Water: Coastal Zone Act Reauthorization Amendments
G. Fire Management
Prescribe fire for site preparation and control or suppress wildfire in a manner which reduces potential nonpoint source pollution of surface waters:
- Intense prescribed fire should not cause excessive sedimentation due to the combined effect of removal of canopy species and the loss of soil-binding ability of subcanopy and herbaceous vegetation roots, especially in SMAs, in streamside vegetation for small ephemeral drainages, or on very steep slopes.
- Prescriptions for prescribed fire should protect against excessive erosion or sedimentation to the extent practicable.
- All bladed firelines, for prescribed fire and wildfire, should be plowed on contour or stabilized with water bars and/or other appropriate techniques if needed to control excessive sedimentation or erosion of the fireline.
- Wildfire suppression and rehabilitation should consider possible NPS pollution of watercourses, while recognizing the safety and operational priorities of fighting wildfires.
This management measure pertains to lands where silvicultural or forestry operations are planned or conducted. It is intended to apply to all prescribed burning conducted as part of normal silvicultural activities on harvested units larger than 5 acres and for wildfire suppression and rehabilitation on forest lands.
Under the Coastal Zone Act Reauthorization Amendments of 1990, States are subject to a number of requirements as they develop coastal nonpoint source programs in conformity with this measure and will have some flexibility in doing so. The application of this management measure by States is described more fully in Coastal Nonpoint Pollution Control Program: Program Development and Approval Guidance, published jointly by the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce.
The goal of this management measure is to minimize potential NPS pollution and erosion resulting from prescribed fire for site preparation and from the methods used for wildfire control or suppression.
Prescribed burning is aimed at reducing slash and competition for nutrients among seedlings and protecting against wildfire. Slash burning destroys vegetation that reduces nitrogen-nitrate loadings. If uncontrolled, the burn may reach SMAs or highly erodible soils, causing increased sedimentation and erosion. Prescribed burning causes changes in the chemical cycling of elements by influencing biological and microclimate changes, volatilization, and mineralization processes.
The intensity and severity of burning and the proportion of the watershed burned are the major factors affecting the influence of prescribed burning on streamflow and water quality (Baker, 1990). Fires that burn intensely on steep slopes close to streams and that remove most of the forest floor and litter down to the mineral soil are most likely to adversely affect water quality (Golden et al., 1984). The amount of erosion following a fire depends on the following:
- Amount of ground cover remaining on the soil;
- Steepness of slope;
- Time, amount, and intensity of rainfall;
- Intensity of fire;
- Inherent erodibility of the soil; and
- Rapidity of revegetation.
Mersereau and Dyrness (1972) found slash burning on steep slopes to contribute to surface soil movement by removing litter and vegetation, and baring 55 percent of the mineral soil. Richter and others (1982), however, found that periodic, low-intensity prescribed fires had little effect on water quality in the Atlantic and Gulf coastal plain. Revegetation of burned areas also drastically reduces sediment yield from prescribed burning and wildfires (Baker, 1990).
3. Management Measure Selection
This measure is based in part on information and experience gained from studies and from the use of similar management practices by States. To avoid many of the negative impacts from prescribed burning, Pope (1978) recommends that those in charge of managing the fire construct water diversions on firelines in steep terrain to drain the water away from the burn, leave an adequate strip of undisturbed surface between the prescribed burn area and water sources, and avoid intense fires on soils that are uncohesive and highly erodible.
Dyrness (1963) studied the effects of slash burning in the Pacific Northwest, finding that severe burning decreases soil porosity and infiltration capacity, thus increasing the potential for soil erosion. Clayton (1981) found that after the helicopter logging and broadcast burning of slash in the Idaho batholith, erosion increased approximately 10 times the natural rate for a short period of time as the result of to a high-intensity rain storm and then decreased substantially within the following year.
Feller (1981) examined the effects of (1) clearcutting and (2) clearcutting and slash burning on stream temperatures in southwestern British Columbia. Both treatments resulted in increased summer temperatures as well as daily temperature fluctuations. These effects lasted for 7 years in the case of the clearcut stream but longer in the case of the clearcut and slash-burned stream. Clearcutting increased winter temperatures, while slash burning decreased temperatures. The study concluded that clearcutting and slash burning had a greater impact on stream temperatures than did clearcutting alone.
