# Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load

Submittal Report

October 2004 Publication Number 04-10-043

# Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load

Submittal Report

Prepared by :

Mark Pete rs chm i dt Washington State Departm e nt of Ecology Water Quality Program

October 2004 Publication Number 04-10-043

## For additional copies of this docum ent contact:

Departm e nt of Ecology Publications Distribution Center P.O. Box 47600 Olym pia, WA 98504-7600

Telephone: (360) 407-7472

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## If you need this publication in an alternate fo rmat, please contact us at 360-407-6404 or TTY (for the speech and hearing impaired) at 711 or 1-800-833-6388.

# Table of Contents

List of Tables

............................................................................................................................... .. iii
List of Figures

............................................................................................................................... .. v

Executive S u mm ary

........................................................................................................................ 1

Introduction

............................................................................................................................... ...... 3

Com ponents of the TMDL

.............................................................................................................. 4
Background

............................................................................................................................... ...... 5
Applicable Crite ria

.......................................................................................................................... 9

W a ter Quality and Resource Im pairm e nts

.................................................................................... 11
Technical Approach and Results

.................................................................................................. 12

Technical Assessm ent Objectives an d Strategy

........................................................................ 12

Methods

............................................................................................................................... ...... 13
Results of 2001-2002 Sampling

................................................................................................ 16
Loading Capacity

.......................................................................................................................... 27
Daily DDT and PCB Loads to the Lower Okanogan River and Osoyoos Lake

....................... 27

Source Assessm ent

........................................................................................................................ 32

Load Alloca tions

........................................................................................................................... 35

Load Reductions

........................................................................................................................... 38

Seasonal Va ria tion

........................................................................................................................ 42
Margin of Safety

........................................................................................................................... 42

Summ ary Implem entation Strategy

.............................................................................................. 43
Activities that Support this TMDL

............................................................................................... 49

Im ple m entation Strategy

............................................................................................................... 49
Supporting Regulations and Land Managem e nt Plans

................................................................. 49

Reasonable Assurance

.................................................................................................................. 49

Public Par t icipation

....................................................................................................................... 50

References

............................................................................................................................... ...... 51

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page i

## Definitions and Acronym s

............................................................................................................ 53
Appendix A

............................................................................................................................... .. A-1

Summ ary of Public Involvem ent

............................................................................................ A-2
Responses to Public Comments on the Lower Okanogan River Basin DDT and PCB Subm ittal R e port Draf t

............................................................................................................ A-3
Appendix B

............................................................................................................................... .. B-1

Page ii Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# List of Tables

Table 1: Criteria from Chapter 173-201A WAC .......................................................................10

Table 2: Hum a n Health Criteria from 40CFR131.36 (July 1, 2000 edition) .............................10

Table 3: Im paired Waterbodie s A ddressed in this TMDL .........................................................11

Table 4: Sa m p les Collected During Ecology’s 2001-2002 Assessm ent of DDT and PCBs in the Lower Okanogan River Basin..................................................................14

Table 5: DDT and PCB Concentrations in Lower Okanogan River W a ter, May, 2002 ............17

Table 6: DDT Conce n trations in Tributary Stream s of Osoyoos Lake and the Lower Okanogan River, April-May, 2001a ............................................................................18

Table 7: DDT and PCB Concentrations in Lowe r Okanogan River Basin STP Effl uent, 2001-2002 ....................................................................................................................19

Table 8: DDT and PCB Concentrations in Lower Okanogan River Basin STP Sludge June 2001 (ng/g,dw).....................................................................................................20

Table 9: DDT & PCB Concentrations in Oso yoos Lake Sedim e nt Core Collected June, 2001 (ng/g, dw) ............................................................................................................20

Table 10: DDT and PCB Concentrations in Lower Okanogan River Sedim e nt Core Collected Septem ber, 2001 (ng/g, dw) ........................................................................21

Table 11: DDT and PCB Concentrations in Fillet of Fish from the Lower Okanogan River, 2001 (ng/g, ww) ...............................................................................................25

Table 12: Weighted Mean DDT Loads in Tr ibutary Stream s of Osoyoos Lake and the Lower Okanogan River Based on Water Colum n Sa m p les Collected 1995- 2002 (m g/day) ..............................................................................................................28

Table 13: Mean DDT and PCB Loads in Lo wer Okanogan River Basin STPs Based on Whole Effluent Sam p les (DDT) and PCB Conce n trations in STP Sludge Collected 2001-2002 (mg/day) ....................................................................................29

Table 14: Total Load Delivery, M easured Loads, Theoretical Loads, and Loading Capacities of DDT and PCBs at Se veral Osoyoos Lake and Lower Okanogan River Reach es (m g/day) ...............................................................................................31

Table 15: Measured L o ads of DDT and PCBs at Several L o wer Okanogan River Reaches Compared to L o ads Estim ated from Re- s uspension of Surficial Osoyoos Lake Bed Sedim e nts ( m g/day) ......................................................................35

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page iii

## Table 16: DDT and PCB Load Al locations fo r Individual Tributary stream s ( m g/day) .............36

Table 17: DDT and PCB W a ste Load Allocations for STPs (m g/day)........................................37

Table 18: DDT and PCB Load Al locations for Bottom Sedim e nts (m g/ day) .............................38

Table 19: Required DDT and PCB Load Re ductions and Reserve Capacity (-) at Osoyoos Lake and Lower Okanogan River Reaches (m g/day) ...................................39

Table 20: BSAFs at Osoyoos Lake and Several Lower Okanogan River Reaches .....................40

Table 21: Reductions or Reserve Cap acity (-) in Sedim e nt DDT and PCB Concentrations (ng/g O C ) Required to Meet Load Allocations ..................................41

Table 22: Load Reductions Required to Meet Crite ria with in Indiv i dua l Tribu t ar ies and STPs ( m g/day) .............................................................................................................41

Page iv Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# List of Figur es

Figure 1: O k anogan River W a tershed .............................................................................................6

Figure 2: L o cation of L o wer Okanoga n River and Osoyoos Lake tributary
stream s .............................................................................................................................7

Figure 3: L o wer Okanogan River and Si m ilka m e e n River average m onthly flows (f

igure adap ted f r om WEST Consu ltants, Inc. an d Hamm ond, Collie r, & W a de-Livingstone, Inc., 1999) ..................................................................................15

Figure 4: T

- DDT and t-PCB concentra tions in Osoyoos Lake sedim e nt core .............................22

Figure 5: T

- DDT and t-PCB concentrati ons in lower Okanogan River sedim e nt

core

............................................................................................................................... .23

Figure 6: L i pid-norm a lized t-DDT concen trations in lower O k anogan River fish muscle ordered by m ean length of fis h in each co mposite (Lg = larg e, Md=m edium, Sm =sm a l l ) and location for each species. ..............................................26

Figure 7: L i pid-norm a lized t-PCB concen trations in lower O k anogan River fish muscle ordered by m ean length of fis h in each co mposite (Lg = larg e, Md=m edium, Sm =sm a l l ) and location for each species. ..............................................26

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page v

### Page vi Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Executive Summary

Basin: Okanogan River (W ashington) Key Im paired Resources: Water Quality

Uses Affect ed: Water Supply (Dom es tic), Harvest of aquatic organism s Type of I m p a irm e nt: Concentrations of DDT, 4,4’-DDD, 4,4’-DDE and PCBs in fish Tissue, DDT in W a ter
Pollutant: DDT, 4,4’-DDD, 4,4’-DDE and PCBs

Contribution Factors: Historic agricultura l, ind u strial, com m e rcial and residen t ial practices.

The Okanogan River originates in the Cascade Mountains north of the international border between British Colum b ia and W a shington State. The Okanogan River is characterized by a series of lakes north of international boundary and a free flowing river flowing out of lake Osoyoos, which straddles the boundary, 78 m iles to it ’s conf luence with the Colum b ia River. The Okanogan River’s prim ary tributary is the Sim ilka m een River, which enters 5 m iles south of Lake Osoyoos. The Similkam een River norm a lly c ontributes three quarters of the combined flow in the Okanogan River. The Sim ilka m een River originates on the east slopes of the Cascade Mountains along the inte rnational boarder and m eets th e Okanogan River at Oroville, Washington. Agriculture, forest ry, mining, and recreation are the m a jor land-use ac tivities in the Okanogan watershed.

Under Section 303(d) of the fede ral Clean W a ter Act, the Okanoga n River and several tributaries have been listed by W a s h ington State for non-attain m e nt of the EPA human health criteria for DDT and PCBs in edible fish tissue and for non- attainm e nt of W a shingt on State chronic criteria for DDT in water. Therefore, a Total Maxim u m Daily Load (TMDL) project was conducted for the portion of the river that flow s through W a shington State, as required by the Clean Water Act. The source of these contam inants appears to b e the legacy from historic agricu ltu ral and industrial activities co mmon throughout the Okanogan River watershed.

The chem ical characteristics of DDT and PCBs cau se them t o be classified as persistent, bioaccum u lative toxins. These contam inants are a le gacy of past activ ities as the i r us e has been banned in both the United States and Canada for m o re than 25 years. D u e to the leg acy natu re o f the contam i n ation, subs tantial m itigation of th e D D T and PCB contam ination, both d i rectly and indirectly, has already occurred in the Okanogan Basin. Direct actions include the banning of these m a terials from use; while, indirect acti ons include irrigation im provem e nts that have reduced the loss of agric u ltur a l top s o il th at poten tially could carry pesticide residues to the Okanogan River and associated waterbodies. Th e DDT and PCBs in the lower Okanogan River Basin TMDL continues to prom ote comm un ity actions that address DDT and PCB
contam ination, along with new actions of source identification and develo pm ent of m a nagem e nt strategies to address any sources of contam ination subsequently revealed.

Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 1

### Page 2 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Introduction

Section 303(d) of the federal Cl ean W a ter Act m a ndates that the sta t e o f W a shington estab lish Total Max imum Daily Loads (TM D Ls) for surf ace waters that do not m eet water qu ality standards, designed to protec t, restore and preserve wate r quality, after ap plication of technology-based pollution controls. The U.S. Environm ental Protection Agency (EPA) has established regulations (40 CFR 130) and deve loped guidance (EPA, 1991) for setting TMDLs.

Under the Clean W a ter Act, every s t ate has its own water quality standards designed to protect, restore, and preserve water qua lity. The state’s water quality standards consist of both (1) designated uses, such as supporting cold water biota and providing a drinking water supply, and (2) criteria, usually num eric, require d to achieve those uses. When a lake, river or stream fails to

m eet the water quality standards after applicat ion of required technology -based controls, the Clean W a ter Act requires the stat e to place the water body on a lis t of "impaired " water bodies and to prepare an analysis called a Total Maxim u m Daily Load.

The goal of a TMDL is to ensure that the im paired water will atta in wate r quality stan dards. A TMDL inclu d es a written

, quantitativ e assessm en t of water quality problem s and of the sources that cause them . The TMDL determ ines the amount of a given pollutant that can be discharged to and assimilated by the water body and still m eet st andards; this is called the loading capacity. The TMDL also allocates that load among the various sources, both point and non-point.

The TMDL must also co nsider s easo n al variation s and inc l ud e a m a rgin of saf e ty that takes into account any lack of knowledge about the cause of the water quality problem or its loading capacity. T h e sum of the individual allocations and th e m a rgin of safety must be equal to or less than the loading capacity.

In addition to the m a ndatory com ponents of a TM DL, the general purposes of this docum e nt are to:

• Summ arize data th at docum ent which stream segm ents exceeded standard s for DDT and PCBs.

• Summ arize the results of a techn i cal asse ssm ent which identified probable sources of DDT and PCB contam i n ant load ing that cause increas es in contam inant concentratio ns in f i sh tissue a nd tribu t ary waters.

• Summ arize action s reco mmended for m eeting water quality standards.

• Summ arize monitoring that should be us ed to track TMDL implem entation and determ ine pr ogress towa r d atta ining water qua lit y standards.

A Detailed I m plem entation Plan (DI P ) will be d e veloped within a yea r of TMDL approval by EPA, to expand the in itial im plem entation strate gy into a wo rking plan. Further pub lic inpu t will be sought to help prepare the DIP, which will identify how, when, and where voluntary
resto r ation a c tiv ities will be im plem ented. Deta il s of a m onitoring plan will b e develo ped. The Washington State Departm e nt of Ecology (Ecology) and other ent ities will provide technical assistance and seek additional funding for these activities.

Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 3

## This TMDL addresses th e 303(d) lis t ed water quality im paired water bodies for the DDT and PCBs in the lower Okanogan River basin on the Okanogan River, Lake O s oyoos and the tributary stream s Tallant Creek, Elgin Creek a nd Ninem ile Creek, as well as the unlisted tribu t ar ies o f Antoine Creek and Mos quito Creek. Antoine an d Mosquito Creeks do n o t m e et the state water quality standards based on th e 2001-2002 sam p ling study. The specific water body identification num b ers and im pair m e nts being addressed by this TMDL are: Okanogan River
segm ent ID YN58LL fo r 4,4’-DDD, 4,4’-DDE, PCB-1254 and PCB-126 0 in fish tissue ; Lake Osoyoos ID 060VKD fo r 4,4’-DDD, 4,4’-DDE in fish tissue; and all of the following water bodies for exceeding state chron i c criteria for D D T: Tallant Creek ID LD33FC ; Elgin Creek ID KR66GR ; Ninem ile Creek ID IP09QF ; Antoin e Creek ID NN36KM ; and Mosquito Creek ID QH83DF

.


# Components of the TMDL

The five components of a TMDL, as required by th e Clean Water Act and applied to this TMDL, are described below:

Loading Capacity The loading capacity is the m a xi m u m a m ount of po llutant that a water b ody can receive without violating water quality standard s. Th e loading capacity is allo cated be tween waste lo ad allocations, load allocations, na tural background, and a m a rgin of safety. No natural background value exists for DDT and PCB com p ounds, therefor e no allocation is m a de for it in this TMDL.

Waste Load Allocations A waste load allocation is that portio n of a receiv i ng water' s loading capacity that is a llocated to point sources of pollutio n. There are four pe rm itted wastewater disch a rges to the Okanogan River and its prim ary trib utary, the Sim ilkam een River. Thes e perm itted discharg es r e presen t the m unicipal wastewater treatm e nt plants in Oroville, Tonasket, Om ak and Okanogan. alloc a tion s were calcula ted f o r thes e perm itted discharges b a s e d on their r e spective de sign capacitie s a nd the wate r quality stan dards for DDT, DDE, DDD and PCBs.

Load Allocations A load allocation is that portion of the receiving water' s loading capacity that is allocated to nonpoint sources of pollution or to natural backgrou nd sources. Load allocations for this TMDL are based on the concentration of contam inants in fish tissue in the m a instem Okanogan River and based on the W a shington State ch ronic criteria for DDT in water for selected tributaries.

Margin of S a fety EPA requires that a TMDL include a m a rgin of safety to account for any lack of knowledge concerning the relationship between loads and w a te r quality. This TMDL relies on a m a rgin of saf e ty im plicitly inc l ude d in the con s ervative as s u m p tions th at were c a lc ulated into the

Page 4 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

## regulatory num e rical values c ontained in the National Toxics Rule and the W a ter Quality Standards fo r Surface Waters of th e State of W a s h ington.

Seasonal Variation Seasonal variation, or the changes in loading rates due to changing conditions associated with the annual change in seasons, has been accounted for by sam p ling during both high flow and low flow events. Additionally, the hum a n health and chronic aqu a tic life criteria for DDT and PCBs are driven by long-term exposures. Since the ac cum u lation of DDT and PCBs in fish is a tim e

integrative process, and the chronic aquatic life criteria are based on long-term exposures, seasonal v a r i ations in lo ads are no t a n im portant f actor in de term ining loa d alloc a tion s f o r these
param e ters.



# Background

The Okanogan River flo w s from its headwaters in British Co lum b ia (B.C.) through n o rth-central W a shington, where it d i s c harges into the Colum b ia River near the town of Brewster. T h e Okanogan River basin drains approxim ately 8,900 square m iles of area. The uplands consist mostly of forests and rangelands, while the fertile valley bottom provi des one of the most productive orchard regions in B. C. and W a shington (Figure 1).

Most of the Okanogan River basin lies north of th e Canadian border, where its flow is regulated by four lakes along the river’s m a in stem . All of the lakes are lo cated north of the U.S.-Canada border except the 14,150-acre Osoyoos Lake, which straddles the border. The lower Okanogan River flows out of Osoyoos Lake (elevation 915’ m

. s.l.) at the city of Oroville and flows 79

m iles southward to its confluen ce with the Columbia River (779’ m

. s.l.). The Sim ilkam een River jo ins the Okanogan River jus t downstream of Oroville, where its flow is increased by an average of 400 percent. About 20 sm a ll tributary stream s also drain the 2,600 m i 2 

## of the Washington portion of the basin (h ereinafter referred to as th e lower Okanogan River basin). Most of the tribu t ar ies a r e sm all or in term ittent, c ontribu ting little to the o v erall f l ow of the lower Okanogan River (F igure 2).

The lower Okanogan River basin is located wi thin a sem i -arid region that has an annual precipitation of approxim a tely 20 inches in the higher elevations of the basin fringes, to as little as 10 inches near th e valley bottom

. Surf ace hydrology generally follows a snowm e lt regim e , with low flows occurring Septem ber-March. Se veral of the sm all stream s are div e rte d for irrigation and flow only during releas es from the i r storage reservoirs.

The basin is sparingly populated, with 39,564 re sidents in Okanogan County according to the 2000 census. The cities of Om ak and Okanoga n have a com b ined population of about 7,000. Other population centers include the cities of Oroville ( ≈ 1,600) and Tonasket ( ≈ 1,000). The southern portion of the lower Okanogan River provides the western boun dary of the Colville Indian Reservation from river m ile (RM) 38.6 dow nstream to its confluence with the Colum b ia River.

Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 5

## Land cover is prim arily forest and rangeland, especi ally in the uplands. N ear the valley bottom

, orchards and pasture/hay are the pr im ary agricultural uses. F r uit orchards have a long history in the Okanogan valley, with the first planted in 1857. By 1916 there were approxim a tely 12,000 acres of irrigated orchards in the lower Oka nogan River valley. Fruit orchards presently

com p rise about 2 percent or approxim ately 37,000 acres of the land area. The upper Okanogan River basin (north of the Cana dian b o rder) h a s a sim ilar com position of orchard lands, providing over 99 percent of the tree fruit grow n in Br itish Colum b ia (Sinclair and E llio tt, 1993 ).

