# Mission Creek Watershed DDT Total Maximum Daily Load

Water Quality Improvement Report

July 2007
Publication Number 07-10-046

# Mission Creek Watershed DDT Total Maximum Daily Load

Water Quality Improvement Report

Prepared by:

Ryan Anderson Washington State Department of Ecology Water Quality Program

July 2007
Publication Number 07-10-046

### You can print or download this do cument from our Web site at: http://www.ecy.wa.gov/biblio/0710046.html

For more information contact:

Department of Ecology Water Quality Program Central Regional Office 15 W Yakima Ave, Suite 200

Yakima, WA. 98902-3401

Telephone: 509-454-7844

Adams

Asotin Benton Chelan Clallam

Clark Columbia

Cowlitz Douglas Ferry

Franklin Garfield Grant Grays

Harbor Island

Jefferson

King K

i t s a p

Kittitas

Klickitat Lewis ic Lincoln

Mason Okanogan

Pacif Pend

Oreille

Pierce San Juan

Skamania Spokane Stevens

Thurston Skagit

Snohomish

Wahki Walla

Walla Whatcom

Whitman

Yakima akum 

### Northwest
425-649-7000

Southwest
360-407-6300 Eastern
509-329-3400 Central
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Regional

Office

location

Spokane

Yakima Lacey Bellevue



### Persons with a hearing loss can call 711 for Washington Relay Service. Persons with a speech disability can call 877-833-6341.

If you need this publication in an alternate fo rmat, please call the Wa ter Quality Program at 509-454-7844. Persons with hearing loss can call 711 for Washington Relay Service. Persons with a speech disability can call 877-833-6341

# Table of Contents

List of Figures

............................................................................................................................... .. ii

List of Tables

............................................................................................................................... ... ii

Executive Summary .......................................................................................................................iii

Acknowledgements ......................................................................................................................... v

Introduction

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

TMDL Process Overview ............................................................................................................... 3 Elements required in a TMDL ..................................................................................................................3 Background...............................................................................................................................................4 Applicable water quality criteria ..............................................................................................................6
Human health criteria

............................................................................................................................... 6 Water quality and resource impairments ..................................................................................................7
Seasonal variation .....................................................................................................................................7
Stormwater ...............................................................................................................................................8



### Technical Analysis .......................................................................................................................... 9 Study design .............................................................................................................................................9 Sample locations .......................................................................................................................................9 Data analysis

............................................................................................................................... ............11
Results

............................................................................................................................... .....................12 DDT concentrations in surface water and shallow ground water ...........................................................12



### Loading Capacity and Load Allocations ....................................................................................... 17 Total DDT targets

............................................................................................................................... ....17 Margin of safety

............................................................................................................................... ......18



### Summary Implementation Strategy .............................................................................................. 21 Implementation overview.......................................................................................................................21 Implementation plan development .........................................................................................................21 Implementation activities .......................................................................................................................21 Implementation activities table ...............................................................................................................22
Reasonable assurances ............................................................................................................................24 Adaptive management ............................................................................................................................24 Monitoring strategy

............................................................................................................................... .24



### Potential Funding Sources ............................................................................................................ 26

References Cited ........................................................................................................................... 27

Appendix A

............................................................................................................................... .... 29

Appendix B

............................................................................................................................... .... 31

Mission Creek Watershed DDT TMDL Page i Water Quality Improvement Report

# List of Figures

Figure 1: Map of the Mission Creek Watershe d including Yaksum Creek and Brender Creek ... 4

Figure 2: Stream flow in liters/Seco nd (l/s) for Mission Creek at Cashmere. ............................... 5

Figure 3: Map of the project area with sampling locations for surface water and sediment sample
site locations ................................................................................................................. 10

Figure 4: Soil sampling site locations for the technical report. ................................................... 11



# List of Tables

Table ES-1: 303(d) listings in the Mission Creek Watershed addressed by this TMDL. .............iii

Table ES-2: t-DDT load reductions presented by this TMDL ....................................................... iv

Table 1: Water quality criter ia to protect aquatic life and human health from DDT and its breakdown products. ....................................................................................................... 6

Table 2: Mission Creek Wate rshed waterbodies on the 2004 303( d) List for DDT, DDE, and

DDD.

............................................................................................................................... . 7

Table 3: Conventional parameters in surface water and shallow ground water. ......................... 13

Table 4: Concentrations of DDT (ng/l) in surface water and shallow ground water. .................. 15

Table 5: Load reductions require d to meet target t-DDT loads in Mission, Brender, and Yaksum
Creeks. ........................................................................................................................... 17

Table 6: Organization of TMDL entities and th eir contributions. (A list of acronyms is provided at the end of the table). .................................................................................................. 23

Page ii Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# Executive Summary

The federal Clean Water Act requires that a tota l maximum daily load (TMDL) be developed for
each of the waterbodies on the 303(d) list. The TMDL identifies pollution problems in the watershed, and then specifies how much pollution needs to be reduced or eliminated to achieve clean water. The Washington State Department of Ecology (Ecology) then works with the local community to develop, (1) an overall approach to control the pollu tion, called the summary implementation strategy, and (2) a monitoring pl an to assess the effec tiveness of the water quality improvement activities.

Ecology conducted this TMDL in order to set ta rgets that, if achieved, will bring 303(d) listed
streams in the Mission Creek watershed into co mpliance with state water quality standards. Table ES-1 shows the 303(d) listed streams in the watershed addressed by this TMDL.

Table ES-1: 303(d) Listings in the Mission Creek Watershed addressed by this TMDL.

Waterbody Parameter Medium Listing IDTownshipRangeSection

Mission Creek 4,4’-DDD Water 34832 23N 19E 04

Mission Creek 4,4’-DDE Water 34826 23N 14E 04

Mission Creek 4,4’-DDE Fish Tissue 8960 23N 19E 04

Mission Creek 4,4’-DDT Water 34829 23N 19E 04

Mission Creek 4,4’-DDT Water 8958 23N 19E 04

Mission Creek 4,4’-DDT Fish Tissue 8959 23N 19E 04

Brender Creek 4,4’-DDD Water 34833 23N 19E 05

Brender Creek 4,4’-DDE Water 34827 23N 19E 05

Brender Creek 4,4’-DDT Water 34830 23N 19E 05

Yaksum Creek 4,4’-DDD Water 34834 23N 19E 09

Yaksum Creek 4,4’-DDE Water 34828 23N 19E 09

Yaksum Creek 4,4’-DDT Water 34831 23N 19E 09



### The Mission Creek watershed is in Water Reso urce Inventory Area (WRI A) 45 which is also
known as the Wenatchee River watershed. The wa tershed is in Chelan County in central Washington State. The Mission Creek watershed drains 93.3 s quare miles (59,712 acres), from the Wenatchee National Forest uplands to the Wenatchee River at the city of Cashmere, Washington.

Brender Creek, Yaksum Creek, and No Name Cr eek are tributaries to Mission Creek. The climate is characterized by mild to severe wi nters with hot, dry summers. Streams in the watershed have high flows following snowmelt in the spring and early summer.

The water quality standard for DDT and DDE in water is 0.59 ng/l and is 0.83 ng/l for DDD. One ng/l equals one part per tril lion (ppt). The study found that total-DDT concentrations in

Mission Creek Watershed DDT TMDL Page iii Water Quality Improvement Report

### filtered and unfiltered surface water ranged from 0.1 ng/l to 130 ng/l t-DDT at all sites except in
Mission Creek above the Wenatch ee National Forest boundary.

