Firebreak plowing and water quality: general procedures for compliance with the Clean Water Act [Mar. 2009]

T he Georgia Forestry Commission is required to follow Best Management Practices (BMPs) when providing landowners with firebreak plowing services. BMPs are methods used to prevent or reduce soil erosion and water pollution as required by the federal Clean Water Act. Under the provisions of this Act, landowners can be subjected to fines of amounts up to $50,000 per day for water quality violations that occur on their proper ty.
General procedures for pre-suppression firebreaks:
1. Plan location of firebreaks. Aerial photographs, soil maps and topographic maps combined with an on-site evaluation will help identify the streams, gullies and highly erodible sites on the property. Proper planning will ensure that firebreaks are effective and environmentally sound.
GFC Ranger and landowner plan firebreak location.

2. Use natural barriers such as roads and fields as firebreaks where possible.

A woods road serves as a natural firebreak.
3. Identify Streamside Management Zones (SMZs).
SMZs are buffer strips adjacent to streams that require special management to protect water quality. They are determined based on steepness of the slope and whether the stream flow is intermittent or permanent. SMZ width may range from 20-100 feet (see Chart 1). Wider SMZs may be required for protected water supply reservoirs.

Slope Class Minimum Width of SMZ on Each Side

Perennial (ft.) Intermittent (ft.) Trout (ft.)

--------------------------------------------------------------------------------------------------

Slight (<20%)

40

20

100

--------------------------------------------------------------------------------------------------

Moderate (21-40%) 70

35

100

--------------------------------------------------------------------------------------------------

Steep (>40%)

100

50

100

Chart 1 - SMZ widths by slope class and stream type.

a. Exclude firebreaks and fire from SMZs when possible.
b. If firebreaks must be connected to a stream, construct them by using hand tools or by back-blading with a dozer in the SMZ.

Ranger back blades with dozer to minimize soil disturbance in an SMZ.
4. Install firebreaks on the contour rather than along property lines.

5. Create firebreaks with a flat blade or discharrow. These breaks erode less than plowed breaks.

6. Install water bars1 with water turnouts2 in firebreaks according to BMP recommendations (see Chart 2).
1 A water bar is a hump or small dam-type structure created to redirect surface water drainage patterns.
2 A water turnout is an extension of a firebreak water bar into a vegetated area to disperse and filter surface water runoff.

Grade of Firebreak (percent)

Distance Between Water Bars (feet)

------------------------<---2--------------------------------------------------------3--0--0---------------------

---------------------------5--------------------------------------------------------1--3--5---------------------

------------------------1---0----------------------------------------------------------8--0---------------------

------------------------1---5----------------------------------------------------------6--0---------------------

------------------------2---0----------------------------------------------------------4--5---------------------

------------------------3---0----------------------------------------------------------3--5---------------------

40*

30

Chart 2 - Spacing of water bars.
* Use grades of 40% and steeper only for short stretches.