Attachment 2 

D-1 

Appendix D 

Emission Inventory Methodology 

Agricultural Irrigation Pumps - Diesel

(Updated August 2006)

INTRODUCTION 

Diesel-fueled agricultural irrigation pump engines are a significant source of 

emissions in California, especially during the April through October growing season. 

The Air Resources Board (ARB) estimates that in 2005, diesel-powered agricultural 

irrigation pump engines were the 8th largest source of nitrogen oxides and the 21st

largest source of fine particulate matter in the San Joaquin Valley. For the 

Sacramento Valley, irrigation pump engines are the 10th largest source of nitrogen 

oxides and the 22nd largest source of fine particulate matter. 

Irrigation pumps are used to pump water from either wells or supply canals to the 

field. They are also used for a number of other purposes, such as discharging water 

from tailwater pits, ponds, lakes, etc. Booster pumps are used to increase the water 

pressure for water that has already been removed from the source by another pump. 

Pump engines can be either stationary or portable. A stationary pump engine is 

fixed in place; a portable pump engine is one that is mounted on a mobile piece of 

equipment or on skids and is moved from place to place depending on the need. 

Both well pumps and booster pump engines can be either portable or stationary. 

METHODS AND SOURCES

Emissions from the irrigation pump engines are estimated by multiplying the number 

of pump engines by their horsepower rating, load factor, annual operating hours, and 

emission factor. 

The basic equation for calculating the emission of agricultural irrigation pump 

engines is: 

E y = Σ Pop ∗ EF∗ Hrs ∗ HP ∗ %Load 

EMISSION INVENTORY SOURCE CATEGORY

 Fuel Combustion / Food and Agricultural Processing 

EMISSION INVENTORY CODES (CES CODES) AND DESCRIPTION

 052-042-1200-0000 Agricultural Irrigation I.C. Engines – Diesel/Distillate 

 
D-2 

 where 

E = pollutant specific emissions (tons per year of NOx, HC, CO2, and 

diesel PM) 

 y = inventory year 

 Pop = population of diesel agricultural irrigation pump engines 

 EF = emission factor (units of g/bhp-hr) 

 Hrs = average annual use in hours 

 HP = average brake horsepower of engine 

 %Load = average engine load factor 

Population 

The 2003 US Department of Agriculture Farm and Ranch Irrigation Survey (FRIS) 

(reference 1) stated that there are 83,216 electric or fuel-powered irrigation pumps in 

California, of which 12,535 (or approximately 14.1 percent) are powered with diesel 

engines. Assuming that well and booster pump engines are powered by the various 

fuels at the same relative amounts as the general pump engine population, 8,721 of 

the 12,535 diesel engine pumps are well pumps and the remaining 3,814 pumps are 

booster pumps, performing such tasks as discharging water from tailwater pits. 

For inventory purposes, it is necessary to allocate pump engine populations among 

the various counties, air basins, and districts of California. This is normally done by 

one of two methods: the bottom-up method uses databases of individual pump 

locations to determine where in the state pumps are located; and the top-down 

method takes a statewide total and uses a surrogate (such as the amount of irrigated 

acres in a given area) to estimate the pump population in that area. The bottom-up 

method is usually preferred, but requires extensive databases that are often not 

available. The top-down method is less specific, but is a more straightforward 

calculation. 

Because of the limited amount of data on individual pump locations, this 

methodology uses a hybrid approach and uses both bottom-up and top-down 

methods to allocate pumps (and therefore pump engines) statewide. To the extent 

possible, district data was used to allocate the number of stationary and portable 

pump engines to specific areas of the state. Where district data was not available or 

lacking in specificity, top-down estimates were made of pump engine locations. 

Bottom-Up Inventories Used 

A database of well and lift pump engines in the Sacramento Ozone Non Attainment 

area (reference 2) shows 1,032 pump engines in that area; Sacramento Metropolitan 

AQMD staff estimate an additional 132 pump engines (both stationary and portable) 

that were not surveyed. The Sacramento Non-Attainment area includes all of 

Sacramento, Solano, Yolo, and Yuba Counties, and portions of Placer and Sutter 

Counties. In total, it is estimated that there are 1,164 diesel irrigation pump engines 

in the Sacramento Non-attainment area. The 132 additional pump engines 
D-3 

estimated by Sacramento Metro AQMD staff were assigned to counties within the 

non-attainment area using the top-down methods described below. 

The South Coast AQMD surveyed farm operators in their district in January 2005 

and again in 2006 to determine the number and size of irrigation pump engines. 

Results of these surveys demonstrated that that there are 12 portable and 

6 stationary diesel pump engines in the South Coast Air Basin (reference 3). For the 

purposes of this inventory, the portable engines were assumed to be booster pump 

engines and the stationary pump engines were assumed to be on well pumps. 

Because the survey did not include information on the specific county engines were 

located in, they were attributed to the counties in the South Coast Air Basin by 

top-down methods as described below. 

Top-Down Inventories Used 

Top-down methods were used to allocate pump engine populations to all remaining 

areas of the state. Surrogates to allocate well pump engines and booster pump 

engine populations were developed using 2000 U.S. Geological Survey (USGS) data 

on the amount of ground and surface water withdrawals (reference 4). Ground water 

withdrawals were used to allocate well pump engine populations. USGS data on the 

amount of surface water withdrawals for agriculture was used to allocate booster 

pump engines by county. Because some surface water irrigation is done by gravity 

and thus does not require any pumping of any kind (for example, in rice fields), the 

amount of surface water withdrawals was multiplied by the ratio of sprinkler and drip 

irrigation acreage to total acreage irrigated by sprinkler, drip, and surface irrigation to 

estimate the potential gravity irrigation for a given county. Data on irrigation acreage 

by type was obtained from USGS (reference 4). Although surface irrigation can be 

accomplished by either gravity or pumping, no comprehensive regional data was 

available to estimate the proportion of surface irrigation that is pumped. 