The highest t-DDT concentrations were found in lower Yaksum Creek. In order to meet water quality standards, load reductions of t-DDT need to meet the targets presented in table ES-2.

Table ES-2: t-DDT load reductions presented by this TMDL

Stream/Location Harmonic

Mean Discharge (l/s) t-DDT
Criterion

(ng/l) Target
Load (mg/d) Average

t-DDT (ng/l) Current
Load (mg/d) Load
Reduction

(mg/d) Load
Reduction (%)

Mission Creek – 2MC 138 1 12 3.2 38 26 69

Mission Creek – MISSPZ1 97 1 8.4 0.4 3.4 (5.0) (150)

Brender Creek – 3MC 86 1 7.4 11 84 77 91

Brender Creek – BRENPZ1 37 1 3.2 26 83 80 96

Yaksum Creek – near mouth 18 1 1.6 62 96 94 98 

### ( ) = reserve capacity

The TMDL recommendations will be carried out through existing requirements and programs, as well as voluntary measures to reduce soil erosio n in Mission Creek wate rshed and education. Monitoring will measure progress toward water qua lity goals. A water quality implementation plan will be developed within a year after the United States Environmental Protection Agency approves this TMDL.

Page iv Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# Acknowledgements

Many thanks to the participants on the Wenatc hee Water Quality Technical Subcommittee and Wenatchee Watershed Planning Unit for their on going participation, tech nical support, wise suggestions, dedication, and commitment to impr oving water quality and the environment. The Mission Creek Watershed DDT TMDL was develope d through the particip ation and input of
numerous stakeholders from the Wenatchee Wate rshed over several years, many of whom spent countless hours providing information, reviewin g and formulating plan actions, and attending meetings to represent th eir constituencies.

Mission Creek Watershed DDT TMDL Page v Water Quality Improvement Report

### Page vi Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# Introduction

The Clean Water Act established a process to id entify and clean up pollute d waters. Under the Clean Water Act, each state is required to have its own water quality standards designed to protect, restore, and preserve wa ter quality. Water quality standa rds consist of designated uses for protection, such as cold water biota and drinki ng water supply, as well as criteria (usually numeric criteria) to achieve those uses.

Every two years, states are required to prepare a list of waterbodies – lake s, rivers, streams, or marine waters – that do not meet water quality standa rds. This list is call ed the 303(d) list. To develop the list, the Department of Ecology (Eco logy) compiles its own water quality data along with data submitted by local, state, and federal governments, tribes, industries, and citizen monitoring groups. All data are reviewed to ensu re that they were collected using appropriate
scientific methods before it is used to develop the 303(d) list. The 303(d) list is part of the larger Water Quality Assessment.

The Water Quality Assessment is a list that tells a more comple te story about the condition of Washington’s water. This list divides waterbodies into one of five categories:

Category 1 – Meets standards for para meter(s) for which it has been tested

Category 2 – Waters of concern

Category 3 – Waters with no data available

Category 4 – Polluted waters that do not re quire a Total Maximum Daily Load (TMDL)
because:
4a. – Has a TMDL approved and it is being implemented 4b. – Has a pollution control program in place that should solve the problem 4c. – Is impaired by a non-pollutant su ch as low water flow, dams, culverts

Category 5 – Polluted waters that require a TMDL – the 303d list.

Washington’s 303(d) list consists of those waterbodies that fall into Category 5 in the Water Quality Assessment process.

Mission Creek Watershed DDT TMDL Page 1 Water Quality Improvement Report

### Page 2 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# TMDL Process Overview

The Clean Water Act requires that a TMDL be developed for each of the waterbodies on the 303(d) list. The TMDL identifi es pollution problems in the watershed and then specifies how much pollution needs to be reduced or eliminated to achieve clean water. Then Ecology works with the local community to develop an overa ll approach to control the pollution, called the summary implementation strategy, and a monitoring plan to assess effect iveness of the water quality improvement activities. Once the United States Environmental Protection Agency (EPA) approves the TMDL, a w ater quality implementation plan (WQIP) should be developed within one year. The WQIP identifies sp ecific tasks, responsible part ies and timelines for achieving
clean water.

This TMDL submittal is based on work presented in DDT Contamination and Transport in the Lower Mission Creek Basin, Chelan County (Serdar and Era Miller, 2004) which will be referred to as the technical report.



## Elements required in a TMDL

The goal of a TMDL is to ensure the impaired water will attain water quality standards. A TMDL includes a written, quantitative assessment of water quality problem s and of the pollutant sources that cause the problem. The TMDL determines the amount of a given pollutant that can be discharged to the waterbody and still meet st andards (the loading capacity) and allocates that load among the various sources. This allocati on was published in the technical report. The Wenatchee Watershed Planning Unit’s (WWPU) Water Quality Technical Subcommittee (WQTS) reviewed the te chnical report twice.

If the pollutant comes from a discrete source (refe rred to as a point source ) such as a municipal or industrial facility’s discharge pipe, that facility’s share of the loading capacity is called a
wasteload allocation . If the pollutant comes from a diffu se source (referred to as a nonpoint source) such as urban, residentia l or farm runoff, the cumulative share of diffuse source inputs is
called a load allocation

.

The TMDL must also consider seasonal variations and include a margin of safety that takes into account any lack of knowledge about the causes of the water quality pr oblem or its loading capacity. A reserve capacity for future loads from growth pressures may be included. The sum of the wasteload and load allocations, the margin of safety, and any reserve capacity must be equal to or less than the loading capacity.

Identifying the contaminant loadi ng capacity for a waterbody is an important step in developing a TMDL. EPA defines the loading capacity as “t he greatest amount of loading that a waterbody can receive without violating water quality st andards” (EPA, 2001). The loading capacity provides a reference for calculating the amount of pollution reduction needed to bring a waterbody into compliance with standards. The portion of the receiving water’s loading capacity assigned to a particular source is a load alloca tion (LA) or wasteload allocation (WLA). By definition, a TMDL is the sum of the allocations , which must not exceed the loading capacity.

Mission Creek Watershed DDT TMDL Page 3 Water Quality Improvement Report

### TMDL = loading capacity = sum of all WLAs + sum of all LAs + margin of safety This TMDL does not present WLAs because there are no point sources in the Mission Creek
watershed that contribu te dichloro-diphenyl-trichloroethane (4,4’-DDT) or its breakdown products, dichloro-diphenyl-dichloroethane ( 4,4’-DDD) and dichlor-diphenyl-ethane (4,4’- DDE).

In this TMDL, 4,4’-DDT, 4,4’-DDD, and 4,4’-DDE are referred to as DDT, DDD, and DDE. The result of adding the concentrations of DDT, DDD, and DDE is referred to as total DDT (tDDT).



## Background

The Mission Creek watershed is located within the Wenatchee River watershed (WRIA 45) in Chelan County near the central part of the state of Washington (State). The Mission Creek watershed drains 93.3 square miles (59,712 acres), from the Wenatchee National Forest uplands to the Wenatchee River at the city of Cashmere . Figure 1 presents a map of the watershed.

Figure 1: Map of the Mission Creek Watershed including Yaksum Creek and
Brender Creek



### Page 4 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

### Brender Creek, Yaksum Creek, and No Name Cr eek are tributaries to Mission Creek. The climate is characterized by mild to severe wint ers with hot, dry summers. Streams in the watershed have high flows following snowmelt in th e spring and early summer. Flows naturally decline to minimums during the la te summer and fall. During the summer critical season, stream flows dry up downstream from some irrigation diversions used dur ing the critical season. Figure 2 presents stream flow data for Miss ion Creek at Cashmere from 1996 through 2004.

