RULE 433. CONTROL OF PARTICULATE EMISSIONS AT OWENS LAKE

Adopted: 04/13/2016 

The purpose of this regulation is to effectuate a regulatory mechanism under the federal Clean

Air Act to attain the National Ambient Air Quality Standards (“NAAQS”) and to implement the 

Stipulated Judgment between the Great Basin Unified Air Pollution Control District (“District”)

and the City of Los Angeles (“City”) dated December 30, 2014 and entered by the Superior 

Court of the State of California, County of Sacramento. This regulation does not alter or 

supersede any provision in the Stipulated Judgment, nor does it relieve any party from full

compliance with the requirements of the Stipulated Judgment. This regulation sets the basic

requirements for the Best Available Control Measures (“BACM”) and defines the areal extent of 

these controls at Owens Lake, California required in order to meet the NAAQS. This regulation

does not preclude the City or the District from implementing more stringent or additional 

mitigation pursuant to the Stipulated Judgment. 

A. DEFINITIONS 

1. “BACM PM10 Control Areas” are areas on the dried bed of Owens Lake at or below the 

Regulatory Shoreline elevation of 3,600 feet and at or above Owens Lake’s ordinary high

water elevation of 3,553.55 feet on which BACM PM10 Control Measures shall be 

implemented, and 

BACM PM10 Control Areas are:

a. Areas, as shown on the map in Exhibit 1 – Dust Control Area Map, including: 

i. 29.8 square miles of the Owens Lake Bed with approved BACM PM10 Control 

Measures (“2003 Dust Control Area”);

ii. 13.2 square miles of the Owens Lake Bed with approved BACM PM10 Control 

Measures, except for Eligible Cultural Resource Areas where PM10 BACM

selection and implementation dates will be deferred as set forth in Paragraph C.3. 

(“2006 Dust Control Area” and “Channel Area”);

iii. 2.0 square miles of the Owens Lake Bed with approved BACM PM10 Control 

Measures (“Phase 8 Area”);

iv. 3.62 square miles of the Owens Lake Bed with approved BACM PM10 Control 

Measures to be installed by December 31, 2017, except for Eligible Cultural 

Resource Areas, where PM10 BACM selection and implementation dates will be 

deferred as set forth in Paragraph C.3. (“Phase 9/10 Area”); and

b. Additional areas as designated pursuant to Section C., “CONTINGENCY

MEASURES” of this rule.

2. “BACM PM10 Control Measures” are best available control measures designed to reduce 

PM10 emissions to Control Efficiency (“CE”) levels specified below through compliance

Rule 433
with performance standards specified in Attachment A or in specific control measure

definitions below. The following BACM PM10 Control Measures are approved to be 

used. 

a. “BACM Shallow Flooding” means the application of water to the surface of the lake

bed in accordance with the performance standards for shallow flooding in Attachment

A, Section I - Performance Requirements for BACM Shallow Flooding. Water shall

be applied in amounts and by means sufficient to meet a CE level of 99% or CE

targets for Minimum Dust Control Efficiency Areas. 

b. “Tillage with BACM (Shallow Flood) Backup or TWB2” means the roughening of a 

soil surface using mechanical methods in accordance with the specifications in

Attachment A, Section IV – Performance Requirements for Tillage with BACM

Back-up, and to utilize BACM shallow flooding as a back-up control method in order 

to prevent NAAQS violations. BACM Shallow Flooding must be implemented in

TWB2 areas if the erosion threshold as defined in Paragraph A.2.h is exceeded. Water

shall be applied in amounts and by means sufficient to meet the CE level of 99% or 

CE targets for Minimum Dust Control Efficiency areas. 

c. “Brine BACM” means the application of brine and the creation of wet and/or nonemissive salt deposits sufficient to meet the CE level of 99% as described in

Attachment A, Section V – Performance Requirements for Brine BACM. BACM

Shallow Flooding must be implemented in Brine BACM areas if the erosion threshold 

as defined in Paragraph A.2.h is exceeded.

d. “BACM Managed Vegetation” means planting surfaces of the BACM PM10 Control 

Areas with protective vegetation to meet the CE level of 99% by maintaining overall 

average vegetation cover of at least 37% for each contiguous Managed Vegetation

area and an areal distribution based on vegetation cover thresholds and grid size. 

