WSP10769

• File Number: 8220.105
• Description: Colorado River-Water Projects-Navajo
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 7/1/2001
• Author: BOR
• Title: Revised Draft Environmental Assessment for the Jicarilla Apache Nation Water Subcontract-aka USBR/PNM Water Contract Renewal and Extension
• Water Supply Pro - Doc Type: Report/Study

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continues as long as the four electrical generation units ofSJGS are in operation and using coal from San
Juan Coal Company (SJCC) as their fuel source.

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As a result of these two contracts, the combined total water currently available for consumptive use by
SJGS is 24,200 AF per year. Although SJGS has not required the total 24,200 AF available so far, it has
ust:ci most or aii or lnt: i 6,200 ,U111 U(1 I Ai- vi USSR .W.Z":CI 0-\'-~1 ih~ Ja5i 1 G Y~aj"':; (Tabk 1). '.'lith ~~:ie~t
and rising capacity factors shown in Table I. PNM expects to require, at a minimum, all of the water from
the Jicarilla Apache Nation Water Subcontract as well as BHP water.

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The majority of the water consumed by SJGS is used for cooling purposes. Cooling is essentially
accomplished through the evaporation of the water. Consequently, consumption of water is closely
related to the generation of electrical power; i.e., the more electrical power generated. the more water is
consumed.

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In addition to the water pumped by PNM for use at SJGS, PNM also diverts water for the BHP-owned
coal mine under BHP's separate water permit. This is not part of PNM's 24.200 AF. This arrangement is
part ofthc fuel supply agreement benveen PNM and BHP.

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5.1 Current Operation of Diversion aud Pump Station

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The SJGS weir is a broad concrete structure that extends from shore to shore across the river (Figure 3).
During high water flow in the river (over 8,000 cubic feet per second [cfs]) there is bypass flow around
the south side of the weir. Water has been diverted for use at SJGS continuously since 1973.

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The weir is 3.5 feet high in thc middle where water is spilled into a stilling basin created by a concrete
apron between the weir and a I-ft. retaining wall 32 feet downstream (Figure 4). The stilling basin is the
width of the river. The presence of the basin results in a maximum 2.5 feet that must bc ascended in order
for fish to go over the weir. As flows increase, the difference in water levels is reduced. For example,
with flows of approximately 1.000 cfs the depth of the basin is 2 feet, reducing the height difference to
1.5 feet. Although higher flows reduce the height difference, the water velocity also increases. The weir
provides an unquantified impediment to upstream fish movement. Studies conducted as part of the
SJRRIP have shown that some fish are able to move upstream past the weir but their specific method of
movement is not known and the number of fish dissuaded from upstream movement by the presence of
the weir is not known. There is also a sluice tunnel 4 feet by 6 feet in the weir on the north side of river.
This tunnel is used to sluice the inlet structure of sediment. Normal operation is to have the sluice gate
open 8 to 12 inches.

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Trash screens and isolation gates are located at the point of diversion. A concrete channel approximately
490 feet long delivers diverted river water to the pump house or returns it to the river. Water to be used
by SJGS moves from the concrete channel through traveling nonimpingement screens to three pumps
capable in combination of pumping a maximum of 17,000 gallons per minute (37 cfs) to a 11 O-acre
storage reservoir. From the storage reservoir, the water is pumped to SJGS. A polymer storage and feed
system is located at the river pumping station to feed a high molecular weight polymer to the pump
discharge line (to the raw water reservoir). Addition of the polymer to the water improves settling of
suspended solids in the reservoir and is used only during periods of high river turbidity. No polymer
reaches the San Juan River.

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