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

The limited quantitative records regarding water-level fluctuations, pumpage, spring discharge, and surface runoff makes it necessary to suggest a program limited to the development of known spring facilities and test drilling for well sites. All water sources examined within the monument are subject to wide seasonal fluctuations. In general, ample water is available in the monument to meet its needs, but several sources may be necessary to insure an adequate present and future supply. The alluvium will probably prove to be the best and most permanent source of water because it yields water more readily than the consolidated rocks. In addition, ground-water storage should be sufficient to provide minimum requirements during dry periods.

IMPOUNDMENT OF SURFACE FLOW

Runoff in Rhyolite Canyon could be dammed at any of several points to provide reservoir storage for water that could be diverted by pipeline and gravity flow either into the present surface-storage tanks or directly to the headquarters area. The dam on Echo Canyon could be enlarged to provide water for Echo Park.

DEVELOPMENT OF SPRINGS AND BEEPS

The collection gallery at Shake Spring could be enlarged to capture additional water now lost to underflow and evapotranspiration. The seeps in the SW1/4NE1/4 sec. 35, T. 16 S., R. 29 E., and in the SW1/4NW1/4 sec. 25, T. 16 S., R. 29 E., discharged water during an unusually dry period; hence they should be explored and their discharges measured to determine if they are adequate to materially augment the water supply.

In order to assure ample supplies of water during dry periods the present storage facilities should be enlarged to accommodate the needs of the monument for at least 15 days.

DEEP TEST WELL

The possibility of obtaining a reliable source of water by drilling a deep test well through the volcanic rocks into the underlying sedimentary rocks can be only surmised because of the lack of subsurface geologic and hydrologic data. The thickness of the volcanic rocks and the depth at which the underlying sedimentary rocks will be encountered are not known. The sedimentary rocks are exposed on the east side of the monument where they dip westward under the volcanic rocks. Their next exposure is about 40 miles to the west in the Dragoon Mountains on the west side of Sulphur Springs Valley. The thickness of the volcanic rocks at the monument headquarters is estimated to be about 1,500 to 2,000 feet, on the basis of the projection of dips of the sedimentary rocks about 3 miles to the northeast. However, all the faults in the area are upthrown to the west which may materially lessen the thickness of the volcanic rocks in the headquarters area.

Data from deep wells in Sulphur Springs Valley do not indicate conclusively what might be found at similar depths at the monument headquarters, but the information does indicate the possibility of the presence of deep aquifers. Two or more of these deep wells near Willcox about 35 miles northwest of the monument obtained water under sufficient artesian pressure to cause it to flow at the surface from the consolidated sedimentary rocks at depths of about 1,400 feet. The water contained 1,300 ppm (parts per million) of dissolved solids. It is not known from what part of the sedimentary sequence the flows were obtained. Another deep well about 14 miles north of Douglas, about 40 miles south of the monument, obtained a flow of hot water from Paleozoic sedimentary rocks below a depth of about 1,600 feet. The water contained about 900 ppm of dissolved solids.

Correlation of the rocks in these wells is not possible, and the presence of deep aquifers elsewhere in the area cannot be predicted. Also, the hydrologic characteristics of the sedimentary rocks underlying the monument headquarters may vary greatly because of differences of cementation, compaction, metamorphism, and structure. The drilling of any deep well should be considered strictly an exploratory test hole.

TEST DRILLING IN THE ALLUVIUM

The alluvium along Bonita Canyon between the monument entrance and headquarters should be tested to determine its water-bearing characteristics. If permission can be obtained to make pumping tests on the existing private wells in sec. 26, T. 16 S., R. 29 E., it may be possible to determine the hydrologic characteristics of the alluvial aquifer in the area. Otherwise it will be necessary to drill test wells as near to Bonita Canyon as possible below its confluence with Rhyolite Canyon. The wells should be tested thoroughly to check the feasibility of developing a permanent water supply from the alluvium.

Bridger Spring was dry when visited, but a shallow well in the alluvium along Bonita Canyon in Bonita Park, augmented by adequate storage facilities, might yield sufficient water for picnic-ground purposes.

Other sites where the alluvium may be tested are: (a) in Bonita Canyon below its confluence with Surprise Canyon but above the present public campground sewage system; and (b) in Bonita Canyon in the SW1/4NW1/4 sec. 25, T. 16 S., R. 29 E., east of the fault and south of the seep.

These wells should be drilled and tested under competent technical supervision. Well-cutting samples should be collected during the drilling and an accurate driller's log should be obtained. The well testing should be planned to determine the amount of water available and the effects of long-term pumping, particularly at the well site near the public campground sewage system where pumping may reverse the water-table gradient sufficiently to allow pollution from the leaching field. The pumping tests should be made during a dry season.