Document ID: EPA-HQ-OPP-2005-0061-0183
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-10-20T04:00Z

Pesticide Use and Toxicity Assay in Mission, Brender, and Yaksum Creeks

WRIA 45 WATERSHED PLANNING – SUPPLEMENTAL WATER QUALITY PLANNING 2003

July 15, 2003

Prepared by:

Peter S. Burgoon, Water Quality Engineering Inc.

and

Michael Rickel, Chelan County Conservation District

Table of Contents

  TOC \o "3-3" \t "Heading 1,1,Heading 2,2"  Executive Summary	  PAGEREF
_Toc46082524 \h  3 

Project Overview:	  PAGEREF _Toc46082525 \h  3 

Introduction	  PAGEREF _Toc46082526 \h  3 

Objectives	  PAGEREF _Toc46082527 \h  4 

Methods and Materials	  PAGEREF _Toc46082528 \h  4 

Site Selection	  PAGEREF _Toc46082529 \h  4 

Timing of Sampling Events with Pesticide Applications:	  PAGEREF
_Toc46082530 \h  7 

Sample Collection and Field Procedures	  PAGEREF _Toc46082531 \h  7 

Laboratory Methods and Quality Assurance	  PAGEREF _Toc46082532 \h  8 

Flow and Field Measurements	  PAGEREF _Toc46082533 \h  8 

Toxicology Bioassays	  PAGEREF _Toc46082534 \h  8 

Results and Discussion	  PAGEREF _Toc46082535 \h  9 

Field Water Quality Data	  PAGEREF _Toc46082536 \h  9 

Pesticide and Flow Data	  PAGEREF _Toc46082537 \h  9 

April Sampling Event	  PAGEREF _Toc46082538 \h  9 

May Sampling Event	  PAGEREF _Toc46082539 \h  10 

June Sampling Event	  PAGEREF _Toc46082540 \h  10 

Linear Correlations between DDT and TSS	  PAGEREF _Toc46082541 \h  10 

Bioassay Results and Discussion	  PAGEREF _Toc46082542 \h  18 

Pesticide Use in Mission Basin	  PAGEREF _Toc46082543 \h  19 

Pesticide Transport Mechanisms	  PAGEREF _Toc46082544 \h  20 

Conclusions	  PAGEREF _Toc46082545 \h  22 

Recommendations	  PAGEREF _Toc46082546 \h  22 

References	  PAGEREF _Toc46082547 \h  23 

 

Appendix A Final Report In Situ Studies with Daphnia pulex
_____________________24

Appendix B Bank Erosion Index Study
______________________________________ 27

Appendix C Pesticide Application Records
___________________________________38

Table of Figures

  TOC \t "Caption" \c  Figure 1. Location of sample sites on Mission
Creek	5

Figure 2. Location of sample sites on Brender Creek.	6

Figure 3. DDT and TSS for all Yaksum Creek water samples.	17

Figure 4. DDT and TSS for all lower Brender Creek water samples.	17

 

Executive Summary

Mission, Yaksum, and Brender Canyons have a long history of orchards and
pest control.  DDT was used along these streams in the 1940’s and
1950’s for mosquito control and was a common household product used
during that time.  Historical DDT use continues to impact water quality
in the sub basins.  Conventional organophosphorus pesticides currently
used for pest control also impact water quality and have been found in
excess of surface water quality standards (Serdar and Era-Miller 2002). 
Water fleas, Daphnia pulex, were placed in Mission, Yaksum, Brender, and
Peshastin Creeks to evaluate toxicity of the creeks during spring and
early summer pesticide applications.  Water samples were collected
before and during the toxicity assays.  Samples were analyzed for
selected organophosphorus (Chlorpyrifos, Azinphos methyl, and Diazinon)
and organochlorine (DDT and metabolites) pesticides.  Application
records in the sub basins were collected to help understand
effectiveness of best management practices during the assays and sample
collection.  Peshastin Creek was used as a control since all orchards
surrounding the creek sites use alternative pest control practices.

There were 3 sampling and assay events.  Each time water fleas were
placed in the creeks and water samples were collected.  

There were no significant difference between survival of Daphnia at the
stations above or below the orchards.  Despite lack of significant
toxicity, there were concentrations of DDT, chlorpyrifos, and azinphos
methyl, at concentrations in excess of the state water quality
standards.  Best management practices were reportedly followed in the
application of all pesticides in the sub basins.  Management practices
appeared to keep pesticides out of the creeks at concentrations that
could be directly correlated to mortality of Daphnia. 

Both Brender and Yaksum Creeks had DDT and TSS concentrations in excess
of State water quality standards.  Both appeared to be increased by
discharge of irrigation water into the creeks.  The sedimentation pond
in Brender Creek was downstream of the sampling stations, and should be
evaluated for effectiveness of TSS and DDT removal.  The increase in DDT
and TSS in Yaksum and Brender was most likely the result of erosion that
occurs within the stream channel.  DDT and TSS likely did not originate
from irrigation canals. 

Project Overview:

This report involves the Level 2 water quality assessment for Water
Resources Inventory Area (WRIA) 45, Wenatchee Watershed.  The purpose is
to conduct assessments that will assist the water quality sub-committee
in developing management strategies for pesticide issues in the basin.

The objective is to restore and protect water quality in the Wenatchee
Watershed by providing needed information to effectively implement
actions that will reduce non-point pollution and result in removal from
the 303(d) list.  The assessments will also facilitate improvement of
habitat for Endangered Upper Columbia River Steelhead and Spring
Chinook, as well as Threatened Bull trout.  The pesticide assessment
will help understand transport mechanisms of pesticides and
effectiveness of best management practices on presence of pesticides in
surface waters.  This work was coordinated with Department of
Ecology’s work on TMDLs in the sub basins. 

Introduction

Pesticide monitoring in Mission Creek Basin in 2000 (DOE 2002) found
levels of organophosphorus pesticides in excess of water quality
standards.  These creeks were not placed on the 303(d) list but it was
recommended that toxicity of these pesticides should be evaluated. 
Chlorpyrifos, azinphos methyl, and Diazinon have all been noted to be
highly toxic to aquatic organisms (DOE 2000, Anderson and Davis 2000,
OSU 2003).

