Call for input on Collawash River map

Use this forum to report and discuss trails in need of maintenance. This will help organizations like TKO and agencies like the Forest Service get the most recent on-the-ground trail conditions.
raven
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Re: Call for input on Collawash River map

Post by raven » November 5th, 2014, 10:26 am

Koda wrote:
kepPNW wrote:Not sure that photo supports a higher average sedimentation load, any more than it suggests a nearby and recent point event. Especially given the crazy weather that week.
I agree, how is the annual sediment in the Collawash any different than it would be if no forest roads had been built? Are 'that many' tertiary forest roads that cross streams washing out annually each winter?
I think you are making an incorrect assumption about the main source of sediment. Road beds are cut into hillsides destabilizing them, much as trails do when cut into hillsides -- as per the photo. Water running under washes sediment out of the road base. Slides occur. Trees and associated fungi do not take root stabilizing the slope (and the road bed). Roads crossing streams -- not much of a problem. Streams crossing roads in heavy rains -- bigger problem.

raven
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Re: Call for input on Collawash River map

Post by raven » November 5th, 2014, 10:34 am

Koda wrote:If I understand this correct, essentially a Spotted Owl would have to fly miles (length of forest road) out of his way to avoid crossing the open airspace (lacking canopy for cover) of a forest road in order to avoid being hunted by the Barred owl or other predators. Since the Spotted Owl doesn't understand this, his numbers decline because he either instinctively does not cross any open airspace and thus overcrowds his current habitat or he does cross and gets predated at higher numbers along stretched of forest spur roads.... ?
Your understanding differs from mine. My take is that a barred owl uses the road to hunt, and attacks spotted owls it deems hunting in its preserve. I've seen barred owls using corridors to hunt -- at a place in SW Portland I frequent. So roads allow the barred owls to gain territory, not the spotted owls to reject territory.

greenjello85
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Re: Call for input on Collawash River map

Post by greenjello85 » November 5th, 2014, 1:43 pm

Koda wrote:If I understand this correct, essentially a Spotted Owl would have to fly miles (length of forest road) out of his way to avoid crossing the open airspace (lacking canopy for cover) of a forest road in order to avoid being hunted by the Barred owl or other predators. Since the Spotted Owl doesn't understand this, his numbers decline because he either instinctively does not cross any open airspace and thus overcrowds his current habitat or he does cross and gets predated at higher numbers along stretched of forest spur roads.... ?
Something tells me there isn't going to be an easy solution.

I’m still curious to alternate road management systems I previously mentioned (on page 4 )other than just simply decommissioning them.
I tend to fall on the maintain access side of this debate in general but from what I understand from reading the FS report on this area, a lot of the additional sediment attributed to roads is due to increased stream flow rates during flood events in addition to the more apparent wash outs/landslides from roads cut into steep hillsides. The roads/ditches act like an additional stream bed funneling snowmelt/rainwater into the natural streams much quicker than it would normally reach them, causing an increase in the severity of the flood event resulting in streams picking up much more sediment than they would have without the additional water. If it wasn't for this angle to the sediment problem, it might make more sense to only physically decommission roads that are known to have constant wash outs or slides and simply abandon those that are on more moderate slopes. Good conversations going on!

I understand the reasoning behind decommissioning the unused spur roads but I would still like to see the road going to whetstone maintained. I hike that trail a half dozen times a year and would be sad to hike an extra mile and a half on an abandoned road:) One road that is three-quarters of a mile that doesn't see much erosion seems like a good compromise. I think it is probably the highest use road(at least for hiking) on that map.

mcds
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Re: Call for input on Collawash River map

Post by mcds » November 5th, 2014, 2:04 pm

raven wrote: The picture (posted by mkrochta) shows an apples-to-apples comparison of runoff.
The turbidity of a river at a given location is the average of the turbidities of the upstream watershed. To the extent Collawash and Clackamas are not equal in this regard, the photo is a comparison of apples and oranges.

Suppose they are unequal. Suppose the Collawash is the 6 tributary to the Clackamas. Suppose the 5 upstreams have turbidities of 1,1,4,7,9 on that day. The average would be 4.4. If the Collawash was 8 on that day, then at it would appear more turbid than the Clackamas does at their confluence, even though it is not the highest contributor.
raven wrote:When sedimentation rates increase, the Collawash has the higher load.
One data point (the photo) cannot establish a relationship.

mcds
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Re: Call for input on Collawash River map

Post by mcds » November 5th, 2014, 2:22 pm

raven wrote:Three notes on fragmentation from my personal experiences.

(1) From casual observation of vegetation, cropping patterns seem to differ right beside trails and 100' or so off trail, implying trails impact animal feeding patterns.

(2) When I have compared mid-summer temperatures and humidities approaching clearcuts by bushwhacking (while maintaining a constant elevation) I've noticed drying and temperature effects starting at a quarter to an eighth of a mile from the edge of the clearcuts. Same notes when approaching roads, but the effects have been more localized, starting neare the roads than clearcuts. Anecdotal comment; no careful measurements done.