Figure 2: Stream flow in Liters/Second (l/s) for Mission Creek at Cashmere.



### The Wenatchee River Watershed Action Plan (W RWAP 1998) notes that soils in the valley bottoms differ significantly among Mission Cree k (gravelly), Yaksum Creek (loamy sand to sandy loam), and Brender Creek (clayey, silt y, and sandy loams). The WRWAP identified Mission Creek as the most pollu ted waterbody in the watershed.

Outside of forested lands, pear and apple orchards make up the primary land use in the watershed along with some alfalfa and non-commercial farms. Orchards flank Mission Creek in a narrow band from the urban boundary of Cashmere to near the Wenatch ee National Forest boundary. Orchards grow in the lo wer portion of Yaksum Cr eek within the confines of the valley that are
cultivatable. Orchards are also located in the Brende r Creek canyon an d are more extensive where the valley broadens on the west side of Cashmere.

DDT was used in Mission Creek Watershed orchar ds to control coddling moths and other pests
from the 1940s to 1970s. EPA banned DDT in 1972. DDT attaches to sediments and particulate matter in the aquatic environment because of its low water solubility and high affinity for solids, especially solids w ith high organic carbon content. Transport of DDT to streams and movement within aquatic environments is often associated with erosion of contaminated soils and elevated loads of suspended solids (Johns on et al., 1988; Joy and Patterson, 1997). DDT and its breakdown products continue to be present at relatively high c oncentrations in the streams of

Mission Creek Watershed DDT TMDL Page 5 Water Quality Improvement Report

### the lower Mission Creek Watershed. Since DDT can remain stable for decades when bound to soils (Harris et al., 2000), it is likely that orchard so ils are the major source.



## Applicable water quality criteria

The state of Washington’s water quality standards for surface waters of the state are set in Chapter 173-201A of the Washington Administrative Code (WAC).

Chapter 173-201A-240 WAC includes a provision that “Toxic substances sh all not be introduced above natural background levels in waters of the state which have the potential either singularly or cumulatively to adversely affect characteristic water uses, cause acute or chronic toxicity to the most sensitive biota dependent upon those wa ters or adversely affect public health as determined by the department.” Numeric criteri a to protect aquatic life from DDT exposure are set to protect the most sensitive aquatic species (EPA, 1980). The chronic criterion for DDT is 1 nanongram per liter (ng/l) – a conc entration not to be exceeded as a 24-hour average (Table 1). One ng/l equals one part per tril lion (ppt). The acute criterion – not to be exceeded at any time – is three orders of magni tude higher at 1,100 ng/l.

Table 1: Water quality criteria to protect aquatic life and human health from DDT and its breakdown products.

Parameter Aquatic Life –
Chronic a

(ng/l) Aquatic Life –
Acute b (ng/l) Human Health – Fish Tissue

(ng/g) c Human Health d

– Water and Organisms (ng/l)

4,4’-DDE 1 1,100 32 0.59

4,4’-DDD 1 1,100 45 0.83

4,4’-DDT 1 1,100 32 0.59

t-DDT 1 1,100 ne ne

a Not to be exceeded as a 24-hour average

b Not to be exceeded at any time

c ng/g = nanograms per gram, equal to parts per trillion in fish tissue

d For consumption of organisms and water
ne = not established



## Human health criteria

Criteria for the protection of huma n health are applied to the stat e through a federal rule [40 CFR 131.36(14)]. In fresh waters, human health criteria take into account the combined exposure of both drinking the water and eating fi sh that lived in the water. In marine waters, human health criteria only consider the effect of eating fish that lived in th e water. The state established criteria to protect against non-carci nogenic illness and to keep the risk of developing cancer to a pre-specified level. In Washington, the cancer risk is set such that no more than 1 in 1,000,0000 people with full exposure would be likely to develop cancer in response to that exposure. Full exposure is defined by set assumptions on body size, fish, and water consumption, and the number of years exposed. For example, in Washi ngton the risk is correlated to an average-sized man consuming 6.5 grams per day of fish (approx imately 5 pounds per year), drinking 2 liters of water (if a fresh waterbody), and continuing this pattern for 70 ye ars. People with higher or lower exposure patterns would face higher or lowe r risks. This basic exposure pattern is the same for both cancer-causing and non-cancer-causing chemicals.

Page 6 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

### In 1992, the EPA published the National Toxics Rule (NTR, 40 CFR 131.36) which set numeric, chemical-specific water quality cr iteria for priority pollutants in order to bring states into compliance with the Clean Water Act.

Acceptable fish tissue concentrations are 32 nanograms per gram (ng/g) for DDE and DDT, and 45 ng/g for DDD. One ng/g is equal to one part per billion (ppb). The NTR uses a bioconcentration factor of 53,600 (EPA, 1980) to translate the acceptable tissue c oncentrations into criteria for water (the tissue concentration times the bioconcentration factor equals the water quality criterion) – 0.59 ng/l for DDE and DDT, and 0.83 ng/l for DDD.



## Water quality and resource impairments

Table 2 shows the 303(d) listings for DDT, DDD, an d DDE in the Mission Cr eek watershed. The current (2002/2004) listings are for exceedances of the human health criteria of DDT compounds (DDE, DDT, and DDD).

Table 2: Mission Creek watershed waterbodies on the 2004 303(d) list for DDT, DDE, and DDD

.

Waterbody Parameter Medium Listing IDTownshipRangeSection

Mission Creek 4,4’-DDD Water 34832 23N 19E 04

Mission Creek 4,4’-DDE Water 34826 23N 14E 04

Mission Creek 4,4’-DDE Fish Tissue 8960 23N 19E 04

Mission Creek 4,4’-DDT Water 34829 23N 19E 04

Mission Creek 4,4’-DDT Water 8958 23N 19E 04

Mission Creek 4,4’-DDT Fish Tissue 8959 23N 19E 04

Brender Creek 4,4’-DDD Water 34833 23N 19E 05

Brender Creek 4,4’-DDE Water 34827 23N 19E 05

Brender Creek 4,4’-DDT Water 34830 23N 19E 05

Yaksum Creek 4,4’-DDD Water 34834 23N 19E 09

Yaksum Creek 4,4’-DDE Water 34828 23N 19E 09

Yaksum Creek 4,4’-DDT Water 34831 23N 19E 09



### The technical report (Appendi x A) presents data on DDE, DDD, and DDT as individual
contaminants. Each of these contaminants e xhibits similar chemical and toxic properties. Implementation actions to address each individual contaminant will be the same. For this reason, implementation of this TMDL addresses the contaminants as t-DDT.



## Seasonal variation

This TMDL report considers seasonal variati on by using calculated loads from pooled
2000-2003 flow data collected over th ree seasons. Current loads cal culated from these data are

Mission Creek Watershed DDT TMDL Page 7 Water Quality Improvement Report

### considered representative of seasonally-adjusted average flow conditions since they were collected under flow regimes ± 25 percent of average.



## Stormwater

Currently, no municipalities are permitted to discharge stormwater by the Phase I or Phase II municipal stormwater permit. Stormwater from urban and rural areas in the project area is considered a nonpermitted, nonpoint source of poten tial pollution. Activities covered by the
state’s construction or industrial stormwater permits should comply with practices identified in the Eastern Washington stor mwater manual (Ecology, 2004).

