# Idaho Area Designation Recommendations for the 2006 PM 2.5 

# NAAQS

State of Idaho Department of Environmental QualityIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS ii 

## Idaho Area Designation Recommendations for the 2006 PM 2.5 

## NAAQS

Contents Executive Summary.............................................................................................................. .......... 1 1. Purpose and Background ..................................................................................................... ...... 2 2. Applicable Guidance........................................................................................................ .......... 2 3. Ambient Air Quality Data................................................................................................... ....... 2
4. Nonattainment Boundaries for the Areas Violating the 24-hour PM 2.5 Standard – Nine-Factor Analysis....................................................................................................................... .............. 5 4.1 Pinehurst – Shoshone County Nonattainment Area Boundaries ........................................ 6 Proposed geographic boundaries for the Pinehurst NAA....................................................... 23 4.2 Franklin County – Cache Valley Nonattainment Area Boundaries.................................. 24 Proposed geographic boundaries for the Fran klin County – Cache Valley Nonattainment Area........................................................................................................................... .............. 35 5. Summary..................................................................................................................... .............. 37 6. References.................................................................................................................. ............... 37 Appendix A – All Designated and N on-Designated Area Descriptionss ..................................... 38 Appendix B – Supporting Documentation Locations................................................................... 47
Names of Contacts .............................................................................................................. .... 48 

### List of Tables
Table 1. Annual PM 2.5 Design Values a .......................................................................................... 4
Table 2. 24-hour PM 2.5 Design Values a ......................................................................................... 4 Table 3. Annual emissions after prescribed and wild fire emissions are deducted a ...................... 7 Table 4. 24-hour PM 2.5 monitoring data from continuous monitors in counties adjacent to Shoshone County .......................................................................................................... 8 Table 5. County populations and population densities .................................................................. 9Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS iii Table 6. Annual VMT (vehicle miles traveled) for Shoshone County and adjacent counties..... 12 Table 7. Population numbers, density, and gr owth figures for Shoshone County and adjacent counties ....................................................................................................................... 14 Table 8. Annual emissions after prescribed and wild fire emissions are deducted. .................... 26 Table 9. 2006 population densities for Franklin County and adjacent counties.......................... 27 Table 10. Annual VMT (vehicle miles traveled) for Franklin County and adjacent counties in both Idaho and Utah.................................................................................................... 30 Table 11. Population growth in th e Cache Valley from 2000 to 2006 ........................................ 32 Table 12. Population growth in Franklin County, Idaho from 2000 through 2006..................... 32 Table 13. Descriptions of all areas of the state and the designations .......................................... 39
Table 14. Monitor locations and ID numbers for PM 2.5 nonattainment areas ............................. 47 

### List of Figures Figure 1. Idaho PM 2.5 Ambient Air Monitoring Network. ............................................................. 3 Figure 2. Relationship of Franklin, Idaho and Logan, Utah FRM data......................................... 5 Figure 3. Location map showing Pinehurst and th e main valley of the Coeur d'Alene River, known as the Silver Valley. .......................................................................................... 6 Figure 4. Population densities fo r the area surrounding Pinehurst .............................................. 10 Figure 5. Roadways and interstate highway in and around Pinehurst. ........................................ 13 Figure 6. Temperature profiles measured at the Spokane, Washington airport on December 20, 2006, at 5:00am (left) and 5:00pm (right). ................................................................. 17 Figure 7. Windrose for Pinehurst, Ida ho, December 18 - 22, 2006, the period of a PM 2.5 stagnation episode....................................................................................................... 18 Figure 8. Wind patterns during another winter PM 2.5 stagnation episode in Pinehurst, Idaho, January 2 - 5, 2006...................................................................................................... 18 Figure 9. Annual windrose fo r 2006, Pinehurst, Idaho................................................................ 19 Figure 10. Windrose for Pinehurst , Idaho in the wintertime. Data from January, February, November, and December 2006. ................................................................................ 19 Figure 11. Pollution rose for Pinehurst, Ida ho for wintertime: November 2005 – March 2006. 20Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS iv Figure 12. Pollution rose for Pinehurst, Ida ho for wintertime: November 2006 – March 2007. 20 Figure 13. Modeling results of hyp othetical sources, showing that sources located in the Silver Valley do not contribute to a violation of the PM 2.5 standard in Pinehurst. ............... 21 Figure 14. Pinehurst PM 10 NAA (nonattainment area)................................................................ 22 Figure 15. Proposed geographic boundary for the Pinehurst PM 2.5 nonattainment area............. 24 Figure 16. Location map showing the Cache Va lley and the boundaries of Franklin County, Idaho and Cache County, Utah. .................................................................................. 25 Figure 17. Population density for the Cache Valley.................................................................... 28 Figure 18. Roadways in the Cache Valley................................................................................... 31 Figure 19. January 2004 temperature contour map with PM 2.5 concentration (yellow) and 1997 PM 2.5 National Ambient Air Quality St andard (green) (Martin, 2006)..................... 34 Figure 20. Average temperature profiles in Cache Valley during January 1 - 17, 2004 (Martin, 2006) .......................................................................................................................... . 34 Figure 21. Proposed geographic bo undaries for the Idaho porti on (Franklin County) of the proposed Cache Valley PM 2.5 nonattainment area...................................................... 36Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 1 

### Executive Summary In a July 20, 2007 letter, the Environmental Prot ection Agency (EPA) formally requested that Governor Otter submit a list of a ll areas of Idaho, including a recommendation for designation of each area, regarding attainment of the National Ambient Air Quality Standards (NAAQS) for fine particulate matter (PM 2.5 ). Designation recommendations must adhere to EPA policy. For areas designated as nonattainment, EPA recommends determining the nonattainment area (NAA) boundary on a case-by-case basis using the nine -factor analysis suggested in EPA guidance. The nine-factor analysis includes the following:
1. Emissions in areas potentially in cluded vs. excluded from the NAA
2. Air quality in areas potentially included vs. excluded from the NAA
3. Population density and the degr ee of urbanization, includi ng commercial development, in areas potentially included vs. excluded from the NAA
4. Traffic and commuting patterns
5. Expected growth (including extent , pattern, and rate of growth)
6. Meteorology (weather/transport patterns)
7. Geography/topography (mountain ranges or other air basin boundaries)
8. Jurisdictional boundaries (e.g., counties, air districts, reservations, etc.)
9. Level of control of emission sources. Based on monitoring data and the nine-factor analysis, DEQ recommends the following designations:

• Attainment – the airsheds of Benewah County, the Treasure Valley (Ada and Canyon Counties), and Pocatel lo (Bannock County).

• Nonattainment – the airsheds of Pinehurst (portion of Shoshone County) and the Idaho portion of the Cache Valley (a po rtion of Franklin County, Idaho).

