ages. The Mancos River area will be fully supplied upon completion of construction now under way.

Several small ditches divert annually an average of about 4,000 acre-feet of water from the San Juan River Basin to the Rio Grande Basin. Authorized for construction by the Bureau of Reclamation as a part of the San Luis Valley project is the Weminuche Pass diversion, whereby an open canal from the headwaters of Pine River will divert an average of 21,000 acre-feet annually into the Rio Grande Basin. Replacement storage will be required to protect future developments in the San Juan Basin.

The Western Colorado Power Co's. 4,500-kilowatt Tacoma plant located on the Animas River 20 miles above Durango generates most of the electric energy produced in the San Juan River Basin. Stream flow through the plant is regulated by the off-stream Electra Lake Reservoir of 21,000 acre-feet capacity, supplied from Cascade and Elbert Creeks. Three other hydroelectric plants in the basin have capacities totaling only 450 kilo

watts.

Western Tributaries.-In this area about 30,000 acres are irrigated, of which 14,600 acres are served from Fremont River; 8,000 acres from Muddy River, a tributary of the Fremont; 4,400 acres from Escalante River; and 3,000 acres from Paria River. A minor diversion from the Sevier River in the Bonneville Basin to Paria River lands is the only importation of water into the Colorado River Basin. Nearly all canals, ditches, and reservoirs have been constructed by individual or community enterprise. The four largest reservoirs are on the Fremont River and have combined capacities of 14,400 acre-feet.

Several smaller reservoirs are distributed throughout the area, but there is insufficient stored water to supply the late-season demands of most lands.

Hydroelectric power is generated at only one small plant in this area having an installed capacity of 150 kilowatts. This plant, supplemented by a small diesel installation, provides energy for the upper Fremont River area. Most other populated areas are served with electricity transmitted from adjoining regions.

Summary. Present irrigation developments in the San Juan division are summarized in the following tables which show the larger reservoirs, irrigated areas, estimated consumption of water in the division, water imported into the division, and water exported from the division to adjacent basins.

POTENTIAL DEVELOPMENT OF WATER RESOURCES

Control and use of present surplus flows of the San Juan division and diversion of an average of 154,400 acre-feet annually from the Grand division could bring a full irrigation supply to 367,160 acres of arable dry land and supplemental water to 73,220 acres now inadequately irrigated. With an installed capacity of 965,000 kilowatts potential power plants in the division could produce 5,115,000,000 kilowatt-hours of firm energy annually. Most all developments would provide, in some degree, other benefits for flood and silt control, recreation, and propagation of fish and wildlife.

Potential transmountain diversions to the Sevier River and Rio Grande Basins would export annually an average

Dulce - Chama - Navajo Project. A reservoir at the Navajo site on the Navajo River, two low diversion dams, two main canals, and a distribution system would be required to irrigate 15,900 acres of new land, including 3,700 acres along the Navajo and Little Navajo Rivers and in the Coyote Park area of Colorado and 12,200 acres in New Mexico extending from Dulce to and slightly across the low ridge which forms the Continental Divide west of Chama, N. Mex. Supplemental water also would be provided for 1,950 acres now irrigated with only a partial water supply. A reservoir with a capacity of 20,000 acre-feet at the Navajo site would be sufficient for this project but a greater capacity, probably 50,000 acre-feet, would be desirable for joint use with the South San Juan project or the alternative San Juan-Chama diversion project.

South San Juan Project. South of San Juan River in New Mexico, extending southeast from Bloomfield to the Continental Divide near Cuba and westward from Largo Canyon to Chaco River, is a vast area of undeveloped and unclassified land, part of which is considered arable by local people. The land is high, ranging in elevation from 5,600 feet near the San Juan River to 8,000 feet at the Continental Divide. A reconnaissance indicates that irrigation water could best be supplied by a gravity diversion from headwaters of the San Juan River. The aqueduct would head on the West Fork of the San Juan River in Colorado, run southward to a point near the Continental Divide 15 miles west of Chama, N. Mex., continue southwest along the west slope of the Divide to a point near Cuba, and thence turn northwest onto project lands. The main aqueduct would be nearly 300 miles long. Storage reservoirs would be required on the West and East Forks of the San Juan River and on Rio Blanco and Navajo River. The development probably would be limited by the available water supply to 75,000 acres. Carracas project. This project would provide water for 840 acres of new land and 190 acres inadequately irrigated along the San Juan River between Gato (Pagoso Junction) and Arboles, Colo. Construction of a low diversion dam on the river and a canal to carry water to the land would be required.

