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:: Home > The Forest > Logging > Hot Topic: Logging & Water Quality

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?

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.

 

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...
... 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).
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.
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).
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.
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.