• Unclassifiable – all remaining airsheds not identified above. DEQ used the nine-factor analysis to determin e the appropriate boundary for each of the areas designated as nonattainment. Figures 15 (pag e 24) and 21 (page 36) present the recommended NAA boundary for the Pinehurst area and the Ida ho portion of the Cache Valley, respectively. The legal descriptions of recommended de signated areas are included in Table 13 in Appendix A.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 2 

### 1. Purpose and Background The Environmental Protection Agency (EPA) revi sed the national ambient air quality standards (NAAQS) on October 17, 2006, to pr ovide increased protection of public health and welfare from fine particle pollution. The 24-hour standard for PM 2.5 (particles with an aerodynamic diameter of 2.5 micrometers or less) was re vised from 65 micrograms per cubic meter ( μ g/m 3 ) to 35 μ g/m 3 . The annual standard remained unchanged at 15 μ g/m 3 . The effective date for the new standard was December 18, 2006. The state of Idaho is required to submit to EPA a list of all areas in the state and to recommend designations for each area as “attainment,” “nonatta inment,” or “unclassifiable” with respect to the revised standard within one year of promul gation, in accordance with section 107(d)(1)(A) of the Clean Air Act. The recommendations are due to EPA by December 18, 2007.
The Clean Air Act allows that area s may be designated as follows: (i) nonattainment, for any area that does not meet (or that contributes to ambient air quality in a nearby area th at does not meet) the nati onal primary or secondary ambient air quality standard for the pollutant; (ii) attainment, for any area (other than an ar ea identified by clause (i)) that meets the national primary or secondary ambient air quality standard for the pollutant; and (iii) unclassifiable, for any area that cannot be classified on the basis of available information as meeting or not meeting th e national primary or secondary ambient air quality standard for the pollutant. This document provides Idaho’s recommendations for PM 2.5 designations of a ll areas within the state and fulfills Idaho’s requirements under se ction 107(d)(1)(A) of the Clean Air Act. 

### 2. Applicable Guidance The following EPA guidance was used for developing the PM 2.5 area designation recommendations:

• Area Designations for the Revised 24-hour Fine Par ticle National Ambient Air Quality Standard ; Memo from Robert Meyers, Acting Assistant Administrator to Regional Administrators, dated June 8, 2007.

• Designations for the Fine Particle National Ambient Air Quality Standards ; Memo from Jeffrey R. Holmstead, Assistant Admi nistrator to Regional Administrators, dated April 1, 2003. 

### 3. Ambient Air Quality Data EPA recommends that states identify violating areas using the most recent three years of air quality monitoring data (2004 – 2006). In general, violations are identif ied using data fromIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 3 federal reference method (FRM) and federal equi valent method (FEM) monitors that are sited and operated in accordance with 40 Code of Federal Regulations (CFR) Part 58, as revised on October 17, 2006. Idaho’s PM 2.5 ambient monitoring network is shown in Figure 1. Currently operating monitors are indicated with a star; all others were operated previously but are no longer.

Figure 1. Idaho PM 2.5 Ambient Air Monitoring Network.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 4 Tables 1 and 2 present the annual and 24-hour PM 2.5 design values, respectively, for those monitors that met the CFR requirements for determining PM 2.5 violations. The precise design value for each standard is described in the appropriate table. Table 1. Annual PM 2.5 Design Values a Weighted Annual Arithmetic Mean 3-Year Average of Annual Means c City County MSA b 2004 2005 2006 2004 – 2006 Pocatello Bannock Pocatello, ID 8.69 8.18 6.36 7.7
St. Maries Benewah N/A 9.30 9.51 9.69 9.5 Logan, Utah d Cache Logan, UT - ID 15.17 12.95 8.54 12.2 Boise Ada Boise City – Na mpa Idaho 8.98 8.59 7.99 8.5 Nampa Canyon Boise City – Nampa Idaho 9.10 9.22 7.61 8.6
Pinehurst Shoshone N/A 12.04 12.71 11.52 12.1
a. Annual PM 2.5 design value is the 3-year average of the annual means. b. MSA – metropolitan statistical area c. A value of 15.1 or greater indicates a violation. d. The Logan, Utah monitor is included because the city of Franklin in Franklin County, Idaho is part of the Logan, UT-ID Metropolitan Statistical Area. The Franklin County monitor does not meet the CFR requirements for determining PM 2.5 violations.
Table 2. 24-hour PM 2.5 Design Values a PM 2.5 24-hour 98 th Percentile 3-Year Average of 98 th Percentiles c City County MSA b 2004 2005 2006 2004 – 2006 Pocatello Bannock Pocatello, ID 32.5 29.8 20.6 28
St. Maries Benewah N/A 24.8 34.3 32.9 31 Logan, Utah d Cache Logan, UT - ID 101.5 56.7 29.4 63 Boise Ada Boise City – Nampa Idaho 35.5 26.4 28.5 30 Nampa Canyon Boise City – Nampa Idaho 43.8 36.3 22.4 34
Pinehurst Shoshone N/A 35.7 45.7 33.5 38 a. 24-hour PM2.5 design value is the 3-year average of the 98th percentile for each year. b. MSA – metropolitan statistical area. c. A value of 36 or greater indicates a violation, and is indicated in bold face. d. The Logan, Utah monitor is included because the city of Franklin in Franklin County, Idaho is part of the Logan, UT-ID MSA. The Franklin County monitor does not meet the CFR requirements for determining PM2.5 violations.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 5 Based on the available monitoring data in Idaho that meets the 40 CFR Part 58 requirements for 2004 – 2006, only Pinehurst in Shoshone County ha s a design value exceeding the 24-hour PM 2.5 NAAQS. Therefore, DEQ recommends that por tions of Shoshone County be designated as nonattainment. DEQ does not have three consecutiv e years of monitoring data on wh ich to base an attainment decision for Franklin County. However, available monitoring data from Franklin County does show a significant relationship with da ta from the Logan monitor (Figure 2). Values from Franklin County data average about 90% of Logan values. This is consistent w ith the findings of a PM 2.5 saturation study conducted by Utah’s DEQ. Base d on the 2004-2006 data collected by the Logan monitor, the Cache County design value for the 24-hour NAAQS is 63 μ g/m 3 and it is appropriate to conclude that a portion of Fra nklin County should be included as pa rt of the area that violates the 24-hour NAAQS. Therefore, DEQ recommends a por tion of Franklin County be designated as nonattainment.

Logan v. Franklin, 2005 PM2.5 24-hour averages, all data

y = 0.9119x - 1.9131 R 2 = 0.8926

0 10 20 30 40 50 60 70 80 90

0 10 20 30 40 50 60 70 80 90 Logan, ug/m3Franklin, ug/m3

Figure 2. Relationship of Franklin , Idaho and Logan, Utah FRM data. 

### 4. Nonattainment Boundaries for the Areas Violating the 24-hour PM 2.5 

### Standard – Nine-Factor Analysis According to EPA’s June 2007 Guidance Memorandum by Robert J. Meyers: “EPA believes that, in making their boundary reco mmendations for nonattainment areas, States and Tribes should evaluate each area on a ca se-by-case basis. The CAA requires that a nonattainment area must include not only the area that is violating the st andard, but also nearbyIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 6 areas that contribute to the viol ation. Thus, for each monitor or group of monitors that indicate violations of a standard, EPA will establish nonatt ainment boundaries that cover a sufficiently large area to include both the area that violat es the standard and the areas that contribute to the violations. EPA recommends that States and Tribes base their boundary recommendations for violating areas on an evaluation of the nine factors used in the prior PM 2.5 designations process, as well as on any other relevant factors or circ umstances specific to a particular area.” Both of Idaho’s proposed nonattainment counties are rural; therefore, it would not be appropriate to identify the entire counties as nonattainment. Instead, Idaho evaluated Pinehurst in Shoshone County and Franklin County using the nine-facto r analysis recommended in EPA guidance to determine the appropriate NAA boundary for eac h area. Both NAA boundaries must cover a sufficiently large area to include both the area that vi olates the standard and the areas that contribute to the violations. 4.1 Pinehurst – Shoshone County Nonattainment Area Boundaries As can be seen in Figure 3, the town of Pinehurst is located in a sm all, enclosed, bowl-shaped valley in Shoshone County, Idaho. Based on air quality data for 2004-2006, the PM 2.5 FRM located at the Pinehurst Elementary School record ed violations of the 24-hour PM 2.5 standard, with a design value of 38 μ g/m 3 (Table 2).

