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. . . CHAPTER III DESIGNS AND ESTIMATES shale. Suitable materials for the earth lining are available along the canal alignment. A wasteway would be constructed about 450 feet from the head of the canal. The structure would consist of a siphon spillway with two 48-inch by 36-inch cast iron slide gates and a 3-foot by 5-foot rein~ forced concrete box section approximately 160 feet in length. About 300 feet downstream from the wasteway a 12-foot concrete Parshall flume would be installed for measurement of releases from the reservoir. Black Mesa Tunnel The Black Mesa tunnel would have a capacity of 275 second-feet and would convey water about 8 miles from the end of the Black Mesa Canal to a 2,400-foot channel excavated to Crystal Creek approximately 0.7 mile upstream from D,yer Fork. Means of collecting water from Curecanti Creek would be provided by an inclined shaft intercepting the tunnel about 1.4 miles below the inlet portal. Part of the tunnel would be in the stable West Elk breccia and the remainder in the less stable Mancos shale. Gravels sui table as sources of concrete aggregate are available in Crystal Creek, Curecanti Creek, and at the Soap Park Dam site. The tunnel would be concrete ,lined with a 7-foot diameter horseshoe-shaped section. Steel tunnel supports would be required for more than half of its length. The transition from the Black Mesa Canal to the tunnel inlet portal would be made in a rectangular concrete flume section with a 7-foot width. A concrete transition would connect the outlet portal of the tunnel with a concrete chute into the channel to Crystal Creek. The chute would have a baffled apron and a rectangular section with a width of 16 feet. As the Black Mesa tunnel is the major item of project cost, it is planned that more detailed studies will be made of the tunnel loca- tion in the definite plan investigations to determine whether the con- struction cost can be reduced. The outlet portal is in Mancos shale, but the inlet portal is near the contact between the Mancos shale and West Elk breccia. This conta.ct is somewhat irregular so that with more geological studies it may be possible to locate at least the upper por- tion of the tunnel in the more desirable West Elk formation and thus reduce costs or lining and supports. Fruitland Canal The Fruitland Canal would be 22 miles long, extending from the Crystal Creek Diversion Dam to the western end of Upper Fruitland Mesa. For O. '7 mile from the ne" diversion dam to a point near Colora.do state 21