Forest Water Quality Part 1 – Keeping Water Clean

Forest Water Quality Part 1 – Keeping Water Clean


♪ There’s some truth in the
saying that Idaho is what
America was. From the lakes and forests of
the panhandle, to the mountains
of central Idaho, to the
irrigated farms and arid
rangelands of the south, Idaho’s natural beauty and
abundant resources still retain
the promise and possibility of
the American frontier. Among all of Idaho’s natural
gifts, our single most important
resource, the one that ties all
the others together, is water. And one of the most important
elements for maintaining Idaho’s
water quality and quantity is
forests. Forests cover more than forty
percent of Idaho. Idaho forests provide wildlife
habitat, recreation, a renewable
source of forest products, and
many other values. Forests receive more rain and
snow than non-forested areas. That’s part of the reason trees
grow there. This water does more than grow
trees. It eventually forms streams
which join together to form
rivers and lakes that provide
waterfor drinking and household
needs, for agriculture, fisheries, and
recreation. Through all these uses, Idaho
uses over 17 billion gallons of
water per day. Water from forests is
particularly valuable because it
is so clean. Clean water is essential to
Idaho’s economy and quality of
life. The majority of forested land
in Idaho is federally owned. However, eleven percent of Idaho
forests are owned by thousands
of farmers, ranchers, and other
family forest owners. Our forest activities, as well
as development, agriculture, and
other land uses often affect
water quality and quantity. The first segment of this
program will describe how water
moves through the forest, how our forest activities can
affect that water, and what landowners and
operators can do to enhance
forest water quality. In part two, we’ll outline the
Idaho Forest Practices Act, a state law that sets minimum
“Best Management Practices” to guide forest management
activities that can affect water
quality. ♪ Forests receive the highest
precipitation rates in Idaho, ranging from fifteen to thirty
inches a year in drier Idaho
forests, to over sixty inches in high
elevation forests. The precipitation on most family
forests ranges between 15 and 40
inches annually. Most of this precipitation falls
in the winter as snow. Water from rain and snow moves
through the forest in many ways. Some of the water evaporates
from tree crowns before it ever
reaches the ground. Some of it enters the soil
where it is absorbed and used by
plants, fungi and soil
organisms. After the ground has absorbed
all it can, some of the water
flows above and below ground to
an aquifer, to a wetland, or to
streams. Looking at a broader, landscape
level, much of the water moving
through a forest moves first to
“ephemeral areas” that collect
water temporarily, and into
intermittent, or seasonal,
streams. Intermittent streams in turn
drain into perennial, or
year-round streams or wetlands. As we get closer to areas where
water is more concentrated, from
ephemeral areas, to wetlands and
streams, we come to riparian
zones. A healthy riparian zone
supports a diverse web of
vegetation and wildlife. The lush vegetation in a
riparian zone provides water,
cover, and travel corridors for
forest animals. It shades water, keeping it
cool for fish. Riparian vegetation also helps
stabilize stream banks during
high water flows and traps
sediment, keeping it out of streams while
integrating it into stream
banks. Over time trees in riparian
zones fall into streams and
provide large organic debris
which creates pools for fish
habitat. As water moves to ephemeral
areas and on to ever larger
streams it leaves the area at
one point: a stream or outlet
that marks its watershed. A watershed is a land area term
used to describe water quantity
and quality. Different watersheds are nested
inside each other, depending on
the stream being referred to. For example, the Marble Creek
watershed is nested in the St.
