Re: Rapid River TR
- From: "Bob Weinberger" <bobsstuff@xxxxxxxxxxxxxxxxxxx>
- Date: Fri, 06 Jul 2007 08:15:17 GMT
"Dave LaCourse" <dplacourse@xxxxxxxxxxxxx> wrote in message
news:l7sq83ll3kq62qmvtos40m4vhcbmiktfvt@xxxxxxxxxx
On Thu, 05 Jul 2007 18:27:52 -0400, Dave LaCourse
<dplacourse@xxxxxxxxxxxxx> wrote:
could not fish the river because of Biblical flood levels.
Dave
BTW in a great many instances, occasional extremely high flows can be very
therapeutic to river sections below a dam. On many rivers the moderation of
peaks and valleys in flow rates that many dams provide relative to undammed
conditions, can allow buildup of sediment in the stream below the dam and/or
prevent formation of historically normal features such as sand bars .
A local river that supports a fabulous Brown trout fishery (not unusual to
catch double digit # of trout/day averaging 17-22" on dries) illustrates
this quite well.. The reservoir behind the dam is huge(>60mi. long by up to
15 mi. wide), but it is strictly an irrigation reservoir - no power
generation. Between October and April the irrigation district historically
has maintained flows of from 10- 40 cfs and raised it to 200-300 cfs through
the irrigation season. Over the last ten or so years several insect
hatches, including the Skwala hatch for which the river was somewhat famous,
had all but disappeared due to sediment build up. As a result the quality of
the fishing was in decline.
Winter before last it became apparrent the the watershed above the reservoir
(larger than many Eastern states) was receiving a very heavy snow pack. So
about December the irrigation district increased flow from about 40 cfs to
600cfs and then in early spring increased flows to 1200cfs.. But that
wasn't even close to enough. By June flows were above 11000 cfs - over 40
times what they had been kept at during that time of year for decades - and
stayed at or near those levels for over a month..
Of course there were many in the flyfishing community that wailed that the
fishery had been ruined and would take decades to recover if it ever did.
And of course fishing was next to impossible during the extremely high
flows. However, here only a year later, fishing has been great, with
prolific hatches of species of mayflies that that we rarely saw or even
hadn't been seen in years (though the Skwala hatch was very sparse, but will
likely be good next year). People did need to change what they carried in
their fly boxes though (BFD), as there were less of the ones, such as
calibaetis, that thrive in sediment.
We need to remember that before the dams were there, the river likely
periodically experienced flows that were both considerably higher or
considerably lower than we are used to seeing post dam. The trout survived
those conditions (if there even was a trout fishery prior to the dam). So
before we assume the sky is falling we may want to do a little more
reasearch into historic flow conditions.
Bob Weinberger
.
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