[env-trinity] Information on Trinity and Lewiston Dam releases

tstokely at trinityalps.net tstokely at trinityalps.net
Tue Jan 3 11:06:09 PST 2006

Dear Env-Trinity subscribers,

I have had some inquiries about dam operations by downriver concerned
homeowners and others.  Since I don't operate the dams, I thought I would
let you know who does and how to contact them for information during the
big storms!

Lewiston Dam releases are still 1500 cfs.

You can get put onto an automatic phone notification list by calling the
Bureau of Reclamation at 530-275-1554 and ask to be connected to the
operations person who has the automated phone notification list. 

There is also a recorded message of river releases at 530-246-7594.
You can find Trinity Lake storage at the website
<http://cdec.water.ca.gov/queryDaily.html> and enter the station cle (it
stands for Clair Engle, the former name of Trinity Lake).

The Bureau of Reclamation’s Safety of Dams criteria calls for certain
target storage below in Trinity Lake.  If storage is above the target, it’s
likely they will release extra water to make room for the high inflow from
storms.  Depending on the snowpack, intensity of storms and expected
runoff, they will release the amount of water necessary to keep Trinity Dam
from overtopping.  

The maximum “controlled release” from Trinity Dam is 13,750 cfs.  The
maximum “uncontrolled release” is estimated at 30,000 cfs (Lewiston Dam can
also release about 30,000 cfs).  The controlled releases are from outlets
within Trinity Dam. Uncontrolled releases are when water reaches the “glory
hole” spillway at 2370’ elevation and water is released uncontrolled into
Lewiston Reservoir.  

Of course, tributary inflows have a lot to do with how large flows are
downstream of Lewiston Dam.

About 3,000 cfs can be diverted to the Sacramento River from Trinity Dam
through the Clear Creek Tunnel before it gets to Lewiston Dam, but when
there are big floods along the Sacramento River, that is not always


Nov 1- Dec 31            1,850,000 AF (2331’ elevation)

Jan 1-Jan 31               1,900,000 AF (2334’ elevation)

Feb 1-Feb 28,29          2,000,000 AF (2341’ elevation)

March 1-31                  2,100,000 AF (2348’ elevation) 

Happy New Year!

Tom Stokely
Principal Planner
Trinity Co. Planning/Natural Resources
PO Box 2819
190 Glen Rd.
Weaverville, CA 96093-2819
530-623-1351, ext. 3407
FAX 623-1353
tstokely at trinityalps.net or tstokely at trinitycounty.org

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