Mission Creek Basin is on the 303(d) for 4,4’-DDT, 4,4’-DDE and
listing was recommended for 4,4’-DDD (DOE 2002).  DOE (2002) sampling
in 2000 also found DDT to be correlated with TSS.  In general, high
spring flows had elevated concentrations of DDT and TSS.  Studies in
orchard soils in the Lake Chelan Basin (LCRD 2003) have found that DDT
regularly appears in agricultural drains at concentration in excess of
standards but with very low concentrations of solids.  There also
appears to be seasonal trends.  Apparently the DDT is transported year
round on fine colloidal material.  Additional sampling is necessary to
better understand what portions of DDT may be associated with colloidal
material or larger suspended solids in Mission Creek.

Studies completed and/or in progress will provide the basis for
determination of a Total Maximum Daily Load (TMDL) for DDT in the
Mission Creek Sub-basin.  Once the TMDL has been determined an
implementation strategy to remediate the problem must be adopted by
stakeholders in the watershed.  This assessment, along with concurrent
sampling by DOE, will assist in understanding the next best steps for
implementing management strategies.

Objectives

Objectives of the assessment are:

Determine toxicity of waters in Mission, Brender and Yaksum Creeks to
Daphnia pulex.

Correlate surface water concentrations of Chlorpyrifos, Azinphos-methyl,
and Diazinon to toxicity bioassay.

Evaluate effectiveness of Best Management Practices in reducing amounts
of pesticides in creeks.

Determine relationship between pesticide concentrations (including DDT),
stream flow, suspended solids and total organic carbon and bioassay.

Evaluate transport mechanisms for pesticides (including DDT) in creeks.

Evaluate management practices designed to reduce pesticides in Mission
Creek, Brender and Peshastin Creeks.

Methods and Materials

Site Selection

Sites for surface water samples were selected above and below/within
orchards in the Mission, Brender, and Peshastin Creek sub-basins.  Sites
above orchards were within US Forest Service land in the upper portion
of the drainages.  Locations are shown on Figures 1 & 2.  Station ID and
location relative to orchards are shown in Table 1.  Stations correspond
to those developed during the Wenatchee Watershed Ranking Project
(WRWSC, 1998) and Department of Ecology TMDL efforts (QAPP 2002) in WRIA
45. 

Figure   SEQ Figure \* ARABIC  1 .  Location of sample sites in Mission
Creek

Figure   SEQ Figure \* ARABIC  2 .  Location of sample sites in Brender
Creek

Table 1. Sites above and below orchards for water sampling and
placement of Daphnia Bioassays.

Site ID	Creek in Basin	Location

Sites Below Orchards

	YC01	Yaksum	About 25 yards downstream of culvert under Coates Road

MC02	Mission	About 10 yards upstream of Binder Rd Bridge

BC02	Brender	About 100 yards upstream of end of culvert under Evergreen
Drive

Sites Above Orchards

	BC01	Brender	USFS land about 100 yards upstream of end o Brender Canyon
Rd.

MC01	Mission	USFS land about 20 yards downstream of USFS flow station

PC01	Peshastin	About 20 yards upstream of King Bridge on Peshastin Creek

The majority of farmers in the Peshastin Creek watershed no longer use
organophosphorus pesticides (John Dully, WSU Extension – Wenatchee,
Personal Communication).  There is one farm, about 15 acres, at the
junction of Highways 2 and 97 that uses organophosphorus pesticides. 
The sample station was located approximately one mile upstream from the
farm that will be using some organophosphorus pesticides.  Samples from
Peshastin Creek will be used as a control for orchards that have not
received organophosphorus pesticides for the last year.  Samples taken
above the orchards in USFS land in Mission Creek Sub basin also serve as
controls but may be influenced by spray drift in the canyons.

Timing of Sampling Events with Pesticide Applications:

Samples were collected in April, May, and June.  Collection times were
coordinated around application times for chlorpyrifos on pears and in
April and May, and application of azinphos-methyl on apples in June. 
Field managers (Bob Gix with Blue Star Growers, and Mike Strutzel with
Wilbur Ellis) were consulted weekly for recommendations on when to
sample according to weather and stage of fruit trees.

Sample Collection and Field Procedures

Each sampling time, referred to as a sampling event, consisted of four
days of sampling.  Each event required surface water sampling, flow
measurements, and placement, removal and counting of bioassay organisms,
Daphnia pulex.  Daphnia were in the creeks for about 3 ½ days for each
event.  

Surface Water Samples

Samples bottles were placed at mid-depth of the water column for
collection of each sample.  At the start of each sampling event, one
grab sample was taken at each sampling location.  The April Event
started in the morning, while the May and June events began in the
evening.  The first and second days of sampling, water samples were
composited throughout the day from each site.  When samples were
composted, a 125 mL bottle was used to collect the sample, which was
then placed in the 1L composite bottle.  On the third day, composited
samples were only collected at the sites below the orchards (Table 2). 
The composited samples was kept in a cooler and shipped to a laboratory
for analysis at the end of the day.  Table 3 presents the sample bottle
type, holding time, and preservation.

Table 2. Daily Sample collection during a sampling event.

Sampling locations	Site ID	Night Before	Day 1	Day 2 	Day 3	Total Samples

Mission above orchards	MC01	1	1	1

Mission below orchards	MC02	1	1	1	1

	Above Brender orchards	BC01	1	1	1

Brender below orchards	BC02	1	1	1	1

	Yaksum below orchards	YC01	1	1	1	1

	Peshastin below orchards	PC01	1	1	1

Field Replicate	MCO1R	1	1

	Total samples

7	7	6	3	23

Table 3. Recommended Sample Containers and Preservation.

Parameter	

Sample Container	

Preservation	Holding Time

Pesticides (DDT and OPs)	Glass/teflon lid liner, 1 L.	4(C	7 days

Total Suspended Solids	Polyethylene, 1 L	4 (C	7 days

Total Organic Carbon	Polyethylene, 60 mL	4(C, H2SO4, <pH 2	28 days

Laboratory Methods and Quality Assurance

Table 4 shows analytical methods and reporting limits for DDT,
organophosphorus pesticides and conventionals.  Organophosphorus
pesticides will be analyzed using gas chromatography with mass
spectrometry with ion trapping (GC/MS/IT).  TSS and TOC will be analyzed
using standard EPA methods.  Sample analyses were conducted by a
laboratory accredited by the State of Washington for analysis of
organophosphorus pesticides.  Cascade Analytical in Wenatchee will be
doing the TOC, TSS, and Turbidity.  Pacific Agricultural Laboratory in
Portland, Oregon will be doing the pesticide analysis.  Pacific
Agricultural Laboratory did not report detection limits below the method
reporting limit for pesticide analysis.  Therefore, pesticide
concentrations below the method detection limit are not presented. 

