## Chapt er One – Overvi ew

1.1 NEVADA’S CLASS I AREA – JARBIDGE WILDERNESS AREA

1.1.1 Geographic a nd Physiographic Setting 1.1.2 Visibility Impairm e nt 1.1.3 Observed Haze Events 1.1.3.1 W i ndblown Dust Events 1.1.3.2 Natural F i re Events



### 1.2 THE W E STERN REGIONAL AI R PARTNERSHIP AND NEVADA

1.3 TECHNICAL SUPPORT BACKGROUND

1.3.1 Regional Haze Monitoring Network 1.3.1.1 Overview of the IMPROVE Monitoring Network 1.3.1.2 IMPROVE Monitor JARB1 1.3.2 Em issions Analyses and Projections 1.3.2.1 Preparation of Ba seline Em issions Inventories 1.3.2.2 Projected 2018 Em issions Inventories 1.3.2.3 WRAP’s Technical Support System 1.3.3 Air Quality Modeling 1.3.3.1 Visibility Modeling 1.3.3.2 Source Apportionm ent Modeling



### 1.4 REFERENCES

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-11.1 NEVADA’S CLASS I AREA – JARBIDGE WILDERNESS AREA

Nevada has one m a ndatory Class I Area, the 113,167 acre Jarbidge W ilderness Area (Jarbidge W A ), locate d within th e Hum boldt Nationa l Fore st in the northeastern portion of Nevada, as shown on Figure 1-1.

FIGURE 1-1

LOCATION MAP SHOW I NG MANDAT OR Y CLASS I AREAS IN THE WRAP REGION

1.1.1 Geographic and Physiographic Setting

Much of the following discuss i on regarding the phys iograph i c and geo l o g ic setting o f Nevada is paraphrased from Stewart (1980). Nevada lies a lmost entirely within th e Great Basin portion of the Basin and Range physiographic province. The Basin and Range is characterized by a series of generally north-trending m ount ain ranges separated by alluvial valleys as shown on Figure 1- 2. A s m all portion along the western part of the state lies within the m ountainous S i erra Nevada

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-2province, and an area of moderate elevation and low relief along the northern border of the state is part of the Owyhee Upland adjacen t to th e Snak e River Plain of Idaho.

FIGURE 1-2

LOCATION MAP OF NE VADA AND P O RTI ONS OF ADJACE NT STATES

The m ountain ranges in Nevada are generally 5 to 15 m iles wide and rise 1,000 to 5,000 feet above the adjoining valleys, which are about as w i de as the mountain ranges. The m o untain ranges are typically elongate w ith m a ny extending m o re than 50 m iles in a north or north-east direction. T h e Basin an d Range top ography is th e result of extens ion block faulting and the basins have trapped continental sed i m e nt s derived from the adjacen t hig h lands.

Much of Nevada is an area of internal drainage . The large s t r i ver within the Great Ba sin, the Hum boldt, heads in the northeastern part of the s t ate, traverses westward and then southward to
term inate in the Hum bol dt and Carson Sinks in the western part of the state. Many of the basins in Nevada are floored by flat m ud-surfaced playas that are floo ded by runoff from the mountains during tim e s of high precipitation. P l ayas ar e sho w n on Figure 1-2 by the whitish areas in the western and southern por tions of the state.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-3Most of the unconsolid ated sedim e ntary m a te rial less th an six m illion ye ar s old f o rm s widespread alluvial fan, stream terrace, flood plain, valley flat and playa deposits. T h ese units grade f r om coarse gr avel near th e m o untains o r ra nges to f i ne silt and clay in the va lley and on the playas. Other sedim e ntary m a terial in this ag e span form s landslide, morainal, lacustrine, shoreline and eolian (i.e., carried, deposited or eroded by the wind) sand dune deposits.

During the P l eis t ocene, large in land lakes occup i ed m a ny of the present day broad valleys of Nevada as shown on Figure 1-3 by th e blue tint. Most of the play a deposits of Nevada represent part of the little-m odified bottom sedim e nts of these lakes. Wave-cut terraces and sand and gravel b each and bar dep o sits occur along what were th e shores of these lakes. The sandy lake

m a rgin deposits provided sand for many of the dune areas of the state.

FIGURE 1-3

EXTENT OF PLEISTOCENE LAKES IN THE GREAT BASIN

Map from Ken Ada m s, Desert Research Institute, 2008

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-4The Snake River Plain, a section of the Colum b ia Plateau, follows the Snake River across Idaho, stretching roughly 400 miles from th e W y om ing border to eastern Oregon (see Figure 1-4). The Snake River Plain is characterized b y plains and low hills co nsiderab ly lower and les s rugged than surrounding physiographic regi ons. Agriculture is the m a in land use of the Snake River Plain, with irrigated croplands, widespread livestock grazing a nd locally important feedlot and dairy operations. Note the proxim ity of this va st a g ricu ltur a l a r ea to th e Jarbidge W A , shown by the yellow sym bol in Figure 1-2.

FIGURE 1-4

LOCATION MAP OF S NAKE RIVER PLAIN

The following discussion of Nevada’s clim ate is paraphrased from N OAA (1985). Nevada’s principal clim atic features are bright sunshine, sm all annual precipitation, (averaging nine inches in the valleys and deserts) heavy snowfall in the higher m ountains, clean, dry air, and exceptionally large daily ranges of temperature W i de local variations of temp erature and rainfall

are comm on. The average annual number of days with precipitation of 0.01 inch or more varies considerably ; Las Vegas averages 23, Reno 49, Winnem u cca 67, Ely 72 an d Elko 78.

Nevada lies on the eastern, lee side of the Sierra N e vada Range, a m a ssive mountain barrier that

m a rkedly influences the clim ate of the state. The prevailing w i nds are from the west, and as the

warm moist air from the Pacific Ocean ascends th e western slopes of the Sierra Range, the air cools, condensation takes place a nd most of the moisture falls as precipitation. As th e air descends the eastern slope, it is warmed by com p r e ssion, and very little precipitation occurs. The effects of this m ountain barr ier are felt not only in the west but throughout the state, with the result that the lowlands of Nevadaare largely desert or steppes.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-5Jarbidge W A lies near the Idaho border ju st north of the physical geographic boundary separating the Colum b i a Plateau region, includi ng the Snake River Plain, and the Great Basin region to the south. It consists of the headwaters basin of the Jarb idge R i ver East Fork that flows north f r om the cente r of the wild erness area, and the headwaters ba sin of Marys River that flows south from t h e center of the wilderness area, part of the Columbia River/Great Basin hydrographic divide. The terrain encomp assed by the wilderness area consists of deep canyons with steep slopes. The Jarbidge River Canyon, wh ich com p rises the upper m a in headwaters of the Jarbidge River proper, is or iented south to north, with its mouth several m iles to the north where it d r ains into th e Bruneau River.

The area illu strates Nevada’s typ i cal basin and range topography (see Fig u re 1-5) with elevations ranging from 2,100 m ( 6,900 ft) where the Jarbidge River E a st Fork exit s the wilderness into Idaho’s Snake River Plains to eight peaks over 3,000 m (~10,000 ft) high along the Jarbidge Mountain crest, which includes th e highest peak, Marys River Peak at 3,170 m (10,398 ft). The varied terrain is cut by deep canyons with stee p slopes and supports a ra nge of vegetation zones from sagebrush flats to gl aciated alpine basins.

