# Lower Similkameen River Arsenic Total Maximum Daily Load

Submittal Report For Joint Issuance

January 2004 Publication Number 03-10-074

# Lower Similkameen River Arsenic Total Maximum Daily Load

Submittal Report For Joint Issuance

Prepared by :

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

In Consultation W ith

Lorraine Edmond Uni t e d St at es Environm ental Protection Agency

January 2004 Publication Num b er 03-10-074For additional copies of this docum ent contact:

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

Telephone: (360) 407-7472

Ad a m s

As o t i n Be n t o n C h el an C l a lla m

Cl a r k C o lum b ia

Co w l i t z D ougla s F e rry

F r an kl i n Ga r f i e l d Gr a n t Gr a y s H a r bor Is la n d

J e ffe r s o n

Ki n g K i t sa

p

K i tti ta s

K l i cki t a t Le w i s c Lin c oln

M aso n Ok a noga n

Pa c i fi Pe n d O r e ill e

P i erce S a n Ju an
S kag i t

S k am an i a S pok a n e Ste v e n s

Thu r s t o n S noho m i s h

W a h k i aku W a lla W a lla W h at co m

Wh i t m a n

Ya k i m a m 

### No r t h w e s t 425- 649- 7000

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# Table of Contents

Page
List of Tables

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

List of Figu res ................................................................................................................ ................ ii

Executive S u mmary .............................................................................................................. ....... iii

Introduction

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

Components of the TMDL

......................................................................................................... .. 2

Background

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

Applicable Criteria

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

Water Qua l ity and Resource Impa irments

................................................................................ 9
Technical Approach and Results

................................................................................................. 9
Loading Capacity

............................................................................................................... ......... 10

Load and Wasteload Allocations

............................................................................................... 10

Seasonal Variation

............................................................................................................. ......... 12
Margin of S a fety

............................................................................................................... ........... 14
Summary Implemen tation Strategy

.......................................................................................... 15
Activities that Support this TMD L

........................................................................................... 19
Monitoring Strategy............................................................................................................

........ 19
Supporting Regulations and Land Management Plans

........................................................... 19

Reasonable Assurance

........................................................................................................... ..... 19

Public Participation

........................................................................................................... ......... 20

References Cited...............................................................................................................

........... 20
Definitions and Acronyms

....................................................................................................... ... 21

Appendix A

..................................................................................................................... ........... A-1
Appendix B

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

Similkameen River TMDL Page i

# List of Tables

Page

Table 1

........................................................................................................................ .....................4

Table 2

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

Table 3

........................................................................................................................ ...................13

Table 4

........................................................................................................................ ...................17



# List of Figur es

Figure 1

....................................................................................................................... ....................5

Figure 2

....................................................................................................................... ..................13

Page ii Similkameen River TMDL

# Executive Summary

Basin: Okanogan River (W ashington)

Sub-basin: Sim ilka m een Key Impaired Resources: Water Quality

Uses Affect ed: Class “A” water, W a ter Supply (Dom estic), consumption of aquatic organism s Type of I m pairm e nt: Elevated co ncentration s of arsenic

Pollutan t : Arsenic

Contribution Factors: Historic m i ning practices and Natural sources

The Sim ilkam een River originates in the Cas cade Mountains along the international border between British Colum b ia and W a shington Stat e. The Pasayten River flows north out of W a shington to join the S i m ilkam een River in Br itish Colum b ia. The Sim ilkam een River then turns south to cross the border and m eet the Okanogan River at Orovill e, Washington. Mining, forestry, ag riculture, and recreati on are the m a jor land-use activities.

Under Section 303(d) of the fede ral Clean W a ter Act, the Sim ilk a m een River has been listed by Washington State for non-attainm e nt of the EPA hum a n health criteria for arsenic. A Total Maxim u m Daily Load evaluation wa s therefore conducted for the por tion of the river that flows through W a shington State, as required by the Clean W a ter Act. The m a jor source of arsenic appears to b e a lega cy re sulting f r om histor ica l mining ac tiv ities, m o stly in British Co lum b ia between Hedley and the U.S. border. The only si gnificant sources identified in W a shington were: 1) Palm er Lake, likely arising from periodic flooding and sedim e nt deposit by the Sim ilka m een River and perhaps inputs from Sinlahekin Cr eek, and 2) re-suspension of contam inated sedim e nts. It was determ ined that the Sim ilkam een River natu rally exceed s the EPA arsenic criteria upstream of the areas disturbed by m i ning near Hedley, BC. Under these circumstances, natural conditions constitute the wa te r quality c r iteria. Bec a us e arsen i c lev e ls na tura lly exceed criteria, the loading capacity for the river is se t equal to the natural b ackground concentration of arsenic.

Seasonal water quality targets ar e 0.4 – 0.6 μg/L total recoverabl e arsenic, and estim a tes are provided of the load reductions needed in Bri tish Colum b ia and W a shington State to m eet the targets. The targets m a ke no allowance for the do wnstream increas e in ars e nic concentrations that m i ght occur naturally as the Sim ilkam een flows through British Co lu mbia and Washington. If new data or analysis can pr ovide a reliable estim ate of wh at that increase would be, the

num e rical targets shou ld be revis e d u p ward accordingly.

Due to the n a tura l and le gacy na ture of the contam inant sources, an arsenic m onitoring plan is the suggested im ple m entation action for the Si m ilkam een River. The plan recomm ends : 1) periodic m o nitoring of arsenic in the Sim ilka m een to further define the long term changes in the

Similkameen River TMDL Page iiilegacy load of arsenic, 2 ) re newing arsenic m onitoring of the ri ver in W a shington if and when

m i ning related cleanups are undertaken, and 3) monitoring the Sim ilka m een River at Oroville during a s i g n ificant h i gh water even t to character ize arsenic and sedim e nt move m e nt in the high water conditions.

Page iv Similkameen River TMDL

# Introduction

Section 303(d) of the federal Cl ean W a ter Act m a ndates that the sta t e e s tablish Total Max i m u m Daily Loads (TMDLs) for surface w a ters that do not m eet standards after application of technology-based pollution controls. The U.S. Environm ental Protection Agency (EPA) has established regulations (40 CFR 130) and deve loped guidance (EPA, 1991) for setting TMDLs.

Under the Clean W a ter Act, every s t ate has its own water quality standards designed to protect, restore, and preserve water qualit y. Water quality standards consist of 1) designated uses, such as supporting cold water biota and providing a dr inking water supply, and 2) criteria, usually

num e ric, to achieve those uses. W h e n a lake, river or stream fails to m eet water quality standards after application of requi red technology-based controls, the C l ean W a ter Act requires the state to place the water body on a list of "impaired " water bodies and to prepare an analysis called a Total Max imum Daily Load (TMDL).

The goal of a TMDL is to ensure the im paired water will a tta in water qua lity standard s

. A TMDL inclu d es a written

, quantitativ e assessm en t of water quality problem s and of the sources that cause them . The TM DL determ ines the am ount of a given pollutant that can be discharged to the water body and still m eet standards; this is ca lled the load ing capac ity. The TMDL also allocates that load am ong the various sources.

The TMDL also m u st consider s easo n al variation s and inc l ud e a m a rgin of saf e ty that takes into account any lack of knowledge about the cause of the water quality problem or its loading capacity. Th e sum of the individu al a lloca tions an d the m a rgin of sa fety must be equal to or less than the loading capacity.

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

• Summ arize data th at docum ent the stream segm ents exceedin g state stand a rds for ars e nic.

• Summ arize the results of a techn i cal assessm ent perform e d to identify probable sources of arsenic lo ading that cause increases in ar s e nic concentratio ns and an es tim ate of the

m a gnitude of those impa cts on stream arsenic concentrations [Johnson, 2002].

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

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

A Detailed I m plem entation Plan will be develope d within a y ear of TMDL approval. Further public input will be soug ht to he lp prepare this p l an, which will identify how, when, and where voluntary restoration activities will be imple m ented. Details of a m onitoring plan will be developed. The W a shington State Departm e nt of Ecology (E cology) and other en tities will provide technical assistan ce and seek additional f unding for these activities.

This Total Maxim u m Daily Load ( T MDL) f o r arse nic in the Sim ilka m een River basin addresses the two segm ents of the Sim ilka m een River as included on the 1998 S ection 303(d) list of

Similkameen River TMDL Page 1impaired surface waters. The water b ody identification num ber for the Sim ilkam een River addressed by this TMD L is: ND93YL . Additionally, the Sim ilka m een tributary Palm er Creek, connecting Palm er Lake to the Sim i lkam een Rive r, was found to have significant loading of arsenic and is included in this TMDL. The W a ter Body ID for Palm er Creek is LE24CF

.

The Confederated Tribes of the Colville Reserv ation have asked EPA to issue this T M DL for those portions of the Sim ilka m een River that ar e within Indian allo tm ents and other Indian country, as that term is defined in 18 U.S. C. § 1151. Since the wa ter quality standards issued for the Colville Indian Reservation by the U.S. EPA on July 6, 1989 do not apply to the Indian allotm ents and other Indian country lands outside of the Colville Reservation that are covered by this TMDL, EPA has used the W a shington St ate water quality standa rds as guidance for developing those portions of this TMDL to be issued by the E P A. 

