[env-trinity] Trinity River flows are near record

[Josh Allen]

Trinity River flows are near record 

 

Trinity Journal

May 24, 2006

150th Year, No. 21

 

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A huge volume of water gushes from the glory hole's raceway outlet
(upper right). The buildings are the dam's hydroelectric plant. 

 

By AMY GITTELSOHN
The Trinity River is roaring with a release from the Lewiston Dam of
10,000 cubic feet per second - the highest it's been since 1974.
Predicting the release to the river has been a moving target over the
past few weeks as Central Valley Project operators have released higher
flows than anticipated to compensate for rapid inflows to Trinity Lake
from a heavy snowpack.
"It's a pretty dramatic sight," said Doug Schleusner, executive director
of the Trinity River Restoration Program. "We will be at 10,000 at least
through the end of the week, and we're currently looking to see if we
can go to 11,000."
On Tuesday, Schleusner said that decision would be based on monitoring
being performed that day, and if the release does go to 11,000 cfs it
would probably be for only one day.
The higher flows are meant to improve habitat for fish and this year are
also serving the purpose of keeping the reservoir at a level operators
are comfortable with.
"These (extremely wet) years don't come along often and we would like to
take full advantage," Schleusner said, but "we'll only do that if we're
totally convinced that we could do so safely."
The 10,000 cfs is the second-highest release to the Trinity River on
record since the dam has been in place. The highest release was made in
January 1974, when the release was raised to 14,400 cfs during
destructive storms.
Although a plan to restore the Trinity River calls for a spring peak
release of 11,000 cfs in an extremely wet year such as this one,
restoration program managers had not expected to be able to do that for
fear of damaging structures. The federal Bureau of Reclamation had
approved a proposal by the Trinity Management Council calling for a
spring high of 8,500 cfs, with increases above that allowed if it could
be done safely.
With the recent dry spell, the tributaries to the Trinity River subsided
enough for the higher flows to be possible, Schleusner said.
The schedule had called for a spring peak lasting 13 days, but that time
period will be shortened to compensate for the higher flow.
Researchers with the restoration program are busy monitoring sediment
movement and staking out high water areas.
"We will use this new release level now to calibrate all the models we
use to make a prediction," Schleusner said.
On Tuesday, water was pouring out of Trinity Lake not only through the
power plant and outlet works at the dam but also through the "glory
hole" drain located above the dam.
The water began trickling into the glory hole last Friday afternoon and
increased over the weekend.
Schleusner was quick to say that this is not an uncontrolled spill,
adding that whatever goes through the glory hole can be compensated for
by adjusting the gates at the dam.
The flow to Clear Creek Tunnel, which takes water from Lewiston Lake to
Whiskeytown Lake and the Sacramento River, can also be adjusted, he
said.
He added that teams have met with property owners along the river, and
"most of them that we've talked to we've worked with them consistently
enough that this is not a surprise."
With high releases, river restoration personnel are monitoring the river
in case of problems, Schleusner said.
"Certainly," he said, "the public is encouraged to talk to them or the
office with questions or concerns." 

 

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