Full development of the resources of the Colorado River Basin requires that the waters of the Colorado River system be brought under control by the construction of suitable regulatory structures. Additional storage projects on upper basin streams are necessary for full utilization of its land and water resources. In addition, the production of hydroelectric power and energy will be possible by using the heads made available by the construction of dams and appurtenant works. These dams will also reduce flood damage by providing storage space to hold flood waters. Many thousands of tons of silt are now carried down the Colorado River each year, damaging irrigated areas and curtailing storage capacity in present reservoirs in the lower basin. Proper watershed management is proposed as an aid in the solution of this problem, but storage reservoirs located in the upper basin will aid also by retaining silt which reaches the streams. The reservoirs will have value also for recreational purposes and for the propagation of fish and wildlife.

The Bureau of Reclamation has constructed many multiple-purpose projects throughout the Western States for irrigation, power production, flood control, silt retention, recreation, and fish and wildlife conservation. One of the earliest projects involving power was built in Arizona in 1906 with construction of the Roosevelt power plant on the Salt River. The early plants were used primarily as a source of power for the pumping of irrigation water or for project construction purposes. Later, power was made available to project settlers and to other people in rural areas, towns, and cities where economical service could be rendered.

To date only a small part of the potential hydroelectric power available in the Colorado River Basin has been harnessed by man. (See map, Colorado River Basin, Principal Power Systems, Existing and Potential.) The development and utilization of electric power have progressed at widely different rates in the upper and lower basins. This has been the result of great differences between the two basins with respect to location, climate, population growth, agricultural development, commercial and industrial activities, and transportation facilities. Power development and utilization are far less advanced in the upper basin than in the lower basin and the area

served from it. The discussion on power in this chapter is divided into two sections, the upper basin and the lower basin.

UPPER BASIN

Although the upper basin has great potentialities for the production of electrical energy, it now produces a comparatively small amount and consumes less than it produces. In 1943 the installed capacity of all plants was only 101,082 kilowatts, of which 57,217 kilowatts were in hydroelectric plants.

Some of the energy produced in the upper basin in Colorado is carried by transmission lines eastward over the Continental Divide to the Denver and Leadville load areas, while requirements in the Utah part of the upper basin are largely supplied with energy imported from adjoining areas to the west and north. To date it has not proved practicable to connect the two areas for power supply purposes.

Opportunities exist for the installation of 1,713,000 kilowatts of hydroelectric generating capacity on the Colorado River and its tributaries above Lee Ferry. This is nearly 17 times the capacity of all plants now in the area. The potential power output of these plants would be 28 times the total upper basin power production in 1943. Growing power markets within the basin and in adjoining areas are expected to require eventually the maximum power output of these plants. A system of interconnected transmission lines will be needed to carry power to markets.

Potential power developments described herein indicate the hydroelectric possibilities of the upper basin. Cost allocations have not been included but will be considered in later specific project reports.

The multiple-purpose projects involving power production would create artificial lakes with an aggregate surface area of 555 square miles. In addition to the production of power, many of these reservoirs would have value for irrigation, long-term stream flow regulation, flood control, silt retention, recreation, and propagation of fish and wildlife.

Present Power Development

The extent of present power development in the upper basin has been determined principally by the needs of the mining industry. Coal mines use most of the energy available in the Utah and Wyoming areas, while in the Colorado area coal and metal mines are the largest industrial users. These mining areas are served by the largest utility systems and industrial plants in the upper basin. A number of communities receive service from isolated generating plants, both hydroelectric and fuel-burning. In general, loads are comparatively small and the development of power generating and transmission facilities has been limited in the upper basin.

In Colorado the availability of desirable hydroelectric power sites has resulted in the installation of generating plants and high voltage transmission lines which are mainly to supply loads to the east of and outside the basin area. In Utah the coal mining industry in Carbon and Emery Counties is supplied with power and energy imported over high voltage lines from utility systems located outstide the basin. Wyoming coal mining interests have built their own generating plants to supply their requirements and the needs of people located nearby. Metal mining, which has developed in southwestern Colorado, uses most of the power and energy generated in that locality.

With a total of 101,082 kilowatts of capacity installed in plants in the upper basin, generation in 1943 amounted to 330,149,000 kilowatt-hours. Load requirements (sales plus losses and utility use) for that year totaled 238,870,000 kilowatt-hours, leaving a net export surplus of 91,279,000 kilowatt-hours. The total maximum demand of all loads in the upper basin area was approximately 52,404 kilowatts in 1943.

POWER FACILITIES

Colorado area.-By far the greatest part of the installed electric generating capacity in this area of the upper basin is hydroelectric. Although large coal deposits are available in western Colorado, it has been more economical generally to install hydroelectric rather than coal-burning plants. In some isolated areas where loads are small internal combustion engine plants have been provided.

The principal power systems are those of the Public Service Co. of Colorado, the Bureau of Reclamation, the Western Colorado Power Co., and the Colorado Utilities Corp. The interconnected systems of the Public Service Co., of Colorado, the Bureau of Reclamation, and the Redlands Water & Power Co. together form the largest electric generating and transmission system in the Colorado area and also in the upper basin. These interconnected facilities include some 250 miles of transmis

sion lines, extending eastward from a point a few miles west of Grand Junction to the Continental Divide and on into the Denver metropolitan area. The total generating capacity connected to this system in the upper basin amounts to 45,675 kilowatts, of which 90 percent is hydroelectric and 10 percent is steam-electric capacity. Included in this total area are the 21,600-kilowatt Green Mountain hydroelectric plant (Colorado-Big Thompson project) of the Bureau of Reclamation and the 3,000kilowatt Palisades hydroelectric plant (Grand Valley project) owned by the Bureau but operated by the Public Service Co. of Colorado. The latter plant is considered a part of the company's system in this report. No internal combustion engine-driven generating plants are connected to any of these major systems.