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### Figure 1: Okanogan River Watershed

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### Figure 2: Location of Low er Oka nogan River and Oso yoos Lake Tributary Streams



## Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 7

### Page 8 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Applicable Criteria

W ithin the state of W a shington, water quality st andards are published pursuant to Chapter 90.48 of the Revised Code of Washington (RCW ). Au thority to adopt such rules, regulations, and standards as are necessary to pr otect the environm ent is vested with the Departm e nt of Ecology. Under the f e deral Clean W a ter Act, the EPA Re gional Adm i nistrator m u st approve the water quality standards adopted by the State (Section 303(c)(3)). T h rough adoption of these water quality standards, W a shington has designated certai n characteristic uses to be protected and the criteria necessary to protect these uses [W as hington Adm i nistrative C ode (WAC), Cha p ter 173- 201A].

Stream s in the lower Okanogan Basin watershed ha ve the following designated uses assigned in Chapter 173-201A W A C, Table 602. The designated uses are:

• Aquatic Life Uses

o Non-Core Salm on/Trout: Salmon an d trout spawning, non-core rearing, and

m i gration. For the protect ion of spawni ng, n on-core rearing, and migration of salm on and trout, and other 

## associated aquatic life.

• Recreational Uses

o Prim ary Contact

• Water Supply Uses

o Dom e stic W a ter

o Industrial Water

o Agricultura l W a ter

o Stock W a ter

• Miscellan e o u s Uses

o W ildlif e Habita t

o Harvesting

o Comm erce/Navigation

o Boating

o Aesthetics

This TMDL is designed to address impairm e nts of designated uses caused by DDT and PCB concentrations in fish tissues and surface waters.

Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 9

## Chapter 173-201A W A C contains DDT and PCB cr iteria to protect aquatic life (T able 1). Because th is criteria does not include a hum an he alth com ponent and does not protect all designated uses (i.e. use of water as a dom e stic supply and harvesting of organism s), the Clean W a ter Act r e quires the a ddition a l us e of the water quality c r iter ia se t in National To xics Rule, Chapter 40 of the Code of Federal Regulati on part 141.36 (40CFR131.36). The National Toxics Rule (NTR) defines the criteria for DDT, DDD, DDE and PCBs for the protection of hum a n health. The num e ric criter ia are given in Table 2.

Table 1: Criteria from Ch apter 1 7 3

- 20 1A WAC

Toxics Subs tanc es Cri t er ia (μg/L)

Fresh w a ter Substa nce Acu t e Chronic
DDT (an d me tabolites) 1.1a 0.001b Polychlo rinat ed Biphenyl s (PCBs) 2.0b 0.014b

Notes to Tab l e 1 : a. An ins t an tan e ous concen tra tio n not to b e exce e d ed a t an y t i m e

. b. A 24-hour av e r age no t to be ex ceed ed.



### Table 2: Hu man Health Criteria from 40CF R 13 1.3 6 (July 1, 2000 edition )

Hum a n Healt h (10 -6 

### risk for carcinog ens )

for th e cons umption of:

Wa ter & O r g a nism s Organisms Only (#) Compou nd CAS Num b er (μg/L) (μg/L) (108 ) 4,4' -DDT 5029 3 0.0005 9 0.0005 9 (109 ) 4,4' -DDE 7255 9 0.0005 9 0.0005 9 (110 ) 4,4' -DDD 7254 8 0.0008 3 0.0008 3



### Page 10 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Water Quality and Resource Impairments

The lower Okanogan River, Osoyoos Lake and thei r W a shington State tributaries of Ninem ile Creek, Sim ilkam een River, Tallant C r eek, and unnam e d (Elgin) creek were included in Washington’s 1998 list of i m pa ired waters com p iled under S ec tion 303(d) of th e Clean W a ter Act due to water quality im pair m e nts by DDT, 4-4’-DDD, 4,4’-DDE, PCB-1254, PCB-1260, Dissolved O xygen, Fecal Coliform

, Arsenic, and Te m p erature. In additio n to the 303 (d) listed im paired waters the lower Okanogan River tribut aries Antoine Creek and Mosquito Creek were found to be impaired by DDT (Serdar 2003). This TMDL addresses the water quality im pair m e nts fro m DDT, 4,4’-DDD, 4,4’- DDE, PCB-1254, PCB-1260 included in Table 3.

Table 3: Imp a ired Wa ter b odies Add r e ssed in this TMDL

Wa terbo d y Old Segment No. Ne w Segment No. To w n ship, Rang e & Section Impairment(s) Years listed on the 303(d) Lis t: Okanog an River W A -49-10 10 YN58 LL 31N, 25E,

Section 2 7 Exce eds NT R criteria for 4,4’-DD D , 4,4' -DDE, and PCB- 12 54 in fish tissue a 199 6

199 8

Okanog an River W A -49-10 10 YN58 LL 31N, 25E,

Section 3 4 Exce eds NT R criteria for PCB-1260 in fish tissue a 199 6

199 8

Oso y oos Lk. W A -49-92 60 060VK D 40N, 27E,

Section 2 2 Exce eds NT R criteria for 4,4’-DD D , 4,4’- DDE in fish tissue b 199 6

199 8

T a llant Creek W A -49-10 17 LD3 3 F C 32N, 25E,

Section 0 2 Exce eds W a sh ingto n State chronic criteria for

DDT in w a ter c 199 8

Elgi n Creek

(listed as Unn a med

Creek) W A -49-10 22 KR66GR 33N, 26E,

Section 0 3 Exce eds W a sh ingto n State chronic criteria for

DDT in w a ter c 199 8

Ninem ile

Creek W A -49-10 49 IP09QF 40N, 27E,

Section 1 5 Exce eds W a sh ingto n State chronic criteria for

DDT in w a ter c 199 8

Antoin e Cre e k NN36 K M 38N, 27E

Section 2 7 Exce eds W a sh ingto n State chronic criteria for

DDT in w a ter d Unliste d but impair ed

Mosquito

Creek QH83Df 38N, 27E

Section 2 7 Exce eds W a sh ingto n State chronic criteria for

DDT in w a ter d Unliste d but impair ed

NTR=Nation a l Toxics Ru le

a Davis and Serd ar, 1996

b Johnson and Norton, 1990

c Johnson et al., 1997

d Serdar, 2003



## Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 11

# Technical Appr oach and Results

An approach of m a ss balancing was used in the Low er Okanogan River Basin DDT and PCBs Total Maximum Daily Load TMDL evaluation for DDT and PCB com p ounds in the lower Okanogan River basin. The m a ss ba lancing was used to evaluate the sources of contam inant loading and their potential im pact s to the water quality in the ba sin. This study approach used several tech niques for th e collect ion of surface water d a ta, s e dim e nt data, fish tissue d a ta and discharg e in f o rm ation f r om the NPDES perm itted discharg er s. Data collected was us ed to asse ss potential D D T and PCB sources and to com p are data from the current study to other data sources. (Serdar 2003)


# Technical Assessment Objectives and Strategy
During 2001 – 2002, Ecology collected data necessary to conduct a TMDL assessm ent for the geographic area and param e ters covering the lower Okanogan River and all of its tributaries from the Canadian border (R M 82.5) to its m outh near Brewster, including the southern portion of Osoyoos Lake (RM 79.0 – 82.5). The TMDL concerns 4,4’-DDD, 4,4’-DDE, 4,4’-DDT, t-DDT, and PCBs (as Aroclors or t-PCB). Objectives of the sam p ling were to assess DDT and PCB loads to the lower Okanogan River and Osoyoos La ke, assess DDT and PCB concentrations in edible fish tissue, and reconstruct historic DDT and PCB levels in sedim e nts. This was considered necessary to achieve the goal of the lower Okanogan TM DL project – to determ ine if and where DDT/PCB loading m a y be reduced and how this may affect their concentrations in fish tissue.

Early in the planning process it wa s recognized that this would not be a traditional T M DL. First, although D D T and PCBs have been banned for d ecades, th ey persist in the environ m ent and generally have becom e non-point contam inants often dissipated and dispersed far from their original sources. Second, the li stings in the lower Okanogan Ri ver and Osoyoos Lake are based on fish tissue, adding layers of complexity to ca lcula ting loa d s and load alloc a tion s , custom ary elem ents of a TMDL assessm ent.

The need to approach this TMDL assessm ent fr om a broad geographical perspective was also recognized as a potential difficulty early in the planning process. The distribution of agricultural lands and results of previous Ecology studies suggested DDT contam ination existed throughout the lower O k anogan River valley. T h e geographi cal locations of PCB co ntam ination were less certain, but the problem was addr essed basin-wide rather than focusing on a single listed river reach.

Given these and other considera tions, four sam p ling com pone nts we re identified to carry out the TMDL assessm ent:

• Re-assessm ent of DDT a nd PCB loads transported to the lower Okanogan River and Osoyoos Lake through tributaries and discharg ed by m unicipal sewage treatm e nt plants.

• Measurem ent of DDT and PCB concentratio n s in the wate r colum n of the lower Okanogan River.

Page 12 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

## • Analysis of DDT and PCB concentrations in edible fish tissue from the lower Okanogan River.

• Analysis of DDT and PCB concentrations in sedim e nt cores from the lower Okanogan River and Osoyoos Lake.

The following sections describe m e thods for co llecting data f o r these study com ponents and

sam p le results. A TMDL analysis is then pe rform e d to quantify load s to the lower O k anogan River and Osoyoos Lake. Also inclu d ed is a quantitativ e analysis of DDT/PCB accumulation by fish in the lower Okanogan River and Osoyoos Lake . These analyses were perform e d using data collected during 2001-2002, as well as previous Ecology data and data collected by other agencies.



# Methods

Sa m p ling Strategy
Sa m p le types, sam p le locations, and analyses were all conducted to best m eet the project objectives. Table 4 summ arizes samples collected during 2001-2002.

Lower Okanogan River and Osoyoos Lake tributaries were sampled for DDT in the present

assessm ent during the high flow s eason (April-M ay) when more str eam s contain water than o t her tim es of year. Previous sam p ling of tribut ary stream s was conducted during low flows (JulyAugust) (Johnson et al., 1997). PCBs were not anal yzed in water from tributaries since they are
extrem ely difficult to detect in water without expe nsive specialized m e thods. There is also little
reason to su spect these s t ream s contain m easurable PCBs sinc e they a r e pr im arily an in dustrial and urban contam inant.

W a ter f r om the th ree m u nicipa l sewa ge tre a tm ent plants (STPs) disch a rging to the lo wer Okanogan River or S i m ilkam een River – Oroville, Om ak, and Okanogan – were also sam p led for DDT and PCBs (Tonasket STP began discharg ing to the Okanogan River after sam p ling for this project had been completed). S T Ps m a y act as funnels for DDT in urban areas (Reif, 1990) possibly due to im proper disposal or storage and historic non-agric u ltu ral insec tic idal uses such

as m o squito control. Previous studies have not adequately investigated D D T in STP e ffluent. PCBs were also sam p led in STP effluent s i nce S T Ps represent the few places in the b a sin where PCBs m a y be present at detect able concentrations, due, for in stance, to the high density of electrical transfor m e rs in the service area com p ared to other pa rts of the basin. The only known analysis of PCBs in a lower Okanogan Rive r basin water sample was from Okanoga n STP effluent analyzed in 1988 by Reif (1990). No PCBs were detected in this sam p le.

Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 13

### Table 4: Sa mples Colle cted During Ecolog y ’ s 2001-2 002 Ass essmen t of DDT a nd PCBs in the Lo w e r O kan ogan Riv e r Basin

Loca t ion W hole Water a 

### Sediment/Sludge b 

### Fish Tissue c

Oso y oos Lak e -- Core – D D T / PCBs + chlori nate d pes ticides --

Mainstem Oka nog an Riv er

Oroville R eac h DDT /PCBs -- DDT /PCBs

Riversi de-Oma k Reach DDT /PCBs -- DDT /PCBs

Malott-Mons e Reac h DDT /PCBs Core – D D T / PCBs + chlori nate d pes ticides DDT /PCBs

T r ibutar y Strea m s DDT

(DDT /PCBs in Similkam ee n R

. ) -- --

ST Ps DDT /PCBs Slud ge – DDT /PCBs --

a ancill ar y ana l y s es inc l uded TS S

, TOC, and f i eld parameters
b anci llar y an al ys es inc l uded TOC and 210 Pb

c ancill ar y ana l y s is inc l uded p e rc e n t lip ids



## STP sludge was also exam ined for DDT and PCBs since it provides a m o re feasible m e dia for detection of these ch em i cals due th eir tendency to sorb to organic-rich solids. In the absence of detectable concentrations in e ffluent, sludge was used to calcul ate crude estim ates of DDT and PCB loads via STPs.

High flow data were collected to supplem e nt pr eviously reported low flow data in order to address potential seasonal variat ion. W a ter column sa m p les were collected at three locations in the lower m a instem Oka nogan River in May dur ing the rising lim b of the season hydrograph (Figure 3), since rising flows are m o s t likely to entrain DDT-containing particulate m a tter. Sa m p les were also analyzed for PCBs. Sam p li ng locations w e re at the Osoyoos Lake outlet to

assess con t am inant loads from across the border; at Riverside just upstream of the largest urban center in the lower Okanogan River basin; and at Malott below urban centers and near the Okanogan River m outh. Sa m p les were also collec ted at the mouth of the Sim ilka m een River.

Page 14 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

### Figure 3: Lo w e r Ok anog an Riv e r and Similkameen Riv e r A v er age Mon t hly Flo w s (fig u r e adap ted from WEST Consultan t s, Inc. and Hammond, Collier, & Wade-Liv ingstone, Inc., 1999)



## To assess the geographical distribution of cont am inants in lower Okanogan River fish, three species were sam p led from the upper river (Oroville reach, RM 77.3 – 76.4), m i ddle river (Riverside-Om a k reach, RM 41.0 – 30.7), and lowe r river (Monse reach, RM 10.5 – 4.9). These three reach es also enco mpass three of the popul ation centers and public boat laun ches along th e river.

Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 15

## Species an alyzed were comm on carp ( Cyprinus carpio ), m o untain whitefish ( Prosopium williamson i ), and sm allmouth bass ( Micropterus dolomieui ). These are the three m o st comm on resident gam e species in the lower Okanogan Rive r and represent different feeding behaviors and habita t uses. Edible tiss ue (f illet) w a s analy zed for DDT and PCBs. Re sults were provided to Washington State Departm e nt of Health (W DOH) for their assessm ent of a ny potential hum a n health risk s associated w ith consum ption of each species.

Sedim e nt cores were co llected to reco nstruct historical DDT and PCB concentration s from sedim e nt deposits. Two to four decades have pa ssed since D D T and PCBs were banned or their use peaked in the U.S. and Canada, and concentr ations in the aquatic environm ent have since been declining. However, exis ting lower Okanogan River basin da ta are not sufficient to gauge trends over tim e . In the absence of previously established baselines, sedim e nt coring is the best

m e thod to reconstruct historic contam ination levels.

Due to the h i gh labo rato ry costs asso ciated with a n alyzing m u ltip le sed i ment hor izons , coring was lim ited to two sites: southern Osoyoos Lake and the m o uth of the Okanogan River near Monse. These sites m a y represent the only locati ons in the basin with sedim e nt deposits deep enough to reconstruct co ntam ination levels going back several decades.

Field procedures, sam p ling locations, laborat ory procedures and data quality assurance procedures are contained in the Okanogan T echnical Assessm ent Report (Appendix B, Serdar 2003).



# Results of 2001-2002 S a mpling

Com p lete results of 2002-2002 sampling are in Appendix F.

DDT and PCBs in the Lower Okanogan River Mainstem Water Colum n Table 5 shows results of water column sa m p li ng conducted in the lower Okanogan River during May 2002. Co m p arable concentrations of 4,4’-DDE and 4, 4’-DDD (0.14 – 0.29 ng/l) were found at all three lower Okanogan Ri ver sites. None of the nine PCB Aroclors analyzed were detected at practical quantit ation lim its of 0.64 – 0.67 ng/l.

These results represent the first tim e DDT com p ounds have been detected in the water colum n of the lower O k anogan River. Previous sam p li ng during 1995 by Johnson et al. (1997) f a iled to detect DDT in the lower Okanogan River at a practic al quantitation lim it of 1 ng/l. Therefore, it is im possible to determ ine if the 2002 results represent a change from 1995 levels. The May 2002 concentrations probably w ould have gone undetected had Metro Environm ental Laboratory (MEL) not used the large volum e injecti on to achieve low quantitation lim its ( ≤ 0.1 ng/l).

Page 16 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

### Table 5: DDT and PCB Concen tra t ion s in Lo w e r O kanog an Riv e r Wa ter, Ma y , 2002

Loca t ion RM Dat e Flo w (l/s) TSS (mg/l) 4,4'-DDE (ng/l) 4,4'-DDD (ng/l) 4,4'- DDT (ng/l) t- DDT (ng/l) PCBs a 

### (ng/l) Okanog an R. @ Zosel Dam 7 7

. 4 5 / 1 3 / 0 2 33,13 1 1 8 0

. 2 3 0

. 2 9 u(0.08 0 ) 0

. 5 2 u ( 0

. 6 6 ) Okanog an R. @ Riversi de 4 0

. 6 5 / 1 3 / 0 2 137,6 2 0 2 0 0

. 2 2 0

. 1 4 u(0.07 6 ) 0

. 3 6 u ( 0

. 6 6 ) Okanog an R. @ Malott 1 7

. 0 5 / 1 4 / 0 2 146,6 8 1 2 6 0

. 1 7 0

. 1 6 u(0.10) 0

. 3 3 u ( 0

. 6 4 )

a Results shown are fo r PCB Aro c lors 1268, 1262 , 1260 , 1254 , 12 48, 1242 , 1232

, 1221, and 1016 u=undetected at practical qu an titation limit in par e ntheses



## DDT in Osoyoos Lake Tributaries an d Lower Okanogan River Tributaries
DDT concentrations in water co llected near the mouths of Osoyoos Lake and lower Okanogan River tributaries are shown in Table 11. Thes e represent all of the tributary stream s found flowing during the April and May 2001 sam p ling events, ex cept for the S i m ilkam een River which was sam p led during May, 2002. In all, 18 stream s were sam p led and 13 were found flowing during both April and May sam p ling events. This is about twice the num ber of stream s

sam p led during July-August 1995 even though th e 2001 water year was extraordinarily dry.

DDT was de tected in water from 12 s t ream s w ith t-DDT concentrations ranging from 0.4 – 9.2 ng/l. 4,4’-DDE was the prim ary m e tabolite de tected, with 4,4’-DDT present at the second highest concentration, unlike lo wer mainstem Oka nogan River sam p les which had no m easurable 4,4’-DDT. Low concentrations of 2,4’-DDT ( ≤ 0.5 ng/l) were also detected in several creeks. Antoine Creek had 2,4’-DDD at 1.3 ng/l during April 2001 sam p ling.