(3) Hiking along trail in the Adirondacks routed for a mile or so along a narrow jeep road partly covered by deciduous tree limbs, I passed a large great horned owl on one of the limbs. After I was 1-200 feet past it, it took flight along the road in my direction, its wings hitting branches and knocking some down, before it came to an opening large enough to climb out of the heavy forest or fly out over a lake. (I don't remember which.) The presence of the road opened hunting country for the owl that would have been inaccessible otherwise. I think the story is evidence of the potential impact on spotted owls of roads, since roads offer better hunting terrain for barred owls.
Good points. Tree limbs might be more prevalent along roads and at the edges of meadows, possibly forming walls that owls might or might not be able/willing to fly through, except at 'breaks', although spotted and barred owls have similar wingspans according to wikipedia.

mcds
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Re: Call for input on Collawash River map

Post by mcds » November 5th, 2014, 3:45 pm

raven wrote:Average sedimentation rates are determined by many individual events. At low flows little sediment is carried; at high flows stuff is knocked loose that would not be at lower flows. When a valley is stable, moderate to heavy rains will cause little sediment to be removed. When a valley is destabilized by logging or roads or fires, it does not take much.

The trail photo illustrates the destabilizing effects of trails. Roads are worse.

So yes, a point event. That's the point.
I agree and disagree. In addition to my previous post, another basic point is that the photo posted by mkrochta does not in any way, to my eyes, indicate the source within the watershed of the sediment. Mkrochta's photo shows only the total sediment level from the entire watershed.

The photo posted by mkrochta could reflect ...

a) sediment due to a single catastrophic event somewhere in the Collawash watershed. That event may or may not have been caused by or have involved a red or black road on the current version of the Bark map.

b) sediment due to general road erosion widely distributed over the watershed (due to saturated/frozen terrain due to weather conditions)

c) sediment due to naturally or unnaturally unstable stream banks in the watershed triggered by the weather that produce flood-stage river flows

d) sediment due to distributed erosion on previously logged slopes in the watershed that have not fully recovered

e) .....

It's probably due to a bit of all of #b-e and possibly one or more #a's. But the take home of #a-e is that 1) the sediment in mkrochta's photo is not necessarily due to roads, and 2) the sediment in mkrochta's photo may be due to a catastrophic event or due to distributed erosion.

Assuming the road density in the upstream watershed of the Clackamas is similar to the road density in the Collawash watershed, then mkrochta's photo shows that forest roads don't necessarily destabilize the terrain to a critical extent. It could be that the road contractor for the Collawash goofed, or skimped. Or it could be the Collawash roads were built in a different year under different best-practices. Or ....

If the sediment was due in large part to a catastrophic, how frequent are similar events? Was it a 100-year event? 50-year? ... The week of foul weather also correlated with the rockslide that closed I84. How often does that happen? Was the rockslide a 100-year event?

Regardless of the source of the Collawash sediment, the severity of the foul weather suggests that Collawash sediment levels do not frequently reach the level seen in mkrochta's photo. Maybe only once every few decades. On all other days, and throughout most years, the difference in sediment between the Collawash and the Clackamas my be imperceptible to the eye.

The next time that a similar foul weather week occurs, the catastrophic failure may occur in the Clackamas watershed up stream of the Riverford Campground area (where mkrochta's photo was taken) ... and all the conclusions will be reversed.

Mkrochta's photo may be severely misleading, just as a photo of the I84 rockslide could lead to a severely misled generalization. I am not saying mkrochta's photo is misleading, but the coincidence with the extreme weather lead-up makes it likely, in my opinion.

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Koda
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Re: Call for input on Collawash River map

Post by Koda » November 5th, 2014, 3:57 pm

Its worth noting here that a very large portion of the Collawash watershed is located within the BOW Wilderness area, which does not contain roads or clearcuts.
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greenjello85
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Re: Call for input on Collawash River map

Post by greenjello85 » November 5th, 2014, 3:59 pm

The photo itself doesnt demonstrate consistently high turbidity levels but page 3-19 of the earlier noted fs report, there is a section "sediment and water quality" states sediment levels in the collawash and lower bagby are consistently higher than the Clackamas due to artificially increased flows and naturally unstable slopes established by turbidity readings and observations.

mcds
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Re: Call for input on Collawash River map

Post by mcds » November 5th, 2014, 4:19 pm

Koda wrote:Its worth noting here that a very large portion of the Collawash watershed is located within the BOW Wilderness area, which does not contain roads or clearcuts.
Good point. Has there ever been logging in the BOW Wilderness portion of the Collawash watershed? that is, are there any old roads in that area?

Of course, the suspected point event (catastrophic event) nonetheless may have happened in BOW Wilderness, and perhaps more likely.

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Koda
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Re: Call for input on Collawash River map

Post by Koda » November 5th, 2014, 4:26 pm

mcds wrote:
Koda wrote:Its worth noting here that a very large portion of the Collawash watershed is located within the BOW Wilderness area, which does not contain roads or clearcuts.
Good point. Has there ever been logging in the BOW Wilderness portion of the Collawash watershed? that is, are there any old roads in that area?

Of course, the suspected point event (catastrophic event) nonetheless may have happened in BOW Wilderness, and perhaps more likely.
lidar data shows no old road features in the BOW.

The only event within the BOW was the last forest fire.
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