FIGURE 1-5

JARBIDGE W I LDE R NESS AR EA AND VICINITY

1.1.2 Visibility Impairmen t

Regional haze is pollution from disparate sources that im pairs visibility over a large region, including national parks, forests a nd wilderness areas. Of all the fe deral Class I areas, visibility was determ ined to be an important value at156. These 156 m a ndatory class I areas are the subject of the Regional Haze Rule (RHR). Re gi onal haze is caused by so urces and ac tivities

em itting f i ne particles a nd their prec ursors. Tho s e em issions are of ten tra n sported ov er la rge regions. Particles affect visi bility through the sca ttering and absorption of light, and fine particle s – p a rticle s sim ilar in siz e to the wavele ngth of light – are m o st efficient, per unit of

m a ss, at reducing vis i bility. Fine p a r tic les m a y either be em itted dire ctly o rf o rm ed f r om

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-6em issions of precursors, the m o st impor tant of which are sulf ur dioxide (SO 2 ) and nitrogen oxides (NO x ). Reducing fine particles in the atmos phere is generally considered to be an effective m e thod of reducing reg i onal haze, and thus improving visibility. It is also g e nerally considered that fine particles also adversely impact hum an health, esp ecially respirato r y and cardiov ascular system s.

Most visibility im pairm e nt occurs when pollution in the form of s m all particle s sca tte r or absorb light. Air pollutants com e from a variety of na tural and anthropogenic sources. Natural sources include windblown dust and sm oke from wildfi res. Anthropogenic sources include motor vehicles, electric utility and industrial fuel burning, and m a nu facturing operations. Higher concentrations of pollutants re su lt in more absorp tion and s cat tering of light, which reduce the clarity and color of a scene. Som e types of part icles, such as sulfates, are more effective at scattering light, particularly dur ing hum i d conditions. Other part icles like elem ental carbon from

com bustion processes are highly efficient at ab sorbing light. Commonl y, the re cepto r is the hum a n eye and the object m a y be a si ngle viewing target or a scene.

In the 156 m a ndatory Class I areas across the co untry, visual range has been substantially reduced by air pollution. In the W e st, visual range has decreased from an average of 140 m iles to 35-90 m iles. Much of the visibility im pair m e nt in the W e st can be attributed to natural

em issions of sm oke and dust with significant cont ributions resulting from international em issions from beyond the boundaries of the United States, includ ing Canada and Mexico.

Som e haze-causing pa rticle s are d i re ctly em itted to the a i r. O t hers a r e form ed when gases

em itted to th e air f o rm particle s as th ey are c a rr ie d m a ny m iles f r om the source of the pollutants. Som e haze form ing pollutants are also linked to hum a n health problem s and other en vironm ental dam a ge. In addition, particles such as nitrat es and sulfates contri bute to acid deposition potentially m a king lakes, rivers and stream s uns uitable for som e for m s of aquatic life and impacting flora in the ecosystem

. These sam e acid particles can also er o d e m a terials such as paint, buildings or other na tural and m a nmade structures.

1.1.3 Observed Haz e Events

Nevada regu larly experiences reg i onal haze ev ents due to natu ral em ission s of sm oke and dust. The Nevada Division of Environm ental Protectio n (NDEP) staff has witnessed num erous haze events due to fire and wind. The text below pr ovides som e anecdotal evidence and im ages of the significan ce of these haze events.

1.1.3.1 Windblow n Dust Events

Observed windblown dust even ts occur during at leas t two different m e teorological co nditions : unstable, well-m i xed atmosphere with high wind s; and unstable, highly-convective atm o sphere with very low winds. Examples are provided below.

Both of these windblown dust even ts occurred in the vicinity of Mill City, Nevada in Hum boldt County alon g the Hum b oldt River. Mill C ity is roughly m i d-way between Lovelock and W i nne mucca on I-80, or approxim a tely 30 m iles southwest o f W i nne m u c ca. The upp er im age of

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-7Figure 1-6 (looking northeast) shows a larg e plu m e of dust origin ating at the surface with a truck stop in the near background, while the lower im age shows the plum e m i xing higher into the
atm o sphere. This tru c k s t op is shown near th e lo wer center o f Figure 1-7 (i.e., ad jacen t to th e Highway 95 m a rker shown on the im age). Not e the textured area extending to the north and west of the highway across the Hu mboldt River valley. Th is is an area of activ e to sem i -active sand dunes dem onstrating eolian transport of sedim e nts parallel to the highway and is the source of the windblown dust shown in the figure. Fi gure 1-6 was taken on August 8, 2008 in the early evening.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-8FIGURE 1-6

AUGUST 2008 DUST EVENT NE AR MILL CITY, NEVADA

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-9FIGURE 1-7

SOUR CE AREA F O R OBSE RVE D DUST E V ENT

Figure 1-8 looks west and was taken m i dday A ugust 17, 2008. This image shows a group of dust devils originating from an area of sand dunes adjacent to the Hum boldt River approxim a tely 10

m iles north of the truck stop show n in the previous figure. Th e larg er of these dus t d e vils appears to b e transpo r tin g dust som e distan ce in to the atm o sphere. The relative significance of the contributions from this type of event to visibility impairment is not well docum ented or understood.

The dune fields supplying m a terial to these two dust events are an extensive m o saic of active,

sem i -active and stabilized sand dunes extending much of the di stance between Lovelock and W i nne mucca along th e sandy m a rgins of a large Pl eisto cene inland lak e (see Figure 1

- 3).

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-10FIGURE 1-8

AUGUST 2008 CONVECTIVE DUST EV ENT NEAR MILL CITY, NEVADA

In addition to the dust events described above, NDEP staff al so observed a regional dust event while driving from Twin Falls, Idaho to W e lls , Nevada on the m o rning of May 28, 2007. During this event strong northwest winds across the Snake River Plain resu lted in regional transport of particulate m a tter, possibly from loc a l sources as well as the Bureau Dune Field (Sm i th, 1982), located approxim a tely 80 m iles north of the Jarb idge WA near Mountain Hom e , Idaho. As the winds picked up during the m o rning, visibility pr ogressively and noticeably deteriorated over the Jarbidge Mountains and the ar ea of the Jarbidge WA visibl e from Highway 93 until the mountains were no longer visibl e. The distance from the hi ghway to the Jarbidge WA is approxim a tely 35 m iles.

These anecdotal exampl es of dust events suggest the impor tance of natural em issions contributions to visibility impair m e nt in the W e st.

1.1.3.2 Natural Fire Events

Em issions from natural f i re events are common c ontributors to visibility impairm ent at Class I areas throughout the W e st. The summ er of 2008 wa s a particularly bad fire year in northern California, when lightning storm s started num erous fires in early summer. The upper im age on Figure 1-9 is a sm oke-obscured view of Lake Tahoe from Mount Tallac, located within the Desolation W ilderness Area just over four m iles from the mouth of Em e r ald Bay and

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-11approxim a tely 6 m iles from the BLIS1 Interagency Monitoring of Protected Visual Environm ents (IMPROVE) m onitor represen tin g the Desola tion W ildern e ss Area.

The lower im age presents a sim ilar view of La ke Tahoe from Mount Ta llac created using Google Earth technology. Note the top of Mount Tallac in the lower left corner, the location of Cascade Lake in the near foreground, with Lake Tahoe and Em erald Bay in the m i d-background. The BLIS1 monitor is lo cated app r o x im ately two m iles north of Em erald Bay near the shore of Lake Tahoe. The im age was captured m i dday Ju ly 27, 2008, one of m a ny sm oke-obscured days experienced during the summ er of 2008 on the east slope of the Sierra due to California wildfires. T h is haze event was attrib uted to wild fires near Yosem ite National Park approxim a tely 100 m iles to the south southeast.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-12FIGURE 1-9

OBSE RVE D JULY 20 08 LAKE T AHOE SMOKE E V ENT

A sim ilarly intense sm oke event was also obser ved near the Nevada/Utah border while driving west between Delta, Utah and Ely, Nevada on Highway 50 in the vicinity of Great Basin National Park. W h ile approach ing the Nevada border from the east on Septem ber 17, 2007, the Snake Range, approxim a tely 30 m i les distant, w a s partially obscured by sm oke as shown by the

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-13upper im age in Figure 1-10, which was taken from inside a vehicle. The lower im age was recreated using Google Earth technology. The hi ghest point visible in the lower im age is Wheeler Peak, which is barely visible in the upper im age.

