Spray Drift Expos

Spray Drift Expos

Refinements for Refinements for Sal

Sal

Off

-Channel Hab

Channel Hab

Nick Poletika, Dow Nick Poletika, Dow AgroSciences AgroSciences L

Rick Reiss, Exponent, Inc. Rick Reiss, Exponent, Inc.

Steve Cryer, DowAgroSciences DowAgroSciences LL

Steve Cramer, Cramer Fish Scienc

Steve Cramer, Cramer Fish Scienc

27 July 2010 EMPM Meeting 27 July 2010 EMPM Meeting
Background Background

3⁄4 Pesticide exposure from spray drift depos

Pesticide exposure from spray drift depos

salmonid salmonid off-channel habitat was identifie

channel habitat was identifie

concern in the 18 Nov 2008 National Mar

concern in the 18 Nov 2008 National Mar

Service (NMFS) ESA Section 7 consultat

Service (NMFS) ESA Section 7 consultat

opinion opinion

3⁄4 NMFS modeled off NMFS modeled off-channel exposure wit

channel exposure wit

2.0.05 Aquatic Assessment Tool, static U

2.0.05 Aquatic Assessment Tool, static U

Water Body with 10 Water Body with 10-m width and 0.1 m width and 0.1-m d

m d

3⁄4 Two questions related to this exposure m

Two questions related to this exposure m

emerged emerged

z Nature of off Nature of off-channel habitat and related scen

channel habitat and related scen

z Appropriate transport and fate models? Appropriate transport and fate models?
Range of Off-Channel H

Types

3⁄4 Examples given in NMFS Examples given in NMFS biop

z Alcoves, channel edge sloughs, 

Alcoves, channel edge sloughs, 

channels, backwaters, terrace tri

channels, backwaters, terrace tr

channel dredge ponds, and braid

channel dredge ponds, and braid

3⁄4 For definition of exposure scen

For definition of exposure scen

associated with agricultural lan

associated with agricultural lan

it necessary to include all exam

it necessary to include all exam
Representative Data: Stream in Oregon with Stream Survey 

Agricultural Use

Source: http://oregonstate.edu/dept/ODFW/freshwater/inventory/index.h
Primary Channel, Secondary 

and Off-Channel Areas 

3⁄4 Secondary (side) channels with flow 

considered “off-channel”

3⁄4 Note that secondary channel area >

channel” area

River Basin Primary Channel Secondary 

Channel 

Secondary 

Channel Area 

(%) 

O

Coquille 303,729 5,808 1.88 Hood 424,232 14,876 3.39 Rogue 675,047 29,843 4.23 Umpqua 1,334,737 38,877 2.83 Willamette 157,711 2,404 1.50 Total 2,895,456 91,808 3.07 
Off-Channel Habitat Data 

Adjacent to Agricultural 

3⁄4 Possible habitat units: alcove, back

isolated pool

3⁄4 Shade averages suggest presence 

spray drift interception zone is com

 Length (m) Width (m) Area (m

Habitat 

Unita

No. Mean Min Max Mean Min Max Mean Min 

Alcove 47 10.82 1.50 101.10 2.25 0.60 8.50 22.38 1.20 Backwater Pool 

147 10.06 1.00 85.20 2.95 0.50 13.00 36.11 0.90 

Isolated Pool 

101 9.74 0.00 117.10 3.02 0.30 42.50 63.74 0.00 

All 295 10.08 0.00 85.20 2.86 0.30 42.50 43.29 0.00 a River basins: Coquille, Hood, Rogue, Umpqua, and Willamette. Note: not all units ar
Salmonid Preference for Off

Habitat Found in Agricultur

3⁄4 Stream

-dwelling salmon and steelh

dwelling salmon and steelh

strongly adapted to coldwater envir

strongly adapted to coldwater envir

(<20

°C) and to feeding on organism

C) and to feeding on organism

the current the current

z Make use of side (secondary) channe

Make use of side (secondary) channe

from predators from predators

3⁄4 Will also use calm water habitats fo

Will also use calm water habitats fo

such factors as high velocity and hi

such factors as high velocity and hi

temperature temperature

z Alcoves and backwaters preferred Alcoves and backwaters preferredz Isolated pools less favorable for migra