Figure 3. Location map showing Pinehurst and the main valley of the Coeur d'Alene River, known as the Silver Valley.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 7 FACTOR 1: Emissions in areas potent ially included vs. excluded from the NAA There are no major particulate-em itting industrial sources located in Shoshone County; wildfire and prescribed burning are large cont ributors to regional emissions totals during spring, summer, and fall. Shoshone County has emissions totals similar to those of adjacent counties in Idaho and Montana (Table 3). Shoshone and these bordering countie s largely lack commercial and industrial development. The exceptions are Kootenai County's Coeur d'Alene area and the town of Sandpoint in Bonner County. Both of these areas have mu ch higher population densiti es and are home to several industrial poin t sources, so the emissions totals are higher. Both Coeur d'Alene and Sandpoint are at least 45 kilometers to the west of the Pinehurst area. The Idaho 2005 emissions inventory indicates sources of pollutants in Shoshone County are residential wood heating, tailpipe emissions, pave d road fugitive dust, and asphalt paving. With sparse roadway miles and low vehi cles miles travelled, wood heating of homes is the predominant emissions source in Pinehurst. However, Pinehu rst is surrounded by state owned and privately owned timber lands. Slash burning occurs on these lands and is a large emissions source in this area. Smoke generated from local slash burning activities has been directly linked to recent excursions of the PM 2.5 24-hour standard. Open burning of ya rd debris is also considered a significant cont ributor to PM 2.5 concentrations buildup in the Pinehurst airshed.
Table 3. Annual emissions after prescribe d and wild fire em issions are deducted a County SO x (TPY) NO x (TPY) NH 3 (TPY) VOC (TPY) PM 2.5 (TPY)
Shoshone 68 998 52 2963 289
Benewah 81 863 217 2029 208
Bonner 331 4440 272 6019 944
Clearwater 74 837 227 2043 128
Kootenai 458 6339 1290 10628 2000
Latah 191 2278 813 3770 579 Mineral (MT) 87 933 133 609 195 Sanders (MT) 75 525 229 617 298 a. http://www.epa.gov/ttn/naaqs/pm/pm 25_2006_techinfo.ht ml (2005 NEI) SO x– oxides of sulphur; NO x– oxides of nitrogen; NH 3 – ammonia; VOC – volatile organic compound; PM 2.5 – particulate matter with an aerodynamic diameter of 2.5 micrometers or less; TPY – tons per yearIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 8 FACTOR 2: Air quality in areas potent ially included vs. excluded from the NAA As seen in Table 2, the monitor located in Pinehurst has a 24-hour design value of 38 μ g/m 3 , which violates the 24-hour PM 2.5 standard. Currently, no other PM 2.5 air quality data, us ing either FRM or continuous monitors, have been collected at any other location w ithin Shoshone County. DEQ operates real-time continuous PM 2.5 particulate monitors in several counties adjacent to Shoshone County. The data gathered from these c ontinuous monitors indicate that these adjacent counties do not violate the PM 2.5 standard. Table 4 presents th e data from continuous monitors from counties adjacent to Shoshone County, along with data from the monitor located in Pinehurst. Table 4. 24-hour PM 2.5 monitoring data from continuous monitors in counties adjacent to Shoshone County
PM 2.5 24-hour 98 th Percentile ( μ g/m 3 ) 3-Year Average of 98 th Percentiles County (City) a 2004 2005 2006 2004 – 2006 Shoshone (Pinehurst) b 40.2 39.6 33.8 38 Latah (Moscow) 14.6 11.3 26.9 18 Kootenai (Coeur d’ Alene) 26.7 24.1 27.5 26 Bonner (Sandpoint) 21.7 19.7 24.2 22 a. An FRM monitor is located in Benewah County (S t. Maries). The data for this monitor is shown in Table 2. b. A real-time continuous PM 2.5 monitor is co-located with the FRM monitor in Pinehurst.
FACTOR 3: Population density and the de gree of urbanization, including commercial development, in areas potentially included vs. excluded from the NAA As seen in Table 5, surrounding counties, with the exception of Kootenai, have low population densities. The town of Pinehurst has a highe r population density than its immediately surrounding area (Figure 4). Shoshone County has just over 13,000 residents. There are several small towns along the Interstate 90 (I-90) corr idor that bisects Idaho's pa nhandle along the Silver Valley. According to census data from the EPA technology transfer network (TTN), these towns range in size from the largest, Kellogg with 2,296 residents, to the second- largest, Pinehurst with 1,614, to Enaville, Gem, Kinston, and Silverton, which are small enough that they do not register in the census data.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 9 Table 5. County population s and population densities County 2006 Population County Size (km 2 ) 2006 Population Density (population per km 2 )
Shoshone* 13,180 6822.1 2 Benewah 9,347 2009.9 5 Bonner 41,275 4500.4 9 Clearwater 8,324 6375.4 1 Kootenai 131,507 3225.1 41 Latah 35,029 2788.7 13 Mineral (MT) 4,057 3159.5 1 Sanders (MT) 11,138 7154.3 2 * Town of Pinehurst, Idaho population: 1,614; Pinehur st, Idaho population density: approximately 700 population per km 2 . (See population density map in Figure 3.) Sources: http://www.census.gov/popest/counties/CO-EST2006-03.html for 2006 populations; http://www.census.gov/population/censusdata/90den_stco.txt for size.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 10Figure 4. Population densities forthe area surrounding Pinehurst(http://sedac.ciesin.columbia.edu:9080/entri/index.jsp; accessed July 1, 2007).Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 11 FACTOR 4: Traffic and commuting patterns Several counties surrounding Shoshone County have substantially higher annual vehicle miles traveled (VMT) than Shoshone County. The follow ing commuter information indicates that this travel is not crossing county or state borders in substantial am ounts, either into or out of Pinehurst or Shoshone County. Commuting information from the EPA TTN 2006 PM 2.5 technical data:

• Shoshone County, the county of intere st, has a total of 5,275 commuters.

- Commuters who remain in Shoshone County: 4,304

• Benewah County, an adjacent county, has a total of 3,427 commuters.

- Commuters from Benewah C ounty to Shoshone County: 78

- Commuters that remain in Benewah County: 2,875

• Bonner County, an adjacent county, has a total of 15,570 commuters.

- Commuters from Bonner Count y to Shoshone County: 16

- Commuters that remain in Bonner County: 12,968

• Clearwater County, an adjacent coun ty, has a total of 3,207 commuters.