Data were not collected during rainfall events. St ormwater events may cause episodic loading of t-DDT. By setting daily TMDL targets to meet human health criteria fo r chronic exposure on a daily basis, it is assumed that the acute criteri a will also be met. Water column concentrations measured during the present and pr evious studies were one to thr ee orders of magnitude less than the acute water quality criterion. Ecology recommends that the implementation plan should
include a characterization of t-DDT in st ormwater discharge into surface water.

Page 8 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# Technical Analysis

Study design

Ecology collected samples in April through June 2003. The Quality Assurance Project Plan for this project (Serdar and Era-Mi ller, 2003) describes the sampling and analysis plan designed to meet the project objectives. Th e following various types of sa mples were collected to assess transport of t-DDT to streams and to a ssess movement of t-DDT in the streams.

• Upland soils were analyzed to assess whet her t-DDT is sequestered at significant concentrations in representative orchard la nds and public areas such as schools and city parks.

• Bed sediments were collected from depositi onal areas to assess the degree to which
sediments act as an aquatic sink for t-DDT.

• Suspended particulate matter (SPM) was analyz ed for t-DDT to assess the proportion of
water column concentrations and lo ads contained in the solid phase.

• Filtered and unfiltered water column samples were collected from the creeks to assess the influence of the solid and dissolved component.

• Shallow groundwater was sampled to assess it as a potential t-DDT transport mechanism.

Although the study design included pl ans to collect stormwater r unoff to assess transport of upland soils to streams, these samples were neve r obtained due to logistical problems and a drier than normal spring (precipitation was 30 percen t below normal during the 3-month study period).



## Sample locations

Ecology selected stream sample locations (Figure 3) based on the type of data desired. Project field staff collected water samples and SPM at str eam mouths to assess the total loading and at groundwater sampling locations to assess simila rity between surface water and groundwater. Staff also collected groundwater samples based on availability of groundwater in piezometers. Staff collected bed sediments where fine depositi onal material was available. Accessibility was a factor in selecting all sampling locations.

Field staff collected upland soil samples from fi ve orchards each in the Mission Creek watershed and Yaksum Creek watershed, and from three or chards in the Brender Creek watershed. To decide which orchards to sample, staff gather ed lists of addresses on road segments running alongside orchards. A list of parcel owners provided by the Chelan County Assessor’s Office was then cross-matched against these addresses. Parcel owners were telephoned in a sequence designed to avoid collecting samp les on consecutive parcels. Landowners were informed of the study and asked for permission to sample. If permission was granted, staff asked landowners about the history of the parcels. Parcels that did not have orchards between the early 1950s and
mid-1960s were eliminated from consideration as were parcels that had undergone major soil
disturbance or conversion to othe r land uses. Locations are not s hown in order to preserve the anonymity of private land owners.

Mission Creek Watershed DDT TMDL Page 9 Water Quality Improvement Report

### Upland soils were also collected from five public spaces: three ball fields, and two small city parks (Figure 4). Sites were selected following consultation with the Cash mere School District and the City of Cashmere to ensure soils were native or had been relatively undisturbed in the previous 50 years, and that the la nd had not been used as orchards or for other agriculture in the previous 50 years.

Figure 3: Map of the project area with sampling locations for surface water and sediment sample site locations



### Page 10 Mission Creek Watershed DDT TMDL Water Quality Improvement ReportFigure 4: Soil sampling site locations for the technical report.



## Data analysis

Statistical analysis was conducted using SYSTAT ® 9.01 (SPSS, Inc.). A complete discussion of the statistical analysis can be read in the technical report (Appendix A).

Instantaneous loads of t-DDT were calculated using the following equation.

instantaneous load (mg/day) = IC w 

### x (10 -6 

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

Where:

• IC w 

### = instantaneous concentration of t-DDT in unfiltered water (ng/l)

• IQ = instantaneous discharge in l/s.

• mg/day = milligrams per day

• mg/ng = milligrams per nanograms

• s/day = seconds per day

Mission Creek Watershed DDT TMDL Page 11 Water Quality Improvement Report

## Results

Appendix A presents a complete anal sis and the results for all parame ters investigated as part of this project.



## DDT concentrations in surface water and shallow ground

water

Most of the conventional water quality paramete rs measured during the study appeared to fall into the range of usual values for the streams assessed compared to previous studies. Total organic carbon (TOC) concentratio ns were similar to those prev iously reported by Serdar and Era-Miller (2002). Based on differences between paired unfiltered wate r and filtered samples,
most of the TOC is dissolved at each location.

Flows in Mission Creek were typical for the s easons; however, Brender and Yaksum creeks had flows substantially below norma l (WRWSC, 1998; Serdar and Er a-Miller, 2002). The April 10, 2003, Yaksum Creek discharge measurement may unde restimate actual condi tions but very low
water levels made it difficult to obtain accurate measurements.

DDT concentrations in unfiltered and filtered surface water ranged from 0.1 to 130 ng/l t-DDT, except at Mission Creek above the Wenatchee Na tional Forest boundary (sample location 11MC, Figure 3), where no DDT was detected (Table 4).

• The highest DDT concentrations in surface water were from the lower Yaksum Creek sites (7AMC and 7MC). t-DDT in unfiltered water across sites were composed of 54 percent 4,4’-DDE, 30 percent 4,4’-DDT, and 16 percent 4,4’-DDD on average.

In Yaksum Creek, t-DDT concentrations increased markedly – up to an order of magnitude – downstream of sample locationYAKPZ1. Results also suggest that Yaksum Creek entrains substantial particle-bound DDT in the relatively short reach between 7AMC and 7MC, although there are no paired samples to support this.

t-DDT concentrations in Mission Creek show an increase between MISSPZ1 and 2MC (Figure 3). The confluence of Yaksum Creek and Mi ssion Creek, which is located between MISSPZ1 and 2MC, probably accounts for the increased t-DDT concentrations between these sites.

Brender Creek t-DDT concentrations were inte rmediate with respect to Yaksum and Mission creeks. Unlike the other streams, however, t-DDT concentrations in Brender Creek decreased between the upstream (BRENPZ1) and downstream (3MC) stations. The Peshastin irrigation spill sampled upstream of BRENPZ1 had a t-DDT concentration an order of magnitude lower
than unfiltered water at BRENPZ1.

The BRENPZ1 t-DDT composition was similar to other sites, but unfiltered water from 3MC had an unusual “fingerprint” co mposed of much higher 4,4’-DDD concentrations compared to other sites (31 percent versus 14 percent). Aside from one sediment sample in Yaksum Creek, the only other samples collected for this study with the “high 4,4’-DDD fingerprint” were bottom
sediments and SPM from 3MC.

Page 12 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

### Approximately 20 to 80 percent of t-DDT was in the dissolved form, based on results of paired unfiltered water and filtered water samples. Miss ion Creek (2MC) paired samples indicate that 25 percent of the t-DDT was in the dissolved phase, which agrees well with the calculated dissolved fraction from the SPM sample (28 per cent). In Brender Creek, however, dissolved tDDT fractions calculated from pa ired sample analysis was in poor agreement with SPM (73 percent and 0 percent, re spectively). The high dissolved frac tion was probably due to poor total suspended solids (TSS) removal efficiency by the centrifuge used for Brender Creek.

