### Exploring Approaches to Pesticide Aquatic



### Ecological Exposure Assessment: Issues in Evaluating Risk Across 

### the National Landscape Exposure Modeling Public Meeting September 20, 2011 

### Ronald Parker, Ph.D.

### Mission of EPA Office of Pesticide Programs



# • Protect Human Health and the Environment from Unreasonable Adverse Effects from the Use of 

# Pesticides

## Key Federal Pesticide Laws:



## FIFRA and FFDCA • Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)  Review and Register New / Older Pesticides  Risk / Benefit Balancing 

### • Federal Food, Drug, and Cosmetic Act (FFDCA)
 Establishes Tolerances (Maximum Residue Limits) for Pesticides on Food and Feed  Tolerances Apply to Domestic and Imported Foods  Monitoring for Tolerances Falls to FDA

## Key Federal Pesticide Laws: 

## FQPA
• Food Quality Protection Act of 1996  Amended FIFRA and FFDCA  Reassess All Tolerances Within 10 Years  The Agency Must Complete the Registration Review of Each New Pesticide Active Ingredient within 15 Years of its Initial Registration  Aggregate Exposures from Diet, Drinking Water , Residential and other Non -occupational Sources  Cumulative Effects and “Common Mechanism of Toxicity” e.g. Organophosphates  Current Registration Review Program Is Replacing EPA's Pesticide Reregistration and Tolerance Reassessment Programs  Operates Continuously, Encompassing All Registered Pesticides

## Key Federal Pesticide Laws:



# Endangered Species Act
• ESA Passed in 1973 and Amended in ’78’, ’82’, & ’88’ 

### • Section 7(a)(2) of the ESA Requires Federal Agencies (“Action Agencies”) in Consultation with the Services to Ensure that Any Action They Authorize, Fund or Carry Out Is Not 

### Likely to Jeopardize the Continued Existence of a Listed Species or Result in Destruction or Adverse Modification of Habitat Designated by the Services as Critical  Prohibits Against “Harming, Harassing, Pursuing, Hunting, Shooting, Wounding, Killing, Trapping, Capturing and Collecting any Listed Threatened or Endangered Species”

## Delineating the Scope of US



# Aquatic Landscape • Habitat: Extensive & Complex US Aquatic Landscape • 9,000,000 Ponds (Renwick, et al., 2005) • 3,660,000 Miles of Rivers, Streams and Canals (USEPA) • Perennial: 1,300,000 Miles • Non - perennial: 1,600,000 Miles • Canals & Ditches: 110,000 Miles • 123,439 Lakes > 10 Acres (USEPA) • 82,642 Reservoirs (National Inventory of Dams) • 102 Estuaries (USEPA) • Extensive & Complex Community Water System (CWS) Network • 11,671 Surface Water CWS Serve 204.1 Million People (USEPA) • 40,301 Ground Water CWS Serve 88.1 Million People (USEPA) • Extensive & Complex Agricultural Landscape • 2,080,000 Working Farms (USDA) • Extensive & Complex Urban Landscape • 19,000+ Municipal Governments • 275 Cities Over 100,000 Population

## Spatial Aquatic Model (SAM) Pilot Project

• “Proof of Concept” Pilot SAM Project Began in May • Scope of SAM Project • Developing Geographic Components for Spatial Modeling • Updating PRZM Routines and Links to Geographic Components • Take Advantage of Storage Capacity for Spatial Model Inputs and Outputs – “Super Scenarios” • Automate Linear Routing from Soil Map Units to Water • Test Run the Linked Models • Produce a Prototype Demonstration Model • Develop Recommendations for Production Model

## Purpose of New OPP Aquatic



# Exposure Modeling

• Ecological Risk Assessment (ERA) Is a Process that Evaluates the Likelihood that Adverse Ecological Effects May Occur or Are Occurring as a Result of Exposure to One or More Pesticides • Pesticide Aquatic Exposure Assessment Provides the Exposure Component of the Risk Assessment Equation • Main Purpose of Pesticide Risk Assessment Is to Inform Risk Management Decisions • Needs of Risk Managers Are the Main Motivation behind New Spatial Aquatic Modeling Project9 

