Rule 403 Agricultural Handbook 

Measures to Reduce Dust from Agricultural Operations in the 

South Coast Air Basin 

Prepared by 

South Coast 

Air Quality 

Management District 

December 1998
	




















		













	
	










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TABLE OF CONTENTS 

 Page 

Section I 

Purpose ...... 1 

Rule 403 Applicability 1 

Conservation Practice Selection 2 

Alternative Conservation Practices 3 

Technical Justifications 3 

Conservation Practice Implementation Guidance 3 

Section II 

Active Conservation Practices 4 

Inactive Conservation Practices 5 

Farm Yard Area Conservation Practices 7 

Track-Out Conservation Practices 8 

Unpaved Road Conservation Practices 9 

Storage Pile Conservation Practices 10 

Section III 

Submittal Instructions for Alternative Conservation Practices 11 

Section IV 

Submittal Instructions for a Justification Statement 12 

Section V 

Conservation Practice Self-Monitoring Form 13 

Section VI 

Opting for Rule 403 general provisions 16

Failure to comply with Rule 403 17

LIST OF FIGURES 

Figure 1: Boundaries of the South Coast Air Basin 1
(1/17) 12/15/98 

Section I 

Purpose 

To reduce the dust and corresponding PM10 emissions (Particulate Matter less than 10 microns 

in diameter) generated from agricultural operations and to meet federal requirements to 

implement appropriate particulate matter reduction programs. 

Rule 403 Applicability

Agricultural operations that have 10 contiguous acres or less, or are primarily used for the 

purpose of raising fowl or animals, or are outside the South Coast Air Basin (see Figure 1)1 will 

remain exempt from Rule 403. Agricultural operations in excess of 10 contiguous acres and are 

conducted within the South Coast Air Basin can voluntarily implement the conservation 

practices and complete the self-monitoring form no later than June 30, 1999, and maintain their 

exemption from all Rule 403 requirements. After July 1, 1999, producers who do not implement 

the conservation practices become subject to all other Rule 403 requirements. Failure to meet 

Rule 403 requirements may result in mandatory conservation class(es), required dust control 

plans, fines, or other penalties. 

FIGURE 1 

 

1

 If your agricultural operation is outside the South Coast Air Basin or 10 contiguous acres or 

less, conservation practices are encouraged, but no actions are required.
(2/17) 12/15/98 

Section I 

Conservation Practice Selection

Producers who voluntarily implement the suggested minimum number of conservation 

practices listed under each category in Section II by June 30, 1999 and complete and 

maintain the self-monitoring form (Section V) will be exempt from the requirements of 

Rule 403. The list of conservation practices will be updated annually to reflect any new 

developments in control technology. Producers that do not elect to implement sufficient 

conservation practices become subject to all Rule 403 requirements beginning July 1, 

1999. 

The list of conservation practices is divided into the six categories presented below. The 

italicized text underneath the category descriptions represent the suggested minimum 

number of conservation practices to be implemented in order to maintain a Rule 403 

exemption. Producers can also choose alternative conservation practices or provide a 

technical justification if the suggested minimum number of conservation practices for a 

category (e.g., inactive) can not be implemented on-site (see Sections III and IV)

1. Active - applicable to agricultural activities involved in disturbing the soil (not 

applicable to orchards, vine crops, nurseries, range land, and irrigated 

pasture).

(producers must cease activities during wind conditions greater than 25 mph and 

 implement at least one of the other conservation practices) 

2. Inactive - applicable to agricultural sites when no soil disturbance activities are being 

conducted (not applicable to orchards, vine crops, nurseries, range land, 

and irrigated pasture)

(at least three of the conservation practices must be implemented within this category) 

3. Farm Yard Areas - applicable to disturbed surfaces used by people or vehicles (e.g., 

equipment storage yards) on at least eight calendar days per year 

(at least one of the conservation practices must be implemented within this category) 

4. Track-Out - applicable to vehicles or other equipment carrying soil from an unpaved 

surface to a paved public road 

(at least one of the conservation practices must be implemented within this category) 

5. Unpaved Roads - applicable to private unpaved roads used by producers 

(at least one of the conservation practices must be implemented within this category) 

6. Storage Piles - applicable accumulations of material 

(at least one of the conservation practices must be implemented within this category)
(3/17) 12/15/98 

Section I 

Alternative Conservation Practices 

Producers can implement alternative conservation practices that are more suitable to their 

specific farming operations. Producers that elect to implement alternative conservation 

practices and want to qualify for the Rule 403 exemption must provide a description of 

the alternative conservation practices to the AQMD. Please refer to Section III (page 11) 

of this Handbook for AQMD submittal instructions. 