For counties split between air basins or non-attainment areas, GIS data on irrigated 

acreage developed by the California Department of Water Resources (reference 5) 

was used to estimate the proportions of pump engines in the split portions of a 

county. 

All 18 estimated pump engines in the South Coast Air Basin and the 132 additional 

engines in the Sacramento Non-Attainment Area were allocated to counties within 

the respective regions using the surrogates described above. 

Estimation of the split of stationary and portable pump engines by county was done 

based upon a methodology developed by Booz-Allen & Hamilton for the OFFROAD 

model (reference 6). This methodology was based upon interviews with engine 

manufacturers (DDC, Caterpillar, Cummins, and Deutz) and equipment 

manufacturers (Stewart & Stevenson and Valley Diesel) which suggested that the 

majority of generator, pump, and compressor engines greater than 100 horsepower 

were stationary. Table D-1 defines the percentages of portable and stationary 

engines by horsepower that were developed as a result of this work. 
D-4 

Table D-1 – Portable vs. Stationary 

Engine Distribution 

Horsepower 

Rating 

Percent 

Portable 

Percent 

Stationary 

0-25 100% 0% 

26-50 90 10 

51-120 70 30 

121-175 20 80 

176-250 15 85 

251-500 10 90 

501-750 10 90 

>750 10 90 

Table D-2 (on Page D-5) summarizes the resulting pump engines population used 

for the emissions estimates. 
D-5 

Table D-2 – Estimated 2003 Diesel Agricultural Irrigation 

Pump Engine Population 

District Portable Stationary Total 

Amador County APCD 5 12 17

Antelope Valley APCD 2 17 19

Bay Area AQMD 49 98 147

Butte County AQMD 183 304 487

Calaveras County AQMD 1 3 4

Colusa County APCD 98 228 327

El Dorado County APCD 4 7 11

Feather River AQMD 214 315 529

Glenn County APCD 109 177 286

Great Basin Unified APCD 46 102 148

Imperial County APCD 46 69 115

Kern County APCD 4 11 15

Lake County AQMD 7 21 28

Lassen County APCD 48 121 169

Mariposa County APCD 0 1 1

Mendocino County AQMD 8 16 24

Modoc County APCD 35 72 107

Mojave Desert AQMD 0 2 2

Monterey Bay Unified APCD 161 513 674

North Coast Unified APCD 20 45 64

Northern Sierra AQMD 19 31 50

Northern Sonoma County APCD 7 12 20

Placer County APCD 27 34 61

Sacramento Metropolitan AQMD 35 65 101

San Diego County APCD 74 104 178

San Joaquin Valley Unified APCD 2092 4965 7057

San Luis Obispo County APCD 32 92 124

Santa Barbara County APCD 75 165 241

Shasta County AQMD 33 81 114

Siskiyou County APCD 87 161 248

South Coast AQMD 12 6 18

Tehama County APCD 60 135 195

Tuolumne County APCD 1 2 3

Ventura County APCD 44 100 145

Yolo/Solano AQMD 238 570 808

Statewide 3879 8656 12535

Horsepower Distribution 

Where available, district data was used to define pump engine horsepower. 

Information on horsepower ratings of 1,032 engines from the Sacramento 

Non-Attainment Area and South Coast AQMD was used to allocate pump engines 
D-6 

for these areas. Also, Carl Moyer Program data for approximately 1,300 pump 

engines replaced between 1997 and 2003 was used to estimate emissions for 

engines in the Sacramento, San Joaquin, and Monterey Unified local air district 

jurisdictions. 

To estimate the horsepower of pump engine populations across the state where no 

specific information was available, the minimum horsepower required to move water 

for irrigation was calculated. Where engine specific horsepower was available, 

comparisons were made between actual engine horsepower data and the estimated 

horsepower to ensure that the estimated horsepower profiles were reasonable 

estimates. 

Three equations define the brake horsepower required to pump a given amount of 

water: 

Equation 1: 

TDH= SH + FH +VH + PH

Where: 

TDH = Total Dynamic Head (feet) 

SH = Total Static Head (feet) (total vertical distance pump must lift water) 

FH = Friction Head (feet) (pressure head loss due to friction in pipes) 

VH = Velocity Head (feet) (energy imparted to water to get it in motion; usually negligible) 

PH = Pressure Head (feet) (pressure required to operate the irrigation system) 

(1 foot of pressure = 2.31 pounds per square inch) 

Equation 2: 

WHP = Q *TDH / 3960

Where: 

WHP = Water Horse Power 

Q = Flow Rate in gallons per minute 

TDH = Total Dynamic Head (feet; from equation 1)) 

Equation 3: 

BHP = WHP /(PE *DE * LF * DRE)

Where: 

BHP = Brake Horsepower 

WHP = Water Horsepower (from equation 2) 

PE = Pump Efficiency (percent) 

DE = Drive Efficiency (percent) 

LF = Load Factor 

DRE = Relative Efficiency of Diesel Engines compared to Electric Motors 

Well Pumps 

The total static head for well pumps is the depth to water for a well plus the drawdown 

(the lowering of the water table as a result of the pumped water). The average depth 

to water was obtained from USGS for over 10,000 wells in California (reference 7). A 

drawdown of 50 feet was assumed for wells with water depths of less than 500 feet; a 

drawdown of 100 feet was assumed for deeper wells. The depth of pump drawdowns 

can vary from well to well based on location and quality of the well. In general the 

drawdown of a well should be negligible. However, in practice the distance can 

change because of seasonal rain fall or pumping at a rate that exceed the ability of the 
D-7 

well to refresh itself. Therefore, the maximum drawdown is the distance between the 

initial water level and the top of the pump bowls formed by the water pumping. To 

compensate for this change in static head a minimum distance between the water level 

and the pump bowl is assumed to range from 50 to 100 feet depending on the depth of 

the well. 

