WSP10800

• File Number: 8277.200.10
• Description: California's Central Valley Project
• State: CA
• Basin: Colorado Mainstem
• Date: 1/1/2000
• Title: Western Water -- Central Valley Project Improvement Act Update
• Water Supply Pro - Doc Type: Report/Study

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Historically, an average of 74 percent of the
Trinity River's flow has been diverted into
the Sacramento River to augment CVP
supplies. After nearly 14 years of study,
feder<ll officials rclt~ased a draft report in
October recommending that instream flow
in the Trinity be increased to an average of
595,000 acre-feet a year, 47 percent of river's
natural flow. Water diverted [It Lewisron
Dam flows through an II-mile wnnd into
\VhiskeYlOwn Reservoir, above, loc3tl,d 10
miles southwest of Shasw Dam.

Trinity River Flows
With completion of Trinity Dam and
the II-mile Clear Creek Tunnel 37
years ago, the Trinity River was linked
to the Sacramento River - with up to
90 percent of the Trinity's average
annual flow of 1.2 million acre-feet at
Lewiston Dam diverted to generate
power, irrigate crops and enhance
industrial development hundreds of
miles away.
The Trinity River Authorization
Act required minimum water releases
of 120,500 acre-feer to maintain
Trinity River salmon and steelhead
populations. From 1965-1997, an
avcrage of 988,000 acre-feer (74
percent) of the Trinityls flow was
diverted annually to the CVP, prima-
rily for use in the Sacrarnento Valley's
Tehama-Colusa service area and
Westlands Water District.
As farmland on the west side of
the San Joaquin Valley flourished,
Trinity River populations of steelhead
trout and coho and chinook salmon
declined. In 1981, Interior direcred
that instream flows be increased~ on
average, to 340,000 acre-feer per year.
In 1984, a 10-ycarfish restoration
effort was authorized by Congress.
Upon completion of rhe fish/flow

12

study, Interior was to decide if higher
instream flows and habitat improve~
ments were needed to boost historic
fish populations. The CVPIA directed
Interior to complete and implement
this study, if agreed upon by Interior
and the Hoopa Valley Tribe.
In Octobcr, after nearly 14 years
of study, federal officials released a
draft flow study and Environmenral
Impact Study/Report (EIS) recom-
mending that instream flow in the
Trinity be increased to an average of
595,000 acre-feet a year, 47 percent
of river's natural flow. (Instream flows
would range from 369,000 acre-feer
in critically dry years to 815,000 acre-
feet in wet years.) In addition to
boosting mstream flows, the EIS
recommends a number of habitat
restoration projects.
Fanners on the west side of the
Central Valley stand to lose the mosr
if Trinity River flows are boosted - an
average of 255,000 acre-feet a year.
They say that the water return threat-
ens them and the state with economic
collapse and that groundwater over-
draft in the San Joaquin Valley will
increase. They also argue that $96
million already has becn spenr on
fishery restoration programs without
any effcct and that there is no evi-
dence that increases in flows have or
will increase fish populations.
"Actions to improve the Trinity
River fishery cannot occur in a
vacuum/l Peltier wrote Babbitt in a
Nov. 9 letter. "The Trinity River
ecosystem and CVP operations and
Bay~Delta program are inextricably
linked."
Fishermen and environmentalists,
however, believe even more water is
necessary to restore salmon and
steelhead runs - they are pushing to
boost instream flows to 70 percenr of
the Trinity's natural flow. "PCFFA
based its recommendation on biologi;
cal science and the law, not political
scicncc,l' Grader wrote in a Jan. 19
letter to the USFWS. "The fish need
water. Yet even in the preferred
alternative Interior is offering the river
less than 50 percenr of its flow"

Western Water