e. “BACM Gravel Blanket” means the application of a layer of gravel sufficient to meet

the CE level of 100% by covering the control area with

• a layer of gravel at least four inches thick with gravel screened to a size greater

than 1⁄2 inch in diameter, or 

• a layer of gravel at least two inches thick with gravel screened to 1⁄2 inch in

diameter underlain with a permanent permeable geotextile fabric. 

f. “Dynamic Water Management or DWM” is a BACM Shallow Flooding operational

modification that allows delayed start dates and/or earlier end dates required for

shallow flooding in specific areas that have historically had low PM10 emissions 

within the modified time periods. The truncated dust control periods allows for water

savings while achieving the required CE level. Areas eligible for the DWM program 

and their modified start and/or end dates for shallow flooding are identified in

Rule 433
Attachment A, Section VI – Performance Requirements for Dynamic Water

Management. If any DWM area becomes susceptible to wind erosion outside of the 

modified dust control period the area will be required to be flooded to meet the 

required CE for that area. BACM Shallow Flooding must be implemented in DWM

areas if the erosion threshold as defined in Paragraph A.2.h is exceeded.

g. “Minimum Dust Control Efficiency or MDCE” BACM is a dust control measure for

which the control efficiency target is adjusted to match the required control level

based on air quality modeling for the 2006 dust control areas as shown on the map in

Exhibit 2 – Dust Control Efficiency Requirements. The control efficiency targets

may be less than 99%, but the level of control in all areas is intended to prevent 

exceedances of the NAAQS. MDCE BACM includes: 

i. Shallow flood areas where the wetness cover is adjusted following the curve in

Exhibit 3 - Shallow Flood Control Efficiency and Wetness Cover Curve, 

ii. Channel Area - a state-regulated wetland area as shown in Exhibits 1 and 2 where

vegetation cover is enhanced by irrigation and seeding with native plants in a 

manner sufficient to prevent windblown dust from causing exceedances of the 

NAAQS, and

iii. Sand Fence Area – an area as shown in Exhibits 1 and 2 located in area T1A-1 

where sand fences, vegetation and natural water runoff combine to provide 

sufficient protection to prevent windblown dust from causing exceedances of the 

NAAQS.

h. “Erosion Threshold” is applicable to TWB2

, DWM, and Brine BACM to trigger

BACM Shallow Flooding which must be implemented to comply with the shallow 

flood CE target for that area. The erosion threshold is determined from sand flux

measurements or the Induced Particulate Erosion Test (IPET) test method as

described in Attachment A, Paragraphs IV.C.2 and IV.C.4. BACM Shallow Flooding 

must be implemented in TWB2

, DWM or Brine BACM areas if any of the following 

thresholds are exceeded as determined using the methods described in Attachment A: 

i. Sand flux measured at 15 cm above the surface exceeds 5.0 grams per square

centimeter per day on DWM or Brine BACM areas or 1.0 gram per square 

centimeter per day on TWB2 areas, or 

ii. Induced Particulate Erosion Test method shows visible dust emissions when

operated at the reference test height. 

i. “Approved BACM” includes the control measures specified above and other

measures approved by the APCO and the US Environmental Protection Agency as

equivalent to these methods. 

Rule 433
3. “Eligible Cultural Resource Area or ECR Area” is an area or areas where dust control 

measures will be implemented on a deferred schedule due to the presence of significant

cultural resources that make the areas eligible for listing under the California Register of

Historic Resources. 

B. REQUIREMENTS

1. For the 2003 Dust Control Area the City shall continuously operate and maintain any mix

of approved BACM PM10 Control Measures as defined above in Section A to meet the 

99% efficient CE level. Selection of the type and location of BACM PM10 Control 

Measures within the area is solely the responsibility of the City.

2. For the 2006 Dust Control Area the City shall continuously operate and maintain

approved BACM PM10 Control Measures defined above in Section A to meet the CE

target specified in Exhibit 2, except for ECR Areas where BACM PM10 Control Measure

selection and implementation dates will be deferred as set forth in Paragraph C.3., and

any areas of BACM Managed Vegetation, for which the City shall comply with the 

minimum 37% average vegetation cover target and areal distribution requirements by

December 31, 2017. 

3. For the Phase 8 Area consisting of 2.0 square miles the City shall continue to operate and

maintain BACM Gravel Blanket. 

4. For the Phase 9/10 Project Area consisting of 3.62 square miles the City shall select and

install BACM PM10 Control Measures by December 31, 2017, except for ECR Areas,

where PM10 BACM selection and implementation dates will be deferred as set forth in

Paragraph C.3. 