Technical Justifications 

In the event that there are special technical (e.g., non-economic) circumstances, including 

safety, which prevent implementation of the suggested minimum number of conservation 

practices for each category in Section II, producers can submit a justification statement to 

the AQMD. The justification statement must explain the reason(s) why the suggested 

minimum number of conservation practices within a category can not be implemented 

on-site. Please refer to Section IV (page 12) of this Handbook for AQMD submittal 

instructions. 

Conservation Practice Implementation Guidance

Technical assistance with selecting, adopting, and implementing any of the conservation 

practices listed in Section II is available, free of charge, from your local Resource 

Conservation District (RCD), Natural Resources Conservation Service (NRCS) office, or 

Cooperative Extension office. Cost-sharing incentives to implement practices that reduce 

dust may also be available from these resource agencies. Phone numbers of RCD, 

NRCS, and Cooperative Extension offices within the South Coast Air Basin are listed 

below. 

NRCS/RCD Offices 

 Los Angeles, Urban Office (213) 580-8890 

 Riverside/Orange County (909) 684-1552 (909) 683-7691 

 Redlands (909) 799-7407 

 San Jacinto (909) 654-7733 (909) 654-7139 

 Apple Valley (760) 242-2906 

University of California Cooperative Extension 

 (909) 683-6491 
(4/17) 12/15/98 

Section II 

1. Active Conservation Practices 

Exempted operations: orchards, vine crops, nurseries, range land, and irrigated pasture 

Producers that want a Rule 403 exemption must implement the Activity Modification 

conservation practice and at least one of the other conservation practices. 

Activity Modification 

Cease soil preparation and/or maintenance activities (does not include harvesting 

activities) during wind conditions in excess of 25 miles per hour (mph) unless such 

activities result in a net reduction in wind driven fugitive dust (i.e., if wind driven dust is 

not visible from tilled soil, but is visible from untilled soil within the same agricultural 

parcel). A one-day exemption from this prohibition is allowed if wind conditions in 

excess of 25 mph have occurred on two consecutive days. 

Producers that want a Rule 403 exemption must implement at least one of the other four 

conservation practices listed below. 

1. Soil Moisture Monitoring 

Ensure adequate soil moisture levels at the time of tillage or soil maintenance activities to 

prevent visible dust emissions from extending more than 100 feet from any source within 

the agricultural parcel. 

2. Irrigation System 

Irrigate or bed fields as soon as feasible after land leveling or releveling to prevent the 

field being left in a smooth dry condition. 

3. Minimum Tillage 

Utilize conservation tillage practices to manage the amount, orientation and distribution 

of crop and other plant residues on the soil surface year-round, while growing crops in 

narrow slots or tilled strips. Your local NRCS, RCD, or Cooperative Extension office can 

provide guidance on various minimum tillage practices.

4. Mulching 

Uniformly distribute plant residues, manure, or other suitable materials not produced on 

the site to the soil surface prior to disturbing the soil.
(5/17) 12/15/98 

Section II 

2. Inactive Conservation Practices

Exempted operations: orchards, vine crops, nurseries, range land, and irrigated pasture 

Producers that want a Rule 403 exemption must implement at least three of the following 

nine conservation practices listed below. 

1. Local Jurisdiction Ordinance 

Compliance with a local jurisdiction's ordinance intended to reduce windblown dust 

emissions. 

2. Cover Crop

Establish a cover crop that establishes a minimum of 60 percent ground cover on fields 

that will remain fallow until the next crop planting. Vegetative growth to be managed, if 

necessary, by mowing, grazing, approved chemicals or other means that maintain the 

necessary cover. (Native or volunteer vegetation that meets the minimum ground cover 

requirements also represents an acceptable cover crop). 

3. Crop Residue Management

Maintain crop residues from previous crops that establishes a minimum of 60 percent 

ground cover on fields that will remain fallow until the next crop planting. Implements 

such as undercutters or sweeps that sever roots and lift weeds without burying or 

destroying much of the residue are most efficient for maintaining surface cover. 

4. Surface Roughening 

Conduct surface roughening by bedding, rough disking, or tillage that leaves the surface 

covered with stable clods. Disc fallow fields in the early spring to get the winter weeds 

before they mature seed and before it dries out so clods will be produced. List or bed up 

in May to get early summer weeds before they seed and before it is too dry to bed. 

