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Appendix G – Buffer Guidance.

The purpose of this guidance is to assist you in complying with the requirements in Part 2.1.2.1 of 

the permit regarding the establishment of natural buffers or equivalent sediment controls. This 

guidance is organized as follows:

G.1 SITES THAT ARE REQUIRED TO COMPLY WITH PART 2.1.2.1.........................................................2

G.1.1 Step 1 - Determine if Your Site is Within 50 Feet of a Surface Water .................................2

G.1.2 Step 2 - Determine if Any Exceptions to the Requirements in Part 2.1.2.1 Apply............3

G.2 COMPLIANCE ALTERNATIVES GUIDANCE....................................................................................4

G.2.1 Guidance for Providing and Maintaining Natural Buffers ..................................................4

G.2.1.1 Buffer Width Measurement.......................................................................................................5

G.2.1.2 Limits to Disturbance Within the Buffer.............................................................................7

G.2.1.3 Discharges to the Buffer............................................................................................................7

G.2.1.4 SWPPP Documentation.............................................................................................................8

G.2.2 Guidance for Providing the Equivalent Sediment Reduction as the 50-foot Buffer ........8

G.2.2.1 Determine Whether it is Feasible to Provide a Reduced Buffer ........................................8

G.2.2.2 Design Controls That Provide Equivalent Sediment Reduction as 50-foot Buffer ..........8

a. Step 1 - Estimate the Sediment Reduction from the 50-foot Buffer..............................10

b. Step 2 - Design Controls That Match the Sediment Removal Efficiency of the 50-

foot Buffer............................................................................................................................................11

G.2.3 Small Residential Lot Compliance Alternatives.................................................................12

G.2.3.1 Step 1 – Determine if You are Eligible for the Small Residential Lot Compliance 

Alternatives..............................................................................................................................................13

G.2.3.2 Step 2 – Implement the Requirements of the Small Residential Lot Compliance 

Alternative Selected..............................................................................................................................13

a. Small Residential Lot Compliance Alternative 1 ..............................................................13

b. Small Residential Lot Compliance Alternative 2 ..............................................................14
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G.1 SITES THAT ARE REQUIRED TO COMPLY WITH PART 2.1.2.1

The purpose of this part is to help you determine if the requirements in Part 2.1.2.1 apply to your 

site. 

G.1.1 Step 1 - Determine if Your Site is Within 50 Feet of a Surface Water

Part 2.1.2.1 applies to you only if your earth-disturbing activities will occur within 50 feet of 

a surface water that receives stormwater discharges from your site. Figure G – 1 illustrates

when a site would be required to comply with the requirements in Part 2.1.2.1 due to their 

proximity to a surface water. If the surface water is not located within 50 feet of the 

earth-disturbing activities, Part 2.1.2.1 does not apply. 

Figure G - 1. Example of earth-disturbing activities within 50 feet of a surface water.

If you determine that your earth-disturbing activities will occur within 50 feet of a surface 

water that receives stormwater discharges from your site, the requirements in Part 2.1.2.1 

apply, except for certain circumstances that are described in Step 2.

Note that where some natural buffer exists but portions of the area within 50 feet of the 

surface water are occupied by preexisting development disturbances, or if a portion of 

area within 50 feet of the surface water is owned by another party and is not under your 

control, the buffer requirements in Part 2.1.2.1 still apply, but with some allowances. 

Clarity about how to implement the compliance alternatives for these situations is 

provided in G.2.1.2 and G.2.2.2 below.
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Note that EPA does not consider designed stormwater control features (e.g., stormwater 

conveyance channels, storm drain inlets, stormwater basins) that direct storm water to 

surface waters more than 50 feet from the disturbance to constitute surface waters for 

the purposes of determining if the buffer requirements apply.

G.1.2 Step 2 - Determine if Any Exceptions to the Requirements in Part 2.1.2.1 Apply

The following exceptions apply to the requirements in Part 2.1.2.1:

 If there is no discharge of stormwater to surface waters through the area 

between the disturbed portions of the site and any surface waters located within 

50 feet of your site, you are not required to comply with the requirements in this 

Part. This includes situations where you have implemented controls measures, 

such as a berm or other barrier, that will prevent such discharges. 

 Where no natural buffer exists due to preexisting development disturbances (e.g., 

structures, impervious surfaces) that occurred prior to the initiation of planning for 

the current development of the site, you are not required to comply with the 

requirements in this Part. 

Where some natural buffer exists but portions of the area within 50 feet of the 

surface water are occupied by preexisting development disturbances, you are

required to comply with the requirements in this Part. For the purposes of 

calculating the sediment load reduction for either compliance alternative 2 or 3 

below, you are not expected to compensate for the reduction in buffer function 

that would have resulted from the area covered by these preexisting 

disturbances. Clarity about how to implement the compliance alternatives for 

these situations is provided in G.2.1.2 and G.2.2.2 below.

If during your project, you will disturb any portion of these preexisting 

disturbances, the area removed will be deducted from the area treated as 

natural buffer. 

 For “linear construction projects” (see Appendix A), you are not required to 

comply with this requirement if site constraints (e.g., limited right-of-way) prevent 

you from complying with the requirements of the alternatives in Part 2.1.2.1a, 

provided that, to the extent practicable, you limit disturbances within 50 feet of 

the surface water and/or you provide supplemental erosion and sediment 

controls to treat stormwater discharges from earth disturbances within 50 feet of 

the surface water. You must also document in your SWPPP your rationale for why 

it is infeasible for you to comply with the requirements in Part 2.1.2.1a, and 

describe any buffer width retained and/or supplemental erosion and sediment 

controls installed. 

 For “small residential lot” construction (i.e., a lot being developed for residential 

purposes that will disturb less than 1 acre of land, but is part of a larger residential 

project that will ultimately disturb greater than or equal to 1 acre), you have the 

option of complying with the requirements in Part G.2.3 of this appendix.

 The following disturbances within 50 feet of a surface water are exempt from the 

requirements in this Part:

- Construction approved under a CWA Section 404 permit; or
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- Construction of a water-dependent structure or water access areas (e.g., 

pier, boat ramp, trail). 