Bias of the data was assessed through analysis of matrix spikes. 
Surrogate recoveries were used as an indication of systematic error. 
The data quality objective for bias is 50% - 150% recovery of matrix
spikes.  Precision of data was assessed through the analysis of matrix
spike duplicates.  The data quality objective for precision was relative
percent differences (RPDs) <25%.  

Flow and Field Measurements

Continuous recording stream gages are in place in Mission and Peshastin
Creeks.  In Yaksum and Brender Creek, stream flow was measured using the
USGS Stream Gaging Procedure (196) and a Marsh-McBirney, Inc. FlowMate
2000.  Temperature and pH was measured using an YSI Model 60 temperature
compensating pH meter.  Specific conductance was measured using an YSI
Model 30 meter.  Dissolved oxygen was measured with an YSI Model 55
meter. 

Toxicology Bioassays

Laboratory cultures of Daphnia pulex (< 24 hr) were pooled and batches
of ten neonates were randomly transferred into 20-ml culture tubes for
transport to the test sites. Daphnia pulex were transported in the
culture tubes within a cooler with ice to allow D. pulex to acclimate to
test site ambient conditions while traveling to the test sites (2-3
hours). Test chambers are constructed with 125-ml high-density
polyethylene capped bottles. Two squares (6 cm x 6 cm) are cut into the
bottle and covered with 0.160-0.210 mm mesh. This mesh allows water to
flow through the chamber but contains the Daphnia within the cage.

Table 4. Analytical Methods and Required Detection Limits.

Parameter	Method Reporting limits	Expected Range of Results	

Method

Organophosphorus Pesticides

	GC/MS/IT - EPA 8141

Azinphos-methyl, ug/L	0.020	0.001 – 0.043

	Chlopyrifos, ug/L	0.010	0.001 – 0.047

	Diazinon, ug/L	0.016	0.001 – 0.01

Organochlorine Pesticides

	DDT and metabolites, ug/L	0.010	0.001 - 0.05	EPA 8081A

Total Suspended Solids, mg/L	0.5	1-2,000	Gravimetric - EPA 160.2

Total Organic Carbon, mg/L	0.5	1-20	Combustion IR - EPA 415.1

At each study site, three chambers with ten D. pulex neonates were
placed in each chamber.  Chambers were suspended side by side so that
they were in the flow of water. In this way, Daphnia in chambers were
exposed to similar physical conditions, such as light and temperature. 
Chambers remained in the field for about 96 hours depending.  After the
third full day of exposure, the chambers were removed from the creek,
transported to the laboratory, and live Daphnia in the cages were
counted.

Results and Discussion

Field Water Quality Data

Field measurements of pH, temperature, Dissolved Oxygen sample composite
times are shown in Tables 5a, 5b and 5c.  All water samples were
composited during the sampling day.  Field measurements were taken at
the time of sampling.  

Pesticide and Flow Data

April Sampling Event

Chlorpyrifos was measured at sites below orchards in Brender and Yaksum
Creeks at concentrations in excess of the Washington State acute and
chronic water quality standards (AWQS and CWQS respectively) (Table
6a.).  There was no Chlorpyrifos measured in any of the above orchard or
Peshastin Creek samples.  There was no azinphos methyl measured at any
of these sites.  During this sampling event, there was spraying observed
in both the Mission Creek and Brender Creek sub basins.  Chlorpyrifos
was expected during this event since is used in late spring on pears. 
Azinphos methyl is generally not used at this time of year and was not
detected.

DDT was in excess of CWQS on all sampling days at the Yaksum Creek and
lower Brender Creek sites.  DDT was detected on one day at the lower
Mission Creek site.  There was no DDT detected at the above orchards
sites or in Peshastin Creek samples.  DDT detected was at least an order
of magnitude above the CWQS.  Therefore, DDT may have been present at
lower concentrations than detected.  This study did not have detection
capability below the reporting limit of 0.010 ug/L.

The second day, after the start of the April Event, irrigation tail
water diversion to Brender Creek began.  The diversion occurs about
midway between the two Brender Creek sampling stations.  The diversion
caused high flows and turbidity.  A grab sample taken on Day 2 had 248
mg/L TSS.  DDT concentrations were the highest measured at any site
during all sampling events (Table 6a, b,c).  DDT concentration in lower
Brender Creek appear to be influenced by erosion of stream banks.  Flows
increased 2 to 4 times greater than the flow on Brender Creek above the
orchards (Table 6a).  All the DDT concentrations measured in Brender
Creek were greater than samples collected in 2000 by Serdar and Miller
(2002).

May Sampling Event

During the May sampling event, Chlorpyrifos was not measured at any
sites in excess of CWQS.  It was detected on all sampling days in Yaksum
Creek (Table 6b.).  There was no azinphos methyl or Diazinon measured at
any of these sites.  During this sampling event there was no spraying
observed in the basin during sampling.  

Event 2 was done during a normal break in application of pesticides for
the sub basins.  Chlorpyrifos and azinphos methyl were not expected
during this event.  No spraying was observed during the sampling events.

During the May sampling event DDT was in excess of CWQS at the sites
below orchards in Yaksum and Brender Creeks.  DDT detected was at least
an order of magnitude above the CWQS.  Concentrations may have been
present at lower concentration but still above the CWQS.  

June Sampling Event

During the June sampling event, Chlorpyrifos was not measured at any
sites in excess of CWQS (Table 6c.).  Azinphos methyl was detected at
concentrations an order of magnitude greater than the CWQS in Brender
Creek and significantly greater than the CWQS in Yaksum Creek (Table
6c).  No Diazinon was measured at any of these sites in Event 3.  During
this Event spraying was observed in the basin during sampling.

Event 3 was done when applications of azinphos methyl were expected. 
Spraying of Chlorpyrifos should have been complete.  Low concentration
of Chlorpyrifos could be due to spraying of or another transport
mechanism.

During the June sampling event DDT was in excess of CWQS at the sites
below orchards in Yaksum and Brender Creeks.  Both Yaksum and Brender
were receiving irrigation water from the Icicle Irrigation District and
subsequently had high flows and high TSS.  The increase in DDT and TSS
in the streams was most likely the result of erosion that occurred
within the stream channel due to increased flows.  The water samples
with the highest DDT also had the highest TSS in both Brender and Yaksum
Creeks (Table 6c). 