5. Minimum Tillage 

Utilize conservation tillage practices to manage the amount, orientation and distribution 

of crop and other plant residues on the soil surface year-round, while growing crops in 

narrow slots or tilled strips. Your local NRCS, RCD, or Cooperative Extension office can 

provide guidance on various minimum tillage practices.
(6/17) 12/15/98 

Section II 

2. Inactive Conservation Practices (Concluded)

Exempted operations: orchards, vine crops, nurseries, range land, and irrigated pasture 

6. Cross Wind Stripcropping 

Establish crops in strips established across the prevailing wind erosion direction and 

arranged so that strips susceptible to wind erosion are alternated with strips having a 

protective cover that is resistant to wind erosion.

7. Field Windbreaks 

Plant or maintain a single or multiple row of trees or shrubs adjacent to windward edge of 

the field as close to perpendicular as practical with the direction of erosive winds. Avoid 

conflicts with any above or below ground utilities. Local RCD, NRCS, or Cooperative 

Extension staff can provide technical assistance on selecting proper tree species, 

appropriate spacing, and maintenance requirements. 

8. Ridge Roughness

Establish ridges by normal tillage and planting equipment as close to perpendicular as 

practical with the direction of erosive winds (not appropriate for unstable soils such as 

sands or loamy sands). After establishment, ridges shall be maintained through those 

periods when wind erosion is expected to occur, or until growing crops provide enough 

cover to protect the soil from wind erosion. 

9. Wind Barriers 

Plant or maintain perennial or annual plants interspersed throughout a crop field as close 

to perpendicular as practical with the direction of erosive winds. To be effective, the 

selected plant(s) must create a stand at least three feet tall. Selection of plants for wind 

barriers should favor species or varieties tolerant to herbicides used on adjacent crops. 

Local RCD, NRCS, or Cooperative Extension staff can provide technical assistance on 

selecting proper tree species, appropriate spacing, and maintenance requirements. 
(7/17) 12/15/98 

Section II 

3. Farm Yard Area Conservation Practices

Farm yard areas refer to disturbed surfaces used by people or vehicles (e.g., equipment 

storage yards) on at least eight calendar days per year.

Exempted operations: none 

Producers that want a Rule 403 exemption must implement at least one of the four 

conservation practices listed below. 

1. Vegetation

Establish or maintain vegetation at sufficient density to prevent wind driven dust. 

2. Dust Suppressants

Apply water or approved dust suppressants at a sufficient quantity and frequency to 

prevent wind driven dust. 

3. Surface Area Modification

Apply material with low silt content (i.e., asphalt, concrete, recycled road base, or gravel 

to a minimum depth of four inches) at sufficient quantity and frequency to prevent wind 

driven dust. 

4. Disturbed Surface Area Reduction 

Reduce farm yard area by at least 50 percent from the original disturbed surface area. To 

qualify, the original disturbed surface area must be treated (e.g., vegetation, watering that 

establishes a crust, chemical stabilization, etc.) to prevent wind driven dust. 
(8/17) 12/15/98 

Section II 

4. Track-Out Conservation Practices

Exempted operations: none 

Producers that want a Rule 403 exemption must implement at least one of the four 

conservation practices listed below. 

1. Track-Out Area Improvements

Pave or apply chemical stabilization at sufficient concentration and frequency to maintain 

a stabilized surface starting from the point of intersection with the public paved surface, 

and extending for a centerline distance of at least 100 feet with an acceptable width to 

accommodate traffic ingress and egress from the site. 

2. Track-Out Prevention

Check or clean the undercarriage and wheels on haul trucks before leaving field or install 

a track-out control device to prevent the track-out of soil onto paved public roads. 

3. End of Row Equipment Turn Around Areas

Prohibit turning tractors and implements on paved public roads if soil will be dropped on 

the road or clean pavement after practices have ceased.
(9/17) 12/15/98 

Section II 

5. Unpaved Roads Conservation Practices

Exempted operations: none 

Producers that want a Rule 403 exemption must implement at least one of the four 

conservation practices listed below. 

1. Speed Control

Control speed to 15 miles per hour (mph) on unpaved roads through worker notifications, 

signage, or any other necessary means. 

2. Access Restriction

Restrict access to private unpaved roads currently used by the public either through 

signage or physical access restrictions. 

3. Unpaved Road Treatments

Treat unpaved roads with water, mulch, chemical dust suppressants or other cover during 

heavy use periods. Unpaved farm roads should be treated early enough so that mud will 

not stick to tires and be carried onto paved public roads. 

4. Surface Modification

Cover frequently traveled unpaved roads with a low silt content material (i.e., asphalt, 

concrete, recycled road base, or gravel to a minimum depth of four inches). 
(10/18) 12/15/98 

Section II 

6. Storage Pile Conservation Practices

Exempted operations: none 

Producers that want a Rule 403 exemption must implement at least one of the four 

conservation practices listed below. 