O'Neal Park project. The 5,820 acres of new land and 1,780 acres now partially irrigated, possible of development through construction of this project, are located in O'Neal Park and near the head of Stollsteimer Creek west of Pagosa Springs, Colo. A 32,200-acrefoot reservoir (13,600 acre-feet active capacity) at the offstream O'Neal Park site, supplied by a new canal from the Piedra River, and a distribution canal system would be required.

Hammond project.-Natural flow of the San Juan River could be diverted into a future canal at a low diversion dam to be constructed near Blanco, New Mexico, and used to irrigate a 3,700-acre strip of arable dry land on

the south side of the river near Bloomfield, New Mexico. Shiprock project.--A compact area of arable land, comprising 70,000 acres, is located within the Navajo Indian Reservation south of Shiprock, N. Mex., and west of Chaco River. Irrigation of these lands would require a 125,000 acre-foot reservoir (100,000 acre-feet active capacity) at the Arboles site on the San Juan River near the Colorado-New Mexico State line, a diversion dam near Blanco, and a gravity conduit extending 75 miles to the land. A pump lift of 100 feet would be needed to irrigate part of the land above the conduit.

Emerald Lake project. On the Pine River, a tributary of the San Juan River, is a power site in the San Juan mountains 25 miles northeast of Durango, Colo. Two natural lakes, Emerald and Divide, could be used as reservoirs by the construction of a dam at the outlet of each. With a combination of collection conduits, three short tunnels, a siphon, and penstock the flow would be available for power production under a static head of 1,973 feet. A power plant with an installed capacity of 15,000 kilowatts could produce 72 million kilowatt-hours of firm energy annually. The development would be multiple purpose for power production and flood control.

Pine River project extension.-Surplus flows of Pine River and its tributaries, supplemented by storage from the existing Vallecito Reservoir, could be used to irrigate 15,100 acres of new land owned by both Indians and whites and would provide supplemental water to 1,200 acres now irrigated. Ten thousand acres of this land are located west and southwest of Ignacio, Colo. To serve this area construction of a diversion dam at the head of the existing King Consolidated Canal, north of Bayfield, Colo., and enlargement and extension of that canal would be required. The remaining 5,100 acres are in small tracts scattered throughout irrigated lands in the vicinity of Bayfield, Ignacio, and Arboles, Colo. Rehabilitation and extension of 10 existing canals would be necessary to irrigate these lands.

Florida project.-Along the Florida River and on adjoining mesas in the vicinity of Durango, Colo., are 6,300 acres of new land and 13,800 acres of irrigated land with only a partial water supply. Additional water for full irrigation of these lands could be provided by construction of a dam to store 23,300 acre-feet at the Lemon site on the Florida River and enlargement and extension of existing distribution canals.

Animas-La Plata project. Supplemental water for 24,700 acres of insufficiently irrigated land in the La Plata River Basin and a full supply for 86,300 acres of new land in that basin and adjacent areas, including 25,500 acres under the Monument Rock project on the Navajo Indian Reservation, could be furnished by this project. In addition power could be produced and flood damage would be mitigated. Nine reservoirs would be needed, three of which would be primarily for power production.

A collection aqueduct could bring the flows of Mineral Creek and Cement Creek to the Howardsville Reservoir (54,000 acre-feet capacity) on Animas River which would be connected by a pressure conduit to a 12,000-kilowatt power plant downstream at Silverton, Colo., operating under a static head of 542 feet. Farther downstream on the Animas River between Sultan Creek and Whitehead Gulch is the Silverton Reservoir site (28,000 acre-feet capacity). From this reservoir, water could be released through a tunnel to Lime Creek, where a reservoir (30,000 acre-feet capacity) could be provided to receive this regulated flow plus unregulated inflows from Cascade Creek through a collection conduit and tunnel. From Lime Creek a short tunnel through West Needle Mountain would lead to a power plant on the Animas River where the static head would be 1,155 feet and the installed capacity 40,000 kilowatts.