Southwestern Colorado is served by the system of the Western Colorado Power Co., which has 11,700 kilowatts of connected generating capacity, including 9,700 kilowatts of hydroelectric and 2,000 kilowatts of steam-electric capacity.

At McGregor in the northern part of Colorado the Colorado Utilities Corp. operates a 4,250-kilowatt steamelectric plant, with transmission lines extending to nearby communities.

Principal municipal plants are located at Gunnison (550 kilowatts, steam-electric), Delta (1,100 kilowatts, internal combustion), and Meeker (200 kilowatts hydroelectric, and 375 kilowatts steam-electric), all of which are isolated plants. Other generating plants are operated by smaller utilities.

The installed generating capacity of all plants in the Colorado area was 68,429 kilowatts in 1943. Energy generating in that year amounted to 245,083,000 kilowatt-hours, while total load requirements (sales plus losses and utility use) were 88,228,000 kilowatt-hours. The difference of 156,855,000 kilowatt-hours was transferred into the Denver and Leadville load areas over the 100,000volt transmission line of the Public Service Co. of Colorado.

Utah area. Although the Utah area of the upper basin contains a large amount of potential water power and large coal reserves, very few generating plants have been installed, the principal electric loads being supplied with power imported from outside the basin. The largest installation is the 1,200-kilowatt hydroelectric plant of the Uintah Power & Light Co. The Utah Power & Light Co. also operates two isolated plants, one at Vernal (840 kilowatts) and one at Moab (210 kilowatts). The towns of Monticello and Blanding operate small plants to serve their citizens. Two rural electric cooperatives financed by the Rural Electrification Administration have 1,090 kilowatts of installed generating capacity.

Power for the important coal mining area is supplied by two lines of the Utah Power & Light Co., one a 44,000volt line extending from the Olmstead plant near Provo to

Sego and Hiawatha, and the other a 132-000-volt line extending from the Olmstead plant to Helper. These lines are extensions of the company's main Utah-Idaho system.

Only 3,400 kilowatts of generating capacity were installed in the Utah area of the Upper Basin in 1943. Energy generated in that year amounted to 6,677,000 kilowatt-hours. Load requirements totaled 72,253,000 kilowatt-hours, thus requiring 65,576,000 kilowatt-hours to be imported.

Wyoming area. Nearly all power generated in the Wyoming area of the upper basin is from steam-electric plants. Coal mining companies operate the greatest amount of generating capacity. A 20,000-kilowatt plant at Rock Springs operated by the Union Pacific Coal Co. is the largest steam-electric plant in the upper basin. Most of the energy produced by this plant is used for coal mining, but about one-fourth is being distributed by the Southern Wyoming Utilities Co. to other consumers in the Rock Springs area. At Kemmerer the Lincoln Service Corp. operates a 5,500-kilowatt steam-electric plant, and at Diamondville the Diamond Coal & Coke Co. operates a 1,000-kilowatt steam-electric plant, both being used mainly to supply power to coal mines.

The Southern Wyoming Utilities Co. has recently acquired the 1,240-kilowatt capacity steam-electric plant at Green River, Wyo., from the Utah Power & Light Co., and has constructed a transmission line from the plant to Rock Springs.

No municipally owned plants have been installed in the Wyoming area. One system financed by the Rural Electrification Administration operates a 180-kilowatt internal combustion engine plant.

The combined capacity of all plants in the Wyoming area amounted to 28,423 kilowatts in 1943. Transmission facilities are limited, being designed to serve load areas in close proximity to the power plants. Energy generation in 1943 totaled 77,049,000 kilowatt-hours, which met the load requirements of the area.

New Mexico area. This area of the upper basin is served by the Aztec-Farmington division of the New Mexico Public Service Co. Installed generating capacity in 1943 totaled 830 kilowatts of which 280 kilowatts were hydroelectric and 550 kilowatts were internal combustion. The energy generated in that year was estimated at 1,340,000 kilowatt-hours, all of which was consumed in the area. Summary. The amount of installed generating capacity in the upper basin in 1943 is given in table CXXII and the amount of energy generated and load requirements are shown in table CXXIII.

PLANT FACTOR

Although the amount of installed generating capacity is of importance when considering the power facilities

in an area, the real standard of power plant utilization is the amount of energy that can be generated for sale to the ultimate consumer. The degree of plant or system utilization is determined by comparing the amount of energy actually generated with the maximum it is possible to generate with the plant or system continually operated at full capacity. The percentage thus obtained is called the "plant factor."

Plant factors for interconnected systems are higher than for isolated plants because isolated plants need a greater part of their installed capacities as "reserve" to insure continuity of service. Also the operation of plants on an interconnected system may be coordinated to take advantage of the operating characteristics of the individual plants. Recently an annual plant factor of 61 percent was attained by the group of generating plants connected to the system of the Public Service Co. of Colorado in the upper basin, while plant factors on individual isolated plants ranged from 14 percent to 31 percent.

ENERGY PRODUCTION COSTS

Hydroelectric plants.-Hydroelectric plants in the upper basin in 1943 produced electric energy at average costs ranging from 0.65 to approximately 2.7 mills per