- Commuters from Clearwater C ounty to Shoshone County: 3

- Commuters that remain in Clearwater County: 2,721

• Kootenai County, an adjacent county, has a total of 49,351 commuters.

- Commuters from Kootenai C ounty to Shoshone County: 377

- Commuters that remain in Kootenai County: 38,744

• Latah County, an adjacent county, has a total of 16,837 commuters.

- Commuters from Latah Count y to Shoshone County: 34

- Commuters that remain in Latah County: 13,249

• Mineral County (Montana), an adjacent county, has a total of 1,629 commuters.

- Commuters from Mineral C ounty to Shoshone County: 6

- Commuters that remain in Mineral County: 1,220

• Sanders County (Montana), an adjacent county, has a total of 3,902 commuters.

- Commuters from Sanders C ounty to Shoshone County: 0

- Commuters that remain in Sanders County: 3,337Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 12 Table 6 presents the VMT for Shoshone County a nd the bordering counties located in both Idaho and Montana. The roadways in and around Pinehur st are shown in Figure 5, along with I-90 just north of Pinehurst. The average annual VMT for the section of I-90 between Pinehurst and Smelterville is 8.18 million. The pr ojected annual growth for the tra ffic on this section of I-90 is 4.5%. Table 6. Annual VMT (vehicle miles travel ed) for Shoshone County and adjacent counties County VMT (Millions)
Shoshone 226.8688
Benewah 153.2637
Bonner 629.6788
Clearwater 146.7322
Kootenai 852.3298
Latah 572.4237 Mineral (MT) 202.5482 Sanders (MT) 96.386

Source: EPA TTN 2005_vmt_county_level-1.xlsIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 13Figure 5. Roadways and interstatehighway in and around Pinehurst.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 14 FACTOR 5: Expected growth (including extent, pattern, and rate of growth) According to 2000 and 2006 census data (Table 7), the population of Shoshone County has decreased by 4.1%. However, data from the Id aho Department of Comm erce indicates a slight increase (1.3%) in Pinehurst population from 2005 to 2006. ( http://cl.idaho.gov/data/ census/CityPops2000-2005.xls ) Population growth is taking place in nearby Koot enai and Bonner counties. With its lakeside mountain setting, the Sandpoint area in Bonner County has become attractive to retirees, and it also provides employment; there are a few point sources located in the area. Coeur d'Alene is showing rapid growth in Kootenai County due to the same reasons. Furthermore, Coeur d'Alene is near Spokane, Washington, and it becomes even more attractive for relocating workers. These two population centers, Sandpoint and Coeur d'Alene, are more than 45 kilometers away from Pinehurst. Population and population growth figures for Shoshone County and the adjacent counties are presented in Table 7. Table 7. Population numbers, density, and growth figures for Shoshone County and adjacent counties

County 2000 Population 2006 Population Growth 2000 - 2006 % Change
Shoshone* 13,747 13,180 -567 -4.1 Benewah 9,196 9,347 151 1.6 Bonner 37,031 41,275 4,244 11.5 Clearwater 8,895 8,324 -571 -6.4 Kootenai 109,550 131,507 21,957 20 Latah 34,861 35,029 168 0.5 Mineral (MT) 3,883 4,057 174 4.5 Sanders (MT) 10,253 11,138 885 8.6
* Town of Pinehurst, Idaho population: 1,614 (2006) ; Town of Pinehurst, Idaho population density (2006) approx. 700 pop. per sq. km (Figure3 * Town of Pinehurst, Idaho population: 1,614 (200 6); town of Pinehurst, Idaho population density (2006): approximately 700 population per km 2 . (See population density map in Figure 3.); town of Pinehurst, Idaho population change: -2.8% (2000 to 2006). Sources: http://factfinder.cens us.gov/servlet for 2006 populations; http://www.census.gov/populati on/censusdata/90den_stco.txt for size; http://www.citydata.com/city/Pinehurst-Idaho.html for city data.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 15 FACTOR 6: Meteorology (wea ther/transport patterns) AND FACTOR 7: Geography/topography (mountain ranges or other air basin boundaries) Factors 6 and 7 are discussed together because they are thoroughly interrelated. Pinehurst is located in a valley n ear the western end of the Silver Valley, a historic mining area along the south fork of the Coeur d’Alene River. The Silver Valley is about 22 miles long and varies from only one-tenth of a mile to slightly more than three-fourths of a mile wide. Elevation in the western end of the valley is 2,200 feet risi ng to 3,300 feet at the ea stern end. The city of Pinehurst sits in the Pine Creek Valley, which connects with the Silver Valley through a narrow gap. Figure 3 shows the relationship of Pinehurst and the Silver Valley. Although the climate in northern Id aho is often influenced by mo ist and relatively mild Pacific storms, occasional masses of arctic air can bring bitter cold weather during the winter months. When cold, stable air is advected into the re gion by arctic outbreaks or cold Pacific storms following the passage of a cold front, cold air becomes pooled in the na rrow mountain valleys of the region. Such cold air masses can further stab ilize when high pressure aloft overtakes the region. Under such a situation, a prolonged stro ng inversion layer (or layers) near the ground limits vertical mixing, trapping local pollutants clos e to the valley floor. Weak Pacific storms are prevalent; however, they often do not produce suffi cient mixing to improve air quality in this valley. Figure 6 shows the upper air temperatur e profiles from the Spokane Airport during one such inversion episode. The pollutant concentrations may build from day to day when the inversion does not break up in the afternoon, as shown on the right hand side of Figure 6. During epis odes such as this, emissions increase because more home heating is required due to the cold temperatures (Factor 1). The low sun angle at th is latitude, short length of the days during winter months, light and variable winds, and strong likelihood of snow cover to reflect solar radiation all limit atmospheric heating and aggravate the situation. As a result, the inversion builds and may not break for many days. Under this kind of stagna tion condition, pollutant co ncentrations may build quickly, especially in the areas like Pinehurst wh ere airflow is greatly restricted by terrain. When local emissions are high, even short-lived overnight inversions can affect air quality sufficiently to produce high pollutant concentratio ns. The main Coeur d’Alene River valley (to the west) is more open and bette r aligned with synoptic westerly windflow and, as a result, appears to be better ventilated. The windrose graph in Figure 7 shows the freque ncy of wind speed and wind direction in the Pinehurst area for a PM 2.5 stagnation episode from Decemb er 18 through December 22, 2006. The wind was light from the south for most of the time during this episode. The maximum 24-hour PM 2.5 concentration of 34.2 μ g/m 3 during this episode occurred on December 22, 2006. A similar wind pattern was observed for another PM 2.5 stagnation episode (January 2-5, 2006, shown in Figure 8). The maximum 24-hour PM 2.5 concentration of 21.1 μ g/m 3 occurred on January 5, 2006. These wind patte rns strongly suggest that under stagnation conditions, the exchange of air mass between Pinehurst and the other communities to th e east in the Silver Valley is very limited. The wind data also show that wind speed is generally low in Pinehurst year-round (Figures 9 and 10). Pollution roses (Fi gures 11 and 12) also show that the highestIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 16 PM 2.5 concentrations occur when winds are south- southeast. A northeastern flow can actually infiltrate this valley and improve air quality. The airflow and dispersion pattern s of the Pinehurst area were further analyzed by dispersion modeling. Modeling using the CALPUFF air quali ty dispersion model with 500-meter terrain resolution was conducted to simulate the episod es during January 3 – 4 and December 18 – 22, 2006. A low level hypothetical “source” (similar to a woodstove chimney) was located first in Pinehurst, then in other communities in the Silver Valley, to observe the predicted relative flow patterns during inversion conditi ons. Figure 13 shows the modeling results. The results show insignificant air exchange between Pinehurst and other towns in the main Silver Valley. For a hypothetical source located in Sme lterville, the predicted 24-hour relative concentration impact at the Pinehurst monitor is less than 0.1% of the impact in Smelterville itself and even lower when the source was located in the other towns in the Silver Valley more di stant from Pinehurst. When the hypothetical source was located in Pinehurst, the predicted 24-hour relative concentration impact in Smeltervi lle is less than 0.1% of the im pact in Pinehurst itself. All the information presented for these two factors demonstrates that Pinehur st is largely cut off from the Silver Valley airshed. The minimal pollu tant transfer behavior in the model runs is explained by the narrow gap in the terrain conne cting Pinehurst with th e Silver Valley. When stagnation occurs and cold air pools in Pinehurst, the cold air drains to the north, merging with the main Silver Valley drainage winds, ther eby blocking the main va lley flows from entering Pinehurst. The greatest contributing emissions source to PM 2.5 concentrations abov e the 24-hour standard that occurs consistently is re sidential wood heating between th e hours of 8 p.m. and 6 a.m. However, DEQ has recently gathered data, using a continuous monitor, which shows PM 2.5 concentrations greater than the 24-hour standard that have been directly linked to slash burning events. Such impacts have been reported to occur from slash burns on the ridges surrounding Pinehurst and neighboring valley fl oors when smoke rises toward the ridge facing away from Pinehurst, then apparently downw ashes on the lee side of the ri dge in Pinehurst, resulting in short-term peak concentrations. These short-term peak concentr ations (1 to 2 hours) can cause an excursion of the 24-hour sta ndard because the background concentration, due to residential wood heating, is typically already elevated wh en the slash burning impacts Pinehurst. Although slash burning is infrequent and the location and tim e of year is rarely constant, the realtime monitoring data indicate that slash burni ng can contribute to a violation of the PM 2.5 24-hour standard. These impacts suggest that the Pine Creek drainage , the nearest ridges immediately surrounding Pinehurst, and the nearest valley areas ju st beyond those ridges should be included in the NAA boundari es to address slash burning.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 17Figure 6. Temperature profiles measuredat the Spokane, Washington airport onDecember 20, 2006, at 5:00 a.m. (left) and5:00 p.m. (right).A deep inversion layer persisted in the area, which did not break up during the daytime. When this occurs, pollutants remaintrapped from day to day and the inversion builds.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 18 Figure 7. Windrose for Pinehurst, Idaho, December 18 – 22, 2006, the period of a PM 2.5 stagnation episode. Very few north and northeasterly winds occurred throughout the period. This indicates that there was very little air mass exchange be tween Pinehurst and the nearby towns in the Silver Valley.