5. In areas containing infrastructure capable of achieving and maintaining compliant BACM

Shallow Flooding the City may implement TWB2, Brine Shallow Flooding or Dynamic

Water Management as alternatives to BACM Shallow Flooding or MDCE BACM

shallow flooding. 

C. CONTINGENCY MEASURES

1. At least once each calendar year, the District shall determine whether additional areas of 

the lake bed require BACM PM10 Control Measures in order to attain or maintain the 

PM10 NAAQS. 

2. If the District has not demonstrated attainment with the PM10 NAAQS on or before 

December 31, 2017, or has not met reasonable further progress milestones, the District

shall order the City to apply one or more BACM PM10 Control Measures as set forth in

Rule 433
Paragraphs A.2 and C.4 on those areas of the Owens Lake bed that cause or contribute to

exceedances of the PM10 NAAQS. 

3. If monitoring and/or modeling demonstrates BACM PM10 Control Measures are needed

in an ECR Area(s) to attain or maintain the PM10 NAAQS after BACM PM10 Control 

Measures are implemented in adjacent areas, the District shall order the City to select and

implement BACM PM10 Control Measures set forth in Paragraph A.2. 

4. The District may order the City to implement, operate and maintain a total of up to 53.4 

square miles of waterless or water-neutral BACM PM10 Control Measures on the Owens

Lake bed below the Regulatory Shoreline (elev. 3,600 feet) and above the ordinary high

water level of Owens Lake (elev. 3,553.55 feet).

5. As expeditiously as practicable and not more than three years after any such order for

additional BACM PM10 Control Measures, the City shall install, operate and maintain

BACM PM10 Control Measures that achieve a control efficiency of 99%. If BACM

Managed Vegetation is chosen up to two additional years for vegetation growth is

allowed to achieve the 37% vegetation cover requirement.

EXHIBIT 1 – Dust Control Area Map

EXHIBIT 2 – Dust Control Efficiency Requirements 

EXHIBIT 3 – Shallow Flood Control Efficiency and Wetness Cover Curve 

ATTACHMENT A – Performance Requirements for BACM 

Rule 433
Great Basin Unified Air Pollution Control District

Exhibit 1 - PM10 Dust Control Areas T2-1 Addition

T1A-2

T10-1

T10-2

T17-2

T18-0

T21

T1A-1

T1A-4

T12-1

T3NE

T3SE

T3SW T4-3

T28N

T27N T28S

T27S T26

T24 T25N

T25S

T23E

T23W

T35-1

T35-2

T36-1

T36-2

T36-3

T29-4

T18N

T18S

T11 T13-3 T13-2

T9

T1-1 T2-5

T2-4

T2-3

T2-2

T5-1

T2-1

T29-1

T30-3

T29-2

T29-3

T30-1

T30-2

T5-3

T8W

T4-5

T4-4

T16

T23-5

T25-3

T8

T7

T6

T5

C2

C1

T10-3

T17-1

Area A

T32-1

T37-2

T1A-3

T37-1

T10-3-L1

T21-L1

T21-L2

T32-1-L1

T21-L3

T13-1

T5-1 Add

T5-3 Add

T36-3 Add

T18N Add

Corridor 1

T27 Add

T24 Add

T5-2

T3SE Add

T4-3 Add

T5-4

T13-1 Add

Area B

C2-L1

DuckPond-L1

T10-L1

T17-2-L1

T35-2-L1

T37-1-L1

T37-2-L1

T37-2-L4

T37-2-L2

T37-2-L3

T21-L4

DuckPond-L2

T9

Keeler

Dunes

Owens Lake ordinary

high water

elevation: 3553.55'

410000

410000

415000

415000

420000

420000

425000

425000

430000

430000

40200004020000

40250004025000

40300004030000

40350004035000

40400004040000

40450004045000

 3/9/2016 1:08:16 PM SIP Revision 2016 Exhibit 1 Dust Control Map 20160309 rule 433.mxd

Regulatory Shoreline: 3600'

Ordinary High Water Elevation

Keeler Dunes Control Area

Dust Controls

2003 Dust Control Area: 29.8 sq mi

2006 Dust Control Area: 12.7 sq mi

Channel Area: 0.5 sq mi

Phase 8 Area: 2.0 sq mi

Phase 9/10 Area: 3.62 sq mi

Owens

Lake

California Arizona

Idaho

Montana

Nevada

Oregon

Utah

Washington

Location Map:

