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Excluded Riparian Buffer Practices for Cattle Pasture Point System BMPs
Tar-Pamlico Agriculture Rule

Background:
Each of the excluded pasture riparian buffer practices below meets the definition of a best management practice for pasture-based production or management of cattle established in S.L. 2001-355 Section 4(c). For additional information see Environmental Management Commission rule 15A NCAC 2B .0256.

Definitions:
An excluded riparian buffer is adjacent to intermittent or perennial streams in one or more pasture units in combination with a physical barrier that excludes cattle access to both the buffer and the stream(s) within the unit(s). A stream shall be defined as a natural, modified natural or manmade intermittent or perennial stream and does not include an ephemeral stream. The definition of stream includes ditches, channels and conveyances. Intermittent stream or ditch means a well-defined channel that contains water for only part of the year, typically during winter and spring when the aquatic bed is below the water table. The flow may be heavily supplemented by storm water runoff. An intermittent stream often lacks the biological and hydrological characteristics commonly associated with the conveyance of water. Perennial stream or ditch means a well-defined channel that contains water year around during a year of normal rainfall. Groundwater is the primary source of water for a perennial stream, but it also carries storm water runoff. A perennial stream exhibits the typical biological, hydrological, physical characteristics commonly associated with the conveyance of water. Ephemeral (stormwater) stream or ditch means a feature that carries only stormwater in direct response to precipitation with water flowing only during and shortly after large precipitation events. An ephemeral stream may or may not have a well-defined channel, the aquatic bed is always above the water table and stormwater runoff is a primary source of water. An ephemeral stream typically lacks the biological, hydrological, and physical characteristics commonly associated with the continuous or intermittent conveyance of water. Any of several buffer practice options described below may be used. The practice shall reliably eliminate direct deposition of cattle manure into such waters and reduce indirect nutrient transport from pastures into such waters.

Performance Objectives:
This excluded buffer BMP shall result in establishment or conservation of a stable, well-vegetated, riparian buffer with buffer and stream free from cattle access. This excluded buffer BMP can be expected to shift waste deposition out of the stream and buffer and provide for reduction in nitrogen content of flows from grazed pastures before they reach the stream.

General Considerations:
All riparian buffer practices identified below shall meet the following basic specifications:

To reliably exclude cattle and maintain buffer integrity, the producer is to consider the following factors:

Individual Riparian Buffer Practices: Options for Pasture
The following buffer practices originated from work to create the Nutrient Loss Evaluation Worksheet which provided buffer widths and associated nitrogen loss efficiencies. The Soil and Water Conservaton Commission approved these riparian buffer practices as standard BMPs for cropland in accordance with 15A NCAC 2B .0256. Excluded Filter Strip A filter strip must follow the USDA – Natural Resources Conservation Service Field Office Technical Guide for North Carolina (FOTG) no. 393, Filter Strip (minimum width: 20 feet) and shall be located adjacent a stream. In order to meet the requirements for 15A NCAC 2B .0256, the filter strip must meet the FOTG 393 specifications under “General Criteria” and “Additional Criteria to Reduce Sediment, Particulate Organics, and Sediment-Adsorbed Contaminant Loadings in Runoff”.

Excluded Riparian Herbaceous Cover:
Riparian herbaceous cover must follow the species listed in and the density requirements of the USDA – Natural Resources Conservation Service Field Office Technical Guide for North Carolina (FOTG) no. 390, Riparian Herbaceous Cover, except that the width must be 30 feet and shall be located adjacent to a stream. In order to meet the requirements for 15A NCAC 2B .0256, the riparian herbaceous cover must meet the FOTG 390 specifications under “General Criteria” and “Additional Criteria to Protect or Improve Water Quality.

Excluded Field Border:
A field border must follow the USDA – Natural Resources Conservation Service Field Office Technical Guide for North Carolina (FOTG) no. 386, Field Border except that the width must be 30 feet and shall be located adjacent to a stream.

Excluded Conservation Cover:
Conservation cover must follow the species listed in and the density requirements of the USDA – Natural Resources Conservation Service Field Office Technical Guide for North Carolina (FOTG) no. 327, Conservation Cover except that the width must be 30 feet. Use the specifications guide for either Wildlife Plantings (327-II) or Grasses and Legumes (327-III) and locate the practice adjacent to a stream.

Excluded Forested Buffer Strip:
The practice shall consist of a forested buffer strip located adjacent to an intermittent or perennial stream. The forested buffer strip shall start at the normal water line or top of channel bank of the ditch or water body and extend a minimum distance of 20 feet measured horizontally on a line perpendicular to the stream. Dominant vegetation shall consist of existing, naturally regenerated, or planted trees and shrubs suited to the site and with a minimum width of 20 feet. In order to meet the requirements for 15A NCAC 2B .0256, the forested buffer strip shall meet density specifications for plant type, height and spacing in FOTG 391 under “General Criteria Applicable to All Purposes.” Use the specifications guide for trees (327-I) and locate the practice adjacent to the intermittent or perennial stream.