Figure 8. Wind patterns during another winter PM 2.5 stagnation episode in Pinehurst, Idaho, January 2 – 5, 2006.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 19 Figure 9. Annual windrose for 2006, Pinehurst, Idaho. This shows that the wind speed in Pinehurst is generally low throughout the entire year. Winds rarely reach Pinehurst from the S ilver Valley to the north and northeast.

Figure 10. Windrose for Pinehurst, Idaho in the wintertime. Data from January, February, November, and December 2006.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 20 Figure 11. Pollution rose for Pinehurst, Idaho for wintertime: November 2005 – March 2006.

Figure 12. Pollution rose for Pinehurst, Idaho for wintertime: November 2006 – March 2007.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 21 Figure 13. Modeling results of hypothetical sources, showing that sources located in the Silver Valley do not contribute to a violation of the PM 2.5 standard in Pinehurst.

FACTOR 8: Jurisdictional boundaries (e.g., counties, air districts, reservations, etc.)
The town of Pinehurst is curren tly designated nonattainment for PM 10 . Figure 14 illustrates that the PM 10 NAA does not include locations within th e Silver Valley or surrounding counties. Shoshone County lies entirely w ithin DEQ’s Coeur d’Alene Re gion and EPA Region 10. The town of Pinehurst is also located in the Id aho/Montana Airshed Group, which implements the smoke management program for prescribed fire on both public and private lands.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 22 Figure 14. Pinehurst PM 10 nonattainment area.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 23 FACTOR 9: Level of control of emission sources As stated above, the town of Pinehurst is currently a PM 10 NAA, and specific voluntary controls have been implemented that partially pertain to PM 2.5 emissions. The major emissions sources of both PM 10 and PM 2.5 in Pinehurst are residential wood heating and open burning. DEQ implements a daily air quality advisory program for woodstove and open burning from November 1 through March 31 of each year. Open burning and slash burning in the fall is currently controlled by DEQ burn bans issued based upon ventilation predictive models. The Montana/Idaho Airshed Group also participates in burning rest rictions during October and November. Proposed geographic boundaries for the Pinehurst NAA Shoshone County is considered rural, and the main emissions sources that occur in the town of Pinehurst are residential wood h eating and vehicles. However, open burning and slash burning is a large emissions source that can cont ribute to a viola tion of the 24-hour PM 2.5 standard. The location and time of occurrence of slash burning and open burning vary from year to year. Slash burning can occur on all state a nd privately owned land that surrounds the town of Pinehurst. Analysis of the Pinehurst area shows that t opographical features a nd wintertime meteorology limit transport of pollutants between the Silver Va lley and Pinehurst. Poll utants emitted within Pinehurst remain trapped, and emissions from the Silver Valley do not contribute to PM 2.5 pollutant concentrations. Due to topographical features, seasonal wintertime meteorology, a nd types of emission sources, DEQ determined that the appropriate boundary for the PM 2.5 nonattainment area extends beyond the current PM 10 NAA boundary. This expanded area includ es those areas where, if slash burning occurs, it could contribute to a violation of the 24-hour PM 2.5 standard. DEQ’s proposed geographic boundary for the Pinehurst PM 2.5 NAA is shown in Figure 15.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 24 Figure 15. Proposed geographic boundary for the Pinehurst PM 2.5 nonattainment area.
4.2 Franklin County – Cache Valley Nonattainment Area Boundaries The Cache Valley straddles the Utah-Idaho borde r, extending into both Cache County, Utah and Franklin County, Idaho (Figure 16). The C ache Valley is a bowl-shaped valley measuring approximately 60 kilometers north to south and 20 kilometers east to west. The Wellsville Mountains lie to the west, and on the east lie the Bear River Mountai ns; both are northern branches of the Wasatch Range. The Idaho portion of the valley is rela tively flat, traversed by the Bear River, and dotted with small farm towns in the west and the larger towns of Preston and Franklin in the east along the benche s of the Bear River Mountains.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 25 Figure 16. Location map showing the Cache Valley and the boundaries of Franklin County, Idaho and Cache County, Utah.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 26 FACTOR 1: Emissions in areas potent ially included vs. excluded from the NAA DEQ gathered emissions information for Frankl in County and the bordering counties in Idaho. Utah will provide the information necessary for their adjacent counties and that portion of the proposed PM 2.5 NAA when they submit their recommendations.
The main sources of emissions dur ing winter in Franklin County ar e vehicles (tailpipe emissions and fugitive road dust), residential wood heating, and agriculture (feedlo t and dairy ammonia). With the exception of the ruminant animal em issions, emissions created in Franklin County during winter are population-based. All major industrial point sour ces located in Idaho are more than 60 to 90 kilometers from the Cache Valley. Table 8 presents direct PM 2.5 emissions, as well as the pollutants that can act as PM 2.5 precursors. Because elevated PM 2.5 concentrations in the Cache Va lley are a wintertime phenomenon that threaten only the 24-hour PM 2.5 standard (Factors 6 and 7), pres cribed and wild fire emissions occurring in the other seasons were not included in Table 8. Table 8. Annual emissions after prescribed and wild fire emissions are deducted.