0 1 2

Miles

É

UTM:

UTM:
Great Basin Unified Air Pollution Control District

Exhibit 2 - Dust Control Efficiency Map 

98

0

0

0

53

63

63

63

66

72

79

81

84

85

91

92

95

95

97

98

98

T1A-2_b

T1A-1

T23-5

T25-3

Channel 2

Channel 1

Keeler

Dunes Dust

Control Area

Owens

Lake

Legend:

DCAs with Minimum Dust Control Efficiency

 3600' Shoreline

Control Efficiency

MDCE / Keeler Dunes

85% - Keeler Dunes

99% - SF, Man Veg, TWB2, Brine, Hybrid

100% - Gravel

0 1 2

Miles

É

 2/2/2016 3:40:27 PM SIP Revision 2016 Exhibit 2 Control Efficiency 201602202.mxd

Rule 433 - Exhibit 2
Exhibit 3 - Shallow Flood control efficiency curve

Percent Water Cover

0 10 20 30 40 50 60 70 80 90 100

Percent Efficiency

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

42

44

46

48

50

52

54

56

58

60

62

64

66

68

70

72

74

76

78

80

82

84

86

88

90

92

94

96

98

100

Rule 433 - Exhibit 3
Rule 433 – Attachment A

Rule 433 – Attachment A 

Performance Requirements for BACM 

I. BACM Shallow Flooding

A. The “BACM Shallow Flooding” PM10 control measure will apply water to the surface of 

those areas of the lake bed where shallow flooding is used as a PM10 control measure. 

Water shall be applied in amounts and by means sufficient to achieve the performance 

standards set forth in Paragraphs I.B and I.C of this attachment. The dates by which 

BACM Shallow Flooding areas are to comply with these performance standards may be 

modified by the Dynamic Water Management provisions set forth in Rule 433.A.2.f and 

Paragraph VI.B. 

B. For all BACM Shallow Flooding areas except those within the 2006 DCA:

1. At least 75 percent of each square mile designated as BACM Shallow Flooding areas

shall continuously consist of standing water or surface-saturated soil, substantially 

evenly distributed for the period commencing on October 16 of each year, and ending 

on May 15 of the next year. For these BACM Shallow Flood dust control areas, 75 

percent of each entire contiguous area shall consist of substantially evenly distributed 

standing water or surface- saturated soil. 

2. Beginning May 16 and through May 31 of every year, shallow flooding areal 

wetness cover may be reduced to a minimum of 70 percent. 

3. Beginning June 1 and through June 15 of every year, shallow flooding areal 

wetness cover may be reduced to a minimum of 65 percent. 

4. Beginning June 16 and through June 30 of every year, shallow flooding areal 

wetness cover may be reduced to a minimum of 60 percent. 

C. For BACM Shallow Flooding areas within the 12.7 square-mile 2006 DCA:

1. The percentage of each area that must have substantially evenly distributed 

standing water or surface-saturated soil shall be based on the Shallow Flood 

Control Efficiency Curve (Exhibit 3) to achieve the control efficiency levels in the

Minimum Dust Control Efficiency (MDCE) Map (Exhibit 2). 

2. For only those BACM Shallow Flooding areas with control efficiencies of 99 percent 

or more:

a. Beginning May 16 and through May 31 of every year, shallow flooding 

areal wetness cover may be reduced to a minimum of 70 percent. 
Rule 433 – Attachment A

b. Beginning June 1 and through June 15 of every year, shallow flooding areal 

wetness cover may be reduced to a minimum of 65 percent. 

c. Beginning June 16 and through June 30 of every year, shallow flooding 

areal wetness cover may be reduced to a minimum of 60 percent.

II. BACM Managed Vegetation

The “BACM Managed Vegetation” PM10 control measure requires planting surfaces of the 

BACM PM10 control areas with protective vegetation to meet the control efficiency level of 

99% by maintaining an overall average vegetation cover of 37% for each contiguous 

managed vegetation area.

III. BACM Gravel Blanket

The BACM Gravel Blanket” PM10 control measure requires the application of a layer of 

gravel sufficient to meet the control efficiency level of 100% by one of the following 

means:

• covering 100% of the control area with a layer of gravel at least four inches thick 

with gravel screened to a size greater than 1⁄2 inch in diameter, or

• covering 100% of the control area with a layer of gravel at least two inches thick 

with gravel screened to 1⁄2 inch in diameter underlain with a permanent permeable 

geotextile fabric.

