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I will be speaking today from two perspectives:
-My
professional background is in hydrology, geomorphology, and fisheries
habitat.
As part of my job, I design
and construct LWD jams in streams and rivers
-Running rivers is one of my
free-time passions.
I hunt and fish on
class II and III rivers and spend another 20 - 30 days a year running class IV
and V whitewater throughout the Pacific Northwest and California.
Greater-than or equal-to 2.0m (6.6’) and
greater-than or equal-to 10cm (4”) diameter
When secondary forming factors are
included in the analysis, LWD assists the formation and maintenance of 40% of
all pools surveyed.
Pools formed
in association with LWD are frequently deeper with slower velocities
LWD retains
and sorts spawning gravels
LWD provides
habitat and nutrients for macroinvertebrates and microorganisms
Pools with LWD
can support more fish than pools without due, primarily, to increased cover
Pools with LWD are often support a
greater number of species
All sites with “N” prefix are LWD accumulations of natural origin
All sites with a “K” prefix were constructed in late-July and
early-August 2004
Site “N4”, the only channel-spanning jam, accounted for 60%
of the adult Chinook observed
Surveyed reach (from K1 to N4) is 1650’ long
Underwater video of adult spring Chinook
salmon holding in a LWD cluster several days after it was constructed
(Klickitat River Meadows Project, Site K1, Yakama Nation Fisheries Program
Underwater
video of a different adult spring Chinook salmon holding in a LWD cluster several days after it was constructed (Klickitat
River Meadows Project, Site K1, Yakama
Nation Fisheries Program)
Underwater
video of 3 adult spring Chinook salmon holding in a LWD cluster of natural origin
(within Klickitat River Meadows Project, Site
N1, Yakama Nation Fisheries Program)
Photo is of a channel-spanning log on
the EF Hood River.
This type of
position increases risk to boaters.
However, there was a sizeable pool
upstream pool and plenty of space to portage on the right bank which 9 of 10
boaters did without much trouble.
On this particular trip, one of the
less-experienced members missed the eddy upstream and ended up flipping on the
log and washed underneath.
He and his boat were recovered unharmed.
Boaters need to be constantly aware of their
environment.
Everyone should boat “Heads-up” – be conscious of
what’s downstream, boat spacing, and
available eddy space
Note river-wide log at top of photo and boats being portaged
Though this piece prevents running the rapid top-to-bottom, it is more of a
nuisance than a hazard (there is a good pool above it and ample opportunity to
scout)
The habitat value of its present position is negligible, but the
potential for this piece to serve a downstream ecological function is largely
dependent on remaining intact
Nearly channel spanning contributes to
greater hazard with a high flip potential at pictured flows
This
particular log can be passed on river-right, but the boater wasn’t paying
close enough attention as they approached
This is an ephemeral/temporary
resting location and the log will wash out of pictured position
Here LWD combined with boulders create a
convenient eddy in an otherwise busy/continuous reach
These areas are useful to boaters for resting, rescue, and recovery
Overall this run is fairly devoid of in-channel LWD
Much of it has to do with recruitment potential…where standing trees of
sufficient size exist (not uncommon), they generally fall from such a
height/distance that the trees break and the resulting pieces are easily
transported (i.e. less likely to hang-up in the main channel)
In this
case, LWD has been strained-out by riparian trees at the downstream end of a
bar and high-flow channel
The diagonal log interferes with approach
to the meat of the drop, but not a deal-breaker
Looks worse than it is though, and was easily passed to the right.
Note person (inside oval) for scale
Undercuts tend to pose more of a hazard
on most California rivers than LWD, however, there is always the potential for
strainers
In this case, a substantial log has been pinned in an undercut
sufficiently long (at least 10 years according to my source) for the rapid to
be named after it
A friend of mine front-surfing one of the
most dependable surf-waves on the Stabler to High Bridge section (“the Upper”)
of the Wind River
The hydraulic is created by the interaction of the log
and boulders in the bed of the river
Result of an
intense summer thunderstorm on a burned tributary watershed (Lake Creek) of the Middle Fork Salmon River (ID) in 2006.
The
resulting debris flow generated a debris fan that temporarily dammed the MF. A
LWD jam formed downstream at Pistol Creek
rapid.
The fan and channel braiding
immediately downstream continue pose a navigation challenge to boaters
Photos
were taken prior to blasting by the Forest Service to clear the jam from the rapid in July 2006
The
MF Salmon River is designated “Wild and Scenic” and occurs with the Frank Church – River of No Return Wilderness Area
The individual
who made the post has made numerous anti-wood-in-streams posts over the past couple of years.
Ironically, the poster zealously defended environmental
extremist Dave Foreman (co-founder of “Earth
First”) in a different thread
Sadly, he is apparently unaware of his own
hypocrisy
My job generally involves putting LWD into streams, so I am no expert on
removal.
Since half (3 out of 6) of the questions I received in advance involved
removal of wood, I contacted some colleagues at various jurisdictional
agencies.
The following content is based largely on their responses.
Characterizing something as a safety risk make us feel better about
removing it
•even
if removal may not be the appropriate prescription
•often
a way to cover-up laziness (i.e. not wanting to portage)
Rivers are not inter-state highways
This channel-spanning log on the Wind
River (~1/2 mi downstream of Stabler) was easy to float over at moderate flows
and a straightforward drag/portage on river-left at lower flows
There are
several class IV+ rapids downstream that would be far worse places to have to
deal with these logs.
Wind River (Washington) - February 2006
Surf wave created by LWD