COUNTY SOx (TPY) NOx (TPY) NH3 (TPY) VOC (TPY) PM 2.5 (TPY)
Franklin 57 851 1221 2290 447
Bannock 177 4020 683 7178 1343
Bear Lake 34 2103 361 2380 359
Caribou 12623 2452 1221 2454 1536
Oneida 40 509 325 1409 243 Source: http://www.epa.gov/ttn/naaqs /pm/pm25_2006_techinfo.html (2005 NEI) SO x– oxides of sulphur; NO x– oxides of nitrogen; NH 3 – ammonia; VOC – volatile organic compound; PM 2.5 – particulate matter with an aerodynamic diameter of 2.5 micrometers or less; TPY – tons per year

Factor 2: Air quality in areas potent ially included vs. excluded from the NAA Air quality data have indicated that Cache Valley violates the 24-hour PM 2.5 standard. In fact, the 24-hour design value for Logan, Utah is by fa r the highest of any station within Utah’s monitoring network. DEQ collected PM 2.5 data in the Idaho portion of the Cach e Valley. There is not yet a three-year data set to determine compliance with the PM 2.5 standard, but indications are that once the data is available, it will also indicate a violation of the 24-hour standard in the Idaho portion (Figure 2). DEQ established monitors in both Franklin and Preston, Idaho in 2004. These monitors confirmed results of the Utah State University PM 2.5 saturation study conducted by Dr. Randy Martin (2006), which indicated a fairly homogenous air mass throughout the Cache ValleyIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 27 during inversions. The monitor in Preston has b een removed due to its high correlation with the Franklin monitor, but DEQ continues to operate the Franklin monitor. Factor 3: Population density and the degree of urbanization, including commercial development, in areas potentially included vs. excluded from the NAA Franklin County and the Cache Valley are part of the Logan core based st atistical area (CBSA) according to EPA's 2005 national emissions inve ntory (NEI) data on their TTN Web site. The Idaho portion of the Cache Valley lies entirely within Franklin County. The majority of the population of this rural county is located in sm all towns. The two largest Idaho towns in the Cache Valley are Preston, with a 2006 population of 5,089, and Fr anklin, with 672 residents. The remainder of Franklin County and the surrounding counties have low populations and, therefore, low population densitie s. The one exception is Bannock County, home to the city of Pocatello (2006 population of 53,932). Pocatello is approximately 95 kilometers to the northnorthwest and also represents the commercial ce nter for southeastern Idaho. There is little industrial or commercial developmen t in Franklin County (Factor 1). Table 9 presents the population, county size, and population density for Franklin County and bordering counties within Idaho. Utah will provide th e county information for their portion of the Cache Valley. A graphical representation of the population density in the Cache Valley is shown in Figure 17. Table 9. 2006 population densities for Fr anklin County and adjacent counties.

County 2006 Population County Size (km 2 ) 2006 Population Density (residents per km 2 ) Franklin 12,494 1723.6 7 Bannock 78,443 2883.2 27 Bear Lake 6,167 2516 2 Caribou 6,996 4574.2 2 Oneida 4,176 3109.1 1
Sources: http://www.census.gov/popest/counties/CO-EST2006-03.html for 2006 populations; http://www.census.gov/population/censusdata/90den_stco.txt for size.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 28 Figure 17. Population density for the Cache Valley ( http://sedac.ciesin.columbia.edu:9080/entri/index.jsp ; accessed July 1, 2007).Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 29 Factor 4: Traffic and commuting patterns Commuting information from the EPA TTN 2006 PM 2.5 technical data:

• Franklin County, the county of intere st, has a total of 4,838 commuters.

- Commuters who remain in Franklin County: 2,852

- Commuters from Franklin Count y to Cache County, Utah: 1,697

- Commuters from Franklin County to Bannock County: 19

- Commuters from Franklin County to Caribou County: 92

- Commuters from Franklin C ounty to Oneida County: 6

- Commuters from Franklin Count y to Box Elder County, Utah: 82

- Commuters from Franklin C ounty to Rich County, Utah: 1

• Bannock County, an adjacent county, has a total of 35,122 commuters.

- Commuters who remain Bannock County: 30,566

- Commuters from Bannock Count y to Franklin County: 70

- Commuters from Bannock Count y to Cache County, Utah: 42

• Bear Lake County, an adjacent county, has a total of 2,443commuters.

- Commuters who remain in Bear Lake County: 1,823

- Commuters from Bear Lake C ounty to Franklin County: 2

- Commuters Bear Lake Count y to Cache County, Utah: 26

• Caribou County, an adjacent county, has a total of 2,944 commuters.

- Commuters who remain in Caribou County: 2,622

- Commuters from Caribou Count y to Franklin County: 34

- Commuters from Caribou Count y to Cache County Utah: 38

• Oneida County, an adjacent count y, has a total of 1739 commuters.

- Commuters who remain in Oneida County: 1,127

- Commuters from Oneida Count y to Franklin County: 8

- Commuters from Oneida Count y to Cache County, Utah: 34

• Box Elder County, Utah, an adjacent county, has a total of 18,030 commuters.

- Commuters who remain in Box Elder County: 13,570

- Commuters from Box Elder County, Utah to Franklin County: 0

- Commuters Box Elder County, Ut ah to Cache County, Utah: 631Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 30 • Cache County, Utah, the county of inte rest, has a total of 43,731 commuters.

- Commuters who remain in Cache County: 39,235

- Commuters from Cache County, Ut ah to Franklin County: 179

• Rich County, Utah, an adjacent county, has a total of 717 commuters.

- Commuters who remain in Rich County: 512

- Commuters from Rich County, Ut ah to Franklin County: 2

- Commuters Rich County, Utah to Cache County, Utah: 41
The commuter information above indicates that ve ry few commuters enter Franklin County from counties other than Cache County, Utah. Severa l counties surrounding Franklin County have substantially higher annual VMT (Table 10). Franklin County accounts for approximately 17% of the total VMT in the Cach e Valley (Franklin County and C ache County, Utah). The major roadways located in the Cache Valley are shown in Figure 18. Table 10. Annual VMT (vehicle miles traveled) for Franklin County and adjacent counties in both Idaho and Utah.

