[Fosc] Some thoughts on the Trout Kill
christopher at formulate.com
Fri Feb 8 10:19:32 PST 2008
Hi Mark -
"wind throw" as the cause of the Oak's demise is highly unlikely for
a number of reasons which I will detail below.
A I stated in my email of a few days before the loss of the Oak, the
Park Blvd drain had overflowed into the San Luis glade and was
running down the trail and diving down into the canyon right at the
base of this Oak. It had cut a 3 ft gully at the base of the tree and
underneath the oak, exposing it's root ball. You can still see this
gully now. The volume of the water was incredible, coverting the
trail to a rushing creek with many inches of rapidly flowing water.
This same water super-saturated the soil around and below the Oak to
such an extent that it triggered the landslide immediately downslope
of the Oak which I also reported. I immediately took steps to
redivert the storm water, but clearly not before the damage was done.
I was home the evening when the Oak fell and went outside immediately
after. The wind was gusting strongly in the canyon - but not
significantly more than your standard storm blow we experience 5-10
times a year. This Oak has weathered far greater storms in it's
lifetime. The wind was gusting into the canyon the from NW. The
removed acacias were down canyon from the Oak and to the SW, or
perpendicular to the direction of the wind. Had they still been
there, they would not have provided wind shelter to the Oak. If the
Oak had been blown over from that direction, it would have fallen
upslope, not downslope as it did.
The fatal blow was that the Oak's roots were sitting in
supersaturated "mud". Had the wind really been strong enough to down
an Oak, we would have seen a lot of other devastation in the area -
downed limbs, signs down, etc. There was no other damage anywhere.
The wind was just enough to give the tree a push - the wet soil was
the real culprit.
Finally - the removed Acacia's were relative newcomers to this area.
I haven't checked the rings, but I'd be surprised if they were even
20 years old. To suggest that these young Acacia's were protecting an
Oak that had probably been in place 100 years or more seems unlikely
in the extreme. The primary reason we (I) lobbied to remove the
Acacias is that they were slowly killing four surrounding other Oaks
(not the one that fell) and they were also threatening to fall as
well. Had these Acacias been allowed to fall, they would have most
definitely caused much damage to the surrounding Oaks.
I'd be happy to show you (or anyone else for that matter) around and
point out the particulars of this event that I reference in this
What we have here is another example of the chronic point source
stormwater drainage issue in the watershed. This time it lead
directly to the tragic loss of our beloved Oak tree. I hope we can
make significant inroads in the coming years to address both the
stormwater dumping into the canyon as well as the other sewage and
dumping issues referenced by this thread.
At 11:42 AM -0500 2/8/08, Mjrauz at aol.com wrote:
>First of all, had Kathren Stevenson, our Restoration Director, not
>looked into El Centro pool, we would not have known of this fish
>kill. Many thanks to Kathren's alertness and the City's
>responsiveness. This underscores the value of FOSC. We add immense
>value to the watershed.
>The kill was evidently caused by a dumping of a painting solvent
>into the gutter on Oakmore Ave. that drains into a side tributary at
>the turnaround area. The fumes were noxious on the trail and worse
>at the drain. Craig Pons of the City collected some white liquid for
>analysis and Kathren collected a fish for EPA tissue analysis.
>It is of interest to note that 11 trout died in the stretch of creek
>from the turnaround area downstream to some point. The floaters
>drifted down and fell into the El Centro Pool and sank. No trout
>were seen downstream by me of this point. So that (was) a pretty
>healthy population in a small stretch of restored streambank. While
>I was there, so was a Great Blue Heron perched in the alders above
>the kill site probably looking for easy pickings. I hope a toxic
>food chain doesn't develop.
>The heron had easy access because of the downed trees at Benevides.
>The Tree Service finished cutting up the Benevides oak branches, and
>took it all down to the stumps, so the tree cannot resproat from any
>branches. (I'll refrain from any further comment about this).
>It occurred to me however, that the fallen oak have have been a
>victim of wind throw. The previous removal of tall acacias were
>taken down and the next big storm with high winds toppled the oak.
>The forest structure changed and may have exposed the oak to more
>wind and with wet earth, it fell. We must consider our role in its
>demise. And the hard-learned lesson here may be the value of alien
>This area is across from the fish kill and looks like FOSC has work
>to do to repair the areas. If we don't, then nobody will. And again
>that is the immense value of FOSC and I wonder how many outside of
>this list really appreciate this fact. "We all live downstream."
>Mark J. Rauzon
>Friends of Sausal Creek-Board President
>4701 Edgewood Ave.
>Oakland, CA 94602
>mjrauz at aol.com
>Biggest Grammy Award surprises of all time on AOL Music.
>Fosc mailing list
>Fosc at lists.sausalcreek.org
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Fosc