Utah Area Designation 

Recommendations for the 

2008 Ozone NAAQS 

State of Utah 

Department of Environmental Quality 

Division of Air Quality 

150 North 1950 West 

P.O. Box 144280 

Salt Lake City, Utah 84114-4820 

801-536-4000 

March 2009 
2

Table of Contents 

Purpose............................................................................................................................................ 4 

Overview of Ozone in Utah ............................................................................................................ 4 

Regional Ozone............................................................................................................................... 8 

Regulatory Background ................................................................................................................ 10 

Applicable Guidance..................................................................................................................... 11 

Document Organization................................................................................................................ 12 

Discussion of EPA Guidance Factors........................................................................................... 12

 Factor 1: Air Quality Monitoring Data ............................................................................... 12 

 Factor 2: Emission Data...................................................................................................... 15 

 Factor 3: Population Density .............................................................................................. 18 

 Factor 4. Traffic and Commuting Patterns ......................................................................... 20 

 Factor 5. Growth Rates and Patterns................................................................................... 22 

 Factor 6. Meteorology......................................................................................................... 24 

 Factor 7. Geography/Topography....................................................................................... 25 

 Factor 8. Jurisdictional Boundaries..................................................................................... 28 

 Factor 9. Level of Control of Emission Sources................................................................. 32 

Consideration of Additional Areas outside the Wasatch Front Core Area................................... 35 

 Park City, Summit County................................................................................................... 35 

 Heber Valley, Wasatch County............................................................................................ 37 

 Tooele Valley, Tooele County............................................................................................. 38 

 Brigham City, Box Elder County......................................................................................... 40

Utah County............................................................................................41 

 St. George, Washington County .......................................................................................... 43 

 San Juan County .................................................................................................................. 44 

State Recommendations................................................................................................................ 47 

 Wasatch Front ...................................................................................................................... 47 

 Attainment/Unclassifiable Areas ......................................................................................... 48 

 Summary Table.................................................................................................................... 49 

Supporting Documentation ........................................................................................................... 50 

 For nonattainment areas:...................................................................................................... 50 

 For attainment/unclassifiable and nonattainment areas:...................................................... 50

Names of contacts......................................................................................................................... 51

Appendix 1.................................................................................................................................... 52

Appendix 2.................................................................................................................................... 54 
3

Table of Figures 

Figure 1. Utah’s Wasatch Front ....................................................................................................5 

Figure 2. Population Density in Utah ........................................................................................... 6 

Figure 3. Population Density with CSA and MSA Overlay ..........................................................6 

Figure 4. Mean Summertime Afternoon Surface Background Ozone Concentration...................8 

Figure 5. Utah’s Air Monitoring Network...................................................................................13 

Figure 6. Percentage of VOC and NOx produced along the Wasatch Front................................16 

Figure 7. VOC Projections through 2014 ....................................................................................17 

Figure 8. NOx Projections through 2014......................................................................................17 

Figure 9. Population Density (Wasatch Front) with Counties and Topography..........................19 

Figure 10. Population Density and Area Roadways ......................................................................22 

Figure 11. Wasatch Front Topography ..........................................................................................26

Figure 12. Emissions in Relation to the Core Nonattainment .......................................................34 

Figure 13. Oil and Gas Production in San Juan County, Utah .....................................................45 

Figure 14. Recommended Ozone Nonattainment Areas................................................................47 

Figure 15: Statewide Area Map .....................................................................................................48 

Table of Tables 

Table 1. Ozone Concentrations from Official Utah DAQ Monitors ..........................................14 

Table 2. Ozone Concentrations from National Park Service (CASTNet) Monitors ...................15 

Table 3. Ozone Precursor Emissions ...........................................................................................15 

Table 4. Population Densities in Counties being considered as potential candidates for 

 Nonattainment Areas ....................................................................................................18 

Table 5. Traffic and Commuting Patterns ...................................................................................20

Table 6. Projected Population Growth (2000-2020) ...................................................................23 

Table 7. Projected Annual VMT Growth in Greater Wasatch Front Area (Millions) ................24 

Table 8. Elevations of Valley Floor and Adjacent Mountains along the Wasatch Front ............27 

Table 9. Description of all Areas of Utah and Recommended Designations .............................49 

Table 10. DAQ Monitor Network Locations ...............................................................................50 

 

 
4

Purpose 

The purpose of this document is to provide Utah’s recommendation regarding area designations for 

the revised National Ambient Air Quality Standard (NAAQS) for ozone which was developed under 

section 109 of the Clean Air Act (CAA) on March 12, 2008. 

Overview of Ozone in Utah 

The occurrence of ozone in the State of Utah should be considered on a regional basis. In 

general, higher concentrations of ozone are monitored in certain core areas where the majority of 

Utah’s population resides and where most major industry is located. These core areas are also 

where high local and interstate vehicular traffic predominate. In Utah, this core area is part of a 

geographical megalopolis region, better known as the Wasatch Front, extending from the Ogden 

area in Weber County on the north to the Provo area in Utah County on the south, a distance of 

approximately 90 miles. This area is bounded on the east by the Wasatch Range and on the west 

by smaller north-south mountain ranges and the Great Basin. The Wasatch Range is actually an 

extension of the Northern Rocky Mountains which extends southward to Mount Nebo, in 

southern Utah County. 

The yearly trend of NAAQS exceedances for ozone during the last twenty years shows a decline 

in ozone. This trend has occurred at the same time that the federal standard has twice been 

tightened. During this same timeframe, counties along the Wasatch Front maintained the 

applicable standard, if only by the slightest of margins. Ambient ozone data collected in recent 

years indicates that the 2008 8-hr standard is routinely exceeded at some monitors located within 

the state’s Wasatch Front core area monitoring network, while other monitors located in more 

peripheral locations along the Wasatch Front do not show violations. This reflects the State’s 

supposition that ozone generated in the major core area of the Wasatch Front actually moves 

throughout the area and is the probable cause for increased ozone concentrations being recorded 

in some peripheral locations along the Wasatch Front. A further discussion of this phenomenon 

can be found later in this document. 

Data collected along the Wasatch Front also indicate that ozone is a seasonal problem, 

characterized by episodic elevated concentrations during the summer months, usually June 

through August when temperatures routinely approach or exceed one hundred degrees 

Fahrenheit. These episodes generally occur during periods of stagnant high pressure associated 

with calm or very light wind conditions and a very stable atmosphere that acts to inhibit any 

substantial vertical movement of the air. Under these conditions, ozone begins to form in areas 

where significant emissions of volatile organic compounds (VOC) and oxides of nitrogen (NOx), 

most prevalent in Salt Lake and Davis Counties, combine in the presence of strong solar heating. 

Ozone concentrations along the Wasatch Front generally increase from mid-to-late morning until 

late afternoon when solar intensity reaches its maximum. As the solar intensity begins to subside 

and evening rush hour traffic increases, data suggests that some of the ozone is scavenged by 

NOx and concentrations begin to decrease. Ozone concentrations generally remain at relatively 

low levels throughout the night and begin to increase the following morning after the rush hour 

traffic subsides. If high temperatures and light winds persist over a period of two to three days, 

ozone can continue to form and accumulate along the Wasatch Front core area where it is 
5

contained vertically by nighttime subsidence and horizontally by the local topography as shown 

in Figure 1 below. 

Data from both Utah Division of Air Quality (DAQ) and National Park Service (NPS) monitors 

located in more rural and remote areas of the state show lower concentrations of ozone than 

those recorded along the Wasatch Front. In many cases, these remote concentrations are 

substantially lower, and reflect a normal regional background level of ozone. At times, however, 

the regional background level of ozone may increase due to ozone transport or as a result of 

wildfires during the summer season. A reasonable conclusion from available remote monitoring 

data is that the NAAQS is not exceeded outside of the urbanized or semi-urbanized counties that 

make up the Wasatch Front. 

Ozone is formed by a chemical interaction of VOCs and NOx in the presence of intense sunlight. 

Winds that occur during stagnant periods are generally of the diurnal mountain-valley variety, or 

very light breezes that flow generally north-south along the Wasatch Front. On many occasions 

under these conditions, areas of higher ozone concentration have been transported by these local 

breezes. By tracking daily ozone concentrations at various locations along the Wasatch Front, it 

has been noted that these concentrations increase and decrease in patterns that are consistent with 

local wind flows. For example, with a light southerly flow, concentrations that were originally 

higher in Utah or Salt Lake Counties tended to decrease while concentrations that were originally 

lower in Weber and Box Elder Counties tended to increase. With a light northerly flow, the 

opposite effect was noted (i.e., concentrations at northern monitors tended to decrease while 

concentrations at southern monitors tended to increase). The same phenomenon is true for light 

 

Figure 1. Utah’s Wasatch Front extending from Utah County (Lower right) to Box Elder County 

(Upper left). 
6

diurnal southeast-northwest flows. This local mesoscale transport of ozone along the Wasatch 

Front also accounts for higher concentrations of ozone being monitored in peripheral areas 

adjacent to the Wasatch Front core areas where neither sources of VOC nor NOx in amounts 

necessary to form ozone are found. 

 * Combined Statistical Area & Metropolitan Statistical Areas 

 Figure 2. Population Density of Utah Figure 3. Population Density w/CSA & MSA* 

Ozone is generally considered an urban pollutant since the precursors needed to form it are 

present in most urban environments and are generally not present in rural environments. This 

serves to highlight the distinction between urban areas that generally cause pollution and rural 

areas that may or may not contribute to the ozone problem. Much of this phenomenon is also due 

to the fact that the bulk of Utah’s population is generally located within lowland valley areas 

along the Wasatch Front in which air is easily trapped either by meteorological conditions or 

local topography. In other words, it is not enough to simply have an urban area with an urban 

mix of emissions; there must also be some barrier to dispersion which allows ozone 

concentrations to build up over a period of time and reach concentrations that eventually exceed 

the NAAQS. 

 

The foregoing characterization of Utah’s ozone problem has shaped the State’s approach to 

making these area designations. The vast majority of Utah is sparsely populated (see Figure 2). 

Most of the monitoring data has been collected in the heavily populated urbanized areas of the 

state. This suggests that most of the areas recommended for designation as either 

“attainment/unclassifiable” will be either in the rural areas of the state or in areas where 

precursors of ozone are not generated. Those areas recommended for the “nonattainment” 

designation will be urban areas where most of the sources of ozone precursors are found. 

However, our modeling domain will be much larger and will include all point sources within the 

modeling domain. 
7

Some distinctions have been made in the Environmental Protection Agency (EPA) guidance 

document regarding urban versus rural areas, relating to the presumptive boundaries of 

nonattainment areas and to the level of assessment required in the case of a departure from the 

presumption. Urban areas are generally considered to be metropolitan areas surrounding core 

cities, whereas rural areas would be other areas not included in or adjacent to urban areas. In 

Utah there are several instances where both urban and rural areas can be found within a single 

Metropolitan Statistical Areas (MSA). In many of these instances urban and rural areas have no 

actual affect on each other. Reasons for this are significant separation due to topographical 

features and large areas of sparsely populated desert or rangeland, and very large MSAs. Figure 

3 displays the population density shown in Figure 2 and also includes an overlay of the MSAs 

that comprise most of the counties of northern Utah. The Salt Lake-Ogden-Clearfield Combined 

Statistical Area (CSA) combines the Salt Lake City MSA, the Ogden-Clearfield MSA, the 

Brigham City Micropolitan Statistical Area (Box Elder County), and the Heber Micropolitan 

Statistical Area (Wasatch County). 

The most noticeable feature of these CSAs and MSAs is their size. The Salt Lake-OgdenClearfield CSA contains eight counties and covers 19,819 square miles (larger than nine US 

states). It extends east/west from the Nevada border to the southern Wyoming border, a distance 

of over 220 miles, and south from the Idaho border approximately 100 miles. The Provo/Orem 

MSA contains two counties and covers an east west distance of 170 miles. Each of these MSAs 

includes densely populated areas, sparsely populated areas, and very large areas with no 

population at all. The sparse or unpopulated areas are due to extended desert in the west and 

extreme mountainous terrain in the east. The largest concentration of both population and 

industry is found in the low valleys west of and adjacent to the Wasatch Front. Smaller 

concentrations of population are also found in some of the higher valleys east of the Wasatch 

Range, but there are generally few or no major industrial sources located in these areas. For the 

reasons cited above, and for additional reasons that will be presented later, Utah feels it is more 

appropriate to designate nonattainment areas based on the core urban area rather than MSA or 

CSA boundaries. 

 

The Cache County MSA located in northern Utah should be considered as an entirely separate 

entity as it is separated from the Wasatch Front by the northern extension of the Wasatch Front 

Range and is mainly influenced by separate meteorological and topographical factors. In 

addition, as we will see later in the monitoring section of this document, Cache County is 

currently in attainment with the ozone standard and always has been. For these reasons Cache 

County should be treated independently and not be considered as part of the greater Wasatch 

Front metropolitan area. 

The St. George MSA, comprised of Washington County, is located in the extreme southwest 

corner of Utah. Like Cache County to the north, Washington County is influenced by an entirely 

separate air shed. The National Park Service operates an ozone monitor at the entrance to Zion 

National Park, and based on 2006-2008 data from that monitor, Washington County is currently 

attaining the ozone standard. Washington County air quality will be further discussed later in this 

report. 