Note that you must document in your SWPPP if any disturbances related to any of the 

above exceptions occurs within the buffer area on your site. 

G.2 COMPLIANCE ALTERNATIVES GUIDANCE

If in Part G.1 of this guidance you determine that the buffer requirements apply to your site, you 

have three compliance alternatives from which you can choose:

1. Provide and maintain a 50-foot buffer undisturbed natural buffer (Part 2.1.2.1a.i);

1 or

2. Provide and maintain an undisturbed natural buffer that is less than 50 feet and is 

supplemented by additional erosion and sediment controls, which in combination 

achieves the sediment load reduction equivalent to a 50-foot undisturbed natural buffer 

(Part 2.1.2.1a.ii);

1 or

3. If it is infeasible to provide and maintain an undisturbed natural buffer of any size, you 

must implement erosion and sediment controls that achieve the sediment load reduction 

equivalent to a 50-foot undisturbed natural buffer (Part 2.1.2.1a.iii).

1

The compliance alternative selected above must be maintained throughout the duration of 

permit coverage.

The following provides detailed guidance for how you can comply with each of the compliance 

alternatives. Part G.2.1 below provides guidance on how to provide and maintain natural 

buffers consistent with the alternatives 1 and 2, above. Part G.2.2 below provides guidance on 

how to comply with the requirement to provide a 50-foot buffer equivalent through erosion and 

sediment controls consistent with alternatives 2 and 3, above. 

G.2.1 Guidance for Providing and Maintaining Natural Buffers

The following guidance is intended to assist you in complying with the requirements to 

provide and maintain a natural buffer during construction. This part of the guidance 

applies to you if you choose either alternative 1 (50-foot buffer) or alternative 2 (a buffer 

of < 50 feet supplemented by additional erosion and sediment controls that achieve the 

equivalent sediment load reduction as the 50-foot buffer), or if you are providing a buffer 

in compliance with one of the small residential lot compliance alternatives in Part G.2.3 

below.

 

1 For the compliance alternatives in 1 and 2, you are not required to enhance the quality of the 

vegetation that already exists in the buffer, or provide vegetation if none exists (e.g., arid and semi-arid 

areas). You only need to retain and protect from disturbance the natural buffer that existed prior to the 

commencement of construction. Any preexisting structures or impervious surfaces are allowed in the 

natural buffer provided you retain and protect from disturbance the natural buffer area outside the 

preexisting disturbance. Similarly, for alternatives 2 and 3, you are required to implement and maintain 

sediment controls that achieve the sediment load reduction equivalent to the undisturbed natural buffer 

that existed on the site prior to the commencement of construction. In determining equivalent sediment 

load reductions, you may consider naturally non-vegetated areas and prior disturbances. See Part G.2.2 

of this Appendix for a discussion of how to determine equivalent reductions.
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G.2.1.1 Buffer Width Measurement

Where you are retaining a buffer of any size, the buffer should be measured

perpendicularly from any of the following points, whichever is further landward from the 

water:

1. The ordinary high water mark of the water body, defined as the line on the shore 

established by fluctuations of water and indicated by physical characteristics 

such as a clear, natural line impressed on the bank, shelving, changes in the 

character of soil, destruction of terrestrial vegetation, and/or the presence of litter 

and debris; or

2. The edge of the stream or river bank, bluff, or cliff, whichever is applicable.

Refer to Figure G – 2 and Figure G - 3. You may find that specifically measuring these 

points is challenging if the flow path of the surface water changes frequently, thereby 

causing the measurement line for the buffer to fluctuate continuously along the path of 

the waterbody. Where this is the case, EPA suggests that rather than measuring each 

change or deviation along the water’s edge, it may be easier to select regular intervals 

from which to conduct your measurement. For instance, you may elect to conduct your 

buffer measurement every 5 to 10 feet along the length of the water.

Additionally, note that if earth-disturbing activities will take place on both sides of a 

surface water that flows through your site, to the extent that you are establishing a buffer 

around this water, it must be established on both sides. For example, if you choose 

alternative 1 above, and your project calls for disturbances on both sides of a small 

stream, you would need to retain the full 50 feet of buffer on both sides of the water. 

However, if your construction activities will only occur on one side of the stream, you 

would only need to retain the 50-foot buffer on the side of the stream where the earthdisturbance will occur.
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Figure G - 2. This image shows buffer measurement from the ordinary high water mark of the 

water body, as indicated by a clear natural line impressed on the bank, shelving, changes in the 

character of the soil, destruction of terrestrial vegetation, and/or the presence of litter/debris.

Figure G - 3. This image shows buffer measurement from the edge of the bank, bluff, or cliff, 

whichever is applicable.
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G.2.1.2 Limits to Disturbance Within the Buffer

You are considered to be in compliance with this requirement if you retain and protect

from construction activities the natural buffer that existed prior to the commencement of 

construction. If the buffer area contains no vegetation prior to the commencement of 

construction (e.g., sand or rocky surface), you are not required to plant any additional 

vegetation. As noted above, any preexisting structures or impervious surfaces are 

allowed in the buffer provided you retain and protect from disturbance the vegetation in 

the buffer outside the preexisting disturbance.

To ensure that the water quality protection benefits of the buffer are retained during 

construction, you are prohibited from conducting any earth-disturbing activities within 

the buffer during permit coverage. In furtherance of this requirement, prior to 

commencing earth-disturbing activities on your site, you must delineate, and clearly 

mark off, with flags, tape, or a similar marking device, the buffer area on your site. The 

purpose of this requirement is to make the buffer area clearly visible to the people 

working on your site so that unintended disturbances are avoided.

While you are not required to enhance the quality of the vegetation that already exists 

within the buffer, you are encouraged to do so where such improvements will enhance 

the water quality protection benefits of the buffer. (Note that any disturbances within 

the buffer related to buffer enhancement are permitted and do not constitute 

construction disturbances.) For instance, you may want to consider targeted plantings 

where limited vegetation exists, or replacement of existing vegetation where invasive or 

noxious plant species (see http://plants.usda.gov/java/noxiousDriver) have taken over. 