## Current OPP Modeling Configuration 

# for Ecological Exposure Assessment: • Agricultural Field Scale • Field Area (10 ha) • 100% Treated • Pesticide Carried Off the Field by: • Runoff Water • Eroding Soil • Spray Drift • Adjacent Pond • Static (No Inflow or Outflow of Surface Water or Groundwater) • Site Specific Soil and Weather • Fixed Water Quality - Georgia Farm Pond • Pond Surface Area (1 Hectare) • Pond Depth (2 Meters) • Pond Volume (20x10 6 L iters) 10 ha (25 Acre ) Field 100% Pesticide Treated

1 ha (2.5 Acre) x 2 m Pond10

## Current EFED Field / Pond Configuration:

Empirically Also Serves as Conservative Screen for Rivers and Streams Receiving Runoff from Multiple Agricultural Fields11 

## Current Aquatic Screening Approach

Characterize Certainties and Uncertainties Management Decisions Based on One (or a Few) Conservative “Standard” Scenarios for Each Treated Crop12



## Advantages / Disadvantages of 

# Current OPP Modeling Configuration: • Advantages: • Easy to Describe and Understand • Valid for Comparisons among Pesticides • Provides Estimates of Temporal (Day-to- Day, Year-to-Year) Variability • All Applied Pesticide Retained within the Assessment System • Disadvantages: • This Combination of Land -Water Configuration and Site Assumptions Actually Exists Only Rarely • Does Not “Explicitly” Represent Flowing Water or Estuaries • Cannot Locate High - exposure “Hot-spots” for Mitigation 25 Acre (10 ha) Field 100% Pesticide Treated 2.5 Acre (1ha) x 2 m Pond13 

## Potential Transition to Spatially



# Explicit Assessment Current Aquatic Screening Process14 Soils, Hydrology, Elevation, Drainage Patterns, Weather, Land Use, Crop and Management Practices, Growing Season Spatial Representation of Pesticide Concentrations Across the Pesticide Use Area Gather Spatial Data Develop/ Adapt Models Determine Outputs Hydrology, Pesticide Fate and Transport Arrows Represent Key Model Linkages that Allow Us to Process Data and Models Spatially 

## Spatial Aquatic Modeling

## Conceptual Aquatic Exposure Model

Watershed With Pesticide Applications (PRZM) Receiving Water Body (EXAMS) Pesticide Fate and Transport Pesticide Loading

Soil, Site , Crop, Hydrology Weather (Rainfall, Temp., Irrigation) Registrant

Studies Fate/ Transport Properties

Use area Site- Specific Conditions App. Rates, Frequency, Timing Labels Runoff Spray Drift Soil Erosion Comparison with Toxicity Endpoints

- Aquatic Organisms

- Human Health Aquatic Exposures

- Concentration

- Duration

- Frequency

## “Super Scenario” Development Use GIS Coverages for Soil, Catchment Hydrology, Slope, Crops and Land Use

## PRZM Modeling Units and NHDplus



## Framework

NHDplus Catchments • Initial modeling will be aggregated within NHD+ catchments (shown as red lines) • Catchments are linked to stream reaches for hydrologic routing, processing NHDplus Hydrology • Hydrologic framework • Each stream reach (dark blue lines) serves as the “water body” • Downstream routing and/ or dilution follows NHD+ reaches SSURGO Soil Map Units • Soil mapping units (shown in various color tones) within each NHD+ catchment will serve as the basic PRZM modeling unit • Model inputs, outputs will be aggregated at the map unit scale A1 A2 A3

A4

A5 B1 B2 B3 B4 A1 – Basic Model Unit (soil map unit x catchment)

### Moving Outputs from Soil Map Units



### to the Stream Reach

• Once PRZM Pesticide Loads Arrive at the Stream Reach, NHD+ Can Be Used to Move them into Downstream Reaches to Drinking Water Intake Locations or into Drinking Water Reservoirs • One Challenge Is Moving the Outputs from Irregular Soil Mapping Units in the Catchment to Downslope Stream Reaches and then Estimating Downstream Dilution • We Have Been Looking to See How other Modelers Have Handled that Problem • Checked SWAT, BASINS, AGNPS, Recent University Publications and Industry Watershed Modeling • Focused on Using NHD+ Flow Grid Network 18