San Juan County, located in the southeast corner of Utah, is another area of the state that will 

also be discussed in this report. 
8

Regional Ozone 

Over the past few decades it has become apparent that ground level ozone is not just a local city 

or urban area problem, but a regional problem. Several studies have found that ozone is present 

in most areas of the country, even where precursors to ozone are not present. Transport (global 

and regional) of ozone has been found to be the mechanism that spreads or distributes the ozone 

from urban source areas, where precursors are readily available, to more rural areas where no 

anthropogenic precursors are available. Some of the monitored ozone concentrations were 

attributable to regional background concentrations and, in some instances, portions of total 

monitored ozone concentrations have been traced to areas along the U.S. West Coast or even 

Asia. Additionally, smoke from wildfires, from both within the Intermountain Region and from 

as far away as California has been found to impact local and regional ozone concentrations. The 

overall effect of this transport is a general concentration of ozone over a large regional area. 

In 2001, a Harvard University study1

 was conducted to estimate background ozone 

concentrations that would exist in the absence of anthropogenic emissions in the surface air over 

the United States using Global 3-D modeling. They found that these concentrations generally 

varied from 25–45 ppb, with the highest concentrations found over the Intermountain West 

region. A depiction of the mean summertime ozone variation across the United States is shown 

in Figure 4. 

 Figure 4. Mean summertime afternoon surface background ozone concentrations 

__________________________ 

1. “Estimating Background Ozone in Surface Air over the United States with Global 3-D 

Modeling of Tropospheric Chemistry,” Fiore, A.M. & Jacob, D.J., Harvard University Modeling 

Group, 2001. 
9

In addition, this study made the following conclusions: 

• Stratospheric mixing generally accounts for 1-5 ppb of the mean afternoon surface ozone 

concentration. 

• Hemispheric transport from both Asian and European sources can range from 

 5-12 ppb and generally occurs at intermediate ozone concentrations of 50-70 ppb. 

• Regional ozone concentrations range from 8-30 ppb and are very site specific. 

• Overall background ozone varies from 20-40 ppb. Higher concentrations of background 

ozone are generally found at higher elevations in the Intermountain West. 

In 2003, a group of scientists used an aerosol analysis model to study the transport of air masses 

infused with biomass materials from Siberia to North America.2

 Transport of these air masses to 

North America was confirmed by aircraft and surface observations. The group’s findings include 

the following: 

• Siberian biomass fires impacted both CO and ozone concentrations over a wide region of 

western North America and contributed to exceedances of the ozone air quality standard 

in the Pacific Northwest. 

• Modeled calculation enhancements for ozone were 2-6 parts per billion (ppb) above 

normal expected concentrations and were consistent with local observations of 5-9 ppb. 

The average enhancement during periods of low altitude intrusion resulted in 

observations 9-17 ppb above the normal expected concentration, depending on the site. 

• Regression analysis estimated that the Siberian biomass fires contributed 14-15 percent 

of the total ozone concentrations recorded during high ozone episodes. 

In 2006, WESTAR conducted a study3

 to quantify the amount of ozone attributable to 1) natural 

background ozone, 2) transported anthropogenic ozone, and 3) locally generated anthropogenic 

ozone for certain large metropolitan areas in the western United States. The results for Salt Lake 

City showed that during periods with an average peak 8-hour ozone concentration of 91 ppb, 

35 ppb were attributable to background ozone, 22 ppb were attributable to transported 

anthropogenic ozone, and 35 ppb were locally generated ozone. Similarly, during periods with 

an average peak 8-hour ozone concentration of 77 ppb, 35 ppb were attributable to background 

ozone, 20 ppb were attributable to transported anthropogenic ozone, and 22 ppb were attributable 

to locally generated ozone. 

 

From these three studies one could conclude that: 

• There is a regional background concentration of ozone present throughout the entire 

Intermountain West; 

• Ozone concentrations in the Intermountain West may be a regional concern; 

___________________________ 

2. “Long-range Transport of Siberian Biomass Burning Emissions and Impacts on Surface 

Ozone in Western North America,” Dan Jaffe et.al, Geophysical Research Letters, Vol. 31, 2004 

3. “Regional and Local Contributions to Peak Local Ozone Concentrations in Six Western 

Cities,” Sonoma Technology, Petaluma, California, STI-906004-2970-FR, Final Report prepared 

for the Western States Air Resources Council, May 30, 2006 
10

• Both transport of ozone and smoke from fires affects locally monitored ozone 

concentrations; and 

• The actual amount that transport and wildfires contribute to the overall ozone 

concentration for a given location varies greatly, and is difficult to quantify except in 

very specific instances. 

Regulatory Background 

On March 12, 2008, the EPA promulgated revisions to the NAAQS for ground level ozone. It 

revised the 8-hour primary (health based) ozone standard to a level of 75 ppb. The previous 

standard, set in 1997, was 80 ppb. Additionally, the EPA specified the level of the primary standard 

to three decimal places, thereby eliminating the rounding convention that was present in the previous 

standard. The EPA also revised the 8-hour secondary (welfare based) ozone standard to be identical 

to the revised primary standard. 

Section 107(d) of the CAA establishes that it is incumbent on each state to recommend initial 

designations for all areas within its respective geographic boundary following promulgation of a new 

or revised NAAQS. States are required to submit these recommendations to EPA, based on the most 

current three year data set, not later than one year after the promulgation of the new or revised 

standard. 

Areas should be designated as attainment, nonattainment, or unclassifiable. The Act allows that areas 

may be designated as: 

 (a) attainment, for any area other than an area identified in clause (b) that meets the 

 national primary or secondary ambient air quality standard for the pollutant; or 

 (b) nonattainment, for any area that does not meet (or that contributes to ambient air 

 quality in a nearby area that does not meet) the national primary or secondary ambient air 

 quality standard for the pollutant; or 

(c) unclassifiable, for any area that cannot be classified on the basis of available information 

as meeting or not meeting the national primary or secondary ambient air quality standard for 

the pollutant. 

EPA must finalize the area designations as expeditiously as practicable, but not later than two years 

following the effective date of the revised NAAQS. In the event that EPA intends to promulgate a 

designation that deviates from the State’s recommendation, it must notify the State at least 120 days 

prior to promulgating the modified designation to provide the State an opportunity to comment. The 

EPA’s designation of areas for the 8-hour ozone NAAQS will be based on the most current three 

consecutive years of air quality data at the time of the final designation.4 

____________________ 

4. For the 8-hour ozone NAAQS, it is the three consecutive years of data obtained in accordance 

with 40 CFR part 50, Appendix I; data used will be quality-assured and meet 40 CFR part 58 

requirements (e.g., for monitor siting). Recommended designations should generally be made based 

on 2006-2008 monitored air quality data and final designations on 2007-2009 data. 
11

Applicable Guidance 

On December 4, 2008, EPA issued a guidance memorandum5 to assist States and Tribes in making 

their recommendations with respect to ozone. The memorandum recommended that Core 

Based Statistical Areas (CBSA) or Combined Statistical Areas (CSA) serve as the presumptive 

boundary for evaluating the geographic boundaries of an ozone nonattainment area. This 

recommendation reflected a generic assumption that violations of the ozone NAAQS in urban areas 

may be attributed to contributions from sources distributed throughout the MSA based upon 

population density, traffic & commuting patterns, commercial development, and area growth. 

Current CSAs and MSAs in the State of Utah and the counties that are included in these areas are as 

follows: 

• Logan MSA 

 Cache County, Utah and Franklin County, Idaho 

• Salt Lake-Ogden-Clearfield CSA 

 Box Elder County 

Davis County 

 Morgan County 

 Salt Lake County 

 Summit County 

 Tooele County 

 Wasatch County 

 Weber County 

• Provo Orem MSA 

 Juab County 

 Utah County 

• St. George MSA 

 Washington County 

Section 107(d) of the CAA addresses the determination of whether an area is to be designated 

nonattainment. With respect to the 8-hour ozone NAAQS, all areas are to be designated 

nonattainment if they do not meet the standard or contribute to ambient air quality in a nearby area 

that does not meet the standard. The guidance memorandum further stated that EPA would consider 

requests for urban nonattainment area definitions that deviate from the MSA or C/MSA boundary 

definitions on a case-by-case basis, considering the following factors: 

1. Air Quality monitoring data 

2. Emissions data 

3. Population density and degree of urbanization including commercial development 

 significantly different from surrounding areas 

4. Traffic and commuting patterns 

5 Growth rates and patterns 

6. Meteorology (weather /transport patterns) 

7. Geography/Topography (mountain ranges or other air basin boundaries) 

8. Jurisdictional boundaries (existing ozone areas) 

9. Level of control of emission sources 

________________________________________ 

5. “Area Designations for the 2008 Revised Ozone National Ambient Air Quality Standards,” 

Memorandum from Robert Meyers dated December 4, 2008 
12

Document Organization 

Utah’s recommendations concerning area designations for the revised National Ambient Air 

Quality Standard for ozone will be presented at the end of this document. Generally speaking, 

rural areas recommended for designation as “attainment” or “unclassifiable” will be described by 

county. Exceptions to this approach will include Tribal Lands and portions of counties that 

contain nonattainment areas. 

Since the description of Utah’s nonattainment areas located in urban areas will deviate somewhat 

from the presumptions outlined in the EPA guidance memoranda, the recommendations will 

need to be supported by considering the nine factors identified in that guidance. The next 

portion of this document addresses those nine factors. 

 

It should also be kept in mind that the recommendations presented herein represent Utah’s 

preliminary assessment of the spatial distribution of its ozone problem. As actual work proceeds 

on the implementation plan necessary to address the problem, Utah reserves the right to 

recommend modifications to the nonattainment area boundaries. Utah will include emission 

sources outside of the nonattainment area in the control strategies as has been done in prior state 

implementation plans (SIP) that have been approved by the EPA, and were successful in meeting 

the NAAQS. 

Discussion of EPA Guidance Factors 

Factor 1: Air Quality Monitoring Data 

In general, Utah monitoring data are collected from Federal Reference Method (FRM) or Federal 

Equivalent Method (FEM) monitors that are sited and operated in accordance with 40 CFR Part 

58. The monitors are sited to address various monitoring objectives, including the assessment of 

air quality in regions where people live and work; the identification of highly impacted areas; 

and identification of background concentrations in areas of low impact. In addition, DAQ 

occasionally sites survey monitors for special purposes in areas where high ambient 

concentrations might be expected. As discussed earlier, ozone may be characterized as an 

“urban” pollutant; therefore, in most cases, these monitors have been sited in urban areas. The 

spatial distribution of these monitors may be seen in Figure 5. The colors of the dots used to 

approximate the monitor locations show whether the three-year average (2006-2008) of the 4th

highest ozone concentration at that monitor is at or below the current 0.075 ppm NAAQS 

(green) or above the NAAQS (red). The Santa Clara monitor was placed in operation in July 

2008 and does not yet have enough data history to be used for an official attainment 

determination. 
13

Figure 5. Utah’s Air Monitoring Network 

Attainment of the primary NAAQS for ozone is determined by the 4th highest concentration 

recorded at each monitor. Attainment of the ozone standard occurs when the most recent threeyear average of the 4th highest concentration recorded at each monitor is less than or equal to 

0.075 ppm. Conversely, nonattainment occurs when the most recent three-year average of the 4th

highest concentration recorded at each monitor is greater than 0.075 ppm. EPA recommends that 
14

States identify violating areas using the most recent three-year set of air quality data. In Utah, 

this encompasses the years from 2006 through 2008. Data affected by exceptional events may be 

excluded from use in identifying a violation if it meets the exclusion criteria. The three-year 

average data cited in this factor represents both flagged and unflagged data. Since the final 

designation determination by EPA is not required until March of 2010, data collected in 2009 

may be considered as the designation process proceeds. 

Table 1 shows the 4th highest ozone concentration as well as the three-year average of the 4th

highest ozone concentrations (design value) recorded at each of the monitoring stations in the 

DAQ network. These are the official monitors discussed previously in this section. An obvious 

conclusion from Table 1 is that there are several areas of nonattainment to the new 0.075 ppm 

standard within the monitoring network. These areas are located along the Wasatch Front in 

Weber, Davis and Salt Lake counties and are highlighted in red in Table 1. 

Table 1. Ozone Concentrations from official Utah DAQ Monitors 

1. Concentrations and counties indicated by red indicate violations of the current NAAQS. 

2. The Washington Terrace, West Valley and Herriman monitors were shut down in 2008 to make more efficient use of our resources. 

3. The Ogden monitor became operational on June 13, 2008. 

4. The Santa Clara monitor became operational on July 10, 2008. 

5. The left column indicates data with flagged days included. The right column indicates data with flagged days excluded. 

6. All monitors in the Provo-Orem MSA are attainment for ozone. 

Monitored concentrations in Utah County (North Provo, Highland and Spanish Fork), Box Elder 

County (Brigham City), Cache County (Logan), Tooele County (Tooele), and Washington 

County (Santa Clara) currently show attainment of the NAAQS. Monitors located in Box Elder, 

Tooele and Utah counties show that concentrations there are very close to exceeding the 

standard, and these areas will be discussed throughout this report. 