# Components of the TMDL

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

Loading capacity The loading capacity is the am ount of pollutant that a water body can rece ive without violating water quality standards. The load ing capacity is a lloca ted between waste load allocations, load allocations, natural background, a nd a m a rgin of safety. In the Sim ilka m een River basin, the water qua lity is natu rally eleva t ed in arsenic. Th e natural co ncentration of arsenic in the Sim ilkam een River in B r itish Columbia, upstream of m i ning activ ities, exceeds th e applicab le criter ia, tak i ng up the en tir e lo ad ing capacity of the river.

Wasteload allocations A wasteload allocation is a portion of a receiving water' s loading ca pacity that is allo cated to a point sour ce of pollution

. The only p e rm itted dis c harge r of waste water to the Sim ilkam een River is the city of Oroville W a ste W a ter Trea tm ent Plant (WW T P)under Nation a l Pollution Discharge E lim ination S y stem (NPDES) pe rm it num b er W A

- 002239-0. Because there is no capacity for a m easurable increas e in arsenic in the river due to the WWTP discharge, an analysis of the potential impact of the discharge was conducted. Th is analysis used “worst case” inputs to evaluate the impact the discharge from the plant could have on the Sim ilka m een water quality, and concluded that the im pa ct would not be m easurable. Based on this analysis, the Oroville WWTP wasteload allo cation was calculate d u s ing the current capacity of the WW TP and the federal Safe Drinking W a ter Act standard for arsenic in m unicipal water system s. The derived wasteload allocation was found to be an insignificant impact to the water quality at a sensitive low-flow river condition.

Load allocations The load allocation is that portion of the re ceiv i n g water' s loa d ing capac ity that is attr ibuted to nonpoint sources of pollution or to natural back ground sources. The Sim ilkam een River is over its lo ading capacity for arsenic comp ared to natural background at Princeton; therefore load allocations are zero for anthropogenic nonpoint s ources. The load allocation for natural nonpoint

Page 2 Similkameen River TMDLsources is the load that w ould yield a concentration e qual to the natural background concentration. Data needed to convert from th is concentration to a load do not exist. Margin of safety EPA requires that a TMDL include a m a rgin of safety to account for any lack of knowledge concerning the relationship between loads and w a ter quality. In this TMD L , a m a jor unknown is whether th er e would be a natura l inc r em ental in crease in arsen i c concen trations downstream of Princeton and, if so, what that rate of increase would be. The num e ric ta rgets and load reductions

recomm ended to m eet them assum e no natural increas e, thu s constitutin g an im plicit m a rgin of safety.

The W L A for the Oroville W W T P has been se t to th e drinking water standa rd for the municipal water supply. The potential contri bution of arsenic from the WWTP WLA has been exam ined and found to be insign ificant at low flow river co nditions wh en the Sim ilkam een River would be most vulnerable to additional loading.

Seasonal variation

The Sim ilkam een River’s natural background arseni c concentration fluctu ates over each annual cycle. The arsenic concentration rises with the high water flows that typically occur in May and June. In the months from Septem be r through A p r il, water flow volum es are substantially lower and the natural background concen tration of arsenic is lower than in the spring, though the arsenic concentration s t ill exceed s th e water quality criteria. The goals for this TMDL have been set to reflect the seasonal change of the natu ral background concentratio n. Higher goals are set for the spring and early summ er seasons to reflect the natural changes in background concentratio n. 

# Background

The 72-m ile long Sim ilkam een River originates in the Cascade Mountains along the international border between British Colum b ia and W a shi ngton State. It flows north out of Manning Provincial P a rk, then turns south to cross the bo rder and m eet the Okano g an River at Oroville, the last 27 m iles being in W a shington (Figure 1) . The clim a t e is sem i -arid over m u ch of the basin. Mining, forestry, agriculture, and r ecreatio n are th e m a jor land-use activ ities.

The Sim ilkam een drains 9,308 square m iles, over 90 percen t o f which is in British Co lum b ia. Peak f l ows norm a lly occur in April to July as a result of snowm e lt (Figure 2). Stream flow during the winter generally stays low due to freezing weather that m a intain s or contribu tes to the snowpack; exceptions occur when m i ld weather and heavy rain com b ine to cause flooding. The annual average discharge is 2,300 cfs; the averag e for Septem ber is 609 cf s (at Nighthawk, WA).

Mining occurs at a num ber of lo cations in British Colum b ia, a lthough a detailed accounting of the m i ning activity was not obtained for the pr esent report. Pommen (2001) summ arized the early gold mining as follows: “Placer gold m i ning took place in the 1860s and 1870s, and hard rock m i ning began in the late 1890s, with 1905- 55 being the most productive period. There have been 77 past producers in the basin.”

Similkameen River TMDL Page 3Shaw and Taylor (1994 ) m e ntion the followi ng m i nes in British Colum b ia: Sim ilco Mines
copper m i ne between the Sim ilka m een River and Wolfe Creek, below Prince ton; eleven placer

m i nes along the Sim ilkam een and Tulam een rivers , including the Dankoe silver/gold m i ne near the U.S. border; and the large Corona Nickel Plate Mine and Candorado Mines Ltd. near Hedley, which m i ne gold or process tailings for gol d. As of 1994, other m i nes were proposed near Hedley. Similco is currently in caretaking stat us. The Nickel Plate a nd Candorado m i nes have been closed and under recl am ation since about 1997.

Downstream of the border, the Sim ilkam een flow s though arid sagebrush te rrain typical of northcentral W a shington. Approxim a tely six m iles belo w the border, the river m eets Pal m er Lake outlet, som e tim es called Palm er Creek. A unique hydrologic feature of their juncture is that, during the spring, high f l ows in the Sim ilka m een can cause Palm er Creek to reverse direction and the river flows into the lake. Based on obs ervations during the technical study (Johnson 2002), this appears to occur at flows greater than 5,000 cfs. Othe r than Palm er Lake, Washington tribu t ar ies to the Sim ilkam een are dry m o st of the year, ex ce pt at higher elevations.

Table 1: Wate r Body Identificatio n Numb ers fo r water b odie s addresse d in this Similkam een R i ver Ars enic TMD L

Wa ter B o dy Nam e Ne w W a ter B o dy ID Number Old Water Bod y ID Number Included in 1996 3 03(d) List for ar se nic Included in 1998 3 03(d) List for ar se nic
Similkame en River ND93YL WA-4 9-1 030 No Yes

Palmer Cre e k LE24CF -NA- No No

Page 4 Similkameen River TMDLSimilkameen River TMDL Page 5Page 6 Similkameen River TMDL

# Applicable Criteria

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

Stream s in the Sim ilka m een watershed are desi gnated as Class A as designated under WAC 173- 201A-120(6). The characteristic uses designa ted for Class A waters and protection in Sim ilka m een River basin stream s are as follows (Chapter 173-201A W A C):

"Characteris tic us es. Characteristic us es shal l include, but not be lim ited to, the following: (i) Water supply (dom estic, industrial, agricultural). (ii) Stock watering. (iii) Fish and shellfish:
- Salm onid m i gration, rearing, spawning, and harvesting.
- Other fish m i gration, rear ing, spawning, and harvesting.
- Clam and mussel rearing, spawning, and harvesting.
- Crustaceans and other shellfis h rearing, spawning, and harvesting. (iv) W ildlif e habita t. (v) Recreation (prim a ry contact recreation, sport fishing, boating, and aesthetic enjoym ent). (vi) Comm erce and navigation."

This TMDL is designed to address impairm e nts of characteristic uses caus ed by elevated arsen i c concentratio ns.

WAC 173-201A contain s arsen i c crit eria to pro t ect aquatic lif e. Because this criteria d o es not protect all designated uses for class A waters (i.e. use of water as a dom estic supply and harvesting of organism s), the Clean Water Act require s the u s e of the water quality c r iter ia se t in National Toxics Rule, C h apter 40 of the Code of Federal Regulati on part 141.36 (40CFR131.36).

The National Toxics Rule defines the criteria fo r arsenic for the protection of hum a n health. The

num e ric arsenic criterion is 0.018 μg /l for the consumption of water and organism s. In this case, the natural background value of the S i m ilka m een River exceeds the NTR cr iterion at Princeton, BC, which is high in the watershed and upstream of the areas disturbed by gold m i ning activity.

Similkameen River TMDL Page 7WAC 173-201A-070 is applicable to the Sim ilk am een River’s condition where the natural background arsenic concentration is higher than the arsenic criterion in the NTR. Sub- part 2 states: “W henever the natural condi tions of said waters are of a lower quality than the criteria assigned, th e natur a l co nditions shall c onstitu te the water qua lity criter ia.”