The two power plants in this development would have installed generating capacities aggregating 52,000 kilowatts and annual firm production of 192 million kilowatt hours. A reconnaissance survey of other tributaries of the San Juan River would probably reveal additional power sites.

The Teft Reservoir (140,000 acre-feet capacity) on the Animas River, 20 miles north of Durango, would collect water released in the winter from the three power reservoirs. Heading at the Teft Reservoir, the main project canal would continue on the west side of the Animas River intercepting flows of Hermosa, Junction, and Lightner Creeks and storage releases from the Hermosa Park Reservoir (25,000 acre-feet capacity) on Hermosa Creek. The canal would cross the Animas-La Plata Divide northeast of Fort Lewis College and extend across the La Plata River Valley to the Dry Side area, serving lands along its course. It would continue thence southwest along the Mancos-La Plata Divide to the head of Salt Creek, which creek in turn would supply the Monument Rocks Reservoir (19,800 acre-feet capacity) and project lands below it, located north of Shiprock. Long Hollow Reservoir (14,000 acre-feet capacity), 12 miles southwest of Durango, would be connected with the La Plata River by inlet and outlet canals. Another canal diverting from Long Hollow Creek would irrigate the McDermott-Farmington Glade area near the ColoradoNew Mexico State line. State Line Reservoir (32,000 acre-feet capacity), astride the State line on La Plata River, would serve valley lands and regulate flows into an outlet canal extending southwest to the Meadows Reservoir (11,400 acre-feet capacity) and to lands in the Meadows area.

McElmo project.-A reservoir of 3,000 acre-feet capacity on Mud Creek would provide adequate water to supplement the supply and improve the quality of water for 1,000 acres of irrigated land in McElmo Canyon, Colo.

Montezuma Valley project extension.-Water from Dolores River in the Grand division now irrigates 30,000 acres of land in Montezuma Valley in the San Juan River Basin. Storage to supplement natural flow is provided at the Ground Hog Reservoir on the headwaters of Dolores River and at the offstream Narraguinnep Reservoir in the San Juan Basin. Expansion of the project to include another 10,000 acres would be possible by enlargement of the Narraguinnep Reservoir to store 5,700 acrefeet in addition to its present 9,300 acre-feet, creation of 8,000 acre-feet of storage at Totten Lake, also in the San Juan Basin, and extension of distribution canals.

Dolores project.-A storage reservoir of 185,000 acrefeet capacity (100,000 acre-feet active capacity) at the McPhee site on the Dolores River in the Grand division about 10 miles below Dolores, Colo., and a canal, leading from that reservoir and crossing the divide into the San Juan Basin by means of a 4,400-foot tunnel, could provide water for 40,000 acres of arable land located in the Dove Creek area. About 32,500 acres are in Colorado and 7,500 acres are in Utah.

Blanding project. Thirty-eight hundred acres of land on the mesa between Recapture and Cottonwood Creeks in the vicinity of Blanding, Utah, are partially irrigated from direct flows of Recapture Creek. The diversion of water from Indian Creek, a tributary to the Colorado River in the Grand division, and a storage reservoir on Recapture Creek would provide supplemental water to these lands. A collection ditch on the headwaters of Indian Creek, a mile-long tunnel to Recapture Creek, and a 1,000-acre-foot reservoir on Recapture Creek about 6 miles north of Blanding would be required. Construction of the tunnel has been started by local interests.

