Geological Survey Water-Supply Paper 1475-H Availability of Additional Water for Chiricahua National Monument Cochise County, Arizona

The availability of water for the monument depends on the amount of precipitation that falls on the watersheds of the two principal drainage systems—Bonita and Rhyolite Canyons—and the ability of the rocks to store and transmit water. The volcanic rocks yield only small quantities of water because their joints and fractures, although well developed, either are not well interconnected or have a small total storage capacity. The alluvium is more permeable than the volcanic rocks, but owing to its limited extent and thickness it is able to store only small amounts of water.

SURFACE FLOW

The streamflows in Rhyolite and Bonita Canyons are reported to be markedly different. Although both drainage systems are believed to receive about equal amounts of precipitation, the stream in Rhyolite Canyon is reported to flow continuously for several months after summer rains begin. In contrast, the stream in Bonita Canyon has through flow only occasionally although some reaches of the creek flow continuously during the wet season.

The dissimilarity in runoff between Rhyolite and Bonita Canyons may be due to differences in the degree of fracturing of the volcanic rocks or differences in thickness of the alluvial fills in the two watersheds. The difference in runoff is also evident in the presence of springs and seeps along Bonita Canyon and their absence along Rhyolite Canyon. In addition, there is a much heavier vegetative growth along Bonita Canyon than along Rhyolite Canyon.

SPRINGS AND SEEPS

Three known springs or seeps along Bonita Canyon are within the monument property. Shake Spring, in the SE1/4SE1/4 sec. 24, T. 16 S., R. 29 E., supplied all the water for the monument at the time of this investigation. An infiltration gallery constructed in Bonita Canyon at the spring site collects most of the flow. From the gallery a 1-1/2-inch pipeline carries the water about 2 miles to the surface-storage tanks near the headquarters. The collected discharge varies in direct proportion to the rainfall and has been estimated in reports of the Park Service to range from about 2 to 12 gpm; it is not known to have gone dry. Nearly permanent flow and heavy vegetative growth below the spring indicate that some discharge is being lost to underflow and evapotranspiration. Bridger Spring, sometimes called Bonita Spring, in Bonita Park in the SW1/4SW1/4 sec. 18, T. 16 5., R. 30 E., was reported to have continuous flow, but it was dry when visited on June 26, 1959, and no moisture was revealed by shallow digging. Park Service records contain only a few references to the amount of flow from Bridger Spring—generally less than 2 gallons per hour. No data are available regarding the permanency of the seep in Bonita Canyon, in the SW1/4NW1/4 sec. 25, T. 16 S., R. 29 E., but water was standing in an area of about 25 square feet and the wetted area extended for about 10 feet down the canyon on June 24, 1959, when Bridger Spring was dry. Water from the seep in sec. 25 enters the alluvium of Bonita Canyon and therefore could not be measured.

Two other possible sources of water for the monument were visited. The first was a seep in the SW1/4NE1/4 sec. 35, T. 16 S., R. 29 E., about half a mile south of the monument headquarters. Water was standing about 1 inch deep over an area of about 20 square feet, but the discharge could not be measured when visited. The second possible source of water, especially for the development of Echo Park which is a trail rest area about 2 miles east of monument headquarters, is a small discharge from the base of a dam across Echo Canyon in the SW1/4NW1/4 sec. 30, T. 16 S., R. 30 E. The dam is about 1 mile northeast of the confluence of Echo and Rhyolite Canyons. The reservoir behind the dam is about 20 feet long. It is filled with sand and gravel nearly to the crest of the dam. It could not be ascertained by inspection whether the sand and gravel cover a collection box or fill the reservoir to its bedrock base and no records or other information about the construction of the dam could be found. A small amount of water discharges from a valve at the base of the dam, but the total supply of water available is not known.

WELLS

The 6 wells in the monument area—2 on Park Service land and 4 on private land—are within 1 mile of each other near the monument entrance and headquarters. All the wells are reported to fluctuate seasonally, but measurements were available from only two wells. The dug well in the SW1/4SW1/4 sec. 26, T. 16 S., R. 29 E., is at an altitude of about 5,230 feet and had a water level of 21.4 feet below land surface on June 25, 1959. No further information regarding this well is available. The dug well at the monument headquarters in the NE1/4NE1/4 sec. 35, T. 16 S., R. 29 E., is 29.4 feet deep. The altitude of the well is about 5,280 feet, and on June 25, 1959, the water level was 22.8 feet below land surface. The Park Service drilled two wells in 1938. The first, across Rhyolite Canyon about 350 feet northeast of the headquarters office, was drilled in alluvium to a depth of 115 feet. The well was destroyed when bailer tests indicated that only a very small amount of water could be produced and, hence, it was not counted as one of the six wells, although its approximate location is shown on plate 17. The second well, which was drilled to a depth of 55 feet, is 12 feet east of the monument dug well. The well is cased and capped.

A series of tests were made by the Park Service in 1958 on the 55-foot drilled well to determine its yield. A jet pump was set at the bottom of the hole and in the first test the well was pumped dry in 13 minutes at an estimated discharge of 30 gpm. The water level at the beginning of the test was 14.7 feet. Smaller discharges were used in succeeding tests and the well was pumped dry each time. The amount of recovery of the water level between periods of pumping was not recorded. The dug well, 12 feet from the pumped well, also went dry during the tests. An earlier test of the dug well was made in 1956, during which the well was reported to have been pumped for 24 hours at a rate of 18 gpm with only a few feet of drawdown. These data are insufficient to analyze the hydrologic characteristics of the alluvial fill of Bonita and Rhyolite Canyons.