Well locations were determined with GIS software, and only wells located within 

irrigated agricultural fields (as defined in the Department of Water Resources land use 

data set found in reference 5) were used to determine horsepower. Because the 

USGS well database contains information on specific wells at specific locations, these 

data were used to determine horsepower profiles specific to each county, air basin, 

and district. 

Because pumps are purchased to accomplish a wide variety of tasks, a pressure 

head of 75 pounds per square inch (psi) was assumed as an upper bound of typical 

operating pressures. This pressure would be typical of that found in a booster pump 

that lifts the water an additional 10 feet once the water has reached the surface and 

pressurizes a sprinkler system such as rainmakers. 

Table D-3 lists the parameters used to calculate horsepower profiles for well pump 

engines. Data on flow rates and the static head of booster pumps were obtained from 

the 2003 FRIS (reference 1). Friction head was estimated at 2.54 feet, based on data 

contained in publication by the National Resources Conservation Service 

(reference 8), which represents the friction imparted by a flow rate of 900 gallons per 

minute through 100 feet of steel 8-inch diameter pipe. This value was selected as a 

mid-range estimate of friction loss. Friction head varies with the length of irrigation 

pipe, flow rate, and the diameter of pipe and can range between near zero to well over 

20 feet for high flow rates and lengthy pipes. 

Table D-3 – Parameters Used to Calculate Horsepower of 

Irrigation Pump Engines 

Booster Pumps 

Parameter Well Pump 

Tailwater 

Pump 

Pond/Lake 

Discharge Relift 

Static Head 

Average Depth to 

Water 11 20 19 

Friction Head 

(feet) 2.54 2.54 2.54 2.54 

Pressure Head 

(psi) 75 75 75 75 

Flow Rate (gpm) 802 450-4937 450-4376 

450-

5277 

Pump Efficiency 86% 80% 80% 80% 

Drive Efficiency 85% 95% 95% 95% 
D-8 

The pump efficiency can vary between 70 and 90 percent depending on the type, size, 

and number of stages. A pump efficiency of 86 percent was assumed for these 

calculations. The drive efficiency is the efficiency of the drive between the engine and 

the pump itself; it varies between 70 percent and 100 percent depending on the 

method used to connect the motor and the pump. For these calculations, a drive 

efficiency of 85 percent was used. The relative efficiency of diesel engines compared 

to electric motors is about 75 percent; that is, an electric motor needs to be only 

75 percent as powerful as a diesel engine to perform the same amount of work. 

Table D-4 lists the average estimated horsepower and the range of horsepower used 

to calculate emissions. This data was used only when districts did not provide specific 

data. The bottom-up data for the Sacramento Non-Attainment Area has an average 

horsepower of 147 hp for well pump engines, which compares favorably with the 

149 hp/157 hp estimates for engines in the Yolo/Solano AQMD and the Sacramento 

Metro AQMD local air districts. The average horsepower of the engines replaced 

under the Carl Moyer Program for the San Joaquin Valley is 197 hp, which is very 

close to the 196 hp estimate in Table D-4 for the San Joaquin Unified APCD. In 1996, 

Sonoma Technology (reference 9) surveyed San Joaquin Valley farmers on their 

irrigation pumps and showed an average horsepower of 161 hp for diesel engines. 

However, this average was based on only 35 responses out of 368 qualified 

respondents. 

Table D-4 – Estimated Horsepower of 

Diesel Well Pump Engines1

District Average Minimum Maximum 

Bay Area AQMD 148 104 248

Butte County AQMD 129 102 157

Colusa County APCD 141 116 189

Feather River AQMD 144 99 190

Glenn County APCD 132 103 162

Imperial County APCD 114 98 205

Monterey Bay Unified APCD 149 112 187

Sacramento Metropolitan AQMD 157 98 203

San Diego County APCD 130 56 305

San Joaquin Valley Unified APCD 196 76 705

San Luis Obispo County APCD 162 100 346

Santa Barbara County APCD 151 63 446

South Coast AQMD 180 100 363

Ventura County APCD 181 98 401

Yolo/Solano AQMD 149 103 211

Statewide Average 184 56 705

1. Statewide average assigned to areas without data 
D-9 

Booster Pumps 

Data to calculate booster pump engine horsepower profiles is summarized in 

Table D-3. All parameters except for the pressure head and friction head are average 

values obtained from Tables 19 and 20 of the 2003 Farm and Ranch Irrigation Survey. 

Table D-5 summarizes the horsepower profiles of the three types of booster pump 

engines. 

Table D-5 – Estimated Horsepower of 

Diesel Booster Pump Engines 

Type 

Percent 

of Type 

Calculated 

HP 

Tailwater 46% 51 

Tailwater 23% 85 

Tailwater 18% 141 

Tailwater 3% 197 

Tailwater 6% 282 

Tailwater 3% 556 

Tailwater Average 111 

Pond/Lake 10% 40 

Pond/Lake 19% 66 

Pond/Lake 9% 111 

Pond/Lake 12% 155 

Pond/Lake 37% 221 

Pond/Lake 12% 387 

Pond/Lake Average 176 

Relift 21% 53 

Relift 19% 88 

Relift 17% 147 

Relift 16% 205 

Relift 21% 294 

Relift 4% 620 

Relift Average 177 

Activity 

The average annual usage of diesel irrigation pump engines is assumed to be 

1,000 hours. Data on electrical use for Pacific Gas and Electric small and large 

agricultural electric rate payers indicates that average pumping hours may have 

ranged from 187 to 4,569 for year 2003 (PG&E, 2004). The 2003 Farm and Ranch 

Irrigation Survey indicates that the average hours of operation of well pump engines 

was 1,016 hours. Finally, analysis of irrigation pump engines replaced under the 

Carl Moyer Program shows that the average pump usage is about 1,000 hours. 