Elgin Creek in the lower part of the basin (R M 28.4) had the highest t-DDT concentrations, followed by Antoine Creek and Nine Mile Creek, which is an Osoyoos Lake tributary. This partially m i rrors the 1995 study which found these stream s to have som e of the highest DDT concentratio ns and is ind i cative of a pattern showing stream s w ith high DDT concentrations in the upper and lower parts of th e basin (RM 61-80 and RM 15-28). Little or no DDT was found in the m i ddle basin (RM 32-57), especially RM 32-51 where no DDT at all was detected.

Tallan t Creek was not sampled in the present st ud y because it was dry. This creek gen e rally contains water only during late su mm er or early autum n due to releases from Leader Lake, its prim ary source. W h en Tallant Creek was sam p l e d in 1995, t-DDT concentrations up to 500 ng/l were found and Tallant Creek c ontributed about 75% of the DDT load to the lower O k anogan River during that period.

No DDT wa s detected in the Sim ilkam een River during May 2002 sam p ling even though the large volume injection m e thod used for this sa m p le provided quantitation lim its an order of

m a gnitude lower than in other tribu t aries. PCBs Aroclors w e re also analyzed in the Sim ilka m een River water sam p le, but none were detected at a quantitation lim it of 0.67 ng/l.

Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 17

### Table 6: DDT Conc entr a t ions in Tributar y Streams of Osoy oo s Lake and the L o w e r Okan ogan Riv e r, April-Ma y , 2001 a



### Loca t ion RM Dat e Flo w (l/s) TSS (mg/l) 4,4'-DDE (ng/l) 4,4'-DDD (ng/l) 4,4'-DDT (ng/l) t- DDT (ng/l)
Nine Mi le Cr ee k 80.2 4/17/ 0 1 9 9 1 2 1

. 8 0

. 4 1

. 3 3

. 5

“ 5 / 1 6 / 0 1 3 2 u ( 1 ) 1

. 4 0

. 6 1

. 5 3

. 5
T onasket Cree k 77.8 4/17/01 3 6 1 4 1

. 5 u ( 0

. 8 ) 1 2

. 5

“ 5 / 1 6 / 0 1 2 6 9 1

. 2 u ( 1

. 7 ) 1

. 1 2

. 3 Similkam ee n R i ver 74.1 5/13/02 113,5 51 1 4 u ( 0

. 0 6 7 ) u(0.06 7 ) u ( 0

. 0 8 0 ) n d Mosqu i to Cree k 67.4 4/11/01 0

. 2 4 7 0

. 8 0

. 7 u ( 0

. 8 ) 1

. 5

“ 5 / 1 6 / 0 1 0

. 5 2 1

. 7 0

. 4 1

. 4 3

. 5
W h itestone Cr eek 62. 4 4 / 1 1 / 0 1 1 1 4 1 0 0

. 6 u( 0

. 8 ) u ( 0

. 8 ) 0

. 6

“ 5 / 1 6 / 0 1 8 5 5 0

. 4 u( 1

. 6 ) u ( 1

. 6 ) 0

. 4
Antoin e Cre e k 61.2 4/17/ 0 1 1 0 1 2 5

. 2 1

. 1 1

. 7 8

. 0

“ 5 / 1 6 / 0 1 3 1 1 6 1

. 8 0

. 5 1 3

. 3 Si w a s h Creek 57.3 4/16/01 24 1 0

. 5 u ( 0

. 8 ) u ( 0

. 8 ) 0

. 5

“ 5 / 1 6 / 0 1 0

- - - - - - - - - - Bona parte Cr e e k 56.7 4/11/01 62 2 1 0

. 4 u ( 0

. 8 ) u ( 0

. 8 ) 0

. 4

“ 5 / 1 7 / 0 1 1 5 3 5 5 0

. 4 u( 1

. 7 ) u ( 1

. 7 ) 0

. 4
Aene as Cre e k 52.9 4/16/01 95 u( 1 ) 0

. 4 u(0.8) u ( 0

. 8 ) 0

. 4

“ 5 / 1 7 / 0 1 7 8 2 0

. 4 u( 1

. 6 ) u ( 1

. 6 ) 0

. 4 Che w i lik en Cr e e k 50.7 4/11/01 9 u( 1 ) u ( 0

. 8 ) u(0. 8 ) u ( 0

. 8 ) n d

“ 5 / 1 7 / 0 1 0

- - - - - - - - - - T unk Creek 45.0 4/16/01 106 2 u ( 0

. 9 ) u ( 0

. 9 ) u ( 0

. 9 ) n d

“ 5 / 1 7 / 0 1 1 9 7 1 6 u(1.7) u ( 1

. 7 ) u ( 1

. 7 ) n d
Johns on Cre e k 40.6 4/16/01 79 11 u ( 0

. 8 ) u ( 0

. 8 ) u ( 0

. 8 ) n d

“ 5 / 1 7 / 0 1 2 9 1 2 u(1.7) u ( 1

. 7 ) u ( 1

. 7 ) n d
W anacut Cre e k 35.0 4/12/01 29 1 u ( 0

. 8 ) u ( 0

. 8 ) u ( 0

. 8 ) n d

“ 5 / 1 7 / 0 1 1 4 1 u(1.7) u ( 1

. 7 ) u ( 1

. 7 ) n d Omak Creek 32.0 4/12/01 382 5 u ( 0

. 8 ) u ( 0

. 8 ) u ( 0

. 8 ) n d

“ 5 / 1 5 / 0 1 5 9 6 3 5 u(1.7) u ( 1

. 7 ) u ( 1

. 7 ) n d Elgi n Creek 28.4 4/12/01 2 7 7 3

. 7 0

. 4 1

. 8 5

. 9

“ 5 / 1 5 / 0 1 1 9 2 0 5. 8 0

. 9 2

. 5 9

. 2 Salmo n Creek 25.7 4/17/01 284 1 0

. 4 u ( 0

. 9 ) u ( 0

. 9 ) 0

. 4

“ 5 / 1 5 / 0 1 0

- - - - - - - - - - T a l l a n t C r e e k 1 9

. 5 4 / 1 6 / 0 1 0

- - - - - - - - - -

“ 5 / 1 5 / 0 1 0

- - - - - - - - - - Lou p Lo up Cre e k 16.9 4/16/01 0 -- -- -- -- --

“ 5 / 1 5 / 0 1 3 u ( 1 ) 0. 7 u ( 1

. 6 ) 0

. 7 1

. 4 Chil i w ist Cre e k 15.1 4/16/01 71 1 1 0

. 4 u ( 0

. 8 ) u ( 0

. 8 ) 0

. 4

“ 5 / 1 6 / 0 1 2 7 1 u(1.7) u ( 1

. 7 ) u ( 1

. 7 ) n d

a Similkameen River samples May

, 2002 u=undetected at practical qu an titation limit in par e ntheses
nd=not d e tected



## DDT and PCB Concentrations in S T Ps
Three m unicipal sewage treatm ent plants (STP s) were sam p led for DDT a nd PCBs during 2001. The Om ak STP and Okanogan STP discharge treated effluent directly to the Okanogan River

Page 18 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

## while the Oroville STP effluent is discharged to the Sim ilka m een River approxim a tely four m iles upstream of the form al confluen ce with the Okanogan River. Sa m p les of final effluent were collected on three o ccas ions and slud ge was collected once.

Table 7 shows results of DDT and PCB analysis of STP e ffluent sam p les. Table 8 shows results of sludge samples analyzed for DDT and PCBs. DDT was de tected in Oroville and Okanogan STP effluent on two occasions, with t-DDT concen trations (0.7 – 1.8 ng/l) com p arable to those found in tributary streams. No evidence of PCBs were found in a scan of the April, 2001 and May, 2001 sam p les. Samples collected during Ma y, 2002 were analyzed for PCBs only using a large volume injection m e thod. A l o w con centration of PCB-1248 (0.39 ng/l) was f ound in Okanogan STP effluent, but no other PCBs were detected.

DDT and PCBs were detected in sludge from al l three STPs, with the h i g h est concentrations from the Oroville STP. The t-PCBs were found at higher concentrations than t-DDT in sludge unlike effluent sam p les where DDT concentrations were higher. This m a y suggest that, while both DDT and PCBs are present in S T Ps, PCBs a r e m o re strongly sequestered in solids. The Om ak STP c onsistently showed the lowest concen trations of DDT in both m e dia and of PCBs in sludge, even where the T SS and TOC conten t – factors often correlated with higher concentrations of organochl orine compounds – was highest.

Three of seven PCB Aroclors analyzed in sludge were detected; PCB-1260, -1254, and -1248. These are th e m o st common Aroclors detected in W a shington’s freshwat er aquatic environm ent both statewide (e.g. Hopkins et al ., 1985; Davis et al., 1995; Davis and Serdar, 1996) and at sites with known PCB sources (e.g. Ecology, 1995). As m e ntioned previ ously, PCB-1248 was the only Aroclor detected of the nine analyzed in effluent sam p les.

Table 7: DDT and PCB Concen tra t ion s in Lo w e r O kanog an Riv e r Basin ST P Effluent, 2 001-200 2

Loca t ion RM Dat e Flo w (l/s) TSS (mg/l) 4,4'-DDE (ng/l) 4,4'-DDD (ng/l) 4,4'-DDT (ng/l) t- DDT (ng/l) PCBs a 

### (ng/l)

Oroville ST P b 4/17/01 6 1 0

. 5 u ( 0

. 9 ) 0

. 6 1

. 1 n d *

5 / 1 6 / 0 1 7 u ( 1 ) u(1.7) u ( 1

. 7 ) 0

. 7 0

. 7 n d *

5 / 1 4 / 0 2 7 u(1) n a n a n a n a u(0.63) c

Omak ST P 29.9 4/17/01 24 2 u(0. 8 ) u ( 0

. 8 ) u ( 0

. 8 ) n d n d *

5 / 1 7 / 0 1 2 6 4 u ( 1

. 6 ) u ( 1

. 6 ) u ( 1

. 6 ) n d n d *

5 / 1 3 / 0 2 2 6 3 n a n a n a n a u ( 0

. 6 6 ) Okanog an ST P 2 4

. 8 4 / 1 6 / 0 1 1 6 4 0

. 7 u( 0

. 8 ) 0

. 6 1

. 3 n d *

5 / 1 7 / 0 1 1 6 4 0. 4 0

. 4 1 1

. 8 n d *

5 / 1 4 / 0 2 1 1 5 n a n a n a n a 0.39 d

a Results shown are for PCB Aroclors 1268, 1262, 1260, 1254 , 124 8, 1242 , 1232 , 1 221, and 1016

b Sim ilkam een Ri ver m ile 4.0

c Practical qu antitation limit was 0

. 94 ng/l for PCB-1254

d Concentr ation o f PCB-1248. Other Aroclo rs und etec ted at a pr actical quan titation limit of 0.65 ng/l u=undetected at practical qu an titation limit in par e ntheses nd=not d e tected *no practical qu antitatio n limit d e termined



## Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 19

### Table 8: DDT and PCB Co ncen tratio ns in Lo w e r Ok anogan Riv e r Basin STP Sludge
June 200 1 (ng/g,d w )

Loca t ion %T O C 4,4'- DDE 4,4'- DD D 4,4'- DDT t- DDT PCB1260 PCB1254 PCB1248 t-PC B a
O r o v i l l e ST P 3 6

. 7 1 8 0 2 6 3 6 2 4 2 4 8 1 3 0 9 5 2 7 3
O m a k ST P 4 0

. 3 6 8 u ( 4 5 ) 2 3 9 1 4 1 1 0 0 6 3 2 0 4 Okanog a n ST P 3 2

. 0 1 1 0 2 3 4 0 1 7 3 5 1 1 2 0 6 3 2 3 4

a Aroclors 1242, 1232, 1221 , and 1016 not d e t ect ed at practi cal qu antit ation l i m its of 43 ng/g (Orov ille STP), 45 ng/ g (Om a k STP), and 42 ng/g (Okanogan STP) u=undetected at practical qu an titation limit in par e ntheses



## DDT and PCB Concentrations in Sedim e nt Cores
Sedim e nt cores were collected to reconstruct the history of DDT and PCB deposition in Osoyoos Lake and the lower Okanogan River. A rela tively deep core (approxim a tely 45 cm ) was obtained at the southern end of Os oyoos Lake (T able 9). Penetrati on was not as deep in the core collected near the Okan ogan Rive r mouth (Table 10). Deposition of fine sedim e nts near the mouth of the Okanogan River m a y not have o ccurred until the for m ati on of Lake Pateros (consequently backing-up the Okanogan River ne ar the m outh) in 1967, and, therefore, bottom sedim e nts pre-dating 1967 are prob ab ly absen t at this site.

Table 9: DDT & PCB Co ncen tratio ns in Oso y oos Lake Sedime nt Cor e Collected Ju ne, 2001 (ng/g, d w ) Dep t h Interv al

(cm ) Year Depo sited %T O C 4,4'- DDE 4,4'- DD D 4,4'- DDT tDDT PCB1260 PCB1254 PCB1248 tPCB a

0

- 1 2 0 0 1

. 0 4

. 3 7 % 3 5 4 3 3 8 1 u ( 2

. 8 ) u ( 2

. 8 ) 1

. 1 1

. 1

1

- 2 1 9 9 9

. 0 3

. 7 8 % 3 2 4 2 0

. 7 9 7 5 u ( 5

. 4 ) u ( 5

. 4 ) u ( 5

. 4 ) n d

2

- 3 1 9 9 8

. 8 4

. 2 5 % 7 5 7 7 9 6 2 4 8 u ( 5

. 4 ) u ( 5

. 4 ) 2

. 2 2

. 2

3

- 4 1 9 9 8

. 5 4

. 0 3 % 3 4 3 9 1 3 8 6 u( 5

. 3 ) u ( 5

. 3 ) u ( 5

. 3 ) n d

4

- 5 1 9 9 8

. 3 4

. 4 7 % 3 9 4 4 u ( 5

. 3 ) 8 3 u ( 2

. 6 ) 0

. 7 9 u ( 2

. 6 ) 0

. 7 9

6

- 7 1 9 9 6

. 5 4

. 2 3 % 3 7 2 0 1 5 8 u ( 2

. 5 ) 0

. 7 4 u ( 2

. 5 ) 0

. 7 4

8

- 9 1 9 9 3

. 5 4

. 0 5 % 3 7 3 8 1 3 8 8 u ( 2

. 3 ) u ( 2

. 3 ) 1

. 2 1

. 2

10-1 1 1 9 9 1 3

. 9 3 % 3 8 4 3 4 8 5 u ( 2

. 2 ) u ( 2

. 2 ) 1

. 1 1

. 1

13-1 4 1 9 8 8 3

. 9 9 % 3 5 4 5 4

. 8 8 5 u ( 2

. 0 ) u ( 2

. 0 ) 1

. 0 1

. 0

16-1 7 1 9 8 5 3

. 7 2 % 3 9 4 7 1

. 8 8 8 u ( 1

. 9 ) 0

. 7 5 u ( 1

. 9 ) 0

. 7 5

19-2 0 1 9 8 1 3

. 6 0 % 3 6 5 4 6

. 4 9 6 u ( 1

. 7 ) u ( 1

. 7 ) 0

. 8 5 0

. 8 5

23-2 4 1 9 7 6 3

. 0 4 % 9 2 1 5 0 1 2 2 5 4 u ( 3

. 3 ) 2

. 7 2

. 0 4

. 7

27-2 8 1 9 6 7 2

. 4 3 % 4 2 9 2 1

. 6 1 3 6 u ( 2

. 9 ) 1

. 4 u ( 2

. 9 ) 1

. 4

31-3 2 1 9 5 7 2

. 1 2 % 2 1 4 8 3

. 5 7 2 u ( 2

. 7 ) u ( 2

. 7 ) u ( 2

. 7 ) n d

35-3 6 1 9 4 5 1

. 9 3 % 3

. 7 8

. 6 u ( 0

. 6 1 ) 1 2 u(2.5) u ( 2

. 5 ) u ( 2

. 5 ) n d

39-4 0 1 9 3 2 1

. 7 6 % 2

. 2 5. 1 u ( 0

. 5 6 ) 7

. 3 u(2.2) u ( 2

. 2 ) u ( 2

. 2 ) n d

44-4 5 1 9 1 7 1

. 7 6 % u(0.55) 0

. 2 2 u ( 0

. 5 5 ) 0

. 2 2 u(2. 2 ) u ( 2

. 2 ) u ( 2

. 2 ) n d

a Aroclors 1242, 1232, 1221 , and 1016 not d e tected at practical qu antitation limits of 1.7 – 5

. 4 ng/g u=undetected at practical qu an titation limit in par e ntheses



### Page 20 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

### Table 10 : DDT and PCB Conc entrati ons in Lo w e r Okanog an Riv e r Sediment Core Collected Se ptember, 20 01 (ng/g, d w ) Dep t h Interv al

(cm ) Year Depo sited %T O C 4,4'- DDE 4,4'- DD D 4,4'- DDT tDDT PCB1260 PCB1254 PCB1248 t-PC B a

0

- 2 2 0 0 1 1

. 9 5 % 6

. 9 1. 9 u ( 0

. 6 3 ) 8

. 8 u(2.5) 0

. 8 9 u ( 2

. 5 ) 0

. 8 9

6

- 8 1 9 9 8 1

. 7 2 % 7

. 1 2. 2 u ( 0

. 5 3 ) 9

. 3 u(2.1) 0

. 7 4 u ( 2

. 1 ) 0

. 7 4

12-1 4 1 9 9 5 1

. 6 2 % 7

. 5 2

. 6 u ( 0

. 4 9 ) 1 0 u(2.0) 1

. 1 u ( 2

. 0 ) 1

. 1

18-2 0 1 9 9 2 1

. 4 8 % 6

. 8 2

. 5 u ( 0

. 4 5 ) 9

. 3 u(1. 8 ) 0

. 8 8 u ( 1

. 8 ) 0

. 8 8

24-2 6 1 9 8 8 1

. 4 0 % 8

. 0 3

. 0 u ( 0

. 4 4 ) 1 1 u(1.8) 1

. 1 u ( 1

. 8 ) 1

. 1

28-3 0 1 9 8 4 1

. 4 1 % 9

. 9 4

. 4 0. 6 5 1 5 0

. 4 4 1

. 5 u ( 1

. 7 ) 1

. 9 4

30-3 2 1 9 8 1 1

. 4 4 % 1 4 8

. 0 1. 1 2 3 0

. 7 4 2

. 1 u ( 1

. 7 ) 2

. 8 4

a Aroclors 1242, 1232, 1221 , and 1016 not d e tected at practical qu antitation limits of 1.7 – 2

. 5 ng/g u=undetected at practical qu an titation limit in par e ntheses



## Sedim e nts in the core from Osoyoos Lake dated from 1917 whereas the olde st horizons from the river m outh were deposited circa 1981, although the lack of background 210 

## Pb from the m outh leaves som e doubt about the accu racy of age estim a te s at this site. Sed i me ntation rates appear to be about three tim es higher near the mouth (1.6 cm /yr) com p ared to southern Osoyoos Lake (0.5

cm /yr).

