# San Francisco Estuary Regional Monitoring Program for Trace Substances

SFEI Contribution 392

February 2005

San Francisco Estuary InstituteTitle Author San Francisco Estuary Institute



# Aquatic Pesticide Monitoring Program

Final Report

Geoffrey S. Siemering

Jennifer Hayworth

Aroon Melwani

# Aquatic Pesticide Monitoring Program

Final Report

Geoffrey S. Siemering

Jennifer Hayworth

Aroon Melwani

San Francisco Estuary Institute

7770 Pardee Lane, 2 nd 

# Floor

Oakland, CA 94621

February 2005

# This report should be cited as;

Siemering, G., Hayworth, J., and Melwani, A. 2005

. Aquatic Pesticide

Monitoring Program Final Report. SFEI Contribution Number 392. San

Francisco Estuary Institute, Oakland, CA.

# i 

# TABLE OF CONTENTS

EXECUTIVE SUMMARY .............................................................................................. 1

INTRODUCTION............................................................................................................. 5

B ACKGROUND 

# .................................................................................................................. 5

M ANAGEMENT AND 

# A SSESSMENT 

# Q UESTIONS 

# ................................................................. 7

O RGANIZATION 

# ................................................................................................................ 9

MONITORING PROGRAM......................................................................................... 11

T ARGET 

# P ESTICIDES 

# ....................................................................................................... 11

S ITE 

# S ELECTION 

# ............................................................................................................. 13

SAMPLING STRATEGY.............................................................................................. 14

A

NNUAL 

# G OALS 

# ............................................................................................................. 15

R EFERENCE 

# L OCATIONS 

# ................................................................................................. 17

S AMPLE 

# C OLLECTION 

# M ETHODS 

# ................................................................................... 20

D ATA 

# M ANAGEMENT 

# ..................................................................................................... 20

A PPROACH TO 

# R ISK 

# A SSESSMENT 

# .................................................................................. 21

Sediment Quality Triad Approach ............................................................................ 21

Risk Quotient Calculation......................................................................................... 22

RESULTS ........................................................................................................................ 24

2,4-D ............................................................................................................................. 24

C OPPER 

# S ULFATE 

# ........................................................................................................... 27

C HELATED 

# C OPPER 

# ........................................................................................................ 32

D IQUAT 

# D IBROMIDE 

# ...................................................................................................... 34

F LURIDONE 

# .................................................................................................................... 36

G LYPHOSATE 

# ................................................................................................................. 40

M ETHOPRENE 

# ................................................................................................................ 41

T RICLOPYR 

# .................................................................................................................... 43

CONCLUSIONS ............................................................................................................. 44

MANAGEMENT AND ASSESSMENT QUESTIONS REVISITED........................ 48

REFERENCES................................................................................................................ 50



# LIST OF TABLES

Table 1. Steering Committee Organization Member List................................................. 10

Table 2. Science Advisory Committee Members ............................................................. 10

Table 3. Pesticide Ranking Table ..................................................................................... 13

Table 4. Sampling frequency, collection order, and locations.......................................... 18

Table 5. APMP Sampling Sites ........................................................................................ 18

Table 6. Threshold Values Applied in Chemistry Evaluation after Siemering (2004).... 22

Table 7. Aquatic Animal and Plant Levels of Concern .................................................... 23

Table 8. Peak Concentration Risk Quotient Calculations for 2,4-D Application............. 25

# ii Table 9. Peak Concentration Risk Quotient Calculations for Surfactant (R-11) during 2,4-

D Application............................................................................................................ 25

Table 10. Sediment Quality Trend Calculations for 2, 4-D (DMA)................................. 26

Table 11. Summary of 2, 4-D (DMA) Sediment Quality Trend Data .............................. 26

Table 12. Water Risk Quotient Calculations for Copper Sulfate Applications (Reservoir

System) ..................................................................................................................... 27

Table 13. Sediment Quality Trend Calculations for Copper Sulphate ............................. 29

Table 14. Summary of Copper Sulphate Sediment Quality Trend Data........................... 30

Table 15. Water Risk Quotient Calculations for Chelated Copper Applications (Irrigation

Canal Systems).......................................................................................................... 32

Table 16. Sediment Quality Trend Calculations for Chelated Copper ............................. 33

Table 17. Summary of Chelated Copper Sediment Quality Trend Data .......................... 33

Table 18. Water Risk Quotient Calculations for Diquat Dibromide Applications........... 35

Table 19. Peak Risk Quotient Calculations for Fluridone Application at MID Main Canal

................................................................................................................................... 37

Table 20 Sediment Quality Trend Calculations for Fluridone.......................................... 38

Table 21 Summary of Fluridone Sediment Quality Trend Data....................................... 38

Table 22. Risk Quotient Calculations for Surfactant (R-11) during Glyphosate

Application at Doris Drain........................................................................................ 40

Table 23. Peak Concentration Risk Quotient Calculations for Methoprene Application. 42

Table 24. Risk Quotient Calculations for Surfactant during Triclopyr Application......... 43



# LIST OF FIGURES

Figure 1. APMP Sampling Locations. .............................................................................. 19

Figure 2. Typical Sampling Plan for an Individual Site ................................................... 20

# Aquatic Pesticide Monitoring Program

Final Report



# 1 

# EXECUTIVE SUMMARY

The APMP collected data during three aquatic pesticide application seasons

which indicated that widespread acute ecosystems impacts will not occur from aquatic

pesticides applied according to their label requirements. However, risk quotient

exceedances and sediment quality triad calculations indicate that significant questions

remain concerning potential localized acute impacts and chronic impacts. For most

pesticides, further risk characterization is indicated.

Additionally, surfactants (frequently added to pesticides by the applicator

immediately prior to application) may be an order of magnitude more toxic than the

active ingredient pesticide and may possibly be endocrine disrupting substances. Little

information is required for registration of surfactants by either USEPA or California

Department of Pesticide Regulation. In some cases, surfactants of the same chemical

class are sold premixed with the active ingredient pesticide for terrestrial formulations,

but for aquatic uses the surfactant is removed from the product. There is a significant

need for additional risk characterization of surfactants.

The three years of data gathered by the APMP should only be used for screening

purposes in order to identify where further risk characterization or research may be

needed. Definitive conclusions cannot be drawn from this data due to the small sample

number, the variety of application scenarios, and the disparate water body types

monitored. APMP generated chemical characterization, toxicity, and bioassessment data.

The chemical characterization and toxicity data generated can be used for screening

purposes. In complex field situations, bioassessments require multiple years of data

before preliminary conclusions can be drawn from them. Concurrent data collection and

analysis of all three data types (chemical, toxicity, and biological) provides important

integrative information for ecosystem risk evaluation.

Specific conclusions concerning individual pesticides:

2,4-D

Monitoring of 2,4-D (in the 2,4-D dimethylamine salt formulation) with added

surfactant showed no toxicity to standard EPA three species was observed nor did risk

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Final Report



# 2 quotients indicate the need for further information. Vitellogenin induction laboratory

experiments indicate that 2,4-D may cause endocrine disruption at legal application rates.

The vitellogenin induction studies indicate the need for further study of the

aquatic 2,4-D formulations and their primary breakdown products. This level of research

should not be expected from entities conducting compliance monitoring.

Acrolein

Because of acrolein’s rapid volatilization, work focused on development of a field

sampling method that would allow for accurate determination of the pesticide in water.

Current standard environmental sampling methods are inadequate for sampling of

acrolein treated water and result in unreliable analytical results.

Refinement of the sampling methodology began in 2003. Results indicate that the

method developed performs well at low acrolein water concentrations, making it possible

to determine acrolein residue values.

Due to acrolein’s rapid volatilization, it is currently not possible to conduct

standard water toxicity tests on it. Because of its’ extremely low Lowest Observable

Effect Concentration (LOEC) values, the detectable presence of acrolein indicates that

very high mortality to EPA water and sediment toxicity test species can be assumed.

The development of diagnostic response tests (i.e. phytomonitoring, sentinel

bivalves and fish, etc.) were explored and additional work is warranted. These tests have

the potential to provide a low cost, low tech method of detecting acrolein outside of

designated treatment areas.

Copper Sulfate

Copper sulfate applications were monitored in three reservoirs. Toxicity to

juvenile trout and Ceriodaphnia following application was observed. Peak concentration

risk quotients showed acute and chronic U.S. EPA Office Pesticide Programs Levels-ofConcern (LOC) exceedances.

In the reservoir treated with granular copper sulfate applications, significant

mortality was observed in Ceriodaphnia and juvenile trout water toxicity tests

immediately after application within the treatment area. Mortality and growth inhibition

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# 3 was also observed in a number of the sediment samples. Sediment copper concentrations

at many sites exceeded a published Hyallela LC50 value. However, the variable toxicity

results observed in the sediments indicates that the majority of the copper is not

bioavailable.

These findings indicate the need for further risk characterization associated with

copper sulfate applications.

Chelated Copper

Chelated copper pesticides were monitored during applications in two irrigation

canal systems. One system used a product of mixed copper ethanolamines and the other

the same product of mixed copper ethanolamines in an emulsified formulation. Chelated

copper formulations are likely to have distinct behavior from each other and copper

sulfate in aquatic environments based on the chelating agent as well as other adjuvants. It

should be noted that copper carbonate is the active ingredient in other chelated copper

pesticide products and no monitoring of copper carbonate based pesticides was

conducted.

In both systems where monitoring occurred, the water samples were almost

uniformly toxic in pre-application and post application. Therefore, no definitive

conclusions can be drawn about the toxicity of mixed copper ethanolamines. The

sediment quality triad calculations indicate the possibility of copper impacts to the

system.

Further risk characterization associated with chelated copper applications is

warranted.

Glyphosate

Glyphosate was monitored at several locations. No toxicity was found to be

associated with glyphosate applications. Glyphosate is very often applied with a

surfactant, which may have much higher toxicity than the active ingredient.

Based on risk quotient calculations and toxicity data, no further risk

characterization associated with glyphosate only applications is warranted. Risk

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# 4 characterizations are warranted when a surfactant is used in conjunction with the

glyphosate.

Diquat Dibromide

Diquat dibromide was sampled at two locations, one small pond and a Delta

slough. Diquat risk quotients almost uniformly exceeded LOC’s at all sampling periods

in the Delta slough (including preapplication) and at one hour after application in the

pond. Diquat may be applied with a surfactant which may exhibit much higher toxicity

than the active ingredient. Diquat sediment concentrations were not considered as diquat

is irreversibly adsorbed to sediments and is thereafter not bioavailable.