IV. Tillage with BACM (Shallow Flood) Backup (or TWB2)

A. The City of Los Angeles (“City”) may implement or transition BACM Shallow Flood 

areas to “Tillage with BACM (Shallow Flood) Back-up (TWB2

),” which shall consist of

(1) soil tilling within all or portions of BACM Shallow Flood PM10 control areas (TWB2

Areas), and (2) the installation of all necessary shallow flood infrastructure so that the

TWB2 Areas can be shallow-flooded if the erosion threshold is exceeded or the 

performance criteria are not met.

B. Construction of TWB2 Areas

1. Tillage shall create rows and furrows in roughly east to west directions in order to 

create maximum surface roughness for winds from the north and south. Additional 

roughness to protect surfaces from west winds shall be created in tilled areas 
Rule 433 – Attachment A

sufficient to prevent emissions from east and west winds. 

2. The tilled surfaces will also be armored with soil clods of 1/2 inch diameter or 

larger covering 60 percent or more of the tilled surface. 

3. TWB2 areas shall be constructed with ridge heights (RH) averaged on 40-acre blocks 

at or above 1.25 feet (furrow depth to ridge top difference at least 2.5 feet) and row 

spacing (RS) sufficient to provide a ratio of the row spacing to ridge height (RS/RH)

below 10, e.g. distance between rows is 12.5 feet with average ridge height greater 

than 1.25 feet.

C. Monitoring and Maintenance

1. Surface Roughness

a. Lidar, aerial photography or other field measurement methods with equivalent 

accuracies will be used by the City to measure RS/RH ratio and ridge height. 

Roughness measurements will be made in the north-to-south direction --- the 

direction of the primary dust producing winds. Roughness measurements may 

also be made in other directions. Roughness measurements will be reported to the

APCO within 30 days of measurement. 

b. The RS/RH ratio and ridge height measurements will be made at 6 month, or 

more frequent, intervals. Inverse roughness and ridge height for a TwB2

 Area 

will be tracked and plotted as a function of time. Where feasible, field 

measurements may also be taken to confirm Lidar or other remotely sensed 

results. The City will conduct roughness measurements at least once every 6 

months and report the measurements within 30 days to the APCO. The District 

reserves the right to conduct its own roughness measurements at any time. 

c. Assuming that degradation of the tilled ridges may occur over time, tillage 

maintenance will be performed by the City if the average RS/RH roughness ratio

is between 10.1 and 12.0 or if the average ridge height is less than 1.1 feet in a

tilled area. 

d. The City shall re-flood a TWB2 area to comply with the required BACM Shallow

Flood control efficiency for the area if the RS/RH ratio is greater than 12.0 (12/1)

or the ridge height falls below 1.0 feet for any defined 40-acre averaging area. 

e. The City shall measure clod coverage using the point-intercept method (U.S. 

Bureau of Land Management, Sampling Vegetation Attributes, Method G, 
Rule 433 – Attachment A

Technical Reference BLM/RS/ST-96/002+1730) or other field measurement 

methods with equivalent accuracy. Clod cover will be measured concurrently 

with surface roughness at least once every 6 months and reported to the APCO 

within 30 days of measurement. 

2. Sand Flux

a. The City shall monitor each TWB2 area with at least four Sensits and Cox sand 

catchers (CSCs) with inlets set at 15 cm above untilled surfaces (circular pads 

with 3 m radius) in the general northern, southern, eastern and western portions 

of a tillage. In TWB2 areas greater than 320 acres the City shall install one 

Sensit and CSC pair per 80 acres.

b. The City will pair CSCs with Sensits, radio equipment and dataloggers 

programmed to record 5-minute sand motion data. All Sensit data will be

reported daily to the District. Sand motion data from the CSCs and Sensits will 

be processed to track sand flux at each site.

c. All sand flux monitoring equipment will be installed prior to the start of 

tillage activities.

d. High sand flux values recorded during maintenance activities or from non-tillage 

sand flux sources shall be excluded from the sand flux data. Maintenance 

activities and non-tillage sand flux sources may include, but are not limited to, 

rain-splatters, bugs, adjacent grading and road construction activities, as well as 

vehicle traffic. Sensits should be placed so as to minimize impacts from nontillage sand flux sources.

e. When (other than during maintenance activities taking place in the “tillage area” 

which is defined as the tilled portion of the TWB2 area) the sand flux exceeds 

0.50 g/cm2

/day, the City will perform maintenance in the tillage area, which may 

include surface wetting, re-establishment of the surface roughness, or full or 

partial reflooding of a TWB2

. 