Linear Correlations between DDT and TSS

Linear correlation for DDT and TSS are helpful in understanding how to
remove the solids.  In general, if you can remove TSS then DDT should be
removed.  The linear correlation for DDT and TSS was positive but weak
in both Yaksum and Brender Creeks (Figures 3 and 4).  This is 

Table 5a. Field data for for all Site during April Sampling Event 

Date	Sample Time	Station ID	pH	Temp	DO	Sample composite times	 

4/14/03	Day of Spray	BC01	7.8	7.92	9.8	1315	1700

 

4/15/03	Day 1	BC01	8.02	7	11.13	1140	1440	1645

	 

 	Site average	BC01	7.91	7.46	10.465

 

4/13/03	Night Before	BC02	8.6	11	10.7	1235	 

 

4/14/03	Day of Spray	BC02	8.58	10.9	11.35	1540

	 

4/15/03	Day 1	BC02	8.54	9	12.21	1050	1200

 

4/16/03	Day 2	BC02	8.07	6.9	11.6	945

	 

 	Site average	BC02	8.45	9.45	11.47

 

4/13/03	Night Before	MC01	8.19	7.4	11.88	1430

	 

4/14/03	Day of Spray	MC01	7.89	7.4	11.43	1510

	 

4/15/03	Day 1	MC01	8.3	4.5	11.2	1025	1244	1555

	 

4/13/03	Night Before	MC01 R	8.19	7.4	11.88	1025	1244	1555

	 

4/14/03	Day of Spray	MC01 R	7.89	7.4	11.43	1025	1244	1555

	 

 	Site average	MC01	8.09	6.82	11.56

 

4/13/03	Night Before	MC02	8.6	7.5	12.02	1510

	 

4/14/03	Day of Spray	MC02	8.6	7.5	12.02	1510

	 

4/15/03	Day 1	MC02	8.33	4.7	10.1	940	1100	1215	1320	1525	1620

 

4/16/03	Day 2	MC02	9.4	5.9	12.31	1050	1130	1215	1300	1345	1425	1500	 

 	Site average	MC02	8.73	6.40	11.61

 

4/13/03	Night Before	PC01	nd	nd	nd

 

4/14/03	Day of Spray	PC01	nd	nd	nd

 

4/15/03	Day 1	PC01	nd	7.8	11	1030

	 

 	Site average	PC01	nd	7.8	11	 

	 

4/13/03	Night Before	YC01	8.7	10.4	11.25	1140

	 

4/14/03	Day of Spray	YC01	8.7	10.4	11.25	1510	1620

 

4/15/03	Day 1	YC01	8.69	6.3	10.2	1005	1115	1225	1535	1615

	 

4/16/03	Day 2	YC01	8.75	8.7	11.28	1020	1140	1230	1310	1400	1435	1520	 

 	Site average	YC01	8.71	8.95	11.00	 	 	 	 	 	 	 	 





Table 5b. Field data for for all Site during May Event 

Date	Sample Time	Station ID	pH	Temp	DO	Sample composite times	 

5/19/03	Night Before	BC01	7.8	8	9.5	1800

	 

5/20/03	Day of Spray	BC01	7.83	8.3	10.34	1105	1250	1445	1705

 

5/21/03	Day 1	BC01	7.84	8.5	10.14	1235	1335	1430	1635

 

 	Site average	BC01	7.82	8.27	9.99

 

5/19/03	Night Before	BC02	8.6	11.4	11	1100

	 

5/20/03	Day of Spray	BC02	8.2	11	10.4	1045	1125	1235	1310	1430	1505

 

5/21/03	Day 1	BC02	8.22	12.4	10.26	1038	1225	1252	1320	1415	1615

 

5/22/03	Day 2	BC02	8.2	11.8	10.5	1015	1110	1135	1205	1250	1430

 

 	Site average	BC02	8.31	11.65	10.54

 

5/19/03	Night Before	MC01	7.8	7.7	10.7	1730

	 

5/20/03	Day of Spray	MC01	8.17	8.7	11.02	1020	1200	1340	1630

 

5/21/03	Day 1	MC01	8.17	8.7	11.02	1000	1155	1300	1335	1450

	 

5/19/03	Night Before	MC01 R	7.8	7.7	10.7	1730	 

 

5/20/03	Day of Spray	MC01 R	8.17	8.7	11.02	1020	1200	1340	1630

 

5/21/03	Day 1	MC01 R	8.17	8.7	11.02	1000	1155	1300	1335	1450

	 

 	Site average	MC01	8.05	8.37	10.91

 

5/19/03	Night Before	MC02	8.6	10.8	11	1630

	 

5/20/03	Day of Spray	MC02	8.2	9.4	11.17	945	1130	1225	1320	1420	1600

 

5/21/03	Day 1	MC02	8.25	10.4	10.86	930	1030	1105	1220	1410	1600

 

5/22/03	Day 2	MC02	8.2	9.7	10.3	930	1045	1120	1215	1310

	 

 	Site average	MC02	8.31	10.08	10.83

 

5/19/03	Night Before	PC01	nd	7.7	12	1030

	 

5/20/03	Day of Spray	PC01	nd	9.1	nd

 

5/21/03	Day 1	PC01	nd	nd	nd

 

 	Site average	PC01	#DIV/0!	8.4	12.00

 

5/19/03	Night Before	YC01	8.6	10.8	11	1700

	 

5/20/03	Day of Spray	YC01	8.19	11.1	10.44	1000	1140	1220	1325	1405	1610

 

5/21/03	Day 1	YC01	8.25	12.2	10.43	938	1025	1115	1230	1425	1435

 

5/22/03	Day 2	YC01	8.21	11.2	11.7	955	1055	1125	1225	1340

	 

 	Site average	YC01	8.31	11.33	10.89	 	 	 	 	 	 	 	 



 

 

due to the presence of DDT in samples with low concentrations of TSS,
conversely TSS is often present with low DDT (Table 6a,b,c).

Bioassay Results and Discussion

The average survival of Daphnia in all events and sites above the
orchards was 82 ± 12% compared to 81 ± 29% for sites below the
orchards (Table 7).  During all events concentrations of pesticides in
the creeks did not appear to influence survival of the Daphnia (Table
7).  During Event 1, Chlorpyrifos was present in Brender and Yaksum
Creek at concentrations significantly greater than the CWQS and AWQS
(Table 6a).  The water samples were composites and imply exposure
throughout the sampling day.  The high concentration may not have caused
mortality because the pesticides were adsorbed to sediment.  During
Event 3, Azinphos methyl was present in Brender and Yaksum Creek at
concentrations significantly greater than the CWQS and AWQS (Table 6c).