Toxicity test and risk quotient results indicate the need for further risk

characterization.

Fluridone

Fluridone (applied in pellet or liquid form) was not found to be definitively toxic

to or have LOC exceedances for the standard USEPA three species water or sediment

amphipod organisms. The peak concentration risk quotient for Stonewort did exceed an

acute LOC. Fluridone was found to cause sublethal toxicity (decreased shoot and root

length) to Typha latifolia

. This would indicate a potential for impacts to nontarget plants.

Further risk characterization of fluridone impacts on nontarget plants is

warranted. There is also cause for concern over development of genetic resistance to

fluridone which is emerging in plant populations in Florida.

Methoprene

Monitoring for methoprene is challenging because it is commonly applied to

environments that do not lend themselves to traditional water and sediment sampling and

testing methods. These systems usually have extremely shallow water and highly anoxic

sediments which impede standard toxicity tests. In situ and laboratory toxicity tests were

completed, but the results were inconclusive. From the one site monitored for

methoprene, water and porewater risk quotients did not exceed criteria. However, further

risk characterization is needed. Methoprene was persistent in marsh sediments, up to the

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# 5 ppm level, for several weeks. Little methoprene sediment toxicity data could be located

in the literature.

Future work is warranted to further characterize the risk of methoprene in

sediments. Additional studies may also be warranted due to the common simultaneous

application of methoprene and Bti.

Triclopyr

Triclopyr was monitored at one application. Triclopyr peak concentration risk

quotients show no LOC exceedances. Triclopyr is often applied with a surfactant, which

may exhibit higher toxicity than the active ingredient. Further risk characterizations are

warranted since a surfactant was used with triclopyr.

Nonionic surfactants

The most commonly used surfactants at APMP monitoring sites were Target

Prospreader Activator and R-11. Both are nonylphenolethoxylate based surfactants.

Peak concentration risk quotients indicate exceedances of LOCs for a wide range of

animal species including Delta Smelt and Sacramento Splittail. Vitellogenin induction

experiments in Rainbow trout indicate that these nonylphenol surfactants can be an

endocrine disruptor at application rates. There are a wide range of surfactants available,

each one having a different toxicological profile. Due to their classification as an

adjuvant, very little data is required for registration. However, our results suggest that

further risk characterizations are warranted for all surfactants.



# INTRODUCTION

Background

In January 2002, the San Francisco Estuary Institute (SFEI) began the

development and implementation of a statewide aquatic pesticide monitoring program

(APMP) with funding from the California State Water Resources Control Board

(SWRCB). The APMP was funded to evaluate the potential water quality impacts

associated with the application of aquatic pesticides because of a series of court decisions

and a legal settlement. Aquatic pesticides fall into two distinct groups, herbicides and

mosquito vector control compounds. These are compounds that have registration labels

# Aquatic Pesticide Monitoring Program

Final Report



# 6 that explicitly allow direct application to waterbodies. Pesticides applied for terrestrial

use that reach waterbodies (i.e. through runoff or spray drift) were not studied as part of

this project.

In 2001, a ruling by the U.S. Ninth Circuit Court of Appeals, in Headwaters, Inc.

v. Talent Irrigation District

, stated that registration and labeling of aquatic pesticides

under the federal pesticide law (Federal Insecticide, Fungicide, and Rodenticide Act or

FIFRA) does not preclude the requirement to obtain coverage under a National Pollutant

Discharge Elimination System (NPDES) permit prior to discharging such pesticides into

waters of the United States (243 F.3d 526 (9th Cir. 2001). Headwaters, Inc. v. Talent

Irrigation District, the U.S. Court of Appeals for the Ninth Circuit). The SWRCB issued

an emergency NPDES permit in July 2001. This permit was challenged in California

state court by the environmental advocacy group Waterkeepers of Northern California on

the grounds that it did not provide sufficient protection of the environment ( Waterkeepers

Northern California v. State Water Resources Control Board

, Alameda County Superior

Court No. 2001-022050). This legal challenge coupled with that of the Talent decision

rendered the legal application of aquatic pesticides in California impossible for the 2001

application season (generally April-September). This legal challenge was settled with an

agreement that the SWRCB would fund aquatic pesticide research and monitoring to

provide the state with rigorously reviewed scientific information to develop an acceptable

general NPDES permit upon expiration of the emergency permit in January 2004. In the

settlement SFEI, a non-profit organization with a Board of Directors including scientists,

environmentalists, regulators, and dischargers to the Bay, was designated as the scientific

entity responsible for the implementation of the APMP. The settlement mandated that

$1,950,000 be spent on aquatic pesticide monitoring and research and $600,000 exploring

nonchemical alternatives to the use of aquatic pesticides. The contract funding this

program states that,

“the objective of the APMP is to implement comprehensive monitoring

and special studies to evaluate the water quality impacts associated with

the application of aquatic pesticides and the non-chemical alternatives to

the use of aquatic pesticides. The primary focus shall be to provide

information to the SWRCB and Regional Water Quality Control Boards

(RWQCBs) to enable to SWRCB and RWQCBs to effectively regulate

discharges of aquatic pesticides to surface waters.”

# Aquatic Pesticide Monitoring Program

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# 7 In addition, the contract with SFEI specified that the follow studies be

undertaken:

1) Fate and transport of applied materials and breakdown products, including

residence time in the environment, mass loading of the pesticide, evaluation of

bioaccumulation.

2) Assessment of impacts to beneficial uses including: potential routes of

exposure, life cycle bioassessments on a range of species, biochemical and/or

physiological testing of sublethal effects including reproduction and growth.

3) Characterization of accumulation in sediments where a pesticide is suspected

of sediment accumulation.

4) Characterization of accumulation in organisms where persistence or

bioaccumulation of suspected.

5) Conduct community monitoring surveys including evaluation of nontarget

plants or animals, organism diversity and ecosystem integrity.

Management and Assessment Questions

While the legal settlement and initial contract gave general guidance, the exact

natural of the monitoring and research efforts were not detailed. To help direct the

monitoring effort development, Management and Assessment questions were derived at

the outset of the APMP. Management questions are overarching questions that need to

be answered in order to accomplish the project goals. Assessment questions are second

tier questions that address specific knowledge items that need to be determined to

adequately answer the Management questions. This Management and Assessment

question model for developing the program was used in order to provide a theoretical

framework that would keep the scientific work on track. These questions were referred

to throughout the project at all stages of planning and development.

The Management and Assessment questions developed for the APMP are as

follows (management questions in italic):

1. Which aquatic pesticides used in California have the highest “risk” of impacts to

people and the environment?

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# 8 a. What is the amount of each aquatic pesticide used?

b. What is the aquatic toxicity of each compound?

c. Where are the compounds being used?

d. When are the compounds being used?

e. What is their environmental fate and persistence?

2. What are the concentrations of the target aquatic pesticides in the environment

(water, sediment, and biota) adjacent to their application point?

a. What are the concentrations in the dissolved fraction and particulate

fraction (45 micron) of water?

b. What are the concentrations in sediment pore water?

c. What are the concentrations in bulk sediments?

d. What are the concentrations in the gonads of native fish?

e. What are the concentrations in the muscle tissue of native fish and

bivalves?

f. Are there wet-dry seasonal differences in concentrations?

3. Are the measured concentrations above existing effects thresholds?

a. Is the water or sediment toxic using Standard Bioassay Protocols?

b. Are there human health risks associated with water contact or eating fish

or shellfish?

4. Which locations have the highest “risk” of beneficial use impairment?

a. Should a sample of systems using pesticides be monitored?

b. Are there sensitive areas (i.e. wildlife refuges, wilderness areas, etc)

particularly at risk?

5. What is the degree of biological impacts to non-target biota from application and

exposure to aquatic pesticides?

a. Are population mortality rates elevated compared to a reference

population in ‘clean’ waters?

b. Is growth impaired?

c. Is reproduction impaired?

The Management and Assessment questions, generated through numerous

discussions, were used to develop a plan of action for monitoring aquatic pesticide use.

# Aquatic Pesticide Monitoring Program

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# 9 The monitoring plan ultimately developed attempted to address as many of the

assessment questions as possible within the fiscal and logistical constraints of the project.

The studies performed to evaluate potential pesticide impacts will hereafter be

referred to in general as monitoring. Monitoring to many in the scientific community

means to test or sample on a regular or ongoing basis. However, to avoid overly length

descriptive terms for the various studies conducted, this report will use the word

monitoring to mean “to keep track of systematically with a view to collecting

information.” The ‘monitoring’ performed during the APMP could be more precisely

described as case study investigations performed with a wide variety of scientific tools to

help inform the development of aquatic pesticide NPDES permits.

Organization

Due to the politically charged environment, SFEI established a consensusbuilding, stakeholder-driven process to oversee the work By having all interested parties

involved from the inception of the project and giving input throughout, it was possible to

achieve acceptance both of the methods used and data generated from the project.

To ensure scientific rigor, an external scientific peer review committee was

established to provide review and guidance for the project. Several focused workgroups

were formed to address questions relating to chemistry, toxicity, modeling and

bioassessments. The members of these workgroups were drawn from local academic

institutions, government laboratories, and private firms. Contract laboratories were

identified to perform the sample testing necessary. A mixture of university, government,

and private labs were selected according to their expertise.

Since the driving impetus for this project came from within the legal system, a

project Steering Committee composed of individuals from Federal and State agencies,

stakeholder groups, and public interest groups was assembled ( Table 1 ). Early in the

project, the monthly steering committee meetings focused on creating an organizational

structure for the APMP and guiding the development of the monitoring plans, later

quarterly meetings focused on discussing and resolving programmatic development

issues. The meetings were open to all interested parties as well as steering committee

members.

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# 10 Table 1. Steering Committee Organization Member List

Central Valley Regional Water

Quality Control Board California Farm Bureau

Federation California Department of Fish &

Game

US Dept. of Agriculture Monsanto Contra Costa Mosquito Vector

Control District

South San Joaquin Irrigation

D istrict DeltaKeeper US Fish & Wildlife Service

US EPA, Region 9 (WTR 5) Syngenta National Marine Fisheries Service

Association of CA Water

Agencies Ventura County Water Protection

District Orange County Public Facilities

Department

Bay Area Stormwater

Management Agencies

Association San Joaquin County Mosquito

Vector Control District EMC Environmental Consulting

Services.