Navajo Indian projects.-The Office of Indian Affairs has outlined 57 small potential projects in the San Juan Basin to benefit lands in the Navajo Indian Reservation. Five are located in the Red Wash drainage area, 21 in Chaco River Basin, 21 in the Chinle Creek area, 4 along the San Juan River, and 6 in miscellaneous drainage areas. The developments involve the construction of additional canals and offstream reservoirs to store flash flows. By means of these projects supplemental water would be provided for 14,600 acres now irrigated and a full irrigation supply would be furnished to 34,200 acres of new land.

Bluff project. In the canyon of the lower San Juan River is the Bluff dam site near Comb Wash, 13 miles below Bluff, Utah, at a river elevation of 4,135 feet above sea level. A reservoir capacity of 3,000,000 acre-feet would require construction of a dam to raise the water surface to an elevation of 4,475 feet. A power plant with an installed capacity of 52,000 kilowatts could produce 289 million kilowatt-hours of firm energy annually. The reservoir also would have value for flood control and silt retention.

Goosenecks project. At a point on the San Juan River 43 miles below Bluff, Utah, at a river elevation of 3,958 feet is the Goosenecks site. A dam to raise the water surface to an elevation of 4,135 feet would provide a reservoir with storage capacity of 500,000 acre-feet. The power plant installed capacity would be 30,000 kilowatts and the annual firm production 152 million kilowatthours.

Slick Horn Canyon project.--Named Slick Horn because of the seepage from oil sands that coats the water and canyon walls, this reservoir site is on the San Juan River 70 miles below Bluff, Utah, at river elevation of 3,750 feet. Here a dam could be constructed to raise the water to a maximum elevation of 3,958 feet and form a reservoir with storage capacity of 300,000 acre-feet. The capacity of the power plant would be 30,000 kilowatts and the annual firm production 176 million kilowatt-hours.

Great Bend project.-Thirty miles above the mouth of the San Juan River is the Great Bend reservoir site at elevation 3,498 feet. Backwater from the potential Glen Canyon Dam would flood the site to a maximum reservoir elevation of 3,528 feet. However, much of the time this site would not be flooded as the average Glen Canyon Reservoir elevation would be only 3,461 feet. The Great Bend Dam would raise the reservoir water surface to an elevation of 3,750 feet forming a reservoir with a capacity of 1,000,000 acre-feet. A power plant with an installed capacity of 36,000 kilowatts could produce 203 million kilowatt-hours of firm energy annually. Below this site the San Juan River empties into the colorado River 78 miles above Lee Ferry, Ariz.

Piedra-Rio Grande diversion project.-Two reservoirs in the Piedra River Basin and a tunnel through the Continental Divide would be required to export an average of 85,000 acre-feet of water annually from the Piedra River to the Rio Grande Basin. Replacement storage reservoirs would be necessary to provide water for future developments in the San Juan Basin.

Alternative plans.-Three projects for exportation of waters of the San Juan Basin are possible but allocation of water to them would restrict supplies for some of the other developments outlined for use of water within the basin. For this reason these projects are presented as alternative possibilities but are excluded from the tables summarizing potential basin developments. However, detailed investigations may show construction of some of these to be desirable.

The Animas-Rio Grande diversion project could export annually an average of 130,000 acre-feet of water from the Animas River watershed above Silverton, Colo., to the Rio Grande Basin. Fourteen miles of collecting canal leading to a reservoir of 54,000 acre-feet capacity on the Animas River at Howardsville, Colo., and a 13mile tunnel through the Continental Divide would be re

quired. There is insufficient water for both this project and the Animas-La Plata project as outlined.

San Juan-Chama diversion project could export 300,000 acre-feet of water annually from headwaters of the San Juan River to the Rio Grande Basin. Reservoirs would be provided on the east and west forks of the San Juan River, and on the Rio Blanco and Navajo River. An aqueduct would collect the water and convey it through the Continental Divide to the head of the Rio Chama, a tributary of the Rio Grande. Benefits from use of this water need not be limited to downstream water users in the Rio Grande Basin in New Mexico, but users in the San Luis Valley of Colorado could also benefit by exchange. As in other potential trans-mountain diversions, replacement storage would be required to compensate San Juan Basin interests. This project would utilize the same water supply as would the South San Juan project, consequently both could not be constructed.