In the case of invasive or noxious species, you may want to remove and replace them 

with a diversity of native trees, shrubs, and herbaceous plants that are well-adapted to 

the climatic, soil, and hydrologic conditions on the site. You are also encouraged to limit 

the removal of naturally deposited leaf litter, woody debris, and other biomass, as this 

material contributes to the ability of the buffer to retain water and filter pollutants.

If a portion of the buffer area adjacent to the surface water is owned by another party 

and is not under your control, you are only required to retain and protect from 

construction activities the portion of the buffer area that is under your control. For 

example, if you elect alternative 1 above (provide and maintain a 50-foot buffer), but 10 

feet of land immediately adjacent to the surface water is owned by a different party 

than the land on which your construction activities are taking place and you do not 

have control over that land, you must only retain and protect from construction activities 

the 40-foot buffer area that occurs on the property on which your construction activities 

are taking place. EPA would consider you to be in compliance with this requirement 

regardless of the activities that are taking place in the 10-foot area that is owned by a 

different party than the land on which your construction activities are taking place that 

you have no control over. 

G.2.1.3 Discharges to the Buffer

You must ensure that all discharges from the area of earth disturbance to the natural 

buffer are first treated by the site’s erosion and sediment controls (for example, you must 

comply with the Part 2.1.2.2 requirement to establish sediment controls around the 

downslope perimeter of your site disturbances), and if necessary to prevent erosion 

caused by stormwater flows within the buffer, you must use velocity dissipation devices. 

The purpose of this requirement is to decrease the rate of stormwater flow and 

encourage infiltration so that the pollutant filtering functions of the buffer will be 
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achieved. To comply with this requirement, construction operators typically will use 

devices that physically dissipate stormwater flows so that the discharge entering the 

buffer is spread out and slowed down. 

G.2.1.4 SWPPP Documentation

You are required to document in your SWPPP the natural buffer width that is retained. 

For example, if you are complying with alternative 1, you must specify in your SWPPP that 

you are providing a 50-foot buffer. Or, if you will be complying with alternative 2, you 

must document the reduced width of the buffer you will be retaining (and you must also 

comply with the requirements in Part 2.1.2.1c to describe the erosion and sediment 

controls you will use to achieve an equivalent sediment reduction, as described in Part 

G.2.2 below). Note that you must also show any buffers on your site plan in your SWPPP 

consistent with Part 7.2.6.3. Additionally, if any disturbances related to the exceptions in 

Part 2.1.2.1e occur within the buffer area, you must document this in the SWPPP. 

G.2.2 Guidance for Providing the Equivalent Sediment Reduction as the 50-foot Buffer 

If you are selecting Alternative 2 (provide and maintain a buffer that is less than 50 feet 

that is supplemented by additional erosion and sediment controls that, together, 

achieve the equivalent sediment load reduction as the 50-foot buffer) or Alternative 3

(implement erosion and sediment controls that achieve the equivalent sediment load 

reduction as the 50-foot buffer), the following guidance is intended to assist you in 

demonstrating that you will achieve the equivalent sediment reduction as the 50-foot 

buffer.

G.2.2.1 Determine Whether it is Feasible to Provide a Reduced Buffer

EPA recognizes that there will be a number of situations in which it will be infeasible to 

provide and maintain a buffer of any width. While some of these situations may exempt 

you from the buffer requirement entirely (see G.1.2), if you do not qualify for one of these

exemptions, there still may be conditions or circumstances at your site that make it 

infeasible to provide a natural buffer. For example, there may be sites where a 

significant portion of the property on which the earth-disturbing activities will occur is 

located within the buffer area, thereby precluding the retention of natural buffer areas. 

EPA believes there are likely to be other examples of situations that make it infeasible to 

provide any buffer area.

Therefore, in choosing between the 2 different compliance alternatives (Alternative 2 or 

3), you should only elect to comply with Alternative 2 if it is feasible for you to retain any 

natural buffer on your site. (Note: For any buffer width retained, you are required to 

comply with the requirements in Part G.2.1, above, concerning the retention of 

vegetation and restricting earth disturbances.) Similarly, if you determine that it is 

infeasible to provide a natural buffer of any size during construction, you should elect to 

comply with Alternative 3. After making this determination, you should proceed to Part 

G.2.2.2 to determine how to provide controls that, together with any buffer areas that is 

being retained, if applicable, will achieve an equivalent sediment load reduction as the 

50-foot buffer.

G.2.2.2 Design Controls That Provide Equivalent Sediment Reduction as 50-foot Buffer

You must next determine what additional controls must be implemented on your site 

that, alone or in combination with any retained natural buffer, achieve a reduction in 

sediment equivalent to that achieved by a 50-foot buffer. 
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Note that if only a portion of the natural buffer is less than 50 feet, you are only required 

to implement erosion and sediment controls that achieve the sediment load reduction 

equivalent to the 50-foot buffer for discharges through that area. You would not be 

required to provide treatment of stormwater discharges that flow through 50 feet or more 

of natural buffer. See Figure G - 4.

Figure G - 4 Example of how to comply with the requirement to provide the equivalent sediment 

reduction when only a portion of your earth-disturbances discharge to a buffer of less than 50-

feet.

To comply with this requirement, you are required to do the following:

Step1 - Estimate the sediment reduction expected from your site if you had retained a 

50-foot natural buffer;

Step 2 - Design controls that alone or in combination with any width of buffer retained 

achieve the equivalent sediment removal efficiency as that expected from the 50-foot 

buffer; and

Step 3 - Document in your SWPPP how your controls will achieve the equivalent sediment 

removal efficiency of the 50-foot buffer.