1. Wind Sheltering

Enclose material in a three-sided barrier equal to the height of the material. Open side of 

the barrier should be oriented to the leeward (downwind) side of the material. 

2. Watering

Apply water at a sufficient quantity and frequency to prevent wind driven dust. 

3. Chemical Stabilization

Apply an approved dust suppressants at a sufficient quantity and frequency to prevent 

wind driven dust. Best for use on storage piles subject to infrequent disturbances. 

4. Covering

Install tarps, plastic, or other material as a temporary cover. Coverings should be 

anchored to prevent wind from removing the cover. 
(11/17) 12/15/98 

Section III 

Submittal Instructions for Alternative Conservation Practices 

Producers can voluntarily implement alternative conservation practices that are more 

suitable to their specific farming operations. However, producers that elect to implement 

alternative conservation practices and want to qualify for the Rule 403 exemption must 

provide a description of the alternative conservation practices to the AQMD. 

Producers that want to implement alternative conservation practices must notify the 

AQMD by August 1, 1999, or 30 days prior to starting a new farming operation. 

The notification must include a description of the alternative conservation practice(s) that 

will be implemented on-site. 

After receipt of a notification, the AQMD will consult with the Natural Resources 

Conservation Service and the applicable Resource Conservation District to determine the 

appropriateness of the alternative conservation practice(s). 

The AQMD will then notify the producer in writing if the alternative conservation 

practices are considered acceptable. Producers will be exempt from implementing 

conservation practices on the source category (e.g., active, inactive, unpaved roads, etc.) 

in which alternative conservation practices are proposed until the AQMD has notified 

said producer whether the alternative conservation practices are acceptable. If the 

alternative conservation practices are deemed unacceptable, the AQMD will notify the 

producer of such a determination and will establish a 30-day grace period to identify 

acceptable alternative conservation practices. During this 30-day grace period, the 

AQMD will work with the producer and the appropriate resource agency personnel to 

identify acceptable alternative conservation practices. 

Notifications can be mailed or delivered to: 

Rule 403 Compliance 

South Coast Air Quality Management District 

21865 East Copley Drive 

Diamond Bar, CA 91765-4182 

Notifications can also be submitted electronically to: 

mlaybourn@aqmd.gov
(12/17) 12/15/98 

Section IV 

Submittal Instructions for Justification Statements

In the event that there are special technical (e.g., non-economic) circumstances, including 

safety, which prevent implementation of the suggested minimum number of conservation 

practices within each category listed in Section II, a justification statement must be 

submitted in order for a producer to qualify for a Rule 403 exemption. 

Producers that want to submit a justification statement must notify the AQMD by August 

1, 1999, or 30 days prior to starting a new farming operation. 

The justification statement must explain the reason(s) why the suggested minimum 

number of conservation practices within a category can not be implemented on-site. 

After receipt of a justification statement, the AQMD will consult with the Natural 

Resources Conservation Service and the applicable Resource Conservation District to 

determine the appropriateness of the information submitted. 

The AQMD will then notify the producer in writing if the justification statement(s) are 

considered acceptable. Producers will be exempt from implementing conservation 

practices on the source category (e.g., active, inactive, unpaved roads, etc.) in which a 

justification statement is proposed until the AQMD has notified said producer whether 

the justification statement is acceptable. If the justification statement is deemed 

unacceptable, the AQMD will notify the producer of such a determination and will 

establish a 30-day grace period to identify any alternative conservation practices or other 

possible justification statements. During this 30-day grace period, the AQMD will work 

with the producer and the appropriate resource agency personnel to identify alternative 

conservation practices or other possible justification statements. 

Justification statements can be mailed or delivered to: 

Rule 403 Compliance 

South Coast Air Quality Management District 

21865 East Copley Drive 

Diamond Bar, CA 91765-4182 

Justification statements can also be submitted electronically to: 

mlaybourn@aqmd.gov
(13/17) 12/15/98 

Section V 

Conservation Practice Self Monitoring Form 

The following form has been prepared to assist producers in documenting 

implementation of the conservation practices. Producers are required to prepare and 

maintain this form to qualify for a Rule 403 exemption. 