California Dept. of Pesticide

Regulation Metropolitan Water District of

Southern California Solano Irrigation District

California Dept. of Boating and

Waterways Marin Municipal Water District State Water Resources Control

Board

San Francisco Baykeeper Sutter County Agriculture California Dept of Health Services

Vector-Borne Disease Section

Los Angeles Dept of Water &

Power Marin Municipal Water District California Dept of Food and

Agriculture

USEPA Region 9 California Water Quality Coalition



# The external peer review panel, hereafter referred to as the Science Advisory

Committee (SAC), was composed of five scientists who are recognized as experts on

pesticides and their effects. This committee provided independent peer review for APMP

workplans and findings. This committee met at the outset of the project and then annually

to review the results and upcoming plans. The SAC members were also consulted

periodically as technical questions arose and received written updates quarterly. SAC

members are listed in Table 2

.

Table 2. Science Advisory Committee Members

Name Affiliation

John H. Rodgers Clemson University

Institute of Environmental Toxicology

Lenwood Hall University of Maryland

Agricultural Experiment Station

Wye Research and Education Center

Michael Anderson, University of California-Riverside

Department of Environmental Sciences

Jay Gan. University of California-Riverside

Department of Environmental Sciences

R. David Jones U.S. Environmental Protection Agency

Office of Pesticide and Toxic Substances

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# 11 

# MONITORING PROGRAM

The monitoring program SFEI was charged with implementing was intended to

have wide spatial coverage, investigate behavior of all pesticides currently in use in

California, determine potential impacts in the range of waterbody types receiving

applications, and provide information on aquatic pesticides free of any additional

confounding factors. It was agreed early in the program, that the length of time allowed

and the funding provided were insufficient to accomplish the three goals. A tiered

approach was developed to achieve a balance between program goals and what was

practically achievable. In addition, ranking schemes and selection criteria were

developed to guide site selection, pesticide priority, and monitoring methods.

The tiered approach developed to help focus the implementation of the aquatic

pesticide monitoring efforts is as follows:

Tier 1. Information-based research. Conduct a literature review to identify likely

pesticide/ environmental couplings where accumulation is likely or unlikely,

determine annual usage from California Department of Pesticide Regulation

database, and develop a permit holder database to identify best possible candidate

monitoring sites

Tier 2. Field monitoring. Conduct sampling to confirm presence or absence of

pesticide in aquatic ecosystems, potential water and sediment toxicity, and

impacts to nontarget invertebrate populations.

Tier 3. Special studies. Where tier 1 & 2 results indicate, conduct special projects

to address technical sampling issues or more fully characterize specific aquatic

pesticide environmental impacts.

Target Pesticides

Potential target pesticides were ranked based on the following criteria: aquatic

uses, amount used, common usage, toxicity/risk, public concern, reliable analytical

methods, and regulatory significance (Table 3). Information on these aquatic pesticides

was collected through a detailed literature review conducted by SFEI (Siemering et al

# Aquatic Pesticide Monitoring Program

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# 12 2003), from the California Department of Pesticide Regulation Pesticide Use Report

database, and from the professional opinions of a subset of steering committee members.

The mosquito vector control compounds were by and large not addressed by the

APMP due to the difficulty in finding suitable sampling locations, the lack of adequate

analytical methods, and infrequent or “emergency” use of many compounds. The three

primary mosquito control insecticides used are Bacillus Thuringiensis israelensis (BTi),

methoprene and larvicidal oils. There are no standard analytical methods for BTi and no

toxicity test methods for methoprene, due to its rapid degradation. Larvicidal oils vary in

content and are also similar to other petroleum products frequently found in the

environment.

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# 13 Table 3. Pesticide Ranking Table

Chemical Selectivity Toxicology Phys Chem Perception Total

Score Final

Ranking

1

– low risk

5

– high risk Indirect Ecosys

tem Terres

trial Human Half

-life Kow Mobilit

y 

# Sum of

criteria

scores

Acrolein 5 4 5 2 (4) 1 1 5 5 32 1

Copper (total

and ionic) 2 4 4

- 5 1

– 2 1 2 1 

# 2 2

– 3 5 26 2

2,4-D (salt) 1 (3) 2 - 3 1 – 2 1 2 3 2 3 – 4 20 3

Endothal 2 4 2 1 (1) 2 (3) (3) 2 19 4

Fluridone 3 2 1 1 1 3 2-3 3 1 – 2 19 4

Triclopyr 1 4 2 1 (1) 2 (3) (3) 3 – 4 19 4

Diquat

dibromide 3 4 2

- 3 1 1 1 1 1 3 18 5

Glyphosate 5 1 1 1 1 1 1 1 (4) 16 6

1 

# Bioavailable form

() estimated values



# Site Selection

The regulatory areas that were considered for sampling included irrigation supply

systems, drinking water reservoirs, exotic weed control (canals and coastal), flood control

and drainage, and storm water and recreational impoundments (golf courses and parks).

A ranking system was developed with regard to system complexity. Monitoring was

conducted in increasingly complex water bodies as sampling methods and staff

experience and site knowledge were developed to adequately accommodate the specific

system characteristics. The complexity of water systems were ranked as follows (in order

of increasing complexity): irrigation district canals< storm water canals and small

streams< lakes or reservoirs< Sacramento/ San Joaquin Delta< San Francisco Bay or

other coastal estuaries.

Within each water body category, the sampling sites selected for monitoring were

based on the following criteria:

1. Representative of typical applications of identified pesticide of interest,

2. Limited, or well-characterized inputs,

3. Existence of chemical analysis methods with detection limits sufficient for

ambient environmental monitoring,

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# 14 4. Representative of a typical application by a pesticide user group (e.g., a municipal

drinking water district, a irrigation district, a county public works department, and

county agriculture office).

In 2002, a database of aquatic pesticides NPDES permit holders was created.

From this database, individual permit holders were identified whose water bodies would

provide the greatest amount of spatial coverage and represent the greatest number of user

groups and pesticides. These permit holders were then contacted to ascertain interest in

participating with APMP and to gather further details on the systems receiving

applications. Only one permit holder was not willing to participate. The final site

selections were made after site visits and evaluations by APMP staff. While the greatest

number of sites possible were sampled, the number is still small in comparison to the

total number of sites receiving aquatic pesticide applications within California.



# SAMPLING STRATEGY

Combining the assessment questions with the tiered approach and ranking criteria,

the specific APMP monitoring objectives at each sampling site were determined to be:

1. Determine fate and transport of applied chemicals.

2. Evaluate the acute lethal effects of pesticides on aquatic organisms through

toxicity testing.

3. Evaluate the sublethal effects of pesticides on aquatic organisms. This entailed

assessment of potential biochemical and/or physiological effects by toxicity

testing.

4. Evaluate the effects of pesticides on non-target aquatic biological communities.

5. Determine the effect of repeated pesticide exposure on benthic

macroinvertebrates. Community structure elements to be assessed include

taxonomic, functional, and tolerance composition, along with abundance and

diversity measures.

6. Determine the effects of pesticide applications on the benthic macrophyte

community and associated epiphytic macroinvertebrates. Effects could include

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# 15 pesticide drift and changes in water column chemistry from decomposition of

aquatic vegetation. Community structure elements to be assessed for benthic

macrophytes include taxonomic composition, frequency distribution, coverage,

abundance, and diversity measures. Epiphytic macroinvertebrates were analyzed

for the same community structure elements as the benthic invertebrates.

7. Determine the effect of pesticide exposure on phytoplankton communities.

Community structure elements to be assessed include taxonomic composition,

abundance, and diversity measures.

Annual Goals

In 2002, the first year of the project, the sampling was mandated by the legal

settlement to begin no later than July 1 st



# . To accomplish that goal, sampling was limited

to preliminary studies of pesticide fate at selected sites for high priority pesticides.

Measurements included chemistry water, tissue and sediment samples and sediment and

water sampling.

Year two incorporated a triad sampling approach recommended by the EPA

(Barbour et al. 1999). This included synoptic sampling for chemistry, toxicity, and

biological assessments data. Bioassessments focused on communities that are widely

recognized as appropriate biological indicators of contaminant impacts: aquatic

macroinvertebrates, macrophytes, and algal communities (US EPA 2003). Due to the

diverse nature of the target pesticides and water-body types studied, the type of

bioassessments conducted were specifically adapted for each pesticide sampling event.

However, where possible all studies were similarly designed and the data obtained is

directly comparable. The specific goals for the 2003 monitoring effort were: 1) to revisit

appropriate sites studied in Phase 1, 2) perform chemical analysis and toxicity testing for

all pesticides of interest, 3) expand the number of study sites, 4) implement

bioassessment studies all locations, and 5) begin special studies to fill gaps in knowledge

of target pesticide and selected adjuvant (surfactants) behavior.

2004 efforts focused on special studies to answer questions raised during the first

two years. The primary focus of these studies was nontarget organism impacts and

potential long term impacts.

# Aquatic Pesticide Monitoring Program

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# 16 It was decided that APMP’s monitoring goals would be most efficiently achieved

by closely coordinating with current aquatic pesticide users during their pesticide

application cycle. By closely tying the sampling events to a pesticide application, ‘worstcase’ scenarios could be investigated. Given the limited time and budget of the APMP,

looking at such worst-case scenarios was felt to be a prudent approach. During years two

and three, the ‘worst-case’ regime was augmented with longer term macroinvertebrate

and phytoplankton bioassessment studies. These bioassessment studies allowed for a

more comprehensive investigation into potential environmental impacts (chronic and

acute) of aquatic pesticide applications.

This “worst-case scenario” design explored the fate of pesticides applied at

normal field concentrations and yielded data on both acute and longer term pesticide

impacts. The sampling frequency enabled detection of potential biological responses as

macroinvertebrates, and to a lesser extent, phytoplankton and macrophytes responded to a

perturbation.

A diverse range of water-body types located throughout California were

monitored. The frequency and level of sampling varied because of pesticide and sitespecific issues (e.g. presence of other potential contaminants, availability of reference

sites). The pesticides monitored included acrolein, 2,4-D (dimethylamine), copper

sulfate, chelated copper (copper ethanolamine), diquat dibromide, fluridone, glyphosate,

methoprene, and triclopyr (triethlyamine). Due to the extremely volatile nature of

acrolein sampling for acrolein focused on developing field sampling methods to account

for this volatility. Endothal was initially identified as a pesticide of interest, however, due

to its limited use in California, no monitoring was conducted.

A temporally stratified study design was implemented to coincide with pesticide

application events. Samples were collected before pesticide application and at various

post application increments ( Table 4 ). We conducted quantitative sampling to enable

spatial and temporal statistical comparisons. Sampling locations throughout the state are

shown graphically in Figure 1

. A graphic representation of sampling at a single site is

shown in Figure 2

. Table 5 is a complete list of all locations sample.