The Safe Drinking W a ter Act was applied in de term ining the reasonable m a xi m u m loading from the city of Oroville m unicipal WW TP. Discharg e of arsenic from the WWTP is controlled by the concentration of arsenic in the drinking water. Th e city of Oroville has a m unicipal water source that comp lie s with the m a xim u m contam inant lev e l f o r ars e nic in dr inking water se t in 40CFR141.62.

Page 8 Similkameen River TMDL

# Water Quality and Resource Impairments

The Sim ilkam een River was included in W a shi ngton’s 1998 list of impaired waters comp iled under section 303(d) of the Clean Water Act. The 1998 listings for the Sim ilka m een river included two segm ents for arsenic (segm e nt lo cations by township-range-section: 40N 25E 13 and 40N 27E 28) and one segm ent for temp erature (40N 27E 28). This T M DL addresses only the arsenic listin gs. The Sim i lkam een River consisten t ly has higher concentrations of arsenic than other water bodies in W a shington. T h e Sim ilka m een River w a s included on the 1998 303(d) based on data collected at the Nighthawk Bridge in 1995 and 1996. 

# Technical Appr oach and Results

An approach of m a ss balancing was used in TM DL evaluation for arsenic in the S i m i lkam een River. The m a ss balancing was used to evaluate th e sources of arsenic load ing and their potential im pacts to the Sim ilka m een River w a ter quality. This study approach used several techniques for the collectio n of surface water data, s e dim e nt da ta, and disch a rge inform ation from the Oroville WWTP, the only perm itted discharger in W a sh ington. Data collected was used to provide

assessm ent of potential arsenic sources and to pr ovide for the comp arison data from the current study to other data sources. (Johnson 2002)

Routine m o nitor i ng f o r arsenic in th e Sim ilk a m een was provided for the TMDL by including arsenic in the m onthly monito ring program m a intained by Ecology’s Environm ental Assessm ent Program ’s Freshwater Monitoring Unit. The m o nthly m onitoring was conducted at stations 49B070, Sim ilka m een River at Oroville and 49B110, Si m ilkam een River at Chopaka Bridge, B. C.

Intensive sampling surveys were conducted fo r the Sim ilka m een River m a instem and for tribu t ary str eam s that enter the r i ver in W a sh ington State. Tributary stream and m a instem

samp ling occurred together during the intens ive samp ling events. Coupling these sampling studies allowed for the direct comp arison of the st ream inputs and the loads m easured in the river itse l f

. The in tensiv e sampling did rev eal th at Pa lm er Creek, the outlet from Pal m er Lake, is a significant arsenic source to the reach of river within W a shington.

Sedim e nt data used in the technical assessm ent were collected by Ecology staff and staff of the Colville Confederated T r ibes (Hurst, 2003). The sedi m e nt data revealed values of arsenic as high as 230 m g /Kg. These reported sediment values are sufficient to create water quality impairm e nt if they were to be re-sus pended into the water colum n.

The concentration of ars e nic in Palmer Creek app ears to b e as sociated with the sed i m e nts that

accum u late in the reach of the Sim ilkam een betw een river m ile 19 and river m ile 2 4. Stream channel m o rphology and grain size distribution in the Sim ilkam een /Palm e r Creek com p lex are indicative of deposition of sedim e nts in this re ach. The high flows in the Sim ilka m een associated with spring run off carry large s e dim e nt loads in to this reach ; this includes Palm er Creek when high flows from the Si milkam een River inundate the creek and backs into Palm er Lake. The

Similkameen River TMDL Page 9elevated ars e nic values in the sed i m e nts and wa ters of this reach are likely a result of the sedim e nt deposition from sour ces higher in the watershed. 

# Loadi ng Capacity

Loading capacity is the ability of a water body to receive pollutants and rem a in within applicable water quality criteria. T h e Sim ilka m een River upst ream of m i ning disturbances naturally exceeds the wate r qu ality cr ite ria set in the N T R. Due to th e natural concentrations of arsenic in the river, the loading capacity for the Sim ilkam een River is taken up by the natural background loading to the r i ver. Th e result of th e natur a l lo a d ing is th at there is no av ailab l e lo ading capacity to allocate to other significant po int or anthropogenic non-point sources of arsenic. T h e natural background arsenic concentration is used as the loading capacity and as the TMDL target con centration for this TMDL.

Derivation of the natural backgr ound concentration is described in detail in the attached TMDL Evaluation Report, (TMDL Appendix B), pp 35-39. The analysis uses data from Princeton, BC, a monitoring station upstream from the areas impacted by m i ning. Data from 1990-1999 were summarized and the resu lts were compared to s i mila r data f r o m som e of t h e least disturbed watersheds in W a shington’s am bient monito ring database. The natural background arsenic concentration, and the correspond ing loading capacity, varies seasonally from 0.4 to 0.6 ug/l (see Table 3 below). 

# Load and Wasteload Allocati o ns

The “load allocations” and “wastelo ad allo catio ns ” are the p o rtions of th e stream' s loading capacity that are designated, or “allocated,” for each source of pollution. “Wasteload Allocation” ref e rs to that portion of p o llution tha t origin ates f r o m point so urces or p e r m itted disch a rges to the water body. “Load Allocation” refers to the non-point sour ces of pollution.

No localized, non-point sources of arsenic were det ected in W a shington as a result of the present investigations. No load allocations were m a de for anthropogenic non-poin t sources. The natural load tak e s u p all of the a ssim ilative c a pacity of the rive r re sulting in th e allocation f o r n a tura l sources being set equal to the natural background concentration.

The data that would be required to convert from the natural backgr ound concentration to a natural nonpoint source load throughout the ba sin do not exist. The TMDL Evaluation report (Appendix B, p 42) does include estim a ted load re ductions required to meet water quality targets at th ree lo cations.

The single wasteload allocation ass i gned in th is TMDL is f o r the c ity of Oroville’s W a ste W a ter Treatm e nt Plant (W W T P). The city of Oroville WW TP is the only perm itted d i scha r g er to the Sim ilka m een River. The city of Oroville disc harges under the authority of their National Pollution Discharge E l im ination Syst em (NPDES) perm it number W A -002239-0.

Page 10 Similkameen River TMDLThe Oroville waste wate r tre a tm ent plant d i scha r g es waste w a ter with a c oncentr ation of arsenic that does not appear significantly different than th e arsen i c co ncentration in the m unicipal water system for the city of Oroville. Thes e concentr ations are approxim a tely 3 μg/L. Municipal water collected by the waste w a ter sy stem does not app ear to chang e in ars e nic concentratio n as it moves from the ground water source to the WWTP.

Because there is no load capacity for a m easurable increase in arsenic in the river due to the WWTP discharge, an analysis of the potential impact of the disc harge was conducted. In order to ensure protection of water qualit y, this analysis used “worst ca se” scenario inputs to evaluate how m u ch the discharge from the plant m i ght increas e the arsenic con c entration in the Sim ilka m een River. The inputs included the lowest reasonable flow in the river com b ined with the highest flow from the current plant along w ith the highest arsenic concentration that the city’s drinking water system could provide to the WWTP.

The revised standard for arseni c in drinking water under the federal Safe D r inking W a ter Act is 10 μg/L. The worst case contribution from th e Oroville WWTP was determ ined using the allowable co ncentr ation of arsenic in the m unici pal wate r system combined with the 0. 49 m illion gallons per day design capacity of the wastewat e rtre a tm ent plant. This re sulting wor s t case arsenic load would be 19 g/day.

At a loading rate of 19 g/day, Oroville WW TP w ould have an essentiall y undetectable effect on arsenic concentration in the Si m ilka m een River. T h is conclusion was derived by considering the potential effect of the loading from t h e treatm ent plant on a “7Q10” river low flow condition. A 7Q10 low fl ow is the lowest flow averaged over a seven day period that would be expected to occur once every ten y e ars. The Sim ilkam een River’s 7Q10 low flow of 186 cf s is m o st lik ely to occur during the August to March portion of the annual cycle wh ich has the m o st restrictive target arsenic concentration of 0.40 μg/L (J ohnson 2002). In a case where the river m eets the 0.40 μg/L target value and experi ences a 7Q10 low flow, an arseni c concentration of 10 μg/L in the effluent from the Orovill e WWTP operating at the d e sign capacity calculates to a downstream concentration of 0.44 μg/L after m i xing. This would be essentially an undetectable effect on ars e nic concentration in th e Sim ilkam een River.

The W L A for the Oroville p l ant is s e t to 19 g / da y, with a concentration not to exceed 10 ug/l because the worst case evaluation sh owed this po te ntial loading to have an undetectab le effect on the river.

There are several reason s to base the wasteloa d a lloca tion f o r

the ars e nic discharge from the Oroville WWTP on the arsenic stan dard in the fe deral Safe Drinking Water Act. These reasons include, bu t are not lim ited to: a c knowledging the sm all data set av ailable on the discharge from the waste w a ter treatm ent plant, recognizing a si ngle regulatory value for the m unicipal water system , and providing a stable targ et for the m uni cipal system th at does not fluctuate seasonally.