No DDT was detected in groundwater samples co llected from the Mission and Yaksum Creek sub-basins, suggesting that DDT is not trav eling through groundwater in either gaining (Yaksum) or losing (Mission) reaches. However, the groundwater sampling for this project was limited and may not represent all potential groundwater pathways in the lower Mission Creek basin. Information obtained after sampling show s that there is a large groundwater input to Brender Creek in reach river mile (RM) 1.1- 1.5. Absent any significant DDT load from groundwater, this input could account for the dilu tion in DDT concentrations between BRENPZ1 and 3MC. This reach was not sampled during th e present study but should be considered for sampling in any subsequent su rveys of DDT in groundwater.

Table 3 shows conventional parameters in surfa ce water and shallow groundwater. DDT results are presented in Table 4.

Table 3: Conventional parameters in surface water and shallow ground water.

Location Sample Type Date Discharge (l/s) TSS (mg/l) SS (ml/l/hr) TDS (mg/l) TOC (mg/l)
Mission Creek
2MC Unfiltered

water 4/9-10/03 1,048 18
0.4 U n/a
2.4
“ “ 5/29/03 920 19 0.4 U n/a 1.4
“ “ 6/24/03 328 4 0.1 UJ n/a 1.4

2MC Filtered water 4/9-10/03 1,048 n/a n/a 148 2.4

“ “ 6/24/03 328 1 U n/a 138 2.4

MISSPZ1 Unfiltered

water 5/29/03 n/a 11
0.4 U n/a
1.5
“ “ 6/24/03 n/a 3 0.1 UJ n/a 1.3

MISSPZ1 Ground water 5/29/03 n/a 3 n/a 240 J 1.1
“ “ 6/24/03 n/a 1 n/a 225 1.5



### Mission Creek Watershed DDT TMDL Page 13 Water Quality Improvement ReportTable 3: (cont) Conventional parameters in surface water and shallow ground water.

Location Sample Type Date Discharge (l/s) TSS (mg/l) SS (ml/l/hr) TDS (mg/l) TOC (mg/l)
11MC Unfiltered

water 5/28/03 681 7
0.4 U n/a
1.1
“ “ 6/24/03 246 2 0.1 UJ n/a 1.1

Brender Creek
3MC Unfiltered

water 4/9-10/03 67 16
0.4 U n/a
2.6
“ “ 5/29/03 68 18 0.4 U n/a 1.8
“ “ 6/24/03 131 4 0.1 UJ n/a 1.5

3MC Filtered water 4/9-10/03 67 n/a n/a 312 2.3

“ “ 6/24/03 131 1 U n/a 195 2.6

BRENPZ1 Unfiltered

water 5/29/03 n/a 36
0.4 U n/a
2.2
“ “ 6/24/03 n/a 22 0.1 J n/a 1.8

Peshastin Canal
PESHAST1 Unfiltered

water 6/25/03 n/a n/a n/a n/a n/a

Yaksum Creek
7AMC Unfiltered

water 4/10/03 0.2 1 U
0.4 U n/a
2.5
“ “ “ (rep) 0.2 1 0.4 U n/a 2.6
“ “ 6/24/03 16 14 0.1 UJ n/a 1.8
“ “ “ (rep) 16 15 0.1 J n/a 1.6

7AMC Filtered water 4/10/03 0.2 n/a n/a 360 2.3
“ 6/24/03 16 1 n/a 82 3.3

7MC Unfiltered

water 5/28/03 16 47
0.4 U n/a
2.4
“ “ “ (rep) 16 45 0.4 U n/a 2.2

Location Sample Type Date Discharge (l/s) TSS (mg/l) SS (ml/l/hr) TDS (mg/l) TOC (mg/l)

YAKPZ1 Unfiltered

water 5/29/03 n/a 4
0.4 U n/a
2.0

“ “ 6/24/03 n/a 2 0.1 UJ n/a 1.6

YAKPZ1 Ground water 5/29/03 n/a 8 n/a 308 J 1.5
“ “ 6/24/03 n/a 3 n/a 311 1.5

Notes:
Detected values in bold l/s = liters per second
J = estimated concentration
U = undetected at concentration shown
UJ = undetected at esti mated concentration shown n/a = not analyzed



### Page 14 Mission Creek Watershed DDT TMDL Water Quality Improvement ReportTable 4: Concentrations of DDT (ng/l) in surface water and shallow ground water.

Location Sample Type Date 4,4’-
DDE 4,4’-
DDD 4,4’-
DDT tDDT
Mission Creek
2MC Unfiltered water 4/9-10/03 0.3 J 0.3 U 0.1 J 0.4
“ “ 5/29/03 1.3 0.2 J 0.9 2.4
“ “ 6/24/03 1.6 0.5 1.1 J 3.2

2MC Filtered water 4/9-10/03 0.1 J 0.3 U 0.5 U 0.1
“ “ 6/24/03 0.3 J 0.3 UJ 0.3 NJ 0.6

MISSPZ1 Unfilter ed water 5/29/03 0.3 J 0.3 U 0.1 JB 0.4
“ “ 6/24/03 0.4 0.3 U 0.2 J 0.5

MISSPZ1 Ground water 5/29/03 0.3 U 0.3 U 0.5 U n/c

“ “ 6/24/03 0.3 U 0.3 U 0.5 U n/c

11MC Unfiltered water 5/28/ 03 0.3 U 0.3 U 0.5 U n/c

“ “ 6/24/03 0.3 UJ 0. 3 UJ 0.4 UJ n/c

Brender Creek
3MC Unfiltered water 4/9-10/03 2.3 1.0 0.3 J 3.6
“ “ 5/29/03 3.6 2.1 1.3 7.0
“ “ 6/24/03 3.1 2.1 0.8 J 6.0

3MC Filtered water 4/9-10/03 1.6 0.8 0.2 J 2.6
“ “ 6/24/03 1.8 1.2 0.5 J 3.5

BRENPZ1 Unfiltered water 5/29/03 17 4.4 10 31
“ “ 6/24/03 11 3.5 5.1 J 20

UPBREN Unfiltered water 6/ 25/03 n/a n/a n/a n/a

Peshastin Canal
PESHAST1 Unfiltered water 6/25/03 1.8 0.4 1.0 J 3.2

Yaksum Creek
7AMC Unfiltered water 4/10/03 14 5.3 6.0 25
“ “ “ (rep) 12 4.0 5.2 21
“ “ 6/24/03 28 10 17 J 55
“ “ “ (rep) 27 10 24 J 61

7AMC Filtered water 4/10/03 10 3.6 4.2 J 18
“ 6/24/03 9.1 4.1 5.1 J 18

7MC Unfiltered water 5/28/03 62 22 49 133
“ “ “ (rep) 59 22 47 128

YAKPZ1 Unfiltered water 5/29/03 3.5 2.6 5.1 11
“ “ 6/24/03 3.2 2.8 2.1 8.1

YAKPZ1 Ground water 5/29/03 0. 3 U 0.3 U 0.5 U n/c
“ “ 6/24/03 0.3 U 0.3 U 0.5 U n/c



### Mission Creek Watershed DDT TMDL Page 15 Water Quality Improvement ReportTable 4 (Cont) Concentrations of DDT (ng/l) in Surface Water and Shallow Ground Water.