Guidelines to help you work through these requirements are provided below.
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a. Step 1 - Estimate the Sediment Reduction from the 50-foot Buffer 

In order to design controls that match the sediment removal efficiency of a 50-

foot buffer, you first need to know what this efficiency is for your site. The 

sediment removal efficiencies of natural buffers vary according to a number of 

site-specific factors, including precipitation, soil type, land cover, slope length, 

width, steepness, and the types of sediment controls used to reduce the 

discharge of sediment prior to the buffer. EPA has simplified this calculation by 

developing buffer performance tables covering a range of vegetation and soil 

types for the areas covered by the CGP. See Attachment 1, Tables G - 8 through

G - 15. Note: buffer performance values in Tables G - 8 through G - 15 represent 

the percent of sediment captured through the use of perimeter controls (e.g., silt 

fences) and 50-foot buffers at disturbed sites of fixed proportions and slopes.2 

Using Tables G - 8 through G - 15 (see Attachment 1), you can determine the 

sediment removal efficiency of a 50-foot buffer for your geographic area by 

matching the vegetative cover type that best describes your buffer area and the 

type of soils that predominate at your site. For example, if your site is located in 

Massachusetts (Table G - 9), and your buffer vegetation corresponds most closely 

with that of tall fescue grass, and the soil type at your site is best typified as sand, 

your site’s sediment removal efficiency would be 81 percent. 

In this step, you should choose the vegetation type in the tables that most closely 

matches the vegetation that would exist naturally in the buffer area on your site 

regardless of the condition of the buffer. However, because you are not required 

to plant any additional vegetation in the buffer area, in determining what 

controls are necessary to meet this sediment removal equivalency in Step 2 

below, you will be able to take credit for this area as a fully vegetated “natural 

buffer.”

Similarly, if a portion of the buffer area adjacent to the surface water is owned by 

another party and is not under your control, you can treat the area of land not 

under control as having the equivalent vegetative cover and soil type that 

 

2 EPA used the following when developing the buffer performance tables:

 The sediment removal efficiencies are based on the U.S. Department of Agriculture’s RUSLE2 (“Revised Universal 

Soil Loss Equation 2”) model for slope profiles using a 100-foot long denuded slopes.

 Sediment removal was defined as the annual sediment delivered at the downstream end of the 50-foot natural 

buffer (tons/yr/acre) divided by the annual yield from denuded area (tons/yr/acre).

 As perimeter controls are also required by the CGP, sediment removal is in part a function of the reduction due 

to a perimeter control (i.e., silt fence) located between the disturbed portion of the site and the upstream 

edge of the natural buffer and flow traveling through a 50-foot buffer of undisturbed natural vegetation.

 It was assumed that construction sites have a relatively uniform slope without topographic features that 

accelerate the concentration for erosive flows.

 It was assumed that vegetation has been removed from the disturbed portion of the site and a combination of 

cuts and fills have resulted in a smooth soil surface with limited retention of near-surface root mass

To represent the influence of soil, EPA analyzed 11 general soil texture classifications in its evaluation of buffer 

performance. To represent different types of buffer vegetation, EPA evaluated 4 or more common vegetative types for 

each state/territory covered under the permit. For each vegetation type evaluated, EPA considered only permanent, 

non-grazed and non-harvested vegetation, on the assumption that a natural buffer adjacent to the surface water will 

typically be undisturbed. EPA also evaluated slope steepness and found that sediment removal efficiencies present in 

Tables G -8 through G - 15 are achievable for slopes that are less than nine percent.
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predominates on the portion of the property on which your construction activities 

are occurring. 

For example, if your earth-disturbances occur within 50 feet of a surface 

water, but the 10 feet of land immediately adjacent to the surface water 

is owned by a different party than the land on which your construction 

activities are taking place and you do not have control over that land, 

you can treat the 10 foot area adjacent to the stream as having the 

equivalent soil and vegetation type as predominates in the 40 foot area 

under your control. You would then make the same assumption in Step 2 

for purposes of determining the equivalent sediment removal.

Alternatively, you may do your own calculation of the effectiveness of the 50-foot 

buffer based upon your site-specific conditions, and may use this number as your 

sediment removal equivalency standard to meet instead of using Tables G - 8 

through G - 15. This calculation must be documented in your SWPPP.

b. Step 2 - Design Controls That Match the Sediment Removal Efficiency of the 50-

foot Buffer

Once you have determined the estimated sediment removal efficiency of a 50-

foot buffer for your site in Step 1, you will be required to select stormwater controls 

that will provide an equivalent sediment load reductions. These controls can 

include the installation of a single designed control, such as a sediment pond, 

additional perimeter controls, or other type of device. Alternatively, you may 

elect to install a combination of stormwater controls and to retain some amount 

of a buffer. Whichever control(s) you select, you must demonstrate in your SWPPP 

that the controls will provide at a minimum the same sediment removal 

capabilities as the 50-foot buffer (Step 1). You are allowed to take credit for the 

removal efficiencies of your required perimeter controls in your calculation of 

equivalency, because these were included in calculating the buffer removal 

efficiencies in tables G - 8 through G - 15. (Note: You are reminded that the 

controls must be kept in effective operating condition until you have completed 

final stabilization on the disturbed portions of the site discharging to the surface 

water.)

To make the determination that your controls and/or buffer area achieve an 

equivalent sediment load reduction as the 50-foot buffer, you will need to use a 

model or other type of calculator. As mentioned above, there are a variety of 

models available that can be used to support your calculation, including USDA’s 

RUSLE-series programs and the WEPP erosion model, SEDCAD, SEDIMOT, or other 

models. A couple of examples are provided in Attachment 3 to help illustrate 

how this determination could be made.

If you are retaining a buffer of less than 50 feet, you may take credit for the 

removal that will occur from the reduced buffer and only need to provide 

additional controls to make up the difference between the removal efficiency of 

a 50 foot buffer and the removal efficiency of the narrower buffer. For example, 

if you are retaining a 30 foot buffer, you can account for the sediment removal 

provided by the 30-foot buffer retained, and you will only need to design controls 

to make up for the additional removal provided by the 20-foot of buffer that is 

not being provided. To do this, you would plug the width of the buffer that is 
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retained into RUSLE or another model, along with other stormwater controls that 

will together achieve a sediment reduction equivalent to a natural 50-foot buffer.

As described in Step 1 above, you can take credit for the area you have retained 

as a “natural buffer” as being fully vegetated, regardless of the condition of the 

buffer area. 