DDT concentrations in the Osoyoos Lake core w e re an order of m a gnitude higher than sedim e nts of approximately equal age from the Okanoga n River m outh. Differences between these locations are probably due to dilution by relativel y clean sediments from the Sim ilka m een River which supplies the vast m a jority of sedim e nt s to the lower O k anogan River (Ehinger, 1994). Evidence in dicating the Sim ilkam een River prov ides a diluting influence com e s from data showing low ( ≤ 2 ng/g) to undetectable DDT concentratio ns and other chlori nated organics in Sim ilka m een River bottom sedim e nts (D. Hu rst, written communication; Johnson and Polotnikoff, 2000). Sim ilkam een River sedim e nts ha ve also been shown to contain very little organic carbon content which pr obably accounts for the lower TOC in sedim e nts from the Okanogan River m outh.

The reconstructed history of DDT contam in ation in Osoyoos Lake shows initial DDT concentratio ns barely d e tectab le or very low from 1917 until 1 945 (Figure 4), where its presence

m a y be due to lim ited mixing by burrowing organism s. DDT concentrations rose sharply after 1945, peaked around 1976, then declined sharply between 1976 and 1981. DDT concentrations show little c h ange durin g the subseq uent two dec a des.

A large spike in DDT concentrations was seen in sedim e nts deposited ar ound late 1998 or early 1999. Concentrations of t-DDT (250 ng/g) were triple those seen during the 1980s and 1990s (60-100 ng/g). This sample had a rem a rkably high concentration of 4,4’-DDT relative to 4,4’- DDE and 4,4’-DDD, constituting 39% of t-DDT. Other horizons had 4’4-DDT m a king up a

m a xi m u m of 15% t-DDT, but was generally 5% or less. The high proportion of 4,4’-DDT coupled with the anom alous concentration sugge sts the occurrence of a large disturbance and
Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 21

## subsequent input of agricultural so ils where DDT is degraded at a m u ch slower rate than in the aquatic environm ent (Harris et al., 2000). The presence of high levels of undegraded DDT could possibly hav e resulted f r o m a spill o r illegal dum ping during the la te 199 0s.

DDT concentrations at the Okanogan River m o uth show a decreasing trend in the 1980s followed by steady con c entrations d u ring th e la s t decade (Figure 4). Th e decline in DDT concentrations during the 1980s is most likely the tail end of a l onger and steeper decline, but the lim ited core depth only p e rm itted analysis back to 1981. The late 1990s sp ike seen in Osoyoos Lake DDT concentrations did not appear in the sedi m e nt core from the mouth. It is possible that it could have been m i ssed if this spike was a si ngularly discreet episode . Alterna tive l y, it m a y take several years for a contam inant pulse to tr avel from Osoyoos Lake sedim e nts to the m outh of the Okanogan River.

PCB concentrations in core sam p les were low, with concentrations generally around 1 ng/g tPCB (Figures 3 and 4). The pa tte rn of PCB concentra tions in both cores appeared to m i rror DDT concentrations, including a late 1990s spike in the Osoyoos Lake core. The peak PCB concentration was found in the 1976 horizon in Osoyoos Lake sedim e nts followed by a sharp decline 5 years later. No PCBs wer e detect ed in sedim e nts deposit ed in 1957 or earlier.

Unlike DDT concentrations which were m u ch higher in Osoyoos Lake sedim e nts, PCB concentrations were sim ilar in core sam p les fr om both locations. This m a y suggest that lowlevel PCB s ources such as STPs between the la ke and the river m outh keep depositional areas enriched with low levels of PCBs.



# 0 50 100 150 200 250 300

1915 1930 1945 1960 1975 1990 2005 Ye a rt-DDT(ng/g,dw)



# 0 5 10 15 20 25 30t-PCB(ng/g,dw) 

# DDT


# PC B

Figure 4: T-DDT a nd t-PCB Conc entr ations in Os o y oos Lake Sediment Co re



### Page 22 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# 0 5 10 15 20 25

1980 1985 1990 1995 2000 2005 Y

eart-DDT(ng/g,dw)



# 0 1 2 3 4 5t-PCB(ng/g,dw) 

## DD T
PC B

Figure 5: T-DDT a nd t-PCB co nce n tr ations in lo w e r Okan ogan Riv e r sediment cor e



## DDT and PCB Concentrations in Fish Tissue Carp, m ount ain whitefish, and sm allmouth bass were collected from three locations on the lower Okanogan River during 2001, except for carp whic h were not found at the Monse location. Sam p les at each location were so rted by size to as sess th is as a factor affecting contam inant

accum u latio n. Sam p les were analy z ed for DDT, PCBs, and lipid con t ent in fille t. Ta ble 11 shows the results.

Concentrations of t-DDT ranged from 30 to 600 ng/g, while t-PCB concentrations were m u ch lower, ranging from 2 ng/g or less to 40 ng/g. Mountain w h itefish and carp generally had m u ch higher DDT and PCB concentrations than sm allmouth bass.

4,4’-DDE was the prim ary DDT component, exce eding the N T R criterion of 32 ng/g in all

sam p les except sm allm o u th bass from the Rive rside-Om ak location. 4,4’-DDD conce n trations

were m u ch lower with o n ly one sam p le – Rivers ide-Om ak carp – exceed ing the NTR criterion of 45 ng/g. None of the samples exceeded the 4,4’-DDT criterion.

PCB-1254 m a de up the highest pro portion of t-PCB in m o st sam p les, followed by PCB-1260 and PCB-1248. PCB-1242 was not detected aside fro m a low concentration (4.0 ng/g) in one Riversid e-Om ak carp sample. All carp and m o untain whitefish m e t or exceeded th e NTR criterion for PCBs (5.3 ng/g). In contrast, onl y one of the nine sm all m outh bass sam p les had tPCB greater than the criterion.

Lipid content, size, and location all appear to be factors in DDT and PCB concentrations within each species. Figures 6 and 7 show lipid-no r m a lized t-DDT and t-PCB concentration s grouped by species f o r each location. Carp and m ountain whitefish collected at the Oroville location clearly had higher lipid-norm a lized t-DDT concentrations than fr om other sites. Sm allmouth

Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 23

## bass from M onse had lipid-norm a lized t-DDT concen tr ation s s lightly highe r than those colle cted from the Oroville and Riverside-Omak locations.

Lipid-norm a lized t-PCB concentr atio ns genera lly f o llowed the sam e location patte rn as with lipid -norm a lized t-DDT; the highe st c oncentr atio ns were at Oroville, followed in decreasing order by Riverside Om ak and Monse. However, carp from Oroville and Riverside-Omak had sim ilar concentrations, and th e lipid-norm a lized t-PCB concen tra tions in the larg e-s i ze d

sm all m outh bass from M onse were much higher than those from other locations.

In nearly all cases, th e largest f i sh co mposites (g r eates t m ean tota l leng th) had the high est t-DDT and t-PCB concentration s for each sp ecies at each site. Th is was generally the cas e in lipid

norm a lized concentrations as well. It should be noted that species were not sam p led by size class in order to com p are locati ons according to size. For inst ance, carp size classes are not necessarily a valid comparison be tween Oroville and Riverside-Om ak, since all composites from Riverside-Om ak had a larger or nearly equal av erage size than those from Om ak. Grouping by size was done to assess the relationship with cont am inant concentrations within each location.

Page 24 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily LoadLower Okanogan River Basin DDT and PCBsTotal Maximum Daily LoadPage25Page25Table 11: DDT and PCBConcentrations in Fillet ofFish fromthe Lower Okanogan River, 2001 (ng/g,ww)SampleNo. (02-)SpeciesLocationN PerComp.MeanLength(mm)MeanWeight(g)MeanAge(yr)Lipid(%)4,4'-DDE4,4'-DDD4,4'-DDTt-DDTPCB1248PCB-1254PCB-1260t-PCBa128230CARPOroville8552±252,135±432nc1.0429037u(1.6)3272.75.14.713128231““8514±71,749±93nc0.8441024u(1.5)4341.73.93.19128232““7463±371,348±354nc1.55210380.62493.64.22.210128233“Riv.-Omak8619±203,345±385nc3.4327041u(1.5)3116.89.21026128234/35““8584±122,740±481nc3.0022029u(1.6)24913101336128236““8550±132,393±320nc3.0921026u(1.6)236u(18)9.98.422b128237MTWFOroville8363±21315±7650.7946038175153.0128.724128238““8330±7229±5441.31330219.83612.99.87.320128245““8290±14167±2121.17150195.11742.46.13.212128239/40“Riv.-Omak10365±19453±8764.2652062175995.2191842128241““10334±13331±6954.7033039133823.0107.320128249““10284±20209±4834.58160196.01855.0187.030128242“Monse9326±48301±13442.96110143.21273.59.86.220128243““9246±7127±1823.07120163.71402.56.42.311128244““8220±1581±1421.55734.92.881u(2.8)2.92.15128246SMBSOroville14241,11153.2123044142883.98.12.615128247““4316±28472±138nc1.3964112.377u(2.7)2.4u(2.7)2128248““124820611.601003.50.8104u(2.8)2.2u(2.8)2128250“Riv.-Omak7350±56685±37741.17786.53.188u(2.7)2.7u(2.7)3128251““7287±11320±4731.42552.91.6605.62.1u(2.7)8128252““7213±28133±5010.95251.70.828u(2.8)u(2.8)u(2.8)nd128253“Monse5327±12496±4131.35150143.01672.99.51.914128254““5276±32276±9831.1289111.6102u(2.7)2.2u(2.7)2128255““5200±1098±1810.70593.40.863u(2.8)u(2.8)u(2.8)ndaAroclors 1268, 1262, 1242, 1232,1221, and 1016 not detected at practicalquantitation limitsof 2.7 – 5.4 ng/gbIncludes 4.0 ng/g PCB-1242MTWF=mountain whitefishSMBS=smallmouth bassnc=not calculatedu=undetected at practical quantitation limitin parenthesesnd=not detected0 10,000 20,000 30,000 40,000 50,000 60,000 70,000

L g Md S m Lg Md S m L g Md S m L g Md S m L g M d S m L g Md S m Lg Md S m Lg Md S mt-DDT(ng/g lipid)

CA RP O r ov ill e R iv -O m a k O rov i l l e R i v
- O m ak Monse O rov i l l e R i v -O m a k M ons e

M O UNT AIN W H I T E F ISH SM AL L M O U T H B ASS



### Figure 6: Li pid-No rmalized t-DDT Co ncen tratio ns in Lo w e r Ok anogan Riv e r Fish Muscl e Ordere d b y Mean Len g th of Fish i n each Composite ( Lg=l a rge, Md=m e d ium, Sm=small) and Lo cation for each Specie s

0 50 0 1, 0 0 0 1, 5 0 0 2, 0 0 0 2, 5 0 0 3, 0 0 0 3, 5 0 0

Lg M d S m Lg M d S m Lg M d S m Lg M d S m Lg M d S m Lg M d S m Lg M d S m Lg Mt-PCB(ng/g lipid)

O r o v ill e R iv

- O m a k O ro vil l e Ri v- O m ak M o n s e O r o v ille Riv- Om ak Mo d S m

CA RP n s e

M O UNT A I N W H IT E F IS H SM ALL M O U T H BASS



### Figure 7: Li pid-No rmalized t-P CB Co ncen tratio ns in Lo w e r Ok anogan Riv e r Fish Muscl e Ordere d b y Mean Len g th of Fish i n Each Com posite ( Lg=l a rge, Md=m e d ium, Sm=small) and Lo cation for each Specie s



### Page 26 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Loadi ng Capacity

The following sections contain a TMDL analys is of DDT a nd PCBs in the lower Okanogan River basin using the data collected during 2001-2002, or in som e cases historical data (Appendix A) to describe or quantify DDT and PCB loading to the lower Okanogan River and Osoyoos Lake.



# Daily DDT and PCB Loads to the Lower Okanogan River and Osoyoos Lake

DDT Loads Delivered Through Tributary Stream s Loads were calcu lated u s i ng the following equation:

Load (mg/day) = C w 

## x (10 -6 

## mg/ng) x Q x (86,400 s/day)

Where:

• C w 

## (concentration in water) = con cen tr ation of DDT or PCBs in water (ng/l)

• Q (discharge) = instantaneous flow , unless stated otherwise (l/s)

DDT loads in tributaries were m easured during a total of four rounds of sampling conducted during 1995 and 2001 (Table 12). As m e ntioned previously, sam p ling during 1995 represented low-flow conditions, w i th m a ny stream channels dry and others (e.g. Tallant Creek) flowing due only to release of stored ir rigation water (T. Neslen, OCCD , personal communication). To account for the interm ittent flow (and resultant lo ad ing) in so m e stream s, weighted mean loads were calcula ted for each stream by multip lying th e m ean loads by the perc entage of tim e s the
stream was found flowing during sampling visits. The following for m ula describes calculation of the weighted m ean load for each tributary:

Weighted Mean Load = (sum of n loads/n) x (n/number of sample attempts)

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 27

### Table 12 : Weighted M e a n DDT Lo ad s in Tributar y Streams of Oso y oos Lake and th e L o w e r Okano g an Riv e r Based o n Water Col u mn Samples Collected 1995 -20 02 (mg/da y )

Loca t ion RM Samples/ At tem p t s 4,4'-DDE 4,4’-DDD 4,4’-DDT t- DDT Okanog an R. @ Osoy oos, BC 9 1

. 2 1 / 1 0

. 0 0

. 0 0

. 0 0

. 0

Ha yn es Creek (BC) 82. 8 1 / 1 1

. 3 0

. 0 0

. 0 1

. 3

Nine Mi le Cr ee k 80.2 4 / 4 6

. 6 2

. 1 4

. 9 1 3

. 6

T onasket Cree k 77.8 2/ 4 1 2

. 4 0

. 0 8

. 4 2 0

. 8

Similkam ee n R i ver 74.1 2 / 2 0

. 0 0

. 0 0

. 0 0

. 0

Mosqu i to Cree k 67.4 3 / 4 1

. 0 1

. 0 0

. 0 2

. 0

W h itestone Cr eek 62.4 4 / 4 6

. 7 0

. 0 0

. 0 6

. 7

Antoin e Cre e k 61.2 4/ 4 4

. 8 0

. 6 1

. 0 6

. 4

Si w a s h Creek 57.3 1/ 4 0

. 3 0

. 0 0

. 0 0

. 3

Bona parte Cr e e k 56.7 3 / 4 1

. 9 0

. 0 0

. 0 1

. 9

Aene as Cre e k 52.9 3/ 4 1

. 5 0

. 0 0

. 0 1

. 5

Che w i lik en Cr e e k 50.7 1 / 2 0

. 0 0

. 0 0

. 0 0

. 0

T unk Creek 45.0 2/ 4 0

. 0 0

. 0 0

. 0 0

. 0

Johns on Cre e k 40.6 2/ 4 0

. 0 0

. 0 0

. 0 0

. 0

W anacut Cre e k 35.0 2/ 4 0

. 0 0

. 0 0

. 0 0

. 0

Omak Creek 32.0 3/ 4 0

. 0 0

. 0 0

. 0 0

. 0

Elgi n Creek 28.4 4/ 4 1 4

. 4 0

. 6 7

. 1 2 2

. 0

Salmo n Creek 25.7 1/ 4 2

. 5 0

. 0 0

. 0 2

. 5

T a llant Creek 19.5 2/ 4 4 6

. 6 1 0

. 5 6 8

. 6 1 2 5

. 7

Lou p Lo up Cre e k 16.9 2/4 t r a c e 0

. 0 t r a c e 0

. 1

Chil i w ist Cre e k 15.1 2 / 4 0

. 6 0

. 0 0

. 0 0

. 6

T o t a l = 1 0 0

. 4 1 4

. 7 9 0

. 1 2 0 5

. 2

trac e = <0 .05 m g /da y



## The t-DDT load from all tributaries com b in ed average 205 m g /day, with 4,4’-DDE and 4,4’- DDT com p r i sing the bulk (93%) of the t-DDT load. Most of the DDT load delivered to the lower Okanogan River through tributary stream s is from Tallant Creek (61% of t-DDT ), even though this stream was found to be flowing during onl y two of four attempts to sam p le it. Flow in Tallant Cr eek is lim ited to a f e w months per ye ar when water is released from Leader Lake for irrigation. T h erefore, DDT loads from Talla nt Creek are probably best described as

com p aratively large, episodic, and difficu lt to accurately quantif y without intensive investigation.

Page 28 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

### Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load Page 29 

## Ninemile, Tonasket, and Elgin Creeks together ac count for a large remainder of the DDT loads from tributaries (27% of t-DDT). Ninemile a nd Elgin Creeks were among the four streams to have measurable DDT loads during all 1995 and 2001 sampling events. Whitestone and Antoine Creeks also had measurable DDT lo ads during all rounds of sampling.

Mean DDT loads were higher during 1995 compared to 2001 (307 mg t-DDT /day vs. 104 mg tDDT/day, respectively) due primarily to the Tallant Creek samples collected during 1995. However, mean loads were similar between year s when the contribution from Tallant Creek is removed (55 mg t-DDT /day in 1995; 104 mg t-DDT/day in 2001).

Notable is the absence of any DDT load from th e Similkameen River, which has the potential to deliver large loads due to its high flow. For in stance, had 4,4’-DDE been detected at the very low practical quantitation limit (0.07 ng/l) duri ng 2002 sampling, the resulting daily load (660 mg/day) would have been an order of magnitude higher than the average daily loads of all other tributaries combined during 2001.

DDT and PCB Loads Delivered Through STPs Daily DDT and PCB loads from the Oroville, Omak, and Okanogan STPs are shown in Table 13. Loads were calculated from ef fluent sampling conducted during April and May 2001, and in May, 2002.

Table 13: Mean DDT and PCB Loads in Lower Okanogan River Basin STPs Based on Whole Effluent Samples (DDT) and PCB Concentrations in STP Sludge Collected 2001-2002 (mg/day)

Location RM n 4,4'- DDE 4,4’-DDD 4,4’-DDT t-DDT t-PCB a
Oroville STP b 3 0. 1 0.0 0.4 0.5 0.1
Omak STP 29.9 3 0. 0 0.0 0.0 0.0 1.3 Okanogan STP 24.8 3 0. 8 0.3 1.1 2.2 1.3

a Results shown are for PCB Aroclors 1260, 1254, 1248, 1242, 1232, 1221, and 1016

b Similkameen River mile 4.0. The Similkameen River ente rs at Okanogan River mile 74.1



## Daily loads of DDT and PCBs were low at a ll three STPs sampled. Oroville and Okanogan STPs had daily DDT loads similar to the lowest measured loads in tributary streams. Daily loads in effluent were 2.7 mg t-DDT/day and 0.4 mg t-PCB/day from all three STPs combined.