County VMT (Millions)
Franklin 189.8723
Bannock 474.2377
Bear Lake 104.2817
Caribou 118.9588
Oneida 68.1813 Box Elder (Utah) 782.6866 Cache (Utah) 935.9099 Rich (Utah) 34.0305 Source: EPA TTN 2005_vmt_county_level-1.xlsIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 31 Figure 18. Roadways in the Cache Valley.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 32 FACTOR 5: Expected growth (including extent, pattern, and rate of growth) The Idaho portion of the Cache Valley is not a highly populated area (Factor 3). From 2000 to 2006, the Idaho side of the Cache Valley experien ced a 10.3% increase in population, to a total of 12,494 persons, while the Utah side of th e Cache Valley, which is more urbanized, experienced an 8% increase in populati on, to a total of 98,661 (Table 11). Table 11. Population growth in the Cache Valley from 2000 to 2006

State City April 2000 July 2006 P opulation change Percent Change Idaho Franklin County 11,329 12,494 1165 10.3% Utah Cache County 91,391 98,661 7271 8.0% Cache Valley NAA (nonattainment area) 102,720 111,155 8435 8.2%

The annual population estimates for Franklin Co unty, including the annual percent change, from 2000 through 2006, are presente d in Table 12.
Table 12. Population growth in Franklin County, Idaho from 2000 through 2006

Year Population Estimates Population Difference Percent Change (%) 2000 11,329 __ __ 2001 11,500 171 1.5 2002 11,802 302 2.6 2003 11,846 44 0.37 2004 12,160 314 2.7 2005 12,410 250 2.1 2006 12,494 84 0.68

FACTOR 6: Meteorology (wea ther/transport patterns) AND FACTOR 7: Geography/topography (mountain ranges or other air basin boundaries) Factors 6 and 7 are discussed together because they are thoroughly interrelated. The mountains surrounding the Cach e Valley rise to 8,356 feet above sea level (asl) to the west and 9,900 feet (asl) to the east. The isolated valley floor ranges from 4,500 to 5,200 feet (asl). The mountains trap pollutants in the valle y when dispersion conditions are poor.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 33 The Cache Valley experiences air stagnation events in the wintertime. Du ring these periods, the stable layer above the ground is much deeper th an a typical nocturnal inversion. Cold air is trapped in the basins, and the air mass stabilizes as high pressu re aloft overtakes the region. Under such circumstances, a pr olonged strong inversion layer (o r layers) limits the vertical mixing, trapping local pollutants in a thin layer ag ainst the valley floor. During episodes such as this, emissions increase because more home heating occurs due to the cold temperatures (Factor 1). The low sun angle, short length of the days during winter months, and strong likelihood of snow cover to reflect the solar radiation are all f actors that limit daytime surface heating and aggravate the situati on. As a result, some inversions may not break for many days. A study of deep stable layers (DSLs) in west ern air basins (Wolyn and McKee, 1989) revealed that DSLs can cause the stagnation of cold air in basins. In other words, only light winds occur at the surface, even if moderate ly strong winds aloft are present, and restriction of the growth of daytime convective boundary layers occurs. DE Q analyzed DSLs in the Treasure Valley and found high correlation between DSLs and particulate levels in the area. Sa lt Lake City was found to have a high frequency of DSL occurrence, aver aging about 12 days per year in the period from 1959-1983 (Wolyn and McKee, 1989). The Cache Valley is most likely under the same stagnation conditions as the Salt Lake City area during most of these periods. Figure 19, which is from a Utah State University inversion study (Martin, 2006), provides an excellent example of correlation between the PM 2.5 concentration levels and the evol ution of the stable layer over the Cache Valley. In Figure 19, blue represents cold air and red indicates warmer air. The solid yellow line represents the ambient PM 2.5 concentration as measured at the Logan monitoring site. The dotted green line represents the 1997 PM 2.5 NAAQS. From January 9 through January 17, 2004, the cold air pool strengthened and deepened each day, eventually reaching a depth of about 5,500 feet (asl) on January 15 when the PM 2.5 concentrations peaked. The PM 2.5 concentration levels rose steadily as trapped pollutants accumulated from each day to the next. Under this type of stagnation c ondition, the pollutants may quickly build, especially in areas like the Cache Valley where airflow is greatly restri cted by terrain. Figure 20, also taken from the Utah State University inversion study (Mar tin, 2006), provides an example of inverted temperature profiles in the Cache Valley duri ng the January 2004 extended stagnation episode. During the period from January 1 to January 17, 2004, as shown in the figure, a strong inversion about 1,500 feet thick persis tently occupied the area. The record high PM 2.5 concentration of 132.7μg/m 3 was observed at Logan on January 15, 2004. The strong, deep, stable layer persisted through the entire period, even in the afternoon hours (12 noon a nd 3 pm) when the base of the inversion rose to an average 5,500 f eet (asl). The average 24-hour PM 2.5 concentration observed at the Franklin monitor during this same period was 39.0 μg/m 3 , with the highest 24-hour concentration of 82.6 μg/m 3 occurring on January 17, 2005. Thus, it appears that the afternoon mixing height during stagnation episodes (at appr oximately 5,500 feet asl) is the controlling factor in accumulating pollutants from day to day.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 34 Figure 19. January 2004 temperature contour map with PM 2.5 concentration (yellow) and 1997 PM 2.5 National Ambient Air Quality St andard (green) (Martin, 2006)

Figure 20. Average temperature profiles in Cache Valley during January 1 - 17, 2004 (Martin, 2006)Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 35 Factor 8: Jurisdictional boundaries (e.g., co unties, air districts, reservations, etc.)
Given the nature of PM 2.5 as a regional rather than a loca lized pollutant, DEQ recommends the Cache Valley PM 2.5 NAA extend from Cache County, Utah into Franklin County, Idaho. This NAA will span two states and two different EP A regions – Utah, EPA region 8 and Idaho, EPA Region 10. For transportation planning purposes, both Frankl in County, Idaho and Cache County, Utah are part of the Logan MSA. The Logan MSA is complicated, since a metropolitan planning organization (MPO) exists on the more urban Utah side and not on the Idaho side. Idaho is committed to work with all stakeholders to determine the best approach to comply with transportation conformity. Maintaining separate nonattainment areas allows each state to develop strategies to reduce PM 2.5 pollution that are most appropriate to each area and to implement processes that recognize the regulatory, political, and financia l realities specific to the two counties and two states. Idaho DEQ and Utah DEQ are committed to working c ooperatively to ensure their air quality improvement plans are integrat ed and mutually supportive. Factor 9: Level of control of emission sources As discussed in Factor 1, there are no major i ndustrial sources in Fra nklin County; therefore, emissions in the Idaho portion of the Cache Valley are from vehicles (tailpipe and fugitive road dust), residential wood heating, a nd agriculture (feedlot and dair y ammonia). DEQ is beginning to evaluate emission reduction cont rols for woodstoves and vehicles. Proposed geographic boundaries for the Franklin County – Cache Valley Nonattainment Area Analysis of the Cache Valley, specifically the Id aho portion, shows that to pographical features and wintertime meteorology limit the transport of pollutants into or out of the Cache Valley. Pollutants emitted within the Cache Valley (Utah and Idaho) remain trapped, and emissions from surrounding Idaho counties do not impact the PM 2.5 monitor located in Franklin, Idaho. The Cache Valley experiences inversions that bu ild from day to day when strong high-pressure systems are present in the regi on. The average afternoon mixing he ight during stagnation events is about 5,500 feet (asl). Ther efore, any areas in Franklin Co unty that are higher than 5,500 feet (asl) in elevation wi ll not contribute to PM 2.5 concentrations during wintertime inversions. However, not all areas below 5,500 feet (asl) are a ppropriate to be included in the nonattainment area. Only those areas with significant em issions and population shoul d be included. The population in Franklin County is clustered in the to wns, with the majority located in Preston and Franklin. The townships identified in Figure 21 are those that account for the higher population density and, therefore, emissions. These townsh ips delineate those portions of Franklin County that are appropriate to include in the Franklin County – Cache Valley PM 2.5 nonattainment area.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 36 Figure 21. Proposed geographic boundaries for the Idaho portion (Franklin County) of the proposed Cache Valley PM 2.5 nonattainment area.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 37 

