The Florence tribune., 1900-03-03
SAN CARLOS RESERVOIR Report of MT. J. B. Lippincott on the
 Great Dam. The Most Feasible Point Discovered on
 the Gila River.


 indian Reservation, at the San Carlos Agency, in Gila County, Arizona, at a point where San Carlos River joins the Gila. The Gila Valley, Globe and Northern Railway, which leaves the main line of the Southern Pacific a t Bowie Station and runs to the town of Globe, passes across this reservoir site. The Gila River at this point traverses some spurs of the Pinal range of mountains, and for a distance of 315 } miles below the dam site the river flows in narrow box canyon. This canyon extends to Dudleyville, which point is the upper end ef the Riverside reservoir site. The river then passes through the Riverside reservoir site for distance of 15.5 miles, after which it again enters a canyon, which is the upper end of the Buttes reservoir site. This latter canyon extends to the Dikess which is miles above the guttes dam site. The total length of river from San Carlos dam site to the Buttes dam site is approximately GO miles; about 40 miles of this distance being box canyon, and the remaining portion being valley land, of from to 3 miles in width.
 Six miles below the San Carlos Agency, where the river enters the box canyon and approximately half mile below the beginning of the box, is point where the canyon is about 90 feet wide at the water line and where it's walls rise very abruptly directly from the river. At a point approxi mately 100 feet above the upper face l of the location selected for the dam there has pparently been fault in the rock of the canyon. If the dam were located above this fault, there would be the possibility of leak oc- curing between the strata and of I water passing through the fault to the channel of the river below the dam. If the dam is built where located; this will be obviated.
 The narrewest pertien of the canyon is approximately 400 feetin length, and immediately below this narrow point it widens out to 300 feet at the low water line. This admits of spillway provision as shown in the plan of the dam and described in the account of the dam proper. The dam is located at the point shown in the plan, there fore, in order to obtain better spill way advantage, to secure better foundations aud abutments, and to avoid the leakage through the strata above the line of fault.
 It has been determined that the difference between the amount of water available for storage at San Carlos and the Buttes was 10 per cent, and this deduction of 10 per ceRt has been made in all estimates for the supply at San Carlos as measured at the Buttes.
 The water which is relea sed from the San Carlos reservoir site will pass through approximately 40 miles of box canyon on it's way to the irrigable lands where it is to be used. Compara- tive measurements made at the Buttes and San Carlos during the dry season of the year, when less than 10 second feet of water was flowing in the river at San Carlos, indicate practically an equal amount of water at San Carlos and the Bnttes. There undou btediy isSa substantial loss from evaporation between these points, bat this loss is compensated for by the seepage water which returns from the Riverside Val ley and from the valley above the Buttes dam site. Tn the ease of the Riverside Valley few second-feet of water is used for irrigation, and the return from this irrigation augments the stream. In both valleys, however, the high stages of the river undoubted- 1 ly charge the sand bars and gravel beds with water, and these areg gradual ly drained of during the lower stages of the stream and, as has been stated, give practically an equal amount of water at San Carlos and the Buttes.
 The San Pedro and the other drain- age lines entering the Gila above the Buttes and below San Carlos will con tribute their portion to this stream, unregulated by reservoir built at San Carlos. This water can be used for irrigation around Florence if 1 diverted below. If this volume of water and the return water from l seepage is added to the water which is discharged for irrigation from the San Carlos reservoir site, it is probable that there will be availa ole for irriga- tion ut the point of diversion as much water as would be discharged from the San Carlos reservoir site.
 If the Gila River from the San Carlos dam site to the Buttes dam site is 60 miles in length and 200 feet in width,