Location Sample Type Date 4,4’-
DDE 4,4’-
DDD 4,4’-
DDT t-DDT

Centrifuge Blank 4/10/03 0.5 0.1 J 0.1 J 0.7
Field Blank 5/29/03 0.3 UJ 0.3 UJ 0.5 UJ n/c

“ 6/25/03 n/a n/a n/a n/a

Filter Blank 6/24/03 0. 3 U 0.3 U 0.5 UJ n/c

Notes:
Detected values in bold
J = estimated concentration
U = undetected at concentration shown
UJ = undetected at esti mated concentration shown
B = concentration shown is less than five times the amount found in an associated laboratory blank NJ = there is evidence that the analyte is pr esent and the concentration shown is an estimate n/c = not calculated n/a = not analyzed
Shaded values exceed criteria



### Page 16 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# Loading Capacity and Load Allocations

Total DDT targets

Ecology selected targets for t-DDT that will protect benefici al uses in the Mission Creek Watershed. Additionally, targets sh ould be interpreted to apply so that water quality standards are met on a daily basis. As discussed in the in troductory sections of th is report, there are two
sets of relevant criteria - one set to protect aquatic life throug h chronic exposure (1 ng/l for DDT metabolites or t-DDT) and another set to protec t human health (0.59 ng/l for 4,4’-DDE and 4,4’- DDT, and 0.83 ng/l for 4,4’-DDD). Both sets of criteria apply in the Mission Creek Watershed. A reasonable, simple, and slightly conservative a pproach is to use the t-DDT criterion of 1 ng/l. Based on the average compositi on of water samples (56 percent 4,4’-DDE, 17 percent 4,4’- DDD, and 27 percent 4,4’-DDT), water with 1 ng/l t-DDT would typically meet the human health criteria. Conversely, selecting the human health criteria as targ ets could theoretically
double the t-DDT concentration before the ta rget was met (0.59 ng/l 4,4’-DDE + 0.83 ng/l 4,4’- DDD + 0.59 ng/l 4,4’-DDT = 2.0 ng/l t-DDT). Both criteria must be met to comply with water quality standards. Meeting the 1 ng/l target fo r t-DDT should result in meeting the human health criteria for DDT, DDE, and DDD.

The percent reduction of DDT loadi ng necessary to meet the t-DDT criteria are called the target loads. Target loads are based on the loading ca pacity of the water body. Target loads for t-DDT were calculated for Mission, Brender, and Yaks um creeks (Table 5). Target loads were calculated using the formula:

Target Load (mg/day) = CC

w 

### x (10 -6 

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

Where:

• CC
w 

### = DDT criterion in unfiltered water (ng/l)

• HMQ = harmonic mean discharge (l/s Harmonic mean discharge for Mission Creek at Cashmere is 138 liters per second (l/s) based on data from May 1996 through April 2004 (no da ta for water years 2000 and 2001). Harmonic mean discharge for Brender Creek at Cashmere is 86 l/s based on data from February 1997 through January 2004 (no data for water years 20 00 and 2001). Yaksum Creek discharge has a
harmonic mean of 18 l/s based on 15 measurements taken by th e Chelan County Conservation District (CCCD) (1995-1996) and Ecology (2000, 2003).

Table 5: Load reductions required to meet target t-DDT loads in Mission, Brender, and
Yaksum Creeks.

Stream/Location Harmonic
Mean Discharge (l/s) t-DDT Criterion

(ng/l) Target
Load (mg/d) Average
t-DDT (ng/l) Current
Load (mg/d) Load
Reduction

(mg/d) Load
Reduction (%)

Mission Creek – 2MC 138 1 12 3.2 38 26 69

Mission Creek – MISSPZ1 97 1 8.4 0.4 3.4 (5.0) (150)

Brender Creek – 3MC 86 1 7.4 11 84 77 91

Brender Creek – BRENPZ1 37 1 3.2 26 83 80 96

Yaksum Creek – near mouth 18 1 1.6 62 96 94 98 ( ) = reserve capacity



### Mission Creek Watershed DDT TMDL Page 17 Water Quality Improvement Report

### The percent reduction load allocat ion for t-DDT presented in Tabl e 5 is calculated based on the harmonic mean discharge. To meet requirements of the Clean Water Act, it is assumed that the percent reduction for each site in the watershe d will apply to the daily time scale and longer so that water quality standards for t-DDT will be met on a daily basis. Table 5 also shows current tDDT loads for each stream using the formula:

Current Load (mg/day) = AC

w 

### x (10 -6 

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

Where:

• AC
w 

### = average concentration of DDT in unfilte red water (ng/l) based on pooled 2000 and
2003 data

• HMQ = harmonic mean (reciprocal of the arithmetic mean of the sum of the reciprocals of a specified set of numbers) discharge (l/s)

Current loads are considered representative of av erage flow conditions since they were collected under flow regimes ± 25 percent of average.

The greatest t-DDT load reductions are required in Yaksum Creek (98 percent reduction) and Brender Creek where >90 percent re ductions are required to meet targ et loads. Mission Creek at MISSPZ1 (see Figure 3) has a reserve capacity (i .e., amount below assimilative capacity) of 5 mg/day, whereas 2MC requires a 69 percent (26 mg/d ay) load reduction to meet its target load. Meeting the target load at 2MC should be achieva ble if the current t-DDT load in Yaksum Creek is reduced by approximately 30 percent. This should be possible even if the load at MISSPZ1 approaches its assimilative capacity.

In Brender Creek, current t-DDT loads at the upstream location (BRENP Z1) and at the mouth (3MC) are nearly equal as are the load reductions re quired to meet targets. The result of meeting the target load at BRENPZ1 could theoretically yield 3 mg/day reserve capacity at 3MC.



## Margin of safety

This TMDL evaluation incorporates the followi ng assumptions which provide a margin of safety.

• The target numerical water qua lity criterion (1 ng/l) is c onservative because at this
concentration human health criteria will be met based on the typical composition of water samples (56 percent 4,4’-DDE, 17percent 4,4’- DDD, and 27 percent 4,4’-DDT). In the present study, all water samples with t-DDT < 1 ng/l met the individual criteria for 4,4’- DDE, 4,4’-DDD, and 4,4’-DDT. Conversely, se lecting the human health criteria as targets could theoretically double the t-DDT concentration before the target was met (0.59 ng/l 4,4’-DDE + 0.83 ng/l 4,4’-DDD + 0.59 ng/l 4,4’-DDT = 2.0 ng/l t-DDT). The target numerical water quality criterion was used to calculate target loads.

• The use of harmonic mean discharges to calc ulate target loads increases the margin of safety since harmonic means are lower than arithmetic means, especially in cases where discharge data have a wide spread. For instance, the harmonic mean discharge in

Page 18 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

### Mission Creek (2MC) is 138 l/s whereas the arit hmetic mean is 658 l/s. Target t-DDT loads calculated using the harmonic and arit hmetic mean flows are 12 mg/d and 56 mg/d, respectively, with the former, more conser vative target used in this assessment.

Mission Creek Watershed DDT TMDL Page 19 Water Quality Improvement Report

### Page 20 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# Summary Implementation Strategy

Implementation overview

The goals of this implementation plan are to:

(1) Provide guidance for reducing and/or preventing the impacts of pollution
sources to water bodies within the Mission Creek Watershed

(2) Provide a strategy to meet water quality standards.

Several milestones in the development of the TM DL are worth noting. Field studies addressing the 303(d) listed parameters were devel oped and conducted by Ecology from 2002-2004, with assistance from the CCCD. Technical analyses of the studies were co mpleted from 2004-2006. Numerous drafts of the technical reports we re reviewed and commented on by the WQTS and WWPU. Ecology responded to the comments and inco rporated them into the technical reports. Scientists conducting the work provided numerous pr esentations and engaged in discussions with the group.