FIGURE 1-10

SEPTEMBE R 2007 RE GIONAL SMOKE EVENT EAST ERN NEVADA

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-14At Sacram ento Pass, where Highway 50 crosses th e Snake R a nge, visibility across Spring Valley

was comp letely obscured and there was a strong sm e ll of wood sm oke. This event was related to wildfires in southern California approxi m a tely 350 m iles to the southwest.

This anecdo t al ev idence of visibility im pair m e nt f

r om wildf i res emphasizes the ro le o f natural f i re in visibility im pairment, both f r o mlocal and distan t sour c e s.

1.2 THE WESTERN REGIONAL AI R PARTNERSHIP AND NEVADA

USEPA funded five Regional Planning Organiza tions throughout the country to coordinate regional haze rule-related activ it ies b e tween states in each reg i on. Nevada participates in the Western Regional Air Partnership (WRAP), the consensus organizati on of western states, tribes, and federal agencies, which oversees analyses of m onitoring data and pr eparation of technical reports reg a rding reg i onal haze in the western United States.

The W R AP was for m ed in Septem ber 1997 as th e successo r organization to the Gran d Canyon Visibility T r ansport Commission. It is adm i nistered jointly by the W e stern Governors Association (WGA) and the Nationa l Tribal Environm ental Council (NTEC). The m i s s ion of the WRAP is to identify regional or com m on air m a nagem e nt issues and to develop and implem e nt strategies to address thes e issues . The W R AP is a partnership of states and trib es as well as federal agencies and was designated by USEPA t o assist western states in the deve lop m ent of regional haze plans. It pr ovides a coordination m echanis m with regard to science and technology support for policy and programm a tic uses in the western United States.

WRAP m e mber states include Alaska, Arizona , California, Colorado, Idaho, Montana, New Mexico, North Dakota, Oregon, South Dakota, Utah, W a shi ngton, and Wyom ing. Federal participan ts are th e Depa rtm e nt of the Inte ri o r (N ationa l Park Service and Fish & W ildlif e Service,) the Departm e nt of Agriculture (Forest Service) and USEPA. Although Nevada is not a for m al m e mber, Nevada has been an activ e, c oop erative pa rticipant in the W R AP and in the forum s , wor kgroups and comm ittees that were form ed to address m a ny elem ents of this Regional Haze State Implem entation Plan (RH SIP).

Work by WRAP comm i ttees, forums and wor kgroups is accomp lished by the staff tim e contributed by state, tribal, Federal L a nd Mana ger (FLM), USEPA and environm ental, industry and public representatives, with the suppor t of WRAP staffing th rough WGA and NTEC. WRAP wor k is also handled thr ough contracts to environm ental co nsulting firm s, to analyze air pollution data collected by states and tribes in their regulatory program s as well as to prepare data and analyses for natural and/or u n contro llab l e air pollution sources.

The W R AP estab lished s t akehold e r-b ased technica l and policy oversight comm ittees to assist in

m a naging the developm ent of regional haze work products. Working gr oups and forum s were established to develop technical tools and work pr oducts the states and trib es needed to develop their im plem entation plans. Much of the W R AP’s effort focuse d on regional technical analysis, which is the basis for developi ng strategies to m e e t the RH R requirem e nt to dem onstrate reasonable progress towards natura l v i sibility con d itions in Cla ss I areas. This includes the

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-15comp ilation of e m ission inventories, air quali ty modeling and am bient m o nitoring and data analys is.

The W R AP has developed a regionally-consistent and comp arable body of technical data and analys is too l s that h a s been invalu able in addr essing regional haze in wes t . These data and tools are provided for use and evaluation through a tran sparent and open network of interrelated data support web system s and a techni cal decision support system :

WRAP Technical Data Support Centers

• Visibility Infor m ation Exchange W e b System ( http://vis ta.c ir a.colos t ate. e du/views/ ) : VIEW S provides on-lin e acces s to monitoring da ta, research results and special stud ies related to visibility.

• Causes of Haze Assessm ent ( http://w ww.coha.dri.edu/ ) : COHA provides a detailed analysis of ambient m oni toring d a ta f o r region al h aze in the WRAP region.

• Fire Em issions Tracking System ( http://www.wrapfets.org/ ) : FETS is a databas e with a web interface for tracking and m a naging pla nned and unplanned fire events. Users can view fire data on-screen with a m a pping t ool and query the database for downloads of data.

• Regional Modeling Center ( http://pah.cert.ucr.edu/aqm / 308/ ) : The W R AP’s RMC at the University of California Rivers ide provides state and tribal agencies with sophisticated modeling of regional haze and ot he r air qua lity p a ram e ters in the western United States.

• Em issions Data Managem e nt System ( http://wrapedm s.org/default_login.asp ) : ED MS is

an em ission inventory data warehouse for st ates and tribes. T h e system provides a consistent, comp lete and regional approach to em issions data m a nage m e nt and tracking.

WRAP Technical Decision Support System

• Technical Support System ( http://vis ta.cira.co lostate.edu /tss / ) : TSS integrates a num ber of different data support resources under one web-based decision support um brella for regional haze planning and imple m e n tation.

In addition to these technical tools and work products, the WRAP has provided a forum for coordination and consultation with other states, tribes and FL Ms. The m a jor am ount of interstate consultation in the developm ent of this SIP was through the Implem entation W o rk Group (IW G) of the W R AP. Nevada participated in the IW G, which took the products of the W R AP technical analysis and consultation process and developed a process for estab lish i ng reasonable progress goals in the western Class I areas. C h apter Nin e of this docum ent discusses the process that Nevada participated in to address the consulta tion requirem e nts with FL Ms, tribes and other WRAP states during the developm ent of this plan and Nevada’s comm it ments for future consultation.

1.3 TECHNICAL SUPPORT BACK GROUND

1.3.1 Regional Haz e Monitoring Netw ork

In response to the 1977 Clean Air Act Am endmen ts, the IMPROVE program was es tablished in 1985 to aid the creation of federal and state implem entation plans fo r the protection of visibility

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-16in Class I areas. Air m o nitoring devices at thes e locations are operated and m a intained through a for m al cooperative relationship betw een the USEP A and the National Park Service, U

. S. Fish and W ildlife Service, Bureau of Land Managem e nt and U.S. Forest Serv ice, collectiv ely called the FLMs. In 1991, several additional organizations joined the effort: State and Territorial Air Pollution Program Adm i nistrators/Association of Local Air P o llution Control Officials (recently

renam e d Na tional Association of Clean Air Agen cies), W e stern States Air Resources Council, Mid-Atlantic Regional Air Manage m e nt Association and N o rtheast States for Coordinated Air Use Managem e nt.

The IMPROVE program imple m ented an extensive long-term m onitoring program to establish the curr ent v i sibility con d itions, tr ac k changes in visibility an d determ ine causal m echanism for the vis i bility impairm e nt in the na tion a l parks a nd wildernes s a r eas. The da ta collec ted at the IMPROVE monitoring s ites are used by land m a nagers, industry planners, scientists, consultants, public interest groups and air qua lity regulators to better understa nd and protect the visual air quality resource in Class I areas. IMPROVE docum e nts the visual air quality in wilderness areas and national parks throughout the U n ited States.

