What Are the Major Sources of
Pollutants from Forestry Operations?
Silvicultural nonpoint source pollution impacts depend on site
characteristics, climatic conditions, and the forest practice employed.
Sediment, nutrients, pesticides, and temperature are pollutants commonly
associated with forestry activities.
The objective of this management measure is to ensure that silvicultural
activities, including timber harvesting, site preparation, and associated
road construction, are conducted in a way that takes into account potential
nonpoint source pollutant delivery to surface waters. Preharvest planning
has been demonstrated to play an important role in the control of nonpoint
source pollution and efficient forest management operations. Components of
this measure address key aspects of forestry operations relevant to water
quality protection, including the timing, location, and design of harvesting
and road construction, the identification of sensitive areas or
high-erosion-hazard areas; and the potential for additional cumulative
contributions to existing water quality impairments.
STREAMSIDE MANAGEMENT AREAS (SMA)
This management measure establishes areas along surface waters that are
managed to protect the water quality of the adjacent waterbody. Streamside
Management Areas (SMAs) protect against soil disturbance and reduce the
delivery to waterbodies of sediment and nutrients from upslope activities.
Canopy species in SMAs shade waterbodies, which moderates water temperature,
and provide the detritus that often serves as an energy source for stream
ecosystems. Trees in the SMA also provide a source of large, woody debris to
Road construction is often the largest source of silviculture-produced
sediment. The purpose of this management measure is to reduce the generation
and delivery of sediment from road construction or reconstruction. This is
to be accmplished by following the preharvest plan layouts and designs for
the road system, incorporating adequate drainage structures, and properly
installing stream crossings. Other components of this measure include
avoiding constructing roads in SMAs, removing debris from streams, and
stabilizing areas of disturbed soil such as road fills.
The objective of this management measure is to manage existing roads to
prevent sedimentation and pollution from runoff-transported materials. This
management measure describes how to manage existing roads to minimize
erosion, maintain stability, and reduce the risk of failure or decreased
effectiveness of drainage structures and stream crossings. Components of
this measure include the use of inspections and maintenance actions to
prevent erosion of road surfaces and ensure the continued effectiveness of
stream crossing structures. The measure also addresses appropriate actions
for closing roads that are no longer in use.
This management measure is intended to reduce NPS pollution resulting
from timber harvesting operations. The measure includes components for the
location of landings, for the operation of groundskidding and cable yarding
equipment, and for the prevention of pollution from petroleum products.
Harvesting practices that protect water quality and soil productivity can
also reduce total mileage of roads and skid trails, lower equipment
maintenance costs, and provide better road protection and reduce road
maintenance. Appropriate skid trail location and drainage and proper
harvesting in SMAs are addressed by this measure. Erosion from the siting
and operation of timber harvest operations can be reduced by conducting
SITE PREPARATION AND FOREST REGENERATION
In some areas mechanical site preparation is of great concern for
potential impacts to water quality. This is especially true in areas that
have steep slopes on highly erodible soils, or where the site is located in
close proximity to a waterbody. Careful regeneration of harvested forest
lands is important in providing water quality protection from disturbed
soils. This management measure is intended to reduce the impacts of
mechanical site preparation and regeneration operations and to confine
on-site potential nonpoint source pollution. Components of this measure
address keeping slash materials out of drainages, operating machinery on the
contour and protecting the ground cover in ephemeral drainages and SMAs.
Prescribed burning is aimed at reducing slash and competition for
nutrients among seedlings and protecting against wildfire. Prescribed fires
that burn intensely on steep slopes in close proximity 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. The purpose of this
management measure is to reduce the potential nonpoint source pollution and
erosion resulting from prescribed fire for site preparation and from methods
for suppression of wildfire. Prescribed fires should be conducted under
conditions to avoid the loss of litter and incorporated soil organic matter.
Bladed firelines should be stabilized to prevent erosion, or practices such
as handlines, firebreaks, or hose lays should be used where possible.
REVEGETATION OF DISTURBED AREAS
Revegetation of areas of disturbed soil can successfully prevent sediment
and pollutants associated with the sediment (such as nutrients) from
entering nearby streams. The objective of this management measure is to
reduce erosion and sedimentation by the rapid revegetation of areas of soil
disturbance from harvesting and road construction. The disturbed areas to be
revegetated are those localized areas within harvest units or road systems
where mineral soil is exposed or agitated such as road cuts, fill slopes,
landing surfaces, cable corridors, or skid trails.
FOREST CHEMICAL MANAGEMENT
Chemicals used in forest management are generally pesticides
(insecticides, herbicides, and fungicides) and fertilizers. Since pesticides
may be toxic, they must be properly mixed, transported, loaded, and applied
and their containers must be properly disposed of to prevent potential
nonpoint source pollution. Fertilizers must also be properly handled and
applied since they also may be toxic or may shift surface water energy
dynamics, depending on the exposure and concentration. The objective of this
management measure is to ensure that the application of pesticides and
fertilizers does not lead to contamination of surface waters. Components of
this measure include applications by skilled workers according to label
instructions, careful prescription of the type and amount of chemical to be
applied, and the use of buffer areas for surface waters to prevent direct
application or deposition.
WETLAND FOREST MANAGEMENT
Forested wetlands provide many beneficial water quality functions and
provide habitat for aquatic life. The purpose of this management measure is
to protect the aquatic functions of forested wetlands