Isolated pools less favorable for migra

and may have reduced water quality and may have reduced water quality 
Off-Channel Feature

Channel Feature

Importance in Agricultura

Importance in Agricultura

3⁄4 Three basic types, all with connecti

Three basic types, all with connecti

main channel main channel

z Side channels Side channels

• Flowing water bodies with clearly identifiab

Flowing water bodies with clearly identifiab

downstream connections downstream connections to the main chan

to the main chan

z Alcoves Alcoves

• Water bodies that maintain a downstream 

Water bodies that maintain a downstream 

main channel at summer low flow, but hav

main channel at summer low flow, but hav

connection during low flow connection during low flow

z Backwater pools Backwater pools

• A pool formed in free A pool formed in free-flowing streams by a

flowing streams by a

channel margins downstream channel margins downstream from obstruc

from obstru

bars, rootwads rootwads, or boulders , or boulders
Source: http://www.fsl.orst.edu/pnwerc/wrb/Atlas_web_compressed/3.Water_Resour

Willamette

River

Main

Examples of Side Chann

Examples of Side Chann

Alcoves Alcoves

Alcove

Alcove

Side Channel
Hyporheic Hyporheic Flow is Impo

Flow is Impo

Alcoves Alcoves

Source: http://www.fsl.orst.edu/pnwerc/wrb/Atlas_web_compressed/3.Water_Resour
Example of Backwate

Example of Backwate

Mokelumne River, CA

Hwy 99

Bar
Mass Exchange Occurs Betw

Mass Exchange Occurs Betw

Channel and Backwater 

Channel and Backwater 

Source: CA Dep. Fish and Game. 1998. California Salmonid Stream Habitat Restoratio

Boulder Formed

Root Wad 
Exposure Profile Exposure Profile

3⁄4 Characteristics of the three types of off Characteristics of the three types of off

-c

c

indicate flowing water is generally involve

indicate flowing water is generally involve

z Side channel Side channel 

– channel channel flow

z Alcoves Alcoves 

– hyporheic hyporheic flow + mixing with main c

flow + mixing with main c

z Backwater p Backwater pools 

– eddy current mass exchan

eddy current mass exchan

3⁄4 Time

-weighted average (TWA) concentra

weighted average (TWA) concentra

with exposure periods in acute toxicity tes

with exposure periods in acute toxicity te

best describe exposure conditions best describe exposure conditions

3⁄4 Can normalize exposure periods using Can normalize exposure periods using G

reciprocity relationship ( reciprocity relationship (Giesy et al., 1999

et al., 1999

3⁄4 Toxicokinetic Toxicokinetic modeling approach also po

modeling approach also po
Spray Drift Modeling A

Spray Drift Modeling A

3⁄4 Modeling methodology used to gen

Modeling methodology used to gen

concentration estimates for each ty

concentration estimates for each ty

channel habitat channel habitat

z Side Channels Side Channels

• Stream Assessment Tool (SAT) in Stream Assessment Tool (SAT) in AgDRIF

AgDRI

z Alcoves Alcoves

• Predict initial deposition with Predict initial deposition with AgDRIFT AgDRIFT 2.0

2.0

Assessment Tool and use dye study meas

Assessment Tool and use dye study meas

estimate change in concentration over tim

estimate change in concentration over tim

z Backwater Pools Backwater Pools

• Predict initial deposition with Predict initial deposition with AgDRIFT AgDRIFT 2.0

2.0

Assessment Tool and use channel flow da

Assessment Tool and use channel flow da

computational fluid dynamic modeling to e

computational fluid dynamic modeling to e

concentration over time concentration over time
Evaluation of Data Sour

Evaluation of Data Sou

Characterizing Off Characterizing Off

-Chann

Chann

3⁄4 Criteria Criteria

z Representative of agricultural are

Representative of agricultural are

z Provide reliable measurement da

Provide reliable measurement da

inputs

• Geometry Geometry• Flow

z Side channel current Side channel currentz Alcove dye study Alcove dye studyz Main channels (for flui Main channels (for fluid dynamic mode

d dynamic mode

exchange with backwater pools) exchange with backwater pools)
Representativeness for Ag