Age Distribution 

The average useful life of an irrigation pump engine is about 20 years; that is, half of 

the engines that were purchased 20 years ago will still be in operation. Engines 
D-10 

replaced under the Carl Moyer Program were as old as 61 years but averaged 18 

years of age. The American Society of Agricultural Engineers has estimated the 

average agricultural engine is used 20,000 hours (ASAE, 2005). At an average 

annual usage of 1,000 hours, 20 years is a reasonable estimate of useful life. 

The actual age of irrigation pump engines was available for 1,032 engines in the 

Sacramento Non-Attainment area and the 1,300 pump engines replaced through the 

Carl Moyer Program from 1997 through 2003. For all other pump engines, an age 

distribution was calculated using the methodology used in the ARB OFFROAD 

model. Table D-6 shows the base year age distribution. The OFFROAD age 

distribution methodology takes into account an “S”-shaped scrappage curve and 

historic diesel engine populations reported in the Farm and Ranch Irrigation Surveys 

for the years 1984, 1988, 1994, 1998, and 2003. For all other years within the 

complete 40 year time span, the average yearly growth between the years 1984 and 

2003 was assumed. (Note: for future years, different growth rates are assumed and 

will be discussed in the “Growth” section). 
D-11 

Table D-6 – Base Year Age Distribution of 

Diesel Irrigation Pump Engines 

Age Model Year Percent 

0 2003 8.3%

1 2002 7.7%

2 2001 7.5%

3 2000 7.2%

4 1999 3.1%

5 1998 3.0%

6 1997 2.8%

7 1996 2.6%

8 1995 4.4%

9 1994 4.3%

10 1993 4.1%

11 1992 3.9%

12 1991 3.7%

13 1990 3.5%

14 1989 4.5%

15 1988 4.3%

16 1987 4.0%

17 1986 3.7%

18 1985 2.5%

19 1984 2.9%

20 1983 2.4%

21 1982 1.5%

22 1981 1.3%

23 1980 1.1%

24 1979 1.0%

25 1978 0.8%

26 1977 0.7%

27 1976 0.6%

28 1975 0.5%

29 1974 0.4%

30 1973 0.4%

31 1972 0.3%

32 1971 0.2%

33 1970 0.2%

34 1969 0.2%

35 1968 0.1%

36 1967 0.1%

37 1966 0.1%

38 1965 0.1%

39 1964 0.1%

40 1963 0.0%
D-12 

Load Factor 

The load factor assumed for agricultural irrigation pump engines was 65 percent. 

This figure was based on extensive discussions with engine dealers, manufacturers, 

and irrigation experts. 

Emission Factors 

Emission factors for CO, hydrocarbons, NOx, PM, and CO2 were used to estimate 

emissions. These emission factors are from the OFFROAD model and are based 

upon source tests of engines. The OFFROAD emission factors are in three parts: 

the zero hour emission factor; the base emission rate for a new engine; and a 

deterioration factor, which is dependant on the cumulative number of hours an 

engine has been in operation. The final emission factor is the zero hour emission 

factor plus the deterioration factor times the cumulative engine use (in hours). 

Because engines can only deteriorate a certain amount before they cease to 

operate, deterioration was capped at the average useful life of the engine, or 

20 years (20,000 hours). These emission factors are summarized in Table D-7. 

OFFROAD diesel emission factors require adjustment for calculation of TOG: 

hydrocarbon emissions must be multiplied by a factor of 1.44 to get TOG. 

OFFROAD emission factors for NOx and PM also need to be corrected for the 

difference between the fuels the factors were developed with and the fuels actually 

used in California. These fuel correction factors are specific for the year of emission 

estimates, the model year of the equipment, and the horsepower of the equipment. 

For NOx, the fuel correction factor varies between 0.93 and 1; for PM, the fuel 

correction factor varies between 0.72 and 1.0. For ROG, the fuel correction factor is 

0.72 for diesel fuel. 
D-13 

Table D-7 – Diesel Emission Factors 

(g/hp-hr) (g/hp-hr2 ) (g/hp-hr) (g/hp-hr2 ) (g/hp-hr) (g/hp-hr2 ) (g/hp-hr) (g/hp-hr2 )