The Logan monitor in Cache County and the Santa Clara monitor in Washington County show 

that the monitored concentrations in these areas are well below the NAAQS; therefore Cache and 

Monitoring Sites 4th Highest O3 Concentration

Design Values

3-year Average of 

the 4th Highest O3

Concentration1 

Name County 2006 2007 20085 2006-20085 

Salt Lake-Ogden-Clearfield CSA 

Brigham City Box Elder 0.078 0.077 0.072/0.072 0.075/0.075 

Bountiful Davis 0.082 0.082 0.078/0.077 0.080/0.080 

Washington Terr2 Weber 0.083 0.080 No data n/a 

Ogden3 Weber no data no data 0.075 n/a 

Harrisville Weber 0.083 0.082 0.076/0.073 0.080/0.079 

Cottonwood Salt Lake 0.084 0.082 0.081/0.077 0.082/0.081 

Beach Salt Lake 0.082 0.082 0.074/0.073 0.079/0.079 

Hawthorne Salt Lake 0.082 0.079 0.076/0.072 0.079/0.077 

West Valley2 Salt Lake 0.080 0.080 no data n/a 

Herriman2 Salt Lake 0.082 0.079 no data n/a 

Tooele Tooele 0.079 0.076 0.071/0.070 0.075/0.075 

Provo-Orem MSA6 

North Provo Utah 0.074 0.075 0.075/0.073 0.074/0.074 

Highland Utah 0.077 0.078 0.072/0.071 0.075/0.075 

Spanish Fork Utah 0.079 0.077 0.071/0.070 0.075/0.075

Non-Wasatch Front Counties

Logan Cache 0.073 0.074 0.067 0.071 

Santa Clara4 Washington no data no data 0.063 n/a 
15

Washington counties will not be considered any further as potential areas for nonattainment 

designations. 

EPA has chosen to use NPS CASTNet monitoring data in their preliminary nonattainment 

decision making process. Data from national parks and monuments located within or in close 

proximity to the State of Utah are included in Table 2 to get a reasonable indication of ozone 

concentrations in remote areas of the State and Region. Again, it should be kept in mind that 

CASTNet monitors do not meet the same quality assurance standards as those maintained by the 

State of Utah and, as such, should be considered unofficial indicators. 

Table 2. Ozone Concentrations from National Park Service (CASTNet) Monitors and one 

monitor located in “Indian Country.” 

1. The Washakie monitor is located near Portage, Box Elder County, Utah, in “Indian Country”. This monitor is under the control of 

 the Northwestern Band of the Shoshone Nation. It is a Federal Reference Method monitoring site. 

Both DAQ and NPS monitors located in remote areas in and around the State of Utah indicate 

that rural areas of Utah are not violating the 0.075 ppm NAAQS. 

Factor 2: Emission Data 

Table 3 shows precursor component emissions for ozone in the counties under consideration for 

nonattainment designations. In the case of VOCs, biogenic emissions have been eliminated from 

consideration to get a clearer understanding of county industrial emissions. In addition, nonozone season emissions have also been deleted for each county to present a better picture of the 

actual ozone season precursors available during the summer ozone season. 

Table 3. Ozone Precursor Emissions (Utah 2005 Emission Inventory) 

Note: Non ozone season emissions including agricultural burning and harvesting, and all residential and wood combustion categories have been 

subtracted from total emissions to give a better picture of both VOC and NOx emissions during the ozone season. These emissions do not take 

place during the ozone season. 

Monitoring Sites 4th Highest O3 Concentration 3-year Average of the 4th

Highest O3 Concentration

Name Location 2006 2007 2008 2006-2008 

Washakie Res1 Northern UT 0.076 0.078 0.073 0.075 

Dinosaur NM Northeast UT no data 0.063 0.067 n/a 

Canyonlands NP Southeast UT 0.070 0.072 0.071 0.071 

Mesa Verde NP Southwest CO 0.074 0.070 0.069 0.071 

Zion NP Southwest UT 0.075 0.071 0.073 0.073 

Grand Canyon NP Northwest AZ 0.070 0.069 0.071 0.070 

Great Basin NP East Central NV 0.072 0.075 0.071 0.072 

Wasatch Front 

MSA 

Counties

VOC Emissions 

Not counting 

Biogenics 

(tpy) 

Ozone Season 

VOC 

Emissions 

(tpy)

NOx 

Emissions 

(tpy) 

Ozone Season 

NOx

Emissions 

(tpy) 

Box Elder 7,382 2,228 5,617 1,326 

Davis 11,635 6,994 10,741 2,627 

Morgan 613 276 3,170 789 

Salt Lake 37,121 24,069 38,106 9,779 

Summit 2,198 1,102 4,162 1,035 

Tooele 5,402 2,022 5,494 1,372 

Weber 8,346 5,332 6,880 1,663 

Wasatch 1,041 557 1,227 305 

Utah 17,315 10,891 13,591 3,473 

Juab 1,744 477 4,756 1,171 
16

Salt Lake, Davis and Weber Counties collectively produce 67.4 % of the VOCs and 59.8 % of 

the NOx that is monitored along the Wasatch Front. Utah and Juab Counties collectively have 

more moderate VOC and NOx emissions and account for 21.1 % of the VOC and 19.7 % of the 

NOx. Box Elder and Tooele Counties, which are located further from the central core of the 

Wasatch Front, have much lower VOC and NOx emissions, and together account for only 7.9 % 

of the VOC and 11.5 % of the NOx respectively. Morgan, Summit and Wasatch Counties, even 

though they are included in the Salt Lake-Ogden-Clearfield CSA, together only account for 

3.6 % of the VOC and 9.0 % of the NOx emissions during the ozone season. These percentages 

are depicted in the following pie charts. 

Percentage of VOC by County

21.1

7.9

3.6

67.4

Salt Lake, Davis & Weber Co's

Utah & Juab Co's

Box Elder & Tooele Co's

M organ, Summit & Wasatch Co's

Percentage of NOx by County

59.8 19.7

11.5

9.0

Salt Lake, Davis & Weber Co's

Utah & Juab Co's

Box Elder & Tooele Co's

M organ, Summit & Wasatch Co's

 Figure 6. Percentage of VOC and NOx produced along the Wasatch Front (by Counties)

In the case of both Box Elder and Tooele counties, the majority of VOC and NOx emissions are 

generated from sources that are located in the extreme eastern portions of these two counties; the 

western areas of both counties are very sparsely inhabited desert areas. Any VOC or NOx

produced in these west desert areas would come from sources located far from populated core 

areas (reference Figures 2 & 3). 

In Weber County, the majority of both VOC and NOx emissions are from sources located only in 

the western portion of the county. Western Weber County is part of the core nonattainment area 

of the Northern Wasatch Front because it is the home to several industrial sources that produce 

ozone precursors. The eastern portion of Weber County and all of Morgan County are located 

east of the Wasatch Range and, with the exception of the Devil’s Slide cement plant located in 

extreme eastern Morgan County, have only minor emissions of both VOC and NOx. The 

Wasatch Range prevents emissions from eastern Weber County and Morgan County from 

impacting in the core nonattainment area (see table 8). 

Summit County, located east of Salt Lake City, extends over 100 miles east from the Wasatch 

Range to the southern border of Wyoming. With the exception of one moderate point source, 

emissions of VOC and NOx in Summit County are very low. 

Juab County which is part of the Provo/Orem MSA extends from the Nevada border on the west 

to Mount Nebo, the southern most extension of the Wasatch Range, on the east. Like Tooele and 

Box Elder counties, it has little or no population west of the I-15 corridor which is located in the 
17

extreme eastern end of the county. The only significant industrial source of emissions in the 

county is the Leamington Cement Plant located in a mountainous area 35 miles west of Nephi. 

Cache County has relatively low VOC and NOx emissions during the ozone season. Washington 

County, located in the extreme southwest corner of Utah, has low to moderate VOC and NOx

emissions. 

In Section IX, Part D of the Utah State Implementation Plan which was submitted to EPA in 

January 2007, DAQ demonstrated that both VOC and NOx emissions along the Wasatch Front 

are projected to continue decreasing thorough at least 2014. This is demonstrated in the 

following VOC and NOx projection graphs (Figures 7 and 8) taken from the SIP: 

VOC Projections for Salt Lake & Davis Counties (tons/day)

Biogenic Source

Point Source

Area Source

Mobile On-Road

Mobile Non-Road

0

50

100

150

200

250

300

350

2002 2005 2008 2011 2014

VOC (tons/day)

Attainment = [308.06] 

Figure 7. VOC Projections through 2014

NOx Projections for Salt Lake & Davis Counties (tons/day)

Point Source

Area Source

Mobile On-Road

Mobile Non-Road

0

50

100

150

200

250

2002 2005 2008 2011 2014

NOx (tons/day)

Attainment = 233.39

Figure 8. NOx Projections through 2014 
18

Based on the relative emission levels presented in Table 3 and Figure 6, the majority of ozone 

precursor emissions along the Wasatch Front come from sources in the western portion of Weber 

County, Davis County and Salt Lake County. Utah County does produce a moderate amount of 

precursor emissions in the southern part of the county, but their effects are mainly felt only 

within Utah County due to the topography of Utah Valley. The remaining Wasatch Front 

counties, Box Elder, Juab, Morgan, Summit and Wasatch, have low or no impact on 

concentrations in the core area. 

Factor 3: Population Density 

Urbanization refers to a high concentration of population. It refers to populations that are 

directly attributable to or located within cities or large metropolitan areas. It is the opposite of 

rural, which refers to country areas with relatively low populations spread over larger areas. 

Directly associated with urbanization is the mix of human related emissions that can lead to 

elevated levels of ozone. EPA has made urbanized areas the focus of its guidance concerning 

violations of the ozone NAAQS, largely because precursor emission sources associated with 

both human and industrial activities occur with much greater frequency in these more populous 

areas. Table 4 below shows the population density in counties that are potential candidates for 

nonattainment areas. Population data from the most recent 2000 census has been plotted 

(persons/square kilometer) in Figure 9 for a large domain area extending from the Idaho border 

to central Utah. This is the area that includes the greater Wasatch Front, where approximately 85 

% of Utah’s population resides. 

Table 4. Population Densities in Counties being considered as potential candidates for 

Nonattainjment Areas

Note: Data obtained from State of Utah county census data 

When considering emissions of the precursors of ozone, population can be tied to emissions 

labeled as point source, area source, and mobile source emissions. It is fairly common for large 

point source industries to be co-located within or near large urban areas for many reasons, 

including access to human resources, educational institutions, transportation, distribution 

facilities, etc. Emissions from many of the area source categories are calculated on a per-capita 

County 

Initial State 

Recommendation

(Based on monitoring data) 2005 Population 

2005 Population 

Density 

( Population per square Km)

Salt Lake-Ogden-Clearfield CSA 

 Box Elder Attainment 45,142 18 

 Davis Nonattainment 276,374 1,098 

 Morgan Attainment 8,516 36 

 Salt Lake Nonattainment 970,748 3,082 

 Summit Attainment 36,283 41 

 Tooele Attainment 51,835 18 

 Wasatch Attainment 19,999 34 

 Weber Nonattainment 212,707 829 

Provo-Orem MSA 

 Utah Attainment 453,977 546 

 Juab Attainment 8,974 5 

Non-Wasatch Front MSA Counties 

 Cache Attainment 103564 202 

 Washington Attainment 117,385 124 
19

basis. In developing commonly used emission factors, it is recognized that population is a good 

surrogate for the number of minor industries that operate within any typical urban area. Mobile 

source emissions are also a function of the number of people who operate motor vehicles within 

a given area. This suggests that the bulk of the point source, area source, and mobile source 

emissions originate within regions with higher population densities which are shown in Figure 9. 

The risk of human exposure to unhealthy concentrations of ozone is greatest within densely 

populated areas. The distribution of the monitoring network attempts to address this by 

providing ozone monitoring in and around highly populated areas. This is illustrated by 

comparing Figures 5 and 9. As shown in Figure 9 the eastward extension of the population 

density essentially ends at the western border of the Wasatch Range. 

Figure 9. Population Density (Wasatch Front) with Counties 
20

There are several population centers located in the upper valleys east of the Wasatch Front, but 

these are mostly suburban farming communities with little or no industrial base. These areas will 

be addressed in the discussion of Factor 8 and in the “Additional Areas” section following the 

discussion of Factor 9. 

Thus far, the discussion has centered on northern Utah, which includes the Greater Wasatch 

Front. The Greater Wasatch Front is Utah’s most urbanized area, and is the only area to violate 

any of the prior NAAQS for ozone. Figures 2 and 3 show another area of the state, which may 

warrant some consideration on the basis of population and to some degree urbanization. The 

populous region in the southwest corner of the State is the city of St. George which has a 

population of sixty-five thousand (there are about one-hundred twenty thousand people in the 

greater St. George area). Consideration of this region would be in the context of its own 

nonattainment area, rather than as one which contributes to a violation elsewhere. As some of 

the remaining factors to be considered are discussed, Utah’s recommendation concerning 

Washington County will be discussed further. 

Factor 4. Traffic and Commuting Patterns 

Data presented in Table 5 displays vehicle miles traveled, the number of commuters driving, in 

county and out-of-county, and the percentage of commuters that commute to other counties to 

work, in areas being considered for nonattainment designations. 