Representativeness for Ag

Areas 

- Method

3⁄4 Mapped off Mapped off

-channel habitat loc

channel habitat loc

relation to NLCD 2001 land cov

relation to NLCD 2001 land cov

z 11 Open Water 11 Open Waterz 81 Pasture/Hay 81 Pasture/Hayz 82 Cultivated Crops 82 Cultivated Crops

3⁄4 Locations confirmed as represe

Locations confirmed as represe

z Willamette River, OR. Willamette River, OR. Bryenton Bryenton z Mokelumne Mokelumne River, CA. Joe River, CA. Joe Merz

Sciences, personal communicati

Sciences, personal communicati
Willamette River Alc

Willamette River Alc
Mokelumne Mokelumne River Off River Off-Chan

Chan

and Side Channels and Side Channels
Side Channels Side Channels 

– Estim

Estim

Methodology Methodology

3⁄4 SAT runs with numerical integration 

time/concentration curve at each diExport file
Inputs for SAT: Relationship 

Inputs for SAT: Relationship 

with Depth in with Depth in Mokelumne Mokelumne R

R

Channels* Channels*

Range of interest for modeling

* 133 measurements on two s * 133 measurements on two side channels, J. ide channels, J. Merz, personal communication
Inputs for SAT: Distribution 

Inputs for SAT: Distribution 

Velocities in Velocities in Mokelumne Mokelumne R

R

Channels Channels

0

20406080

100

0 0.5 1 1.5 

Percentile

Mean Velocity (ft/se

= value use
Inputs for SAT: Distribution o

Inputs for SAT: Distribution o

Mokelumne Mokelumne River Side Ch

River Side Ch

= values use

NMFSvalue
Inputs for SAT Inputs for SAT 

– Side C

Side C

3⁄4 Velocity and dimensions characteri

Velocity and dimensions characteri

Mokelumne Mokelumne River data River data 

z Lower 10 Lower 10th percentile velocity: 0.07 ft/s

percentile velocity: 0.07 ft/s

z Depths: 4 inches, 1 foot, and 2 feet Depths: 4 inches, 1 foot, and 2 feetz Width: 10 meters, as per NMFS (insen

Width: 10 meters, as per NMFS (insen

parameter) parameter)

3⁄4 Riparian interception factor: 0.2 (OR 

Riparian interception factor: 0.2 (O

survey shade data) survey shade data)
Alcoves Alcoves – Estimation Met

Estimation Met

3⁄4 Calculate initial concentration i

Calculate initial concentration i

using AgDRIFT AgDRIFT Aquatic Assess

Aquatic Asses

z User-defined water body determ

defined water body determ

measured alcove dimensions measured alcove dimensions

3⁄4 Estimate time Estimate time-weighted concen

weighted concen

assuming an exponential declin

assuming an exponential declin

z Modeled with residence time me

Modeled with residence time me

taken using trace dyes taken using trace dyes
Key Data for Alcoves in W

Key Data for Alcoves in W

River

Alcove Width (feet) Width (feet) Depth 

(feet)

Harrisburg Bar

63.0 0.65

Green Island

75.4 2.0 

Norwood Slough

159.7 3.6 
Backwaters Backwaters 

– Estima

Estima

Methodology Methodology

3⁄4 Model flow in backwaters using 2 Model flow in backwaters using 2

-D 

computational fluid dynamics (FLU

computational fluid dynamics (FLU

z

2

-D used because depth term contribu

D used because depth term contribu

momentum equation relative to river w

momentum equation relative to river w

z Normalized concentration Normalized concentration

-time relation

time relatio

from measured channel velocity and p

from measured channel velocity and p

3⁄4 Determine initial concentration in po

Determine initial concentration in p

AgDRIFT AgDRIFT Aquatic Assessment Too

Aquatic Assessment Too

defined water body defined water body 

3⁄4 Apply concentration Apply concentration

-time curve to i

time curve to i

concentration to calculate time concentration to calculate time

-weig

wei

concentration in pool concentration in pool
Backwaters Backwaters – Estima

Estima

Methodology Methodology

3⁄4 Modeling based on flow data fr

Modeling based on flow data fr

Mokelumne Mokelumne River ( River (Pasternack Pasternack 

z Measurements made during a lo

Measurements made during a lo

“representative of salmon spawn

representative of salmon spawn

conditions conditions”