3. PM10 Monitoring

a. Each TWB2 area will be assigned upwind and downwind PM10 monitors (not 

necessarily at the TwB2

 Area boundary) to monitor PM10 emissions from the 

tillage area. For a given wind direction, the downwind monitors shall be within 
Rule 433 – Attachment A

22 degrees (±11.5°) of the upwind monitors. Upwind/downwind monitor 

assignments will be requested by the City and approved by the APCO. Existing 

monitors operated by the District may be used as upwind/downwind monitors. 

Additional EPA reference and equivalent method PM10 monitors (40 CFR Part 

53) shall be operated by the City, unless mutually agreed otherwise. 

b. If a monitor is operated by the City, its operation and maintenance must follow 

District procedures and data collection must be incorporated into the District 

communications network. The District reserves the right to audit monitors and 

monitoring data collected by the City. The District also reserves the right to

install and operate or require the City to install and operate additional PM10

monitors to adequately monitor the PM10 emissions coming from tilled areas.

c. All PM10 monitoring equipment will be in place as soon as practicable as shallow

flood areas dry, but no later than the start of tillage activities.

d. Impacts caused by maintenance activities and non-tillage sources shall be

excluded from the PM10 data. Maintenance activities and non-tillage PM10 

sources may include, but are not limited to, adjacent grading and road 

construction activities, as well as vehicle traffic. PM10 monitors should be 

placed so as to minimize impacts from non-tillage sources.

e. When the daily downwind to upwind PM10 concentration difference for any dust 

event (other than during maintenance activities in the tillage area) exceeds 50 

μg/m3 and there is no evidence to show that the additional downwind PM10 did 

not come from the TWB2

 Area, maintenance will be performed in the tillage 

area. 

4. Induced Particulate Erosion Test

a. The Induced Particulate Erosion Test (IPET) method will be used to determine if 

tilled area surfaces are starting to become emissive. The IPET method uses a 

small radio-controlled helicopter-type craft (Radio-Controlled Wind Induction 

Device or RCWInD) to create wind on the surface. Each RCWInD craft shall be

pre-tested to determine the test height above the surface (Ht) at which the craft 

creates a target maximum horizontal wind speed (TWS) measured at 1 centimeter 

(U0.01) above a flat surface equal to 11.3 meters per second (m/s). If the payload 

on a craft is changed, e.g. a different camera is used, then Ht must be re-
Rule 433 – Attachment A

determined for the new payload since it will affect the amount of thrust needed to 

keep the RCWInD aloft.

b. Testing to determine Ht and TWS will be done on a smooth flat surface, e.g. 

concrete or asphalt pavement or plywood test platform with calm ambient winds 

(< 2 m/s). Ht is measured from the bottom of the rotor blade to the surface. The

maximum wind speed for any flight height is taken at a height one centimeter 

above the surface at a point that is one rotor blade length away from the point 

beneath the center of the fastest rotor blade taken on a line extending outward 

from the rotor arm. The wind speed measurement is taken with a pitot tube

pointing toward the center of the rotor blade. The RCWInD must be flown in a 

stationary position to get a sustained wind speed measurement.

c. When the craft is flown over a ridged surface Ht is measured from the bottom of 

the craft’s rotor blades to the highest surface projection anywhere directly 

below the craft.

d. Three erosion alert levels are set using the IPET method: 1) an early warning of 

possible clod and surface stability deterioration, 2) a warning level to alert the

City of a potential breakdown of the surface stability and to advise voluntary 

maintenance efforts, and 3) a mitigation action level to require re-tilling and/or 

re-flooding of all or part of a TWB2, DWM or Brine BACM Area.

e. The IPET method will be used to determine erosion alert levels as follows: 

• Level 1 – An erosion early warning is indicated when any visible dust is 

observed to be emitted from a surface or particles are dislodged when the 

RCWInD is flown at a height below one half of Ht. Voluntary mitigation may 

be appropriate to prevent further surface degradation.

• Level 2 – An erosion warning is indicated when any visible dust is observed 

to be emitted from a surface when the RCWInD is flown at a height below Ht 

and above one half of Ht. Voluntary mitigation is advised to prevent further 

surface degradation. 