A sample completed conservation practice self-monitoring form is also provided 

following the blank form. 
(14/17) 12/15/98 

 Farm Name: 

Section V  Producer Signature: 

Conservation Practice Self Monitoring Form1 Date:  Active2 Inactive2 Farm Yard Area Track-Out Unpaved R

√

Activity Modification (Mandatory)

(minimum of three) (minimum of one) (minimum of one) (minimum of 

(minimum of one from 

below) 

 Local Jurisdiction 

Ordinance 

 Vegetation Track-Out Area 

Improvements 

 Speed Control 

 Soil Moisture Cover Crop Dust Suppressants Track-Out Prevention Access Restrict Irrigation System Crop Residue 

Management 

 Surface Area 

Modification 

 End of Row Turn 

Around Areas 

 Unpaved Road 

Treatments 

 Minimum Tillage Surface Roughening Disturbed Surface 

Area Reduction 

Alternative Practices Surface Modifi

 Mulching Minimum Tillage Alternative Practices Justification Alternative Pra

Alternative Practices Cross Wind 

Stripcropping 

Justification Justification 

Justification Field Windbreaks 

 Ridge Roughness  Wind Barriers 

Alternative Practices Justification 

1 If you wish to choose different practices for different fields and/or farm areas, separate sheets must be filled out for each site. 2 The following operations are exempt from active and inactive land conservation practices: orchards, vine crops, nurseries, range land, and irrig
(15/17) 12/15/98 

 Farm Name: AAAA Farms 

Section V  Producer Signature: 

Conservation Practice Self Monitoring Form1 Date:  Active2 Inactive2 Farm Yard Area Track-Out Unpaved R

√

Activity Modification (Mandatory)

(minimum of three) (minimum of one) (minimum of one) (minimum of 

(minimum of one from 

below) √

Local Jurisdiction Ordinance 

 Vegetation 

√

Track-Out Area Improvements √

Speed Control 

 Soil Moisture Cover Crop Dust Suppressants Track-Out Prevention Access Restrict√

Irrigation System 

√

Crop Residue Management 

 Surface Area 

Modification 

 End of Row Turn 

Around Areas 

 Unpaved Road 

Treatments 

 Minimum Tillage Surface Roughening 

√

Disturbed Surface Area Reduction 

Alternative Practices Surface Modifi

 Mulching Minimum Tillage Alternative Practices Justification Alternative Pra

Alternative Practices 

√

Cross Wind Stripcropping 

Justification Justification 

Justification Field Windbreaks 

 Ridge Roughness  Wind Barriers 

Alternative Practices Justification 

1 If you wish to choose different practices for different fields and/or farm areas, separate sheets must be filled out for each site. 2 The following operations are exempt from active and inactive land conservation practices: orchards, vine crops, nurseries, range land, and irrig
(16/17) 12/15/98 

Section VI 

Opting for Rule 403 General Provisions 

AQMD in conjunction with local producers and staff from the NRCS, RCDs, and 

Cooperative Extension have developed the conservation practices contained in this 

Handbook to be more appropriate for farming operations than the traditional dust control 

requirements for construction projects, landfills, and other dust sources. 

Producers that do not voluntarily implement the conservation practices before July 1, 

1999, or within 30 days of starting a farming operation at a new site would become 

subject to the general requirements contained in AQMD Rule 403. The following is a 

general summary of the Rule 403 requirements. 

• visible emissions prohibited from crossing the site property line [Section (d)(1)] 

• at least one best available control measure must be implemented for each source 

[Section (d)(2)] 

• upwind/downwind PM10 differential prohibited from exceeding 50 μg/m3

[Section (d)(4)] 

• all track-out must be prevented or removed within one hour [Section (d)(5)] 

• any operation with more than 100 acres of disturbed surfaces must submit a fugitive 

dust control plan that specifies at least one control action and one contingency control 

action for each source category (e.g., tilling, unpaved roads, etc.). A filing fee of 

$160.60 is required with all fugitive dust control plan submittals. 

Producers that would like more information can obtain a copy of Rule 403 and the 

general Rule 403 Handbook, which details traditional best available control measures, by 

calling the AQMD at (909) 396-2000 or through the internet at: 

www.aqmd.gov
(17/17) 12/15/98 

Section VI 

Failure to Comply with Rule 403 

The intent of the AQMD is to work with producers and local resource agencies (e.g., 

NRCS, RCDs, Farm Bureaus, Cooperative Extension, etc.) to reduce dust and the 

corresponding PM10 emissions from agricultural operations through the voluntary 

implementation of good conservation practices. These emission reductions are necessary 

as part of the region’s efforts to attain State and Federal air quality standards. Failure to 

achieve compliance with the State and Federal air quality standards by the mandated 

attainment date could result in Federal action that would significantly impact our region. 

Prior to June 30, 1999, the AQMD has conducted a comprehensive outreach program to 

inform local producers of the voluntary conservation practices and options available to 

maintain a Rule 403 exemption. After July 1, 1999, failure to meet Rule 403 

requirements could subject the producer mandatory conservation class(es), required dust 

control plans, fines, or other penalties.