 

Previous studies have shown high mortality of Daphnia with chlorpyrifos
concentrations in the ranges measured in Event 1 (Anderson and Davis
2000).  The high mortality measured by Anderson and Davis (2000) had
concentrations of Chlopyrifos similar to this study but also had
Diazinon level 2 – 20- times higher than measured in this study. 
California Fish and Game have a water quality criteria for Diazinon of
0.04 ug/L, versus concentrations of 0.87 to 7.0 measured in the
cranberry bogs by Anderson and Davis (2000).  Diazinon was detected only
on two sampling days on lower Brender Creek in Event 1 (Table 6a).  The
concentrations were in excess of the California Fish and Game standard
of 0.04 ug/c

There was unusually high mortality in Yaksum Creek on Event 2 and in
Peshastin Creek on Event 3 (Table 7).  The very high mortality seen in
Yaksum Creek and Peshastin Creek appeared to be anomalies, probably due
to high flows.  The high mortality at Yaksum Creek may have occurred due
to placement below an irrigation return pipe that was not in use prior
to the placement of the Daphnia (Table 6b and 7). The complete mortality
in Peshastin Creek during Event 3 may have been due to peak spring flows
during the week of the study (Table 6c and 7). 

A report by Dr. John Stark (WSU Puyallup) is provided in Appendix A. 

Pesticide Use in Mission Basin

Of the approximately 1,403 acres of fruit orchards in the Mission,
Brender and Yaksum drainages (Chelan County Conservation District,
1996), approximately 85% is pears, 12% is apples and 3% cherries (Bob
Gix, Field Representative for Blue Star Growers – Cashmere, Personal
Communication).

The goal of pest management is the regulation of damage caused by pests,
taking into account both costs and benefits of control procedures.  Pest
management must be compatible with current production practices and
short-term profitability, but it strives to develop strategies that lead
to long-term, stable and cost-effective management programs.  The
potential benefits of pest management include reduced chances of pest
resurgence, slower development of resistance to pesticides, lower
pesticide application costs, and reduced environmental contamination. 
The costs include management time, monitoring, and possibly more
expensive control procedures.  

In general, there is a “two-stage” (pre and post bloom) method of
controlling pests in orchards.  If pest populations are kept in control
during the first stage (pre-bloom, typically in March and April) of
fruit development then less treatment is required during the second
stage of development (post bloom, typically in May).  The two stage
“fight” is especially true for pears.  The main products used for
pears during the first stage include horticultural mineral oil plus one
of the following:  endosulfan (Thiodan), esfenvalerate (Asana), lime
sulfur, flowable/microized sulfur, kaolin clay (Surround), and diazinon.
 Products used in the second stage include; Isomate-C Plus, terramycin,
Success, pyriproxyfen, abamectin (Agri-Mek) horticultural mineral oil,
thiamethoxam (Actara), acetaminprid (Assail), azinphos methyl (Guthion)
50P, lorsban (Chlorpyriphos) phosmet (Imidan), methoxyfenozide
(Intrepid).  These products are commonly used on apples and cherries as
well.  A list of products applied by drainage is presented in Appendix
C.

Perhaps the simplest of the general recommendations (or Best Management
Practices) for pest management is to closely follow the product label. 
The proper pruning and spacing of trees is an aid in the control of many
insects and disease.  Both proper timing of sprays and thorough coverage
are essential for good control.  Orchard operations differ with regard
to equipment, spacing and size of trees, local weather conditions, and
particular pest problems.  The timing, concentration, and gallonage of
spray per should very accordingly.  A detailed spray program should be
worked out for the orchard based on differences.  Heavy, brief showers
or lighter rain for a longer period or over tree irrigation or fruit
cooling will remove pesticides from fruit and foliage surfaces.  

More specifically, to implement Best Management Practices (BMPs) in an
orchard system:

	•become familiar with insect biology and pest management principles,

	• plan a season and long-term strategy

	• monitor pest populations and use control procedures based on
economic injury 

levels, and

	• keep records and use them to refine the following season’s
strategy.

Integrated Pest Management (IPM), along with BMPs, is the primary
management method for pests in the study area.  Specifically, consistent
monitoring of fruit development and the presence of pests allow farmers
to apply pesticides only when pest populations required it.  BMP’s
also encourage the use of “soft control” methods (i.e., pheromone
traps).  

The primary BMPs for organophosphate pesticides used in the study area
are; no spraying within 300 feet of surface water, not spraying on days
where wind speed is greater than 15 mph or rain is expected, IPM
(scouting and applying pesticides only when needed), and using soft
methods when appropriate.  

 

The effectiveness of Best Management Practices (BMP’s), Integrated
Pest Management and closely following the label directions has proven to
be very successful for treating pests and reducing off site transport of
pesticides.  The primary components of BMPs are scouting (monitoring
pest populations and applying pesticides only when needed) and
Integrated Pest Management (IPM).  IPM is the use of cultural and
biological methods of pest control (the use of pheromones are an
example).  

The spray record obtained from orchardists does not reflect application
of chlorpyrifos or azinphos-methyl during any of the three periods
Daphnia were in the streams.  However, during the first bioassay
(Daphnia in streams) several orchards were observed being sprayed.  It
is anticipated that they were applying chlorpyrifos based on the
concentrations in the streams studied (Table 6a).  Concentrations
approximately twice the state standard was recorded for chlorpyrifos in
Yaksum Creek (YC01) and Brender Creek (BC02).  Regardless of the high
concentrations in these streams, mortality of the daphnia was very low. 

Future use of the organo phosphorus pesticides will most likely be
reduced.  The use of Guthion (Azinphos methyl) will also be
significantly reduced in 2004.  Chlorpyriphos and diazinon will continue
to be used in orchards that are not utilizing softer methods of pest
control.  There is a trend in the region to utilize soft control
methods.    

Pesticide Transport Mechanisms

A variety of pesticides are used on the apples, pears and cherries in
these sub basins.  The transport mechanisms of concern are aerial drift
during spraying, leaching and transport in groundwater and, erosion of
soils with adsorbed pesticides.

Aerial drift during spraying is difficult to quantify but based on field
observation it is the most apparent and possibly significant transport
mechanism into creeks.  Application requirements for pesticides are
established by the Environmental Protection Agency and enforced by the
Washington Department of Agriculture.   The only setback from surface
water for the pesticides evaluated is 25 foot when applying azinphos
methyl.  Many orchards in the sub basins evaluated are less than 50 feet
from the creeks.  Most farmers in the region apply according to the
product label directions and keep excellent spray records.  Pesticide
sampling showed high concentrations of chlorpyrifos and/or azinphos
methyl in both Yaksum and Brender Creeks when spraying was observed in
the field during Events 1 and 3.  Assuming application of pesticides
were following label directions, they were not effective at stopping
drift and transport into the creeks.   