• Level 3 – Mitigation action is required if visible dust is observed to be 

emitted from a surface when the RCWInD is flown at a height of Ht or 

higher.

D. The City shall re-flood TwB2 areas to comply with the BACM Shallow Flood control 
Rule 433 – Attachment A

efficiency target for that area, if either of the following erosion thresholds are exceeded 

as determined using the sand flux and IPET measurements described in Paragraphs 

IV.C.2 and IV.C.4. 

1. Sand flux measured at 15 cm above the surface exceeds 1.0 gram per square 

centimeter per day, or

2. Induced Particulate Erosion Test method shows visible dust emissions when 

operated at the reference test height, Ht. 

V. Brine BACM

A. Stable surfaces for Brine BACM shall be defined as consisting of standing water, 

evaporite salt deposit, and capillary brine salt crust as follows:

1. Water: Standing water or hydrologically saturated surface as defined by BACM

Shallow Flooding, regardless of salinity level. 

2. Evaporite Salt Deposit: A crystalline deposit of salt minerals precipitated on the 

surface of the lakebed from evaporation of Owens Lake brine. The evaporite salt 

deposit does not include the development of salt crust by upward capillary 

movement of saline fluids through the soil column. The evaporite salt deposit 

must have an average thickness of 1.5 centimeters or greater and may be either wet 

or dry. 

3. Capillary Brine Salt Crust: A crust enriched in salt minerals formed at the soil 

surface by upward capillary movement of water through the soil. The capillary brine 

crust typically consists of a mix of salt minerals and soil particles in various 

proportions, and must meet the following three conditions: 

a. The capillary brine salt crust within a Brine BACM area must have an 

average thickness of 10 centimeters or greater and may be either wet or dry, 

b. a capillary brine salt crust must be accompanied by either water and/or an 

evaporite salt deposit, and

c. the proportion of qualifying capillary brine crust within a Brine BACM area 

cannot exceed one-third of the required total compliant cover within a Brine

BACM area.

B. Each Brine BACM area shall be operated such that the total areal extent of the surface 

cover of the qualifying surfaces are maintained such that they meet or exceed those as 
Rule 433 – Attachment A

defined by the Shallow Flooding Control Efficiency Curve in Exhibit 3. The combined 

mosaic of stable Brine BACM surfaces shall cover the entire dust control area. 

C. Brine BACM can be used by the City of Los Angeles (City) throughout the Owens Lake 

bed where backup BACM Shallow Flood infrastructure exists and can be implemented, 

as set forth in this protocol, to ensure that Brine BACM areas do not cause or contribute

to exceedance of the NAAQS for PM10. 

D. The boundaries for each Brine BACM area will be pre-defined by the City prior 

to implementation. Each Brine BACM area will be monitored separately to 

determine compliance with required surface cover conditions. 

E. The City will monitor each Brine BACM area with at least one sand flux monitor 

(SFM) site instrumented with paired Cox Sand Catchers (CSCs) and Sensits with 

inlets positioned 15 cm above the surface, radio equipment, and dataloggers 

programmed to record 5-minute sand motion data. SFM sites will primarily be 

located in portions of Brine BACM areas covered with a capillary crust. All Sensit 

data will be reported daily to the District. Sand motion data from the CSCs and 

Sensits will be processed to track sand flux at each site.

F. Brine BACM areas will be monitored using the IPET method following the procedures 

used for Tillage with BACM Back-up areas in Paragraph IV.C.4. 

G. The City shall re-flood Brine BACM areas to comply with the BACM Shallow Flood 

control efficiency target for that area, if either of the following erosion thresholds are 

exceeded as determined using the sand flux and IPET measurements described in 

Paragraphs IV.C.2 and IV.C.4. 

1. Sand flux measured at 15 cm above the surface exceeds 5.0 grams per square 

centimeter per day, or

2. Induced Particulate Erosion Test method shows visible dust emissions when 

operated at the reference test height, Ht.

VI. Dynamic Water Management

A. Areas that are eligible for Dynamic Water Management (DWM) must meet the

following sand flux history criteria: 

1. 5 years or more of sand flux data from before dust control implementation, 

and
Rule 433 – Attachment A

2. The frequency of significant sand flux (>5 g/cm2/day) taking place outside of the 

modified shallow flood dust control period did not occur in more than one calendar 

year over any continuous six year period. 