1.3.1.1 Overview of the IMPR OVE Monitoring Network

The IMPROVE network focuses on rural areas in th e west er n Uni t e s St at es. Other visibility and aerosol m onitoring netw orks, such as that of the National W eather Se rvic e Airport Visibility Data, m a y focus on different air sheds and have different data collect ion objectives. In 1988, IMPROVE began with 20 m onitori ng sites. After publicatio n of the regional haze ru le in 1999, the first step in the im plem entation process was the upgrade and expansion of the IMPROVE network to 110 sites nationally. Figure 1-11 shows the current IMPROVE m onitoring network throughout the United States.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-17FIGURE 1-11

MAP OF I M PROVE MONITORI NG NE T W ORK IN T H E UNITED STATES

The IMPROVE network consists of aerosol and op tical samp lers. Every IMPROVE si te deploys

an aeroso l s a mp ler to measure sp eciated fine aeroso ls and coarse m a ss. Se lect sites also dep l oy a transm issometer and nep h elom eters to m easure li ght extinction and scattering respectively, as well as au to m a tic cam er a system s to visually m e as ure th e scene. Particul ate concentration data are obtained every third day over a 24-hour coll ection period and converted into reconstructed light extinction through a comp lex calculation usi ng the IMP R OVE equa tion that m a y be viewed
at: http://v ista.cir a.colos t ate.edu /im prove/Tools/ReconBext/reconBext.htm . Light extinction, the im pair m e nt of visibility, occurs due to part icles and gases that reflect and absorb light.

Reconstructed light extinction (denoted as b ext ) is expressed in units of inverse m e gam e ters (1/Mm or Mm -1 ). The RHR requires the tracking of visi bility conditions in term s of the Haze Index (HI) m e tric expressed in the deciview unit (40 CFR 51 .308(d)(2)). The relationship between light extinction in Mm -1 , Ha ze Index in dv and visual ra nge in km is indicated by the scale in Figure 1-12.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-18FIGURE 1-12

LIGHT EXTINCTION- HAZE INDEX-VISUAL RANGE S C ALE

The deciview is a unit o f m easurement of haze th at is d e sign ed so that un iform changes in haziness correspond approxim a tely to uniform in crem ental changes in perception across the entire rang e of condition s , f r om pristine to h i ghly impaired. More inf o r m ation regar d ing tracking visibility conditi ons is found in USEPA’s Guidance for Tracking Progress Under the Regional Haze Rule a t: http://www.epa.gov/ttn/oarpg/ t1/m e m oranda/rh_tpurhr_gd.pdf

. The IMPROVE data undergo extensive quality assu rance and control procedures and analyses by its con t ra cto r s and the N a tiona l Park Service b e f o re it is released. The aerosol and optical data

are m a de publicly available approxim ately nine months after collection. In addition, seasonal and annual data reports, special study data reports, technical pub lications and other data and analys is rep o rts are prep ared. IMPR OVE program resources are availab l e at: http://v ista. c ira.co lostate. edu/Improve

.

1.3.1.2 IMPROVE Monitor JARB1

Two operating IMPROVE m onitoring sites are located in Nevada, one at Great Basin National Park and the other at the Jarbidge W A . The W a lker River Pa iute Tr ibe, a third m onito ring site in Nevada, operated from June 2003 to Nove m b er 2005. The IMPROVE monitor representing the air qua lity at the Jarbidge W A is identified as JARB1.

JARB1 was am ong the fi rst 20 IMPROVE sites to start operation in 1988 and is sponsored by the U. S. Forest Service. Generally, JARB1 is expected to be repr esentative of aerosol characteristics in th e Jarbidge WA especially wh en the atm o s phere is well m i xed and regionally hom ogeneous. However, the site is at a low elevation in the Jarbidge R i ver Canyon that is separate from the Jarbidge W A and upper East F o rk of the Jarbi dge River. Consequently, the monitoring site m a y at tim e s be isolated from wilderness locations and potentially impacted by different local em ission sources. Figure 1-4 sh o w s the loca tion of the JARB1 m onitoring site by a bright green dot.

As does every IMPROVE site, JARB1 deploys an aer oso l s a mp ler to measure sp eciated aerosols and coarse m a ss. Along with ot her selected sites, JARB1 also has an au tom a tic camera sys t em to obtain a visual record, a tr ansm issom e ter to m easure light extinction, and a nephelom e ter to

m easure light scattering. Data from these samp ling devices are us ed to d e term ine the visibility status at the Jarbidge W A

.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-191.3.2 Emissions Analyses and Projections

USEPA’s RHR requires statewide em ission inve ntories of pollutants that are reasonab l y anticipated to cause or contribu te to visibility impairm e nt in any m a ndatory Class I area. Nevada’s inventories are presented in Chapter T h ree. These em issions in ventories are available from the WRAP TSS ( http://v ista. c ir a.colos t ate. e du/TSS/Results/Em i ssio n s.aspx ). The TSS webpage has links to m a ny references that desc ribe in detail the em issions m e thods used in developing the point, area, m obile, dust, o ffshore and fire em ission inventories.

Em issions scenarios used in the developm ent of this SIP represent actual baseline em issions (Base02), typical baseline em issions (Plan02), and projected em issions (Base18 and PRP18). The baseline period includes 2000 through 2004, represented by 2002, while the projected inventories denote 2018 em issions, as discussed below. The proj ected inventories take into account growth, “on-the-books” and “on-the-way” controls and re gulations and the application of regional h aze strategies. The year 2018 was select ed as it represen ts th e first m ilestone date for de m onstrating reasonable progress. These in ventories were used for visibility and source apportionm e n t m odeling.

The pollutan t s exam ined are SO 2 , sulf ur oxides (SO x ), NO x , volatile organic compound (VOC), prim ary organic aerosol (POA), elemental carbon (EC), fine pa rticula t e (P M fine), coa r se particulate (PM coarse) and ammonia (NH 3 ). It is im portant to note that each of these pollutants have char acteris tic s tha t dif f

e r in ter m s of ability to af f

ect vis i bility. Ass u m i ng one em ission unit of PM fine, for example, the sam e unit of SO 2 or NO x would be about three tim es m o re effective at impairing visibility. Organi c carbon is about four tim es m o r e effective and elem ental carbon about ten tim e s more effective at impairing visib ility. (Organic carbon is discussed in Chapter Four as part of the weighted em issions potential analysis.) Conve rsely, P M coarse is about half as effective as PM fine. Both VOC a nd NH 3 af f

e ct vis i bility only af ter c e r ta in chem ical reactions occur and, theref ore, cannot be comp ared in this manner.

1.3.2.1 Preparation of Baselin e Emissions Inventories

2002 Base Case (Base02) Inventory The Base02 inventory used actual data reported by states, locals, tribes and USEPA da tabases, which evolv e d from states’ actual em issions data subm itted to USEPA for the 2002 National Em ission Inventory. The W R AP Stationary Sources Joint Foru m contracted with Eastern Research Group (ERG) and subcontractors ENVI RON International Corporation and Alpine Geophysics to improve upon the 2002 W R AP e m issions inventory, particular ly for oil and gas

area sou r ces and for larg e point sou r ces on selected tribal lands. The docum ents describing this project can be reviewed in detail by selecting the following links:

• http://www.wrapair.org/foru m s /ssjf/docum ents/Pivot_Tables/2006- 01_REPORT_QA_of_the_2002_WRAP_S tationary_Sources%20EI.pdf

• http://wrap a ir.org/f o rum s /ssjf / docum ents/e ictts/OilGas/W RAP_Oil&Gas_ F inal_Repor t.1 22805.pdf

• http://www.wrapair.org/foru m s /fejf/doc um ents/WRAP_200 2_PhII_EI_Report_20050722 .pdf

.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-20The purpose of the Base02 scenario is to repres ent the actual conditions in calendar year 2002 with respe c t to am bient air qua lity an d the a ssoc i a t ed sourc e s of visibility

- i mp airing air pollutants. The Base02 em issions inventories we re used to v a lida t e the air quality m o del and associated d a tabas e s and to dem onstrate ac ceptable m odel perfor m a nce with respect to replicating observed particulate m a tter air qual ity. Version “a” of the 2002 base case inventory, Base02a, was developed based on prelim inary 2002 m odeling which can be reviewed in detail at http://pah.cert.ucr.edu/aqm / 308/reports /final/2002_MPE_report_m a in_body_FINAL.pdf

. Improved 2002 em issions data for the United States , Mexico and Canada were used to create a final base 2002 annual em issions database, Base 02b, for use in the Community Multi-Scale Air Quality (CMAQ) m o del and th e Comp rehensive Air Quality Model with Extens ion s (CAMx) model perform a nce evaluations. Actual 2002 fire em issions data were included in this Base02b inventory.