Salt Lake County is the destination for the largest number of out-of-county commuters from 

Davis, Tooele and Utah counties. Conversely, Davis and Utah counties are the destinations for 

the largest number of out-of-county commuters from Salt Lake County. Most out-of-county 

commuters from Box Elder County commute to Weber County for work and most out-of-county 

commuters from Morgan and Weber County commute to Davis County for work. Similarly 

most out-of-county commuters from Tooele, Summit and Wasatch counties commute to Salt 

Table 5. Traffic and Commuting Patterns (2005 Data)

Note: Data obtained from www.epa.gov/ttn/naaqs/pm/pm25_2006_techinfo.html. (VMT by county, County-to County worker flows) 

County 

Initial State 

Recommendation 

(Based on Monitoring 

Data) 

2005 VMT 

(Millions/Year) 

Commuting

Within 

County 

(number)

Commuting 

to other 

Counties 

(number)

Commuting 

to other 

Counties 

(% of total) 

Salt Lake-Ogden-Clearfield CSA 

 Box Elder Attainment 782.7 13,570 4,330 24.2 

 Davis Nonattainment 3,352.0 61,208 50,567 45.2 

 Morgan Attainment 109.2 1,217 1,930 61.3 

 Salt Lake Nonattainment 7,511.9 411,283 24,189 5.6 

 Summit Attainment 551.4 10,486 4,912 31.9 

 Tooele Attainment 804.2 9,784 7,655 43.8 

 Wasatch Attainment 226.8 3,857 2,968 43.5 

 Weber Nonattainment 1,994.6 64,671 25,975 28.7 

Provo-Orem MSA 

 Utah Attainment 4,214.8 140,843 21,050 13.0 

 Juab Attainment 342.9 2,011 1,332 39.8 

Non-Wastach Front MSA Counties 

 Cache Attainment 935.9 39,235 3,987 9.2 

 Washington Attainment 1,112.8 32,708 977 2.9 
21

Lake County to work. Most out-of-county commuters from Juab County work in Utah County. 

Essentially most of the out-of-county commuters travel into the core metropolitan areas to work 

and return commute to their home counties after work. 

This is evidenced by the fact that several of the counties that are candidates for nonattainment 

show a higher percentage of commuters traveling to Salt Lake County than those traveling from 

Salt Lake County to other counties. 

In addition, from table 5 it is obvious that commuting trips from counties that make up the 

periphery of the Wasatch Front core area (Box Elder, Morgan, Summit, Tooele, and Wasatch) 

are insignificant when compared to the number of in-county trips within the core counties 

(Davis, Salt Lake, and Weber). 

Hill Air Force Base, located in northern Davis County, is one of the largest employers in the 

state. It employs people from all counties located along the Wasatch Front. On the other hand, 

the vast majority of employees at Brigham Young University, another large employer in the 

state, commute mainly from within Utah County. 

Mobile sources have always been a significant source category in the attribution of NOx which is 

one of the precursor gasses needed to form ozone. Without current federal requirements that 

mandate improvements in NOx emissions from cars and light-duty trucks, it is unlikely that the 

previous (0.08 ppm) ozone standard could have been attained along the Wasatch Front. Mobile 

sources currently account for approximately 65% of the NOx within the areas likely to be 

designated nonattainment for ozone. The two largest Metropolitan Planning Organizations 

(MPOs) for the Wasatch Front have provided detailed emissions data for use in modeling 

exercises. Most significant is the information concerning vehicle miles traveled (VMT). This 

information has been geographically compiled on the basis of travel along what are called 

roadway “links” for a study area surrounding the Wasatch Front. These links describe discrete 

portions of the transportation network that are categorized as either freeways or arterial 

roadways. When this information is plotted on a map (see Figure 10), the result is a very good 

approximation of Utah’s urban population distribution. 
22

Figure 10. Population Density and Area Roadways

Factor 5. Growth Rates and Patterns 

This factor looks at actual population and VMT growth from 2000 to 2005 as well as forecasted 

population and VMT growth to 2020. Generally, counties with rapid or higher than average 

population and VMT growth are found to be integral parts of an urban core area. Tables 6 and 7 

show the most recent population and VMT projections for counties that could be considered for a 

nonattainment designation. The tables are based on actual 2000 and 2005 census and VMT data 

with projections to 2010 and 2020. Table 6 shows that both Salt Lake and Utah counties are 

expected to have the highest population growth of all counties located along the Wasatch Front 
23

over the next twelve years. Utah County’s anticipated population growth rate from 2010-2020 

is, in fact, one and one-half times that of Salt Lake County’s. This expected growth correlates 

quite well with the current location of Utah’s major industrial and educational infrastructure. 

Davis County, which borders Salt Lake County on the north, is expected to have the next highest 

population growth with Weber County close behind. These four counties, which make up the 

core emissions area of the Wasatch Front, will account for approximately 82.5 percent of the 

Wasatch Front population growth by 2020. Tooele, Box Elder and Juab counties, located on the 

northern and western periphery of the major core areas, and Morgan, Summit and Wasatch 

counties, located east of the Wasatch Range, will also experience significant increases in their 

population numbers, but will only account for 17.5 percent of the core area population growth by 

2020. 

When considering Metropolitan Planning Organizations (MPOs), The Wasatch Front MPO, 

consisting of Salt Lake, Davis, Weber, Morgan and Tooele counties, is expected to have a 

Table 6. Projected Population Growth (2000-2020) 

 Note: Data obtained from www.governor.utah.gov/dea/projections.html (Governor’s Office of Planning and Budget – GOPB). 

population increase of over 300,000 between 2010 and 2020. The Mountainland Association of 

Governments (MAG), consisting of Utah, Summit and Wasatch counties, is expected to have a 

population growth of over 165,000 during the same time period. These increases translate to an 

18.1 percent increase for the Wasatch Front MPO and a 27.8 percent increase for the 

Mountainland MPO. 

As we look at Table 7 below, it should be noted that there are many similarities between 

population growth and VMT growth. With the exception of Box Elder County that experienced 

an actual decrease in VMT between 2000 and 2005, all counties in the area are projected to have 

significant population and VMT growth through 2020. 

Area 2000 

Actual 

2005 

Actual 

Actual 

Increase 

2000-2005 

2010 

Estimated

Estimated 

Increase 

2005-2010

2020 

Estimated 

Estimated 

Increase 

2010-2020

Salt Lake-Ogden-Clearfield CSACounties 

Box Elder 42,860 45,142 2,282 49,254 4,112 61,675 12,421 

Davis 240,204 276,374 36,170 304,502 28,128 352,320 47,718 

Morgan 7,181 8,516 1,335 10,589 2,073 16,756 6,167 

Salt Lake 902,777 970,748 67,971 1,053,258 85,510 1,230,817 177,559 

Summit 30,048 36,417 6,369 44,511 8,094 65,001 20,490 

Tooele 41,549 51,835 10,293 67,150 15,315 95,696 28,546 

Wasatch 15,433 20,138 4,705 25,516 5,378 37,082 11,566 

Weber 197,541 212,707 15,133 230,145 17,438 271,339 41,194 

Provo-Orem MSA 

Juab 8,310 8,974 664 10,519 1,545 14,158 3,639 

Utah 371,894 453,977 82,083 527,502 73,525 651,319 123,817 

Non-Wasatch Front MSA Counties 

Cache 91,897 102,477 10,580 114,304 11,827 147,776 33,472 

Washington 91,104 125,010 33,906 162,544 37,534 251,896 99,352 

Areas/MPO’s 

Bear River 136,712 149,705 12,993 165,705 16,000 211,898 46,193 

Wasatch Front 1,389,252 1,520,189 130,973 1,665,238 145,049 1,966,372 301,134 

Mountainland 417,375 510,532 93,157 597,529 86,997 763,402 165,873 

Southwest 135,969 176,202 40,233 223,846 47,644 335,025 111,179 

State of Utah 2,246,553 2,528,926 282,373 2,833,337 304,411 3,486,218 652,881 
24

Table 7. Projected Annual VMT Growth in Greater Wasatch Front Area (Millions)

Note: Data obtained from Wasatch Front Regional Council, Mountainland Association of Governments, Utah Dept of Transportation, and 

Governors Office for Planning and Budget-GOPB. 

Similar to Table 6 for population growth, Table 7 shows that, over the next twelve years, Salt 

Lake and Utah counties are expected to have the highest VMT growth of all the counties along 

the Wasatch Front area. From the data we can calculate that, from 2010-2020, Weber, Davis, 

Salt Lake, and Utah County’s expected VMT growth rates will be 33.8 %, 22.4 %, 22.8 % and 

26.1 % respectively. Once again, and with numbers similar to those for population growth, these 

four counties will account for 74 percent of the areas VMT growth by the year 2020. 

Factor 6. Meteorology 

The quality of Utah’s air is generally good, with the exception of certain episodic periods during 

which the air quality is degraded. In the case of ozone, these episodes are most always 

associated with a semi-permanent high pressure ridge that becomes stationary over the 

intermountain region, clear skies, intense direct sunlight, and stagnant air with very light surface 

wind movement. When these meteorological conditions occur simultaneously, they can aid in 

the formation of ozone while at the same time providing minimal vertical mixing. 

Under these stagnant conditions, emissions produced within the populated urban valley areas do 

not disperse and are maintained in the bowl-shaped valleys. As a result, increased concentrations 

of ozone are able to build up over a period of several days and to actually meander or oscillate 

north/south along the Wasatch Front. Under proper conditions, air originating in a southern area 

could move northward along the Wasatch Front, and conversely, air originating in a northern 

area could travel southward along the same path. 

 

Actual day-to-day transport of the ozone along the Wasatch Front is mainly influenced by the 

diurnal effects of the local mountain/valley airflow caused by the Great Salt Lake and Utah Lake on 

the west and the very prominent Wasatch Range on the east (see table 8). As mentioned above, 

areas of high ozone concentration have been shown to oscillate both north and south along the 

Wasatch Front. They also move east and west from areas adjacent to the Wasatch Front to areas over 

the Great Salt Lake in Weber, Davis and Salt Lake Counties and over Utah Lake in Utah County. In 

County 2000 

Actual 

2005 

Actual 

Actual 

VMT

 Increase 

2000-2005 

2010 

Estimated

Estimated 

VMT

Increase 

2005-2010 

2020 

Estimated 

Estimated 

VMT 

Increase 

2010-2020 

Salt Lake-Ogden-Clearfield CSA 

Box Elder 2.96 2.92 (.040) 3.55 0.63 4.85 1.30 

Davis 5.72 6.21 0.49 7.19 0.98 8.80 1.61 

Morgan 0.38 0.38 0 0.46 0.08 0.63 0.17 

Salt Lake 21.63 23.36 1.73 27.27 3.91 33.49 6.22 

Summit 2.12 2.03 (0.09) 2.46 0.43 3.37 0.91 

Tooele 1.82 2.37 0.55 2.88 0.51 3.95 1.07 

Wasatch .64 .82 0.18 1.00 0.18 1.37 0.37 

Weber 3.98 4.31 0.33 4.56 0.25 6.10 1.54 

Provo-Orem MSA 

Juab 1.04 1.17 0.13 1.42 0.25 1.95 0.53 

Utah 8.62 10.01 1.39 11.48 1.47 14.48 3.00 
25

all cases the general westward movement occurs during the late evening and nighttime hours and the 

reverse eastward movement occurs during the daylight hours. This is a typical mountain valley 

flow. 

In the case of Box Elder County in the north and Tooele County in the south, it is possible that 

the diurnal air flow moves air containing “ozone clouds” into and out of these counties on a 

routine basis and could be responsible for some of the higher concentrations monitored in these 

counties. In essence, both Box Elder and Tooele Counties are not significant emitters of ozone 

or its precursors, but receptors. The same could be said for all counties east of the Wasatch range 

and for Juab County south of the Wasatch Front. 

Factor 7. Geography/Topography 

The Wasatch Range, extending from near the Idaho border to Mt. Nebo, at the southern tip of the 

Northern Rocky Mountains, is a formidable obstacle to surface air mass movement toward the 

east. A satellite view of the region is provided in Figure 11. Probably the most prominent 

feature in this figure is the Wasatch Front which functions as the eastern boundary of the Great 

Basin. Here, the Wasatch Mountains rise abruptly to elevations of between 4,000 to 6,000 feet 

above the valley floor and help to define the Wasatch Front urban areas from Brigham City on 

the north to the numerous metropolitan areas in Utah County on the south. These valleys are 

bound on the West by the Great Salt Lake in the north and the Oquirrh Mountains, which also 

rise 4,000 to 5,000 feet above the valley floor, in the south. In an area of flat terrain one would 

expect an air mass to gradually be transported in a direction consistent with the prevailing air 

flow. Conversely, in an area of mountainous terrain, as is the case of the valleys along the 

Wasatch Front, one would expect the terrain to define the air mass boundaries and movement. 

With prevailing winds from the west through the north, the high terrain with its bowl shaped 

valleys that open to the north and west routinely functions to block any eastward horizontal 

movement of a stagnant air mass. In effect, the local topography actually contains stagnant air 

masses within these valleys. 

 

To help appreciate the significance of the barrier that the Wasatch Front Range poses to the 

eastward horizontal movement of air, Table 8 gives the average valley floor elevation at several 

sites along the Wasatch Front and the average elevation of the Wasatch Mountain Range directly 

east of the valley floor location. 

 
26

Figure 11. Wasatch Front Topography 
27

Table 8. Elevations of Valley Floor and Adjacent Mountains along the Wasatch Front

 

As discussed in the meteorology section, it has been found in several studies that concentrations 

of ozone trapped in large mountain valleys along the Wasatch Front, such as the Salt Lake 

Valley and Utah Valley, actually move horizontally within or in and out of the valleys with the 

diurnal mountain-valley flow. In the Salt Lake Valley, for instance, the nighttime flow generally 

moves the air to the northwest over the eastern portion of the Great Salt Lake while the daytime 

flow moves the same air back southeastward into the valley where it is contained by the Wasatch 

Range. In Utah Valley the air is more contained and generally moves westward over Utah Lake 

in the evening and eastward again during the day. In some instances, however, the air mass in 

either the Salt Lake Valley or Utah Valley has moved north or south to affect the other valley. In 

the region north of Salt Lake City air masses have a tendency to move both north and south 

along the Wasatch Front as well as east and west with the diurnal flow. 

