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> The Forest > Logging > Hot Topic: Logging & Water Quality
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There is no doubt that land use
by humans, whether it is plowing an agricultural field,
bulldozing a terrace for a house, or harvesting trees
from a forest, changes the way water is captured,
stored, and released by vegetation and soil. But for
each activity, different techniques can affects the
forest's water resources in different ways.
The folks who plan harvest units
and logging roads, and those who do the logging and
build the roads, try to take action in a way that
has the least possible negative impact, while still
achieving their goals. The goal in this particular
case is harvesting timber and building a road to transport
that timber from the forest to the mill.
So what actions can minimize the
negative effects on water quality?
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Clearcutting.
This reproduction method
typically produces the largest and most diverse changes
in water quality for the first few years after the
logging. We we can choose alternative methods when
possible, especially in sensitive areas.
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We know that landslides
are one of the natural processes of erosion, and given
the right circumstances they can even occur on heavily
forested hillsides (right: a slide on a forested slope).
Landslides can carry a lot of sediment into streams...
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... and
road-building and timber harvesting both appear to be
capable of setting the stage for a landslide to occur
(left: a landslide on the steep face of a regenerating
clearcut, just above a road). |
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Erosion control
is easiest when the disturbance to the forest floor
is minimized. In sensitive areas we can use cable
logging instead of ground-based logging. If we do
choose to use ground equipment, we can take care to
minimize the amount of soil that is disturbed through
strategies like designating skid trails.
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The greatest
water quality problem is erosion from road construction
and poor maintenance of forest roads. Generally speaking,
the higher quality a road, the less the erosion potential.
A road that is well-located, appropriately surfaced,
and well-drained, is our best bet. Temporary roads can
be ripped up after use, or permanent drainage can be
created to avoid washouts (left). |
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Covering a slope
with vegetation will hold the soil in place, reducing
the erosion of loose soils. This works on the cuts
of a forest road (right: covered in grasses), and
the same technique can be used in harvest units—
plants that remain after a harvest help hold the soil.
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While
some erosion is inevitable during the rainy season,
the way we manage our activities in the forests can
either increase or decrease the erosion that occurs.
Planning our activities well, building good roads, and
preparing for the inevitable Oregon wet weather are
some things that we can do to reduce the amount of erosion
that makes it to our streams. |
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