Transport of pesticides into the environment via erosion and leaching is
a function of persistence in the environment.  Persistence depends on
chemical and biological decomposition and potential for leaching. 
Persistence is summarized in Table 8 showing half-life and leaching
potential of the pesticides.  The half-life varies considerably
depending on the environmental conditions.  Both Chlorpyrifos and
Azinphos-methyl have a long enough presence to be leached into the
groundwater during irrigation after pesticide applications.  This
transport mechanism is expected to be low due the low leaching potential
and adsorptive nature of the pesticides.

Table 8. Half-life and leaching potential of pesticides.

	Half life, days	Potential to Leach

	Aerobic	Anaerobic

	Chlorpyrifos	11 – 141	15 – 58	Low

Azinphos methyl	21	68	Low

DDT	15 –20 years	Low

All pesticides of concern are hydrophobic and consequently adsorb to
soils and organic matter.  This basic chemistry also results in low
mobility of azinphos-methyl and chlorpyrifos due to preference for
adsorption to soil and low potential for pollution of groundwater
(Oregon State University 1986, Cornell University 2003).  DDT has
similar hydrophobic characteristics and is commonly found in the upper 1
foot of the horizon in orchards soils (Harris et al. 2000).  DDT has the
longest half-life and it’s presence in creeks is assumed to be due to
use prior to passage of the Clean Water Act in 1972.  

Although leaching potential is low for all these pesticides, leaching
may still occur. 

Previous surface water evaluations in these sub basins have shown some
correlation between DDT and suspended solids, implying that erosion of
soils is a significant transport mechanism (DOE 2002).  In this study
the highest concentration of DDT were found with samples with the
highest TSS concentrations.  The flow, pesticide and TSS data for
Brender and Yaksum Creeks showed elevated TSS and DDT with the higher
flows (Tables 6 a,b,c).  All creeks in the study receive irrigation
bypass water.  The flow extra flows in both Brender and Yaksum appear to
increase TSS concentrations in the creeks.   Although the maximum DDT
and TSS were measured in the same water samples, there was not a strong
correlation for DDT and TSS in the samples overall (Figures 3 and 4).  A
Bank Erosion Hazard Index was determined for all three creeks (Appendix
B).  This predicted that the greatest erosion hazard was in Brender and
Yaksum Creeks.  This supported the high TSS measured in the creeks
during the Events, especially during discharge of irrigation water in
Brender and Yaksum Creeks.  Erosion appears to be a significant
transport mechanism for TSS and adsorbed pesticides in the creeks.

  

Conclusions

Chlropyrifos, Azinphos methyl, and Diazinon have elevated concentrations
in the creeks during pesticide application in Brender and Yaksum Creek. 
The pesticides were not present in Mission Creek at detection limits
available in this study. 

DDT is present at concentrations above the Chronic water quality
standard of 0.001 ug/L in Yaksum and Brender creeks at below orchard
sites.  

DDT and TSS concentration appear to increase in Brender Creek and Yaksum
Creeks due to erosion from irrigation return flows. 

Correlation between DDT and TSS were not strong. Consequently
concentrations of DDT in were often in excess of water quality standards
although associated TSS concentrations were <5 mg/L.

All the Brender Creek samples are collected prior to passage through a
sedimentation pond downstream of Evergreen Road.  The DDT loads from
this study represent what is entering the pond.  The removal in the pond
and net load to Mission Creek was not measured.

Recommendations

The effectiveness of the sedimentation pond on Brender Creek below
Evergreen Road should be evaluated.  The sediment concentrations of DDT
should also be measured.  DDT is a dangerous pesticide because it will
bio-concentrate in aquatic food chains.  Concentrating the DDT in a pond
in the surface sediments increases the chance that it will move through
the ecosystem.  An evaluation of risk and cost to remove the sediments
should be completed. The information could provide information for
improving performance of the sedimentation pond and designing one for
Yaksum Creek.

References

Chelan County Conservation District. 1996.  Wenatchee River Watershed
Ranking Report Addendum – Technical Supplement 1. Wenatchee, WA

Cornell University. 1986. Chemical Fact Sheet for Azinphos Methyl
(Guthion).    HYPERLINK
http://pmep.cce.cornell.edu/profiles/insect-mite/abamectin-bufencarb/azi
nphos-mehtyl 
http://pmep.cce.cornell.edu/profiles/insect-mite/abamectin-bufencarb/azi
nphos-mehtyl .

Oregon State University 2003. Extension Toxicology Network: Pesticide
Toxicology Network – Chlorpyrifos.    HYPERLINK
http://ace.ace.orst.edu/info/extonet/pips/chlorpyr.htm 
http://ace.ace.orst.edu/info/extonet/pips/chlorpyr.htm 

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 Orchard
Soils to American Robins (Turdus migratorius) Twenty Years After
Agricultural Use of DDT in Canada. Archives of Environmental
Contamination and Tocicology 39:205-220.

Serdar and Miller. 2002. Pesticide Monitoring in the Mission Creek
Basin, Chelan County. Washington State Department of Ecology Publication
No. 02-03-022.

Anderson and Davis. 2000. Evaluation of Efforts to Reduce Pesticide
Contamination in Cranberry Bog Drainage.  Washington State Department of
Ecology Publication No. 00-03-041

Lake Chelan Reclamation District. 2003.  Year 1 Report on DDT and
Phosphorus in Manson Lakes.  Unpublished.  Year 1 summary of 2 year
project.  

APPENDIX A

Final Report

June 13th, 2003

In situ studies with Daphnia pulex in streams and rivers in the Cashmere
area of the Chelan Conservation District

Personnel

John Stark, Ph.D. Professor/Scientist

Rachel Johnson, Technician

Susanna Hopkins, Graduate Student

Washington State University

Puyallup, WA 98371

(253) 445-4519

Background

The water flea, Daphnia pulex will be used to monitor water quality by
placing these organisms in flow-through chambers in Mission, Brender and
Peshastin Creeks and monitoring mortality.  Concurrent water sampling
for pesticides will be carried out by the Chelan County Conservation
District. Water Quality Engineering, Inc. and the Chelan County
Conservation District will coordinate with WSU for placement of caged
Daphnia pulex in Mission, Brender and Peshastin Creeks.  The cages will
be put in place one day before the spraying and then monitored by WSU
three days after installation.  The goal is to monitor pesticide
spraying events in fruit tree orchards and determine whether lethal
amounts of pesticides are entering these fresh water systems.  Daphnia
will be placed in situ during the spray period and mortality will be
evaluated at a specified time interval.  An interpretation and summary
of all Daphnia mortality data will be provided to Water Quality
Engineering, Inc. Comparison to water quality data will be a joint
effort between WSU and Water Quality Engineering.