# Aquatic Pesticide Monitoring Program

Final Report



# 17 Reference Locations

At each location where monitoring took place, a reference site was identified.

The ideal reference site would have been an identical water body immediately adjacent to

the treated water body that had never received applications. The closest to this ideal that

was found in the Marin Municipal Water District system.

The sites selected as reference sites were as similar as possible to the treated sites

as possible minus the application of pesticide. In flowing water bodies, this was often

immediately upstream of a treatment area. In lentic systems, an untreated portion of the

water body was selected. As with the treated sites, these reference sites often received

input from sources possibly containing contaminants in addition to the aquatic pesticide

applied. Every attempt was made to select sites with minimal uncharacterized inputs.

These sites served as reasonable reference locations for the chemistry and toxicity

studies.

However, for the benthic invertebrate studies, these reference sites were far from

ideal. Most of the systems in California to which aquatic pesticides are applied are manmade, heavily altered, or highly impacted. Sites which would have minimally disturbed

benthos are often remote and dissimilar to water bodies received treatment.

# Aquatic Pesticide Monitoring Program

Final Report



# 18 Table 4. Sampling frequency, collection order, and locations.

Sample collection frequency

P re-application

Initial Post-application (within 1-24 hrs) 1



# 2 weeks post

4-6 weeks post 2



# Order of Sample Collection

1. Physical Habitat Assessment

2. Water Quality Parameters

3. Macrophyte Survey

4. Sediment Parameters

5. Macroinvertebrate Assessments

1 

# Macrophytes and macroinvertebrates not collected at this time.

2 

# For long-term sampling of copper sulfate, fluridone, and glyphosate only.

Table 5. APMP Sampling Sites

Sampling Sites

Cooperating Permit Holder /Treated Sites /Control Site / Pesticide

Marin Municipal Water District / Bon Tempe and Nicasio Reservoirs / Lake Lagunitas / copper sulfate 1



# Cal. Dept. of Food and Agriculture / Costa Ponds / untreated pond / liquid fluridone 1



# U.S. FWS and Dept. of Boating and Waterways / Lower Stone Lake / Upper Stone Lake / glyphosate 1



# Sand Bay Isle Homeowners Association / Sand Bay Isle Ponds / diquat dibromide and copper sulfate

U.S. FWS and Dept. of Boating and Waterways / treated Stone Lake slough / untreated slough / 2,4-D

Solano Irrigation District / Byrnes canal / untreated canal section / chelated copper

Potter Valley Irrigation District / treated canal / untreated canal section / chelated copper

Big Bear Municipal Water District / treated lake area / untreated lake area / pelleted fluridone

Merced Irrigation District / Atwater Canal / untreated canal section / glyphosate

Merced Irrigation District / Main Canal / untreated canal section / liquid fluridone

Merced Irrigation District / LeGrande & Planada Canal / untreated canal section / acrolein

Merced Irrigation District / Livingston Canal / untreated canal section / acrolein

Ventura County Flood Control District / Doris Drain storm water canal / untreated section / glyphosate

Cal. Dept. of Food and Agriculture / Bear Creek / untreated creek section / triclopyr

Dept. of Boating and Waterways / Delta 7 Mile slough / untreated slough area / diquat dibromide

Cal. Dept. of Food and Agriculture / Clear Lake / untreated lake portions / pelleted fluridone

Cal. Dept. of Food and Agriculture / Anderson Pond / pretreatment / triclopyr

Contra Costa Mosquito VCD / Swanton’s Marsh / untreated marsh area / methoprene

1 

# Long-term study sites.

# Aquatic Pesticide Monitoring Program

Final Report



# 19 Figure 1. APMP Sampling Locations.

# Aquatic Pesticide Monitoring Program

Final Report



# 20 Figure 2. Typical Sampling Plan for an Individual Site



# Sample Collection Methods

Standard protocols for chemistry and toxicity sampling and handling have been

compiled in the Aquatic Pesticide Monitoring Program Quality Assurance Project Plan

(QAPP) (Yee et al. 2004). This document was reviewed by the USEPA Region 9 Quality

Assurance office. The bioassessment methods and results are detailed in Hayworth et al.

2004. These methods follow those developed by the California Department of Fish and

Game and were adapted for the specific systems being monitored.

Data Management

All digital data and information generated from sampling are stored at SFEI in a

California State Water Resource Control Board Surface Water Ambient Monitoring

Program (SWAMP) format. All data and reports are publicly available at SFEI’s

website.

# Aquatic Pesticide Monitoring Program

Final Report



# 21 Approach to Risk Assessment

Chemical characterization, toxicity tests and benthic and epiphytic test results

were reviewed for trends that may indicate impacts due to aquatic pesticide applications.

When sufficient data was available, we used the sediment quality triad approach for

evaluating pesticide-contaminated sediments proposed by Chapman et al. (1991) and

used in Canfield et al. (1994). In some cases, there was insufficient data to perform

sediment quality triad calculations. In these cases, risk quotients were calculated for a

range of test species. Where discrepancies occurred, they are highlighted in the text. The

ultimate goal of this data interpretation is to identify for regulators areas that may need

regulatory attention or additional research. These results in and of themselves can not

provide definitive information on a particular pesticide’s behavior in the environment.

Sediment Quality Triad Approach

The triad approach is an effects-based approach that integrates measures of

chemistry, sediment toxicity, and benthic community structure, to evaluate sediment

quality in aquatic and marine systems. Metrics used to evaluate chemistry were the

concentration of applied pesticide, in sediment (if available) and pore-water. Mean

growth and percent survival of Hyalella azteca (10-d exposure) were the preferred

metrics to evaluate whole-sediment toxicity. However, if these data were unavailable,

substituted animal or plant toxicity metrics were applied. The number of chironomid

genera and species richness were used to evaluate benthic community structure. We

chose to rank chemistry, toxicity, and benthos using procedures developed by Kreis

(1988) and used by Canfield et al. (1994). Accordingly, values for each individual

variable for all stations (included reference) were scaled proportionally between 0 and

100 (e.g. 100 is the highest toxicity measured). The toxicity rank was determined by

summing the ranks for both toxicity variables and re-ranking the results.

The criterion for evaluating chemistry was a concentration of pesticide or metal

that exceeded either the risk quotient for sediment or the toxicity endpoint for an aquatic

species in porewater (see Table 6 ). The criterion for elevated toxicity was a significant

decrease in either of the toxicity variables used, relative to the control. The criterion for

impacted benthos was either a Chironomidae genera richness or species richness value

that was significantly different from the mean of the respective reference stations. A

# Aquatic Pesticide Monitoring Program

Final Report



# 22 significant difference in benthos was tested using a two-sample t-test between each

treated station and all reference stations.

Table 6. Threshold Values Applied in Chemistry Evaluation after Siemering (2004).

Metal or Pesticide Sediment

Threshold Sediment

Threshold

References Pore-water

Threshold Porewater

Threshold

Reference

Copper Sulphate LC50 ( Hyallela

azteca )

- 262 μg/g Suedel et al 1996 LC50 ( H. azteca )

– 0.035 mg/l Suedel et al 1996

Chelated Copper LC50 ( Hyallela

azteca )

- 262 μg/g Suedel et al 1996 LC50 ( H. azteca )

– 0.035 mg/l Suedel et al 1996

Fluridone N/A EC50 (Stonewort)

– 0.20 mg/l Burkhart and

Stross 1990

2,4-D N/A LC50

( Chironomus

plumosus )

– 100

mg/l Washington, Dept.

of Ecology 2001



# Risk Quotient Calculation

Risk quotients were calculated according the method promulgated by the USEPA

(USEPA, 1998). These risk quotients are part of the first step of a four part risk

characterization process outlined in the ECOFRAM draft Aquatic Report (USEPA,

1999). This report states,

“The purpose of the tiered process is to provide a logical progression of tests and

risk assessment approaches to address the potential risks of toxicants to aquatic

systems. The common feature of all tiered regulatory processes is a progression

beginning with conservative assumptions and moving toward more realistic

estimates. Tiered processes tend to be cost effective in that they ensure that

resources are expended on pesticide product/issues meriting attention. ... The

tiers are differentiated primarily by the data available at that state in the risk

assessment process and the relative cost of achieving risk refinement appropriate

for that tier of analysis.”

Risk quotients were calculated in order to identify where additional risk

characterization work may be needed to fully explore potential impacts of aquatic

pesticides. They only indicate where additional information may be needed and, in and

of themselves, do not indicate impacts.

# Aquatic Pesticide Monitoring Program

Final Report



# 23 In order to integrate water exposure information with water toxicity information,

risk quotients (RQs) are calculated by dividing water chemical concentrations by an acute

or chronic ecotoxicity value: Toxicity Exposure RQ

= 

# (USEPA, 1998).

Exposure = an estimated environmental water concentration or actual water

concentration field data.

Toxicity = an accepted toxicity measurement (i.e. LC50, LD50, EC50, EC25,

NOEC, LOEC, or MATC).

The RQs calculated in this document used the highest pesticide concentration

experimentally determined during our monitoring of the applications of a particular

pesticide. The use of these peak values is appropriate for a Tier 1 risk characterization as

such a characterization is meant to be protective, not predictive, and is therefore based on

conservative (i.e. worst-case) assumptions about potential exposure and effects. If

possible risk is identified in a Tier 1 analysis, then a Tier 2 analysis (addressing the

probability and magnitude of effects on sensitive species using conservative exposure

scenarios) is indicated. Tier 2 analysis was not performed as part of this project.

The calculated RQs are then compared to a Level of Concern (LOC) determined

by the USEPA Office of Pesticide Programs (OPP). The specific LOCs for aquatic

animals and plants are shown in Table 7

. LOCs are unit less values that allow for simple

determination of possible exceedances of regulatory limits. An LOC exceedance is

indicative only of the need for further investigation of an application scenario.

Table 7. Aquatic Animal and Plant Levels of Concern

Risk Presumption RQ LOC

Acute Risk EC/LC50 or EC50 0.5

Acute Restricted Use EC/LC50 or EC50 0.1

Acute Endangered Species EC/LC50 or EC50 0.05

Chronic Risk EC/ MATC or NOEC 1



# The USEPA interprets exceedances of LOCs as follows:

Acute high risk : potential for acute risk is high; regulatory action may be

warranted in addition to restricted use classification

Acute restricted use : the potential for acute risk is high, but this may be mitigated

through restricted use classification

# Aquatic Pesticide Monitoring Program

Final Report



# 24 Acute endangered species : the potential for acute risk to endangered species is

high, but this may be mitigated through restricted use classification

Chronic risk : the potential for chronic risk is high; regulatory action may be

warranted

Values for standard toxicity test species will be used, as will values for any listed

species present. Where there are multiple toxicity values for the same test species, the

lowest value will be selected. The toxicity measurements used are from peer-reviewed

academic literature, FIFRA registration documents, or other government reports.