Joe River watershed, which in turn is nested in the
Spokane River watershed. Ultimately, most of Idaho’s
water drains to the Columbia
River watershed. ♪
Tomorrow” We receive many benefits from
Idaho’s forests: forest products and the jobs
that go with them, land for homesites, wildlife
habitat, beautiful environments
for recreation. In the pursuit of these
benefits we sometimes alter the
forest, which can affect water
that moves through forests. Water that flows over the top
of the soil surface has the most
potential impact on forest water
quality. As water moves downhill over the
soil surface, gravity gives it
energy. In undisturbed forests, this
energy is dissipated by
vegetation and debris on the
forest floor and in riparian
areas. This gives the water time to
soak into the soil — a process
known as infiltration– and
little soil erosion occurs. Water quality is relatively
high. However if soil is bare,
infiltration is reduced, and the
energy of moving water can
dislodge soil and carry it
downhill, especially during the first few
years after soil is exposed. Some of this soil resettles
elsewhere on the forest floor. Some of it eventually winds up
in streams, where it either
falls to the bottom, or is deposited as sediment on
streams banks during high water. The amount of erosion that
occurs and the resulting
sediment that reaches the stream
are often higher when rainfall
is heavy, or when rain falls on snow,
causing faster snow melt, and
more total water. More water means more energy to
dislodge and move soil. Some erosion and sedimentation
is natural. However, if the forest is
heavily disturbed, either
naturally, by a fire or a slump,
or by our activities, the amount of sediment can
increase greatly. The primary sources of sediment
from forest activities are roads
and trails, whether they’re used to harvest
timber, access home sites, or
to recreate. These activities take on even
greater significance closer to
the stream. Heavily disturbed riparian areas
lose some of their ability to
filter sediment before it
reaches the stream. You might think that one or two
forest roads wouldn’t harm
forest water quality, and you
might be right. But when a large number of
seemingly separate timber
harvests, housing developments,
fires, or other disturbances,
occur within a few years across
the same watershed, the effect of all them added
together, the cumulative effect,
can reduce forest water quality. What is the cost? High sediment concentrations in
streams make water less
drinkable and increase treatment
costs. Sediment deposited in a
streambed damages habitat for
fish, such as cutthroat trout,
and aquatic organisms which need
relatively clean gravel to
reproduce. Sediment also carries
nutrients, too much of which can
reduce water quality in lakes. Sediment that accumulates in
reservoirs shortens their life
and is expensive to remove. Most forest soil erosion and
sediment deposition occurs
during a handful of large rain
or snow melt “events”. The best way to enhance forest
water quality is to plan and
implement forest roads and other
disturbances so the resulting modifications
on the forest minimize erosion
and sedimentation during these
peak events. Forest practices have improved
considerably over the last fifty
years. But as forests receive more
intensive use, greater attention
and care are required. For example: Get to know your
property. Some soils are more erodible or
less stable, than others. Locate areas on your property
that are especially vulnerable
to erosion. These are the areas to watch in
future forest activities. Look for landslides or slumps,
and check soil survey maps if
available. Put together a forest
management plan. A written forest management plan
helps frame decisions affecting
water quality and other forest
values. It also improves communication
with loggers and others working
on a property. Keep as little area in roads
and skid trails as possible. Roads and skid trails are more
prone to erosion. They also remove valuable forest
land. The less mileage and width in
roads and skid trials, the
better. If you or your neighbors are
building roads, try to
communicate with each other to see how you can cooperate to
create more efficient road
systems that are beneficial for
everyone in the area. Build roads in stable places,
away from riparian zones. When possible, build roads along
contours on ridges rather than
drainages or near riparian areas and away from highly erodible or
slump prone areas. Keep new road grades at less
than eight percent if possible. Plan roads and skid trails for
future harvests. Well-planned roads and
designated skid trails can be
used for future harvests as
well, avoiding new erosion. Build adequate drainage into
roads. Forest roads act as a water
drainage network. Specific drainage structures
such as rolling dips, water
bars, and culverts, divert water
from the road quickly. This prevents erosion and
saturation, which can lead to
road failure. Be sure to prepare for those
times when the most rain tends
to fall on the particular site,
such as rain-on-snow events. Use the least disturbing
logging methods practicable for
the harvest and reforestation. For example, Minimize the area in skid