2000 Through 2004 Baseline-Period (Plan02) Inventory The 2000 through 2004 baseline period planning case em issions scenario is referred to as “Plan02”. As with the Base02 inventories, Plan02 has undergone a number of revisions and enhancem ents to arrive at the final versions used in visibility and source apportionm ent modeling. The Plan02 series of inventories was developed to represent baseline period

em issions patterns based on average, or “typ ical” conditions. The Plan02 inventory was developed from the Base02 em issions m odeling scenarios by incorporating:

1. Replacem e nt of actual 2002 fire em issions inventories with the baseline typical fire

em issions inventories; 2. Replacem e nt of the temporal profiles for la rge stationary point s ources with profiles developed from an average of several years surrounding 2002; and 3. Corrections to the off-road m obile, on-ro ad m obile, offshore Paci fic shipping lane and WRAP oil and gas inventories.

The inventory series Plan02a, Plan02b and Plan 02c provided a basis for comp arison with the future year 2018 projected em issions, as well as f o r gauging reasonable pr ogress with respect to future year visibility. The Plan02d em ission i nventory was based on the m i nor changes to the Plan02c em ission inventory. Thes e revisions to the Plan02c em ission inventory included:

1. Updating the current status of point sources related to the BA RT requirem e nts under the regional haze rule; and 2. Correcting erroneous or m i ssing Standard Industrial Classifica tion and/or source class i ficatio n codes (SCC).

The Plan02c inventory was used for source apportionm ent m o deli ng, whereas the P l an02d inventory was used for visibility m o deling and weighted em ission potentia l (WEP) analyses, as discussed in section 1.3.3.1 below.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-211.3.2.2 Projected 2018 Emissions Inventories

2018 Base Case (Base18) Inventory The 2018 future-year base case em issions scenar io is referred to as “2018 Base Case” or “Base18”. The Base18 em issions scenario is used to represent conditions in 2018 with respect to sources of visibility-imp airing air pollutants, taking into consider ation growth and controls. The Base18b inventory contained summ a r ies of 2018 stationary point and area source em i ssion inventories projected from the Pl an02c inventory and was initially comp leted by ERG in January 2006. ERG’ s report is available at http://www.wrapair.org/foru m s /ssjf/doc um ents/eictts/docs/WRAP_2018_ EI-Version_1- Report_Jan2006.pdf

. This inventory was used for source apportionm en t m odeling. Modeling results based on this

em ission inventory are used to define the future y ear am bient air quality a nd visibility m e trics.

The projection m e thodology incl uded the following steps:

1. Perm it Lim its: Adjusting pro j ec te d em i ssions downward in cases where the projected

em issions may have inad verten tly ex ceeded an enforceable em ission lim i t

. 2. Section §309 Flags: Point sources in the Grand Canyon Visibility T r ansport states whose 2002 facility-level SO 2 em issions were at least 100 tons /year were assigned section §309 flags. 3. Retirement and Replacement Rates: Effects of retirem ent were estim a ted using annual retirem e nt rates based on expected equipm en t lifetim es. Retired equipm ent was replaced by lower-em itting new e quipm ent. Unit lif etim es were exam ined for na tural gas-fired electric generating units (EGUs). No reti rem e nts were assumed for coal-f ired EGUs. 4. Control factors: Em ission reductions due to k nown (on-the-books) controls, consent decree reductions, SIP control m easures and ot her relevant regulations that have gone into effect since 2002, or will go in to effect before the end of 2018 (on-the-way). These controls do not include impacts from any future control scenarios that have yet to be determ ined. 5. Growth Factors: S CC-specific growth factors de veloped from the Econom i c Growth Analysis System (EGAS) projection factor m odel were included. 6. Adjustments: (a) Em issions for new fa cilities that have com e on-line since 2002, (b) Corrections for facilities th at retired in 2003 o r2004 and w ill not retu rn to operation in the future, and (c) Othe r (i. e ., ratios to corre ct ce rta i n PM 10 and PM 2. 5 em ission factors/S CCs for

com bustion of natural gas)

2018 Prelim inary Reasonable Progress (PRP18 ) Inventory Several enhancem ents and corrections were s ubsequently m a de to the 2018 Base18b inventory resulting in the PRP18a inventory. T h e W R AP region 2018 point and ar ea source inventory projections were updated from the 2018 Base18b i nventory with information from individual state air agencies. The PRP18a inventory was created to es tablish the most rep r esen tative source-specific em issions projectio ns data as the basis for prepar ing regional haze plans. The PRP18a inventory was used for visibility m ode ling. Developm ent of the PRP18a inventory is

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-22docum ented in a technical m e m o ava ilable at http://www.wrapair.org/foru m s /ssjf/docum en ts/eictts/Projections/PRP18_EI_tech%20m e m o_061 607.pdf

.

The PRP18a inventory revisions inclu d ed the follo wing elem ents: 1. Presumptive BART e m ission lim i t s were appl ied to BART-eligible coal-fired EGUs for SO 2 only and not for NO x . 2. Specific BART li m its for all co al-fired E GU sources subject to BART in Colorado, North Dakota and Utah, as well as one facility in Oregon. 2. Based on state and local agency co mment s, SCC codes were corrected and source inform ation was updated based on new sources, inactive sources and facility nam e changes. 3. For EGU f acilities rep o rting to USEPA’s Clean Air Markets Division’s acid rain database, EGU facility IDs were c o rrec t ed and m i ssing EGU source records were added. 4. Revised E GU projections of future coal-fir ed E GU construction: used E n ergy Inform ation Adm i nistration projections of 2018 energy requirem ents; determ ined existing WRAP region capacity to identify total new require m e nts ; added ex isting state and local agency EGU per m its; added 11 new “Model” 500MW EGU units operating at B A CT levels. Of the 11 proposed future coal-fired EGU plants, one is in Nevada. 5. Revisions to the W R AP Oil and Gas point and area sou r ce em i ssion inventory were incorporated based on work done by ENVIRON in 2007 ( http://www.wrapa ir.org/forum s/ogwg/docum ents/2007- 10_Phase_II_O&G_Final)Re port(v10-07%20rev.s).pdf )

. 6. Updates to the 2018 SO 2 em ission projections f o r Non-Utility Point sources were incorporated based on work done by Pechan and Associates in 2006 ( http ://wrap a ir.org / f o ru m s /ssjf / docum ents /eictts/Projections/Report-W R AP_SO2- oct11_Final.pdf ).

The Base18b inventory was used for source a pportionm ent modeling, whereas the PRP18a inventory was used for visibility m o deling and weighted em ission potentia l (WEP) analyses, as discussed in section 1.3.3.1 below.