For example, if your earth-disturbances occur 30 feet from a surface 

water, but the 10 feet of land immediately adjacent to the surface water 

is owned by a different party than the land on which your construction 

activities are taking place and you do not have control over that land, 

you can treat the 10-foot area as a natural buffer, regardless of the 

activities that are taking place in the area. Therefore, you can assume (for 

purposes of your equivalency calculation) that your site is providing the 

sediment removal equivalent of a 30-foot buffer, and you will only need to 

design controls to make up for the additional removal provided by the 20-

foot of buffer that is not being provided.

c. Step 3 - Document How Site-Specific Controls Will Achieve the Sediment Removal

Efficiency of the 50-foot Buffer 

In Steps 1 and 2, you determined both the expected sediment removal efficiency 

of a 50-foot buffer at your site, and you used this number as a performance 

standard to design controls to be installed at your site, which alone or in 

combination with any retained natural buffer, achieves the expected sediment 

removal efficiency of a 50-foot buffer at your site. The final step is to document in 

your SWPPP the information you relied on to calculate the equivalent sediment 

reduction as an undisturbed natural buffer.

EPA will consider your documentation to be sufficient if it generally meets the 

following:

– For Step 1, refer to the table in Attachment 1 that you used to derive your 

estimated 50-foot buffer sediment removal efficiency performance. Include 

information about the buffer vegetation and soil type that predominate at 

your site, which you used to select the sediment load reduction value in 

Tables G - 8 through G - 15. Or, if you conducted a site-specific calculation

for sediment removal efficiency, provide the specific removal efficiency, and 

the information you relied on to make your site-specific calculation. 

– For Step 2: (1) Specify the model you used to estimate sediment load 

reductions from your site; and (2) the results of calculations showing how your 

controls will meet or exceed the sediment removal efficiency from Step 1.

If you choose Alternative 3, you must also include in your SWPPP a description of 

why it is infeasible for you to provide and maintain an undisturbed natural buffer 

of any size.

G.2.3 Small Residential Lot Compliance Alternatives

In this part of Appendix G, EPA

provides additional compliance 

alternatives for operators of small 

residential lots. In accordance 

with Part 2.1.2.1e.iv, operators of 

A small residential lot is a lot or grouping of lots 

being developed for residential purposes that will 

disturb less than 1 acre of land, but that is part of a 

larger residential project that will ultimately disturb 

greater than or equal to 1 acre. 
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small residential lots who do not provide a 50-foot buffer are not required to make the 

demonstration outlined in Part G.2.2.2. Instead, qualifying operators can comply with the 

buffer requirement by choosing to implement a set of traditional sediment and erosion 

controls from the menu of practices provided in Part G.2.3.2. 

EPA has developed two different alternatives for compliance. The following steps 

describe how a small residential lot operator would achieve compliance with these 2 

alternatives. 

G.2.3.1 Step 1 – Determine if You are Eligible for the Small Residential Lot Compliance 

Alternatives

In order to be eligible for the small residential lot compliance alternatives, the following 

conditions must be met:

a. The lot or grouping of lots meets the definition of “small residential lot”; and 

b. The operator must comply with all other requirements in Part 2.1.2.1, including:

i. Ensure that all discharges from the area of earth disturbance to the natural buffer 

are first treated by the site’s erosion and sediment controls, and use velocity 

dissipation devices if necessary to prevent erosion caused by stormwater within 

the buffer; 

ii. Document in the SWPPP the natural buffer width retained on the property, and 

show the buffer boundary on your site plan; and

iii. Delineate, and clearly mark off, with flags, tape, or other similar marking device,

all natural buffer areas.

G.2.3.2 Step 2 – Implement the Requirements of the Small Residential Lot Compliance Alternative 

Selected

You must next choose from one of two small residential lot compliance alternatives and 

implement the stormwater control practices associated with that alternative. 

Note: The compliance alternatives provided below are not mandatory. Operators of 

small residential lots can alternatively choose to comply with the any of the options 

that are available to other sites in Part 2.1.2.1a, described in Parts G.2.1 and G.2.2 in 

this appendix.

a. Small Residential Lot Compliance Alternative 1 

Alternative 1 is a straightforward tiered- technology approach that specifies the 

controls that a small residential lot must implement based on the buffer width 

retained. To achieve compliance with Alternative 1, you must implement the 

controls specified in Table G – 1 based on the buffer width to be retained. See

footnote 3, below, for a description of the controls you must implement.

For example, if you are an operator of a small residential lot that will be 

retaining a 35-foot buffer and you choose Small Residential Lot 

Compliance Alternative 1, you must implement double perimeter controls 

between earth disturbances and the surface water. 

In addition to implementing the applicable control, you must also document in 

your SWPPP how you will comply with Alternative 1.
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Table G - 1. Alternative 1 Requirements3 

Retain 50-foot Buffer Retain <50 and >30 foot 

Buffer

Retain ≤ 30 foot Buffer

No Additional 

Requirements

Double Perimeter 

Controls

Double Perimeter 

Controls and 7-Day Site 

Stabilization

b. Small Residential Lot Compliance Alternative 2

Alternative 2 specifies the controls that a builder of a small lot must implement 

based on both the buffer width retained and their risk of sediment discharge. By 

incorporating the sediment risk, this approach may result in the implementation of 

controls that are more appropriate for the site’s specific conditions. 

Step 1 – Determine Your Site’s Sediment Risk Level

To meet the requirements of Alternative 2, you must first determine your site’s 

sediment discharge “risk level” based on the site’s slope, location, and soil type. 

To help you to determine your site’s sediment risk level, EPA has developed five 

different tables for different slope conditions. You must select the table that most 

closely corresponds to your site’s average slope. 

For example, if your site’s average slope is 7 percent, you would use Table 

G – 4 to determine your site’s sediment risk. 

After you determine which table applies to your site, you must then use the table 

to determine the “risk level” (e.g., “low”, “moderate”, or “high”) that corresponds 

to your site’s location and predominant soil type.

4

 

3 Description of Additional Controls Applicable to Small Residential Lot Compliance 

Alternatives 1 and 2:

 No Additional Requirements: If you implement a buffer of 50 feet or greater, then you 

are not subject to any additional requirements. Note that you are required to install 

perimeter controls between the disturbed portions of your site and the buffer in 

accordance with Part 2.1.2.2.