As shown previously, PCBs were present at subs tantial concentrations in sludge from all three treatment plants (200-270 ng/g t-PCB, dw). Si nce PCBs were difficult to detect in water, estimates can be made of PCBs discharged from STPs in the form of suspended particulate matter in effluent. Assuming the suspended solids in effluent are composed primarily of sludge, the estimated t-PCB load from STPs combined is approximately 2.7 mg/day using the following formula:

mg PCB/day = mg PCB/kg sludge x (mg sludge/l effluent x [kg/10 6 

## mg]) x l effluent/day

Using sludge concentrations to estimate DDT load s yields an average combined t-DDT load of1.7 mg/day, similar to the combined load measured from whole effluent samples (2.7 mg tDDT/day).

### Page 30 Lower Okanogan River Basin DDT and PCBs Total Maximum Daily Load 

## Calculation of DDT and PCB Loads and Loadin g Capacities of Osoyoos Lake and the Lower Okanogan River
Loads measured and delivered to the lower main stem Okanogan River, theoretical loads based on tissue concentrations, and the lower Okanogan River’s capacity to assimilate DDT and PCBs are presented in this section and Table 14.

Delivered loads are the weighted mean loads from tri butary streams and STPs (12 and 13) and combined for each Okanogan River reach.

Measured loads in the lower mainstem Okanogan Rive r were calculated from DDT and PCB concentrations analyzed during May, 2002 (Table 5) and daily flows recorded at USGS gaging stations at Oroville, near Tonasket, and at Malott.

Theoretical loads in this report represent the all the a quatic environmental impacts on fish tissue contaminant levels. This aquatic environment impact includes contaminant exposures from water, sediments and the food chain in th e Okanogan River as a water contamination concentration that would reasonabl y be expected to result in fish tissue contamination that has been observed in the most recent Okanogan Rive r fish tissue samples. Theoretical loads were determined using DDT and PCB concentrations in fish tissue back-calculated to water concentrations using BCFs for each chemical. The most contaminated species from each reach was used to calculate theoretical loads (mount ain whitefish for lower Okanogan River reaches [Table 11], lake whitefish for Osoyoos Lake [Appendix A]).

Loading capacities were calculated using NTR human h ealth criteria and Ch. 173-201A WAC chronic aquatic life criteria (Table 1). Flows used to calculate loading capacities were harmonic means recorded at USGS gaging stations (Table 2).

DDT loads delivered through tributaries and STPs were generally one to three orders of magnitude below the measured loads, theoretical lo ads, and the loading capa cities of each reach indicating that exogenous DDT input accounts for onl y a minor amount of the load in the lower mainstem Okanogan River and Osoyoos Lake.

Since no PCBs were detected in lower Okanoga n River water it is not feasible to compare delivered loads to measured loads. Like DDT, how ever, delivered PCBs appear to be orders of magnitude below theoretical loads and loading capacities in all reaches except Osoyoos Lake where PCBs were undetectable in edible fish tissue.

PCBs loads consisted of a trace amount (0.1 mg t-PCB/day) from the Oroville STP, representing about 0.01% of the loading capaci ty of the Okanogan River near Tonasket based on the State criterion. The combined t-PCB loads from the Omak and Okanogan STPs (2.6 mg t-PCB/day) was about 0.3% of the loading capacit y of the Okanogan River at Malott.

### Table 14 : Total Load Deliv er y , Measur e d Loads, T h eore tical L o ads, and L o ading Ca pa cities of DDT and PCBs a t Sev e ral Oso y oos Lake an d Lo w e r Ok ano g an Riv e r Reaches (mg/d a y )
Rea c h RM 4,4'-DDE 4,4’-DDD 4,4’-DDT t- DDT t-PC B Os oy oos La ke ; RM 9 1

. 2

- 7 9 .0
T o tal load de liv ered to reac h (tribs.) 91.2 – 8 0 .2 8 2 5 15 0

T heoretical Lo ad (US W a ters ) 82. 5 – 7 9 .0 17,00 0 10,00 0 770 25,00 0 0

Loa din g cap. @ Oso y . Lk. o u t l e t 7 9

. 0 8 0 0 1

, 1 0 0 8 0 0 1

, 4 0 0 2 3 0

Near Oro v ille; RM 79-77.4
T o tal load de liv ered to reac h (tribs.) 77.8 12 0 8 21 0
Cumul a tive l o a d 77.8 12 0 8 21 0

Measur ed lo ad @ Oroville 77.4 660 830 0 1,500 0

T heoretical Lo ad 77.3 – 7 6

. 4 7

, 8 0 0 6 5 0 2 8 0 8

, 7 0 0 820 a

Loa din g cap a ci t y @ ne ar Oroville 74.1 800 1,100 800 1,400 230

Nea r T o n aske t; RM 77.4-50. 7
T o tal load de liv ered to reac h (tribs. and ST Ps) 74.1 – 5 2 .9 16 2 1 19 trace b

Cumul a tive l o a d 77.4 – 5 2 .9 680 830 1 1,500 trace b

Measur ed lo ad @ Riversid e 4 0

. 6 2

, 6 0 0 1

, 7 0 0 0 4

, 3 0 0 0

T heoretical Lo ad 41.0 – 3 0 .7 4 1

, 0 0 0 4

, 9 0 0 1, 5 0 0 4 5

, 0 0 0 6,500 a

Loa din g cap a ci t y ne ar. T ona s k e t 5 0

. 7 3

, 9 0 0 5, 5 0 0 3

, 9 0 0 6

, 5 0 0 1

, 1 0 0

Near Malott; RM 50.7-17.0
T o tal load de liv ered to reac h (tribs. and ST Ps) 50.7 – 1 9 .5 64 11 77 152 3 b

Cumul a tive l o a d 50.7 – 1 9 .5 2,700 1,700 77 4,500 3 b

Measur ed lo ad @ Malott 17.0 2,200 2,000 0 4,200 0

T heoretical Lo ad 10.5-4.9 13,00 0 1

, 5 0 0 4 0 0 13,00 0 2,600 a

Loa din g cap a ci t y @ Malott 1 7

. 0 4

, 0 0 0 5

, 6 0 0 4

, 0 0 0 6

, 7 0 0 1

, 1 0 0

Mo u t h ; RM 16.0-0.0
T o tal load de liv ered to reac h (tribs.) 16.9 – 1 5 .1 1 0 0 1 0
Cumul a tive l o a d 17.0 – 1 5 .1 2,200 2,000 0 4,200 0

T heoretical Lo ad 10.5-4.9 13,00 0 1

, 5 0 0 4 0 0 13,00 0 2,600 a

Loa din g cap. @ Okan. R. m o u t h 0

. 0 4

, 0 0 0 5, 6 0 0 4

, 0 0 0 6

, 7 0 0 1

, 1 0 0

trac e = <0 .5 m g / d a y

a Results shown are for PCB Aroclors 1268, 1262, 1260, 1254 , 124 8, 1242 , 1232 , 1 221, and 1016

b Results shown are fo r PCB Aro c lors 1260, 1254 , 1248 , 1242 , 12 32, 1221 , and 10 16



## Using W a shington State and NTR DDT criterion, the m easured loads in the lower Okanogan River did no t exceed loading capacities except fo r t-DDT in the Oroville reach where it was 15% above the loading capacity. Measured loads of 4,4’-DDE, 4,4’-DDD, and 4,4’-DDT were below the load ing capacities at Oroville when the NTR criteria were us ed to ca lc ulate the lo a d ing capacities of these com pounds.

Although measured loads of DDT sh own in Table 14 represent the only instance when accurate instantaneous load assessm e nts have been avai lable for the lower m a instem Okanoga n River, these loads m a y actually overe stimate annual average DDT lo ads in the water column.

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 31

## Measured lo ads were ca lculated during high-f l o w condition s in May wh en TSS concentra tions are typically at or near their a nnual peak, suggesting that DDT (w hich sorbs to particulate m a tter)

m a y also be at its highest concentration. A pot entially m o re accurate m easurem ent of average annual loads could be obtained from tissues in fi sh, which integrate concentrations over tim e and
space.

Theoretical loads of DDT and PCBs were m u ch hi gher than m easured loads in all reaches of the lower Okanogan River, with the exception of 4,4’-DDD at Oroville where the theoretical and

m easured loads were sim ilar. The com p aratively high theo retical lo ads (derived fro m tissue concentratio ns) indicate that the relationship with m eas ured lo ads (derived from water colum n concentratio ns) is incons isten t with the BCFs us ed to link tissue and water concentrations. The BCFs for both DDT and PCBs appear to overestim ate the theoretical water concen trations th at should lead to certain co ncentrations in tissue.


# Source Assessment

Historical D D T use in the Okanogan Basin, prim arily on orchard and ot her agricultural lands, has resulted in contam ination of the aquatic environm ent. A lthough banned in the U.S. as a pesticide in 1972, DDT and its b r eak down produc ts have p e rsisted, accu mulating at high concentrations in lower Okanogan River and Oso yoos Lake fish as shown in this and other investigations (e.g. Johnson and Norton, 1990; Davis and Serdar, 1996; S e rdar et al., 1998).

PCBs are a ubiquitous environm ental contam inan t and, like DDT, they have persisted in the aquatic environm ent and continue to accum u late in fish tissue even t hough production of PCBs was banned 25 years ago. However, due to the difficulty in detecting PCBs in the water colum n, little effort has been m a de to track down the source(s) of PCBs in the lower Okanogan River system

.

It is no tab l e that while P CBs in edible f i sh ti ssues m a y be a hum an health concern at the levels reported here (2 – 42 ng/g); it is not uncommon to find sim ilar levels in other W a shington waters where no discernible sources of PCB exist (D avis and Johnson, 1994; Davis et al., 1998). Conversely, waterbodies with know n point sources of PCBs s u ch as the S pokane River have PCB concentrations in fish one to tw o orders of m a gnitude higher than those found in the lower Okanogan River (E cology, 1995).

The source of DDT delivered to tributaries has not been exam ined. Presum ably, DDT bound to agricu ltu ral soils m a kes its way to s t ream s direct ly or through rivulets form ed during rainstorm s , snowm e lt, or irrigation. Due to the low solubi lity of DDT compounds in water, the mechanism of delivery probably involves pa r t icle transpo r t r a ther than leaching and dissolution of DDT.

Transport of agricu ltu ral soil pa rticle s to str eam s depends on a variety of factors. W ithin
stream s, increasing flows result in h i g h er T SS concentration s . For stream s where DDT was detected during all four rounds of sampling, fl ows were a major positive determ inant of TSS concentrations in Ninemile Creek (r 2 

## = 0.89), Antoine Creek (r 2 

## = 0.89) and Elgin Creek (r 2 

## = 0.94) but less so in W h itestone Creek (r 2 

## = 0.27). However, higher concentrations of DDT

com pounds were not a f unction of higher TSS con centrations, and in some cases (Ninem ile and

Page 32 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

## Elgin) show ed a negative relationship with TSS. Only W h itestone Creek showed DDT concentrations highly de pendent on TSS (t-DDT; r 2 

## = 0.97).

Differences in TSS levels am ong tributaries ac count for about 25-40% of the variation in concentrations and loads of DDT based on an anal ysis of pooled tributary data. However, the regression used to explain this relationship is leveraged largely by data from Tallant Creek with high TSS (122 m g /l) and exceptionally high DDT ( 0.5 μg t-D D T/l). Absent the Tallant Creek data, TSS does little to explain DDT concentrations.

The lack of a strong functional relationship betw een TSS and DDT concentrations suggests suspended s o lids in the water co lumns of tributa r ie s are larg ely com posed of particles other than
contam inated soils. In general, orchards and other agricultural lands in the lower Okanogan River Basin are on shallow slopes, soils are well-drained, grass is m a intained as ground cover in orchards, an d irrigation is sprink ler o r drip rath er than rill and furrow. These condition s do not lend them selves to subs ta ntia l eros ion of agricultu r al so ils as o c curs, f o r in stance, in th e lower Yakim a River Basin where TSS and DDT are highl y correlated in tributaries (Johnson et al., 1988; Joy and Patterson, 1997).

During the initial investigation of DDT in Oka nogan basin stream s, GIS covers were used to overlay DDT concentrations on the amount of steep slopes and percentage of orchard lands in each tributary basin. Although this was conduc ted only on a cursory basis, these factors appeared to correlate poorly with D D T concentr ations in stream s (A. Johnson, Ecology, personal communication).

In urban areas, STPs m a y serve as a funnel fo r waterborne contam inants. The wastewater system could potentially deliver contam inants su ch as DDT that were used historically for nonagricu ltu ral purposes su ch as m o squito con t rol a nd carried off soil via stor mwater to STPs. DDT and PCBs could also potentially end up in STPs as a result of im proper storage and disposal.

Other possible DDT and PCB sources and delive ry m echanism s that were not revealed by

sam p ling may include groundwater, deposition of airborne m a teri al, illegal dum ping, and erosion of contam inated bank m a terial. It is also poss i ble that the s t ream s sam p l e d deliv er large DDT and PCB loads that were not captured duri ng sam p ling, and therefore tributary sam p ling conducted during 1995 and 2001 was not representative. Another possibility is that sm all nearbank drainages went unnoticed during tributary sam p ling.

These sources and delivery m echanism s probabl y contribute unaccounted quantities of DDT and PCBs to som e extent. However, if the conti nual delivery of significan t DDT quantities to the lower Okanogan River and Osoyoos Lake through one or m o re of these m echanis m s results in
water co lumn concentrations com p arable to fish tissue concentrations (using a BCF conversion), then the water colum n concentrations s hould be present at higher concentrations.

In consideration of the factors previously m e ntioned, it is unlikely th at significant exogenous sources of DDT and PCBs have gone unaccounte d. There are essentially two scenarios to explain DDT and PCB accum u latio n in fish tiss ues. The first explanatio n is that the BCF used to calculate the NTR water criter ia for DDT and PCBs are inaccurate. These BCFs (53,600 for DDT and 31,200 for PCBs) were derived specifica lly for criteria developm ent, not for siteLower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 33

## specific assessm ent. It is possible that at least som e species in the lower Okanogan River concentrate DDT and PCBs by fact ors one to two orders of m a gn itude higher than the criteria BCF.

A higher BCF for DDT i n fish m a kes it possible to explain h i gh tissue co ncentr ation s rela tive to water. For the present DDT listings in the lower Okanogan River and Osoyoos Lake, BCFs ranging from 66,000 to 2,800,000 would explain repor ted tissue concentrations at DDT concentratio ns in water. These BCFs are not unreasonable considering E P A cites seven

exam ples of field-m easured BCFs for DDT in freshwater fish (whole body) greater than one

m illion (Ambient W a ter Quality Cr iteria f o r DDT ; EPA, 1980a). BCFs are gene rally lower f o r muscle than whole body, but EPA (1980a) list s B C Fs of 460,000 and 370,000 for lake trout ( Salvelinus namaycush ) and cisco ( Coregonus sp.) m u scle, respectively. E P A reports a narrower range freshwater fish BCFs for PCBs in their criteria developm ent docum ent for PCBs (EPA, 1980b), with a m a xi m u m whole body BCFs of 270,000 ( Pimephales prom elas ; Aroclors 1242 and 1260) and m u scle BCFs less than 10,000 ( Salvelinus fontinalis and Oncorhynchus mykiss [for m erl y Salmo gairdneri ]).

The second plausible explanation for high DDT a nd PCBs in fish relative to water colum n concentrations is that the exposure route is som e th ing other than water. S p ecifically, fish m a y be

accum u latin g DDT and PCBs through contam inated se d i m e nts or diet. The lack of significan t exogenous DDT sources com b ined with high fish tissue concentrations suggests that the bed sedim e nts are the prim ary route of exposure in lower Okanogan River and Osoyoos Lake fish.

It is not unreasonable to assum e that re-sus pended Osoyoos Lake sedim e nts account for nearly all of the m easured DDT loads in the lower Ok anogan River. Osoyoos Lake bed sedim e nts resuspended d u ring high flows, spring turnover, o r other pertu r bations m a y account for the disparity between DDT l o ad delivery and m easur ed loads in the water co lum n of the lower

m a inste m Okanogan River. These differences ca n be explained by assuming suspended solids in the water colum n are composed of re-suspe nded surficial (top 2-cm ) Osoyoos Lake bed sedim e nts. Table 15 compares m e a s ured loads with loads calculated by assum i ng TSS at the Osoyoos Lake outlet is com posed of the sam e m a terial as the top 2-cm of the Osoyoos Lake sedim e nt core. Loads from re-suspended Osoyoos Lake bed sedim e nts match well with the

m easured DDT loads at Riverside and Malott, although m easured loads at Oroville should be approxim a tely 150% higher. Relative concentrati ons of DDT com pounds in m e asured loads (i.e. 4,4’-DDE ≈ 4,4’-DDD >> 4,4’-DDT) are sim ilar to c oncentrations in Osoyoos Lake bed sedim e nt, further indicating that m e a s ured load s m a y originate from sedim e nt re-suspension.

CCT conducted a longitudinal transect of DDT in 40 lower Okanogan River sedim e nts from the Osoyoos Lake outlet to the m outh during 2001 (H urst and Stone, 2002; D. Hurst, written communication). Aside from two locations, little DDT was found. Sixty percent of the sites had DDT (t-DDT) less than the det ection lim it (0.5 ng/g) and anothe r 35% had concentration 1-10 ng/g (m ostly less than 2 ng/g). The only signifi cant DDT levels were found just below the Osoyoos Lake outlet (but upstream of Zoesel Dam ) at 46 ng/g t-DDT and just downstream of Elgin Creek (260 ng/g t-DDT). The site upstream of Zoesel Da m probably collects much of the

sam e settlin g particulate m a terial as southern Os oyoos Lake since it is within th e im pounded reach of the river (althou gh techni cally not part o f Osoyoos Lake).

Page 34 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

## The reason f o r the high DDT in sedim e nts downs tream of Elgin Creek is not certain, although this stream has chronically high DDT concentratio ns and m ode rate TSS levels. The Elgin Creek site m a y also be one of the few locations in th e lower m a instem Okanogan River where very fine

m a terial is a b le to a ccumulate. Visua l inspe c ti on reveals only a few large areas of fine sedim e nt deposits in the m a instem river, an observat ion shared by investigat ors conducting the CCT
survey.

