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Wood is Good

Photo Credit: Jason Blakney, Montana Fish, Wildlife & Parks

March 2, 2021
By Brita Olson

As Sanders County residents continue to recover from January’s severe windstorm, remember that
wood is beneficial for our streams and rivers.
The storm left many residents with power outages, damaged homes and businesses, and uprooted
countless trees. Inevitably, many of these trees have fallen into our rivers, streams and creeks.
It may seem natural to extend the efforts of cleaning up property damage to our waterways. However,
logs and limbs that we don’t want on buildings and fences provide important habitat for fish and wildlife
when they fall in and along streams.
When trees fall into flowing water, they can shift the direction and velocity of the current. Often, pools
form by water scouring over or under pieces of large wood embedded in the stream channel or on the
bank. The deepest part of the river channel may shift as a result of new wood additions.
The river may increase in length and become more sinuous and meandering. Changes in velocity caused
by the water flowing over the wood may result in sediment deposition and gravel sorting. All in all, the
addition of wood creates a more diverse and complex river channel.
“Stream ecosystems are complex and woody debris, large and small, is an important habitat
component for many reasons,” says Jason Blakney, Montana Fish, Wildlife & Parks Fisheries
“Wood in streams helps to trap gravel which is used for fish spawning; facilitates pool scour;
provides habitat complexity, cover and overwinter habitat for fish by increasing depth and
reducing stream velocity; and enables retention of organic debris such as leaves, which are
important for some species of aquatic insects. Wood decays very slowly when submerged and large
trees may take hundreds of years to break down, meaning they can improve stream ecosystem function
long beyond our time”.
In the aftermath of a strong windstorm like the one that we experienced in mid-January, it may be
tempting to “clean up” streams that look messy or disturbed. However, this “messiness” is a natural
process that creates and maintains habitats for fish and wildlife.
Of course, there are circumstances where woody debris may threaten a bridge, irrigation diversion or
other infrastructure. If you have a concern about wood in a creek, stream or river, contact your local
conservation district and consult with natural resource managers first. Any removal of wood from a
stream or streambank requires a 310 permit which can be obtained from your local conservation
Green Mountain Conservation District, (406) 827-4833,
Eastern Sanders Conservation District, (406) 826-3751 ext. 102,

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