HP Year HC HC det CO CO det NOX NOX det PM PM det

26 - 50 <= 1987 1.84 2.35E-04 5 5.13E-04 7 1.05E-04 0.76 5.89E-05

26 - 50 1988 - 1998 1.8 2.30E-04 5 5.13E-04 6.9 1.04E-04 0.76 5.89E-05

26 - 50 1999 - 2003 1.45 1.85E-04 4.1 4.20E-04 5.55 1.03E-04 0.6 4.65E-05

26 - 50 2004 0.64 9.80E-05 3.27 3.34E-04 5.1 9.33E-05 0.43 3.36E-05

26 - 50 2005 0.37 6.90E-05 3 3.05E-04 4.95 9.67E-05 0.38 2.93E-05

26 - 50 2006 - 2007 0.24 5.45E-05 2.86 2.90E-04 4.88 9.83E-05 0.35 2.72E-05

26 - 50 2008 - 2012 0.1 4.00E-05 2.72 2.76E-04 4.8 1.00E-04 0.16 1.22E-05

26 - 50 2013 - 2020 0.1 4.00E-05 2.72 2.76E-04 2.9 6.04E-05 0.01 1.11E-06

51 - 120 <= 1987 1.44 6.66E-05 4.8 1.27E-04 13 3.01E-04 0.84 6.11E-05

51 - 120 1988 - 1997 0.99 4.58E-05 3.49 9.23E-05 8.75 2.02E-04 0.69 5.02E-05

51 - 120 1998 - 2003 0.99 4.58E-05 3.49 9.23E-05 6.9 1.60E-04 0.69 5.02E-05

51 - 120 2004 0.46 3.33E-05 3.23 8.55E-05 5.64 1.03E-04 0.39 2.85E-05

51 - 120 2005 0.28 2.92E-05 3.14 8.33E-05 5.22 8.40E-05 0.29 2.12E-05

51 - 120 2006 - 2007 0.19 2.71E-05 3.09 8.21E-05 5.01 7.45E-05 0.24 1.76E-05

51 - 120 2008 - 2011 0.1 2.50E-05 3.05 8.10E-05 2.89 3.80E-05 0.2 1.45E-05

51 - 120 2012 0.09 2.31E-05 3.05 8.10E-05 2.53 3.33E-05 0.07 4.96E-06

51 - 120 2013 - 2014 0.09 2.31E-05 3.05 8.10E-05 2.53 3.33E-05 0.01 9.33E-07

51 - 120 2015 - 2020 0.07 1.74E-05 3.05 8.10E-05 1.4 1.84E-05 0.01 9.33E-07

121 - 175 <= 1969 1.32 6.11E-05 4.4 1.16E-04 14 3.24E-04 0.77 5.60E-05

121 - 175 1970 - 1971 1.1 5.09E-05 4.4 1.16E-04 13 3.01E-04 0.66 4.80E-05

121 - 175 1972 - 1979 1 4.63E-05 4.4 1.16E-04 12 2.78E-04 0.55 4.00E-05

121 - 175 1980 - 1984 0.94 4.35E-05 4.3 1.14E-04 11 2.54E-04 0.55 4.00E-05

121 - 175 1985 - 1987 0.88 4.07E-05 4.2 1.11E-04 11 2.54E-04 0.55 4.00E-05

121 - 175 1988 - 1996 0.68 3.15E-05 2.7 7.14E-05 8.17 1.89E-04 0.38 2.76E-05

121 - 175 1997 - 2002 0.68 3.15E-05 2.7 7.14E-05 6.9 1.60E-04 0.38 2.76E-05

121 - 175 2003 0.33 2.79E-05 2.7 7.14E-05 5.26 9.64E-05 0.24 1.70E-05

121 - 175 2004 0.22 2.63E-05 2.7 7.14E-05 4.72 7.52E-05 0.19 1.35E-05

121 - 175 2005 - 2006 0.16 2.57E-05 2.7 7.14E-05 4.44 6.46E-05 0.16 1.18E-05

121 - 175 2007 - 2011 0.1 2.50E-05 2.7 7.14E-05 2.45 3.20E-05 0.14 1.00E-05

121 - 175 2012 - 2014 0.09 2.17E-05 2.7 7.14E-05 2.27 2.96E-05 0.01 4.67E-07

121 - 175 2015 - 2020 0.05 1.17E-05 2.7 7.14E-05 0.27 3.56E-06 0.01 4.67E-07

176 - 250 <= 1969 1.32 6.11E-05 4.4 1.16E-04 14 3.24E-04 0.77 5.60E-05

176 - 250 1970 - 1971 1.1 5.09E-05 4.4 1.16E-04 13 3.01E-04 0.66 4.80E-05

176 - 250 1972 - 1979 1 4.63E-05 4.4 1.16E-04 12 2.78E-04 0.55 4.00E-05

176 - 250 1980 - 1984 0.94 4.35E-05 4.3 1.14E-04 11 2.54E-04 0.55 4.00E-05

176 - 250 1985 - 1987 0.88 4.07E-05 4.2 1.11E-04 11 2.54E-04 0.55 4.00E-05

176 - 250 1988 - 1995 0.68 3.15E-05 2.7 7.14E-05 8.17 1.89E-04 0.38 2.76E-05

176 - 250 1996 - 2002 0.32 1.48E-05 0.92 2.43E-05 6.25 1.45E-04 0.15 7.96E-06

176 - 250 2003 0.19 2.09E-05 0.92 2.43E-05 5 9.05E-05 0.12 6.51E-06

176 - 250 2004 0.14 2.30E-05 0.92 2.43E-05 4.58 7.23E-05 0.11 6.03E-06

176 - 250 2005 - 2006 0.12 2.40E-05 0.92 2.43E-05 4.38 6.33E-05 0.11 5.79E-06

176 - 250 2007 - 2010 0.1 2.50E-05 0.92 2.43E-05 2.45 3.18E-05 0.11 5.59E-06

176 - 250 2011 - 2013 0.07 1.83E-05 0.92 2.43E-05 1.36 1.77E-05 0.01 4.55E-07

176 - 250 2014 - 2020 0.05 1.17E-05 0.92 2.43E-05 0.27 3.56E-06 0.01 4.55E-07
D-14 

Table D-7 – Diesel Emission Factors (Continued) 

(g/hp-hr) (g/hp-hr2 ) (g/hp-hr) (g/hp-hr2 ) (g/hp-hr) (g/hp-hr2 ) (g/hp-hr) (g/hp-hr2 )