The WQTS and WWPU assisted Ecology with de velopment of this submittal document from 2005-2007. The process included education, outr each, and assistance with media coverage.



## Implementation plan development

This summary implementation strategy (SIS) was developed with input fro m several members of the WQTS. Implementation of many action items published in the final Wenatchee Watershed Management Plan (WWMP) should help lower t- DDT loading to Mission Creek, its tributaries
and the Wenatchee River. Activities fall into on e of three categories: implementation of an existing law or rule; implementation of educatio nal and voluntary measures to protect water quality; and monitoring and repor ting activities related to water quality improvements.



## Implementation activities

The following actions were developed by the WQTS and are based on recommendations from the TMDL technical study, DDT Contamination and Transport in the Lower Mission Creek Basin, Chelan County, Total Maximum Daily Load Assessment (Serdar and Era-Miller, 2004). These activities are published in the WWMP. Adaptive management may identify other
activities that would contri bute to meeting the targets identified in this TMDL.

If implemented, the nonpoint sour ce control activities listed here should address the 303(d) listings for DDT, DDD, and DDE in this TMDL for Mission Creek, Brender Creek, and Yaksum Creek by 2018.

Implementation Action Item #1. Significant reductions in DDT loads may be achieved by preventing bank erosion or by other means of limiting transport of upland soils to streams. Best Management Practices (BMPs) , such as riparian buffers and wetlands, can also filter and uptake DDT from surfa ce and groundwater (Burgoon, 2002). Many BMPs are currently being implemented in the waters hed. BMPs should be continued, refined,

Mission Creek Watershed DDT TMDL Page 21 Water Quality Improvement Report

### and expanded to further reduce erosion, surface runoff, TSS in the water column, and groundwater transport of DDT. BMPs incl ude farm practices, storm water runoff, riparian vegetation planting, or chard conversions, residential practices, riparian buffers, wetlands, etc. These and other appropriate BMP actions BMP and locations should be coordinated by members of the Planning Unit and its committees.

Implementation Action Item #7

. Activities should be identified and undertaken to provide ongoing outreach, education, and te chnical assistance to grower s, streamside landowners, developers, and the general public.

Implementation Action Item #9. Development over old orchar ds is a potential concern. Measures should be implemented to prevent DDT-laden orchard soils, disturbed during construction, from being transmitted to str eams and lakes in the watershed. Language requiring measures to prevent DDT-laden so ils from entering the waterways during and
after construction should be developed by and included in county and municipality development ordinances, growth management plans, and critical area ordinances. The Stormwater Management Manual for Eastern Washington or an equivalent document should be utilized in developing ordinan ces, and guiding municipal, private, and construction stormwater practices.

Specific BMPs should be coordinated between in dividual land owners/land managers and agency staff with proper qualifications to plan BMPs. For example, the CCCD, U.S. Department of Agriculture (USDA) and Natural Resource Cons ervation Service (NRCS) employ staff members that are trained to design c onservation plans for farms.

In addition to these implementation actions fr om the Wenatchee River Watershed Management Plan (WRWMP), the Washington State Departme nt of Agriculture (WSDA) Waste Pesticide Program provides a means to reduce the potentia l for release of DDT contamination to the environment. Annually, the Waste Pesticide Prog ram provides the opportunity for farmers in the
Wenatchee River Watershed to turn in old and unusable pesticides to the WSDA for proper disposal. The collection of concentrate product greatly reduces the potential for additional DDT release to the environment and loading to streams in the Mission Creek Watershed.



## Implementation activities table

The table below contains general suggestions for voluntary and required actions to be made by each
of the entities involved with th e implementation of the Mission Creek Watershed DDT TMDL. Implementation actions will be described in more de tail in the WQIP. Some actions are dependent upon funding and cooperative agreements. Some acti ons are voluntary and others are regulatory. Actions may be subject to change based on the fe edback and responses from potential contributors, ongoing adaptive management, and regulatory requirements.

Page 22 Mission Creek Watershed DDT TMDL Water Quality Improvement ReportTable 6: Organization of TMDL entities and their contributions . (A list of acronyms is provided at the end of the table).

YEAR

Implementation Action
Item Potential Cooperators20082008-16201220132017201820202021

Complete WQIPX

BMPs to reduce DDT transport to surface waters (#1) WQTS, WWPU, CCCD, Ecology, Agriculture, CC, developers, municipalities, other
stakeholdersX

Monitor BMPs and DDT targets (#2) WQTS, WWPU, CCCD, Ecology, Agriculture, CC, developers, municipalities, other
stakeholdersXX

Monitor during rain events, spring thaw, and irrigation (#3) WQTS, WWPU, CCCD, Ecology, other
stakeholdersX

Ground water monitoring (#4) WQTS, WWPU, CCCD, Ecology, other
stakeholdersX

Icicle-Peshastin Irrigation canal DDT monitoring, BMPs (#5) WQTS, WWPU, CCCD, Ecology, IPID, other
stakeholdersX

Irrigation sediment transport, BMPs (#6) WQTS, WWPU, CCCD, Ecology, irrigation districts, other stakeholdersX

Education outreach and technical assistance (#7) WQTS, WWPU, CCCD, Ecology, Agriculture, CC, developers, watershed groups, municipalities, other stakeholdersX

Provide funding and identify monitoring entities (#8) Ecology, WWPU, agencies, other funding entitiesX

Development ordinances (#9) CC, municipalitiesX

Waste Pesticide Program WSDAXXXXXXXX

Collect data at points of compliance Ecology, other stakeholdersXX

Review data and targets EcologyXXX

Implement adaptive management changes EcologyXXXXXX

Water Quality standards

met Ecology and EPA determineX



### Mission Creek Watershed DDT TMDL Page 23 Water Quality Improvement ReportThe following abbreviations are used in Table 6:

BMP Best management practices CC Chelan County CCCD Chelan County Conservation District CDHD Chelan-Douglas Health District DDT dichloro-diphenyl-trichloroethane DNR Department of Natural Resources Ecology Washington State Department of Ecology
EPA Environmental Protection Agency
IPID Icicle-Peshastin Irrigation District WWPU Wenatchee Watershed Planning Unit TMDL Total Maximum Daily Load WQTS Water Quality Technical Subcommittee WSDA Washington State Depa rtment of Agriculture



## Reasonable assurances

This TMDL addresses only nonpoint sources of pollution, so formal reasonable assurance is not required. This TMDL was developed with inte nse collaboration by the Wenatchee Watershed Planning Unit WQTS. Many action items publishe d in the Wenatchee Watershed Management Plan, if implemented, will help control t-DDT tr ansport to surface waters in the Mission Creek Watershed. Monitoring and adaptive management of implementation actions will help direct appropriate actions to reduce t-DDT loading to surface waters of the Mission Creek Watershed.



## Adaptive management

The Mission Creek Watershed DDT TMDL is the result of a partners hip between Ecology and the WWPU and WQTS. Ecology published this TMDL after the WQTS reviewed and commented on the technical report, titled DDT Contamination and Transport in the Lower Mission Creek Watershed, Chelan County Total Maximum Daily Load Assessment

. Additionally, the WQTS help ed develop and review the SIS for this TMDL.

Information presented in this TMDL represents the current state of knowledge regarding DDT in
the Mission Creek Watershed. It is the understa nding of the WQTS that additional studies may be performed to fill data gaps and to determine the effectiveness of implementing actions identified in this SIS or the WQIP.