Excluded Combined Forested and Herbaceous Buffer Strip:
The practice shall consist of a combined forested and herbaceous buffer strip, a minimum of 50 feet, located adjacent to a stream. The combined forested and herbaceous buffer shall be two strips. The forested strip shall start at the normal water line or top of channel bank of the stream and extend a minimum distance of 30 feet measured horizontally on a line perpendicular to the stream. The herbaceous strip, starting at the landward edge of the forested strip, shall extend an additional distance, measured in the same manner as the forested strip, so that the total minimum width of both strips is 50 feet. The herbaceous strip may contain trees or shrubs. Dominant vegetation in the forested strip (minimum 30 feet) shall consist of existing, naturally regenerated, or planted trees and shrubs suited to the site. In order to meet the requirements for 15A NCAC 2B .0256, the forested strip shall meet the species and planting density requirements listed in the USDA – Natural Resources Conservation Service Field Office Technical Guide for North Carolina (FOTG) code 391, Riparian Forest Buffer under “General Criteria Applicable to All Purposes”, using the specifications guide for trees (327-I). The herbaceous strip may include existing, naturally generated vegetation, or shall follow the vegetation type, establishment, and maintenance requirements of USDA – NRCS FOTG codes 386 Field Border, 390 Riparian Herbaceous Cover, 393 Filter Strip or 512 Pasture and Hayland Planting.

Maintenance:
The practice must be maintained according to the purpose and the performance objectives. Grazing to control vegetation or for any other purpose is not allowed in the excluded riparian buffer practice. Persons subject to the Tar-Pamlico agricultural rule shall be responsible for implementing and maintaining each BMP used to meet the requirements of this rule for as long as they continue their agricultural operation (15 A NCAC 2B .0256 (d)). However, operators may change to other BMPs approved by the SWCC but these BMPs, in turn, must also be maintained. The Division of Water Quality is ultimately responsible for enforcing the maintenance requirements of the BMPs used to meet the requirements of the rule (15 A NCAC 2B .0256). Operators must be able to demonstrate to DWQ that the performance objectives are being met for as long as they continue their agricultural operation.

Point Value Calculation:
Point values are assigned to excluded buffer practices on a site-specific basis. The following concepts guide the calculation of point credit for a practice. A technical note with calculation details is attached.

•In general, credit is given for two elements of excluded buffers – preventing direct waste deposition into the stream (stream exclusion credit), and intercepting and removing some of the nutrients coming off of the pasture (excluded buffer credit). The two elements are not automatically credited together – they will occur together to varying degrees on different operations, and are credited accordingly.

• Excluded buffer credit can be calculated independently of stream exclusion credit. Exclusion credit may or may not apply to the pasture unit even though the buffer must be fully excluded from cattle access. The attached technical document illustrates this point. Points for the buffer are calculated based on percentage reduction of the 4.6 nitrogen lb/acre/year from nutrient export as a fraction of the total export from pasture of 6.76 lb of N/acre/year.

• Nitrogen inputs to any stream on an operation can contribute to the overall nitrogen load to the basin. Therefore, exclusion credit can only be claimed for a unit if cattle are excluded from all streams in that unit.

• Buffer credit is based on removal of soluble nitrogen by the buffer zone from shallow groundwater flows leaving the pasture. Buffer percent nitrogen reduction values have been established as shown in the table below. These values are valid only for excluded buffers. The buffer percent nitrogen reduction is applied only to the area that drains through the buffer practice, which may differ from the area of the pasture unit.

• The table below illustrates the points calculation process for each type of excluded buffer independent of stream exclusion. Stream exclusion would yield additional points when it is provided for a pasture unit (see attached technical note, which provides full calculation details). The point totals shown below are the maximum possible for the excluded buffer portion of the calculation. Where less than the entire pasture unit drains through the buffer, the buffer points below would be reduced by the fraction of the pasture that drains through the buffer.

• Most farms have multiple pastures and may claim different practices in various pastures. Pastures can be treated as individual units, with proportional point assignments depending on acreage and animal grazing days spent in each pasture unit. A single weighted average point value can then be calculated for the entire operation (see attached technical note, which provides calculation details). Excluded Riparian Buffer Practice Options (and Minimum Width) % N Reduction Used to Calculate Points, % Calculation and Maximum Points for Excluded Buffer Part of Calculation (Points awarded to the buffer independent of stream exclusion credit)Excluded Filter Strip ( 20’)404.6 * 40%/ 6.76 = 27 pts.Excluded Forested Buffer Strip ( 20’) 75 4.6 * 75% / 6.76 = 51 pts.Excluded Riparian Herbaceous Cover, Excluded Field Border, Excluded Conservation Cover ( 30’) 65 4.6 * 65% / 6.76 = 44 pts.Excluded Combined Forested and Herbaceous Buffer ( 50’)85 4.6 * 85% / 6.76 = 58 pts.