Materials and Methods

In situ studies with the water flea, Daphnia pulex, were conducted in
several streams and a river in the Cashmere area of the Chelan
Conservation district during the months of April, May and June 2003. 
The in situ studies were conducted with concurrent water sampling to
determine the type and amount of pesticides in these freshwater systems.

Two to three flow-through cages, of approximately 300 ml volume capacity
each, were placed at each site.  Each cage consisted of a clear plastic
polyvinyl chloride cylindrical tube (15 cm long, 7 cm external diameter)
with two rectangular windows (9 cm x 4 cm) cut out and covered with a
micromesh screen so that the water could flow through the cage but the
Daphnia could not get out of it.  The ends of the cages were sealed with
slide-on plastic caps.  The D. pulex neonates (24 hours old or less)
were transported to the field sites in groups of ten in the cages
submerged in laboratory water in a cooler.  Cages containing the Daphnia
were suspended side by side so that they were in the flow of water.  At
the end of each test period the Daphnia were counted.  

Results and Discussion

The results of this study are presented in Table 1. We did not have a
sufficient number of cages to place three at each site.  Because of the
short notice given us prior to the initial study date (April 14, 2003)
we made a new type of cage that was a failure in the field.  Thereafter,
we made additional cages of the original design we have used in the
past.  However, we ran out of the mesh used on our original cages and
substituted another type of mesh.  This mesh allowed large amounts of
sediment to enter the cages which killed the Daphnia.  Therefore, for
each test date, we only have two reliable cages (data points) – Cage 1
and 2 (See Table 1).   

On April 16, 2003, recoveries of Daphnia pulex were high in cages 1 and
2 at all sampling sites (Table 1).  As this was supposed to be a
pre-spray time period, this was to be expected.

On May 22, 2003 Daphnia recoveries were extremely low at the YC01 site
and somewhat lower at the BC01 site than the other sites (Table 1).    

On June 12, 2003 recoveries were fairly high at all sites except the
Maxfield bridge site where 100% mortality had occurred (Table 1). 

Table 1.  Daphnia pulex recovered from in situ cages

April 16 2003

				(Daphnia placed in situ on April 14)

				Number of Daphnia recovered

Cage 1  Cage 2  Cage 3*	        mean + standard error

(Mean is for cages 1

 and 2 only)

Brender Creek 1 (BC01)	8	8		7		8.0  +  0

BC02				9	8		5		8.5  + 0.5

Mission Creek 1 (MC01)	9	8		0		8.5  + 1.0

MC02				9	9		0		9.0  + 0

YC01				10	10		4		10.0  + 0

Maxfield Bridge (PC01)	10	10		4		10.0  + 0

* cages 3 was of a different design from cages 1 and 2 (original design)
and obviously did not work well.

May 22 2003

				(Daphnia placed in situ on May 19)

Number of Daphnia recovered

Cage 1	Cage 2	Cage 3*                   mean + standard error

(Mean is for cages 1

 and 2 only)

Brender Creek 1 (BC01)	7	6	2			6.5 + 0.5

BC02				9	10	2			9.5 + 0.5

Mission Creek 1 (MC01)	10	8	4			9.0 + 1.0

MC02				8	9	0			8.5 + 0.5

YC01				0	1	3			0.5 + 0.5

Maxfield Bridge (PC01)	8	7	0			7.5 + 0.5

*cage 3 was the original design (same as cage 1 and 2, but a different
type of mesh was used (we ran out of the original mesh and were unable
to obtain more of it).  The new mesh let in large amounts of sediment
and killed the Daphnia.

June 12, 2003

				(Daphnia placed in situ on June 9)

				Number of Daphnia recovered

Cage 1	Cage 2	Cage 3*                   mean + standard error

(Mean is for cages 1

 and 2 only)

Brender Creek 1 (BC01)		10	7			8.5  + 1.5

BC02					8	6			7.0 + 1.0

Mission Creek 1 (MC01)		8	9			8.5 + 0.5

MC02					9	10			9.5 + 0.5

YC01					10	10			10.0  + 0

Maxfield Bridge (PC01)		0	0			0    + 0

* we only used two cages on this date because we never resolved the mesh
issue mentioned above. 

APPENDIX B

Bank Erosion Index

This study examined Mission, Brender, and Yaksum Creeks in central
Washington to develop an estimate of bank erosion rates.  This study is
part of a larger water quality study in the region.  Pesticides and
other potentially harmful substances may be present in the soil of the
banks.  While we normally expect bank erosion to affect water quality by
adding suspended sediment, in this area, bank erosion may have even
greater water quality impacts.

Mission Creek drains an area of approximately 93 square miles, and flows
into the Wenatchee River at the town of Cashmere, Washington,
approximately 10 miles west of the city of Wenatchee.  Brender Creek and
Yaksum Creek are tributaries to Mission Creek.  Brender Creek, the
larger tributary (approx 12’ wide at bankfull), meets Mission Creek
less than 1000’ from the mouth of Mission Creek, and historically may
have been a tributary to the Wenatchee instead of Mission Creek (NRCS,
1996). According to Davis (1996), Brender Creek historically “has a
record of dryness during the late summer”.  Yaksum Creek, an
intermittent stream, meets Mission Creek approximately 2 miles from the
mouth of Mission Creek.  With a bankfull width measured at just over 4
feet, it is a significantly smaller stream than Brender Creek.  

All three creeks have been highly altered since the first European
settlers arrived.  Currently, much of the drainage basin of Brender and
Yaksum creeks, and much of the lower basin of Mission Creek, is
dedicated to either orchards or urban development.  In addition to the
typical human-caused changes in agricultural and urban areas, such as
straightening, bank protection, channelization, and increased flow peaks
due to impervious surface, Mission and Brender Creeks periodically
receive significant trans-basin flow.  Excess irrigation water carried
via canal from other basins is discharged into both Brender and Mission
Creek, often during peak flow periods.  

Likely as a result of these manipulations, all three creeks have
experienced pronounced, and in some cases, severe downcutting. 
Downcutting oversteepens the banks, and often leads to increased bank
erosion.  Since much of this bank erosion takes place on agricultural
land that has been treated with various pesticides, some of which may
linger in the soil, bank erosion plays a significant role in
understanding how pesticides might move through the environment.  