Table 15 : Measur e d Loa ds of DDT a nd PCBs at Se v e ral Lo w e r Okan ogan Riv e r Reach es Compar ed to Loads Esti mated fr om Re-susp e ns i on of Surfici a l Oso y oos Lake Bed Se diments (mg/da y )

Rea c h RM 4,4'- DDE 4,4’- DD D 4,4’- DDT t-PC B a 

### t- DDT

Measur ed lo ad @ Oroville 77.4 660 830 0 1,500 0
Measur ed lo ad @ Riversid e 4 0

. 6 2

, 6 0 0 1

, 7 0 0 0 4

, 3 0 0 0
Measur ed lo ad @ Malott 17.0 2,200 2,000 0 4,200 0

Loa ds calc ulat ed from re-sus pens ion of surficial (top 2-cm ) Oso y o o s Lk. bed se dime nts 1,700 2,200 100 4,000 30

a Results shown are fo r PCB Aro c lors 1260, 1254 , 1248 , 1242 , 12 32, 1221 , and 10 16


# Load and Wasteload All o cations

DDT and PCB Load Al locati ons in Tributary Stream s DDT and PCB load allocations (LAs) for tributar y stream s are shown in Table 16. L A s were set at load ing capacities. Fo r tri butaries with weighted m ean load s below loading capacities, LAs were set at current loading levels. Since DDT and PCBs are persistent bioaccum ulative chem icals and have not been found at acutely toxic con centrations in the pr esent study, LAs for tributary stream s m a y be set at m onthly or even yearly averages, but are expressed as daily loads for consistency within this report.

Setting LAs for the Okanogan River at Osoyoos, B.C. and the Sim ilka m een River was more difficult since no DDT or PCBs have been detected at either location, yet th ey potentially deliver substantial DDT/PCB loads even while concentrations rem a in unde tectable. Major differences in laboratory quantitation lim its between sam p ling conducted during 1995 and later in 2002

m a de a logical appro ach to LAs even m o re difficult.

LAs for the Okanogan River at Osoyoos, B.C. (where the river enters Oso yoos Lake) were set at loading capacities for th is location. Setting LAs for the Okanogan River at Osoyoos, B.C. is more practical than settin g LA s farther downstream in m i d-la ke at the Canadian border.

For the Sim ilkam een River, LAs were set at av erage loads calculated fro m flows and one-half the practical quantitation lim its during sam p li ng in 1995 and 2002. Although this m a y initially

seem an arbitrary approach, LAs are well with in the loading capacities of the Sim ilkameen River and account reasonably well for th e increased D D T loads measured in the lower Okanogan River downstream of the Sim ilkam een River confluence. (see Table 14).

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 35

## The following stream s would require load reducti ons in order to m eet LAs; Haynes Creek (4,4’- DDE, t-DDT), Ninem ile Creek (4,4’-DDE, 4,4’- DDT, t-DDT), Tonasket Creek (4,4’-DDE, 4,4’- DDT, t-DDT), Mosquito Creek (4,4’-DDE, 4,4’- DDD, t-DDT), W h itestone Creek (4,4’-DDE), Antoine Creek (4,4’-DD E , t-DDT), Elgin Creek (4,4’-DDE, 4,4’-DDT, t-DDT), and Tallant Creek (4,4’-DDE, 4,4’-DDD, 4,4’-DDT, t-DDT).

Table 16 : DDT and PCB Load Alloca tions fo r Indiv i dual Tributar y streams (mg/da y )

Strea m /Rea ch RM 4,4'-DDE 4,4'-DDD 4,4'-DDT t-DDT t-PCB

Os oy oos La ke ; RM 9 1

. 2

- 80 .2 Okanog an R i ver @ Oso y o o s BC 91. 2 7 9 6

. 3 113 3

. 8 796. 3 1 3 4 9

. 7 2 2 9

. 5

Ha yn es Creek BC 82.8 0

. 3 0

. 0 0

. 0 0

. 5 0

. 1

Ninem ile Cr ee k 80.2 2. 0 2

. 1 2

. 0 3

. 4 0

. 6
Sum = 798.6 113 5. 9 7 9 8

. 3 135 3

. 6 2 3 0

. 2

Near Oro v ille; RM79-77.4
T onasket Cree k 77.8 4. 9 0

. 0 4

. 9 8

. 4 1

. 4
S u m = 4

. 9 0

. 0 4

. 9 8

. 4 1

. 4

Nea r T o n aske t; RM 77.4-50. 7 Similkam ee n R i ver 74.1 998. 7 9 9 8

. 7 102 8

. 1 302 5

. 6 7 9 1

. 0 Mosqu i to Cree k 67.4 0

. 4 0

. 5 0

. 0 0

. 6 0

. 1

W h itestone Cr eek 62.4 5

. 9 0

. 0 0

. 0 6

. 7 1

. 7

Antoin e Cre e k 61.2 1. 9 0

. 6 1

. 0 3

. 3 0

. 6
Si w a s h Creek 57.3 0. 3 0

. 0 0

. 0 0

. 3 0

. 1

Bona parte Cr e e k 56.7 1

. 9 0

. 0 0

. 0 1

. 9 0

. 8

Aene as Cre e k 52.9 1. 5 0

. 0 0

. 0 1

. 5 0

. 8
Che w i lik en Cr e e k 50.7 0

. 0 0

. 0 0

. 0 0

. 0 0

. 1
Sum = 101 0.6 999.8 102 9

. 1 3 0 3 9

. 9 7 9 5

. 2

Near Malott; RM 50.7-17.0
T unk Creek 45.0 0. 0 0

. 0 0

. 0 0

. 0 1

. 1

Johns on Cre e k 40.6 0. 0 0

. 0 0

. 0 0

. 0 0

. 4

W anacut Cre e k 35.0 0. 0 0

. 0 0

. 0 0

. 0 0

. 2
Omak Creek 32.0 0. 0 0

. 0 0

. 0 0

. 0 4

. 3 Elgi n Creek 28.4 1. 8 0

. 6 1

. 8 3

. 1 0

. 5
Salmo n Creek 25.7 2. 5 0

. 0 0

. 0 2

. 5 1

. 0

T a llant Creek 19.5 0. 2 0

. 3 0

. 2 0

. 4 0

. 1
S u m = 4

. 5 0

. 9 2

. 0 6

. 0 7

. 6

Mo u t h ; RM 17.0-0.0
Lou p Lo up Cre e k 16.9 0. 0 0

. 0 0

. 0 0

. 1 0

. 1
Chil i w ist Cre e k 15.1 0

. 6 0

. 0 0

. 0 0

. 6 0

. 4
S u m = 0

. 6 0

. 0 0

. 0

. 0 7

. 0 5



### Page 36 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

## DDT and PCB W a ste Load Allocations in STPs DDT and PCB waste load allocations (W LAs) for STPs are in Table 17. W L As were determ ined from design criteria flows and criteria concen trations for DDT and PCBs. Like the L A s for tribu t ar ies, W L As are expressed a s daily loads for consistency but m a y be set as m onthly or yearly averages.

Table 17 : DDT and PCB Was t e Lo ad Allocation s for STPs (mg/da y )
STP RM Design Flo w (l/s) 4,4'-DDE 4,4'-DDD 4,4’-DDT t- DDT t-PC B
Oroville a e 2 1

. 6 1

. 1 1

. 6 1

. 1 1

. 9 0

. 3
T onasket d 5 6

. 4 1 7

. 5 0

. 9 1. 3 0

. 9 1

. 5 0

. 5
Omak b 2 9

. 9 8 2

. 8 4

. 2 6. 0 4

. 2 7

. 2 1

. 2 Okanog an c 2 4

. 8 2 3

. 7 1

. 2 1. 7 1

. 2 2

. 0 0

. 3
C r i t e r i a (n g / l ) = 0

. 5 9 0

. 8 3 0

. 5 9 1

. 0 0

. 1 7

a NPDES permit WA-002239-0

b NPDES permit WA-002094-0

c NPDES permit WA-002236-0

d NPDES permit WA-005233-7

e Similkameen River mile 4.0

. Th e Similkameen River ente rs at O k anogan R i ver mile 74.1



## Daily loads m easured during 2001-2002 (Table 13) ar e generally consistent or lower than W L As. Exceptions are sm all ex ceedances o f t-PCB at Om ak and Okanogan STPs, and t-DDT at the Okanogan STP. It is not known if the potential di scharge of contam inants is within the Tonasket WLA. The current discharge for the city of Tona sket has not been sam p led due to the Tonasket WWTP beginning its discharge to th e rive r after the sam p les were taken f o r the cu rren t TMDL

assessm ent report.

DDT and PCB Load Al locations for Sedim e nts Table 18 shows DDT and PCB load allocations for exogenous sources (t ributary stream s and STPs), bottom sedim e nts, and loading capaci ties of successive Osoyoos Lake and low e r Okanogan River reaches. LAs for bottom sedim e nt s were calculated as th e difference between the cum u lative LAs/ W L As and the loading capacity of each reach.

LAs for the Okanogan River at Osoyoos, B.C. constitu te all o f the loading capacities at Osoyoos Lake and the Okanogan River at Oroville. The added loading capacity of the Sim ilkam een River provides for bottom sedim e nt DDT LAs of about one-half the loading capacities at reaches below Oroville. Howeve r, little cap a c ity is ava ilable for bottom sedim e nt PCB LAs at any of the reaches. This is due to the relativ e u n certainty regarding PCBs in the Sim ilkam een River which in turn is a f unction of the relatively high practical quantitation lim its for PCBs. A gr eater degree of certainty that PCBs were much lower in the Sim i lkam een River would ad d capacity for a PCB LA i n bottom sedim e nts.

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 37

### Table 18 : DDT and PCB Load Alloca ti ons for Bo ttom Sediments (mg/day )

Rea c h RM 4,4'-DDE 4,4'-DDD 4,4'-DDT t- DDT t-PC B
Os oy oos La ke Cumul a tive LA s (tribs.) 91.2- 8 0

. 2 7 9 8

. 6 113 5

. 9 7 9 8

. 3 1 3 5 3

. 6 2 3 0

. 2

Bottom sedime nts 82.5-7 9 .0 0 -12.4 0.3 0 0

Loa din g cap a ci t y 79.0 798. 6 1 1 2 3

. 5 7 9 8

. 6 135 3

. 6 2 3 0

. 1

Near Oro v ille Cumul a tive LA s/W L As (tribs.and ST Ps ) 9 1

. 2

- 7 7

. 8 8 0 3

. 5 113 5

. 9 8 0 3

. 2 136 2

. 0 2 3 1

. 6

Bottom sedime nts 79.0-7 7 .4 0

. 2

- 5

. 3 0

. 4 0

. 2 0

. 0

Loa din g cap a ci t y 77.4 803. 7 1 1 3 0

. 6 8 0 3

. 7 136 2

. 2 2 3 1

. 6

Nea r T o n aske t

Cumul a tive LA s/W L As (tribs.and ST Ps) 91.2 – 5 2

. 9 1 8 1 6

. 1 213 8

. 6 183 4

. 3 4 4 0 5

. 3 102 7

. 6

Bottom sedime nts 77.4-5 0 .7 203 8

. 4 3 2 8 3

. 9 202 0. 2 2 1 2 7

. 8 8 3

. 1

Loa din g cap a ci t y 50.7 385 4. 5 5 4 2 2

. 5 385 4

. 5 653 3

. 1 111 0

. 6

Near Malott

Cumul a tive LA s/W L As (tribs.and ST Ps) 91.2 – 19.5 182 6

. 0 2 1 4 7

. 2 184 1. 7 4 4 2 0

. 5 103 6

. 7

Bottom sedime nts 50.7-1 7 .0 211 3

. 7 3 3 9 5

. 1 209 7. 9 2 2 5 6

. 9 9 8

. 5

Loa din g cap a ci t y 17.0 393 9. 7 5 5 4 2

. 3 393 9

. 7 667 7

. 4 113 5

. 2

Mouth

Cumul a tive LA s/W L As (tribs.and ST Ps) 91.2 – 1 5

. 1 1 8 2 6

. 6 214 7

. 2 184 1

. 7 4 4 2 1

. 2 103 7

. 2

Bottom sedime nts 211 3

. 1 3 3 9 5

. 1 209 7

. 9 2 2 5 6

. 2 9 8

. 0

Loa din g cap a ci t y 393 9.7 554 2

. 3 3 9 3 9

. 7 667 7

. 4 113 5

. 2



# Load Reductions

Load reductions required to m eet DDT/PCB LAs are shown in Table 19. On a reach-by-reach basis, no load reductions are required to m eet LAs through delivery from t r ibutaries and STPs since subs tantial res e rve capacity exists at all reaches. As m e ntioned previously, however, som e load redu ctions are need ed to m eet loading cap a c ities in cer tain tributary stream s and STPs.

Major load r e duction s f r om bottom sedim e nts will be require d to m eet LAs f o r all re aches exc e pt where reserve capacities exist for 4,4’-DDD and 4,4’-DDT at Malott and the m outh, and 4,4’- DDT near Tonasket. No load reductions are re quired to m eet t-PCB LAs in Osoyoos Lake since PCBs have not been detected in fish from this location.

Page 38 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

### Table 19 : R e quired D D T and PCB Lo ad Red u ctio ns and R ese rv e Capacity (-) a t Osoy oos Lake a nd Lo w e r O kan ogan Riv e r Rea c hes (mg/da y )

Rea c h RM 4,4'-DDE 4,4’-DDD 4,4’-DDT t-DDT t-PCB
Os oy oos La ke
T r ibs. (reduction) 91.2-8 0 .3 -790. 7

- 1 1 3 3

. 8

- 7 9 3

. 4 -133 8

. 7

- 2 3 0

. 2
% reducti o n 0 % 0 % 0 % 0 % 0 % Sedim ents (red u ction) 82.5-7 9 .2 1 7 1 1 4

. 1 1 0 2 3 8

. 0 7 7 7

. 7 2 8 1 1 7

. 7 0

. 0
% reducti o n 1 0 0 % 1 0 0 % 1 0 0 % 100 % 0 %

Oro v ille
T r ibs. (reduction) 91.2-7 7 .8 -783. 2

- 1 1 3 3

. 8

- 7 8 9

. 9 -132 6

. 3

- 2 3 1

. 6
% reducti o n 0 % 0 % 0 % 0 % 0 % Sedim ents (red u ction) 79.0-7 7

. 4 7 9 3 3

. 9 6 6 4

. 0 2 6 5

. 8 8 8 5 8

. 8 8 2 9

. 5
% reducti o n 1 0 0 % 1 0 0 % 1 0 0 % 100 % 1 0 0 %

Rea c h RM 4,4'-DDE 4,4’-DDD 4,4’-DDT t-DDT t-PCB
Nea r T o n aske t
T r ibs. and ST Ps (reductio n ) 91.2 – 5 2 .9

- 177 9

. 5

- 2 1 3 4

. 9

- 1 8 1 9. 6

- 4 3 5 0

. 3 -102 7

. 5
% reducti o n 0 % 0 % 0 % 0 % 0 % Sedim ents (red u ction) 77.4-5 0 .7 390 0 0

. 5 1 5 8 7

. 9 -572. 2 4 5 2 3 0

. 8 640 8

. 0
% reducti o n 9 5 % 3 3 % 0 % 9 6 % 9 9 %

Malott
T r ibs. and ST Ps (reductio n ) 91.2 – 1 9 .5

- 172 5

. 1

- 2 1 3 2

. 1

- 1 7 5 0. 2

- 4 2 1 3

. 1 -103 4

. 0
% reducti o n 0 % 0 % 0 % 0 % 0 % Sedim ents (red u ction) 50.7-1 7 .0 103 6 7

. 9

- 1 9 1 5

. 2

- 1 7 9 0

. 8 1 1 9 8 6

. 8 246 7

. 0
% reducti on 83% 0% 0% 84% 96%

Mouth
T r ibs. and ST Ps (reductio n ) 91.2 – 1 5 .1

- 172 5

. 1

- 2 1 3 2

. 1

- 1 7 5 0. 2

- 4 2 1 3

. 1 -103 4

. 5
% reducti o n 0 % 0 % 0 % 0 % 0 % Sedim ents (red u ction) 17.0-0.0 103 6 7

. 9

- 1 9 1 5

. 2

- 1 7 9 0

. 8 1 1 9 8 6

. 8 246 7

. 5 % reducti on 83% 0% 0% 84% 96%

a Results shown are fo r PCB Aro c lors 1268, 1262 , 1260 , 1254 , 12 48, 1242 , 1232

, 1221, and 1016



## Reductions in DDT and PCB Conce n tra tions in Bottom Sedim e nts Accum u lation of a contam inant through all com ponents of the aquatic environm ent is often referred to as bioaccum u lation, with the num er ical relationship describ e d by bioaccu mulation factors (BAFs). For fish, BAFs are probably m o re appropriate than BCFs to describe the
contam inant link with th e aquatic en vironm en t because BCFs substan tially underestim ate the bioaccum u lation potential for hydrop hobic chem i cals that are resistan t to m e tabolism and degradation such as DDT and PCBs (EPA, 2000).

Biota-s e diment accum u lation facto r s (BSAFs) are th e s i m p lest m odel to explain the relationship between contam ination of an organism and bottom sedim e nts. BSAFs are essentially the ratio of
contam inant concentrations in tissue to concen trati ons in sedim e nt and may be used in situations where the concentration ratios do not change substantia lly over tim e, both the organism and food are exposed to the contam inant, and sedim e nt con centrations are representa tive of those in the

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 39

## vicinity of the organism . For hydrophobic chem ical s such as DDT and PCBs, this relationship is more accurately defined by factor ing in tissue lipid and sedim e nt organ i c carbon which strongly influence th e uptake and reten tion of these ch em i cals. Site-sp e cific BSAFs m a y then be calcu lated u s ing the formula:

BSAF = (C t 

## /f

l 

## )/(C s 

## /f oc 

## )

where:

C t



## = contaminant con cen tra tion in tis sue C s 

## = contaminant con cen tration in sedim e nt f l 

## = lipid f r a c tion in tissu e f oc 

## = fraction of organic carbon in sedim e nt

Current data on DDT and PCB in sedim e nts and fish tissue w e re used to establish site-specific BSAFs at Osoyoos Lake and several lower Okanogan River reaches (Table 25). Data used were

m ean DDT, PCB, and TOC concentrations in the surficial layers (top 2-cm ) of sediment cores collected from Osoyoos Lake (Osoyoos Lake and Oroville BSAFs) and from the Oka nogan River m outh (Riv-Om a k and Monse BSAFs). Fish tissue data were the sam e as those used to calcu late theoretical load s.

BSAFs gene rally ranged by approxi m a tely an order of m a gnitude (2.3 – 34.9) dem ons trating a fairly good correlation between DDT/PCB concentrati ons in sedim e nt and tissue. The BSAF for PCB at Oroville was very high due to low lipid c ontent of f

i s h com b ined with low PCB level in sedim e nts. High BSAFs for 4,4’-DDT at Riversid e-Om ak and Monse were driven by very low concentrations in sedim e nt.