Not only does the topography of these regions act as a barrier to air movement during conditions 

which lead to elevated concentrations of ozone, it also acts as the primary factor in determining 

where the population is located. In other words, the lower valleys which contain the air during 

periods of summertime stagnation are also the areas within which most people choose to live. 

These populations produce the emissions which lead to ozone formation under the conditions 

described above. 

Both Figure 11 and Table 8 show that much of the eastern area of the Wasatch Front counties is 

at a much higher elevation than the adjacent western valleys, and would therefore not experience 

the high concentrations of ozone produced in these urban valleys. These regions would have 

neither the sources of emissions necessary to produce high ozone concentrations, nor a pathway 

for incurring impact from upwind urban areas. 

Thus, the topography, when considered alongside the predominant meteorology, would suggest 

that these areas of high mountainous terrain not be included in a description of nonattainment 

area(s). 

Box Elder County Valley Elevation Mountain Elevation Elevation difference

 Tremonton 4320 ft 8979 ft 4659 ft 

 Honeyville 4291 ft 9330 ft 5039 ft 

 Brigham City 4363 ft 8035 ft 3672 ft 

Weber County 

 Harrisville 4390 ft 9196 ft 4786 ft 

 Ogden 4350 ft 9238 ft 4888 ft 

Davis County 

 Kaysville 4363 ft 9297 ft 4934 ft 

 Bountiful 4283 ft 8819 ft 4536 ft 

Salt Lake County 

 Salt Lake City 4363 ft 9107 ft 4744 ft 

 Cottonwood 4455 ft 9176 ft 4721 ft 

Utah County 

 Highland 4950 ft 10,698 ft 5748 ft 

 Provo 4691 ft 10,630 ft 5939 ft 

 Spanish Fork 4590 ft 9430 ft 4840 ft 

Average 4451 ft 9328 ft 4876 ft 
28

Factor 8. Jurisdictional Boundaries 

In this factor we will look at jurisdictional boundaries and regional government organizations 

that have law-making authority for these areas. When considering these organizations, and their 

areas of jurisdiction, it will become clear that the implementation of most of the required control 

strategies necessary to combat precursors to ozone could be best implemented on a county basis. 

Box Elder County 

Box Elder is a very large and mostly rural county located in the northwest corner of Utah. 

Ninety-nine plus percent of the population is concentrated in the extreme eastern portion of the 

county along the northern Wasatch Front and closely associated with the I-15 and I-84 freeways 

that extend north into Idaho. The western three-quarters of the county, extending to the Nevada 

border, is made up of a few unincorporated towns with populations ranging from zero to 20; 

mostly early railroad towns originally founded in the 1800’s. This area would be described as 

extremely rural and very remote. The eastern area of the county could be considered as the 

northern most extension of the Ogden/Salt Lake/Provo megalopolis, even though it is separated 

from the Ogden Valley by 10 - 15 miles of open farmland and a moderately large recreation area 

(Willard Bay). The entire population of Box Elder County amounts to less than 2 percent of the 

population found along the Wasatch Front. 

The only monitored exceedances of the 0.075 ppm ozone standard in this county occurred at 

Brigham City which is located near the eastern edge of the county at the foot of the Wasatch 

Range. Most of the sources of VOC and NOx can be traced to area and mobile sources 

associated with urbanization along the I-15/I-84 corridor. Box Elder County does have industrial 

sources that produce ozone precursors, but these sources are currently not large enough to make 

Box Elder County a source area of ozone. Generally, whenever the monitor at Brigham City has 

recorded an exceedance of the NAAQS, the increased concentrations at the monitor have been 

traced to areas located further south that are part of the major Wasatch Front core area. In these 

cases, a southerly wind flow carried the ozone plume north along the Wasatch Front as there is 

no substantial geography or topography separating this core area to the south from Brigham City. 

Under the previous 8-hour ozone standard Box Elder County was designated as “attainment” for 

ozone. Under the current 8-hour ozone standard (0.075 ppm), Box Elder County is still 

maintaining attainment level concentrations (2006 – 2008). Based mainly on this current 

monitoring data, Utah will recommend that Box Elder County be designated “attainment” for 

ozone. If future monitoring data (2007 – 2009) at the Brigham City monitor indicates that the 

area is not in attainment, then Utah would recommend that Box Elder County be designated 

nonattainment only for the townships east of the I-15/I-84 junction. The remainder of the 

county, extending west to the Nevada border, would be recommended for a designation of 

“attainment/unclassifiable.” However, Box Elder County is within the modeling domain, and all 

emissions from this county will be included in the modeling used to develop the SIP for ozone. 

Any source in Box Elder County found to have a significant impact on the nonattainment area 

will be controlled as if it were in the nonattainment area. 

 

Weber County 

Much the same argument could be made for Weber County, in which all of the areas surrounding 

the selected townships are either located in high terrain or are part of the Great Salt Lake. There 
29

is, however, one notable exception; and that is the town of Huntsville, located east of the 

Wasatch Front in a high mountain valley. There is no reason to suspect that Huntsville, which 

has no industrial base, except for three ski resorts and a recreation reservoir, is not attaining the 

ozone standard, yet there is enough of a population to warrant a careful consideration of 

sweeping regulations that need not necessarily apply. Under the previous 8-hour ozone standard, 

all of Weber County was designated as an ozone maintenance area. Utah will recommend that 

all of Weber County, west of the ridgeline tracing the Wasatch Mountains, be designated 

“nonattainment” for ozone, with the remainder of the county, east of the Wasatch ridgeline, 

being recommended for a designation of “attainment/unclassifiable.” 

Morgan County 

Morgan County is located east of Davis County. It is separated from the metropolitan core areas 

of the Wasatch Front by the Wasatch Range. The town of Morgan surrounded by eight smaller 

towns and several family farms comprises the center of population in this very rural county. The 

only industry in the county, the Devil’s Slide cement plant, is located eight miles east of Morgan 

in a mountainous area near the border with Summit County. Ozone formation has never been a 

concern in Morgan County mostly because of its rural setting, lack of ozone precursors and 

significant topographical separation from the Wasatch Front. Utah will recommend that Morgan 

County be designated “attainment/unclassifiable.” However, Weber County is within the 

modeling domain, and all emissions from this county will be included in the modeling used to 

develop the SIP for ozone. Any source in Morgan County found to have a significant impact on 

the nonattainment area will be controlled as if it were in the nonattainment area. 

Davis County 

The only portions of Davis County not covered by the selected townships are over the Great Salt 

Lake. Under the previous 8-hour ozone standard, all of Davis County was designated as an 

ozone maintenance area. Utah will recommend that all of Davis County be designated 

“nonattainment” for ozone. 

Salt Lake County 

The collection of townships used to define the non-attaining portions of Salt Lake County 

includes all but the mountainous terrain in the very western edge and approximately the eastern 

third of the county which is occupied by the Wasatch Range. There is some population present 

within the various canyons of this eastern range. In this case, DAQ feels it would be appropriate 

to include these areas for the sake of vehicle I/M and other regulatory programs. Under the 

previous 8-hour ozone standard, all of Salt Lake County was designated as an ozone 

maintenance area. Utah will recommend that all of Salt Lake County be designated 

“nonattainment” for ozone. 

Summit County 

Summit County is located directly east of Salt Lake City. It is separated from the Wasatch Front 

core area by a distance of between eight and ten miles and the very substantial Wasatch Front 

Range. As discussed earlier, Summit County extends eastward from the back of the Wasatch 

Range to the western and southern Wyoming border. Most of the population is located in the 

Park City area and the predominant industry there is tourism. There is one moderate point 
30

source located in Summit County, a shale processing plant, about ten miles from Park City in a 

very sparsely populated mountainous area. Further discussion of Summit County and the Park 

City area will be made in the “Consideration of Additional Areas” section following factor 9. 

Utah will recommend that Summit County be designated “attainment/unclassifiable.” However, 

Summit County is within the modeling domain, and all emissions from this county will be 

included in the modeling used to develop the SIP for ozone. Any source in Summit County 

found to have a significant impact on the nonattainment area will be controlled as if it were in the 

nonattainment area. 

Utah County 

Utah County is located directly south of the Salt Lake-Davis-Weber nonattainment core area. 

Current monitoring data (2006 – 2008) from the three DAQ monitors located in Utah County 

(see Table 3) show that all monitors are at or below the attainment level. Decreasing ozone 

concentration trends at these monitors show that the decreasing VOC and NOx trends discussed 

in factor 2 are slowing ozone formation in Utah County. Based on the most recent monitoring 

data, Utah will recommend that Utah County be designated as “attainment.” However, Utah 

County is within the modeling domain, and all emissions from this county will be included in the 

modeling used to develop the SIP for ozone. Any source in Utah County found to have a 

significant impact on the nonattainment area will be controlled as if it were in the nonattainment 

area. 

If future monitoring data (2007 – 2009) at any of the Utah County monitors indicate that the area 

is not in attainment, then Utah would recommend that Utah County be designated 

“nonattainment” only for the townships west of the ridgeline tracing the Wasatch Mountain 

Range. The remainder of the county, extending east to Wasatch County would be recommended 

for a designation of “attainment/unclassifiable.” 

Wasatch County 

Heber Valley, the main populated area of Wasatch County, is situated approximately fifteen 

miles northeast of Provo, Utah. It is a relatively high mountain valley whose main industry is 

farming and recreation. It is known for its crystal clear air and breathtaking views. In recent 

years the population has seen an increased of retirees from California settle in the valley because 

of its pristine climate. There are no threatening point sources located in Wasatch County and for 

this reason Utah will recommend that Wasatch County be designated 

“attainment/unclassifiable.” However, Wasatch County is within the modeling domain, and all 

emissions from this county will be included in the modeling used to develop the SIP for ozone. 

Any source in Wasatch County found to have a significant impact on the nonattainment area will 

be controlled as if it were in the nonattainment area. 

Tooele County 

Tooele County, like Box Elder County to the north, is a very large county with a significant 

population and business presence located primarily south of US Interstate 80 and east of the 

Stansbury Mountain Range. Southwest of this range and extending to the Nevada border is the 

Utah Military Test Range and the Army’s Dugway Proving Grounds with a permanent 

population of zero. 
31

Under the previous 8-hour ozone standard, all of Tooele County was designated as “attainment” 

for ozone. Under the current 8-hour ozone standard (0.075 ppm), Tooele County is still 

maintaining (2006 – 2008) attainment level concentrations. Based mainly on current monitoring 

data, Utah will recommend that Tooele County be designated “attainment” for ozone. 

If future monitoring data (2007 – 2009) at the Tooele monitor indicates that the area is not in 

attainment, then Utah would recommend that Tooele County be designated nonattainment only 

for the townships east of the Stansbury Mountain Range. The remainder of the county, 

extending west to the Nevada border, would be recommended for a designation of 

“attainment/unclassifiable.” However, Tooele County is within the modeling domain, and all 

emissions from this county will be included in the modeling used to develop the SIP for ozone. 

Any source in Tooele County found to have a significant impact on the nonattainment area will 

be controlled as if it were in the nonattainment area. 

Juab County 

Juab County is located south of Tooele County and southwest of Utah County. It extends from 

the Nevada border on the west to the Wasatch Range on the east, an east-west distance of over 

100 miles. The only sizeable population, with the exception of less that 100 members of the 

Goshute tribe located on their tribal land in the extreme northwest corner of county, is located in 

the far eastern end of the county. The main industry is turkey farming and livestock on several 

large ranches near the eastern end of the county. There is one relatively small point source, the 

Leamington cement plant, located about twenty-five miles west of Nephi near the Millard 

County border. The air quality in Juab County is seldom influenced by air from neighboring 

Utah County due to the elevated ridge that makes up their common border. Utah will 

recommend that Juab County be designated “attainment/unclassifiable.” However, Juab County 

is within the modeling domain, and all emissions from this county will be included in the 

modeling used to develop the SIP for ozone. Any source in Juab County found to have a 

significant impact on the nonattainment area will be controlled as if it were in the nonattainment 

area; modeling will also include the Intermountain Power Plant located just south of Juab County 

in Millard County. 

Washington County 

Washington County is located in the very southwest corner of Utah. Currently data from the 

Santa Clara monitor and the Zion National Park CASTNet monitor show ozone concentrations to 

be well below the current standard. In 2005 the CASTNet monitor at the Zion National Park site 

recorded high ozone concentrations over a period of several days, but these higher recorded 

concentrations were directly attributable to wildfires that were located in the immediate vicinity 

of the monitor. It should also be noted again that CASTNet monitors do not meet the more 

stringent FRM or FEM requirements specified in 40 CFR Part 58. 

As the St. George area grows in both population and VMT, it is conceivable that the area could 

one day exceed the ozone standard. At this time, however, Utah will recommend that 

Washington County be designated attainment for ozone. 
32

Factor 9. Level of Control of Emission Sources 

This factor will discuss the emission controls that are currently implemented for the major 

precursors of ozone, namely VOC and NOx in the areas under consideration. 

The control of emissions is governed by the State’s Air Quality Rules which can be found at 

http://www.rules.utah.gov/publicat/code/r307/r307.htm. These rules include emission 

inventories, control measures, and permitting and compliance limits. Emission controls and 

permit limits have been established to meet federal requirements and, as necessary, to meet 

applicable NAAQS. 