B. The modified dust seasons for DWM have three different start dates in the beginning of

the season that reflect the delayed start of source area activity across the lakebed. The 

modified start dates are applicable to certain dust control areas based on the sand flux 

history as evaluated in Paragraph VI.A and the method of shallow flooding using

conventional flooding or sprinkler irrigation. 

1. For areas shallow flooded by methods other than sprinkler irrigation, the standard 

and modified dust control periods are: 

Standard Dust Season

October 16 to June 30 (with ramping of 99% control areas after May 15)

Modified Dust Seasons for Dynamic Water Management

October 16 – April 30

December 1 – April 30

January 16 – April 30

2. For eligible areas that are shallow flooded with sprinkler irrigation, the modified 

DWM seasons shall be adjusted to provide water two weeks earlier in the beginning 

of the dust season to simulate ramp up as applied in conventional BACM Shallow 

Flood areas and one month later at the end of the dust season due to the lack of 

wetness during the dry down period with conventional BACM Shallow Flood areas. 

The adjustments to the DWM seasons for sprinkler irrigated shallow flooding areas 

are provided below.

Modified Dust Seasons Adjusted for Sprinkler Irrigated Shallow Flooding Areas

October 16 – May 31

November 16 – May 31

January 1 – May 31

3. In areas approved for DWM, the City of Los Angeles (City) shall meet the shallow 

flood control efficiency and wetness targets indicated in Exhibits 2 and 3 by or 

before the applicable start dates in Paragraph VI.B and water may be shut off with no 

spring ramping at the end of the modified season.

C. Each DWM area will be instrumented by the City with sand flux monitoring (SFM) sites 
Rule 433 – Attachment A

using paired Sensits and Cox Sand Catchers (CSCs) during the modified start and end 

periods. The locations of SFM sites shall be determined by the City in coordination with 

the District.

1. The number of SFM sites at the modified start of the dust season will be proportional 

to the areal extent of the DWM area. All DWM areas will require at least one SFM 

site however; the APCO may require proportionally more SFM sites for DWM areas 

greater than 320 acres such that there is approximately one SFM site per 160 acres of 

DWM area.

2. During the modified end period of the dust season, the LADWP shall install SFM 

sites incrementally in stages as a DWM area dries. The number of SFM sites is

provided in Table 1 below.

Table 1. Number of SFM sites required per DWM area during the 

modified end of the dust season.

Drying Stage Exposed Lakebed Number of SFM sites

1 Less than 50 acres 0

2 50 – 160 acres 1

3 >160 acres 1 per every 160 acres

3. The City will pair CSCs with Sensits with inlets positioned at 15 cm above the 

surface, radio equipment and dataloggers programmed to record 5-minute sand 

motion data. All Sensit data will be reported daily to the District. Sand motion data

from the CSCs and Sensits will be processed to track sand flux at each site.

4. During the modified start of the dust season all sand flux monitoring equipment will 

be placed by the City no later than October 16. During the modified end of the dust 

season all SFM sites will be placed by the City within 7 calendar days of reaching 

each drying stage. The City shall inform the District of all SFM site installations 

within 7 days of installation. 

5. SFM sites installed for monitoring in the modified beginning dust season may be 

removed from a DWM area once the modified dust season has started for each 

DWM area or once the site location is endanger of getting flooded. The City shall 

inform the District of all SFM site removals within 7 calendar days of their removal 
Rule 433 – Attachment A

date. SFM sites installed for monitoring of the modified end of the dust season may 

be removed from a DWM area after June 30. 

D. DWM areas will be monitored using the IPET method following the procedures used 

for Tillage with BACM Back-up areas in Paragraph IV.C.4. 

E. The City shall re-flood a DWM area or sub-area as indicated by the available

information to comply with the BACM Shallow Flood control efficiency target for that 

area, if either of the following erosion thresholds are exceeded as determined using the

sand flux and IPET measurements described in Paragraphs IV.C.2 and IV.C.4. 

1. Sand flux measured at 15 cm above the surface exceeds 5.0 grams per square 

centimeter per day, or

2. Induced Particulate Erosion Test method shows visible dust emissions when 

operated at the reference test height, Ht.

F. If any DWM area exceeds either erosion threshold in Paragraph VI.E in more than one 

calendar year over any continuous six-year period, that area will revert to the standard 

BACM Shallow Flood dust season as shown in Paragraph VI.B.1 since the area will no 

longer meet the DWM criteria in Paragraph VI.A.