Reductions in sedim e nt DDT/PCB concentrations required to m eet LAs at several Osoyoos Lake and lower Okanogan River reaches w e re calculated by applying BSAFs to required reductions in tissue concentrations (Table 26). Except for P CBs in Osoyoos Lake, complete (100%) or near

com p lete reductions are needed to m eet LA s in the Osoyoos Lake and Oroville reaches, reflecting the LAs given to sedim e nts in thes e reaches (0 m g /day). Large percent reductions are also needed for 4,4’-DDE, t-DDT, and PCBs in sedim e nts in the lowe r re aches, but re serve capacities exist in m o st cases for 4,4-DDD and 4 ,4’-DDT.

Trends in sedim e nt DDT and PCB concentrations obtained from sedim e nt cores suggest in m o st cases these required reductions will not be m e t in the near future. Concentrations have rem a ined stable for th e past two decades in th e Osoyoos Lake sedim e nts and for th e past decad e in sedim e nts at the Okanogan River m o uth.

Table 20 : BSAFs a t Oso y oos Lake and Sev e ral L o w e r Ok ano g an Riv e r Reaches Loca t ion 4,4'-DDE 4,4'-DDD 4,4'-DDT t-4,4 '- DD T t- PC B a
Oso y oos Lak e 12.6 6

. 0 1 0

. 2 8

. 9 11.3 b
Oroville 34.9 2. 3 2 1

. 7 1 6

. 8 1 2 9

. 1 Riv-Omak 21.1 9.1 162.1 c 1 9

. 0 1 5

. 1
Monse 11.3 4.9 77.1 c 1 0

. 1 1 0

. 4

a Results shown are fo r PCB Aro c lors 1268, 1262 , 1260 , 1254 , 12 48, 1242 , 1232

, 1221, and 1016
b One-half p r ac ti cal quant it ation l i m it (10 ng /g) us ed as tissue conc entra tion

c One-half pr act ic al qu anti tat i on li m it (0.032 ng/g) used as sedimen t concentr ation



### Page 40 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

### Table 21 : R e duc tions or Reserv e Ca pacit y (-) in Sediment D D T and PC B Conc ent r ati ons (ng/g O C ) Requir e d to Meet Lo ad Allocations
Rea c h 4,4'-DDE 4,4’-DDD 4,4’-DDT t- DDT t-PC B a

Os oy oos La ke Current co nc. 822 1

, 0 4 3 4 6

. 5 1

, 9 1 2 1 3

. 5 Red u ction re qu ired to meet LA 822 1,030 48.0 1,905 0.0
Percent red u cti on 100 % 99% 100 % 100 % 0% Oro v ille Current co nc. 822 1

, 0 4 3 4 6

. 5 1

, 9 1 2 1 3

. 5 Red u ction re qu ired to meet LA 820 1,043 46.5 1,912 13.5
Percent red u cti o n 100 % 100 % 100 % 1 0 0 % 1 0 0 %
Nea r T o n aske t Current co nc. 354 97.4 1.6 b 4 5 3 4 5

. 6
Red u ction re qu ired to meet LA 336 37.8 -0.4 431 45.6
perce nt reducti on 95% 39% 0% 95% 100 %
Malott Current co nc. 354 97.4 1.6 b 4 5 3 4 5

. 6
Red u ction re qu ired to meet LA 308 -97.4 -6.7 398 45.6
Percent red u cti on 87% 0% 0% 88% 100 % Mouth Current co nc. 353 97.4 1.6 b 4 5 3 4 5

. 6
Red u ction re qu ired to meet LA 308 -97.4 -6.7 398 45.6
Percent red u cti on 87% 0% 0% 88% 100 %

a Results shown are fo r PCB Aro c lors 1268, 1262 , 1260 , 1254 , 12 48, 1242 , 1232

, 1221, and 1016
b One-half p r ac ti cal quant it ation l i m it (0.032 ng/g) used as sedimen t con centr ation



## Load Reductions in Individual Tributaries and S T Ps
Table 27 shows load reductions needed to bring indi vidua l tr ibutar ies and STP in line with Washington State and N T R criteria. In general, required load reductions are less than 10 mg/day. Tallant, Elgin, Tonasket, and Ninem ile Creeks will require the la rgest load r e duction s

. Three of these stream s – Tallant Creek, Elgin Cr eek, and Ninem ile Creek – are currently on the 303(d) list f o r t-DDT. The Okanogan STP was th e only one of the three STPs requiring load reductions for DDT and PCBs.

Table 22 : Load Red u ctio ns Req u ired to Mee t Cr iteria w i thin Indi v i dual Trib utaries and STPs (mg/da y )

Loca t ion RM 4,4'-DDE 4,4'-DDD 4,4'-DDT t- DDT t-PC B a

Ha yn es Creek BC 82.8 1.0 0 0 0.8 0
Nine Mi le Cr ee k 80.2 4.6 0 2.8 10.2 0
T o n a s k e t Cree k 7 7

. 8 7

. 4 0 3

. 5 1 2

. 4 0 Mosqu i to Cree k 67.4 0.6 0.5 0 1.4 0
W h itestone Cr eek 6 2

. 4 0

. 8 0 0 0 0
Antoin e Cre e k 61.2 2.8 0 0 3.1 0 Elgi n Creek 28.4 1 2

. 5 0 5

. 3 1 9

. 0 0 Okanog an ST P 24.8 0 0 0.3 0.8 0.2
T a llant Creek 19.5 4 6

. 4 1 0

. 2 6 8

. 4 1 2 5 0

a Results shown are fo r PCB Aro c lors 1268, 1262 , 1260 , 1254 , 12 48, 1242 , 1232

, 1221, and 1016



### Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 41

# Seasonal Variation

Seasonal variation has been addressed through sa mpling during low flow and high flow events. Use of weighted m ean loads also in corporates fl ows and contam inant concentration s m easured at various tim es of the year.

Both the hum a n health and chronic aquatic lif e criteria for D D T and PCBs are driven by longterm exposures. Acute toxicity is not considered to be a concern at concentrations in the lower Okanogan River basin (E PA, 1980a; EPA, 1980b). Since the accum u latio n of DDT and PCBs in fish tissues is a tim e-integrative process, and the chronic aquatic life cr iteria are based on longterm exposures, seasonal variations in loads are not an im portant factor in determ ining load alloc a tion s f o r these p a ra m e ters.



# Margi n of Safety

The federal Clean W a ter Act require s that a m a rg in of safety be identified to account for uncertainty when establishing a TMDL. The m a rgin of safety can be explic it in the f o rm of an allocation, or im plicit in the use of conser vative assum p tions in the analysis.

A large portion of the Margin of safety in this T M DL is the l ong standing bans on use of these persistent compounds in the environm ent. As th e reduction of contam inants in the system is observed, no new sources will occur. The non-point nature of DDT and PCBs and the difficulty to dir ectly c ontrol thei r discharg e to the water have abated over tim e and the im provem e nts to land and water m a nage ment within the valley a ssures im proving long term control of non-point
contam inant m i gration pathways. This TMDL also relies on the conservative m eans by which the criteria have been set for the DDT and PCB rela ted contam inants for the m a rgin of safety. Additiona lly ; this m a rgin of saf e ty is enhanced by the leg acy n a ture of the contam inants addressed in this TMDL, the con centrations of contam inants s hould continue to decline even af

ter the reg u lato ry cr ite ria hav e bee n m e t.

Page 42 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Summary Implementation Strategy

Introductio n Pursuant to the 1997 Memorandum of Agree m en t between Ecology and the EPA, a Summary Im plem entation Stra tegy (SIS) is incl uded in th is subm ittal re port f o r the Okanogan River DDT and PCB Total Maximum Daily Load Project . T h is goal of this SIS is to present a clear, conc ise and sequential concept of how suspended DDT a nd PCB pollution will be reduced within the Lower Okanogan basin in order to m eet th e fish tissue and su rface water criteria for DDT and PCBs. It is anticipated that im plem e n tati on of the TMDL will return th is water body to conditions that m eet the target s and criteria noted above by July and 2054. The SIS com p lies with the federal m a ndate of the Clean W a ter Ac t, State laws to control point and non-point source pollution, and the 1997 Mem o randum of Agreem ent between EPA and Ecology.

A citizen’s workgroup that was form ed as the Implem entation Comm ittee under the Okanogan Watershed Water Quality Managem e nt Plan s e rved as citizen repres entatives in the developm ent of this TMDL and im plem entation strategy. Groups represented in the T M DL workgroup include ir rig a ted ag ricu lture, ranchers, conservation districts and natural res ource ag en cies,

recr eational inte rests, as well as num erous other interested partie s or stakeholders, agencies and organizations. There is a high level of cooperation and communication between project participants, and their continued active pursuit of the goals TMDL’s and watershed m a nagem e nt plan, m a ny of which are shared by both the TM DL and the Okanogan Watershed Water Quality Managem e nt Plan, will u ltim ately en sure the suc cess of this TMDL.

The strategy to im ple m ent the TMD L is based u pon actions already taken to address contam inant sources, the continuation of the m a ny existing e fforts, and the im ple m entation of new actions. The non-point sources (load allo cations) will b e addressed b y the use of best m a nagem e nt practices (BMPs). Point sources (NPDES disc hargers) are already working to understand the source of contam inants in their discharges a nd will continue to work under the NPDES program to reduce their contam inant loading to the Okanoga n River. The principal focus of this TMDL im plem entation str a tegy will be to co ntinue the re moval of potentia l sour ce s of contam ination from the watershed and the im ple m e n tation of seasonal and year-round BMPs to prevent the entry of pers isten t residu es of DDT a nd PCBs into area waterbodies. Addition a lly, co ntinued monitoring of i m ple m entation activities and fish tissue con t a m inant levels and water quality are essential in assess ing th e natu ral attenuation of contam inants.

This SIS will serve as guidance for developing a Detailed Implem entatio n Plan (DIP) during the
one-yea r per i od af ter the TMDL has been approv ed. The DIP will des c rib e specif ic im plem entation activitie s that n eed to be perf or m e d to achieve the TMDL targe t s. T h e DIP will also present a thorough plan for m oni toring im plem en tation of this TMDL. It is anticipated that im ple m entation of this T M DL will docum ent long-te rm redu ctions in the DDT and PCBs in fish from the Lower Okanogan River Basin.

The technical assessm e n t report identified the sedim e nts within the Okanogan River as the prim ary load of contam i n ants. The restoration tim e fra m e for this TMDL is prim arily dependent on the natural breakdown of these pe rsistent chem icals in the environm ent. Lim ited early data

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 43

## on fish tissue concentrations suggest a downward (im p roving water quality) trend in fish tissue concentrations when compared to data reporte d from the latest TMDL study. Data collection and analysis for fish tissue prior to the TMDL Technica l Ass e ssm ent report is insuf f i cient f o r the establishm ent of baseline data. The downward trend cannot be determ ined due to the lim ited

am ount of the early data. The current TMDL a ssessm ent report does provide sufficient data for reference by future fish tissue studies

Implementation Activ i ties This TMDL is addressing water quality im pairme nt from legacy loading. The prim ary actions for reducing DDT and PCB in the environm ent was the regulatory ban on DDT use in 1972 and the 1979 ban on PCB pr oduction, and the subsequent phase-out and control of PCB pr oducts.

A downwar d trend in DDT and PCB concentrations following the above bans is evident in the sedim e nt cores from the south basin of Lake Osoyoos and the lowest segm ent of the Okanogan River. This downward trend, however, is not continuous in the Lake Osoyoos coring and exhibits an anom alous spike of high concentra tion in the past d ecade. This trend i ng data suggests two courses of actions are needed to address continuing inputs of DDT to the watershed; continued implem entation of BMPs to reduce pes tic ide re sidu es reaching the affected surface waters and efforts to rem ove DDT containing products for the watershed.

Implementation Activ i ties for Non-Point Sources Several tributary streams w ithin the Okanogan Basin were identified as carrying DD T
contam ination. Specific source areas of non-point contam ination were not apparent and not identified by the technical assessm e nt.

Lands that were in ag ricultu ral production during the tim e period that DDT was in common
usage are co nsidered po tential s ources of DDT due to the residue s of DDT that pe rsis t in th e soils. Erosion of these lands can be the source of contam inated river system s as shown in the report: A Suspended Sediment and DDT Total Maximu m Daily Load Evaluation Report for the Yakima River . In that report DDT loading to the Yaki m a River was found to correlate strongly with the am ount of sedim e nt derived from agricu ltural runof f. Irrigation practices in the lower Okanogan River basin do not produce the am ounts of sedim e nt loading to the river that were seen in the Yakim a exa m ple, even though pestic ide application practices were sim ilar in both basins at the tim e, which suggests that agricultur al soil losses in the Ok anogan are not as great a source of DDT as in the Yakim a River area surface waters.

Historical improvem e nt s in irri gation delivery system s in the lower Okanogan River basin have resulted in the current irrigation sys t em s efficien tly prov idin g water to th e lands. Ac cording to the Okanogan Conservation District, irrigation practices that result in significant soil loss, such as open rill irrigation, are no longer practiced in the lower O k a nogan Basin. Investigations in the lower Okanogan River basin by Ecology and the Colv ille Confederated Tribes did not docum ent the discharge of irrigation dr ains in the Okanogan valley.

Experience in other irrigated ri ver basins, like the lower Yakim a River Basin, has shown that a

move m e nt to enclosed irrigation system s, like spri nklers or drip system s, effectively reduces the

am ount of pesticide residues carried from agri cultural lands into nearby surface waters.

Page 44 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

## Continuing improvem e nt s to irrigation efficiency and water delivery system s may continue to decrease the soil th at m i grates d i rectly from the agricu ltu ral lands. Th erefore, working with irrigation water m a nagem e nt to produce efficien t irrigation practices will also redu ce the transport of DDT residues fr om the agricu ltu ral lands.

BMPs that work directly with the riparian lands located betw een the cu rrent and former agricu ltu ral lands to red u ce losse s of soils that po tentially con t ain pesticid e residu es a r e actively
prom oted through program s including: EQUIP, CREP, CRP, and Ecology adm i nistered grants of Centennial Clean W a ter funds, 319 funds and Sa lmon Recovery Funds. These funding sources are not d e dicated on ly for projects that redu ce DDT in surface waters, bu t are directed toward reducing a variety of pollutants. Many of the project s, such as exclus ion fencing to restrict cattle from riparian areas that are prom oted for envi ronm ental restoration and preservation can have the side benefit of DDT reduction through the prevention of erosion.

Potential sources of DDT contam ination, other than agricultural soil erosion, have been suggested for the tributary stream s. An exa m ple of this is a com p laint that has been filed with the Ecology that an old orchard dum p in the vici nity of Highway 20 crossing Talent Creek m a y be a continuing source of DDT contam ination. Such com p laints regarding inappropriate disposal will be inves tiga t ed thou gh the W a shington Sta t e Model Toxics Control A c t and oth e r State regulations as appropriate.

Re m oving potential sources of DDT in the wate rshed is an important step in reducing the
contam ination in the Okanogan watershed. Prog ram s for the collection of banned pesticides, including DDT, have been successfully im plem e n ted in both Washington and British Colum b ia,

rem oving many stored pesticides from the wate rshed. The waste pesticide pickup program s , such as the one conducted by the Washington D e part m e nt of Agriculture, reduces the potential of inappropriate disposal or accidental loss of DDT, or any other wast e p e stic ide, in th e watershed. Losses of DDT-contai ning m a terials could result fr om catastrophic losses from storage facilities through flood, fi re, or inappropriate disposal ac tivities. Such a disposal or catastrophic loss of stored m a te rials could account for the spike in concentrations found in the sedim e nt core from sout hern Lake O s oyoos.

Addressing PCB conta m ination in the lower Oka nogan River Basin is m o re problem atic than addressing the DDT pesticide. The prim ary uses of PCB were not intended f o r disper sal in to the environm ent, but its environm ental persistence is sim ilar to th at of DDT. Efforts to re duce PCB releases to the environm ent will include edu cation efforts for disposal of potential PC Bcontaining m a terials common to industry, sm all businesses and households. Proper disposal of item s and mater i als tha t potential ly contain PCBs m a y be achieve d through the existing m oderate risk waste facility operated by Okanogan County. An experim e ntal effor t to collect and test sedim e nt from storm drains in m unicipal areas has been proposed for the municipalities of Tonasket and Okanogan. This effort has the potential to co llect PCBs from the urban environm ent and analy tically test collected m a te rials to d e term ine the success of the p r oject and its potential future applications in the valley.

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 45

## Implementation Activ i ties for Point Sources (NPDES) The NPDES perm itted dischargers in the Lower Okanogan Basin are the municipal w a stewater treatm ent plants in Oroville, Tonasket, Om ak and Okanogan. These facilities are the only potential point sources in the TMDL study area.

The NPDES discharge perm its for the cities of Oroville Om a k and Okanogan have recently been renewed. Coordination between the NPDES pe r m it developm ent and the ongoing developm ent of this TMDL has resulted in each of these pe rm its containing requirem e nts to inves tig ate th e wastewater collection sy stem s for the sources of DDT and PCBs in their effluent. An effort is being m a de to undertake a coordinated investigat ion of wastewater collection system s of these municipalities and the w a stewater co llec tion and trea tm ent system f

o r the city of Tonasket. The purpose of investigating the wastew at er collection system s is to determ ine if there is a discreet o r concentrated source of contam inants entering th e system s that m a y be addressed efficiently before the contam inants enter the w a stewater treatm ent plants.

The city of Tonasket was not included in the sampling for the technical assessm ent study as it was not discharging to the rive r at the tim e of the study. The city of Tonasket has since

com p leted construction on an upgraded wastewater treatm ent system and is now discharging to the river. T h e NPDES perm it was not conditioned with a requirem e nt for investigating potential sources of DDT. However, the city of Tonasket has expressed a willingne ss to participate in DDT studies in anticipation of their next perm it cycle.

Monitoring Strategy The persistent natures of DDT and PCBs in the environm ent truly m a ke them a legacy of past practices. While these toxic com pounds continue to persist in the envi ronm ent their effective levels are reduced over tim e through degradati on and by natural attenua tion through dilution and capping. The natural processes resulting in the lower exposure of aquatic life to the
contam inants will play a m a jor role in the succ es s of this TM DL. Monitoring f i sh tiss ue concentratio ns of these contam in ants will be the most effective m eans to judge the p r ogress of environm ental im provement.

Analytical testing results fo r fish tissue sam p ling for the 2003 TMDL Technical Assessm ent report show DDT and PCB values that appear to be substantially lower than the fish tissue

sam p les that were taken in the period of 1984 – 1995. Unfortunate ly, there is insufficient data from 1985-1995 to determ ine if this apparent reduc tion of contam ination in fish tissue is truly significant. The fish tissue data from the 2003 Technical Assessm ent repor t will serve as the baseline data to judge progress of environm en tal im prove m e nt. Repeating the fish tissue

sam p ling efforts on a reg u lar cy cle of 5 years is recommended for the tracking of effec tive water quality im provem e nts.