1.3.2.3 WRAP’s Technical Su pport System

Air quality and visibility mode ling in support of regional haze pl anning in the W R AP region is the respon sibility of the W R AP Modeling Forum ’ s RMC. The RMC uses the air pollution

em issions data as described and displayed in the TSS Em issions Section to sim u late histor ic a i r quality conditions and estim ate th e benefit of em i ssions reductions program s in the future. The RMC uses regional gridded dispersion m odels for these sim u lations. The RMC web s ite ( http://pah.cert.ucr.edu/aqm / 308/ ) provides m odeling inputs and data results for review and download, using pre-set data pr ocessing, visualization and do wnload capabilities. The TSS provides key summary air quality and visibility modeling data through enhanced analysis and display tools.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-231.3.3 Air Quality Modeling

The sources of PM 2. 5 are difficult to quantify because of th e complex nature of their form ation, transport and rem oval from the atm o sphere. This m a kes it dif f icult to simply use em issions data to dete rm ine which pollu tants s hould be controlled to m o st effectively improve visibility. Photochem i cal air quality m odels offer opportu nity to better unders tand the sources of PM 2. 5 by sim u lating the em issions of pollutants and th e form ation, transport and deposition of PM 2. 5 . If an air quality model perfor m s well for an historical episode, the m odel m a y then be usef ul for identifying the sources of PM 2. 5 and helping to select the m o st effective em issions reduction strategies for attaining visibi lity goals. Although se veral types of air quality m odeling system s are available, the gridded, three-dim e nsional, Eu lerian m odels provide th e m o st comp lete spatial representation and the most comp r e hensive representation of pr ocesses affecting PM 2. 5 , especially f o r situ ations in which m u ltiple pollu ta nt source s in tera ct to f o r mPM 2. 5
.

The W R AP RMC utilized two regulatory air qual ity m odeling system s to conduct all regional haze m odeling. A brief discussion o f each of these m odels is provided below.

Community Multi-Scale Air Quality Model USEPA initially dev e lop e d the CMAQ m odeling system in the late 1990s. The m odel source code and supporting data can be downloaded from the Community Modeling and A n alysis System Cent er ( http://w ww.cm ascenter.org / ), which is funded by USEPA to distribute and provide lim ited support for CMAQ users. CMAQ wa s designed as a “one atm o sphere” modeling system to encomp ass m o deling of m u ltip le polluta nts and is sue s , includ ing ozone, PM, visibility and air toxics. This is in c ontrast to m a ny earlier air quality models that focused on singlepollutant issues (e.g., ozone m odeling by the Urba n Airshed Model). CMAQ is a Eulerian m odel -- tha t is, it is a grid -base d m odel in which the fram e of reference is a fixed, three-dim e nsional grid with uniform l y sized horiz on tal grid ce lls an d variab le v e rtical laye r thickne sses. The

num b er and size of grid cells a nd the num b er and thicknesses of layers are defined by the user, based in part on the size of the m odel i ng dom ain to be used for each m odeling pro j ect. The key science processes included in CMAQ are em i ssions, advection and dispersion, photochem i cal transform a tion, aerosol therm odyna m i cs and phase transfer, aqueous chem istry, and wet and dry deposition o f trace species. CMAQ offers a variet y of choices in the num erical algorith m s for treating m a ny of these processes, and it is designed so that new algorithms can be included in the model. CMAQ offers a choice of three photoc hem i cal m echanism s for solving gas-phase chem istry: the Regional Acid Deposition Mech anism version 2 (RADM2); a fixed coefficient version of the SAPRC90 m echanis m ; and the Carbon Bond IV m echanis m (CB-IV).

Comprehensive Air Quality Model with Extensions The CAMx model was initially developed by ENVI RON in the late 1990s as a nested-grid, gasphase, Eulerian photochem i cal grid model. ENVIR ON later revised CAMx to treat P M , visibility and air toxics. W h ile there are m a ny sim ilariti es between the CMAQ and CAMx system s, there are also some significant diffe rences in their treatm ent of advection, dispersion, aerosol for m ation, and dry and wet deposition.

In support of the W R AP regional haze air quali ty m odeling efforts, the RMC developed air quality m o deling inputs includ ing annual m e teorology and em i ssions inventories for a 2002 actual em issions base case, a plann i n g case to rep r esent the 20 00 through 2 004 regional haze

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-24baseline period using averages for key em issions categories, and a 2018 base case of projected

em issions determ ined using factors known at the end of 2005. All em ission inventories were developed using the Sparse Matrix O p erator Ke rnel Em issions (SMOKE) modeling system . Each of these inventories has under gone a num b er of revisions thr oughout the developm ent process to arriv e at the f i nal vers ion s used in C M AQ and CAMx air qua lity m odelin g. The deve lopm ent of each of these em ission scenarios is d o cum e nted under the em issions inventory sections of the TSS. In addition to various sensitivities s cenario s, the W R AP perf orm e d air quality model sim u lations for each of the em issions scenarios.

Initial conditions are specified by the user for the first day of a m odel sim u lation. For continental-scale m odeling using the Regiona l Planning Organization (RP O ) Unified 36-km dom a in, the initial conditions can affect m odel re sults for as m a ny as 15 days, although the effect typically becom e s very sm all after about 7 da ys. A m odel spin-up period is included in each sim u lation to elim inate any effects from the initial conditions. For the WRAP modeling, the annual sim u lation is divided into four quarter s, and included a 15-day spin-up period for the quarters beginning in April, July and October. For the quarter beginning in January 2002, a spinup period covering December 16-31, 2001, using m e te orology and em issions data developed for Central Regional Air Planning Asso ciation (CENRAP) were used.

Boundary conditions sp ecify the co ncentration s of gas and PM species at the four lateral boundaries of the m odel dom a in. Boundary cond itions d e term ine the a m ounts of gas and PM species that are transported in to the model dom a i n when wind flow is into the dom ain. Boundary conditions have a m u ch larger effect on m odel simulations than do ini tial conditions. For som e areas in the WRAP region and fo r clean conditions, the boundary c onditions can be a substantial contributor to visibility impairm ent.

For this study, boundary conditions data generated in an annual sim u lation of the global-scale GEOS-Che m m odel that was comp leted by Jacob et al. ( http://wwwas.harvard.edu/chem istry/trop/geos/ ) for calendar year 2002 were applied. Additional data processing of the GEOS- C he m data was require d before using them in CMAQ and CAMx. The data first had to be m a pped to the boundaries of the W R AP dom a in, and the gas and PM species had to be rem a pped to a set of species used in th e CMAQ and CAMx m o dels. This w o rk was

comp leted by Byun and coworkers ( http://wwwas.harvard.edu/chem istry/trop/geos/m eeti ngs/2005/ppt/Expanding_Model_Capabilities/GEOSCMAQ_april_4_Byun.ppt ).

The CMAQ model options and configuration used for the WRAP 36-km model sim u lations are described in Tonnesen et al. (2006) ( http://pah.cert.ucr.edu/ aqm / 308/reports/final/2002_M PE_report_m a in_body_FINAL.pdf ) . The RMC prepared a white paper describing the air quality m odeling preformed for W R AP, available
at http://vista.cira.colostate.edu/doc s/wrap/Modeling/AirQ ualityModeling.doc . The white paper provides detailed information rega rding the m ode ling software, data sources, developm ent and results of various m odel sim u lations, model perf orm a nce evaluation, visibility projections, PM source apportionm ent using Part icula t e Ma tte r Source Attribu ti on Tracking (PSAT) and m odel sensitivity simulations.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-251.3.3.1 Visibility Modeling

The RHR goals include achieving natural visibility conditions at 156 federally m a ndated Class I areas by 2064. In m o re specific terms, that goal is defined as visibility improvem e nt toward natural conditions for the 20 percen t of days that have the worst visibility (term e d “20 percent worst” visibility days), and no worsening in visi b ility f o r the 20 percen t of days that have the best visibility (“20 percent best” visibility days). One comp onent of the states’ dem onstration to USEPA that they are m a king reasonable progre ss toward this 2064 goal is the comp arison of modeled visibility projections for 2018 with what is term ed a uniform rate of progress (URP) from baseline to natural conditions by 2064.

