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<br />water. Neither can the effect of temperature rise from
<br />industry cooling water and thermal power installations
<br />be fully identified or evaluated, although probable
<br />locations and effects were considered. As pointed out
<br />under the discussion on electric power water supply,
<br />each thermal powerplant operation considered in the
<br />fu ture must be analyzed for its effect on water tempera-
<br />ture and water quality deterioration. The study did not
<br />consider temperature reductions resulting from reservoir
<br />releases. However, design of outlet structures can com-
<br />pensate by maintaining temperatures at desired levels.
<br />Projections of water quality control needs in terms of
<br />low-flow augmentation were developed concurrently
<br />with other water requirements during plan formulation
<br />since it was necessary to consider alternative programs
<br />for providing the most efficient solutions.
<br />
<br />NAVIGATION
<br />
<br />As presented in the appendix, "Present and Future
<br />Needs," a review of navigation improvements on the
<br />Missouri River was made, generally with respect to the
<br />adequacy of the existing navigation project between
<br />Sioux City and the mouth of the Missouri River and a
<br />general identification of future water transportation
<br />opportunities in the basin. With respect to the existing
<br />project, the study shows that flow rates of 25,000 to
<br />31,000 cfs at Sioux City, Ia. and 31,000 to 41,000 cfs at
<br />Kansas City, Mo., would be adequate to support a 9-foot
<br />navigation channel. In the event future upstream uses
<br />should deplete the water supply as to seriously impair
<br />the services of the navigable waterway, a number of
<br />alternative courses of action are available. These include
<br />abandonment of the waterway as a transportation mode,
<br />canalization of the river, shortening the navigation
<br />season, or increasing the water supply by water imports.
<br />Recent studies indicate that extension of the up-
<br />stream limit of the navigable waterway from Sioux City
<br />to Gavins Point Dam is economically feasible and could
<br />be implemented in the future. In addition, probable
<br />need for navigation improvements on the Kansas River
<br />below Turner, Kans., and on the lower 3 miles of the
<br />Grand River in Missouri are indicated. Plan formulation
<br />studies, therefore, considered not only additional naviga-
<br />tion improvements that may be warranted, but also the
<br />future water supply situation as well as the legal
<br />framework affecting implementation.
<br />
<br />FLOOD AND EROSION CONTROL
<br />
<br />Analyses of the flood and erosion problems were
<br />based on identification of areas susceptible to flooding
<br />or erosion and estimates of losses that could be expected
<br />in these areas under current conditions. Sufficient data
<br />were available to make a fairly definitive study of
<br />
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<br />
<br />current levels of flood damages and gully erosion. For
<br />streambank erosion, however, a generalized assessment
<br />was made to determine the miles of channel undergoing
<br />erosion and the amount considered to be serious.
<br />F or floods and erosion, projected levels of damages
<br />were based on broad indicators of economic activity
<br />expected to prevail in the future and with protection
<br />afforded by existing projects. The projected damage
<br />levels, which for the most part reflect historic trends, are
<br />considered to give a reasonable picture of the magnitude
<br />of future flood problems in the absence of any future
<br />programs, either structural or non-structural. Such
<br />projections remove possible bias during plan formulation
<br />and permit the formulation of a program encompassing
<br />both structural and non-structural measures. The projec-
<br />tions, therefore, reflect continued economic expansion
<br />with no dampening factors. On the other hand, they do
<br />not infer an absolute "need" or "demand" that must be
<br />met by developmental or management programs. Plan-
<br />ning criteria presented in the next chapter outlines
<br />acceptable levels of damage reduction for consideration
<br />during plan formulation. On the basis described, tables
<br />25, 26, and 27 summarize current and projected future
<br />damages stemming from floods, streambank erosion, and
<br />gully erosion, respectively.
<br />The average annual values do not provide a total basis
<br />for planning purposes. In many instances, positive flood _
<br />and erosion control programs result in an enhancement
<br />of the affected area, usually through a change in land
<br />use. Measurement of this effect can be made by
<br />determining the income differences brought about by
<br />the program. This leads to the need to correlate flood
<br />and erosion protection programs with such other pro-
<br />grams as increased agricultural production through
<br />
<br />i1nproved technology and irrigation practices, restrictive
<br />
<br />management of flood plains versus urban expansion, and
<br />other uses of flood plain areas. The advantages of such
<br />correlation are not directly obvious from projected
<br />damage levels. For example, the reduction of sedimen-
<br />tation in storage reservoirs permits not only longer
<br />useful reservoir lives, but also better water quality for
<br />recreation and fish and wildlife and other uses. The
<br />factors outlined are applicable to single-purpose as well
<br />as multi-purpose programs.
<br />
<br />LAND CONSERVATION AND DRAINAGE
<br />
<br />As stated in chapter 4, about 60 percent or 165
<br />million acres of the 274 million acres of privately owned
<br />land in the basin requires the installation of conservation
<br />practices to provide adequate protection and to maintain
<br />or improve fertility. Of this amount, 103 million acres
<br />need the installation of management-type practices,
<br />while 62 million acres need management plus the
<br />installation of vegetative or mechanical-type practices. In
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