Responsible Entities an d Actions The Okanogan Conservation District adm i nisters most of the incentive based or grant funded
program s for the restoration and pr eservation of riparian lands, and the reductions of soil losses on agricultural lands. It is im por tant that the Okanogan Conservati on District continue to serve

Page 46 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

## this role of coordinati ng grant funded projects in the waters hed as they have the local knowledge and community con t acts that are es s e n tia l to the success of th ese progr ams.

The m unicipalities of Oroville, Tonasket, Om ak and Okanogan are responsible for the

com p liance of their m u nicipal wastewater trea tment plan ts with the i r NPDES perm its. The linkage between the NPDES and TMDL program s through the US Clean W a ter Act assures that the goals of the TMDL will be re f l e c ted in their NPDES perm its.

Ecology will be responsible for the periodic m onitoring of DDT and PCBs in fish tissues. Maintaining this responsibility within the state agency should provide consistent data quality.

Ecology is the responsible entity for determ ining com p liance of interim and final targets, and conducting Effectiveness Mon itoring in the future.

Adaptive Management
These im plem entation activities are centered on the m a intenance and im provem e nt of long term activ ities th a t have r e duc ed water con t am inant levels since the banning of DDT and PCBs. The inclus ion lo ng-term data colle ction a nd m onitoring of f

i sh tissue in th e implem e ntation activ ities is neces sary due to the p e rsis ten t nature of th ese legacy con t am inants. The m onitoring activ ities will serve to better defin e the rate th at the water quality in th e basin is im proving. Re-evalu ation of the long-term trends with addi tional data will allow the restora tion timefram e to be determ ined with greater precession. If the water quality m oni toring activitie s show un expected lon g -term rises of contam inants in fish tissues, an exam ination of any potential new sources of DDT or sedim e nts should also b e undertaken. Add ition a lly, intens ive surveys and watershed investigation should be sought to identify significant events in the watershed that could resuspend sedim e nts.

Persistent elevated values of DDT or PCB conta m ination, or data that does not show the expected g r adual declines over tim e , will tr igger additional in vestig ation under adap tive

m a nage m e nt . This should include, but not be limite d to, further the invest igations of tributary
stream s and potential gro undwater transport of DDT.

Potential Funding Sources Funding sources will be more fully expl ored in the developm ent of the DIP.

At this tim e funding for the periodic (repeati ng every five years) m onitoring of the lower Okanogan basin fish tissue is expected be accom p lished with project funding through the norm a l operations of Ecology. Opportunities for exte rnal funding sources and adjustm e nt to the frequency of study even ts will be con s idered as th e body of data and tim e related trends are

accum u lated.

Funding for the W a shington Departm e nt of Agri culture’s waste pesticide pickup program is currently sustained through the Depa rtm e nt of Agriculture. The be nefits of such a program to water quality are direct but difficu lt to quantif y as it is a pr ev entive p r ogr am . At this tim e the
program appears to b e well suppo rted and will c ontinue to b e available in the Okanogan Valley.

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 47

## The communities of Tonasket and O k anogan ar e seeking grant funding for the experimental effort to collect and test sedim e nt from storm drains in m unicipal areas. T h is independent work by the cities m a y be faci litated through the e fforts of the Okanogan Conservation District.

Detailed I m plementa tio n Plan A DIP will be prepa r ed within a ye a r f o llowi ng approval by EPA of this docum ent. Further public input will be soug ht to he lp prepare the plan. The plan will id entify in m o re detail how, when, and where m onitoring activ ities will be implem ented. Ecology and other en tities will provide technical assistance and seek additional f unding for these m onitoring activities and any restoration activities that m a y be identified as the body of data grow s. It is the goal of this TMDL to meet the water quali ty standards for DDT in surface waters and 4,4’-DDD, 4,4’-DDE and PCBs in fish tissues by 2054.

Page 48 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Activities that Support this TMDL Implementation Strategy

The im ple m entation strategy for the Okanogan DDT and PCB TMDL is designed to address legacy loading of DDT and PCBs in the waters hed from historic agri cultural, industrial, commercial and dom estic prac tice s in the wa tershed. Im plem entati on activ ities inc l ude continued implem e ntation of activit ies that have reduced or contro lled releases of con t am inants to the su rf ac e waters and the continu e d inves tig ation of potential contam inant sources in the Okanogan River Tributaries. 

# Supporting Regul a tions and Land Management Plans

Routine im plem entation of W a shington’s State E nvironm ental Policy Act, the Okanogan County Com p rehensive Plan and the Okanogan County Shor eline Master Prog ram will assure the review of projects proposed in the vicinity of the Okanogan River and tributaries for potential environm ental im pacts due to erosion. This re view process should ensure best m a nagem e nt practices are used f o r new projects a nd th at pe rmitted activities will no t impact the im ple m entation of this T M DL. Continued im plem entation of W a shington’s Model Toxics Control Act should provide continued support for the investigation of potential contam inated sites that are uncovered over tim e , s u ch as dum p sites tha t in clude DDT and PCB containing

ma t e r i a l s

. 

# Reasonable Assurance

During the developm ent of the DDT and PCB TMDL for the lower Okanogan River basin, available data for water quality throughout the w a tershed was collected and evaluated. The m a ss balance approach to the TMDL and the quantity of data has shown that th e loading of these legacy contam inants are far reduced f r om the tim e that they were in active use. W ithout new sources of contam inant entering the watershed, the downward trend should continue though at a much declined rate from what has been seen in recent years as indicated by the sedim e nt core

sam p les and dating conducted as part of the TMDL technical assessm ent. The rate of natural attenuation due to degradation, d ilution and sequestering of m a terials in the deep sedim e nts can only be es tim a ted with the curr ent se t in da ta. Docum e ntation of the a ttenuation will take longterm m onitoring of fish tissue in the river system . The conservative assumptions used in setting the regu lato r y criter ia, an d the work b y the NP DES perm itted f acilities sho u ld provid e suf f i cient assurance that, with tim e, water quality is im proving.

Each of thes e conserv a tive m easures will assu re that the Okan ogan W a ters hed will be monitored and protected from activities that would thr eaten the wate r qu ality while the legacy lo ading is

m itigated th rough tim e and nature.

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 49

# Public Participation

Public involvem ent is a required part of the TM DL process. The public participa tion activ ities perform e d to date for this TMDL are included in appendix A “Summ a r y of Public Involvem e nt”. Additional public involvem e nt activities will be included in preparation of the Detailed Im ple m entation Plan.

Page 50 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Refer e nces

Davis, D. and A. Johnson, 1994. W a shington State Pesticide Monitoring Program – Reconnaissance Sam p ling of Fish Tissue and Sedim e nts (1992) . W a shington State Departm e nt of Ecology, Olym pi a, WA. Ecology Pub. No. 94-194.

Davis, D. and D. Serdar, 1996. W a shington State Pesticide M onitoring Program - 1994 Fish Tissue and S e dim e nt Sampling Report . W a shington State Departm e nt of Ecology, Olym pia, WA. Ecology Pub. No. 96-352.

Davis, D., D. Serdar, and A. Johnson, 1998. W a shington State Pesticide Monitoring Program - 1995 Fish Tissue Sam p ling Report . Washington State Depart m e nt of Ecology, Olym pia, WA. Ecology Pub. No. 98-312.

Ecology, 1993 (Revised 1997 and 2002). Assessm e nt of Wat e r Quality for the Section 303(d) List . W Q P Policy 1

- 11, Washington State De partm e nt of Ecology W a ter Quality Program , Ol ym pia, W A

. Ecology, 1995. Department of Ecology Investigati on of PCBs in the Spokane River . Washington State Departm e nt of Ecology, Ol ym pia, WA. Ecology Pub. No. 95-310.

Ehinger, W

. , 1994. Am bient Monitoring Scoping Report for the Okanogan Planning Basin (WRIAs 48-51) . W a shington State Departm e nt of Ec ology Environm ental Investigations and Laboratory Services Program , Olym pia, WA.

EPA, 1980a. Am bient W a ter Qua lity Crite ria f o r DDT . U.S. Environm enta l Pro t ec tio n Agency, Office of Water, Regulations and Standards, Criteria and Standard s Division, W a shington DC. EPA 440/5-80-038.

EPA, 1980b. Am bient Water Quality Criteria for Polychlorinated Biphenyls . U.S. Environm ental Protection A g ency, Office of W a ter, Regulatio ns and Standards, Cr iteria and Standards Division, Washington D C . EPA 440/ 5-80-068.

Harris, M. J., L.K. W ilson, J.E. Ellio tt, C. A. Bishop, A.D. Tom lin, and K.V. Henning, 2000. Transfer of DDT and M e tabolites from Fru it Orchard Soils to Am erican Robins ( Turdus migratorius ) Twenty Years after Agricult ural Use of DDT in Canada. Archives of Environm ental Contam ination and T oxicology 39: 205-220.

Hopkins, B., D. Clark, and M. Stinson, 1985. Basic W a ter Monitoring Program Fish Tissue and Sedim e nt Sampling for 1984 . Ecology Pub. No. 85-7, W a shington State Departm e nt of Ecology, Olym pia, W A

. Hurst, D., Fulcrum Environm ental Consulti ng, Inc., written comm unication, October 15, 2001.

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 51

## Hurst, D. and P. Stone, 2002. Signature or Static? Di stribution of Arsenic, Lead, and t-DDT in Sedim e nts of the Okanogan River from Lake Os oyoos to the Colum b ia River

. Presentation at Colum b ia River Trans boundary Conference, April 27 – May 1, 2002, Spokane, WA.

Johnson, A., D. Norton, and B. Yake, 1988. Persiste nce of DDT in the Yakim a River Drainage, Washington. Arch. Environ. Contam . Toxicol. 17:289-297.

Johnson, A. and D. Norton, 1990. 1989 Lakes and Reservoir Water Quality Assessm ent Program : Survey of Chem ical Contam inants in Ten W a shington Lakes . Washington S t ate Departm e nt of Ecology, Olym pia, WA.

Johnson, A., D. Serdar, and D. Davis, 1997. DDT Sources to the Ok anogan River and Lake Osoyoos . Mem o randum to Jim Milton, W a shington State Departm e nt of Ecology, Olym pia, WA.

Johnson, A. and R. Polotnikoff, 2000. Review of Sedim e nt Quality Data for the Sim i lkam een River . W a shington State Depart m e nt of Ecology, Olym pia, WA. Ecology Pub. No. 00- 03-027.

Johnson, A., W a shington State Departm e nt of Ec ology, personal comm unication, 2001.

Joy, J. and B. Patterson, 1997. A Suspended Sedim e nt and DD T Total M a xim u m Daily Load Evaluation Report for the Yakim a River . W a shington State De partm e nt of Ecology, Olym pia, WA. Ecology Pub. No. 00-03-027.

Neslen, T., Okanogan County Conservati on District, personal communication, 2001.

Reif, D., 1990. Okanogan W a stewater Treatm ent Plant Class II Inspection: October 18-19, 1988

. Washington State Departm e nt of Ecology, Olym pia, WA.

Serdar, D., D. Davis, and A. Johnson, 1998. DDT in Osoyoos Lake Fish . Washington State Departm e nt of Ecology, Olym pi a, WA. Ecology Pub. No. 98-337.

Serdar, D., 2002. TMDL Technical Assessm ent of DDT and PCBs in the Okanogan River Quality Ass u rance Pro j e c t Plan . W a shington State Departm e nt of Ecology, Olym pia, WA.

Sinclair, P. H. and J.E. Ellio tt, 1993

. A Survey of Birds and Pestic ide Us e in Orcha r d s in the South Okanogan/Sim ilkam een Regi on of British Colum b ia, 1991 . Canadian W ildlife Service, Pacific and Yukon Region. Tech. Rep. Series No. 185.

WEST Consultan t s, Inc. and Ha mm ond, Collie r, & W a de-Livingstone, In c., 1999 (Draft). Wa t e r Quality Mo deling Asses s m e nt of the Okanogan River . Prepared for Okanogan County Water Resources Departm e nt, Okanogan, W A

.

Page 52 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Defini tions and Acronyms

303(d) Section 303(d) of th e federal Clean Water Act
B.C. British Co lu mbia

BAF bioaccum u lation facto r BCF bioconcentration factor
BSAF biota-sedim e nt accum u lation facto r
BW body weight
C s 

## concentration in sedim e nt
C t 

## concentratio n in tis sue C w 

## concentratio n in water
CCT Colville Confederated T r ibes
CFR Code of Federal Regu lations, usually preceded by chapter nu mber and followed by a section num b er (i.e. 40CFR131.36)
cfs cubic feet per second
CW A Clean W a ter Act

DDD 1,1-dichloro-2,2-bis( p -c hl orophe nyl )et h ane (a .k.a . 4,4’- DDD)

DDE 1,1-dic hloro- 2,2-bis ( p -c hl orophe nyl )et hyle n e (a.k.a . 4,4’- D DE) DDT 1,1,1-tric h lor o -2,2- bis( p -c hlor ophenyl) etha ne ( a .k.a . 4,4’

- D DT a nd als o use d to re fer to the DDD and DDE analogs)

DIP Detailed Implem entatio n Plan Ecology Washington State Departm e nt of Ecology
ECD electron capture detector

EPA U.S. Environm ental Protection Agency
FC fish consumption g/day gram s per day
GC gas chrom a tography
HHC hum a n health criteria

LA load allocation

MEL Manchester Environm ental Laboratory mg/l m illigram s per lite r (pa r ts per billion)
MOS m a rgin of sa fety
m.s.l. m ean sea level

NDIR nondispersive infrared

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page 53

## ng/g nanogram s per gram (parts per billio n) ng/l nanogram s per liter (parts per trillion)
NIST National Ins titu te of Standards and Technology
NPDES National Po llutan t Disch a rge Elim ination Syste m
NTR National Toxics Rule (40CFR131.36) Q discharge q1* cancer slope factor
Pb lead
PCB polychlorinated biphenyl

Ra radium
RCW Revised Code of W a shington

RF risk facto r
RM river m ile

Rn radon
SIS Su mm ary Implem entation Plan
SRM standard ref e rence m a te ria l
STP sewage treatm e nt plant

t-DDT total DDT (su m of 4,4’-DDD, 4,4’-DDE, and 4, 4’-DDT in this report)

TMDL Total Max imum Daily Load
TOC total organic carbon
TSS tota l suspen ded solids μg/l m i crogram per lite r (pa r ts per b i llion )
USDA U.S. Departm e nt of Agr i culture
USGS U.S. Geological Survey
WAC Washington Adm i nistrative Code
WC water consumption

WDFW Washington Departm e nt of Fish and W ildlife

W L A waste load a lloca tion

WWTP Wastewater Treatm e nt Plant μg/L m i crogram s per liter

Page 54 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

# Appendix A

Summar y of Public Involvement

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page A- 1

# Summary of Public Involvement

Septem ber 12, 2000 Met with the Okanogan Health District Board to present introductory inform ation on the Okanogan DDT/PCB and Sim ilkam een arsenic T M DLs.
Nove m b er 7, 2000 Presentation on the Okanogan and Sim ilka m een TMDLs m a de to the environ m ental scien ce cl ass at Wenatchee Community College class at the Om a k branch campus. Septem ber 7, 2000 Presentation to the Okan ogan Conservation District Supervisor’s

m eeting to introduce the Sim ilka m een arsenic and Okanogan DDT/PC B T M DLs. February 22, 2001 Public m eeting at Okanogan PUD to kick -off Okanogan DDT/PCB and Sim ilkam een Arsenic TMDLs. July 26, 2001 Presentation on the Okanogan DDT/PCB and Si m ilka m een arsenic TMDLs to the Okanogan Watershed Implem entation

comm ittee. August 9, 2001 Presentation to the Orovi lle-Tonasket irrigation District on the Okanogan DDT/PCB and Sim ilka m e e n arsenic T M DLs. October 25, 2002 Meeting with the Okanogan W a tershed Im ple m e n tation Comm ittee to discuss the Sim ilk a m een River arsenic TMDL and the Okanogan River DDT/PCB TM DL. February 24, 2003 Meeting with th e Okanogan W a tershed Im ple m e n tation Comm ittee to discuss the Sim ilk a m een River arsenic TMDL and the Okanogan River DDT/PCB TM DL.
June 24 2003 Meeting with Tonasket C ity Council to discuss the Okanogan DDT TMDL and the im plica tions f o r the newly perm itted municipal w a ste water discharge. July 24, 2003 Meeting with the Okanogan W a tershed Im ple m e n tation Comm ittee to discuss the Sim ilk a m een River arsenic TMDL and the Okanogan River DDT/PCB TM DL. Septem ber 2003 Okanogan DDT/PCB Te chnical Assessm ent Report was posted to the W a shington Departm e nt of Ec ology W e b Page. Notif ication s of report a v ailab i lity w e re sen t to implem e ntation

comm ittee inviting them to cont act E c ology for a report copy(s) suited to the i r needs, do wnloaded f r om the inte r n et/e -m ail,

m a iled digital copy on disk or printed hard copy. June 8, 2004 Notification of public co mment period and public m eetings placed on th e W a shingto n Departm e nt of Ecology’s internet public involvem e nt calendar.

Page A- 2 Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load

## June 11 through July 12, 2004 Public Comm ent Period for the Lower Okanogan Rive DDT/PCB TMDL Subm itta l repo rt. Advertisem ents f o r the public com m e nt period and public m e etings were placed in the larges local newspapers Oka nogan Chom ical and the Okanogan Valley Gazette Tribune June 7 to 11 and again on the week of June 14 to 18. June 16, 2004 Public m eeting held in the evening at the Okanogan Public Utility District #1 Office in Okanogan. Meeting p r ovided a f

o rum to discuss the TM DL Subm ittal Report. June 29, 2004 Public m eeting held in th e evening at the Oroville City Hall. Meeting pro v ided a f o ru m to discuss the TMDL Subm ittal Report.


# Responses to Public Comments on the Lower Okanogan River Basin DDT and PCB Submittal Report Draft
No public comm ents were received on the Lower Okanogan River Basin DDT and PCB Subm ittal R e port Draf t. Changes to the docum ent were m a de as a resu lt o f comm ents received fro m the United States Env i ronm enta l Protection A g ency in regards to required contents and clar if ication

. Adjustm e nts to th e loa d alloc a tion were m a de due to the inclus ion of a W a ste Loa d Allocation f o r the rec e n tly pe rm itted discha rge f o r the Tonasket Waste W a ter Treatm e nt Plant.

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page A- 3

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# Appendix B

Technical Report

TMDL Technical As sessment of DDT and PCBs in the Lo wer Okanogan River Basin July 2003

Ecology Publication Num b er 03-03-013

This publication may be viewed at the follow i ng w e bsite: http://www.ecy.wa.gov/pubs/0303013.pdf



# Paper copy may be obt ained upon request



# .

Lower Okanogan River Basin DDT and PCBs Total Maximum Da ily Load Page B-1

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