Biswell and Schultz (1957) found that surface runoff and erosion in northern California ponderosa pine forests are not attributable to prescribed burning. While conducting observations during heavy rains, the authors found that the duff and debris left after burning were effective in maintaining high infiltration and percolation capacity, and they traced surface runoff to bare soil areas caused by human activity. A study by Page and Lindenmuth (1971) examined the effects of prescribed fire on vegetation and sediment on a watershed in the oak-mountain mahogany chaparral of central Arizona. The study found that the average sediment movement from the treated drainages during the 5-year period was 0.30 acre-feet per square mile per year, which is substantially less than the sediment loss of 3.2 acre-feet per square mile per year for the first 5 years following a wildfire in a comparable area in Arizona.
Stednick and others (1982) found increased concentrations of suspended sediments, phosphorus, and potassium in streamflows below the burned area after the slash burning of coastal hemlock-spruce forests of southeastern Alaska. Stream monitoring indicated an immediate flush of elements, followed by a slower release of these elements into surface water. No reduction in the nitrogen content or depth of the soil organic horizon was found, but there were significant reductions in the potassium and magnesium contents of the soil.
Minnesota's Landowner Forest Stewardship Plan (1991) estimates the cost for prescribed burning to be $27/acre.
As discussed more fully at the beginning of this chapter and in Chapter 1, the following practices are described for illustrative purposes only. State programs need not require implementation of these practices. However, as a practical matter, EPA anticipates that the management measure set forth above generally will be implemented by applying one or more management practices appropriate to the source, location, and climate. The practices set forth below have been found by EPA to be representative of the types of practices that can be applied successfully to achieve the management measure described above.
a. Prescribed Fire Practices
- Carefully plan burning to adhere to weather, time of year, and fuel conditions that will help achieve the desired results and minimize impacts on water quality.
Evaluate ground conditions to control the pattern and timing of the burn.
- Intense prescribed fire for site preparation should not be conducted in the SMA.
- Piling and burning for slash removal purposes should not be conducted in the SMA.
- Avoid construction of firelines in the SMA.
- In prescriptions for burns, avoid conditions requiring extensive blading of firelines by heavy equipment.
Use handlines, firebreaks, and hose lays to minimize blading of firelines.
- Use natural or in-place barriers (e.g., roads, streams, lakes, wetlands) as an acceptable way to minimize the need for fireline construction in situations where artificial construction of firelines will result in excessive erosion and sedimentation.
- Construct firelines in a manner that minimizes erosion and sedimentation and prevents runoff from directly entering watercourses.
- Locate firelines on the contour whenever possible, and avoid straight uphill-downhill placement.
- Install grades, ditches, and water bars while the line is being constructed.
- Install water bars on any fireline running up and down the slope, and direct runoff onto a filter strip or sideslope, not into a drainage (Huff and Deal, 1982).
- Construct firelines at a grade of 10 percent or less where possible.
- Adequately cross-ditch all firelines at the time of construction (Megahan, 1983).
- Construct simple diversion ditches or turnouts at intervals as needed to direct surface water off the plowed line and onto undisturbed forest cover for dispersion of water and soil particles.
- Construct firelines only as deep and wide as necessary to control the spread of the fire.
- Revegetate firelines with adapted herbaceous species (Megahan, 1983).
Refer to the Revegetation of Disturbed Areas management measure for more detailed information.
- Execute the burn with a trained crew and avoid intense burning.
Intense burning can accelerate erosion by consuming the organic cover.
- Avoid burning on steep slopes with high-erosion-hazard areas or highly erodible soils.
b. Wildfire Practices
- Whenever possible avoid using fire-retardant chemicals in SMAs and over watercourses, and prevent their runoff into watercourses. Do not clean application equipment in watercourses or locations that drain into watercourses.
- Close water wells excavated for wildfire-suppression activities as soon as practical following fire control.
- Provide advance planning and training for firefighters that considers water quality impacts when fighting wildfires. This can include increasing awareness so direct application of fire retardants to waterbodies is avoided and firelines are placed in the least detrimental position.