### 5. Summary The State of Idaho recommends only two areas in Idaho for nonattainment designation. Figures 15 (page 24) and 21 (page 36) provide graphical representations of the townships Idaho is recommending to be included in the Pinehurst and Franklin County – Cache Valley NAAs, respectively. Table 13 (Appendix A) provides th e legal description of all areas of the State and the designations Idaho is recommending for the PM 2.5 standard. 

### 6. References Wolyn, P. G., and T. B. McKee, 1989: Deep Stab le Layers in the Intermountain Western United States. Monthly Weather Review , 117, 461–472. Martin, Randy, 2006. Cache Valley Air Qualit y Studies; a Summary of Research Conducted (through 2006). Department of Civil & Environm ental Engineering, Utah State University.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 38Appendix A – All Designated andNon-Designated Area DescriptionsIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 39Table 13. Descriptions of all areasof the state and the designationsCounty Attainment Unclassifiable NonattainmentNonattainmentArea NameShoshone All portions ofShoshoneCounty nototherwisedesignatednonattainmentAll portions of Shoshone Countylocated in the followingtownship/range/sections:T R S QQ49N 02E 3148N 02E 648N 02E 548N 01E 1248N 02E 748N 02E 848N 02E 948N 01E 1348N 02E 1848N 02E 1748N 02E 1648N 01E 2448M 02E 19PinehurstIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 40County Attainment Unclassifiable NonattainmentNonattainmentArea Name48N 01E 1 NENW NESWNWNE NWSENENE NESESWNW SWSWSENW SESWSWNE SWSESENE SESENWSW48N 01E 11 SESE SWSE48N 01E 14 NENE NWSENWNE NESESWNE SWSESENE SESEIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 41County Attainment Unclassifiable NonattainmentNonattainmentArea Name48N 01E 22 SENE NESE48N 01E 23 NENW NWSWNWNE NESWNENE NWSESWNW NESESENW SESWSWNE SWSESENE SESE48N 01E 25 NWNW SWNWNENW SENWNWNE SWNENENE SENE48N 01E 26 SWNE NWNESENE NENEIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 42County Attainment Unclassifiable NonattainmentNonattainmentArea Name48N 02E 4 NWNW NWSWSENW SWSWNESW SESWNWSE SWSESWNW SESE48N 02E 10 SWSW48N 02E 15 NWNW NWSWNENW NESWSWNW SWSWSENW SESW48N 02E 20 NWNW SENWNENW SWNENWNE NWSWIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 43County Attainment Unclassifiable NonattainmentNonattainmentArea NameNENE NESWSWNW SWSW48N 02E 21 NWNE NENE48N 02E 22 NWNW NENW48N 02E 29 NWNW SWNW48N 02E 30 NWNW SWNWNENW SENWNWNE SWNENENE SENE49N 01E 25 SESE49N 01E 36 NENE NESEIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 44County Attainment Unclassifiable NonattainmentNonattainmentArea NameSWNE SESWSENE SWSENWSE SESE49N 02E 30 SWNW NWSWSENW NESENESW SWSWNWSE SESWSWNE SWSESENE SESE49N 02E 32 NWNW NWSESWNW NESESENW SWSWSWNE SESWSENE SWSENWSW SESEIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 45County Attainment Unclassifiable NonattainmentNonattainmentArea NameNESW49N 02E 33 SWSWFranklin All portions ofFranklinCounty nototherwisedesignatednonattainmentAll portions of Franklin County locatedin the following townships:15 south 39 east16 south 38 east16 south 39 east16 south 40 eastFranklin –Cache ValleyAdaCanyonBannockBenewahAll portionsof therespectivecountyexcept forTribalLandsBear LakeBinghamBlaineJeffersonJeromeKootenaiAll portions ofthe respectiveCounty exceptfor TribalLandsIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 46County Attainment Unclassifiable NonattainmentNonattainmentArea NameBoiseBonnerBonnevilleBoundaryButteCamasCaribouCassiaClarkClearwaterCusterElmoreFremontGemGoodingIdahoLatahLemhiLewisLincolnMadisonMinidokaNez PerceOneidaOwyheePayettePowerTetonTwin FallsValleyWashingtonIdaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 47 

### Appendix B – Supporting Documentation Locations Supporting Documentation (from the EPA Holmstead memo of 2003) The supporting information needed for nonattainment areas can be found in this document as follows:

• PM 2.5 design value(s) for the area: See Tables 1 and 2

• The 3-yr period represente d by the design value: See Section 3

• Site locations and ID numbers: See Table 14

Table 14. Monitor locations and ID numbers for PM 2.5 nonattainment areas Site ID Location Address County 16-079-0017 Pinehurst Elementary School S. 201 Third St. Shoshone 16-041-0001 Franklin Water Treatment Facility East 4800 South Franklin

The supporting information needed for attainme nt/unclassifiable AND no nattainment areas are as follows:

• Names of counties and tr ibal lands included: See Table 13

• If partial counties or portions of tribal lands are included, the boundary definition/description

o Legal definition: See Table 13

o hard copy map: See Figures 15 and 21

o digitized lat/long description: will be transmitted upon request

o Explanation of how the boundary is cons istent with Sect. 107(d)(1) of the CAA: Paragraph A of Section 107(d)(1) of the Clean Air Act describes the three designations an area may carry. Idaho’s recommendations are consistent with the definitions provided therein. The areas recommended for designation of “nonattainment” are areas represented by monitored ambient ai r data that does not meet the primary (or secondary) 24-hour standard for PM 2.5 . The surrounding areas were evaluated, using the EP A-recommended nine-factor analysis, to determine whether they were impacting the nonattainment areas.Idaho Area Designation Recommendations for the 2006 PM2.5 NAAQS 48 The areas recommended for designation of “attainment” are represented by monitored ambient air data that does meet all the primary and secondary standards for PM 2.5 . The areas recommended for designation of “unclassifiable” are areas for which there is insufficient da ta to draw any conclusions.

Names of Contacts

Martin Bauer Administrator, Idaho Air Quality Division (208) 373-0552

Robert Wilkosz Manager, Mobile and Area Source Program (208) 373-0302

Bruce Louks Manager, Monitoring, Modeling, and Emission Inventory Program (208) 373-0294