Current data on the WWTP discharge concentration of arsenic consists of only two data points. These data points m a y not be truly representati ve of the WWTP discharge. Setting a W L A based on the sm all data set could be unfairly restrictive to the city w h en expansion of the system is needed or if other ch ang e s are n eeded to the m unicipal water/waste wa ter system . Because the source of the m unicipal system is ground water, any expansion that re quired new wells could

Similkameen River TMDL Page 11result in a slightly different arsenic content. Future upgr ades to Oroville’s m unicipal water/wastewater system s should e x am ine water quality data from the municipal source water and discharge data to assure all known and reas onable treatm e n ts are incorporated into the water/wastewater system s i m prove m e nts to protect the water quality of the m unicipal drinking water and th e Sim ilkam een River.

Using the federal Safe D r inking W a ter Act standa rd as a basis for the W L A m a kes the regulation of the m unic i pal water system consistent. Change s to the system , such as replacing a municipal supply well, will need to address d r in king water s t andards and the TMDL WLA through

com p liance with a sing le standard. A caution a ry n o te on th is is that the city will need to watch for industrial practices th at have the ability to concentrate m i nerals in water, potentially raising the concentration of arsenic in water above that supplied in the city’s potable water.

Seasonal variability of arsenic in the municipal w a ter sy stem cannot be determ ined with the

curren tly av ailab l e da ta. Using the Sa f e Dri nking Water Act as a basis for the W L A provides assurance that the W L A can be attained throughout th e year. There will not be significant seasonal impacts from a W L A that does not vary seasonally. The W L A is considered to have insignificant impact at river low flow conditions with the m o st restrictive target value and its im pact on the river will be even less at higher flows.

Table 2: Wa ste Loa d Allocation

Was t e Lo ad Allocation
Dis c h a rg er NPDES Perm it Numbe r Pollutant Daily Load Allocation

Oroville WWTP WA-002239-0 Arsenic 19 grams / day

≤ 10 ug/l


# Seasonal Variation

Analytical d a ta on th e arsenic con c entrations in the Sim ilkameen River w a s exam ined from sources that included sample co llection points in W a sh ington and British Colum b ia. The arsenic concentration data used in this TMD L has been s p ecifically targeted to river disch a rg e volum es, but by comp aring data collection dates to river fl ow data, an estim ate of seasonal variation can be developed. The data review indicated that fluc tuation of the arsenic co n centr ation in the r i ver occurs seasonally at Oroville, WA, at Chopaka , BC, near the international boundary and above the Princeton where natural background values for the TMD L are established. The seasonal variation appears to be tied to the seasonal fl uctuation of the river flow, with the highest

m easured values having been m easured at river st ages that are rising and n earing the sp ring peak flows.

The Total Maxim u m Daily Load Evaluation for ar senic in the Sim ilka m een River (Appendix B) included m onthly m onitoring of arsenic at the Chopaka and Oroville bridges over the Sim ilka m een. Data from 2000 - 2001 followed the patt ern of higher concentr ations in the spring flows tapering off to a more m odes t level as th e river flow volum e s di m i nished and stabilized over the remainder of the year (figure 2). This data from m ont hly m onitoring from May 2000 to June 2001 occurred over a period when the Okanoga n valley received a record low amount of

Page 12 Similkameen River TMDLprecip ita tion

, resulting in river lows approxim a tely half of norm a l with only m odest spring peaks of flow and arsenic.

Figure 2: Total Re cove rable Arse nic Con c e n tratio ns Mea s u r e d in Monthly Monitorin g of Similkam een River from M a y 2000 to Ju ne 200 1 (Eco logy data)
The seasonal variation in the background data ta ken from the Sim ilka m een River at P r inceton is used to determ ine the seasonal targets for the TMDL. The Princeton m onthly average concentratio ns are presented in Tab l e 3. These av erages v a ry little ov er the year, yet repres ent substantial differences in loading due to the highe r river flows associated with the h i g h er spring values.

Table 3: Propo se d Targets for Total Re coverable Arse nic in the Similkamee n River

Month Targ et Con c e n tration (μ g/L )
M a y

- J u n e 0

. 6 April & July 0.5 August - M a rch 0.4

Similkameen River TMDL Page 13

# Margi n of Safety

The federal Clean W a ter Act require s that a m a rg in of safety be identified to account for uncertainty when establishing a TMDL. The m a rgin of safety can be explic it in the f o rm of an allocation, or im plicit in the use of conserva tive assump tions in the analysis. Several conservative assump tions and critical conditions used in the developm ent of the Sim ilkam een River TMDL provide an inherent m a rgin of safety as required by the statute.

In this TMD L , a m a jor unknown is whether there would be a natural increm ental increase in arsenic concentrations downstream of Princeton and, if so, what th at rate of increase would be. The num eric targets and load reductions recomme nded to m eet them conservatively assum e s no natura l inc r e a se, thus co nstitu ting an im plicit m a rgin of saf e ty.

The W L A for the Oroville WWTP has been set u s ing a conservative approach of exam ining “worst cas e” conditions for the WWTP discharge. Setting the WLA by usi ng the 10 μg/L arsen i c standard in the federal S a fe Drinking W a ter Ac t, (a valu e abo u t thr ee tim e s higher tha n the available data suggests ) provided ad dition a l m a rgin of safety to the TMD L . This stan dard was selected due to the WWTP discharge of arsenic is controlled by the m unicipal water entering the WWTP. The potential contribution of arsenic fr om the WWTP W L A, at m a xi m u m c a pacity of the plan t an d the m a xi mum concentration allo wed by drinking water standard, has been

exam ined and found to be insign ificant at ri ver lo w flow conditions that would m a ke it susceptible to additional loading.

There is substantial uncertainty in the quantification of tributar y loads within W a shington. Only four sam p le s were obtained from the m a jor source identified, Palm er Creek, and its av erage flow to the rive r was estim ated. It seem s unlikely, however, that th e load is seriously under or overestim ated given the consistent difference obs erved between the arsenic concentrations at Chopaka Bridge and Oroville

.

Other than P a lm er Lake outlet, W a shington tribut aries to th e Sim ilkam een are dry m o st of the year. No data were collected to establish trib utary loading during storm or snow m e lt events. There is nothing in the available data to sugge st that there are larg e unaccounted for arsenic inputs to the river within W a shington during runoff events.

Page 14 Similkameen River TMDL

# Summary Implementation Strategy

Implementation Overv i ew Under section 303(d) of the federal C l ean W a ter Act, the U.S. Environm e n tal Protection Agency requires states to identif y im paired water bodies. The Sim ilkam een River was included on Washington State’s 1996 and 1998 303(d) lists for arsenic. In 1999, Ecology identified the Sim ilka m een River as a candidate to conduc t a T M DL. Ecology used existing data and conducted field work between May 2000 and Fe bruary 2002 to docum ent conditions. After review from the Okanogan W a tershed Imple m en tation Committee and the Colville Confederated Tribes, Ecology published the TMDL technical report: A Total Maximu m Daily Loa d Evaluation for Arsenic in the Similkameen River (Appendix B). The techni ca l repo rt id entif ied historic m i ning practices in the upper watershed as the prim ary sour ce of elevated arsenic values in the Sim i lkam een River. The technical report also recognized the existe nce of natural and anthropogenic factors that contri bute to elevated ar senic values in the water. The Summ ary Im plem entation Stra tegy (SIS) summariz e s a s t ra te gy to m onitor the water quality to im prove our understanding of this watershe d, explore the legacy of arse nic contamination, and provide adaptive m a nagem e nt strategies for long term i m provem e nt of water quality in the watershed.

An SIS is needed to m eet the requ ire m ents of a TMDL subm itta l f o r appr oval as ou tlined in the 1997 Mem o randum of Agreem ent between EPA and Ec ology. It presents a clear, concise, and sequential c oncept of how the Sim ilkam een River and its p r im ary tr ibutary

, Palm er Creek, will ultim ately m eet th e water quality stan dards ove r tim e . This SIS comp lies with the f e d e ral

m a ndate of t h e Clean Water Act, W a shington Stat e laws to control point and non-point source pollution, and the 1997 Mem o randum of Agreem ent between EPA and Ecology.

This SIS will serve as guidance for developing a Detailed Implem entatio n Plan (DIP) during the
one year pe r i od af ter the TMDL has been approv ed. The DIP will des c rib e specif i c implem entation activitie s that n eed to be perf or m e d to achieve the TMDL targe t s. T h e DIP will also present a thorough plan for m oni toring implem en tation of this TMDL. It is anticipated that im ple m entation of this T M DL will docum ent long term reductions in the arsenic carried by the Sim ilkam een River wate rs.
This is a plan to m onitor and protect water quality. It is based in large m e asure on existing United States Federal and W a shi ngton State laws and regulati ons, county ordinances, and the voluntary actions of Canadian bas e d entities. Implem entation of this TMDL relies on the continued improvem e nt of m odern m i ning practices and continued vigilan ce of the water quality. The only NPDES per m itted point source, the Orovill e W a stewater Tre a tm ent Plant, contributes a negligible amount of arsenic to the loading in the river and does not result in a m e asurable increase of arsenic in the river.

