Minimizing the Effects of Timber Harvest and Forest Roads on Water Quantity
& Quality in Oregon
In Oregon forests, potential logging impacts are reduced by Forest Practices Act
regulations which limit the size and placement of harvest units, specify road standards,
and require that buffer strips be left in stream corridors. These tree-filled buffer
strips provide cover for fish, and help shade streams from the hot summer sun.
Where harvesting is concerning, the enemy is erosion, chiefly in the form of landslides.
While logging activities are frequently seen as a source of landslides, soils scientists
and hydrologists tell us old roads -- built under outdated standards -- are more
of a problem than is the actual harvest. Much has been done to upgrade road construction
standards, and new forest roads are much less of a problem than are roads built
years ago. Of course there is always room for improvement, but we've learned a great
deal about where to build roads and where not to build them.
While rarely viewed in these terms, water is indeed a forest product. Almost all
municipal water originates in forests, and in the West, almost 70 percent of useable
water comes from managed forests -- many such forests where harvest occurs. And
water itself can be a casualty of catastrophic natural disturbances, including wildfires
that leave soil exposed to severe erosion.
Across the nation, more than 130 water companies manage their own forest lands for
the domestic water they provide for communities served. In fact, forestry, timber
harvest, and watershed management were intertwined disciplines as far back as 1500
B.C. when the Chinese began altering their forests to regulate stream flows into
irrigated fields. In 1897, our own Congress cited watershed management as one of
the chief reasons for establishing the national forest system. Today, virtually
every community in the Pacific Northwest gets its water from watersheds that begin
in national forests -- where timber harvest has successfully co-existed with clean
water in some areas as long as 100 years.
Below are some other facts about Oregon forest law you may find interesting.
A Brief Water History of the Oregon Forest Practices Act:
1941:--State adopts Oregon Forest Conservation Act. Reforestation and fire protection
are primary objectives, although erosion control is also an objective.
1971:--With industry support, Oregon legislature approves nation's first Forest
Practices Act. New law sets minimum standards for stream protection, reforestation,
road construction and maintenance, timber harvesting, chemical applications and
slash disposal. Legislation governs private and state lands. Emphasis is on prevention
of problems and encouraging private forest stewardship. Law becomes a model for
1972-1985:--State Board of Forestry adopts additional rules aimed at minimizing
soil erosion, disturbance, landslides, and stream impacts.
1987:--Riparian protection rules amended to require larger stream and wetland buffer
1990:--Oregon Forest Industries Council proposes major reforms designed to strengthen
protection for water quality, streams, reforestation, clear-cut limits, and snag
and green-tree retention.
1991:--Legislature instructs Board of Forestry and state Department of Forestry
to revise stream protection rules. Objective is to provide equal protection for
fish present in all Oregon streams.
1995:--New stream protection rules are implemented. Streamside objectives include
creating forest conditions present in natural timber stands 80 to 200 years old,
lower water temperatures, easier upstream fish passage, increased amount of in-stream
large woody debris and increased fish survival. In time, more streamside trees will
provide better habitat for fish.
2001:-- Again, with forest industry support, the Oregon Legislature instructed a
revision of the Forest Practices Rules to address protection of public safety from
rapidly moving landslides that can originate from forests. Harvesting and road building
operations upslope from highways and residences may be modified, where there is
a public safety risk due to potential landslides.
2003:-- New forest road rules are implemented. Improved road objectives include
wet weather road use standards that would prevent muddy water delivery from operation
roads to Oregon forested streams.
Studies Examine Possible Water Updates to Forestry Rules:
In 1994 and 1997, the Oregon State University Forest Engineering Department completed
important reviews of scientific studies related to timber harvesting effects on
water quality and quantity in the Pacific Northwest.
The reviews were commissioned by the Oregon Forest Resources Institute and conducted
by Dr. Paul W. Adams, a department professor and forest watershed specialist. The
reviews summarize the findings of nearly 100 published studies of the effects of
logging and forest roads on water quality and quantity.
Public interest in watershed-related issues is high in the Pacific Northwest, and
many believe forest road construction and logging are major causes of flooding,
erosion and declines in both salmon habitat and the number of migrating salmon.
But Dr. Adams' review of available scientific literature dating back to 1959 reveals
"insignificant, positive, negative and combined effects that were greatly influenced
by the specific location, treatments and duration of study."
In other words, while logging and forest road construction do indeed have localized
short-term impacts on water quality and quantity, there is no evidence these impacts
are widespread or longstanding. Several studies Dr. Adams reviewed point to increased
peak stream flows during rainy or snowmelt periods after timber harvesting, but
these effects are more closely linked to heavy rains than to logging itself.
Moreover, Dr. Adams noted, "stream flow increases after logging, become smaller
with time, eventually disappearing when the canopy of the replanted forest begins
losing as much water to the atmosphere as the original forest."
Water quality and quantity impacts are more prevalent in areas where logging and
road construction activities occupy a comparatively large portion of the total watershed.
In larger watersheds, "little or no effect on stream flow is expected"
because individual logging operations affect an area that is small when compared
to the overall size of the watershed.
Although the studies Dr. Adams reviewed appear to minimize the long-term impacts
of logging and road construction, he was quick to point out that studies conducted
in the 1960s led to changes in the Oregon Forest Practices Act, restricting or prohibiting
the removal of streamside vegetation which helps hold soil, while insulating streams
against summer and winter temperature extremes.
Although logging systems in use then were often blamed for declining water quality
and quantity, Dr. Adams wrote that many studies did not clearly distinguish between
logging impacts and those related to outdated road construction, slash burning or
stream cleanup rules in effect in the 1960s, 1970s and 1980s.
Research suggests that the widespread practice of stream clean-up (removing woody
debris to enhance fish passage, etc.), promoted during this period by fish biologists,
also may have contributed to channel erosion and sedimentation. Adams wrote, "Where
water quality measurements continued for several years, sediment levels generally
declined or disappeared as re-vegetation and other stabilization occurred. Where
patch cutting or harvest layout maintained streamside vegetation, increases in stream
sediment generally were significantly reduced or avoided."
Beyond regulatory changes that grew out of 30-plus years of watershed studies, improved
technology has also played a central role in maintaining water quality and quantity.
New road construction techniques and design changes in logging equipment provide
an added measure of protection for watersheds.
The studies Dr. Adams reviewed also evaluated changes in water chemistry in areas
where logging had occurred. Again, minimal, short-term impacts were observed, and
these were partly the result of slash burning, less commonly conducted as a pre-reforestation
"Nutrient increases generally declined within a few years as re-vegetation
occurred," Dr. Adams wrote, "and in some cases nutrient concentrations
eventually became lower in treated areas, presumably due to the heavy uptake of
nutrients by young, rapidly growing vegetation."
The studies Dr. Adams reviewed were conducted by scientists from several western
universities, as well as the U.S. Forest Service and the Bureau of Land Management.
Their findings were subsequently published in several scientific journals including
the Journal of Forestry, Canadian Journal of Forest Research, Western Journal of
Applied Forestry, and Northwest Science. Copies of the reviews are available at
Oregon State University, Forest Engineering Department or Oregon Forest Resources
The sum result of these reviews of current research and Oregon's forest practices
will be three-fold:
- Reaffirm successes of existing updated forest stream rules and related rules.
- Identify forest rule enhancements to better protect water resources -- recommended
for adoption by the Oregon legislature into Oregon Forest Practice Rules.
- Dispel unfounded allegations concerning watershed damage due to forest practices,
as well as dismiss ineffective protection schemes.