Risk quotients are also calculated for sediment pesticide concentrations where

toxicity values are available. However, the USEPA LOCs are not applicable to sediment

pesticide concentrations and there are no comparable regulatory values for sediment.



# Results

2,4-D

U.S. Fish and Wildlife Service employees applied the herbicide Weedar 64 (2,4-D

dimethylamine salt) mixed with R-11 surfactant (a nonylphenolethoxylate surfactant) to a

main stem slough of South Stone Lake within the Stone Lake National Wildlife Refuge

(SLNWR) on September 8, 2003. 2,4-D (DMA) and 2,4-D (BEE) are both registered for

aquatic use, but have different toxicological properties making it important to

differentiate between the compounds when reviewing data. Portions of South Stone Lake

are repeatedly treated with 2,4-D and surfactant during the summer and early fall to

control heavy infestations of water hyacinth ( Eichornia crassipes ). Different sections of

this lake are treated with glyphosate for hyacinth control. The 2,4-D is applied to the

emergent vegetation via an automated spray nozzle water pump system mounted on an

airboat. The study area was approximately 0.15-acres, densely covered by hyacinth, with

a sand/silt-consolidated substrate. The application rate at the site was 30 liquid ounces of

herbicide per 50 gallons water. The nonylphenol surfactant was added to the pesticide

tank mix.

Tables 10 and 11 summarize the sediment quality triad measurements for the 2,4-

D application at SLNWR. This data indicates that there is no evidence of pesticide

# Aquatic Pesticide Monitoring Program

Final Report



# 25 induced degradation at either of the sampling locations. In addition, no LOCs were

exceeded by the maximum 2,4-D concentration measured ( Table 8 ).

However, the R-11 surfactant concentration was four times the acute endangered

species LOC for Delta smelt ( Table 9 ). Seeing an LOC exceedance for R-11 (a

nonylphenol containing surfactant) is not unexpected given that the R-11 LC50 for Delta

smelt is an order of magnitude lower than the 2,4-D Delta smelt LC50.

Table 8. Peak Concentration Risk Quotient Calculations for 2,4-D Application

Experimental

Concentration

Range Toxicity

Value Toxicity measurement,

regulatory tolerance,

action or guidance value Risk Quotient RQ exceeds LOC

or other regulatory

guideline?

27.5 μg/l 315 μg/l Chinook salmon LC50 0.087 No

7.2 mg/l D. magna LC50 0.0038 No

100 mg/l P. promelas LC50 0.000275 No

128 mg/l Delta smelt NOEC 0.000215 No

Table 9. Peak Concentration Risk Quotient Calculations for Surfactant (R-11) during 2,4-D

Application.

Experimental

Concentration

Range Toxicity

Value Toxicity measurement,

regulatory tolerance,

action or guidance value Risk Quotient RQ exceeds LOC

or other regulatory

guideline?

22.6 μg/l 5700 μg/l C. dubia LC50 0.004 No

420 μg/l C. dubia NOEC 0.05 No

1100 μg/l P. promelas LC50 0.02 No

340 μg/l P. promelas NOEC 0.06 No

700 μg/l Delta smelt LC50 0.03 No

100 μg/l Delta smelt NOEC 0.2 Yes (Acute

Endangered)

3900 μg/l Sacramento splittail LC50 0.006 No

1900 μg/l Sacramento splittail NOEC 0.01 No



# APMP research has indicated that 2,4-D alone and in combination with a

nonylphenol surfactant may cause endocrine disruption in juvenile O. mykiss at labelapproved application rates. Work is continuing to determine if 2,4-D itself is an

endocrine disruptor or if dichlorophenol (a primary 2,4-D breakdown product) is the

source of the vitellogenin induction.AquaticPesticideMonitoringProgramFinalReport26Table10.SedimentQualityTrendCalculationsfor2,4-D(DMA)SiteStation2,4-DporewaterrankAmphipodMeanLengthrankAmphipod%SurvivalrankToxicityRankNumberofChironomidaeGenerarankSpeciesRichnessrankStoneLakeSL2-010.49960.39096.25006.00509.6775StoneLakeSL2-020.0000.2510096.250542.0008.67100Pre-App0.511000.278588.7510010010.0010012.670Dataareanaverageofindividualreplicatesatpre-app(reference)vs.2wk(eachtreatedstation)Chemistry,toxicity,andbenthosarescaledproportionallybetween0(e.g.lowtoxicity)and100(e.g.hightoxicity)ToxicityandBenthos(speciesrichnessonly)arereverserankedtoreflectassumedrelationshiptometalapplicationThetoxicityrankisthecombinedrankingofbothmeanlengthandpercentsurvivalranksforHyalellaaztecaTable11.Summaryof2,4-D(DMA)SedimentQualityTrendDataChemistryToxicityBenthosStoneLake(2,4-D)2003PossibleConclusion+++Evidenceofpesticide-induceddegradation---SL201,SL202Noevidenceofpesticideinduceddegradation+--Pesticidesarenotbioavailable-+-Chemicalsotherthanpesticideorconditionsexistwithpotentialtocausedegradation--+Benthicresponsenotduetopesticide++-Pesticidemaybestressingthesystem-++Chemicalsotherthanpesticideorconditionsarecausingdegradation+-+PesticideisnotbioavailableorbenthicresponseisnotduetochemistryAplus(+)forchemistryindicatesametalconcentrationthatexceededeithertheporewaterLC50reportedforChironomusplumosusAplus(+)fortoxicityindicatesasignificantdecreaserelativetocontrolineitheramphipodgrowthorpercentsurvivalAplus(+)forbenthosindicateseitherachironomidgenerarichnessortotalspeciesrichnessvaluethatwassignificantlydifferentfromthereferencestations

# Aquatic Pesticide Monitoring Program

Final Report



# 27 Copper Sulfate

Copper sulfate was monitored in all three years of the project at four reservoirs in

Marin Municipal Water District (MMWD). Copper sulfate is applied to the Marin

reservoirs for floating and benthic algae control.

Two reservoirs received copper treatments (Nicasio and Bon Tempe Reservoirs)

and two untreated reservoirs were used at reference locations (Soulajule Reservoir and

Lake Lagunitas). Soulajule Reservoir was only sampled during year one. Nicasio and

Soulajule reservoirs are located in the West Marin watershed. Lake Lagunitas and Bon

Tempe reservoir are located in the Mount Tamalpais watershed. Nicasio Reservoir was

treated for floating algae with copper sulfate applied by dissolution of granular copper

sulfate through burlap bags towed with a boat. Bon Tempe Reservoir was treated with

granulated copper sulfate for benthic algae control. Granulated copper was applied with

a hopper mounted to the side of a boat. Soulajule Reservoir has never been treated with

copper and Lake Lagunitas has not been treated since the 1920s.

Tables 13 and 14 summarize the sediment quality triad measurements for the

copper sulphate applications in the MMWD. This analysis indicates that multiple

stations in Bon Tempe reservoir show evidence of copper induced degradation. The

impacted locations vary between years of data collected mostly likely due to the variation

of sediments within the samples areas. In Nicasio reservoir, while no sites exhibited

degradation of all three lines of data, three sites did show the potential for ecosystem

impacts.

Experimental concentrations and risk quotients are summarized in Tables 12

.

Table 12. Water Risk Quotient Calculations for Copper Sulfate Applications (Reservoir System)

Toxicity

Value Toxicity

measurement or

guidance value Risk Quotients

(Risk quotients in bold and underlined

indicate an LOC exceedance)

Peak

Concentration t+24 hour

conc. t+1 week

conc.

0.0653 mg/l 0.0381 mg/l 0.0076 mg/l

0.068 mg/l C. dubia EC50 0.96 0.56 0.11

0.03 mg/l Daphnid NOEC 2.18 1.27 0.25

0.8 mg/l Rainbow Trout

48hr LC50 0.08 0.048 0.0095

2300 mg/l Duckweed EC50 .00003 1.6E-5 3.3E-6

# Aquatic Pesticide Monitoring Program

Final Report



# 28 Water toxicity testing in Bon Tempe found acute water toxicity to O. mykiss and

acute and chronic toxicity to C. dubia shortly after copper application. Water toxicity

was found at all time intervals after application. Inhibition of C. dubia reproduction was

the primary toxicity detected, but the magnitude of toxicity did not always reflect the

measured copper concentrations in the water. The most significant reproductive and

mortality effects took place immediately after application. Significant trout mortality

occurred in one sample collected immediately after application. The 24 hour and one

week post application samples also inhibited reproduction of C. dubia although

concentrations did not exceed the copper LOEC for inhibition.AquaticPesticideMonitoringProgramFinalReport29Table13.SedimentQualityTrendCalculationsforCopperSulphateSiteStationCopperSedrankCopperporewaterrankAmphipodMeanLengthrankAmphipod%SurvivalrankToxicityRankNumberofChironomidaeGenerarankSpeciesRichnessrankBonTempeB-012390.00890.051000.087368.001001004.08337.3380BonTempeB-02733.67260.04790.132799.00012.0004.17100BonTempeB-032693.331000.05980.078982.5053792.83135.4292BonTempeB-04687.00240.01250.0610085.0045814.33377.4279BonTempeB-05935.67340.02330.105891.0026393.42225.9289BonTempeB-06474.00160.01100.141094.001604.834512.1749LagunitasL-0146.4300.0000.132790.0029218.3310019.750LagunitasL-0256.1300.0020.114592.0023284.834511.9250LagunitasL-0346.5000.0000.15082.0055207.508716.5820BonTempeB-01682.00550.0000.179795.336526.3308.8979BonTempeB-021200.001000.03550.1710081.601001007.33377.22100BonTempeB-03437.00340.0130.217994.5012458.67889.2275BonTempeB-04449.67350.0000.179685.0077866.67137.8992BonTempeB-05338.50260.02530.198887.0063767.333710.2263BonTempeB-06388.50300.0000.227595.505408.006310.7856LagunitasL-0140.6000.041000.37096.25009.0010015.330NicasioN-0599.651000.00340.188174.001001006.0006.5086NicasioN-0638.75150.00190.221093.501906.50209.1714NicasioN-0728.0500.011000.23081.5069268.501009.505NicasioN-1456.60400.00210.1610090.0033698.00809.670NicasioRefN-1159.2440.0000.212998.00007.00407.0073NicasioRefN-1352.90350.00100.195590.0033396.0006.00100Dataareanaverageofindividualreplicatesateachapplicationtime.Chemistry,toxicity,andbenthosarescaledproportionallybetween0(e.g.lowtoxicity)and100(e.g.hightoxicity).ToxicityandSpeciesrichnessarereverserankedtoreflectassumedrelationshiptotoxicity.ThetoxicityrankisthecombinedrankingofbothmeanlengthandpercentsurvivalranksforHyalellaazteca.AquaticPesticideMonitoringProgramFinalReport30Table14.SummaryofCopperSulphateSedimentQualityTrendDataChemistryToxicityBenthos2003Stations2004StationsPossibleConclusion+++B01,B02,B04B01,B02,B03,B04,B05Evidenceofcopper-induceddegradation---N07,N06,N14Noevidenceofcopperinduceddegradation+--B06Copperisnotbioavailable-+-N05Chemicalsotherthancopperorconditionsexistwithpotentialtocausedegradation--+Benthicresponsenotduetocopper++-B05Metalsmaybestressingthesystem-++Chemicalsotherthancopperorconditionsarecausingdegradation+-+B03B06CopperisnotbioavailableorbenthicresponseisnotduetochemistryAplus(+)forchemistryindicatesaconcentrationofCuthatexceededeithertheSedimentQualityGuidelineERLforCuorporewaterreportedinSuedeletal.1996.Aplus(+)fortoxicityindicatesasignificantdecreaserelativetocontrolineitheramphipodgrowthorpercentsurvival.Aplus(+)forbenthosindicateseitherachironomidgenerarichnessortotalspeciesrichnessvaluethatwassignificantlydifferentfromtheLagunitasreferencestations.

