. The organophosphate and carbamate chemical
analysis samples will be preserved by acidification with 3N hydrochloric
acid to a pH between 3.0 to 3.5. Most OP and CB pesticides are sufficiently
preserved at this pH with the exception of diazinon. Therefore, diazinon
will be analyzed from a separate, unacidified, split sample. Samples submitted
for toxicity tests will not be acidified. Sufficient water will be collected
at each sampling event to provide approximately three liters for chemical
analysis, two liters for each toxicity test, and any additional water required
for quality control (QC) samples.
Split samples for chemical analysis will be transported on wet ice to
the California Department of Food and Agriculture (CDFA) Center for Analytical
Chemistry within three days. Split samples for toxicity testing will be
delivered on wet ice to the California Department of Fish and Game (CDFG)
Aquatic Toxicity Laboratory within 24 hours. CDFG will measure and record
other parameters of the split samples including totals of ammonia, alkalinity,
hardness, and specific conductivity as part of their toxicity testing.
VI. TOXICITY TESTING AND CHEMICAL ANALYSIS
Toxicity testing conducted by CDFG Aquatic Toxicity Laboratory will
follow current USEPA procedures using the cladoceran Ceriodaphnia dubia
(U.S. EPA, 1993). Acute toxicity will be determined using a 96-hour,
static renewal bioassay in undiluted sample water. Chronic toxicity will
be determined using a 7-day bioassay of undiluted sample water with C.
dubia and will follow current USEPA guidelines (U.S. EPA, 1994). For
example, test organisms used in chronic testing will be subjected to sample
water from day zero on the following day (day 1). Sample water collected
on days two and four will then replace test water on days three and five,
respectively. All bioassays must commence within 36 hours of sample collection.
Data will be reported to the project leader as percent survival on each
day for the duration of the tests.
Chemical analysis will be performed by CDFA Center for Analytical Chemistry.
The reporting limit will be the lowest concentrations of analyte that the
method can detect reliably in a matrix blank. The reporting limits for
this study are listed in Table 1. Chemical analytical methods will be provided
in the final report. The total number of samples is presented below.
Number of Toxicity Tests
2 acute tests per week, 12 weeks of study 24
1 chronic per week, 12 weeks of study 12
Additional Toxicity Testing Quality Control- see Barry (Protocol
Number of Chemical Analysis
3 (OP, CB, and diazinon) per acute test
3 analyses X 2 acute samples/week X 12 weeks 72
3 (OP, CB, and diazinon) per chronic sampling event
3 analyses X 3 chronic sampling events/week X 12 weeks 108
intra-laboratory comparison 18
Total number of chemical analysis samples 198
VII. QUALITY ASSURANCE/QUALITY CONTROL
To determine the variances within the primary laboratory, a quality
assurance plan has been developed for this study (Barry, 1996). Briefly,
additional samples from the acute toxicity monitoring site will be submitted
as splits along with the field samples for intra-laboratory comparison.
Also, two split samples from the acute toxicity monitoring site will be
submitted to a second laboratory by the Central Valley Regional Water Quality
Control Board (CVRWQCB). These splits will be tested at a laboratory of
their choice, which may not be accredited by the California Department
of Health Services. Comparability of the CVRWQCB results to those from
CDFG will be based on analysis of the toxicity methods used.
Quality control will be conducted in accordance with Standard Operating
Procedure QAQC001.00. Ten percent of the total number of primary analyses
will be submitted with field samples as rinse blanks, matrix blanks, and
blind matrix spikes. An additional two split samples from the Karnak site
will be given to the CRWQCB, Central Valley Region, for chemical analysis.
These two samples will be collected on the same days as the CRWQCB toxicity
VII. DATA ANALYSIS
Toxicity data will be used to establish baseline information on the
occurrence of acute or chronic events at these sites. A correlation matrix
will be established to identify potential relationships between measured
environmental parameters, discharge, toxic events, and chemical concentrations.
Measured concentrations will be compared to various established water quality
parameters including Quantitative Response Limits (QRL) and both acute
and chronic LC50s for C. dubia, to aid in interpretation of toxicity
test results. Analysis will also be made comparing the timing of samples
collected to storm events to examine the possibility that peak concentrations
may have been higher than the maximums observed. Further analysis may include
logistic regression, depending on preliminary analysis results.
|Site Survey and Selection||September 1996|
|Field Sampling||Late November/ early December 1996 and application onset through March 28, 1997|
|Summary Memo||May 1997|
|Draft Report||August 1997|
Barry, T.A. 1996. Protocol for obtaining a preliminary characterization of intra laboratory precision of acute toxicity tests performed on ambient water samples. California EPA/Department of Pesticide Regulation, Environmental Hazards Assessment Program. November, 1996.
California State Lands Commission (CSLC), 1993. California's rivers - A public trust report. Second Edition. California State Lands Commission, Sacramento, CA.
Foe, C. and R. Sheipline, 1993. Pesticides in Surface Water From Applications on Orchards and Alfalfa During the Winter and Spring of 1991-92. California Regional Water Quality Control Board, Central Valley Region, Sacramento, California. February 1993.
Friebel M.F., K.L. Markham, S.W. Anderson and G.L. Rockwell, 1995. Water Resources Data, California, Water Year 1994. Volume 4. U.S. Geological Survey Water-Data Report CA-94-4. Sacramento, California
Gorder, N. K.N. and J.M. Lee, 1995. Information on Rice Pesticides Submitted to the California Regional Water Quality Control Board Central Valley Region. Environmental Hazards Assessment Program, Department of Pesticide Regulation, Sacramento, California. December 28, 1995
MacCoy, D., K.L. Crepeau, and K.M. Kuivila. 1995. Dissolved pesticide data for the San Joaquin River at Vernalis and the Sacramento River at Sacramento, California, 1991-94. U.S. Geological Survey Rep. 95-110. U.S. Gov. Print. Office, Washington DC.
Nordmark, C., 1995. Preliminary Results of the Four River Monitoring Study, Sacramento River, November 1993-November 1994. Memorandum to Roger Sava, Environmental Hazards Assessment Program. Department of Pesticide Regulation, Sacramento, California. June 22, 1995.
Reynolds, F.L., T.J. Mills, R. Benthin, and A. Low. 1993. Restoring Central Valley streams: A plan for action. California Department of Fish and Game, Sacramento, CA.
U.S. Environmental Protection Agency. 1993. Methods for measuring the acute toxicity of effluents and receiving waters to freshwater and marine organisms. 4th ed. EPA/600/4-90/027F. August 1993.
U.S. Environmental Protection Agency. 1994. Short-term methods for estimating the chronic toxicity of effluents and receiving waters to freshwater organisms. 3rd ed. EPA-600-4-91-002. July 1994.
Zalom, F.G., R.A. Van Steenwyk, W.J. Bently, R. Coviello, R.E. Rice,
W.W. Barnett, C. Pickel, M.M. Barnes, B.L. Teviotdale, W.D. Gubler, and
M.V. McKenry. 1995. Almond pest management guidelines. University of California,
Division of Agriculture and Natural Resources, UCPMG Publication 1.
Table 1. California Department of Food and Agriculture, Laboratory Services
Branch: organophosphate and carbamate pesticide screens for the Sacramento
River toxicity monitoring study.
in Surface Water by GC
|N-Methyl Carbamate in Surface
Water by HPLC
Method: HPLC/Post Column-fluorescence
1) Diazinon will be analyzed from a separate, unpreserved, split sample. Other chemical samples will be preserved with 3N HCl to a pH of 3-3.5 to retard analyte degradation. See text.