z Velocity measurements in main r

Velocity measurements in main 

up to 4.6 ft/sec with a median of up to 4.6 ft/sec with a median of approximately 1.6 ft/sec approximately 1.6 ft/sec

z Runs were made at 0.8 and 1.6 f

Runs were made at 0.8 and 1.6 

in main stem of river in main stem of river
Characteristics of Back

Characteristics of Back

Backwater Pool Backwater Pool Width (feet) Width (feet) 

AIB 120 Highway 99 75 AMBW #1 30 AMBW #2 45 

* Pasternak et al., 2003. * Pasternak et al., 2003.
CFD Flow Predictions for 

CFD Flow Predictions for 

99 Site 99 Site

m s-1
General Inputs General Inputs

3⁄4 Application rate of 1 lb Application rate of 1 lb a.i./A3⁄4 Droplet sizes Droplet sizes

z Aerial

• NMFS: Fine NMFS: Fine

-to

-medium

• Registrants: medium Registrants: medium

-to

-coarse per 

coarse per 

or agreements to change existing la

or agreements to change existing l

z Ground: Ground:

• Both NMFS and registrants used ve

Both NMFS and registrants used ve

3⁄4 Ground deposition curve Ground deposition curve

z NMFS: 50 NMFS: 50th percentile percentilez Registrants: 90 Registrants: 90th percentile percentile 
Worst-Case Estimates f

Case Estimates f

Habitat Habitat

Habitat Habitat Scena

Scena

Side channel 4 inch depth, 0.0

velocity

Alcove Norwood slough

residence time, 

Backwater AIB, 0.8 ft/sec m

velocity
Worst-Case Aerial Scen

Case Aerial Scen

Each Habitat (1 Each Habitat (1-Day Av

Day Av

NMFS: 159 93 40 21 
Worst-Case Ground Sce

Case Ground Sce

Each Habitat (1 Each Habitat (1-Day Av

Day Av

NMFS: 7.2 4.4 2.1 1.1 
Conservative Features of 

Assessment

3⁄4 Assumed the water body is always 

Assumed the water body is always 

downwind of the treated area downwind of the treated area

3⁄4 Wind speed is always 10 mph Wind speed is always 10 mph3⁄4 Conservative water body geometry 

Conservative water body geometry 

flow/mass exchange conditions we

flow/mass exchange conditions we

where possible where possible

3⁄4 Medium droplet size more likely to 

Medium droplet size more likely to 

in future for both air and ground ap

in future for both air and ground ap

3⁄4 No degradation of chemical in wate

No degradation of chemical in wate

sorption to sediment sorption to sediment
Conclusions Conclusions

3⁄4 Well

-accepted modeling and engineering 

accepted modeling and engineering 

can be used to estimate concentrations in 

can be used to estimate concentrations i

habitats habitats

z Results can be expressed as 1 or 2 Results can be expressed as 1 or 2

-da

da

concentrations to match toxicity studie

concentrations to match toxicity studie

3⁄4 We recommend evaluating additional dat

We recommend evaluating additional dat

become available to extend range of pred

become available to extend range of pred
References References

3⁄4 Bryenton, A.G. 2007. Heat Balance of A

Willamette River, Oregon. MS Thesis, OUniversity, 77 p. Available online at http://ir.library.oregonstate.edu/jspui/hand

3⁄4 Giesy, J. P., Solomon, K. R. Coates J. R.

Giddings J. M., Kenega, E. E. 1999. ChloEcological Risk Assessment in North AmEnvironments. Rev Environ Contam Toxi

3⁄4 Pasternack, G.B., Wang, C.L., Merz, J. 2

of a 2D hydrodynamic model to design of spawning gravel replenishment on the MCalifornia, River Research and Applicatio