# Aquatic Pesticide Monitoring Program

Final Report



# 32 Chelated Copper

Chelated copper was monitored within the canal systems of Solano Irrigation

District (SID) and Potter Valley Irrigation District (PVID). The chelated copper is

applied to the ID canals for macrophyte and filamentous algae control. PVID applied

Cutrine Plus® which is a copper ethanolamine mixture. SID applied Clearigate® which

is a copper ethanolamine mixture in an emulsified formulation. Both products contain

unique unspecified ‘inert ingredients’ that may cause them to have different

environmental fates and toxicological properties. In the two irrigation district system

canals monitored, the copper treatments consisted of chelated copper pumped into the

canals as the water passed through a weir to aid in mixing. Each treatment lasted for a 2-

3 hours.

Tables 16 and 17 summarize the sediment quality triad measurements for the

chelated copper applications in Byrnes Canal. These measurements indicate that copper

induced degradation is occurring at one site and may be stressing the system at the other

site.

Water toxicity testing in conjunction with these applications showed intermittent

toxicity pre and post application. The peak water concentrations detected during the

three applications exceed the LOCs. Experimental concentrations and risk quotients are

summarized in Table 15

.

Table 15. Water Risk Quotient Calculations for Chelated Copper Applications (Irrigation Canal

Systems)

Toxicity

Value Toxicity

measurement or

guidance value Risk Quotients

(Risk quotients in bold and underlined

indicate an LOC exceedance)

Peak

Concentration t+4 hour

conc. t+11 hour

conc

1.43 mg/l 0.0988 mg/l 0.0988 mg/l

9.9 mg/l Water flea

Alonella LC50 0.144 0.01 0.002

0.0023mg/l Fathead Minnow

larvae 48hr LC50 621 43 7.39AquaticPesticideMonitoringProgramFinalReport33Table16.SedimentQualityTrendCalculationsforChelatedCopperSiteStationCopperSedrankCopperporewaterrankAmphipodMeanLengthrankAmphipod%SurvivalrankToxicityRankNumberofChironomidaeGenerarankSpeciesRichnessrankByrnesCanalBC-01609.001000.0100.176858.00325018.0010028.670ByrnesCanalBC-02211.0000.0110.1610035.001001008.00019.6752Pre-App565.50890.131000.20069.000011.003011.33100Dataareanaverageofindividualreplicatesatpre-app(referenceallstations)vs.2wk(pertreatedstation)Chemistry,toxicity,andbenthosarescaledproportionallybetween0(e.g.lowtoxicity)and100(e.g.hightoxicity)ToxicityandBenthos(speciesrichnessonly)arereverserankedtoreflectassumedrelationshiptometalapplicationThetoxicityrankisthecombinedrankingofbothmeanlengthandpercentsurvivalranksforHyalellaaztecaTable17.SummaryofChelatedCopperSedimentQualityTrendDataChemistryToxicityBenthosByrnesCanal2003PossibleConclusion+++BC01Evidenceofcopper-induceddegradation---Noevidenceofcopperinduceddegradation+--Copperisnotbioavailable-+-BC02Chemicalsotherthancopperorconditionsexistwithpotentialtocausedegradation--+Benthicresponsenotduetocopper++-Metalsmaybestressingthesystem-++Chemicalsotherthancopperorconditionsarecausingdegradation+-+CopperisnotbioavailableorbenthicresponseisnotduetochemistryAplus(+)forchemistryindicatesametalconcentrationthatexceededeithertheSedimentQualityGuidelineERLorporewaterLC50reportedforHyalellaaztecaAplus(+)fortoxicityindicatesasignificantdecreaserelativetocontrolineitheramphipodgrowthorpercentsurvivalAplus(+)forbenthosindicateseitherachironomidgenerarichnessortotalspeciesrichnessvaluethatwassignificantlydifferentfromthereferencestations

# Aquatic Pesticide Monitoring Program

Final Report



# 34 Diquat Dibromide

Diquat dibromide was sampled at two locations during the APMP. One location

was at a homeowners association property where diquat was applied to treat sago

pondweed by a local licensed pesticide applicator. The second location was in 7-Mile

Slough in the Sacramento/ San Joaquin Delta where diquat was applied by Department of

Boating and Waterways staff for control of Egeria densa

.

Water chemical characterization and toxicity testing were conducted during both

sampling events. Limited sediment monitoring was conducted because diquat adsorbs

irreversibly to sediment and once bound is no longer considered bioavailable.

At the Sand Bay site, diquat was found at 300 and 400 ppb immediately after

application. This concentration was double that of the highest concentration found at 7-

Mile Slough (195 ppb). Peak water diquat dibromide concentration risk quotients

exceeded LOCs at both applications. Interestingly, LOC exceedances were observed

preapplication at the Delta site. This is indicative of diquat runoff from upstream urban

and terrestrial applications. Experimental concentrations and risk quotients are

summarized for diquat in Table 18.

# Aquatic Pesticide Monitoring Program

Final Report



# 35 Table 18. Water Risk Quotient Calculations for Diquat Dibromide Applications

Toxicity

Value Toxicity

measurement or

guidance value Risk Quotients

(Risk quotients in bold and underlined indicate an LOC

exceedance)

preapplication conc. t+1 hour conc. t+24 hours conc.

7-Mile: 13.8 μg/l

Sand Bay: 0.79 μg/l 7-Mile: 180 μg/l

Sand Bay: 400 μg/l 7-Mile: 4.5 μg/l

19 μg/l S. capricornutum

. EC50 (growth) RQ 7

- Mile 

# =0.73

RQ Sand Bay 

# =0.04 RQ 7

- Mile 

# =9

RQ Sand Bay 

# =21 RQ 7

- Mile 

# =0.24

44 μg/l Algae NOEC

(biomass growth) RQ 7-Mile 

# =0.31

RQ S and Bay 

# =0.02 RQ 7

- Mile 

# =4

RQ Sand Bay 

# =9 RQ 7-Mile 

# =0.1

32 μg/l D. magna LC50 RQ 7

- Mile 

# =0.43

RQ Sand Bay 

# =0.025 RQ 7 -Mile 

# = 5.6

RQ Sand Bay 

# = 13 RQ 7

- Mile 

# =0.14

36 μg/l Daphnid NOEC RQ 7-Mile 

# =0.38

RQ Sand Bay 

# =0.02 RQ 7

- Mile 

# =5

RQ S and Bay 

# =11 RQ 7-Mile 

# =0.125

120 μg/l Minnow NOEC RQ 7-Mile 

# =0.115

RQ Sand Bay 

# =6E-3 RQ 7

- Mile 

# =1.5

RQ S and Bay 

# =3.3 RQ 7-Mile 

# =0.038

7600 μg/l P. promelas LC50 RQ 7-Mile 

# =0.0018

RQ Sand Bay 

# =1E-4 RQ 7-Mile 

# =0.02

RQ Sand Bay 

# =0.05 RQ 7-Mile 

# =6E-4

11 μg/l Duckweed LOEC RQ 7

- Mile 

# =1.25

RQ Sand Bay 

# =0.72 RQ 7

- Mile 

# =16

RQ Sand Bay 

# =36 RQ 7-Mile 

# =0.4

18 μg/l Duckweed EC50 RQ 7

- Mile 

# =0.76

RQ Sand Bay 

# =0.044 RQ 7

- Mile 

# =10

RQ Sand Bay 

# =22 RQ 7-Mile 

# =0.25

# Aquatic Pesticide Monitoring Program

Final Report



# 36 Fluridone

Fluridone (in the form of Sonar®)was monitored at multiple locations during the

three years of the APMP. In 2002, a liquid fluridone application was monitored in

Merced Irrigation District’s Main Canal and pelleted applications in Clear Lake. In 2003,

pelleted fluridone applications to Big Bear Lake, in the San Bernardino mountains, and

liquid fluridone applications to Costa Ponds, a fishing resort near Porterville California,

were monitored. In 2004, more extensive sediment analysis of Clear Lake was conducted

to investigate long term nontarget plant toxicity. Only at the Big Bear Lake and Costa

Pond applications were sufficient data collected to performed sediment quality triad

analysis. A Typha ssp seed germination and plant growth toxicity test was used for

samples collected from Big Bear Lake, Clear Lake, and Costa Ponds. In addition seed

germination rate, both the mean root and shoot growth are recorded as sublethal

endpoints.

Tables 20 and 21 summarize the sediment quality triad measurements for the

fluridone applications to Big Bear Lake and Costa Ponds. These measurements indicate

that fluridone induced degradation is occurring at three Costa Ponds sites and one Big

Bear Lake Site. At other sites, some lines of evidence indicate ecosystems impacts.

In 2004, multiple Clear Lake sediment and porewater samples were collected to

investigate the potential long term toxicity to nontarget plant organisms. Clear Lake

shore segments have been treated for different intervals over the preceding decade.