Prelim inary 2018 visibility projections have been m a de using the Plan02d and PRP18a CMAQ 36-km modeling results, following USEPA guida nce that recommends applying the m o deling results in a relative sense to project f u ture -year visibility conditions (U.S. EPA, 2001, 2003a, 2006). Projections are m a de using relative resp onse factors (RRFs), which are defined as the ratio of the f u ture-y ear modeling re sults to th e c u rrent-yea r modeling re sults. The calculated RRFs are applied to the baseline obs erved vis i bil ity cond ition s to project f u ture-y ear o b served visibility. T h ese projections can then be used to a ssess th e ef f

ectiv eness o f the sim u lated

em ission control strategies that were included in the future-year m odeling. The m a jor features of USEPA’s recommended visibility projections are as follows (U.S. EPA, 2003a,b, 2006):

• Monitoring data should be used to define current air quality.

• Monitored concentrations of PM 10 are divided into six m a jor components; the first five

are assum e d to be PM 2. 5 and the sixth is PM 2. 5- 10
. o SO 4 (sulfate )

o NO 3 (partic u late n i trate)

o OC (organic carbon)

o EC (elem e ntal carbon)

o OF (other fine particulate or soil)

o CM (coarse m a tter).

• Models are used in a relative sense to devel op R R Fs between future and current predicted concentratio ns of each component.

• Component-specific RRFs are m u ltiplied by curr ent m onitored values to estim ate future

component concentrations.

• Estim ates of future com p onent concentrations are consolidated to pr ovide an estim a te of future air quality.

• Future es tim ated air quality is com p ared w ith the goal for reg i ona l haze to see whether the sim u lated control strategy woul d result in the goal being m e t.

• It is accep table to assume that all m easured su lfate is in the form of ammonium sulfate [(NH 4 ) 2 SO 4 ] and all p a rticulate nitrate is in the form of a mmonium nitrate [NH 4 NO 3 ].

RRFs calculated from modeling results can be used to project future-yea r visibility. For the
current m o deling efforts, RRFs are the ratio of the 2018 m odeling results to the 2002 modeling results and are specific to each Class I area and each PM species. RRFs are applied to the Baseline Condition observed PM species levels to project future-year PM levels, which are then used with th e IMPROVE extinction equation lis te d above to assess v i sib i lity. The following six steps are used to project future-year visibili ty for the 20 percent best and 20 percent worst

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-26visibility days (the discussion below is for 20 pe rcent worst days but also applies to 20 percent best days): 1. For each Class I area and each m onitored day, daily vis i bility is ranked u s ing IMPROVE data and IM PROVE extinction equ a tion for each year from the five-year b a seline perio d (2000-2004) to iden tify the 20 percen t worst visib ility days for each year. 2. Use an air quality m odel to sim u late a base -year period (ideally 2000-2004, but in reality just 2002) and a future year (e.g., 2018), then apply the resulting inform ation to develop Class-I-area-specific RRFs for each of the six co mponents of light extin ction in th e IMPROVE aerosol extinction equation. 3. Multip ly th e RRFs by the m easured 24-h PM data for each d a y from the 20 percen t worst days for each year from the five-year base line period to obtain projected future-year (2018) 24-h PM concentrations for the 20 percent worst days. 4. Compute the future-year daily extinction us ing the IMPROVE aerosol extinction equation and the projected P M concentrations for each of the 20 percent worst days in the five-year baseline from Step 3. 5. For each of the 20 percen t worst days within ea ch year of the five-year baseline, convert the f u ture -y ear da ily ex tincti on to units of deciview and average the daily deciview values within each of th e five years separate ly to obtain five year s of average deciview visibility for the 20 percent worst days. 6. Average the five years of average d e ciview vis i bility to ob tain the f u ture -y ear vis i bility Haze Index estim ate that is com p ar ed with the 20 18 progress goal.

For all of the W R AP Cl ass I areas, the RMC pe rfor m e d prelim inary 2018 visibility projections and comp ared them to the 2018 URP using th e Plan02d and PRP18a CMAQ m odel i ng results and the old and new IMPROVE equations.

1.3.3.2 Source Apportionment Modelin g

Impair m e nt of visibility in Class I areas is ca used by a com b ination of local air pollutants and regional pollutants that are tr ansported long distances. To de velop effective visibility improve m e nt strategies, the W R AP mem b er stat es and tribes need to know the relative contributions of local and transported pollutant s, and which em issions sources are significant contributors to visibility impairm ent at a given Class I area.

A variety of modeling and data an alysis m e thods can be used to perform s ource apportionm ent of the PM observed at a given receptor site. One m e thod is to imple m ent a m a ss-tracking algor ithm in the air quality m odel to explic itly tr ack for a given em issions source the chem ical transform a tions, transport and rem o val of the PM that was form ed fromthat source. Masstracking m e thods have been imple m ented in the CAMx air quality m odel as PSAT.

Source apportionm ent for regional haze pl anning was conducted using various m odeling techniques. The SO x /NO x Tracer an d Organic Aerosol Tracer were perfo r m e d using the region al PSAT air quality m odel. The W E P analysis incl uded the synthesis of em issions data and

m e teorological back trajectories. Th e PMF Recepto r Modeling and Causes of Dust analysis were

comp lex statistical exercises involving IMPROVE m onitoring data. Not all source apportionm e n t techniques were applied to all pollutants.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-27Particle Source Apportionment Tracking The m a in objective of ap plying CAMx/PSAT is to evaluate th e region al h aze air quality for conditions typical of the 2000 through 2004 ba seline period (Plan02c) and future-year 2018 (Base18b) conditions. These resu lts are used :

• To assess the contributions of differ e nt ge ographic source regions (e.g., states) and source

categories to current (2000-2004) an d future (2018) visibility im pair m e nt at Class I areas, in order to obtain improved unders tanding of the causes of the impairm ent and which states are in cluded in the area of influe nce of a given Class I area.

• To determ i n e which so urce categories con t ribu ting to th e area of influence for each Class I

area are changing, and by how m u ch, between the 2000 through 2004 and 2018 base cases. by varying only controllable anthropogenic em issions between the 2 PSAT sim u lations; and

• To identify the source regions and em issions categories that, if controlled to lower

em issions rates than the 2018 base case le vels, w ould produce the greatest visibility improve m e nts at a Class I area.

The PSAT perform s source apportionm ent based on user-defined source groups. A source group is the com b i n ation of a geographic source region and an em issions source category. Examples of source regions include states, nonattainm e nt areas and counties. Examples of source categories include m obile sources, biogenic sources and el evated point sources; PSA T can even focus on individual sources. The user defines a geographic source regi on m a p to specify the source regions of in teres t . He or she then inp u ts each sou r ce category as separate, gridded low-level

em issions and/or elevated-poin t -sou rce em ission s. The m ode l then determ ines each source group by overlaying the source categories on the source region m a p. PM source apportionm e n t modeling was perform e d for aerosol SO 4 and aerosol NO 3 and their relate d species (e.g., SO 2 , NO, NO 2 , HNO 3 , NH 3 , a nd NH 4) . The PSAT si mulations include 9 tracers, 18 source regions (see Table 1-1) and 6 sour ce groups (see Table 1-2).

TABLE 1-1

WR AP C A Mx/PSAT S OUR CE RE GIONS

Source Region ID Source Region Descrip t ion 1 Source Region ID Source Region Descrip t ion 1

1 Arizona (A Z) 10 South Dakota (SD) 2 California (CA) 11 Utah (UT) 3 Colorado (C O) 12 Washington (WA) 4 Idaho (ID) 13 Wyom ing (WY) 5 Montana (MT) 14 Pacific off-shore & Sea of Cortez (OF) 6 Nevada (NV) 15 CENRAP states (CE) 7 New Mexico (NM) 16 Eastern U.S., Gulf of Me xico, & Atlan tic Ocean (EA) 8 North Dakota (ND) 17 Mexico (MX) 9 Oregon (OR) 18 Canada (CN)

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-281 The abbreviations in parentheses are used to identify source regions in PSAT receptor bar plots.