As discussed previously, in areas where meteorological conditions are conducive to ozone 

episodes and the air becomes stagnant for several days at a time, it is likely that sources of VOC 

and NOx would coincide (in location) with areas monitoring high ozone concentrations. We 

have already noted the coincidence of population, low-land valley regions, and transportation 

networks with a network of air monitors indicating violations of the 8-hour NAAQS for ozone. 

That the emission sources would also be located in these areas comes as no surprise. 

Nevertheless, this is one of the factors that must be evaluated in order to determine not only the 

core area(s) of nonattainment, but also those areas which may be contributing to violations 

within these nonattainment area(s). 

Any inventory prepared by DAQ typically includes three categories of sources: large industrial 

point sources, area sources, and mobile sources. While the first and the last of these categories 

are more or less self explanatory, area sources are generally those of an industrial nature that are 

too small and too numerous within an urbanized area to inventory on an individual basis. 

Instead, they are categorized, and emission factors are developed which relate these activities 

and their associated emissions back to population. 

The emissions data used for this analysis is the same data that was reported to EPA and 

subsequently entered into the NEI database. It represents annual data from 2005, with some 

minor adjustments made to put mobile source emissions on the same basis (mobile source 

emissions are typically calculated in terms of tons per day). For each of these three categories, 

VOC and NOx emissions were evaluated. These gasses are known precursors to the formation of 

ozone and generally must be evaluated for emission reductions in nonattainment areas. 

 

The focus area was on the area surrounding northern Utah. This area is often evaluated in 

rigorous computer modeling exercises by DAQ, which enables the use of one such exercise 

which includes a “gridded” emissions inventory within a modeling domain that includes the 

entire Wasatch Front and surrounding areas. In other words, within the area of the domain 

shown in Figure 11, the emissions have been located in grid cells measuring one square 

kilometer each. This lends a high degree of accuracy to the analysis. 

As discussed earlier, in the section on traffic and commuting patterns, mobile source emissions 

are well represented by the distribution of population. Area sources also show good correlation 

with the location of population. As discussed before, many of the emission factors used to 

estimate emissions from area source categories are related to population. Good examples of this 

would include fuel distribution or emissions related to industry. There are, however, other 
33

source categories for which population is not a good surrogate. Included in this group would be 

emissions related to agriculture, such as agricultural burning, harvesting and land preparation. A 

complete tabulation of the 2005 emissions inventory for Utah has been included as Appendix 1 

to this document. 

Figure 12 shows the location of these emissions relative to the core set of nonattainment 

townships. It is apparent that the coincidence of the two is very good, and for the reasons 

discussed above, this is to be expected. In the figure, point sources are identified by green circles 

where size of the circle is indicative of the quantity of emissions produced by the source. The 

cut-point for inclusion as a point source was 100 tons/yr of combined NOx and VOC. Smaller 

sources were simply included as area sources. The collection of point sources, along with the 

higher concentrations of area and mobile emissions, shows what might be considered a core 

urban area or areas within the proposed Wasatch Front nonattainment region. This is consistent 

with the EPA’s definition of what the agency believed would characterize a typical urban 

nonattainment area. 

The addition of the emissions information serves to reinforce the notion of a core collection of 

townships that will be included in the nonattainment area recommendations. These townships 

are representative of air quality data that indicates concentrations in excess of the 8-hour 

NAAQS for ozone. To a large extent, these townships are bounded by elevated terrain which 

acts to define low-land valleys within which summer air can become stagnant long enough for 

concentrations to become elevated. These townships also describe a region within which most of 

the population resides, and therefore a region from which most of the emissions that contribute to 

ozone originate. 

It is apparent from Figure 12 that there are other areas of emissions located outside of the major 

core area. Those areas will be discussed in the next section. DAQ requires BACT on all major 

sources in compliance with federal law, and on all minor sources through our state only 

regulatory program. Any source found to have a significant impact on a nonattainment area will 

be controlled as if it were in the nonattainment area. 

 
34

Figure 12. Emissions in Relation to Core Nonattainment Areas

An indication of the point sources located in the CSA/MSAs is annotated in Figure 12 and a 

complete tabulation of their respective emissions is included as Appendix 2 to this document. 
35

Consideration of Additional Areas Outside the Wasatch Front Core 

Area 

In order to fully consider the smaller areas of emissions located outside the major core area, each 

of these smaller areas will now be discussed with regard to factors pertinent to each respective 

area. The most important of these factors will be air quality data and topography. Traffic and 

commuting patterns and projected growth will also be considered in the context of bedroom 

communities which may or may not impact the core nonattainment area. 

In Figure 12, four areas have been identified; Park City and Heber Valley which lie to the east of 

the Wasatch Front, and Brigham City and the Tooele Valley which lie west of the Wasatch 

Front. In addition, there are two other areas of the State not included in the northern Utah 

“domain.” These are the greater St. George area of Washington County located in the southwest 

corner of Utah and San Juan County located in the southeast corner of Utah. 

Park City, Summit County 

Park City lies to the east of the Wasatch Mountains in a relatively high elevation valley (~6,500 

ft.) called the Snyderville Basin. Park City itself is listed at an elevation of just over 7,000 feet. 

It was originally settled as a silver mining town in the 1870’s and was home to the Silver King 

Mine, the worlds richest silver mine. Park City is primarily a resort and bedroom community 

with significant commuter travel to and from the Salt Lake Valley. The Snyderville Basin is 

surrounded by high terrain to the west, south and southeast. July is the hottest month of the year 

but rarely, due to its elevation, does the temperature rise above 80 degrees Fahrenheit. There are 

very few sources of ozone precursors in the area and, regular diurnal flow, in most instances, 

keeps the area crystal clear. The most significant aspect of the geography of the area is the lack 

of a connection to the Salt Lake Valley to the west. The elevation of the pass (Parley’s Summit) 

connecting the Salt Lake Valley to the Snyderville Basin is 7,100 feet. This in essence does not 

allow any significant surface air movement between the two valleys. For these reasons, ozone 

formation is unlikely. 

Park City, Utah looking southwest toward the Salt Lake Valley 
36

Park City has a relatively small permanent population that is enhanced in the winter season by 

large numbers of skiers. There is no data to indicate that the air quality in Park City exceeds the 

NAAQS for ozone. 

The only reason to possibly conclude that Park City contributes to violations in the Salt Lake 

Valley would be the level of vehicular traffic between the two areas. While it is true that Park 

City is considered somewhat of a bedroom community to Salt Lake, the only implication for the 

Salt Lake nonattainment area would be an influx of vehicles that are not required to meet the 

same level of Inspection/Maintenance as those registered along the Wasatch Front. Were Park 

City to be designated as nonattainment, it could implement an I/M program. Without a detailed 

analysis of Park City and its fleet of vehicles, it is not possible to quantify the benefit such a 

program might provide. However, a significant portion of these vehicles includes some degree 

of onboard diagnostic (OBD) equipment, and, therefore, the influx of vehicles into the Wasatch 

Front would not be characterized as an older fleet that would benefit greatly from an I/M 

program. 

Control of emissions at point sources would also not be an issue in this case. It is evident from 

Figure 12 that there are no major point sources in Park City that could be affecting the Wasatch 

Front. Even if there were, it would be highly unlikely that a significant degree of improvement 

in emissions control would be achievable only through the SIP process. Utah’s permitting rules 

already require Best Available Control technology on all sources, major or minor, constructed 

after 1971. 

Growth estimates for the Park City area may be surmised from the countywide estimates 

provided by the Governor’s Office of Planning and Budget. Park City is really the only 

populous region of Summit County, so it may be assumed that almost all of the countywide 

growth will take place in and around Park City. Table 6, located in the Factor 5 discussion, 

summarizes the projected population growth in the areas of interest to this analysis. Relative to 

the 2000 census, growth in Summit County is occurring at a rate of four to five percent per year. 

This is roughly twice the average for the entire state, which is projected to be about two and a 

half percent per year. As a reference point, population growth for the State of Utah during this 

same period is approximately 2.5 percent while that of the United States during this same period 

is estimated as slightly less than one percent per year. This really comes as no surprise, as 

growth in Park City has been very rapid throughout the last twenty years. Growth would be the 

primary reason that Park City has attracted the attention of DAQ. 

Despite the high rate of growth, there is not enough weight of evidence to determine that Park 

City be declared an area of nonattainment unto itself. Nor will Utah recommend that Park City 

be included in the Northern Wasatch Front nonattainment area. A designation of 

“unclassifiable” would be more appropriate for this area. However, Park City is within the 

modeling domain, and all emissions from this county will be included in the modeling used to 

develop the SIP for ozone. Any source in Park City found to have a significant impact on the 

nonattainment area will be controlled as if it were in the nonattainment area. 
37

Heber Valley, Wasatch County 

Heber Valley lies East of the Wasatch Mountains, and Southeast of Park City. The Heber Valley 

is primarily a farming community with Heber City at its center. It is meteorologically distinct 

from the Wasatch Front, and is similar to Park City in terms of its topography. It is situated in a 

relatively high elevation valley that experiences occasional temperature inversions during the 

winter. 

There is minimal air movement between Park City and the Heber Valley, but due to recent 

increased home prices in Park City, the Heber Valley has become somewhat of a bedroom 

community to both Park City and the more populous Utah Valley area to the west. There is 

presently no I/M program implemented in Wasatch County. Utah statute prohibits such a 

program unless the area is not attaining one of the pertinent NAAQS. 

Heber Valley, Utah looking southwest over Deer Creek Reservoir toward Provo Canyon 

Figure 12 indicates that there are no major point sources in the Heber Valley that would warrant 

special consideration. Notwithstanding, it would be highly unlikely that a significant degree of 

improvement in emissions control would be achievable only through the SIP process. Utah’s 

permitting rules already require Best Available Control Technology on all sources, major or 

minor, constructed after 1971. 

The Heber Valley is a growing area. Growth estimates for the valley may be approximated by 

looking at the countywide estimates for Wasatch County presented in Table 6 in factor 5. The 

Heber Valley is really the only populous region of Wasatch County, so it may be assumed that 

almost all of the countywide growth will take place in and around the valley. Relative to the 

2000 census, growth in Wasatch County is occurring at more than five percent per year. Again, 

this is roughly twice the average for the entire state (roughly two and a half percent per year). 
38

As with Park City, rapid growth in a valley setting is not sufficient reason to recommend Heber 

as an area of nonattainment. A designation of “unclassifiable” would be more appropriate. 

However, the Heber Valley is within the modeling domain, and all emissions from this area will 

be included in the modeling used to develop the SIP for ozone. Any source in the Heber Valley 

or Wasatch County found to have a significant impact on the nonattainment area will be 

controlled as if it were in the nonattainment area. 

Tooele Valley, Tooele County 

Figures 9, 10 and 11 reveal the layout surrounding the Tooele Valley which includes the City of 

Tooele and its neighboring towns of Grantsville and Stansbury Park. These municipalities reside 

to the West of Salt Lake County in the northern half of a valley bound on the east and south by 

the Oquirrh Mountain Range and on the west by the Stansbury Mountain Range. The Great Salt 

Lake is the northern boundary of this valley. 

This topographical backdrop becomes important when discussing air movement between the Salt 

Lake and Tooele valleys. During a typical ozone episode in the Salt Lake Valley, the Oquirrh 

Mountains hinder any direct air movement between the two valleys. Diurnal air flows typically 

moves ozone plumes from the Salt Lake Valley northwestward out and over the Great Salt Lake. 

When the afternoon on-shore flow kicks in, sometimes there is just enough northward 

component to the wind to blow a fraction of the ozone plume into the Tooele Valley. This 

phenomenon has been verified on several occasions by monitoring the timing of ozone 

concentrations at Salt Lake Valley monitors, the Beach monitor and the Tooele monitor. 

Tooele Valley looking southeast from the eastern slopes of the Stansbury Mountains. Tooele City is 

located at mouth of the canyon at left center of photo. Grantsville is in the foreground. 
39

DAQ has been monitoring ozone in the Tooele Valley since 2005. A look at Table 1 for the 

Tooele monitoring site shows that, based on 2006-2008 data, the area has a decreasing ozone 

trend and that the area is currently attaining the new ozone NAAQS. 

If the Tooele Valley area were more geographically removed from the core Northern Wasatch 

Front nonattainment area, DAQs’ initial inclination would be to recommend a designation of 

“unclassifiable” and wait for more data. However, given its proximity to the core area, we will 

consider additional information. 

Figure 12 shows that it is far more likely that any potential impact due to industrial point sources 

would be directed from Salt Lake County into Tooele County rather than the other way around. 

This would be evaluated during the course of SIP development. The only truly large point 

source in Tooele County is U.S. Magnesium LLC, located more than 30 miles from either Tooele 

or the Wasatch Front. A 1997 Wasatch Front Ozone Study6

 showed that chlorine emissions from 

U.S.Magnesium do not significantly influence ozone formation in either Salt Lake or Tooele 

County. In addition, Utah’s permitting rules already require Best Available Control Technology 

on all sources, major and minor, constructed after 1971. It is unlikely that a significant degree of 

improvement in emissions control would be achieved by designating the area as nonattainment. 

Growth estimates for this area may be approximated by looking at the countywide estimates for 

Tooele County presented in Table 6. The Tooele Valley is really the only populous region of 

that county, so it may be assumed that the majority of the countywide growth will take place in 

and around Tooele Valley. Relative to the 2000 census, growth in Tooele County is occurring at 

more than four and a half percent per year. Once again, this is roughly twice the average for the 

entire state, but actual numbers are very small when compared to more populous areas. This 

would seem to indicate that growth will generally take place in and around previously developed 

areas, but that growth will be more rapid in the peripheral areas that are not already built out. 