## Super PRZM Development

• Following Agency Guidance Regarding Data Quality and Best Practices for Model Development • Take Advantage of Modern Programming & Hardware • Using Parallel Processing, Reducing Redundancies, Storing Calculations for Later Use • Current PRZM: Hydrology, Crops, and Chemistry Are Largely Separate and Occur in Overlapping Loops • Super PRZM: Chemistry and Application Are Completely Separate from Hydrology, Crops, Soil and Weather • Hydrology/Crop Pre- calculations Are the Super Scenarios • Super Scenarios Are Stored in Unformatted Binary Form for Extra-fast Input / Output Performance 19

# Addressing Data Quality Issues

• Each PRZM Routine Was Reviewed for: • Availability of Science References • Application of Sound Science • Code Verification • Coding Inefficiencies • Coding Duplications • Issues Still Under Discussion • Spatial Extent of “Super- Scenarios” • Acceptable Levels of Simplification • Extent, Spatial and Temporal Variability of Application within Each Catchment • Addressing Temporal Variability of “Hot-spots”

## Displaying Outputs: Catchment Option Summarize Results at the NHD+ Catchment Scale • Map Shows the Results of AreaWeighting Averages by Catchment (No Downstream Flow) • Would Incorporate Simple Downstream Flow Routing to Account for Contributions from Upstream Areas22



## Displaying Outputs - Option 2: 

## Integrating Downstream Exposure

The Ideal Situation: Aquatic Exposure Estimates by Catchment (Left) Would Be Integrated Downstream with Information on Species Habitat (Above). This Approach Would Allow for Temporal Considerations

### Continuous Interaction with Risk Managers



### and Other End Users

• Main Purpose of Pesticide Risk Assessment Is to Inform Risk Management Decisions • Risk Managers Will Be Involved throughout the Model Development Process to Assure Optimal Usefulness of the Model in Guiding Risk Management Decision • Consultations Will Be Conducted through Questionnaires and Frequent Face-to- Face Meetings • Types of Decisions Needed Include: • Optimal Representation of Spatial and Temporal Model Outputs • Ancillary Data for Output Values • Characterization and Immediate Causes of “Hotspot” Occurances • Estimating Uncertainties 23

### Types of Questions for Risk Managers &



### Other End Users (1)

• Optimal Numbers and Locations of Output Concentration Values; Use of Temporal Ranges, Aerial Percentages, etc. • Most Useful Presentations of Output (Tabular, Maps, other) • Spatial Scale of Concentration Values of Most Use in Risk Management (Field, County, State, other) • Characterization of High Exposure Locations • Differences In Number and Sizes of Treated Fields and Receiving Water Bodies • Impact of Land to Water Ratios on Results • Impact of Flow on Results • Necessary Level of Validation (Comparison with Monitored Values) • Acceptable Levels of Uncertainty 24

### Types of Questions for Risk Managers &



### Other End Users (2)

• When Should Averaging, if Necessary, Occur? • How Much and What Types of Simplifications Are Acceptable? • What Types of Risk Mitigation (Exposure Reduction) Options Can Be Accurately Modeled • On -site Options for Runoff Reduction by Reduced Tillage, Incorporation, Grassed Buffers, etc., • On -site Options for Spray Drift Reduction by Separation Buffers • Use of Flow Reduction Buffers • Impact of Application Methods, Rates, Timings, Number, Intervals, Equipment, etc. 25

# Status as of 9/20

• Conceptual Model Framework Has Been Built • Spatial Framework Still under Development • Basic Modeling Units & Flow Routing Concept Established • Data Development for “Super Scenarios” Underway • Developing Programming for Scenario Development 

### • Super PRZM Has Been Compiled • Separate Hydrology and Pesticide Models Established • Awaiting Testing for Spatial Linkages 

### • Considering Options for Processing & Displaying Outputs • Scales for Drinking Water and Ecological Assessments • Developing Questions for Risk Managers & End Users 26