TABLE 1-2

WR AP C A Mx/PSAT E M ISSIONS SOUR CE GROUP S

Emissions Source Gro ups Low

- level S o urces Elevated Sources

1 Low-level point sources (including stationary off-shore) Elevated po int sources(including stationary offshore) 2 Anthropogenic wildfires (WRAP onl y) Anthropogenic wild fires (WRAP onl y) 3 Total m obile (on-road, off-road, including planes, trains, ships in/near port, off-shore shipping) 4 Natural em i ssions (natural fire, W R AP only, biogenics) Natural em i ssions (natural fire, WRAP only, biogenics) 5 Non- W R AP wildfires (elevated fire sources in other RPOs) Non- W R AP wild fires (elevated fire sources in other RPOs) 6 Everything else (a rea sources, all dust, fugitive am monia, non-elevated fire sources in other RPOs)

The source apportionm ent m odel results ar e typically presented in two ways:

• Spatial plots showing the area of influence of a s ource group’s PM species contributions throughout the m odel dom a in, either at a given hourly-average point in tim e or averaged

over som e tim e interval (e.g., m onthly average).

• Receptor ba r plots show ing the rank order of source groupings that contribute to PM species at any given receptor si te. Th ese plo t s als o can be at a particula rp o int in tim e or averaged ov er selected tim e intervals

— for ex ample, the average source co ntribu tions f o r the 20 percent worst visibility days.

The prim ary products of the W R AP PSAT mode ling were receptor bar plots showing the

em ission source groups that contribute the m o st to the m odel grid cells containing each IMPROVE monitoring s ite and o t her recep tor s i tes iden tified by W R AP.

Two annual 36-km CAMx/PSAT model sim u lations were perform e d: one with the Plan02c typical-year baseline case and the other with the Base18b future-year case. It is expected that the states and tribes will us e these r e sults to asse s s th e sources th at contribu te to visib i lity impair m e nt at each Clas s I Area and to guide th e choice of e m ission control strategies. The RMC web site includes a full set of source apportionm e n t spatial plots and receptor bar plots for both Plan02b and Base18b. These graphical displays of the PSAT r e sults, as well as additional

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-29analyses of these results are available on the TSS under http://v ista. c ira.co lostate. edu/TSS/Results /SA.aspx

.

Additional infor m ation related to the CAMx air quality m odel and PSAT a pportionm ent algorithm can be found at http://vista.cira.colo state.edu/docs/wrap/a ttribution/PSATMethods.doc

. Weighted E m issions Potential The W E P was develop e d as a screen ing tool for states to decide which source regions have the potential to contribute to haze form ation at sp ecif i c Class I areas, based o n both the 2 002 and 2018 em issions invento r ies. This m e thod does no t produce h i ghly accu rate results because, unlike the air quality m o del and associated PSAT analysis, it doe s not account for chem istry and

rem oval processes. Instead, it relies on an integr ation of gridded em issions data, back trajectory residen ce tim e data, a one-over

- dis t ance f actor to approxim a te depos itio n and a nor m a lization o f the f i nal res u lts. Reside nce tim e ove r an area is indicative of gene ral flow patterns, but does not necessarily imply the area contributed significantly to haze at a given rece ptor. Therefore, users

are cau tioned to view th e W E P as one piece of a la rger, m o re comp rehensive weigh t of evidence analysis.

The em issions data used were the annual, 36km grid SMOKE-processed, m odel-ready em issions inventories provided by the W R AP RMC. The anal ysis was perform e d for nine pollutants (m aps were gener a ted f o r all b u t the last th ree) :

• Sulfur oxi des

• Nitrogen oxides

• Organic carbon

• Ele m ental carbon • Fine particulate m a tter

• Coarse particu l ate m a tter

• Ammonia

• Volatile or ganic ca rbo n

• Carbon m o noxide

The following source categories fo r each pollu ta nt were id entified and preserved through the analys is:

• Biogenic

• Natural f i r e

• Point

• Area

• WRAP oil and gas

• Off-shore • On-road mobile

• Off-road mobile

• Road dust

• Fugitive dust

• W i ndblown dust

• Anthropogenic fires.

The back trajecto r y resid e nce tim e s were pr ovided by the WRAP COHA. The COHA project used NOAA’s HYSPLIT m odel to generate eight b ack trajectories daily f o r each W R AP Class I area for the entire five-year baseline period (2000 through 20 04). From these individual trajectories, residence tim e fields were generated for one-degree latitude by one-degree longitude grid cells. R e sidence tim e anal ysis computes the amount of tim e (e.g., number of hours) or
percen t of tim e an air parcel is in a h o rizon t al grid cell. P l otted on a m a p, residence tim e is shown as percent of total hours in each gr id cell across the dom a in, thus allowing an interpretation of general air flow patterns for a given Class I area. The re sidence tim e fields for the 20 percent worst and best IMPR OVE- m onitored extinction days were selected for the W E P analys is to h i ghligh t the potential em issions s our ces during those specif ic periods. A ddition a l

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-30inform ation regarding back traj ectory m odeling can be found at http://vista.cira.colost ate.edu/docs/wrap/Modeling/ BackTrajectoryModeling.doc

.

The W E P analysis consisted of we ighting the annual gridded em i ssions (by pollutant and source category) by the worst and best extinction days residence tim es fo r the five-year baseline period. To account for deposition along the trajectories, the result was further weighted by a one-overdistan ce factor, m easured as the d i stance in km between the centro i d of each em issions grid cell and the centroid of the grid cell containing the Class I area mon itoring site under investigation. (The “hom e ” grid cell of the m onitoring site wa s weighted by one fourth of the 36km grid cell distance, or one-over-9km, to avoi d a larg e respo n se in th at g r id ce ll. ) The resulting weighted

em issions field was norm a lized by the highe st grid cell to ease interpretation.

The W E P is not a rigorous, stand-alone analysis , but a simp le, straightforward use of existing data. As such, there are severa l caveats to keep in m i nd when using W E P results as part of a

comp rehensive weight of evidence an alysis :

• This analysis does not take into account any em issions chem istry.

• While actual em issions m a y vary considerably throughout the year, this analysis pairs up annual em issions data with 20 percent worst/bes t extinction days residence tim es – this is likely m o st problem atic for carbon and dust em issions, which can be highly episodic.

• Coarse particle and som e fine particle dus t em issions tend not to be transported long distan ces du e to their large m a ss.

• The W E P results a r e un itless num bers, norm a lize d to the larg est-va lued g r id ce ll. Effective use of these results requires an understanding of ac tual em issions values and their relative contributio n to haze at a given Clas s I area.

Additional infor m ation regarding W E P analysis can be found at http://vista.cira.colo state.edu/docs/wrap/attribution/W E PMethods.doc

.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-31

### 1.4 REFERENCES

NOAA, 1985. Clim ate Narrative of the St ates-V olum e 1. Ga le Research Comp any.

R.S.U. Sm it h, “Sand Dunes in the North Am erican Deserts.” in G. Bender(ed.), Reference Handbook of the Deserts of North Am erica, Greenwood Press, W e stport, Conn., 1982. pp. 481- 554.

J.H. Stewart, Geology of Nevada: Special Pub lication 4. Nevada Bureau of Mines and Geology, 1980.

WRAP 2002. Visibility Model Pe rfo r m a nce Evaluation

- Final Re port. W e stern Regional Air Partnership, February 24, 2006.

NEVADA REGIONAL HAZE S T ATE IMPLEMENTATI ON PLAN, October 2009 1-32