HP Year HC HC det CO CO det NOX NOX det PM PM det

251 - 500 <= 1969 1.26 4.39E-05 4.2 8.32E-04 14 2.33E-04 0.74 3.93E-05

251 - 500 1970 - 1971 1.05 3.66E-05 4.2 8.32E-04 13 2.16E-04 0.63 3.34E-05

251 - 500 1972 - 1979 0.95 3.31E-05 4.2 8.32E-04 12 2.00E-04 0.53 2.81E-05

251 - 500 1980 - 1984 0.9 3.14E-05 4.2 8.32E-04 11 1.83E-04 0.53 2.81E-05

251 - 500 1985 - 1987 0.84 2.93E-05 4.1 8.12E-04 11 1.83E-04 0.53 2.81E-05

251 - 500 1988 - 1995 0.68 2.37E-05 2.7 5.35E-05 8.17 1.36E-04 0.38 2.02E-05

251 - 500 1996 - 2000 0.32 1.12E-05 0.92 1.82E-05 6.25 1.04E-04 0.15 7.96E-06

251 - 500 2001 0.19 1.95E-05 0.92 1.82E-05 4.95 7.34E-05 0.12 6.51E-06

251 - 500 2002 0.14 2.22E-05 0.92 1.82E-05 4.51 6.32E-05 0.11 6.03E-06

251 - 500 2003 - 2004 0.12 2.36E-05 0.92 1.82E-05 4.29 5.81E-05 0.11 5.79E-06

251 - 500 2005 0.1 2.50E-05 0.92 1.82E-05 4 5.30E-05 0.11 5.55E-06

251 - 500 2006 - 2010 0.1 2.50E-05 0.92 1.82E-05 2.45 3.18E-05 0.11 5.55E-06

251 - 500 2011 - 2013 0.07 1.83E-05 0.92 1.82E-05 1.36 1.77E-05 0.01 4.55E-07

251 - 500 2014 - 2020 0.05 1.17E-05 0.92 1.82E-05 0.27 3.56E-06 0.01 4.55E-07

501 - 750 <= 1969 1.26 4.39E-05 4.2 8.32E-04 14 2.33E-04 0.74 3.93E-05

501 - 750 1970 - 1971 1.05 3.66E-05 4.2 8.32E-04 13 2.16E-04 0.63 3.34E-05

501 - 750 1972 - 1979 0.95 3.31E-05 4.2 8.32E-04 12 2.00E-04 0.53 2.81E-05

501 - 750 1980 - 1984 0.9 3.14E-05 4.2 8.32E-04 11 1.83E-04 0.53 2.81E-05

501 - 750 1985 - 1987 0.84 2.93E-05 4.1 8.12E-04 11 1.83E-04 0.53 2.81E-05

501 - 750 1988 - 1995 0.68 2.37E-05 2.7 5.35E-05 8.17 1.36E-04 0.38 2.02E-05

501 - 750 1996 - 2001 0.32 1.12E-05 0.92 1.82E-05 6.25 1.04E-04 0.15 7.96E-06

501 - 750 2002 0.19 1.95E-05 0.92 1.82E-05 4.95 7.34E-05 0.12 6.51E-06

501 - 750 2003 0.14 2.22E-05 0.92 1.82E-05 4.51 6.32E-05 0.11 6.03E-06

501 - 750 2004 - 2005 0.12 2.36E-05 0.92 1.82E-05 4.29 5.81E-05 0.11 5.79E-06

501 - 750 2006 - 2010 0.1 2.50E-05 0.92 1.82E-05 2.45 3.18E-05 0.11 5.55E-06

501 - 750 2011 - 2013 0.07 1.83E-05 0.92 1.82E-05 1.36 1.77E-05 0.01 4.55E-07

501 - 750 2014 - 2020 0.05 1.17E-05 0.92 1.82E-05 0.27 3.56E-06 0.01 4.55E-07

751 - 9999 <= 1969 1.26 4.39E-05 4.2 8.32E-04 14 2.33E-04 0.74 3.93E-05

751 - 9999 1970 - 1971 1.05 3.66E-05 4.2 8.32E-04 13 2.16E-04 0.63 3.34E-05

751 - 9999 1972 - 1979 0.95 3.31E-05 4.2 8.32E-04 12 2.00E-04 0.53 2.81E-05

751 - 9999 1980 - 1984 0.9 3.14E-05 4.2 8.32E-04 11 1.83E-04 0.53 2.81E-05

751 - 9999 1985 - 1987 0.84 2.93E-05 4.1 8.12E-04 11 1.83E-04 0.53 2.81E-05

751 - 9999 1988 - 1999 0.68 1.12E-05 2.7 5.35E-05 8.17 1.36E-04 0.38 2.02E-06

751 - 9999 2000 - 2005 0.32 1.12E-05 0.92 1.82E-05 6.25 1.04E-04 0.15 7.96E-06

751 - 9999 2006 0.19 1.95E-05 0.92 1.82E-05 4.95 7.34E-05 0.12 6.51E-06

751 - 9999 2007 0.14 2.22E-05 0.92 1.82E-05 4.51 6.32E-05 0.11 6.03E-06

751 - 9999 2008 - 2009 0.12 2.36E-05 0.92 1.82E-05 4.29 5.81E-05 0.11 5.79E-06

751 - 9999 2010 0.1 2.50E-05 0.92 1.82E-05 4.08 5.30E-05 0.11 5.55E-06

751 - 9999 2011 - 2014 0.1 2.50E-05 0.92 1.82E-05 2.36 3.06E-05 0.06 2.78E-06

751 - 9999 2015 - 2020 0.05 1.17E-05 0.92 1.82E-05 2.36 3.06E-05 0.02 1.11E-06
D-15 

Growth 

In April, 2005, the ARB agricultural advisory committee approved a set of growth 

factors for various types of agricultural equipment. For most categories, including 

irrigation pump engines, the growth factor selected was irrigated acreage, as 

collected by the California Department of Conservation’s Farmland Monitoring and 

Mapping Program for the years 1996-2002 (reference 12). These growth factors are 

defined by county for the San Joaquin Valley; an average is used for the rest of the 

State. Table D-8 presents these growth factors. With the exception of Madera and 

Merced counties, the growth of irrigated acreage is declining. 

