WSP07510

• File Number: 8200.760
• Description: Yampa River General
• State: CO
• Basin: Yampa/White
• Water Division: 6
• Date: 1/1/1981
• Author: USGS
• Title: Assessments of Impacts of Proposed Coal-Resource and Related Economic Development on Water Resources - Yampa River Basin - Colorado and Wyoming - A Summary - 1981
• Water Supply Pro - Doc Type: Report/Study

For a wet-cooling tower system. the dissolved-
solids load in the river would decrease by an es-
timated 8.400 tons (7,620 t) per year. while the
dissolved-solids concentration would remain un-
changed at 140 mgfL (table 6). The land area oc-
cupied by the towers is conaiderably less than that
required for cooling ponds (N ational Academy of
Engineering, 1972, p. 131). The wet-cooling towers
may increase fog, ice, and precipitation over the
immediately surrounding area.
In dry-cooling towers, the cooling water moves
through 'I collection of finned tubes and the system
operates on the same principle as an automobile
radiator. Like an automobile radiator, the rate of
consumption of water is virtually zero, because
cooling occurs by conduction only (fig. 3D). Several
characteristics of dry cooling relative to wet cooling
are discussed by Hirsch, James, and Schefter
(1978).
Each cooling-system technology has its own ad-
vantages and disadvantages. For example, to avoid
withdrawing the vast amounts of water necessary
for once-through cooling, ponds that evaporate
substantially more water can be used. To prevent
the di8801ved-solids concentration of the river from
increasing when an evaporative system is used, the
long-term hazard of permanent impoundment of
the salts must be accepted. To achieve the advan-
tages of no water consumption at all, the increased
air pollution and waste of coal due to the decreased
efficiency of a powerplant with dry cooling must be
accepted.
Perhaps a useful comparison of water-use
implications for coal-use alternatives is to consider
inbasin conversion of an additional 12.5 million
tons (11.3 million t) of coal to electricity or syn-
thetic gas products or export of the same amount of
coal via a slurry pipeline. Comparisons of
withdrawals and consumption of water are made in
figure 4. The magnitude of water-use requirements
in electric-power-generation facilities can be noted.
All water exported in a slurry pipepine is a con-
sumptive loss from the standpoint of the basin;
however, some of this water can be recovered and
used at the delivery end of the pipeline.
Nonetheless, basin water 1088es using a slurry-
pipeline transport alternative are about one-fifth to
one-third as great as the losses for cooling purposes
in electric-power generation in the basin (fig. 4B).
The choice of coal use has a profound effect on
the amounts !lnd forms of diacharged waste

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residuals that must be assimilated into the en-
vironment (Steele, 1978a). Using the set of seven
mixed coal-resources development alternatives, the
projected residuals given previously in table 5 are
aggregated and compared in figure 5, Total
residuals discharged increase both as a function of
the coal mined and the amount of the coal con-
verted to other energy forms in the basIn. These
projected discharges include both direct and in-
direct impacts. As noted in table 4, the indirect ef-
fects of population, urban development, and ser-
vices constitute the dominant part of several
residual forms (Bower and Basta, 1973). With in-
creasing in-basin coal use. greater amounts of solid
residuals have to be contended with; these
residuals dominate the total discharge loadings
(table 5; fig. 5). As will be discu88ed later, chemical
constituents from these residuals through decom-
position processes may still adversely affect
hydrologic conditions adjacent to disposal areas.
In summary, each cooling technology has both
advantages and disadvantages (Reynolds. 1980).
Some disadvantages must be accepted in order to
obtain the advantages of a given technology. For
example, evaporation ponds or wet-cooling towers
can be used to avoid withdrawing the large
amounts of water needed for once-through cooling.
However, this lower rate of withdrawals is accom-
panied by a higher rate of consumptive use and a
greater amount of dissolved solids requiring dis-
posal. For any given combination of coal uses there
are different water-use and residuals-generation
impacts. Among all of the options considered in
this study, those involving transport of the coal in
raw form have the smallest impacts.

SURFACE-WATER INVESTIGATIONS

By DANIEL P. BAUER

Three study components composed the surface-
water investigations for the Yampa River basin as-
sessment: (1) an anaiysis of the waste-load as-
similative capacity for a reach of the Yampa River
between Steamboat Springs and Hayden, Colo.;
(2) an evaluation of several hydraulic character-
istics of selected subreaches of the Yampa and the
Little Snake Rivers; and (3) a modeling analysis of
several proposed reservoirs. Selected results of each
of these studies are highlighted. Detailed inform a-

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