Samples were collected from sites that had not been treated for a varying number of

years. However, site conditions make it likely that fluridone containing sediment is

constantly transported through the lake making toxicity test results inconclusive.

Tissue samples (Sacramento suckers, crayfish, and rainbow trout) were collected

during the Merced Irrigation District eight week application of liquid fluridone in their

Main Canal. The data indicate that fluridone did accumulate in tissue during the

applications and persisted two weeks following application. At four weeks after the

cessation of treatment, tissue concentrations had returned to preapplication levels. No

LOC exceedances were observed with the MID applications ( Table 19 )

# Aquatic Pesticide Monitoring Program

Final Report



# 37 Table 19. Peak Risk Quotient Calculations for Fluridone Application at MID Main Canal

Toxicity

Value Toxicity

measurement or

guidance value Risk Quotients

(Risk quotients in bold and underlined indicate an LOC

exceedance)

Preapplication

concentration Mid Application Post Application

N on Detect 37 μg/l 102 μg/l

2.1 mg/l D. magna LC50 0 0.018 0.048

200 μg/l D. magna NOEC 0 0.185 0.51

6.2 mg/l P. promelas LC50 0 0.006 0.016

1.88 mg/l P. promelas NOEC 0 0.02 0.054

1.28 mg/l Delta smelt NOEC 0 0.029 0.08AquaticPesticideMonitoringProgramFinalReport38Table20SedimentQualityTrendCalculationsforFluridoneSiteStationFluridonePoreWaterrankTyphaMeanRootLengthrankTypha%GerminationrankToxicityRankNumberofChironomidaeGenerarankSpeciesRichnessrankCostaPondsCP-020.928010.403796.6567273.001005.7835CostaPondsCP-031.161009.2010098.900212.67677.000CostaPondsCP-040.847311.10095.55100212.33335.7835CostaPondsCP-051.038910.155095.551001002.0006.3319CostaPondsRefCP-010.0009.458798.90002.33333.56100BigBearBBP-010.1898.40100100.0001007.006711.0048BigBearBBP-020.28178.7090100.000884.00175.67100BigBearBBP-030.0809.7055100.000465.00338.0077BigBearBBE-010.997810.8017100.00004.00179.0068BigBearBBE-021.2410011.30097.801001003.00012.0039BigBearRefBBC-010.1789.3069100.000639.0010016.000DataareanaverageofindividualreplicatesateachapplicationtimeChemistry,toxicity,andbenthosarescaledproportionallybetween0(e.g.lowtoxicity)and100(e.g.hightoxicity)ToxicityandBenthos(speciesrichness)arereverserankedtoreflectassumedrelationshiptotoxicityThetoxicityrankisthecombinedrankingofbothmeanrootlengthandpercentgerminationforTyphalatifoliaTable21SummaryofFluridoneSedimentQualityTrendDataChemistryToxicityBenthosStationsPossibleConclusion+++BBP02,CP02,CP03,CP05Evidenceofpesticide-induceddegradation---Noevidenceofpesticideinduceddegradation+--BBE01,BBE02Pesticidesarenotbioavailable-+-BBP01,BBP03Chemicalsotherthanpesticideorconditionsexistwithpotentialtocausedegradation--+Benthicresponsenotduetopesticide++-Pesticidemaybestressingthesystem-++Chemicalsotherthanpesticideorconditionsarecausingdegradation+-+CP04PesticideisnotbioavailableorbenthicresponseisnotduetochemistryAplus(+)forchemistryindicatesametalconcentrationthatexceededtheporewaterEC50reportedforStonewortAplus(+)fortoxicityindicatesasignificantdecreaserelativetocontrolineitherplantgrowthorpercentgerminationAplus(+)forbenthosindicateseitherachironomidgenerarichnessortotalspeciesrichnessvaluethatwassignificantlydifferentfromthereferencestations

# Aquatic Pesticide Monitoring Program

Final Report



# 40 Glyphosate

Glyphosate was monitored at four locations during the APMP. There were three

canal sites; 1) Doris Drain, an agriculture return flow canal, near Ventura, 2) Merced

Irrigation District’s Atwater Canal, and 3) an Orange County Public Works Department

stormwater canal. Glyphosate applications were also monitored at Stone Lake National

Wildlife Refugee. All applications were made with a tank mix of glyphosate and

nonionic nonylphenolethoxylate surfactant. Triad monitoring was conducted only at

SLNWR.

Since glyphosate is considered to be biologically unavailable once it is sediment

bound, only limited sediment quality data was gathered and sediment quality triad

calculations were not performed. At all sampling sites, no acute or acute-restricted LOC

exceedances occurred. All the sites where glyphosate was applied were lotic systems

where chronic exposures could not have occurred.

The Doris Drain application showed the highest glyphosate water concentrations

(up to 1800 ppb immediately after treatment). No LOC exceedances for nontarget

organisms were observed. However several exceedances were observed for the R-11

surfactant applied in conjunction with the glyphosate ( Table 22 ).

Table 22. Risk Quotient Calculations for Surfactant (R-11) during Glyphosate Application at Doris

Drain.

Toxicity

Value Toxicity measurement or

guidance value Risk Quotients

(Risk quotients in bold and underlined

indicate an LOC exceedance)

preapplication

conc. t+0 hour

conc. t+3 hour

conc.

<RL μg/l 120 μg/l 19.6 μg/l

5700 μg/l C. dubia LC50 0 0.021 0.003

420 μg/l C. dubia NOEC 0 0.29 0.047

1100 μg/l P. promelas LC50 0 0.11 0.018

340 μg/l P. promelas NOEC 0 0.35 0.058

700 μg/l Delta smelt LC50 0 0.17 0.028

100 μg/l Delta smelt NOEC 0 1.2 0.196

3900 μg/l Sacramento splittail LC50 0 0.031 0.005

1900 μg/l Sacramento splittail NOEC 0 0.063 0.01

# Aquatic Pesticide Monitoring Program

Final Report



# 41 Methoprene

Methoprene was monitored in conjunction with an application made to a tidally

influenced wetland (Swanton’s Marsh) near the town of Martinez. The wetland is

situated between the Tesoro Corporation refinery and the Concord Naval Weapons

station. The wetland is fed from inland streams that also flow through methoprene

treated marshes upstream. Normally Swanton’s marsh is treated with a mixture of

methoprene and Bacillus thuringiensis israelensis, but for the benefit of this research the

Contra Costa Mosquito Vector control district modified their application routine and only

methoprene was applied.

This is the only site where an insecticide was monitored during the APMP.

Therefore, the methods used at this site differ significantly from those at the herbicide

monitoring locations. At this site, water, porewater, and sediment chemical

characterization, laboratory sediment toxicity testing, and in-situ sediment toxicity testing

were performed. The laboratory toxicity test used larval insect Chironomus tentans in

10-day survival and growth tests. The C. tentans are more sensitive to methoprene than

H. azteca

.

In addition, in-situ H. azteca toxicity tests were performed. The literature review

and conversations with mosquito vector control scientists indicated that methoprene had a

short window of bioavailability after application. To attempt to conduct a test within the

methoprene breakdown time frame, it was felt to be worthwhile to attempt in-situ

exposures. The test method was modified from the EPA standard H. azteca test

methodology by UC Davis Marine Pollution Studies Laboratory scientists.

Methoprene was not detected in any water samples collected from the site.

Methoprene is known to degrade quickly in water and sunlight. The day sampling

occurred no clouds were present and the temperature was over 100F.

# Aquatic Pesticide Monitoring Program

Final Report



# 42 Methoprene was detected in all sediment (including preapplication and reference

site) porewater samples. The concentrations ranged from 11.6-22.6 ppb. Methoprene was

found in the sediments at concentrations ranging from 178-2080 ppb. At the reference

site, the methoprene concentration was 178 ppb preapplication and 1800 ppb 4 days after

application. The reference site is highly influenced by tidal flow and receives sediment

from upstream locations. These upstream locations are treated with methoprene, but are

not immediately adjacent to the reference site. Peak water methoprene concentration risk

quotients did not exceeded LOCs. Experimental concentrations and risk quotients are

summarized in Table 23

.

Swanton’s marsh is treated with methoprene approximately twice a month. The

fact that methoprene was found pre-application indicates that it is persistent in the soil for

at least several weeks. USEPA methoprene reregistration documents state that

methoprene is persistent in the soil for up to 10 days, is tightly bound to soil, and is

degraded primarily by microbes (USEPA 1982).

Table 23. Peak Concentration Risk Quotient Calculations for Methoprene Application

Experimental

Concentration

Range Toxicity Value Toxicity measurement,

regulatory tolerance,

action or guidance value Risk Quotient RQ exceeds LOC

or other regulatory

guideline?

Porewater

22.6 μg/l 2 μg/l M. bahia LOEC 11.3 Yes

1250 μg/l H. azteca LC50 0.018 No



# The C. tentans toxicity test results were inconclusive. Significant mortality was

seen at the two treated sites pre-application and post application. Significant growth

reduction was seen in the samples collected at all three sites pre and post application.

Many of the sediments from this site were highly anoxic. It is likely that the anaerobic

nature of the sediments were the cause of the significant growth reductions and mortality

seen. Dissolved oxygen concentrations at the three sites averaged 3.6 mg/l. Total

ammonia concentrations ranged from 11.6-4.0 mg/l (average 8.54 mg/l). Total sulfide

ranged from 0.21-<0.01 (average 0.1 mg/l).

The in-situ H. azteca tests were also inconclusive. H. azteca were healthy at 96

hours, but the majority of test organisms were dead after 10 days. The test animals could

have died due to environmental conditions (anoxia) or lack of food in the 10-day

exposures.

# Aquatic Pesticide Monitoring Program

Final Report



# 43 The inconclusiveness of the two types of toxicity tests at this site highlight the

difficulty of conducting monitoring at such a site. Methoprene is applied to control larval

mosquitoes. The preferred habitat for the mosquito larvae is very shallow still waters.

Such a water environment often leads to anaerobic water and sediment.

Triclopyr

California Department of Food and Agriculture (CDFA) personnel applied

Renovate® triclopyr triethylamine salt at Bear Creek in 2003. A one percent triclopyr

and 0.5 percent Target Prospreader Activator (TPA), a surfactant, by volume solution

was applied to an approximately 0.34-acre creek section for the control of dense native

water primrose ( Ludwigia sp .). The herbicide tank mix was applied with a backpack

hand-pump sprayer to the surface of the floating vegetation mats. As triclopyr had only

recently received its aquatic use label, the number of applications made during the APMP

were very limited.

Although triclopyr is likely to partition to sediment, sediment was not collected at

this site because the creek bed was predominantly cobbles covered by a fine layer of silt.