Since usage of diesel agricultural irrigation pump engines is not only defined by the 

amount of agricultural acreage, but also by market forces including energy costs, the 

growth rate of these engines will be revisited in future years as the USDA publishes 

new Farm and Ranch Irrigation Surveys. These surveys are performed 

approximately every five years. 

Table D-8 – Growth Rates by County 

County Name 

Growth Factor 

(per year) 

Fresno -0.73%

Kern -0.33%

Kings -0.14%

Madera 0.20%

Merced 0.03%

San Joaquin -0.32%

Stanislaus -0.12%

Tulare -0.62%

All Other 

Counties -0.26%

To calculate emissions growth for future years, the base year population was grown 

using the growth factors described above using the methodology used for the ARB 

OFFROAD model. Because the number of diesel irrigation engines increased 

dramatically between 1998 and 2003, the base year age distribution contains a large 

percentage of late model engines that declines in future years as these engines are 

retired. 
D-16 

RESULTS 

Table D-9 shows the statewide emissions for the base year (2003) by local air district 

for all diesel pump engines. More than half of the emissions of diesel irrigation pump 

engines are in the San Joaquin Valley Unified APCD, due to both the large number 

of pump engines in that district and because wells on the west side of the district 

tend to be very deep and therefore require much larger engines. Table D-10 shows 

the statewide emissions by horsepower and by pump engine portability. About 

two-thirds of the statewide emissions are from stationary pump engines based on the 

Booz-Hamilton assumption presented in table D-1. Table D-11 shows the forecasted 

statewide emissions (does not include the benefits of the regulation). Emissions 

decline over time because of the negative growth rate which reflects the 

disappearance of agricultural land in California and because as time goes on, 

existing federal off-road compression ignition engine certification standards result in 

the replacement of older, dirtier engines with newer, cleaner engines. By 2025, 

emissions of all pollutants (except CO2) are less than half those seen in 2003. 
D-17 

Table D-9 – 2003 Diesel Agricultural Irrigation Pump Engine Emissions 

By Local Air District 

(tons per day) 

District Name CO CO2 DPM HC NOx PM PM10 PM25 ROG SOx TOG

Amador County APCD 0.0 3.4 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0

Antelope Valley APCD 0.1 7.2 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0

Bay Area AQMD 0.2 28.4 0.0 0.1 0.5 0.0 0.0 0.0 0.0 0.0 0.1

Butte County AQMD 0.7 85.4 0.1 0.2 1.4 0.1 0.1 0.1 0.1 0.0 0.2

Calaveras County AQMD 0.0 0.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Colusa County APCD 0.4 57.6 0.0 0.1 0.9 0.1 0.0 0.0 0.1 0.0 0.2

El Dorado County APCD 0.0 2.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Feather River AQMD 0.7 86.5 0.1 0.2 1.4 0.1 0.1 0.1 0.1 0.0 0.2

Glenn County APCD 0.4 48.7 0.0 0.1 0.8 0.1 0.0 0.0 0.1 0.0 0.1

Great Basin Unified APCD 0.2 29.6 0.0 0.1 0.5 0.0 0.0 0.0 0.0 0.0 0.1

Imperial County APCD 0.1 20.4 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.1

Kern County APCD 0.0 3.6 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0

Lake County AQMD 0.0 5.8 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0

Lassen County APCD 0.3 34.1 0.0 0.1 0.5 0.0 0.0 0.0 0.1 0.0 0.1

Mariposa County APCD 0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Mendocino County AQMD 0.0 4.5 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0

Modoc County APCD 0.2 21.3 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.1

Mojave Desert AQMD 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Monterey Bay Unified APCD 0.8 122.0 0.1 0.2 2.0 0.1 0.1 0.1 0.2 0.0 0.3

North Coast Unified APCD 0.1 13.0 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0

Northern Sierra AQMD 0.1 9.7 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0

Northern Sonoma County APCD 0.0 3.8 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0

Placer County APCD 0.1 9.3 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0

Sacramento Metropolitan AQMD 0.1 16.9 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0

San Diego County APCD 0.3 32.9 0.0 0.1 0.5 0.0 0.0 0.0 0.1 0.0 0.1

San Joaquin Valley Unified APCD 11.2 1451.2 1.1 2.4 22.9 1.3 1.1 1.1 2.1 0.1 3.5

San Luis Obispo County APCD 0.2 23.4 0.0 0.0 0.4 0.0 0.0 0.0 0.0 0.0 0.1

Santa Barbara County APCD 0.3 42.9 0.0 0.1 0.7 0.0 0.0 0.0 0.1 0.0 0.1

Shasta County AQMD 0.2 23.3 0.0 0.0 0.4 0.0 0.0 0.0 0.0 0.0 0.1

Siskiyou County APCD 0.4 48.5 0.0 0.1 0.8 0.0 0.0 0.0 0.1 0.0 0.1

South Coast AQMD 0.0 3.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Tehama County APCD 0.3 39.2 0.0 0.1 0.6 0.0 0.0 0.0 0.1 0.0 0.1