trails and landings. Avoid making steep skid trails. Wet soils are more vulnerable
to compaction and disturbance. Compaction usually reduces tree
growth and reduces water
infiltration. Try to log when soils are either
dry or frozen. Less-disturbing logging methods
also save nutrients and help
soil retain moisture for future
trees. Get a written contract for
timber sales. Although the Idaho Forest
Practices Act sets minimum
standards for maintaining forest
water quality during timber
harvest, thinning, and other
forest management practices, written timber sale contracts
can be used to build further
incentives to enhance water
quality. ♪ Forest water quality protection
is not over when a harvest is
complete. Maintain forest roads. Normally, forest roads stabilize
after a few years if they are
well planned, constructed, and
maintained. Maintaining roads lessens
erosion and keeps them useful
for the future. Clean out culverts, water bars,
and other water drainage
structures. Drainage structures may wear
down or fill up with debris, so
they should be cleaned out or
repaired regularly. If current drainage is
inadequate, install new or
additional structures. Be sure to check road drainage
during the winter and early
spring thaws as well. Close roads seasonally or
permanently. Roads not in use should be
closed to prevent impact, at
least during wet seasons when
they are most vulnerable. For access during fire season or
other times of the year, put in
gates. Don’t overburden roads. If a road was designed for light
loads, or temporary use, heavy
equipment or traffic may stress
the road and lead to failure. Don’t assume that an old
logging road will be suitable
for home site development. It may require considerable
improvements for the new use, or
it might be better to construct
an entirely new road. If you’re considering using an
old logging road or skid trail
for a home site, contact a
professional engineer to help
you evaluate whether the road is
suitable. Add rock to road surfaces. Adding rock to heavily used
roads reduces erosion, allows
use during wet seasons, and
increases road efficiency. This may also increase the value
of your timber by making it more
accessible than sites with less
prepared roads. Seed grass and legumes. Seeding road cuts, and fill
slopes, skid trails, and other
bare areas holds the soil and
benefits wildlife. Plant willows or alders along
stream banks. Woody plantings stabilize stream
banks, intercept sediment, slow
the stream during high water
flows, and provide shade for
fish and other wildlife. Limit recreational use. Stay
on established trails. Don’t cut across established
switchbacks. Avoid those areas where
sediment from erosion may end up
in streams. Evaluate grazing in riparian
areas. Riparian areas produce a lot of
high quality forage. But if they’re grazed too
heavily or at the wrong time of
year, added stream bank erosion
can result. Be careful when mixing
potentially toxic materials. Avoid mixing or using
pesticides, fertilizers,
petroleum products and similar
materials near riparian areas. ♪ Much of what makes Idaho great
comes either directly or
indirectly from our abundant
forests. To maintain and enhance this
natural heritage, we must
carefully steward Idaho’s
forests. Management practices change as
we learn more about the effects
of natural and man-made
disturbances on forest water
quality. This program is only an
introduction. Several agencies can provide
assistance to help you better
manage your forest land for high
water quality. Many forest management
practices are regulated to
comply with best management
practices outlined in the Idaho
Forest Practices Act. The Idaho Department of Lands —
IDL — employs “Forest Practice
Advisors” who inspect harvests
and other forest activities for
compliance with the Idaho Forest
Practices Act. FPA advisors provide on-site
technical assistance to private
forest landowners and operators. The Natural Resources
Conservation Service provides
technical assistance related to
soil erosion and conservation
planning. They also conduct soil surveys,
which may help you identify
areas of special risk related to
forest water quality. The NRCS and Idaho Soil and
Water Conservation Districts
also administer financial
assistance programs for
landowners interested in
applying conservation measures
on their property. Keep in mind that funds are not
available if the measures are
required to comply with the
Idaho Forest Practices Act. Finally, University of Idaho
Extension offers a wide variety
of publications, workshops, and
other educational programs
designed to strengthen
landowner’s skills related to
forest and natural resource
management. Check your local listings under
“University” or “County.” Keeping sediment out of streams
is vital to maintaining the
natural resources all Idahoans
cherish. The best way to keep forest
water clean is to manage our
forests with care. Remember, no single landowner
works alone. Individual practices, and
individual decisions, play a
cumulative part in the quality
of water throughout the state. Each of us must steward
forestland, to make sure that
Idaho remains economically
strong and naturally beautiful. ♪

Leave a Reply

Your email address will not be published. Required fields are marked *