Tooele might be considered just such an area. 

Commuting patterns represent another factor to be considered in this situation. According to 

information compiled for the 2000 census “Journey to Work” data7

, Tooele County has 7,397 

commuters that travel to one of the three counties comprising the northern Wasatch Front 

(Weber, Davis, and Salt Lake). By contrast, there are 9,784 commuters that travel only within 

Tooele County. This confirms that Tooele is very much a bedroom community. One might 

suspect a significant impact within the Wasatch Front from cars originating in Tooele County. 

The Journey to Work data also reports that there are 619,397 commuters traveling only within 

the northern Wasatch counties. From this it can be determined that the influx of cars from 

Tooele accounts for only about 1.2% of all commuter trips along the Wasatch Front. 

Given the factors discussed above, DAQ is recommending that the Tooele County townships 

identified in Figure 12 be left out of the nonattainment area for the Wasatch Front. Of all the 

factors discussed so far, the air quality data collected in Tooele should be given the most weight. 

If the data collected here ultimately indicates that a nonattainment designation would in fact be 

____________________ 

6. “Wasatch Front Ozone Study,” prepared for the Utah Department of Environmental Quality 

by ENVAIR and Alpine Geophysics, LLC, Volume 1, September 12, 1997 

7. http:www.census.gov/population/www/cen2000/commuting.html#UT 
40

appropriate, then it will be addressed specifically for this area at that time. For now, it is 

recommended that the area be designated as “attainment.” However, Tooele County is within 

the modeling domain, and all emissions from this county will be included in the modeling used 

to develop the SIP for ozone. Any source in Tooele County found to have a significant impact 

on the nonattainment area will be controlled as if it were in the nonattainment area. 

Brigham City, Box Elder County 

The geographical and topographical layout of Brigham City can be seen clearly in Figures 9 and 

10. Brigham City and its neighbor Tremonton (a farming community located 15 miles 

northwest), sit adjacent to the northern end of the Wasatch Mountains in the low lying area near 

the Great Salt Lake. Willard Bay, a prominent feature of the Lake, extends toward the East just 

north of the border with Weber County (see Figure 11). 

DAQ has been monitoring ozone in Brigham City since 2000. Current three-year monitoring 

data indicate that the area is attaining the current ozone NAAQS by a very close margin. 

Looking east-northeast at Brigham City from west of I-15. 

Similar to the Tooele area, if this area were more geographically isolated, DAQ’s initial 

inclination would be to recommend a designation of “unclassifiable” and wait for more data. 

Geographically speaking however, Brigham City is located very close to the northern edge of a 

core area that DAQ will recommend as nonattainment to the current ozone standard. For this 

reason we need to consider some additional information. 
41

Looking more closely at emissions within this area, there are two major point sources worth 

mentioning. Nucor Steel is located just north of Tremonton, the uppermost township shown in 

Figure 12. As part of the permitting process, this source has already undergone a BACT review. 

There is no reason to believe that reclassification as a nonattainment area would have any affect 

on the allowable emissions for this source. Another source of note is Vulcraft, a steel 

manufacturing facility, located just west of Brigham City. It is primarily a source of VOC 

emissions, but its NOx emissions are negligible. It also underwent a BACT review as part of its 

permit application. 

Growth estimates for Brigham City fall within the countywide estimates for Box Elder County 

presented in Table 6. Brigham City and Tremonton are the only populous regions of that county, 

so it may be assumed that almost all of the countywide growth will take place within this general 

area. Relative to the 2000 census, growth in Box Elder County is occurring at about 2.3 percent 

per year. This is a little less than the average for the entire state (roughly two and a half percent 

per year). While Brigham City might be considered as the northern extent of the Wasatch Front, 

it is removed from the northern urbanized core of that area by about 20 miles of farmland. 

Likewise, Tremonton is removed from Brigham City by about 15 miles of farmland. 

Commuting patterns represent another factor to be considered for the Brigham City area. 

Looking again at the 2000 census Journey to Work data, Box Elder County has 3,590 commuters 

that travel to one of the three counties (Weber, Davis, and Salt Lake) that make up the northern 

Wasatch Front core area. Actually the impact from this factor is even less that the impact from 

Tooele County commuting traffic. The Journey to Work data shows that only 3,590 commuters 

travel into the Northern Wasatch Front area counties for work. This amounts to approximately 

only 0.6 percent of the total travel within these core counties. 

Given the factors discussed above, DAQ is recommending that the townships identified in Figure 

12, within Box Elder County, not be included within the Northern Wasatch Front nonattainment 

area. 

Of all the factors discussed so far, air quality data collected in Brigham City should be given the 

most weight. If the data collected here ultimately indicates that a nonattainment designation 

would in fact be appropriate, then it will be addressed specifically for this area at that time. For 

now, it is recommended that the area be designated as “unclassifiable.” However, Brigham City 

and Box Elder County are within the modeling domain, and all emissions from this county will 

be included in the modeling used to develop the SIP for ozone. Any source in Box Elder County 

found to have a significant impact on the nonattainment area will be controlled as if it were in the 

nonattainment area. 

Utah County 

Utah County lies directly to the south of Salt Lake County. They are separated by a semiformidable elevation barrier of about five to eight-hundred feet (see figures 1 and 11). Air 

movement between the two counties does exist; however, this barrier tends to keep that 

movement to a minimum. The diurnal mountain-valley flow in Utah County tends to be more 

east-west with only an occasional north-south component. 

Concentrations of ozone precursors in Utah County have been steadily decreasing for the last 

decade even though the population of the county has increased. In 2002, Geneva Steel 
42

Corporation, the largest contributor to both ozone and particulate pollution in Utah County, 

ceased operations. In 2006 Ensign-Bickford, a large explosives manufacturer also ceased 

operations. From Table 1, we see that ozone concentrations at all three monitors located in Utah 

County show a slow but steady decrease over the past three years and that the area is currently 

attaining the new ozone NAAQS. 

Figure 12 shows that it is far more likely that any potential impact due to industrial point sources 

would be directed from Salt Lake County into Utah County rather than the other way around. 

This would be evaluated during the course of SIP development. The only significant VOC point 

source currently located in Utah County is the Pacific States Pipe Casting facility located south 

of Provo. Brigham Young University, also located in Provo, is the only other point source in the 

county and its VOC contribution to the inventory is minimal (see appendix 2). Utah’s permitting 

rules already require Best Available Control Technology on all sources, major and minor, 

constructed after 1971. Hence, it is unlikely that a significant degree of improvement in 

emissions control would be achieved by designating the area as nonattainment. 

Most of Utah County’s population currently resides between Utah Lake and the Wasatch Range, 

extending from Lehi, northeast of Utah Lake, to Payson, southeast of Utah Lake. Areas of new 

development are beginning to emerge west of Utah Lake and between Spanish Fork and 

Santaquin in the south end of Utah Valley. Growth estimates for this area may be approximated 

by looking at the countywide estimates for Utah County presented in Table 6. 

Utah County looking northeast toward the Wasatch Range from Salem, Utah 

Commuting patterns represent another factor to be considered in this situation. According to 

information compiled for the 2000 census “Journey to Work” data6

, Utah County has 19,318 

commuters that travel to one of the three counties comprising the northern Wasatch Front 

(Weber, Davis, and Salt Lake). By contrast, there are 140,834 commuters that travel only within 
43

Utah County. This confirms that a great majority of Utah County residents both live and work in 

the county. Additionally, the Journey to Work data indicates that there are 619,397 commuters 

traveling only within the northern Wasatch Front counties. From this it can be determined that 

the influx of cars from Utah County accounts for only about 3.2% of all commuter trips. 

The U.S. Census Bureau defines a CSA as an aggregate of adjacent Core Based Statistical Areas 

that are linked by commuting ties. The lack of commuting ties between Utah County and 

adjacent counties to the north, as well as other significant social and economic considerations 

delineated in the U.S. Census, is what prompted the Department of Commerce to designate Utah 

County as a separate MSA and not include it in the larger Salt Lake-Ogden-Clearfield CSA. 

Given the factors discussed above, DAQ is recommending that Utah County not be included in 

the nonattainment area for the Wasatch Front. Of all the factors discussed so far, the air quality 

data collected in Utah County should be given the most weight. If future data is collected that 

indicates that a nonattainment designation would be appropriate, it will be addressed specifically 

at that time. For now, it is recommended that Utah County be designated as “attainment.” 

However, Utah County is within the modeling domain, and all emissions from this county will 

be included in the modeling used to develop the SIP for ozone. Any source in Utah County 

found to have a significant impact on the nonattainment area will be controlled as if it were in the 

nonattainment area. 

St. George, Washington County 

As can be seen in Figures 2 and 3, there is one metropolitan area in southwestern Utah that 

deserves some discussion. This area is generally referred to as St. George, after the largest city 

in the area. The area is made up of the cities of St. George, Bloomington, Washington, Santa 

Clara, Hurricane and several other smaller towns. 

Based on the monitoring requirements of 40 CFR Part 58, St. George does not presently have a 

large enough population to require a federal reference monitor for ozone. Nevertheless, DAQ 

has conducted “survey” monitoring in St. George City since 2004. In 2008 the “survey” monitor 

was relocated about two miles northwest to the town of Santa Clara to eliminate any effect of 

NOx scavenging from nearby Interstate 15 and to give a better indication of ozone transport from 

the Las Vegas area. Results of this survey monitoring from the combined St. George (2006-

2007) and Santa Clara (2008) monitors indicate that summer ozone values have remained well 

below the current 75 ppb standard. Actual results for the 2006-2008 monitoring seasons from 

the St George and Santa Clara sites show that the three-year average of the 4th highest ozone 

concentration at the monitors was 64 ppb. There is also a CASTNet monitor located near the 

south entrance to Zion National Park; the three year average of the 4th highest ozone 

concentrations monitored there is 73 ppb (see Table 2). This difference can be explained by 

severe wildfires in 2005 and again in 2006 just west of the Zion monitor. In one instance, 

confirmed by National Park Service officials, the wildfire actually burned right up to the 

monitoring site. 

The St. George area lies at an elevation of only 2,600 feet MSL on the periphery of the Mojave 

Desert. There are mountainous areas to the north and west, but the area is not confined and does 

not stagnate here like it does in the lower valleys along the Wasatch Front. 

 
44

 St. George looking northeast, approximately 35 miles, toward Entrance to Zion National Park 

The St. George area has seen significant growth, as a retirement community, over the past twenty 

years and this growth is expected to continue, as noted in Table 6, for the foreseeable future. 

Based on the results of “survey” monitoring in the center of the St. George area, and also the 

monitoring results at the Zion National Park CASTNet monitor, DAQ will recommend a 

classification of “attainment/unclassifiable” for this area. DAQ will continue “survey” 

monitoring at the Santa Clara site and may install a federal reference monitor in the area in the 

future. 

San Juan County 

San Juan County is located in the southeast corner of Utah. This county is part of the FourCorners region, and borders the States of Colorado, New Mexico, and Arizona. The southern 

portion of San Juan County is part of the Navajo Nation. San Juan County is sparsely populated 

and oil and gas production is the primary source of emissions in the area. There is one major 

source located in the northeastern portion of the county, the Lisbon Natural Gas Processing Plant 

operated by EnCana Oil and Gas (USA) Inc. The oil and gas fields in San Juan County have 

been producing for many years, and production has been decreasing steadily over the last decade 

as can be seen in Figure 13. A significant portion of the oil and gas production in the county is 

occurring on tribal land under the jurisdiction of the Navajo Nation. 
45

Oil and Gas Production in San Juan County, Utah

-

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

1980 1985 1990 1995 2000 2005 2010

barrels oil/MCF gas

Oil 

Natural Gas

Figure 13. Oil and Gas Production in San Juan County, Utah

DAQ does not have an ozone monitor in San Juan County, however, the National Park Service 

maintains a CASTNet monitor in Canyonlands National Park in the northern part of the county. 

The 3-year average for this monitor is 0.071 ppm (see Table 2), and is an indicator that the 

county is attaining the ozone standard. 

San Juan County in Utah adjoins San Juan County in New Mexico where ozone values just 

above the standard have been measured at the Navajo Dam site. Emissions from San Juan 

County, Utah are unlikely to significantly contribute to ozone concentrations at this monitor. 

The Navajo Dam monitoring site is located approximately 80 miles from the Utah border, and 

two ozone monitors that are located between the Utah border and Navajo Lake monitor are 

attaining the standard. There has been significant oil and gas development in the Four Corners 

region in the last decade, but this has occurred primarily to the south and east of Utah’s border, 

in Colorado and New Mexico, and production has been declining in Utah. The 2002 base year 

inventory (plan02b) that was compiled by the Western Regional Air Partnership (WRAP) shows 

oil and gas area source emissions for San Juan County Utah to be 286 tons per year NOx and 

1,477 tons per year VOC. In comparison, oil and gas area source emissions for San Juan County 

New Mexico were 20,041 tons per year NOx and 60,178 tons per year VOC. 
46

Canyonlands National Park, San Juan County, Utah 

Based on monitoring data in the area, ozone levels are below the NAAQS, and the limited 

contribution of emissions from Colorado and New Mexico, San Juan County Utah should be 

designated as attainment/unclassifiable for ozone. 
47

State Recommendations 

Wasatch Front 

As shown on Figure 14, Utah is recommending the establishment of one nonattainment area for 

ozone: The Northern Wasatch Front nonattainment area which includes all of Salt Lake 

County, all of Davis County and all portions of Weber County west of and including Townships 

5 & 6 North Range 1 West and all portions of Township 7 North Range 1 West that are in Weber 

County and west of the ridgeline that traces the Wasatch Mountains from the Southeast corner of 

the township to the easternmost extension of the county boundary. 