Tuolumne County APCD 0.0 0.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Ventura County APCD 0.2 29.1 0.0 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.1

Yolo/Solano AQMD 0.9 143.2 0.1 0.3 2.3 0.1 0.1 0.1 0.2 0.0 0.4

Statewide Total 18.7 2452.1 1.9 4.2 39.0 2.3 1.9 1.9 3.7 0.2 6.1
D-18 

Table D-10 – 2003 Diesel Agricultural Irrigation Pump Engine Emissions 

By Horsepower and Portability 

(tons per day) 

Table D-11 – Forecasted Diesel Agricultural 

Irrigation Pump Engine Emissions 

 (tons per day) 

Pollutant 2003 2005 2010 2015 2020

CO 18.7 17.7 15.0 12.9 11.3

CO2 2452.1 2439.4 2407.5 2375.6 2343.7

DPM 1.9 1.9 1.6 1.4 1.0

HC 4.2 4.1 3.6 3.0 2.4

NOx 39.0 37.6 32.5 26.3 19.3

PM 2.3 2.2 1.9 1.6 1.2

PM10 1.9 1.9 1.6 1.4 1.0

PM25 1.9 1.8 1.6 1.3 1.0

ROG 3.7 3.5 3.1 2.6 2.1

SOx 0.2 0.2 0.2 0.1 0.1

TOG 6.1 5.9 5.1 4.3 3.5

Portability Horsepower CO CO2 DPM HC NOx PM PM10 PM25 ROG SOx TOG

Portable 26 to 50 Horsepower 0.1 6.3 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.1

Portable 51 to 120 Horsepower 1.9 231.8 0.3 0.6 4.1 0.4 0.3 0.3 0.5 0.0 0.9

Portable 121 to 175 Horsepower 1.1 162.5 0.1 0.3 2.7 0.2 0.1 0.1 0.3 0.0 0.4

Portable 176 to 250 Horsepower 0.5 98.8 0.1 0.1 1.5 0.1 0.1 0.1 0.1 0.0 0.2

Portable 251 to 500 Horsepower 0.6 55.8 0.0 0.1 0.8 0.0 0.0 0.0 0.1 0.0 0.1

Portable 501 to 750 Horsepower 0.1 7.9 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0

4.3 563.0 0.6 1.2 9.3 0.7 0.6 0.6 1.0 0.0 1.7

Stationary 26 to 50 Horsepower 0.0 0.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Stationary 51 to 120 Horsepower 0.8 98.5 0.1 0.3 1.7 0.2 0.1 0.1 0.2 0.0 0.4

Stationary 121 to 175 Horsepower 4.4 649.9 0.5 1.2 10.6 0.6 0.5 0.5 1.0 0.1 1.7

Stationary 176 to 250 Horsepower 2.7 560.7 0.4 0.8 8.8 0.4 0.4 0.3 0.7 0.0 1.2

Stationary 251 to 500 Horsepower 5.6 505.3 0.3 0.7 7.4 0.3 0.3 0.3 0.6 0.0 1.0

Stationary 501 to 750 Horsepower 0.9 71.2 0.0 0.1 1.1 0.1 0.0 0.0 0.1 0.0 0.1

Stationary >751 Horsepower 0.0 2.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

14.4 1889.1 1.4 3.0 29.7 1.6 1.4 1.3 2.6 0.1 4.4

18.7 2452.1 1.9 4.2 39.0 2.3 1.9 1.9 3.7 0.2 6.1

Portable Total

Stationary Total

All Engines Total
D-19 

REFERENCES FOR APPENDIX D 

1. US Department of Agriculture National Agricultural Statistics Service, 2003 

Farm and Ranch Irrigation Survey (On the internet at 

http://www.nass.usda.gov/census/census02/fris/fris03.htm) and California 

Well Pump Data by County (Special Request by the Air Resources Board), 

June 2005. 

2. Personal communication from Hao Quinn, Sacramento Metropolitan Air 

Quality Management District 

3. Personal communication from Al Baez, South Coast Air Quality Management 

District 

4. US Geological Survey, Estimated Use of Water in the United States

County-Level Data for 2000. On the internet at 

http://water.usgs.gov/watuse/data/2000/index.html 

5. California Department of Water Resources, California Land and Water Use 

Datasets. On the internet at: 

 http://www.landwateruse.water.ca.gov/basicdata/landuse/landusesurvey.cfm 

6. Booz-Allen & Hamilton, Off-Road Mobile Equipment Emission Inventory 

Estimate, January 1992. 

7. US Geological Survey, California Ground Water Levels. On the internet at: 

 http://nwis.waterdata.usgs.gov/ca/nwis/gwlevels. 

8. National Resources Conservation Service, National Engineering Handbook 

Part 652 – Irrigation guide, Chapter 12. On the internet at 

http://www.wcc.nrcs.usda.gov/nrcsirrig/irrig-handbooks-part652.html 

9. Sonoma Technology Incorporated, Emission Inventory of Agricultural Internal 

Combustion Engines used for Irrigation in the SJVUAPCD, Final Report, STI95240-1569, August 1996. 

10. PG&E, 2004. Personal Communication (email attachment), Keith Coyne, 

Pacific Gas and Electric, to Carol McLaughlin, ARB Stationary Source 

Division, 2004. 

11. ASAE, 2005. Personal Communication (email) from Carla Miller, American 

Society of Agricultural Engineers, to Barbara Cook, ARB Stationary Source 

Division, February 9, 2005. 

12. California Department of Conservation, Farmland Monitoring and Mapping 

Program, California Farmland Conversion Report, on the internet at: 

 http://www.consrv.ca.gov/dlrp/fmmp/index.htm.