A WQIP will be developed for this TMDL that will include a monitori ng plan to evaluate implementation measures. If planned implemen tation activities do not produce the expected or required results, Ecology, members of the WQTS, or other entities may choose to perform more studies to identify signif icant sources of t-DDT to the creeks in the study area. The direction of the TMDL may be modified as a re sult of future monitoring results.



## Monitoring strategy

Monitoring is an important part of this implem entation strategy. Monitoring related to this TMDL should track implementation actions and track water quality improvements that result from implementation actions. In addition, mon itoring conducted related to this TMDL should comply with the Water Quality Data Act (WQDA) codified in RCW 90.48.570 through

Page 24 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

### 90.48.590 and Ecology’s Water Quality Program Policy 1-11. Ecology is responsible for effectiveness monitoring programs that determine if TMDL targets are being met. There are many types of monitoring that local government and organizations coul d effectively conduct.

Listed below are action items from the WWMP describing monitoring needs related to this TMDL. These action items are presente d as they are written in the WWMP.

Implementation Action Item #6. Assessments are recommended for all irrigation systems in the watershed to identify any mechanisms that may contribute to sediment transport which are not yet being addressed by BMPs . Actions should be identified and implemented to address the findings.

Implementation Action Item #4. More comprehensive groundwater monitoring should be conducted, including further assessment of th e relationship between surface water, groundwater, and the fate and transport of DDT compounds.

Implementation Action Item #2. A phased monitoring approach should be conducted to
assess the effectiveness of BMPs and DDT-TSS reduction efforts. This may take time to
achieve as TSS loads are reduced and DDT levels are monitored. Implementation Action Item #3 . Evaluation of soil transport to streams should be conducted during large rainfall events when visual observations can be made and/or sections of streams with high sediment runoff and TSS can be isolated. An assessment should be conducted to investigat e if any other events contribut e soil to streams such as spring thaw processes or irrigation practices.

Implementation Action Item #10. Assessments are recommended for stormwater control systems in the watershed to identify any m echanisms that may contribute to sediment transport which are not yet being addressed by BMPs. Actions should be identified and implemented to address the findings th rough a list of prioritized projects.

Implementation Action Item #5. An assessment should be co nducted to investigate if the Icicle and Peshastin canals are transporting DDT. It is not certain how canals may transport DDT since no wastewater enters the systems and most canals are lined. Current irrigation system BMPs should continue that maintain lined canals and limit rapid increased flows during non-emergency situa tions. Lining of any remaining unlined canals should be encouraged. Other BMPs include actions such as irrigation water management, irrigation return drain monitori ng and efficiencies, irrigation spill points where erosion control can be reduced, s poil pile placement, and maintaining canyon crossings.

Ecology will complete an effectiveness monitoring plan and present it in the WQIP, which is due one year after EPA’s approval of this TMDL.

Mission Creek Watershed DDT TMDL Page 25 Water Quality Improvement Report

# Potential Funding Sources

The Wenatchee Watershed Management Plan iden tified Ecology’s grants program as a potential funding source for implementation activities. A va riety of funding source s could be pursued by various members of the WQTS or other stakeholde rs. Listed below is an action item from the WWMP that describes the WWPU’s plans fo r seeking funding sources. A more thorough presentation of funding sources wi ll be presented in the WQIP.

Implementation Action Item #8. The Department of Ecology may provide funding assistance through its grants and loans programs to implement actions and ongoing monitoring. Other funding sources should be identified and applications submitted to provide funding for ongoing activities.

Page 26 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# References Cited

Burgoon, P. and P. Cross. (2002-2004) Manson Lakes Water Quality Assessment: Lake Trophic
Status and DDT and Phos phorus Load Evaluation . Lake Chelan Reclamation District. Grant No. 0200114, administered by the Wa shington State Department of Ecology, Olympia, WA.

EPA (1980) Ambient Water Quality Criteria for DDT U.S. Environmental Protection Agency. Office of Water Regulations and Standa rds, Criteria and Standards Division. Washington, D.C. EPA 440/5-80-038.

EPA (2001) Overview of Current Total Maximum Daily Load – Program and Regulations

. U.S. Environmental Protection Agenc y. www/epa/gov/owow/tmdl/overviewfs/html

Harris, M.J., L.K. Wilson, J.E. Elliott, C.A. Bishop, A.D. Tomlin, and K.V. Henning. (2000) Transfer of DDT and Metabolites from Fruit Or chard Soils to American Robins (Turdus migratorius) Twenty Years after Agricultural Use of DDT in Canada . Archives of
Environmental Contamination a nd Toxicology. Vol. 39, pp. 205-220.

Johnson, A., D. Norton, and B. Yake. (1988) Persistence of DDT in the Yakima River Drainage, Washington . Archives of Environmental C ontamination and Toxicology. Vol. 17, pp. 289-297. Washington State Department of Ecology, Olympia, WA. Publication

No. 88-e17.

Joy, J. and B. Patterson. (1997) A Suspended Sediment and DDT Total Maximum Daily Load Evaluation Report for the Yakima River . Washington State Department of Ecology, Olympia, WA. Publication No. 97-321.

Serdar, D. and B. Era-Miller. (2002) Pesticide Monitoring in the Mission creek Basin, Chelan County . Washington State Department of Ecol ogy, Olympia, WA. Publication No. 02-

03-022.

Serdar, D. and B. Era-Miller. (2003) Quality Assurance Project Plan – Total Maximum Daily Load Study: DDT Contamination and Trans port in the Lower Mission Creek Basin, Chelan County, Washington. Washington State Department of Ecology, Olympia, WA.
Publication No. 03-03-103.

Serdar, D. and B. Era-Miller. (2004) DDT Contamination and Transport in the Lower Mission Creek Basin, Chelan County: Total Maximum Daily Load Assessment . Washington State Department of Ecology, Olympia, WA. Publication No. 04-03-043.

WRWSC. 1998. Wenatchee River Watershed Action Plan. Wenatchee River Watershed Steering Committee. Wenatchee WA

Mission Creek Watershed DDT TMDL Page 27 Water Quality Improvement Report

### Page 28 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# Appendix A

This TMDL’s technical report DDT Contamination and Transpor t in the Lower Mission Creek Basin, Chelan County can be viewed at the following web site:

http://www.ecy.wa.gov/biblio/0403043.html

Mission Creek Watershed DDT TMDL Page 29 Water Quality Improvement Report

### Page 30 Mission Creek Watershed DDT TMDL Water Quality Improvement Report

# Appendix B

Responsiveness Summary to Comments Received During Public Comment Period.

Ecology held a public comment period for this report from May 23, 2007 to June 22, 2007. The public comment period was advertised in the following Chelan County newspapers:

• The Leavenworth Echo

• The Cashmere Valley Record

• The Wenatchee World

Ecology received the following comment during the public comment period:

Re: the most impassioned plea I made many months age regarding clarity and understandability in the DDT report.

Could you state at least once in the report what an ng/l or an ng/g means?

It might be interesting to the public, and informative if we said "parts per trillion" or something that the mind can grasp as being very, very small. An ng/L means nothing.

The public is not being informed, just alarmed, by ng/l.



### Ecology’s response to the comment:

Response: Ecology incorporated your suggestion to the report. The first time we use nanograms per liter (ng/L) in the report and the report’s executive summary, we also state that 1 ng/L is equal to one part per trillion. In addition we adde d that a nanogram per gram is equal to one part per billion in the portion of th e report that ng/g is used.

Mission Creek Watershed DDT TMDL Page 31 Water Quality Improvement Report