 Double Perimeter Control: In addition to the reduced buffer width retained on your 

site, you must provide a double row of perimeter controls between the disturbed 

portion of your site and the surface water spaced a minimum of 5 feet apart. 

 Double Perimeter Control and 7-Day Site Stabilization: In addition to the reduced 

buffer width retained on your site and the perimeter control implemented in 

accordance with Part 2.1.2.2, you must provide a double row of perimeter controls 

between the disturbed portion of your site and the surface water spaced a minimum 

of 5 feet apart, and you are required to complete the stabilization activities specified 

in Parts 2.2.1.2a and/or 2.2.1.2b within 7 calendar days of the temporary or 

permanent cessation of earth-disturbing activities.

4 One source for determining your site’s predominant soil type is the USDA’s Web Soil Survey 

located at http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx. 
February 15, 2012

G -15 of 24

For example, based on Table G - 3, a site located in New Hampshire with 

a 4 percent average slope and with predominately sandy clay loam soils 

would fall into the “moderate” risk level. 

Table G - 2. Risk Levels for Sites with Average Slopes of ≤ 3 Percent

 Soil Type

Location Clay

Silty Clay Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, Loamy 

Sand or Silty 

Clay

Loam, Silt, 

Sandy Loam or 

Silt Loam

Guam Moderate Moderate Moderate Moderate High

Puerto Rico Moderate Moderate Moderate Moderate High

Virgin Islands Low Moderate Low Moderate Moderate

American Samoa Moderate Moderate Moderate Moderate High

Massachusetts and New 

Hampshire Low Moderate Low Low Moderate

Idaho Low Low Low Low Low

New Mexico Low Low Low Low Low

Washington D.C. Low Moderate Low Low Moderate

Table G - 3. Risk Levels for Sites with Average Slopes of > 3 Percent and ≤ 6 Percent

 Soil Type

Location Clay

Silty Clay Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, Loamy 

Sand or Silty 

Clay

Loam, Silt, 

Sandy Loam or 

Silt Loam

Guam Moderate Moderate Moderate Moderate High

Puerto Rico Moderate Moderate Moderate Moderate High

Virgin Islands Moderate Moderate Moderate Moderate High

American Samoa High High Moderate High High

Massachusetts and New 

Hampshire Moderate Moderate Low Moderate High

Idaho Low Low Low Low Low

New Mexico Low Low Low Low Moderate

Washington D.C. Moderate Moderate Moderate Moderate High

Table G - 4. Risk Levels for Sites with Average Slopes of > 6 Percent and ≤ 9 Percent

 Soil Type

Location Clay

Silty Clay Loam 

or Clay-Loam Sand

Sandy Clay 

Loam, Loamy 

Sand or Silty 

Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Guam Moderate High Moderate High High

Puerto Rico Moderate High Moderate Moderate High
February 15, 2012

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Virgin Islands Moderate Moderate Moderate Moderate High

American Samoa High High High High High

Massachusetts and New 

Hampshire Moderate Moderate Moderate Moderate High

Idaho Low Low Low Low Low

New Mexico Low Low Low Low Moderate

Washington D.C. Moderate Moderate Moderate Moderate High

Table G - 5. Risk Levels for Sites with Average Slopes of > 9 Percent and ≤ 15 Percent

 Soil Type

Location Clay

Silty Clay 

Loam or ClayLoam Sand

Sandy Clay 

Loam, Loamy 

Sand or Silty 

Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Guam High High High High High

Puerto Rico High High High High High

Virgin Islands Moderate High Moderate High High

American Samoa High High High High High

Massachusetts and New 

Hampshire Moderate Moderate Moderate Moderate High

Idaho Low Low Low Low Low

New Mexico Low Moderate Low Moderate Moderate

Washington D.C. Moderate High Moderate Moderate High

Table G - 6. Risk Levels for Sites with Average Slopes of > 15 Percent

 Soil Type

Location Clay

Silty Clay 

Loam or ClayLoam Sand

Sandy Clay 

Loam, Loamy 

Sand or Silty 

Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Guam High High High High High

Puerto Rico High High High High High

Virgin Islands High High High High High

American Samoa High High High High High

Massachusetts and New 

Hampshire High High Moderate High High

Idaho Low Low Low Low Moderate

New Mexico Moderate Moderate Moderate Moderate High

Washington D.C. High High Moderate High High

Step 2 – Determine Which Additional Controls Apply
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Once you determine your site’s “risk level”, you must next determine the 

additional controls you need to implement on your site, based on the width of 

buffer you plan to retain. Table G - 7 specifies the requirements that apply based 

on the “risk level” and buffer width retained. See footnote 3, above, for a 

description of the additional controls that are required.

For example, if you are the operator of a small residential lot that falls into 

the “moderate” risk level, and you decide to retain a 20-foot buffer, using 

Table G-7 you would determine that you need to implement double 

perimeter controls to achieve compliance with Part 2.1.2.1.

You must also document in your SWPPP your compliance with Alternative 2.

Table G - 7. Alternative 2 Requirements2

Risk Level Based 

on Estimated Soil 

Erosion

Retain ≥ 50’ 

Buffer

Retain <50’ and 

>30’ Buffer

Retain ≤30’ and 

>10’ Buffer

Retain ≤ 10’ 

Buffer

Low Risk No Additional 

Requirements 

No Additional 

Requirements

Double Perimeter 

Control

Double Perimeter 

Control

Moderate Risk No Additional 

Requirements

Double Perimeter 

Control

Double Perimeter 

Control

Double Perimeter 

Control and 7-

Day Site 

Stabilization

High Risk No Additional 

Requirements

Double Perimeter 

Control

Double Perimeter 

Control and 7-

Day Site 

Stabilization

Double Perimeter 

Control and 7-

Day Site 

Stabilization 
February 15, 2012

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-

ATTACHMENT 1

Sediment Removal Efficiency Tables5

EPA recognizes that very high removal efficiencies, even where theoretically achievable by a 

50-foot buffer, may be very difficult to achieve in practice using alternative controls. Therefore 

in the tables below, EPA has limited the removal efficiencies to a maximum of 90%. Efficiencies 

that were calculated at greater than 90% are shown as 90%, and this is the minimum percent 

removal that must be achieved by alternative controls.