The resto r ation tim ef rame f o r this T M DL is very uncertain. A downwar d (imp roving water quality) tren d in arsen i c concen trations has been noted in da ta collected f r om the Chopaka Bridge water quality sampling station 49B110 (Sim ilka m een R. @ Chopaka Br., B. C.). The downward slope in this data from 1984 to 2000 is different from spring to fall, and the inability to determ ine the source of this improvem e nt we akens any estim a tes of the resto r a tion tim ef ram e

.

Similkameen River TMDL Page 15Exam ining the trend in the Septem ber data from the period of 1984 to 1999, the trend suggests that the Sim ilkam een River at Chopaka w ould achieve the target around the year 2015. Exclusion of the earlier data and considering the trend in the data from 1990 to present m a kes the im proving trend less evident. Many f actors, such as natural shifting of th e river chan nel or severe flooding, can potentially alter or reverse the im provem e nt by re-sus pending sedim e nts that have been deposited in the riv e r cours e or floodplai n. Additionally , the Sim ilkam een River has been shown to receive significant arsenic loading below the Chopa ka Bridge station, probably associated w ith sedim e nt deposits from up-river sources. Additional tim e a nd data are needed to address this loading. At this tim e, an optim istic view would be to see the T M DL goal reached at the Chopaka Bridge station within tw o decades , and at the Oroville water quality sampling station th ree decades after that. A more realistic view of the situation is to recognize that there have been more than a hundred years of m i ni ng history in the draina ge and that the m i ning related enrichm e nt of arsenic in the water and s e dim e nts will take m a ny more years to be

m itigated.

Implementation Activ i ties This TMDL is addressing water quality impairme nt from legacy loading and natural conditions. The technic a l repo rt ide n tif ies m onitoring ac tiv ities f o r the implem e ntation of the TMDL. A downward trend of arsenic concen tra tions in the Sim ilkam een was identif ied in the te chnica l report. The downward trend in arseni c concentrations m a y be due, in part or in whole, to changes in analy tic al techniqu es over the tim e m on itoring has occurr e d. Addition a l m onitorin g will indicate if this downward trend continues and identify long term changes to this river system

. Implementation Activ i ties to Monitor Non-Point Sources:

The TMDL technical s t u dy revealed that a r each of the Sim ilkam een River that receives a substantial portion of the arsenic loading is a short reach of river characterized by features indicative of sedim e nt deposition. Th is reach inclu d es braid e d river b e ds and a unique interaction with Palm er Lake and th e connecting stream , Palm er creek. This unique interaction is characterized by reversal of the flow of wate r in Palm er creek and significant rises in the Sim ilkam een River flow. The revers al of flow reaches in to P a lm er Lake allowing s e d i m e nts from the Sim ilka m een River to be deposited in the lake and floodplain surrounding Palm er creek and the Sim ilkam een River. The deposits of se dim e nt in this area during high flows in the Sim ilka m een appear to be a sour ce of the arsenic in the river through the rem a inder of the year. Non-point sources of arsenic were no t characterized sufficiently to sep a rate natural sou r ces from anthropogen i c influenced sources. Monitoring for ch anges in the non -p oint lo ading will likely b e done at the bridge crossing at Or oville. Additional m onitoring is needed in order to determ ine whether re-suspension of bank sedim e nts in Palm er Lake and Palm er Creek is increasing instream arsen i c concen trations.

Point Sources

The Sim ilkam een River TMDL technical report identif ied the Oroville W a stewater Tr eatm e nt Plant (W W T P) as the o n ly NPDES perm itted po int sour ce in the wate rsh e d. Analysis of the effluent from the Oroville WWTP re vealed a co ncentration of arsenic of 2.85 m i crogram s per liter. The so urce of the arsenic in th e WWTP discharge app e ars to be the dom e stic wa ter supp ly in Oroville.

Page 16 Similkameen River TMDLThe Oroville water supp ly com p lies with the f e d e ral Safe Drinking W a ter Act with an arsenic concentratio n of approxim a tely 3 m i crogram s pe r liter, we ll below the 1 0 m i crogra m s per liter allowed by the federal S a fe Drinking W a ter Act. This appears to be unchanged in concentration as the water passes through the system and into the WW TP. Mon itoring the arsenic discharge of the Oroville WW TP will be incorpo r a t ed in to the NPDES perm it during the perm it cycle th at follows the issuance of this TMDL.

Table 4: This table p r e s ent s gen eral action s and entit ies re sp o n sibl e for imp l ementing su ch a c tion s. The informatio n listed in the ta ble is pa rt of the overall strategy and ma y chang e as person nel an d moneta r y resource s are be tter defined d u ring the d e velopme n t of the DIP.

Entit y Responsibilities to be met 1 2 3 4 5 6 7 8 9 10 Be y ond 10 Years
Ecology Periodi c Moni toring of the Similkame en River, Monthl y monitori ng for a year rep e a t ed on every 5 th year X X X

Ecology, local Monitor d u rin g high water events that woul d be exp e cted to reoccur o n a 10 year interval (flow of 27,03 0 CFS or greate r). X X X X X X X X X X X

City of Oroville Monitori ng arseni c in wast ewate r treatment pla n t discharge i n accordan ce with NPDES permit requi rem ents X X X X X X X X X X X

Ecology/ Local Dre dge Sam p ling Proj ect. Field data colle ction for effect of recre a tional dred ge s on a r se nic lo ad in the Similk a m ee n X

Responsible Entities an d Actions Monitoring : The Departm e nt of Ecology is th e entity currently conductin g m onthly water qu ality monitoring at the am bient water qu ality s t a tion o n the Sim ilkam een River (49A190 Okanogan River @ Oroville). Periodic m onitoring would be preform e d as part of th is water qua lity monitoring f unction.

Ecology is seeking a local partner to perform high water (flood) events. Ecology would retain the responsib ility for analysis of the samples, but a lo cal en tity (i. e .: Conser vation District, Irrigation District or city) would be m u ch better situated to provide the labor to samp le river flows on a short notice.

Ecology is planning to conduct a field investiga tion of the potential im pacts of recreational dredging on the ars e nic loading in th e water co lu mn. Ecology will be s eek ing a local d r edge operato r to v o luntarily p a rticipate in this proposed study. Ecology will be investig ating the protectiven ess of the app licab le re gulations for recreational dredges.

Similkameen River TMDL Page 17Ecology is the responsible entity for determ ining com p liance of interim and final targets.

Adaptive Management

These im plem entation activities are centered on the ga thering of long term data for the evaluation of water quality. These monitoring activiti es will s e rve to b e tte r def i ne the rate that the water quality in the basin is improving. Re-e valuation of the long-term trends with the additional data will allow the re storation tim efr a m e to be determ ined with greater precision. If the water quality m onitori ng activities show unexpect ed long term rises in arsenic values in the Sim ilka m een River, an exam ination of any pot ential new sources of arsenic should also be undertak en. Additionally , intens ive s u rveys and wa tershed in vestig ation s hould be sou ght to identif y sign if icant ev ents in the wa te rshed that could re-suspend sedim e nts.

Persis tent elevated values of ar senic or data that does not show the expected gradual d eclin e of arsenic over tim e will trigger a dditio nal investig ation under adaptive m a nagem e nt. This should include the investigation of arsenic cycling in Palm er Lake as it relates to the flood-deposited sedim e nts from the Sim i lkam een River. The inve stigation of these flood deposits should also consider the interaction o n ground water with the surface waters in th e sam e reach of th e river that received the greatest am ount of sedim e nt deposits. Further action m a y also include the coordination with upstream B.C. land m a nagem e nt agencies to discuss up stream m easures that would decrease flooding in the Palm er Lake /S im ilka m een River basin.

Potential Funding Sources Funding sources will be more fully explored in the developm ent of the DIP. At this tim e, funding for the perio d ic (repeatin g every five years) m onitoring of the Sim ilka m een River at the Oroville Station is expected be accomp lished with little funding, provide d that arsenic samp ling can be incorpor ated into th e rou tine m onthly water m onitoring that takes plac e at that location

. Incorpor atin g the ars e nic m onitoring into th e rout ine m onitoring will r e quire little add i tional tim e and labor of the samp ler and no additional m obili zation cost. Analysis for arsenic in the river water is a re latively inex pensive an alysis.

Sa m p ling of a high water event would ideally be conducted through a local entity. This would facilitate sampling a hig h water even t at sho r t no tice. Gran t funding will b e sought to f und this portion of the m onitoring plan.

Detailed I m plementa tio n Plan

A Detailed I m plem entation Plan will be prepa r ed within a ye a r f

o llowing approval of this docum ent. Further public input will be sought to help prepare this plan. The plan will identify how, when, and where monitoring ac tiv ities will be im plemented. Ec ology and other entities will provide technical assistance and seek additional f unding for these m onitoring activities and any restoration activities that m a y be identified as the body of data grows. It is the goal of this TMDL
to m eet the water quality arsenic standards by 2020.