San Juan-South Fork diversion project could export annually an average of 53,000 acre-feet of water from the headwaters of the San Juan River above Pagosa Springs, Colo., ot the south fork of the Rio Grande. The diversion system would consist of a feeder canal 2.6 miles long from the west fork of the San Juan River to Beaver Creek, and a tunnel 10 miles long from Beaver Creek to the south fork of the Rio Grande, with a 1-mile branch tunnel intercepting the flow of Wolf Creek. Water available to the South San Juan project or the San Juan-Chama diversion project would be depleted by the amount diverted to the south fork of the Rio Grande.

Western Tributaries

Three projects for further irrigation development in these stream basins and one for export of water to the adjoining Bonneville Basin are outlined.

Fremont project.-A supplemental water supply for 9,000 acres of irrigated land and a full supply for 1,000 acres of new land located in the vicinity of the towns of Fremont, Loa, Lyman, and Bicknell would be provided by a 4,000-acre-foot reservoir on Fremont River at the Mill Meadows site, 4 miles northeast of Fremont, and a 2,000-acre-foot reservoir on Road Creek, a tributary of Fremont River near Loa.

Torrey project.-A 2,000-acre-foot reservoir at the Torrey site on Fremont River would by exchange furnish supplemental water to 1,200 acres in the vicinity of Torrey, Utah. The reservoir water would be released to downstream lands in exchange for increased upstream diversions to the existing Torrey Canal.

Escalante project. An impounding dam on Escalante River near Escalante, Utah, could provide 25,000 acre-feet of storage capacity (18,000 acre-feet active capacity). With a feeder canal to the reservoir from Pine Creek and an outlet canal cut through a natural embank

ment on the south side of the reservoir, a full irrigation supply could be furnished 3,000 acres southeast of the

town.

Muddy Creek Diversion project.-Lack of storage sites on Muddy Creek to regulate water for downstream use suggests the possibility of exporting surplus flows of that stream west to the Bonneville Basin. By construction of 11 miles of feeder canal and a 2.2-mile tunnel through the mountain divide, an average of 7,000 acre-feet annually could be exported to Twelvemile Creek, a tributary of the Sevier River.

Main stream of Colorado River

Two prospective sites for power developments are located on the main stream of the Colorado River below Green River and above Lee Ferry and therefore are in the San Juan division.

Dark Canyon project. This dam site on the Colorado River in Utah is 186 miles by river above Lee Ferry, Ariz., and 74 miles by road and trail southeast of Hanksville, Utah. Much of this region is unexplored. The Dark Canyon site has been photographed from the air by the National Park Service and surveyed and photographed by the Geological Survey.

A dam raising the water surface 432 feet from the present river elevation of 3,528 feet up to 3,960 feet would provide a reservoir storage capacity of 1,400,000 acre-feet of which 1,100,000 acre-feet would be active. The reservoir, confined between canyon walls would extend up the Colorado River to the Moab Dam site and up the Green River almost to Green River, Utah. A power plant at the dam with an installed capacity of 350,000 kilowatts could generate 1.8 billion kilowatt-hours of firm energy annually. The project would also have value for silt retention, flood control, recreation and, hold-over storage to satisfy flow requirements of the Colorado River Compact at Lee Ferry.

Glen Canyon project.-A few miles south of the UtahArizona State line and 4 miles up the Colorado River from Lee Ferry, Ariz., is the Glen Canyon site at river elevation 3,127 feet. A dam to raise the water surface 401 feet would provide a reservoir of 8,600,000 acre-feet capacity with active storage of 6,300,000 acre-feet. The power plant installed capacity would be 400,000 kilowatts and the annual firm production 2.2 billion kilowatt-hours. The lake would extend 182 miles up the Colorado River to the Dark Canyon dam site and up the San Juan River 30 miles to the Great Bend site. Only 10 miles from highway U. S. 89, this lake would have unusual recreational possibilities. The reservoir would also be useful for silt retention, hold-over storage, and flood control.

An alternative plan would place a higher dam at the Glen Canyon site to raise the water 605 feet above the