176 PLATA DE LOS PIMAS AS A WATER SOUECE. 



of the Copper Mine mountains. In its course southward, its valley hed widens, and travelling 

 over the grits and sandstone, which are loose and porous, it sinks down and disappears. Its 

 volume carried down and the point of sinking varies with the season, some summers higher up, 

 and others lower down ; thus, at some seasons, the crossing at Cook's trail is dry^ and at others 

 a running stream. 



The former was the case this summer, but the water was found about six miles higher up, 

 where it existed as a large collection of fresh standing water in pools or lagoons, surrounded 

 by willow thickets. Four or six miles higher up still, it was a running stream, about 8 feet 

 wide, and from 18 inches to 2| feet deep, travelling 2^ miles per hour. The valley of the river 

 contained everywhere abundance of grass, with cotton-wood and walnut. 



As the river runs in a line of fault in the strata, if it be desired to obtain water in the river 

 valley, at or below where Cook's trail passes it, the river bottom and bed ought to be the spot 

 selected for experiments. This is in a line running south 20° east from the magnetic meridian. 

 Selecting such a line, and getting as close to the west side of a porphyry butte or hill would be 

 the most likely method of tapping the river flowing beneath. A sinking to 12 or 15 feet near 

 Cook's trail, and less than 25 feet for ten miles down, would be the utmost depths required. 

 From the volume of water which the Mimbres carries down, as well as from its uncertain 

 presence at the trail crossings, it would appear necessary to take the river higher up (four miles 

 above camp) and carry it down in a channel, and fill reservoirs or tanks constructed on the line 

 of road. Basins of water, of great capacity, might thus be obtained ; and by taking the river at 

 this point, the supply would be constant the year round. The conveying channel might be an 

 open sequia, but the reservoirs would require to be covered. This stream, because small, is 

 liable to be under estimated in its capability of supplying water. When crossed a few miles 

 above the trail crossed upon this route, it has been found a constant stream by those who have 

 crossed it. As such, Bartlett and Emory describe it, and as such it appeared when visited in 

 the neighborhood of Ojo Caliente. When Major Emory crossed it, he describes it as 15 feet 

 wide and 3 feet deep. Taking the lesser measurement, near Ojo Caliente, at 8 feet wide and 2 

 feet deep, with a velocity of 2^ miles per hour, there is a capacity for supplying water to fill a 

 tank equal to 211,200 cubic feet per hour, or equal to a supply of 3,068,800 cubic feet in twenty- 

 four hours. Thus, a single days' supply would fill a large tank. 



Indeed, the Mimbres might be dammed higher up when the valley is narrow, and thus have a 

 small lake formed, which could be constantly drawn upon, and form a reservoir, whence, by 

 sequias, the wants of a railroad, several miles down, could be supplied. Sequias, though 

 wasteful, are yet efficient for many miles. The town of Dona Ana, on the Eio Grande, is sup- 

 plied by sequias, which come off from the river ten miles above. 



The Ojo Caliente, described page 156, might also, if drawn upon, afford a large supply of pure 

 water, palatable, though hard. ■• 



Ojo de la Vacca, page 155. This spring exists in a depression in the general plain, which is 

 most likely formed by a fault ; in the angle of uptilted strata the water rises. The central 

 spring is surrounded by rush and tule, is about fifteen feet across, and yields but a small excess 

 of water, which, owing to the depressed form of the basin, cannot overflow, and merely soaks 

 the clay in the vicinity. As it does not flow, it does not admit of measurement ; but as the re- 

 moval of 200 gallons in twelve hours' stay did not appear to afiect the spring, perhaps 1,000 

 gallons might be calculated on for every twenty-four hours as the surplus water of the spring. 



The Ojo de Inez was not visited ; it lies further up the canon than the water holes at Camp 