Figure 14. Recommended Ozone Nonattainment Area
48

Attainment/Unclassifiable Areas 

As shown on Figure 15, Utah is recommending that all portions of the State not identified as 

areas of nonattainment should be designated as either “Attainment” or “Unclassifiable” with 

respect to ozone. An exception to this recommendation is all Indian Country Lands within the 

State of Utah over which DAQ has no jurisdiction. Designation of those areas will be left to 

EPA’s discretion. 

Figure 15. Statewide Area Map showing Recommended Nonattainment Areas and Indian Lands 
49

Summary Table 

Table 9 provides a description of all areas of the State and the recommended designations they 

should carry with respect to ozone. The State does not make recommendations for any portions 

of any county designated as Indian Country. 

Table 9. Description of all Areas of Utah and Recommended Designations

County Attainment Unclassifiable Nonattainment Nonattainment Area 

Beaver X X 

Box Elder X 

Cache X 

Carbon X X 

Daggett X X 

Davis X Northern Wasatch Front 

Duchesne X X 

Emery X X 

Garfield X X 

Grand X X 

Iron X X 

Juab X X 

Kane X X 

Millard X X 

Morgan X X 

Piute X X 

Rich X X 

Salt Lake X Northern Wasatch Front 

San Juan X X 

Sanpete X X 

Sevier X X 

Summit X X 

Tooele X 

Uintah X X 

Utah X 

Weber All portions of 

Weber County not 

otherwise designated 

nonattainment 

All portions of Weber 

County west of and 

including T5N R1W 

and T6N R1W and all 

portions of T7N R1W 

that are in Weber 

County and west of the 

ridgeline that traces the 

Wasatch Mountains 

from the Southeast 

corner of the township 

to the easternmost 

extension of the county 

boundary 

Northern Wasatch Front 

Wasatch X X 

Washington X 

Wayne X X 
50

Supporting Documentation 

In addition to any technical information documenting the recommendation for area boundaries, 

EPA requested that each state provide the information identified below. The italicized text either 

provides or indicates where this information has been included with Utah’s recommendation. 

For nonattainment areas: 

• The ozone design value(s) for the area 

• The 3-yr period represented by the design value(s) 

All of the information identified above was included in Table 1. 

• Site locations and ID numbers (see Table 10) 

Table 10. DAQ Monitor Network Locations (*Denotes monitors that are currently inactive or in 

the process of being repositioned)

Site ID Location Address County 

49-003-0003 Brigham City 140 W. Fishburn Box Elder 

49-005-0004 Logan 125 W. Center St. Cache 

49-011-0004 Bountiful 171 W. 1370 N. Davis 

49-035-0003 Cottonwood 5715 S. 1400 E. Salt Lake 

49-035-2004 Beach 12100 W.1200 S. Salt Lake 

49-035-3006 Hawthorne 1675 S. 600 E. Salt Lake 

49-035-3007 West Valley* 3275 W. 3100 S. Salt Lake 

49-035-3008 Herriman* 12950 S. 5600 W. Salt Lake 

49-045-0003 Tooele 434 N. 50 W. Tooele 

49-049-0002 North Provo 1355 N. 200 W. Utah 

49-049-5008 Highland 10865 N. 6000 W. Utah 

49-049-5010 Spanish Fork 312 W. 2050 N Utah 

49-057-0007 Washington Terrace* 4601 S. 300 W. Weber 

49-057-0002 Ogden #2 228 E. 32nd St. Weber 

49-057-1003 Harrisville 425 W. 2550 N. Weber 

For attainment/unclassifiable and nonattainment areas: 

• Names of counties and tribal lands included, (See Summary Table and Figure 15) 

 

• If partial counties or portions of tribal lands are included, the boundary definition/description 

is presented in Figure 15 

o including a legal definition of the area (See Summary Table and Figure 15)

o an explanation of how the boundary is consistent with Sect. 107(d)(1) of the CAA 
51

Paragraph (A) of section 107(d)(1) of the Clean Air Act describes the three 

designations an area may carry (see page 10) Utah’s recommendations are 

consistent with the definitions provided therein. 

The areas recommended for designation of “Nonattainment” are areas represented 

by monitored ambient air data that does not meet the primary (or secondary) 8-hr 

standard for ozone. The recommendations for these areas were not completed until 

surrounding areas were evaluated to see whether they were impacting upon the 

areas. 

The areas recommended for designation of “Attainment” are represented by 

monitored ambient air data that does meet all the primary and secondary standards 

for ozone. 

The areas recommended for designation of “Unclassifiable” are areas for which 

there is insufficient data to draw any conclusions. 

Names of contacts 

 M. Cheryl Heying Dave McNeill 

 Director Section Manager 

 Utah Division of Air Quality SIP Section 

 (801) 536-4022 (801) 536-4037 

 Robert Clark Kimberly Kreykes 

 Environmental Scientist Environmental Planning Consultant 

 SIP Section SIP Section 

 (801) 536-4435 (801) 536-4042 
52

Appendix 1 

2005 Emission Summary by County 

County Source NOx VOC County Source NOx VOC

Beaver Area Source 58.22 295.40 Piute Area Source 13.01 153.57

Non-Road Mobile 3238.97 44.43 Non-Road Mobile 6.32 76.97

On Road Mobile 1119.45 472.10 On Road Mobile 118.90 52.48

Point Source 42.30 3.36 Point Source 0 0

Total 1548.95 815.29 Total 138.24 283.02

 

Box Elder Area Source 535.24 2992.59 Rich Area Source 48.14 223.45

Non-Road Mobile 553.15 2471.33 Non-Road Mobile 8.41 375.00

On Road Mobile 3976.10 1523.03 On Road Mobile 188.04 95.46

Point Source 553.36 395.78 Point Source 0 0

Total 5617.85 7382.73 Total 244.58 693.91

 

Cache Area Source 356.86 2437.75 Salt Lake Area Source 1901.72 19963.22

Non-Road Mobile 666.98 612.97 Non-Road Mobile 5184.10 5452.65

On Road Mobile 2928.08 1269.39 On Road Mobile 23310.31 9574.62

Point Source 139.74 143.84 Point Source 7710.29 2130.76

Total 4091.66 4463.96 Total 38106.41 37121.25

 

Carbon Area Source 86.33 482.12 San Juan Area Source 35.39 516.76

Non-Road Mobile 939.09 134.89 Non-Road Mobile 59.24 546.10

On Road Mobile 992.42 363.57 On Road Mobile 1057.86 470.43

Point Source 3981.86 66.30 Point Source 473.29 67.32

Total 5999.70 1319.88 Total 1625.78 1600.60

 

Daggett Area Source 34.63 240.32 Sanpete Area Source 120.29 619.97

Non-Road Mobile 19.37 144.47 Non-Road Mobile 47.05 177.06

On Road Mobile 113.62 74.29 On Road Mobile 981.81 566.38

Point Source 749.18 66.44 Point Source 32.79 2.68

Total 916.81 525.52 Total 1118.94 1366.09

 

Davis Area Source 340.98 5534.81 Sevier Area Source 144.36 685.69

Non-Road Mobile 1824.27 1635.73 Non-Road Mobile 170.84 402.08

On Road Mobile 6423.47 2904.61 On Road Mobile 2975.83 675.07

Point Source 2152.47 1559.60 Point Source 132.05 11.27

Total 10741.19 11634.75 Total 3423.09 1774.11

 

Duchesne Area Source 80.34 747.49 Summit Area Source 155.96 913.20

Non-Road Mobile 148.48 277.51 Non-Road Mobile 1386.09 422.81

On Road Mobile 979.01 372.29 On Road Mobile 2148.08 833.84

Point Source 656.54 260.62 Point Source 472.20 28.37

Total 1864.36 1657.91 Total 4162.33 2198.21

 
53

Source NOx VOC County Source NOx VOC Source

Emery Area Source 60.28 372.35 Tooele Area Source 298.21 2157.66 

Non-Road Mobile 160.31 63.08 Non-Road Mobile 1337.40 968.26 

On Road Mobile 1595.53 663.40 On Road Mobile 2647.99 1767.52 

Point Source 28206.90 236.27 Point Source 1210.20 509.42

Total 30023.02 1335.11 Total 5493.79 5402.86

 

Garfield Area Source 71.29 465.10 Uintah Area Source 111.08 1018.01

Non-Road Mobile 76.77 656.26 Non-Road Mobile 174.94 233.48

On Road Mobile 478.18 208.14 On Road Mobile 1394.03 571.08

Point Source 7.40 0.93 Point Source 150.19 50.68

Total 633.64 1330.42 Total 1830.25 1873.25

 

Grand Area Source 15.61 285.30 Utah Area Source 780.77 9391.55

Non-Road Mobile 175.71 904.50 Non-Road Mobile 2674.25 2087.73

On Road Mobile 1042.04 572.12 On Road Mobile 9483.84 5116.22

Point Source 377.81 68.68 Point Source 652.69 719.84

Total 1611.18 1830.60 Total 13591.55 17315.33

 

Iron Area Source 187.91 1193.72 Wasatch Area Source 46.20 457.91

Non-Road Mobile 194.27 223.96 Non-Road Mobile 206.76 131.49

On Road Mobile 2815.06 1058.78 On Road Mobile 907.21 445.65

Point Source 72.07 99.09 Point Source 67.23 5.95

Total 3269.32 2575.54 Total 1227.40 1041.00

 

Juab Area Source 123.04 785.43 Washington Area Source 841.90 7193.25

Non-Road Mobile 805.06 200.55 Non-Road Mobile 724.59 1285.40

On Road Mobile 2292.07 695.29 On Road Mobile 4524.91 1904.83

Point Source 1536.13 62.85 Point Source 196.30 57.19

Total 4756.30 1744.12 Total 6287.69 10440.66

 

Kane Area Source 25.89 196.92 Wayne Area Source 31.00 89.49

Non-Road Mobile 58.96 715.20 Non-Road Mobile 19.71 212.24

On Road Mobile 552.50 272.59 On Road Mobile 157.71 85.20

Point Source 0 0 Point Source 15.97 1.24

Total 637.35 1184.71 Total 224.39 388.17

 

Millard Area Source 95.96 578.36 Weber Area Source 304.56 4535.39

Non-Road Mobile 1289.10 685.07 Non-Road Mobile 1674.89 1238.53

On Road Mobile 2315.55 797.10 On Road Mobile 4479.23 2399.52

Point Source 23316.67 130.85 Point Source 421.78 172.80

Total 27017.27 2191.38 Total 6880.46 8346.23

 

Morgan Area Source 26.83 263.76 Statewide Area Source 6932.02 64790.53

Non-Road Mobile 1297.00 99.52 Totals Non-Road Mobile 22212.08 22479.27

On Road Mobile 513.63 199.55 On Road Mobile 82449.48 36277.54

Point Source 1333.03 50.98 Point Source 74660.42 6903.09

Total 3170.50 613.81 Total 186,254.0 130,450.4
54

Appendix 2 

Point Sources located in CSA/MSA Factor 9 

Site ID Plant County VOC 

(tpy) 

NOx 

(tpy) 

10007 Holcim (US) Inc - Devil’s Slide Morgan 49.4 1,324.5 

10008 Nucor Steel Box Elder 79.6 238.9 

10028 Vulcraft - Steel Products Manufacturing Box Elder 239.6 4.8 

10119 Chevron Salt Lake Refinery Davis 257.7 783.8 

10121 Hill Air Force Base - Main Base Davis 247.3 142.2 

10122 Flying J Refinery Davis 384.7 374.5 

10123 Holly - Phillips Refinery Davis 198.4 324.6 

10124 Silver Eagle Refining Davis 178.0 85.2 

10129 Wasatch Waste Mgmt County Landfill Facility Davis 24.2 280.8 

10156 Utility Trailer Manufacturing Davis 106.7 38.8 

10303 Ash Grove Cement Company Juab 57.5 1,397.6 

10335 Tesoro Salt Lake City Refinery Davis 268.2 446.5 

10346 Kennecott Smelter & Refinery Salt Lake 8.7 154.7 

10565 Geneva Rock Pt of the Mountain Facility Salt Lake 16.3 86.0 

10571 Kennecott Mine & Concentrator Salt Lake 344.6 3,750.0 

10572 Kennecott Power Plant/Lab/Tailings Salt Lake 11.9 2,066.6 

10676 Utelite Corp - Shale Processing Summit 2.6 235.2 

10716 US Magnesium - Rowley Plant Tooele 452.5 746.9 

10725 Clean Harbors Aragonite - Hazardous Waste Incineration Tooele 6.2 131.9 

10790 Brigham Young University Main Campus Utah 9.7 98.8 

10794 Pacific States Pipe Casting Plant Utah 303.5 65.0 

10973 PacifiCorp Little Mountain Power Plant Weber 1.7 200.6 

11339 Desert Chemical Depot Tooele 4.0 108.4 

11841 Pepperidge Farm Commercial Bakery Cache 120.5 4.4 

12519 Tooele Power - Desert Power Plant Tooele 2.7 144.7