Table G - 8. Estimated 50-foot Buffer Performance in Idaho*

Estimated % Sediment Removal

Type of Buffer Vegetation** Clay

Silty Clay 

Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, 

Loamy Sand 

or Silty Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Tall Fescue Grass 42 52 44 48 85

Medium-density Weeds 28 30 28 26 60

Low-density Warm-season 

Native Bunchgrass (i.e., 

Grama Grass)

25 26 24 24 55

Northern Mixed Prairie Grass 28 30 28 26 50

Northern Range Cold Desert 

Shrubs 28 28 24 26 50

* Applicable for sites with less than nine percent slope

** Characterization focuses on the under-story vegetation

Table G - 9. Estimated 50-foot Buffer Performance in Massachusetts and New Hampshire*

Estimated % Sediment Removal

Type of Buffer Vegetation** Clay

Silty Clay 

Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, 

Loamy Sand 

or Silty Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Warm-season Grass (i.e., 

Switchgrass, Lemongrass) 79 90 90 90 90

Cool-season Dense Grass 

(Kentucky Bluegrass, Smooth 

Bromegrass, Timothy)

78 90 90 90 90

Tall Fescue Grass 76 90 81 89 90

Medium-density Weeds 66 76 60 72 66

* Applicable for sites with less than nine percent slope

** Characterization focuses on the under-story vegetation

 

5 The buffer performances were calculated based on a denuded slope upgradient of a 50-foot 

buffer and a perimeter controls, as perimeter controls are a standard requirement (see Part 

2.1.2.2). 
February 15, 2012

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Table G - 10. Estimated 50-foot Buffer Performance in New Mexico*

 

Estimated % Sediment Removal

Type of Buffer Vegetation ** Clay

Silty Clay 

Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, 

Loamy Sand 

or Silty Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Tall Fescue grass 71 85 80 86 90

Medium-density Weeds 56 73 55 66 78

Low-density Warm-season 

Native Bunchgrass (i.e., 

Grama Grass)

53 70 51 62 67

Southern Mixed Prairie Grass 53 71 52 63 50

Southern Range Cold Desert 

Shrubs 56 73 55 65 53

* Applicable for sites with less than nine percent slope

** Characterization focuses on the under-story vegetation

Table G - 11. Estimated 50-foot Buffer Performance in Washington, DC*

 

Estimated % Sediment Removal

Type of Buffer Vegetation ** Clay

Silty Clay 

Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, 

Loamy Sand 

or Silty Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Warm-season Grass (i.e., 

Switchgrass, Lemongrass) 82 90 90 90 90

Cool-season Dense Grass 

(Kentucky Bluegrass, Smooth 

Bromegrass, Timothy)

81 90 90 90 90

Tall Fescue Grass 79 90 83 89 90

Medium-density Weeds 71 79 66 75 74

* Applicable for sites with less than nine percent slope

** Characterization focuses on the under-story vegetation

Table G - 12. Estimated 50-foot Buffer Performance in American Samoa*

 

Estimated % Sediment Removal

Type of Buffer Vegetation ** Clay

Silty Clay 

Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, 

Loamy Sand 

or Silty Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Bahiagrass (Permanent cover) 82 90 90 90 83

Warm-season Grass (i.e., 

Switchgrass, Lemongrass) 82 90 90 90 85

Dense Grass 82 90 90 90 83

Tall Fescue Grass 82 89 82 89 79

Medium-density Weeds 70 73 62 75 59

* Applicable for sites with less than nine percent slope

** Characterization focuses on the under-story vegetation
February 15, 2012

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Table G - 13. Estimated 50-foot Buffer Performance in Guam*

 

Estimated % Sediment Removal

Type of Buffer Vegetation ** Clay

Silty Clay 

Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, 

Loamy Sand 

or Silty Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Bahiagrass (Permanent 

cover) 80 90 90 90 89

Warm-season Grass (i.e., 

Switchgrass, Lemongrass) 80 90 90 90 90

Dense Grass 79 90 90 90 89

Tall Fescue Grass 76 90 80 88 87

Medium-density Weeds 63 73 53 68 61

* Applicable for sites with less than nine percent slope

** Characterization focuses on the under-story vegetation

Table G - 14. Estimated 50-foot Buffer Performance in Puerto Rico*

 

Estimated % Sediment Removal

Type of Buffer Vegetation** Clay

Silty Clay 

Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, 

Loamy Sand 

or Silty Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Bahiagrass (Permanent 

cover) 83 90 90 90 90

Warm-season Grass (i.e., 

Switchgrass, Lemongrass) 83 90 90 90 90

Dense Grass 83 90 90 90 90

Tall Fescue Grass 82 90 84 90 89

Medium-density Weeds 72 78 65 76 64

* Applicable for sites with less than nine percent slope

** Characterization focuses on the under-story vegetation

Table G - 15. Estimated 50-foot Buffer Performance in Virgin Islands*

 

Type of Buffer Vegetation** Clay

Silty Clay 

Loam or 

Clay-Loam Sand

Sandy Clay 

Loam, 

Loamy Sand 

or Silty Clay

Loam, Silt, 

Sandy Loam 

or Silt Loam

Bahiagrass (Permanent 

cover) 85 90 90 90 90

Warm-season Grass (i.e., 

Switchgrass, Lemongrass) 86 90 90 90 90

Dense Grass 85 90 90 90 90

Tall Fescue Grass 85 90 88 90 89

Medium-density Weeds 75 77 71 78 63

* Applicable for sites with less than nine percent slope

** Characterization focuses on the under-story vegetation

ATTACHMENT 2

Using the Sediment Removal Efficiency Tables – Questions and Answers
February 15, 2012

G -21 of 24

– What if my specific buffer vegetation is not represented in Tables G - 8 through G - 15? 

