[env-trinity] Trinity Journal 11 11 09

Byron Leydecker bwl3 at comcast.net
Wed Nov 11 14:19:45 PST 2009

Diversion factor 
More water flows east than into Trinity River 


PHIL NELSON THE TRINITY JOURNAL A boat ramp at Trinity Center falls far
short of a lowered Trinity Lake. 

More Trinity River water was diverted for Central Valley Project use than
sent down the river in the last water year. 

Preliminary figures from the Trinity River Restoration Program indicate that
456,641 acre-feet of water was released from Lewiston Dam to the Trinity
River during the 2009 water year which ended in September, while 539,172
acre-feet was diverted via underground tunnel to Whiskeytown Lake and the
Sacramento River. 

It was a dry year, and inflow to Trinity Lake was approximately 800,000
acre-feet, so the lake was drawn down substantially. 

The split weighted toward diversion goes against former Interior Secretary
Bruce Babbitt's Trinity River Record of Decision which calls for the river
to get the greater proportion of water during a dry year, said Tom Stokely,
retired Trinity County senior resource planner and a board member of the
California Water Impact Network. 

In a dry year, the Record of Decision calls for a minimum Trinity River
allocation of 452,600 acre-feet and an average Central Valley diversion of
358,400 acre-feet. 


The Trinity River flows toward the north end of Trinity Lake between Trinity
Center and Coffee Creek. The lake was drawn down significantly this past
year, with nearly 1 million acre-feet released . 

Regarding last year's much higher diversion, Stokely said, "They're not
supposed to under the Record of Decision but there's no one or no
controlling authority to tell them to change their ways unless the interior
secretary himself intervened to tell them to do so, or someone filed a
lawsuit to tell them they weren't in compliance." 

The Trinity River Restoration Program's executive director, Mike Hamman,

Hamman is a federal Bureau of Reclamation employee, but the program he heads
serves many agencies involved with river restoration. He said the Record of
Decision sets firm volumes for water down the river depending on water-year
type - and that volume was met - but the amount diverted for agriculture can
be tweaked for operational purposes. 

"The Central Valley office makes that call," he said. "There aren't any hard
and fast rules except for the fishery flow." 

Furthermore, although it sounds counterintuitive, Hamman said the additional
water was sent through the tunnels in order to aid Trinity River fish. 

He explained that a large block of water was diverted due to what is
essentially a temperature and plumbing issue: During summer, release to the
Trinity River is to be 450 cubic feet per second. With the lake low, in the
heat of summer CVP managers must send approximately three times that volume
through Lewiston Lake to keep the water cool enough for fish on the other
end. Sometimes even that doesn't do the trick and they use Trinity Lake's
lower, auxiliary outlet to get the lower, cold water. However, the lower
outlet was not originally intended for temperature control and was built to
be fully open releasing about 1,800 cfs or fully closed. Otherwise, valve
damage could result. 

Operators have also tried pulsed flows through the lower outlet as one way
to use it without releasing as much water, Hamman said. 

In another issue, water through the lower outlet does not go through the
power plant at Trinity Dam, which affects power users, including the Trinity
Public Utilities District. 

Bureau of Reclamation Area Manager Brian Person noted that over time, the
water split has been what was called for in the Record of Decision - a 53
percent diversion and 47 percent down the river. 

He noted that in an extremely wet year much more water is available for
diversion, but "would that happen that year? Probably not because you might
want to store some of that." 

>From the California Water Impact Network, Stokely does not think enough
water has been stored in good water years in Trinity Lake. 

Keeping the lake higher would mean more cool water available for fish
without sending such large amounts through the system that some must be
diverted, he said. 

"It's pretty obvious if the reservoir gets too low there won't be cold water
available to keep spawning fish and incubating eggs in the gravel alive," he

"It's a very unfortunate plumbing circumstance that they have to send three
times more water down the hill to keep the Trinity cold," Stokely added.
"They need to have a physical solution to that and they also shouldn't send
so much over the hill in the wetter years." 

In addition to storing more in the lake during wet years, Stokely suggested
other solutions could be to put a pipeline around Lewiston Lake to deliver
cold water to the river or tear down Lewiston Dam and pump water into the
diversion tunnel, providing seven more miles of fish habitat. 

>From the restoration program, Hamman said it is too early to determine what
kind of water year this will be, although the National Weather Service
prediction for the next few months is for a 70 percent chance of normal or
above normal precipitation. 

If it is another dry year, he said, "we will be challenged as far as the
temperatures go." 

Byron Leydecker, JcT

Chair, Friends of Trinity River

PO Box 2327

Mill Valley, CA 94942-2327

415 383 4810 land

415 519 4810 cell

 <mailto:bwl3 at comcast.net> bwl3 at comcast.net

 <mailto:bleydecker at stanfordalumni.org> bleydecker at stanfordalumni.org

 <http://fotr.org/> http://www.fotr.org 




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