This study examined Mission, Brender and Yaksum Creek using a
methodology developed and tested by Rosgen (2001) referred to as the
BEHI or Bank Erosion Hazard Index method.  Several stream parameters are
measured in the field, and assigned an objective? “rating” and an
index value.  The values are added together to produce an erosion hazard
rating of Low, Moderate, High, or Extreme.  Each rating corresponds to a
curve on the following chart of Near Bank Stress vs. Bank Erosion Rate. 
Hence, by determining the BEHI and the near bank shear stress, the bank
erosion rate can be predicted.  

The relationships used in this methodology were determined and tested by
Rosgen, and found to produce accurate results, where tested.  However,
the empirical relationship between the BEHI and the actual erosion rates
varied somewhat depending on location and stream type.  To achieve the
most accurate predictions, the methodology should be calibrated by
region and stream type.  Unfortunately, to our knowledge this
methodology has not been tested or calibrated in this area.  Though this
study used the published empirical relationships for the region and
stream types most similar to the Mission Creek watershed, without
calibration, our results may not be as accurate as Rosgen’s, and there
is no simple method for calibrating them.  However, if at some future
date the chart can be tested and calibrated, the predictions in this
report can be revised.

The factors that determine the BEHI are 1) The ratio of the bank height
to the bankfull height, 2) the ratio of the root depth to the bank
height, 3) rooting density in the bank, 4) bank angle, 5) proportion of
bank protected, 6) bank material, and 7) structure of bank material
(i.e. layering of sediments).  Near Bank Shear Stress, as labeled on the
chart, is actually the ratio of the shear stress at the center of the
stream to the shear stress of the near-bank portion of the stream.  

Our field measurements were made on 4 June 2003, with Mission and
Brender creeks flowing near bankfull.  It is unclear how Rosgen arrived
at numbers for rooting depth and rooting density.  For our analysis, we
simplified rooting density, assigning each site to a category of low,
medium, or high, based on the density and type of vegetation on the
banks.  For example, a bank dominated by trees and woody shrubs was
rated “high”, while banks with thin grass cover were rated
“low”.  Every effort was made to be consistent in our ratings. 
Rather than similarly estimating rooting depth, we decided to eliminate
this category from our data.  In our analysis, all sites were given the
same value of “moderate” with a corresponding score of 5.

In total, 12 sites were evaluated on Brender Creek, 7 sites on Mission
Creek and 3 sites on Yaksum Creek.  The sites are located on Figures
1-3, below.  The field data and the BEHI analysis are shown at the end
of this report, but a summary of the data appears in Table 1.  The
erosion rate is the rate predicted by Rosgen’s methodology; the volume
is the rate times the height of the bank times the length of the reach.



  

Figure   SEQ Figure \* ARABIC  3  - Lower Mission & Brender Creeks

Figure   SEQ Figure \* ARABIC  4  - Upper Brender Creek

Figure   SEQ Figure \* ARABIC  5  - Upper Mission Crek and Yaksum Creek

This analysis indicates that Brender Creek, though not the largest, is
the source of approximately twice as much bank-derived sediment as the
other two creeks combined.  The field data indicates that high, steep
banks contribute significantly to the erosion prediction on Brender
Creek.  The two factors together may indicate that Brender Creek is
continuing to downcut, making the banks higher and steeper.  However,
much of the sediment entering Brender Creek from above Reach 5 (see
Figure 1) is likely to be trapped in Reach 5, which contains both a
large constructed pond and a long segment of more-or-less natural ponds
with very slow moving water even at higher flows.  These ponds likely
serve as sediment traps, preventing most of the sediment from moving
downstream to Mission Creek and the Wenatchee beyond.  

For its size, Yaksum Creek produces a great deal of bank-derived
sediment.  The factors that influenced the high predicted erosion rate
on Yaksum Creek were primarily the height of the bank, the lack of bank
protection, and the bank material.  Of these, the height of the bank
indicates a potential disturbance, indicating downcutting.  It was noted
in Reaches 2 & 3 (Figure 3) that Yaksum Creek had developed a floodplain
within a larger gully.  Often, a stream that is destabilized will
experience a period of downcutting, followed by a period of channel
widening.  Eventually, the stream reaches a new equilibrium, developing
a new floodplain within the gully created by the previous downcutting
and widening.  Hence, Yaksum Creek may have re-established a new
equilibrium in Reaches 2 & 3.  If so, Yaksum Creek likely produced even
more sediment in the past, as the channel was adjusting to its new
equilibrium.

Mission Creek also shows clear signs of downcutting, with all but Reach
6 rated as High, Very High, or Extreme hazard with respect to bank
height.  However, the vegetation on the banks of Mission Creek is dense
and well established, helping it to resist erosion.  Very few areas of
oversteepened bank exist on Mission Creek, unlike Brender Creek.  

While this methodology and the empirical relationships that correlate
the BEHI measurements to bank erosion rates have not been tested before
in this region, the data gathered still produces a useful analysis of
the streams.  Though the actual bank erosion rates may differ from those
predicted, the relative erosion rates should prove to be largely valid. 
In the future, it would be helpful if actual erosion rates could be
measured at the sites where our data was gathered.  Such measurements
would allow us to calibrate the empirical relationships and make
prediction of bank erosion more accurate in this region.

References:

Davis, D. 1996, Wenatchee River watershed ranking report addendum. 
Chelan County Conservation District, Wenatchee, WA.

NRCS, 1996, Inventory and Analysis Report for Mission, Brender, and
Yaksum Creeks.  In Davis, D. 1996, Wenatchee River watershed ranking
report addendum.  Chelan County Conservation District, Wenatchee, WA.

Rosgen, D.L., 2001, A practical method of computing streambank erosion
rate.  Proceedings of the Seventh Federal Interagency Sedimentation
Conference, Vol. 2, pp. II - 9-15, March 25-29, 2001, Reno, NV 

Data & Analysis:

APPENDIX C

 

 

 

 

 Half-life of DDT varies from as much as 58 days to 150 years.  It has
been found to be about 15 – 20 years in aerated soils.

 PAGE   

 PAGE   17 

 PAGE   

 PAGE   33 

 PAGE   41 

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Figure 3. DDT and TSS for all Yaksum Creek water samples.

 

Figure 4. DDT and TSS for all lower Brender Creek water samples.

Table 1 - Summary of BEHI analysis

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For

Water Quality Engineering, Inc.

103 Palouse St, Suite 2

Wenatchee, WA 98801

Bank Erosion on Mission Creek, Brender Creek, and Yaksum Creek using the
Bank Erosion Hazard Index (BEHI)

By

The Watershed Company

1410 Market St

Kirkland, WA 98033