Page 18 Similkameen River TMDL

# Activities that Support this TMDL Monitoring Strategy

The implementation stra tegy f o r the Sim ilkam een ar senic T M DL is designed to address a legacy loading of ar senic in the watershed b y histor ic m i ning prac tic es and the p e rm itted dis c harge in the watershed. Imple m entation activities include 1) m onitoring of the river m a inste m periodically at the Orov ille station, 2) m onitoring potential impact of high river flows through focused m o nitoring when a ten-year high flow (flow of 27,030 CFS or greater) occurs, 3) monitoring the discha rge of the NPDES perm itted W W T P at Oroville is a requir e m e nt of the
perm it itse l f

. 

# Supporting Regul a tions and Land Management Plans

Routine im plem entation of W a shington’s State E nvironm ental Policy Act, the Okanogan County Com p rehensive Plan and the Okanogan County Shor eline Master Prog ram will assure the review of projects proposed in the vicinity of the Sim ilkam een River for potential environm e n tal impacts. This review process should ensure best m a nage m e nt practices are used for new projects and that p e r m itted activ ities will no t im pact the implem e ntation of this TMDL.


# Reasonable Assurance

During the developm ent of the Sim ilkam een River arsenic T M DL, available data for water quality throughout the watershed w a s collected a nd evaluated. The m a ss bala nce approach to the TMDL and the quantity of data has left questio ns regarding the am ount of the natural arsenic contribution is in the watershed. The conservativ e assump tions used in the technical evaluation (Johnson 2002) burdens the anthr opogenic sources with the pote ntial natural loading below Princeton. Addition a l data on natural contribution could only raise the TM DL target h i gher than they have currently been set.

The single NPDES perm itted sourc e to dis c harg e to the rive r , the Oroville W W TP, has been found to be an insignificant cont ributor to the arsenic loading. The conditions used to determ ine the potential impact of the WW TP have been inco rporated in the current N P DES per m i t

. Monitoring the discharge water will be a c ondition of the NPDES per m it and m onitoring the source of th e m unicipal water is currently be ing accom p lished under the drinking water system regulations adm i nistered by the W a sh ington State Departm e nt of Health.

Each of thes e conserv a tive m easures will assu re that the S i m ilkam een W a tershed will be monitored and protected from activ ities th at would threa t en th e water qua lity while the legacy loading is mitig ated thro ugh tim e and nature.

Similkameen River TMDL Page 19

# Public Participation

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

# Refer e nces Cited

Hurst, Donald. 2003. Analysis of Sedim e nt from t h e Sim ilka m een River and Palm er Creek, US. Unpublished report for the Colville Confederated Tribe, Departm e nt of Environm ental Trust.

Johnson, Art, Nove m b er 2002. A Total Maximum Daily Load Evaluation for Arsenic in the Similkameen River , W a shington State Departm e nt of Ecology, Olym pia, Washington. http:// www .ecy.wa.gov/biblio/0203044.htm l (This report has been included as Appendix B to this r e por t)

Pomm en, L. 2001. E-m a il to Art Joh n son, December 4. B.C. Ministry of W a ter, Lan d and Air Protection.

Shaw, R. and B.R. Taylor. 1994. Assessm ent of Fe deral –Provincial W a ter Quality Data for the Flathead an d Sim ilkam een Rivers. P r ep. f o r Coordina ting Co mmittee of the Canada- B ritish Colum b ia W a ter Quality Monito rin g Agreem en t. Environm ental Managem e nt Associates.

Page 20 Similkameen River TMDL

# Defini tions and Acronyms

CFR Code of Federal Regu lations, usuall y preceded by chapter nu mber and followed by a section num b er (i.e. 40CFR131.36)

cfs cubic feet per second

DIP Detailed Implem entatio n Plan

EPA Unites States Environm ental Protection Agency

g/day gram s per day

NPDES National Po llutan t Disch a rge Elim ination Syste m

NTR National Toxics Rule (40CFR131.36)

RCW Revised Code of W a shington

SIS Su mm ary Implem entation Plan

TMDL Total Max imum Daily Load

WAC Washington Adm i nistrative Code

WWTP Waste W a ter Treatm ent Plant

μg/L m i crogram s per liter

7Q10 The lowest flow averaged over a seven- day period that would be expected to occur once every ten y e ars.

Similkameen River TMDL Page 21Page 22 Similkameen River TMDL

# Appendix A

Summar y of Public Involvement

Similkameen River TMDL PageA-1PageA-2 Similkameen River TMDL

## Summary of Public Involvement

Septem ber 12, 2000 Met with the Okanogan Health District Board to present introductory inform ation on the Okanogan DDT/PCB and Si milkam een arsenic TMDLs.

Nove m b er 7, 2000 Presentation on the Okanogan and Sim ilka m een TMDLs m a de to the environm ental science class at W e natchee Community Colleg e class at the Om ak br anch campus.

Septem ber 7, 2000 Presentation to the Okanoga n Conservation District Supervisor’s

m eeting to introduce the Sim ilka m een arsenic and Okanogan DDT/PCB TMDLs

February 22, 2001 Public m eeting at Oka nogan PUD to kick -off Okanogan DDT/PCB and Sim ilkam een Arsenic T M DLs.

June 12, 2001 Presentation regarding the Okanogan at the conference “Aquatic Ecosystem Health and Fisheries in the Okanogan-Sim ilkameen Basin” in Kelona, B C

July 26, 2001 Presentation on the Okanogan DDT/PCB and Si m ilka m een arsenic TMDLs to the Okanogan W a tershed Im plem entation comm ittee.

August 9, 2001 Presentation to the Oroville -Tonasket irrigation District on the Okanogan DDT/PCB and Sim ilka m e e n arsenic T M DLs.

March 5, 2002 Meeting with the Oroville City Council to discuss arsenic data needed from the Oroville wastewater treatment plan t.

April 16, 2002 Meeting to discuss arsenic data results from the samp ling the discharge of

the Oroville was t ewater Trea tm ent plan t.

Septem ber 10, 2002 Presentation to the Okanoga n County Comm issioners and invitation to participate in the Lower Sim ilka m een watershed tour.

Septem ber 19, 2002 Lower Sim ilkam een W a t e rshe d tour including representatives from Environm ent Canada, BC Ministry of W a ter air and Land Protection, BC Ministry or Energy & Mines, O k anogan Nations Alliance, Colville Confederated Tribes, US Bureau of Land Managem e nt, Okanogan County Commissioners, Okanogan Pub lic Utility District, O k anogan Health District, City of Oroville, and the citizens of Okanogan County.

October 25, 2002 Meeting with the Okanogan W a tersh e d Im ple m e n tation Comm ittee to discuss the Sim ilka m een River arse nic TMDL and the Okanogan River DDT/PC B T M DL

Similkameen River TMDL PageA-3February 24, 2003 Meeting with the Okanoga n W a tersh e d Imple m e n tation Comm ittee to discuss the Sim ilka m een River arse nic TMDL and the Okanogan River DDT/PC B T M DL

July 24, 200 3 Meeting with the Okanogan W a tersh e d Imple m e n tation Comm ittee to discuss the Sim ilka m een River arse nic TMDL and the Okanogan River DDT/PC B T M DL

Septem ber 10 to October 10, 2003 Public Comm ent Period for the Sim ilkam een Arsenic TMDL Subm ittal report. Advertis ed for public comm en t period an d m e eting placed in the Okanogan Chom ical and the Okanogan Valley G azette Tribu n e.

October 1, 2003 Public m eeting held in the evening at the Oroville City Hall. Meeting provided a f o rum to discuss the TM DL Subm ittal Report 

## Responses to Comments on the Similkameen Arsenic TMDL Submittal Report

Comm ents received fro mDavid Kliegm an, Exe c utive Director of the Okanogan Highlands Allianc e, M o McBroom , Staf f Attorney f o r W a shPIRG, and Jessica McNam a ra raised concerns that were sim ilar, if not the sam e as, concerns raised in one other set of comments. Due to these sim ilarities, these comments wi ll be addressed together.

The following comments were received concerning abandoned m i nes in the W a shington’s Sim ilkam een Drainage :

1. The draft plan for m o nitoring of arsenic TMD L s on the lo wer Sim ilkam een raises concern because the plan lacks any provision s for i nvestigating o r ad dressing po s s ible arsen i c contam ination from the m a ny abandoned m i ne s located in the Sim ilkam een watershed.

According to the Departm e nt of Natural Resour ces' Mas/Mils database, there are 71 abandoned

m i nes on the U.S. side of the border in the Sim ilkam een watershed. The major ity of th ese m i nes have never been inventoried or otherwise assessed for their environm ental impacts.

Departm e nt of Ecology' s TMDL evaluation comp leted in 2002 acknowledg es the existence of only 11 of the Sim ilka m een watershed' s 71 m i ne s. The 60 m i nes not m e ntioned in the report contain tens of thousands of m ile s of stopes, drifts, shafts and adits, as well as unknown acres of tailings and waste rock piles, any of which coul d be sources of arsenic to the Sim ilkam een River and Palm er Creek.

