WSP04803

• File Number: 8221.110.A
• Description: Juniper-Cross Mountain Project
• State: CO
• Basin: Yampa/White
• Date: 10/1/1980
• Title: Summary Report: Juniper-Cross Mountain
• Water Supply Pro - Doc Type: Project Overview

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PROJECT DESCRIPTION. Juniper-Cross Mountain Hydro'
electnc project IS a proposed two dam and reservoir project west
of Craig on the Yampa River in Northwest Colorado. It will
produce350 million kilowatt hours of electricity annually, store
1.2 million acre.feet of water, accommodate 500,000 recreation
days per year and has the potential to irrigate 14,000 net acres
directly and more by exchange. Juniper Dam will have a min-
imum release of 25 cfs and the capability of going to maximum
discharge of 7,000 cfs instantaneously. The seven-river-mile stretch
between Juniper Dam and the upper end of Cross Mountain
Reservoir will be a part oJ the project and will be subject to
fluctuations. Cross Mountain Dam will serve essentially to re-
regulate Juniper peaks: maximum discharge of Cross Mountain
is 3,000 cfs ~nd discha~ge is limi.ted to increasing no more than
45 percent In a 30-mlnute pertod. A new 345-kilovolt line
from the Juniper and Cross Mountain pow'er plants to Craig
will be located parallel to an existing right of way for a federal
138-kilovolt I ine except for the sh art con~ections to each power
plant. A portIOn of the Juniper reservoir basin contains coal
deposits. All federal coal in close proximity to the Yampa River
has been determined by the Bureau of Land Management to
be unsuitable for coal leasing. Of the privately owned coal in
the basin, inundation is not considered a significant factor in
determining whether those deposits are mined or not.

Juniper Dam and Reservoir
Juniper Dam will be a 220-foot earth and rockfill structure
with a central impervious core and chute type spillway on the
right abutment and low level outlets in a converted diversion
tunnel through the right abutment. Maximum plant discharge is
7,000 cfs;' low level outlet capacity totals 1,800 cfs through two
Howell-Bunger valves. Reservoir level is a maximum elevation of
6125 feet with a total capacity of 1,083,000 acre-feet of water of
which 692,000 acre-feet is active storage. The balance or dead
storage will hold 350 years of river sediment eliminatin'g siltation
as a problem and keeping the downstream Cross Mountain Dam
essentially free of silt. Juniper Dam will be located near Maybell,
approximately 25 miles southwest of Craig. The basin is con-
sidered excellent with regard to seepage; average annual evapor-
ation IS projected at 43,800 acre-feet. Elevation of Juniper was
selected to avoid impacting coal mining activity in the area. The
Juniper spillway is 120 feet long with three 35-by-35-foot radial
gates that have a capacity of 134,900 cfs. Across a 28-year study
period maximum fluctuation was 65 feet - from 6125 to 6060'
average annual fluctuation would range from 6125 to 6090. '

Cross Mountain Dam and Reservoir
Cross Mountain Dam, located 58 miles west of Craig near the
downstream end of Cross Mountain Canyon will be a 260-foot
high concrete arch structure with 208,000 acre-foot capacity of
which 115,000 acre-feet will be active storage. Cross Dam will
have a central overflow spillway 176 feet long with six 20-by-20-
foot gates. Peak outflow is 96,000 cfs while the river has had a
maximum historic flow of around 20,000 cfs. Maximum elevation
of Cross Mountain Dam was selected to avoid raising the water
table in Maybell and inundating the graveyard. Cross Mountain
Reservoir will lose 19,700 acre-feet of water to evaporation annu-
ally. Cross Mountain, across a 28-year study period, sh'owed a
maximum fluctuation of 18 feet from 5888 to 5870; average

SUMMARY
REPOR T

October, 1980
Subject to Revision

annual fluctuation would range from 5887 to 5880. The basin
is considered excellent with regard to seepage; sediment is not a
factor.

IRRIGATION. Juniper-Cross Mountain will affect Northwest
Colorado agriculture in four different ways: the project will
inundate 4,000 acres of existing irrigated lands; it provides the
potential.Jor irrigating 18,000 acres of new lands plus additional
acreage by exchange; it can provide much needed supplemental
water to irrigated lands that run short late in the season and it
can generally ease competing water supply demand. The water
supply of Juniper-Cross Mountain will generally ease the pressure
on agriculture brought about by increasing demand for water by
municipal and industrial users, particularly as that demand relates
to energy development. With the potential for a net increase in
irrigated acreage of at least 14,000 acres, the total possible value
of new irrigated lands from the Juniper-Cross project to the
regional economy is $12.9 million annually.

FLOOD CONTROL. Though Juniper-Cross Mountain was not
designed as a flood control project, it will be filling during the
season of high runoff and flood. To some extent, it will reduce
the severity and frequency of floods on the Yampa and Green
Rivers downstream of the project.

RECREATION. State and federal studies plus a 1980 Moffat
County survey have all identified shortages of recreational facili-
ties in Northwest Colorado for several activities including water
skiing, fast power boating, camping in campgrounds, picnicking in
established areas, ice skating on lakes and streams, lake and reser-
voir cold water fisheries and swimming. The Juniper-cross Moun.
tain construction budget includes $1,250,000 for recreational
features that would be phased in on the basis of need and use
and would be contingent on an appropriate local state or fed-
eral agency managing the project's recreation sy;tem. Though
the entire recreation plan totals $4.5 million, the difference
is anticipated in future government grants.
Initially, one campground with 65 sites each will be con-
structed at Juniper and Cross Mountain. Each will be capable of
expansion to 150 or more sites and if that eventually proves in-
sufficient based on actual demand, another campground can be
constructed at Cross Mountain. Four picnic areas totaling 100
tables will be constructed initially with plans for an ultimate
total of six areas and 265 tables. Each reservoir will have one
major boat landing,one boat ramp and a 50-boat marina. While
fees for all other recreational uses will be determined by the man-
aging g?ver~mental agency, the marinas will be operated by a
conceSSIOnaire and the fees for the marina will be based on
negotiations with the River District.
The main body of both reservoirs will be available for high-
speed boating. Cross Mountain Canyon and Juniper above Signal

* cfs or cubic feet per second is the basic measurement of
flowing water. One cfs or 7.48 s:a1lons per second is 646,317
gallons per day or just a little less than two acre-feet. An-acre
foot is the basic measurement of standing water - one foot
on an acre or 325,851 gallons.