Tables G - 8 through G - 15 provide a wide range of factors affecting buffer performance; 

however, there may be instances where the specific buffer vegetation type on your site is 

not listed. If you do not see a description of the type of vegetation present at your site, you 

should choose the vegetation type that most closely matches the vegetation type on your 

site. You can contact your local Cooperative Extension Service Office 

(www.csrees.usda.gov/Extension) for assistance in determining the vegetation type in Tables 

G - 8 through G - 15 that most closely matches your site-specific vegetation. 

– What if there is high variability in local soils? EPA recognizes that there may be a number of 

different soil type(s) on any given construction site. General soil information can be 

obtained from USDA soil survey reports (http://websoilsurvey.nrcs.usda.gov) or from individual 

site assessments performed by a certified soil expert. Tables G - 8 through G - 15 present 

eleven generic soil texture classes, grouping individual textures where EPA has determined 

that performance is similar. If your site contains different soil texture classes, you should use 

the soil type that best approximates the predominant soil type at your site.

– What if my site slope is greater than 9 percent after final grade is reached? As indicated in 

the buffer performance tables, the estimated sediment removal efficiencies are associated 

with disturbed slopes of up to 9 percent grade. Where your graded site has an average 

slope of greater than 9 percent, you should calculate a site-specific buffer performance.

– How do I calculate my own estimates for sediment reduction at my specific site? If you 

determine that it is necessary to calculate your own sediment removal efficiency using sitespecific conditions (e.g., slopes at your site are greater than 9 percent), you can do so by 

choosing from a range of available mathematical models that are available to facilitate this 

calculation, including USDA’s RUSLE-series programs and the WEPP erosion model, SEDCAD, 

SEDIMOT, or other equivalent models. 

– What is my estimated buffer performance if my site location is not represented by Tables G -

8 through G - 15? If your site is located in an area not represented by Tables G - 8 through G 

- 15, you should use the table that most closely approximates conditions at your site. You 

may also choose to conduct a site-specific calculation of the buffer performance.

– What if only a portion of my site drains to the buffer area? If only a portion of your site drains 

to a surface water, where that water is within 50 feet of your construction activities, you are 

only required to meet the equivalency requirement for the stormwater flows corresponding 

to those portions of the site. See Example 2 below for an example of how this is expected to 

work.
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ATTACHMENT 3

Examples of How to Use the Sediment Removal Efficiency Tables

Example 1. Comparatively Wet Location (7.5 acre site located in Massachusetts)

The operator of a 7.5-acre construction site in Massachusetts has determined that it is infeasible 

to establish a buffer of any size on their site, and is now required to select and install controls that 

will achieve an equivalent sediment load reduction as that estimated in G - 9 for their site 

conditions. The first step is to identify what percentage of eroded sediment is estimated to be 

retained from a 50-foot buffer. For this example, it is assumed that the site has a relatively 

uniform gentle slope (3 percent), so Table G - 9 can be used to estimate the 50-foot buffer 

sediment load reduction. If the site’s buffer vegetation is best typified by cool-season dense 

grass and the underlying soil is of a type best described as loamy sand, the 50-foot buffer is 

projected to capture 90 percent of eroded sediment from the construction site.

The second step is to determine what sediment controls can be selected and installed in 

combination with the perimeter controls already required to be implemented at the site (see 

Part 2.1.2.2), which will achieve the 90 percent sediment removal efficiency from Table G - 9. For 

this example, using the RUSLE2 profile model, it was determined that installing a pair of shallowsloped diversion ditches to convey runoff to a well-designed and maintained sediment basin 

provides 99 percent sediment removal. Because the estimated sediment reduction is greater 

than the required 90 percent that a 50-foot buffer provides, the operator will have met the 

buffer requirements. See Figure G - 5. The operator could also choose a different set of controls, 

as long as they achieve at least a 90 percent sediment removal efficiency.
February 15, 2012

G -23 of 24

Figure G - 5. Example 1 – Equivalent Sediment Load Reductions at a 7.5 ac Site in MA.

Example 2. Arid Location With Pre-existing Disturbances in the Natural Buffer (6.5 acre site 

located in New Mexico)

An operator of a site in New Mexico determines that it is not practicable to provide a 50-foot 

buffer, but a 28-foot buffer can be provided. Because the operator will provide a buffer that is 

less than 50 feet, the operator must determine which controls, in combination with the 28-foot 

buffer, achieve a sediment load reduction equivalent to the 50-foot buffer. In this example, the 

project will disturb 6.5 acres of land, but only 1.5 acres of the total disturbed area drains to the 

buffer area. Within the 28-foot buffer area is a preexisting concrete walkway. Similar to Example 

1, the equivalence analysis starts with Step 1 (Part G.2.2.2) with a review of the New Mexico 

buffer performance (Table G - 10). The operator determines that the predominate vegetation 

type in the buffer area is prairie grass and the soil type is similar to silt, and that the site is of a 

uniform, shallow slope (e.g., 3 percent grade). Although the operator will take credit for the 

disturbance caused by the concrete walkway as a natural buffer in Step 2, here the operator 

can treat the entire buffer area as being naturally vegetated with prairie grass. Based on this 

information, the operator refers to Table G - 10 to estimate that the 50-foot buffer would retain 50

percent of eroded soil.
February 15, 2012

G -24 of 24

The second step is to determine, based on the 50 percent sediment removal efficiency found in 

Table G - 10, what sediment controls in combination with the 28-foot buffer area, can be 

implemented to reduce sediment loads by 50 percent or more. The operator does not have to 

account the reduction in buffer function caused by the preexisting walkway, and can take 

credit for the entire 28-foot buffer being fully vegetated in the analysis. For this example, using 

the RUSLE2 profile model, the operator determined that installing a fiber roll barrier between the 

silt fence (already required by Part 2.1.2.2) and the 28-foot buffer will achieve an estimated 84 

percent sediment removal efficiency. See Figure G - 6. Note that this operator is subject to the 

requirement in Part 2.1.2.1b.i to ensure that discharges through the silt fence, fiber roll barrier, 

and 28-foot buffer do not cause erosion within the buffer. The estimated sediment reduction is 

greater than the required 50 percent; therefore the operator will have met the buffer alternative 

requirement.

Figure G - 6. Example 2 – Equivalent Sediment Load Reductions at a 6.5 ac Site in NM.