W ith respect to the 11 m i nes that were consid ered in the TMD L evaluation , it appears that Ecology looked only for obvious evidence of off-site drainage, and did not te st for arsenic levels, nor conduct other tests such as trace elem ent doping to verify whether arsenic or o t her m e tals from these m i nes m a y be m i grating within the watershed. Nor has Ecology taken m e asures to determ ine whether any of the 71 m i nes are contri buting particulate arsenic to the Sim i lkam een

PageA-4 Similkameen River TMDLRiver or Palm er Creek through erosion and sedi m e nt generation during spring freshets. Ecology' s conclusion in the TMDL draft repo rt that arsen i c loading in th e watershed occurs from sources "m ostly in British Columbia" is weak ened by th e comp lete lac k of inf o rm ation abou t th ese Washington m i ne sites.

W ithout adequate data on these potential sour ces of contam ination to the watershed, we are concerned that Ecology cannot pr operly imple m ent a plan to m onitor non-point sources and ensure adequate implementation of the TMDL.

Federal law requires W a shington State to identify sources of pollution in w a ters tha t f a il to m eet state water quality standards, and to develop water cleanup plans to a ddress those pollutants. Despite this m a ndate, the TMDL process f o r the S i m ilkam een River curren tly lacks sub s tantive inform ation that could be used to confirm whether or not the 71 abandoned m i nes in the Sim ilkam een watershed are sources of arsenic to the river.

For this reason, we request that you revise the T M DL to include an assessm e nt of the potential for arsenic contribu tion into the Sim ilkam een River from each of these 71 m i ne sites. We understand that the Departm e nt of Na tural Res ource (DNR) has a program for the inventory of the state' s abandoned m i nes and we respectfully suggest that Ecology m i ght work with DNR to procure the necessary infor m ation on th e m i nes in the Sim i lkam een wat e rshed.

Response: Ecology’s approach to the investigati on of Arsenic in the Similkam een River in this T M DL has been to first exam ine the arsenic concentrations in th e S i m ilkam een River reach by reach, and then id en tify potential arsenic sources associated with elev ated reach con c e n tra tions. B y starting th e inves tiga t ion at the kn own points of water qua lity im pair m e nt and working into m o re detailed divisions of the river to determ ine where significant loading to the river occurs, Ecology is identifying those sources that have the most significant impact on water quality. Ec ology’s TMDL investigation did show a significant contribution to the Sim ilkam een’s ars e nic lo ad from Pal m er creek and the Reach of River from river m ile 19.2 to 23.8. This reach is do m i nated by the accum u lation of sedim e nts deposited by high flows in the Sim i lkam een River. These sedim e nt deposits, whose source is higher in the Sim ilkam een W a te rshed, appear to be the source of arsenic producing elevations of dissolved arse nic in the river m o st of the year.

The Sim ilkam een Arsenic TMDL exam ined potential surface water connections and influence of the larger m i nes in W a shingt on’s S i m ilka m een River drainage. The TMDL investigation did not find direct links between the hard rock m e tals m i nes in W a shington and the arsenic loading in the Sim ilkam een River. The November 1990 Washington State Departm e nt of Natural Resources report “Metal Mines of Washington- Prelim inary Report” shows that each of the largest m i ne s in the region have less than a m ile of underground workings. Sixty m i nes could not pos sibly account for “tens of thousands of

m iles of stopes, drifts, shafts and adits, as well as unknown acres of tailings and waste rock piles”.

Ecology is participating with W a shington De partm e nt of Natural Resources in the

assessm ent of abandoned m i nes in Washington. Much of the assessm ent project is a joint

Similkameen River TMDL PageA-5effort between Ecology Staff a nd DNR staff. Ec ology has published the first part of the

assessm ent projec t’s f i n d ings as th e report titled : Screening Level Inves t igation of Water and Sediment Quality of Creeks in Ten Eastern Washington Mining Districts, w i th Emphasis on Metals. This publication is number 00-03-004 and is available from Ecology’s publication o ffice or it can be viewed on line at http:// www .ecy.wa.gov/pubs/0003004.pdf

.

2. The proposed schedule for periodic m onitori ng only every five years, and m onitoring only during ten-year high water events, is inadequa te to provide the inform ation necessary for

com p liance with the Cle a n W a ter Ac t. Even t hough the DOE m a y not anticipate new sources of arsenic, there are several reasons why an annua l, or at least sem i -a nnual, monitoring should continue, at leas t for a few m o re years.

Response: Ecology doesn’t expect changes to be com e evident in the space of a single year, and we believe that our current data base gives us adequate in sight into variability on shorter tim e scales.

3. The data from m onthly m onitoring from May 2000 to June 2001 occurred over a period of low precipitation and spring run-o ff. This does not reflect the years when above normal flows and flood events occurred, so a true picture does not em erge. In addition, the report asserts, "the downward trend in arsenic concentrations m a y be due in part or in whole to changes in analytical techniqu es o v er the tim e monitori ng has occurred ". It s eem s then that the results obtained, i.e., im proved lower levels of arsenic, are open to question. W a iting another five years to establish

new m easurem ents to corroborate w h ether this impr ovem e nt has really occurred is questionable.

Response: The arsen i c contam ination in the Sim ilkam een River is f r o m natural so urces

com b ined with the legacy of a hundred year s of m i ning history in the region. The long
term m onitoring prog ra m is appropr iate f o r th is situa tion an d will ac cou n t f o r variations in weather over tim e

.

4. There is no consideration give n to the fact th at m i ning IS currently occurring in portions of the Sim ilkam een both above and below Enloe Da m

. Though this is cons idered "recreational

m i ning" (i.e., gold dredging), there has been very l ittle research done as to the extent and effects. Currently the DNR has perm it applications for 25 dredges in the river, som e of these possibly commercial, which they neither m a y nor m a y not have yet approved. In addition, the D r edge Earth First rally is now planne d as an annual event which coul d bring several thousand people into th e area every August, m a ny of whom will be dredging b o th during and possibly after the rally. W ithout a continuing m onitoring program th ere will be no way of knowing what effects this am ount of dredging will have on TMDLs and what precautions m a y need to occu r.

Response: To address concerns relating to the af fect of recreational dredge m i ning on the ars e nic v a lues of the Sim ilkam een River, a field investigation of the effects of dredge

m i ning on arsenic loading in the Sim ilkam een River has now been added to the im plem entation str a tegy. The planne d investigation will be u ndertak en to determ ine the applicability of the dredge sim u lation st udy conducted by Ecology in 1999 to the arsenic

PageA-6 Similkameen River TMDLTMDL. Ecology will u s e an in-river study to be tter determ ine the water quality im pacts of recreational dredging conducted according to the rules and regulations f o r m i neral prospecting and placer m i ning in Washington S t ate as adm i nistered by th e W a shingto n State Departm e nt of Fish and Ga m e . This study should provide inform ation that can be applied to the individuals or organized groups operating within the Sim ilkam een River.

Those concerned about the regulation of recr eational dredging should be aware of the
upcom ing revision of the W D FW’s rules and regulations for m i neral prospecting and placer m i ning in W a shington Sate. O pportunitie s for public involvem e nt could begin as early as the spring of 2004.

In response to comments received by Ecol ogy, an inquiry was m a de to W a shington Departm e nt of Natural Resources (DNR) on the status of pending dre dge applic ation s in the Sim ilkam een River. The response fr om DNR was that the six outstanding application s for dredge m i ning have recen tly been denied and there are no outstand i ng applic ation s at th is tim e . (Persona l co mm unication with Mike Rechner, DNR aquatic lands, December 2003).

5. The high arsenic levels at Palm er Lake/Creek m a y be strictly a result of the washing out of the sed i m e nts from Pal m er Creek into the Sim ilkam een during the high spring flows, but m o re consideration and study need to be done on the role of Sinlah ekin Creek in adding several hundred thousand tons of sedim e nt to Palm er La ke annually. This sedi m e nt, both that which

rem a ins in the lake and that which flows into the Sim ilka m een, m a y also be contributing to arsenic to tals. As yet, th ere are no conclusions as to the am ount of sediment, where and why it is occurring, o rthe im proved m a nage ment practi ces necessary to m odera te it. Several large landslides, caused by poor logging and roading practices, have occurred in the past 20 years. If Sinlahek in Creek is a factor in increased ars e nic levels in Palm er Lake and the Sim ilkam een, then there is a need to analyze and correct this, since it is within the U.S. boundaries.