The cobbles made it impossible to collect enough sediment for analysis with a sediment

sampler. The layer of silt present was too thin to gather enough sediment for analysis by

any other means. This lack of sediment data made it impossible to conduct sediment

quality triad analysis of the application.

Water chemistry results indicated that there were no triclopyr risk quotient LOC

exceedances. Water toxicity tests were inconclusive due to sampling error.

Nonylphenolethoxylate surfactant was found in the creek water both pre and post

application ( Table 24 ). Upstream sources could not be identified. The post application

samples showed continuous increases in concentration with the maximum value at 24

hours after application (2390 ppb). This peak could be due to additional upstream inputs,

or a dispersion pattern different from that of triclopyr. The surfactant risk quotients show

LOC exceedances pre and post application for a variety of aquatic animal species.

Table 24. Risk Quotient Calculations for Surfactant during Triclopyr Application.

Toxicity

Value Toxicity measurement or

guidance value Risk Quotients

(Risk quotients in bold and underlined indicate

an LOC exceedance)

preapplication t+0 hour t+2 hours t+24

# Aquatic Pesticide Monitoring Program

Final Report



# 44 conc. conc. conc. hours

conc.

5 70 μg/l Non Detect 185 μg/l 2390

μg/l

5700 μg/l C. dubia LC50 0.1 0 0.032 0.42

420 μg/l C. dubia NOEC 1.36 0 0.44 5.7

1100 μg/l P. promelas LC50 0.52 0 0.17 2.17

340 μg/l P. promelas NOEC 1.68 0 0.54 7.03

700 μg/l Delta smelt LC50 a 

# 0.81 0 0.26 3.41

100 μg/l Delta smelt NOEC a 

# 5.7 0 1.85 23.9

3900 μg/l Sacramento splittail LC50 a 

# 0.15 0 0.047 0.61

1900 μg/l Sacramento splittail NOEC a 

# 0.30 0 0.097 1.26

a

. 

# Delta smelt and Sacramento splittail toxicity data for R-11. TPA and R-11 have very similar chemical

and toxicity characteristics.



# CONCLUSIONS

Use of the limited data gathered during the three pesticide application seasons that

the APMP has existed should be limited to screening purposes only to identify where

further risk characterization or research may be needed. APMP generated chemical

characterization, toxicity, and bioassessment data. The chemical characterization and

toxicity data generated can be used for screening purposes. In complex field situations,

bioassessments require multiple years of data before even preliminary conclusions can be

drawn from them.

Specific conclusion concerning individual pesticides:

2,4-D

Only one application of 2,4-D (in the 2,4-D dimethylamine salt formulation) with

added surfactant was monitored. At this single application, no toxicity was observed nor

did risk quotients indicate the need for further information. Vitellogenin induction

laboratory experiments indicate that 2,4-D may cause endocrine disruption at legal

application rates.

The vitellogenin induction studies indicates the need for further study of the

aquatic 2,4-D formulations and their primary breakdown products. This level of research

should not be expected from entities conducting compliance monitoring.

Acrolein

# Aquatic Pesticide Monitoring Program

Final Report



# 45 Because of acrolein’s rapid volatilization, work focused on development of a field

sampling method that would allow for accurate determination of the pesticide in water.

Current standard environmental sampling methods are inadequate for sampling of

acrolein treated water and result in unbelievable analytical results.

Refinement of the sampling methodology began in 2003. Results indicate that the

method developed works well at low acrolein water concentrations. This refined method

makes it possible to determine acrolein residue values.

Due to acrolein’s rapid volatilization, it is currently not possible to conduct

standard water toxicity tests on it. Because of its’ extremely low Lowest Observable

Effect Concentration (LOEC) values, the detectable presence of acrolein indicates that

very high mortality to EPA water and sediment toxicity test species can be assumed.

The development of diagnostic response tests (i.e. phytomonitoring, sentinel

bivalves and fish, etc.) were explored and additional work is warranted. These tests have

the potential to provide a low cost, low tech method of detecting acrolein outside of

designated treatment areas.

Copper Sulfate

Copper sulfate applications were monitored in three reservoirs. In one reservoir

treatment area treated with dissolved copper sulfate, toxicity to juvenile trout and

Ceriodaphnia immediately after and, in some cases, up to a week following application.

Peak concentration risk quotients showed acute and chronic U.S. EPA Office Pesticide

Programs Levels-of-Concern (LOC) exceedances. At 24 hours post application the risk

quotients showed acute and chronic LOC exceedances. At one week post application the

risk quotients showed acute LOC exceedances.

In the reservoir treated with granular copper sulfate applications, significant

mortality was observed in Ceriodaphnia and juvenile trout water toxicity tests

immediately after application within the treatment area. Mortality and growth inhibition

was also observed in a number of the sediment samples. Sediment copper concentrations

at many sites exceeded a published Hyallela LC50 value. However, the toxicity observed

in the sediments indicates that the majority of the copper is not bioavailable.

# Aquatic Pesticide Monitoring Program

Final Report



# 46 These findings indicate the need for further risk characterization associated with

copper sulfate applications.

Chelated Copper

Chelated copper pesticides were monitored during applications in two irrigation

canal systems. One system used a product of mixed copper ethanolamines and the other

the same product of mixed copper ethanolamines in an emulsified formulation. Chelated

copper formulations are likely to have distinct behavior from copper sulfate and each

other in aquatic environments based on the chelating agent and other adjuvants. It should

be noted that copper carbonate is the active ingredient in other chelated copper products

and no monitoring of copper carbonate based pesticides was conducted.

In both systems where monitoring occurred, the water samples were almost

uniformly toxic preapplication and post application. Therefore, no definitive conclusions

can be drawn about the toxicity of mixed copper ethanolamines. The sediment quality

triad calculations indicate the possibility of copper impacts to the system.

Further risk characterization associated with chelated copper applications is

warranted.

Glyphosate

Glyphosate was monitored at several locations. No toxicity was found to be

associated with glyphosate applications. Glyphosate is very often applied with a

surfactant which may have much higher toxicity than the active ingredient.

Based on risk quotient calculations and toxicity data, no further risk

characterization associated with glyphosate applications alone is warranted. Risk

characterizations are warranted when a surfactant used in conjunction with the

glyphosate.

Diquat Dibromide

Diquat dibromide was sampled at two locations, one small pond and a delta

slough. Diquat risk quotients almost uniformly exceeded Levels of Concern at all

sampling periods in the Delta slough (including preapplication) and at one hour after

application in the pond. Diquat may be applied with a surfactant which may have much

# Aquatic Pesticide Monitoring Program

Final Report



# 47 higher toxicity than the active ingredient. Diquat sediment concentrations were not

considered as diquat is irreversibly adsorbed to sediments and thereafter not bioavailable.

Toxicity test and risk quotient results indicate the need for further risk

characterization.

Fluridone

Fluridone (applied in pellet or liquid form) was not found to be definitively toxic

to or have LOC exceedances for the USEPA three species water or sediment amphipod

organisms. The peak concentration risk quotient for Stonewort did exceed an Acute

LOC. Fluridone was found to cause sublethal toxicity (decreased shoot and root length)

to Typha. This would indicate a potential for impacts on nontarget plants.

Further risk characterization of fluridone impacts on nontarget plants is

warranted. There is also cause for concern over development of genetic resistance to

fluridone which is emerging in plant populations in Florida.

Methoprene :

Monitoring for methoprene is challenging because it is commonly applied to

environments that do not lend themselves to traditional water and sediment sampling and

testing methods (i.e. extremely shallow water and highly anoxic sediments). In situ and

laboratory toxicity tests were completed, but the results were inconclusive. From the one

site monitored for methoprene, water and porewater risk quotients indicate no need for

further risk characterization. Methoprene was persistent in marsh sediments, up to the

ppm level, for several weeks. Little methoprene sediment toxicity data could be located.

Future work is warranted to further characterize the risk of methoprene in

sediments. Additional studies may also be warranted due to the common simultaneous

application of methoprene and Bti.

Triclopyr

Triclopyr was monitored at one application only. Triclopyr peak concentration

risk quotients show no LOC exceedances. Triclopyr is often applied with a surfactant

which may have much higher toxicity than the active ingredient.

# Aquatic Pesticide Monitoring Program

Final Report



# 48 Limited further triclopyr risk characterization is warranted. Risk characterizations

are warranted when a surfactant is used with triclopyr.

Nonionic surfactants

The most commonly used surfactants at APMP monitoring sites were Target

Prospreader Activator and R-11. Both are nonylphenolethoxylate based surfactants.

Peak concentration risk quotients indicate exceedances of LOCs for a wide range of

animal species including Delta Smelt and Sacramento Splittail. Vitellogenin induction

experiments in Rainbow trout indicate that these nonylphenol surfactants can be an

endocrine disruptor at application rates. There are a wide range of surfactants available,

each one having a different toxicological profile. Due to their classification as an

adjuvant, very little data is required for registration. Risk characterizations are warranted

on all surfactants.



# MANAGEMENT AND ASSESSMENT QUESTIONS REVISITED

The Management and Assessment questions developed at the beginning of the project

were referred to throughout the planning and implementation of the APMP. Below is the

analysis of how well the APMP addressed each Management question.

1. Which aquatic pesticides used in California have the highest “risk” of impacts to

people and the environment? The literature review and field monitoring activities

have answered this question.

2. What are the concentrations of the target aquatic pesticides in the environment

(water, sediment, and biota) adjacent to their application point? The field

monitoring activities have begun to answer this question for the aquatic pesticides

of interest.

3. Are the measured concentrations above existing effects thresholds? This question

has been answered for the sites studied by comparison of collected field data with

published effects thresholds.

4. Which locations have the highest “risk” of beneficial use impairment? This

question was not specifically addressed as it was a sufficient challenge to find

# Aquatic Pesticide Monitoring Program

Final Report



# 49 sites suitable for monitoring that met the other selection criteria. Bioassessment

data indicates that all locations samples may be considered degraded.

5. What is the degree of biological impacts to non-target biota from application and

exposure to aquatic pesticides? The bioassessment and special toxicity tests

performed addressed this question.

6. What Best Management Practices are currently being used to mitigate potential

impacts from aquatic pesticide application? Pesticide application BMPs were not

evaluated as part of this project. Non-chemical pest control alternatives have been

studied extensively.

# Aquatic Pesticide Monitoring Program

Final Report



# 50 

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Canfield, T.J., Kemble, N.E., Brumbaugh, W.G., Dwyer, F.J., Ingersoll, C.G., and

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