Response: Sedim e nt transport by Sinlahekin Creek has not been specifically addressed in the inf o rm ation inclu d ed in the S i m ilk am een arsenic ass e ssm ent report. The Okan ogan Conservation District has m onitored Sinl ahekin Creek as part of the Okanogan Watershed Water Quality Managem e nt Plan an d m easured th e tota l suspe nded solids in the cr eek between 1 and 10 m illig ra m s per liter and f l ows f r om 12 to 83 cubic f eet pe r second. The highest values of suspended so lids did occur during the highest m easured flow, but even if this high flow were m a in tained year around the sedim e nt transport into Palm er Lake would not approach hundreds of thousands of tons. Please consider providing the inform ation you have regarding se dim e nt transport by Sinlahekin Creek so that Ecology can evaluate it during devel opm ent of the detailed imple m e n tation plan.

Similkameen River TMDL PageA-7Comm ents Received from the Colville Confederated T r ibes :

CCT 1. As acknowledged by the aut hor, historical data used to support the conclusion that Sim ilka m een River water quality is improving is incomp arable, contradicted seasonally, and m a y in f act dem o nstra t e a de c line in water quality ove r tim e. Yet the specious tr end is used to justif y DOE’s strategy to rely solely on water m onitoring as a m e thod to achieve comp liance with water quality standards.

Response: The m onitoring strategy presented in the Summ ar y Imple m entation Strategy is intended to exam ine the long term trend in the arsenic loadi ng of the Sim ilka m een River. Ecology acknowledged that the data se t developed for this TMDL is lim ited by the clim atic conditions occurring du ring the study year. Long term m onitoring is needed to truly determine the condition of the river with differing clim a tic conditions. Additionally, the long term m onitoring plans will incor porate the review of any additional data available fro m non-Ecology sources prior to th e monitoring cycle. This will in clude any additional data available from Canadian sour ces as indicated in the action s recomm ended at the conclusion of the T M DL technical repor t. S hould the long - term monitoring set out in the subm itta l repo rt sh ow a rising trend in the a r senic conce n tra tions, th en additiona l investigatio ns and actio ns includ ed in the ad ap tive m a nagement sec tion o f the repor t will be undertaken.

CCT 2. The long term monitoring plan is pare d down significantly from recomm endations contained in the TMDL Evaluation for Arseni c in the Similkameen River . No new data was reported in the SIS that warra nts a less rigorous samp ling pl an. Logic for the dim i nished monitoring plan appears to be a c oncession to the legacy of mining and is inconsis ten t with goals and objectives of the Cle a n W a ter Ac t.

Response: Most of the recomm ended actions in th e technical report will be incorporated into th e long term m onitoring pl an included in the SIS. Period ic review of Canadian data will be incor porated into the f i ve-ye a r sa m p ling cycle in cluded in the SIS. C o ring of sedim e nts was considered by the Okanoga n W a t e r Quality Managem e nt Plan’s Imple m entation Comm ittee, but wa s not included in the SIS as is was not expected to change the options or actions available to address arsenic in the Sim ilka m een River.

The analysis of fish tissue, as suggested in the technical report, was not seen as an action that would contribute to the reduction of arsenic in the Sim i lkam een river system , but should be conducted outside the construct of the T M DL process. The W a shington State Departm e nt of Ecology partners with the W a shington State Departm e nt of Health to address health concerns relati ng to fish consumpt ion. A samp ling of fish tissue for arsenic was included in the Ecology study titled “ Investigation of B a ckground Inorganic and Organic Arsenic in Fou r Washington Lakes.” Conner’s Lake in the S i m ilka m eenSinlahekin watershed w a s included in this study. The results of th is study support the need for a fish tissu e stu dy in Palm er Lake. Ecolo gy will cons ider condu cting a fish tis s ue study for Palm er Lake and the priority of the project relative to other water quality projects proposals.

PageA-8 Similkameen River TMDLCCT 3. True, active point sources upon which to fo cus remedial m easures are problem atical on the Sim ilkam een River in the US. Instead, m o st of the ongoing releases of arsenic appear to derive through recycling of contam inated se dim e nts by re-suspension of fine- grained bank

m a terials. T h e sedim e nt source is near surf ace an d as wide as the floodplain. The SIS must summarize in the SIS for m o re carefu l developm ent in th e DI P those prac tica lly av ailable

rem e dial m e asures capable of increasing ba nk stability and decreas ing flood-driven resuspension of sedim e nts. These include Best Ma nagem e nt Practices for livestock grazing. The potential for sedim e nt stabilization through bank revegetation program s should be included in the SIS. Institutional controls should also be explored.

Response: Ongoing release of arsenic takes tw o for m s in the Sim ilka m een River. Release through re-suspension of sedim e nt occu rs during the high water/high flow events and release of dissolved arseni c occurs as a result of the long termcontact of arsenicenrich ed m a terial with th e waters in the Sim ilkameen riv e r sys t em

. Re-suspension of the sedim e nts from the Sim ilkam een River is a function of river dynam i cs in this area. Th e Sim ilka m een River in the reach b e tween the in ternational border and the entrance to the Sim ilkam een River Canyon, at river m ile 19.5, is characterized by m u ltiple channels and a wide an d activ e floodplain. The sedim e nts it transpo r ts are from both the current s t ream bed and the adjacent banks, w h ere the banks are unstable. Stream bank erosion in this ty pe of system is typified by infrequent avulsions of the stream channels as increas ing sedim e nt deposits force channel changes. When channel avulsion occurs, the new channel transports sed i m e nt from an area that

m a y have higher or lower arsenic concen tr ation th an the pr evious channel.

Dissolved a r senic is the r e sult of the contac t betw een river water and river sedim e nts that are elevated in arsen i c. T h ese releas es of disso lve d arsenic, pr im arily in th e vicin ity of the Palm er Creek confluence, create th e rise in ars e nic loading to the river that is seen between the international boundary and the city o f Oroville. T h e dissolv ed arsenic loading is the prim ary concern during m o st of the year, while arsenic-en riched sedim e nt transport is dom i nant during th e relatively short high water po rtion of the annual cycle.

Reducing or elim inating the sources of arseni c-rich sedim e nts that are de posited in th is river reach would address both loading concerns for suspe nded sedim e nts and dissolved arsenic. However, significant localized source s of arsenic-rich m a terials contributing to the sed i m e nts in the Sim ilkam een River were no t identif ied in the segm ent of river addressed by this TMD L . Further m onitoring would be required in order to determ ine whether re-suspension of bank sedim e nts in Pa lmer Lake and Palm er Creek is increasing in-stream arsenic con c entrations.

CCT 4. ...r ecreational dredging shoul d be discouraged because it aggressively re-entrains arsenic contam inated bed sedim e nt. The potential adverse effect of re creational dredging in arsenic contam inated sedim e nts is further reason to discourage the practice on the Sim ilka m een.

Response: Addressed with the dredge m i ning comments above by W A SHPIRG, Okanogan Highlands Alli ance and J. McNam a ra.

Similkameen River TMDL PageA-9CCT 5. Available m easures to help m i ni m i ze fl ooding in the United States should be summarized in the SIS. The Sim ilkam een River va lley is highly channelized in the Canadian (upstream ) reach of the river. DOE should coor d i nate with up stream B.C. land m a nagem e nt agencies to reduce flooding in the Palm er La ke/Sim ilka m een River basin by rem oving upstream levees and riprap where feasible and avoiding further construction of channeling structures.

Response: The scope o f this TMDL is lim ited to that po rtion of the Sim ilkam een River that flows through W a shington State. Howe ver, the Sim ilka m een River that flows through W a shington is greatly influenced by the conditions in Canada. The Okanogan Conservation District and the National Resour ces Conservation Serv ice have considered and rejected stream bank stabilization in the W a shington Reach of the Similkam een because it w ould need to be on the sam e scale as the Canadian river chann e l controls to have a chan ce of resis tin g the river f o rces as sociated with th e rel ease of water from the diked river channel in Canada. It also needs to be acknowledged that this scale of stream stabilization would elim inate th e function of the floodplain that still exists in W a shington and push erosion and sedim e nt related problem s to the next river segm ent downstream. If however, it is determ ined that re-suspension of bank sedim e nt in Palm er Lake and Palm er Creek is increasing in-s tream arsenic con centrations, it would be appropriate to coordinate with upstream B.C. land m a nage m e nt agencies to discuss ups tream m e asures that would decrease floo ding in the Palm er Lake / Sim ilka m een River basin.

CCT 6. Based on the above, and on the fact that if the DOE is hoping to work with Canada on lowering arsenic levels on their section of the river, it seem s necessary to continue a more thorough and reliable arsenic m onitoring program than the one currently recomm ended in the draft report.

Response: We believe the proposed monitori ng program is appropriate f o r these purposes. T h e use of adaptive m a nagem e nt disc ussed in the report pr ovides the ab ility to respond through the TMDL to additiona l data as it becom e s available.

PageA-10 Similkameen River TMDL

# Appendix B

Technical Report

A Total Maxim u m Daily Load Evaluation for Arsenic in the Sim ilkameen River

Novem b er 2002

Ecology Publication Num b er 02-03-044

This publication may be viewed at the follow i ng w e bsite: http:// www .ecy.wa.gov/ bibli o /0203044.htm l



## Paper copy may be obt ained upon request



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Similkameen River TMDL PageB-1