New Mexico Geological Society Downloaded from: http://nmgs.nmt.edu/publications/guidebooks/18 Ground water in the Window Rock-Lukachukai areas, Navajo Indian Reservation, Arizona and New Mexico Robert J. Edmonds, 1967, pp. 86-91 in: Defiance, Zuni, Mt. Taylor Region (Arizona and New Mexico), Trauger, F. D.; [ed.], New Mexico Geological Society 18th Annual Fall Field Conference Guidebook, 228 p. This is one of many related papers that were included in the 1967 NMGS Fall Field Conference Guidebook. Annual NMGS Fall Field Conference Guidebooks Every fall since 1950, the New Mexico Geological Society (NMGS) has held an annual Fall Field Conference that explores some region of New Mexico (or surrounding states). Always well attended, these conferences provide a guidebook to participants. Besides detailed road logs, the guidebooks contain many well written, edited, and peer-reviewed geoscience papers. 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No material from the NMGS website, or printed and electronic publications, may be reprinted or redistributed without NMGS permission. Contact us for permission to reprint portions of any of our publications. One printed copy of any materials from the NMGS website or our print and electronic publications may be made for individual use without our permission. Teachers and students may make unlimited copies for educational use. Any other use of these materials requires explicit permission. This page is intentionally left blank to maintain order of facing pages. 86 GROUND WATER IN THE WINDOW ROCK-LUKACHUKAI AREA, NAVAJO INDIAN RESERVATION, ARIZONA AND NEW MEXICO By R. J. EDMONDS U.S. Geological Survey, Flagstaff, Ariz. INTRODUCTION WATER-BEARING UNITS IN THE The area along Navajo Route 12 from Window Rock WINDOW ROCK-LUKACHUKAI AREA to Lukachukai has a more abundant surface-water supply SUPAI FORMATION. than most areas in the Navajo Indian Reservation (fig. The Supai Formation of Permian and Pennsylvanian age 1 ). Streams, such as Tsaile, Wheatfields, and Whiskey consists of brownish-orange, very fine to fine-grained, silty Creek, flow perennially in reaches extending several miles sandstone interbedded with red siltstone and mudstone west of the Chuska Mountains. Precipitation is about 22 (Read and Wanek, 1961, p. 3-4). The Supai crops out in inches per year in the Chuska Mountains and at the higher an oval-shaped area on the crest of the Defiance Plateau altitudes along the Defiance Plateau. Generally, ground and overlies the Precambrian rocks (Cooley and others, water is available, but most wells produce only a few 1967). gallons per minute from depths ranging from less than The Supai Formation generally has a low permeability 100 to more than 1,500 feet. and yields water slowly, although the permeability may The Chuska Mountains are capped by the Chuska increase locally in fractured zones. Wells that penetrate Sandstone—the principal aquifer in the mountains. the Supai in the Defiance Plateau yield as much as 5 to Springs issue from the base of the Chuska Sandstone and 8 gpm. The Supai Formation is recharged directly by furnish perennial flow to the streams along the west side precipitation and runoff in its area of outcrop. Ground of the mountains. No wells have been drilled into the water moves outward from the crest of the plateau. Nat- Chuska Sandstone because the surface water in the ural discharge occurs from springs that yield from less than mountains supplies the present demand. 1 gpm to more than 300 gpm, and perhaps by slow upward In most of the Defiance Plateau, the principal aquifer leakage into the De Chelly Sandstone. Water from the is a combination of the De Chelly Sandstone and the Supai Formation in the Defiance Plateau is of good chem- Shinarump Member of the Chinle Formation. The Supai ical quality and generally has a dissolved-solids concentra- Formation is tapped by a few wells along the crest of the tion of less than 500 ppm (parts per million ). plateau where the De Chelly and Shinarump have been removed by erosion. DE CHELLY-SHINARUMP AQUIFER In the valley of Black Creek, between the Chuska Moun- The De Chelly Sandstone of Permian age and the Shin- tains and the Defiance Plateau, the principal aquifer is the arump Member of the Chinle Formation of Triassic age alluvium. The alluvium combines with tuff to form the are hydraulically connected and form a single aquifer in major aquifer in Buell Park on the west side of the valley. the Window Rock-Lukachukai area. The Moenkopi For- The De Chelly-Shinarump aquifer dips eastward beneath mation, an aquiclude separating the De Chelly and Shin- the valley and is penetrated at depths of as much as 750 arump to the south and west, is absent in the Window feet by wells that produce as much as 50 gpm (gallons per Rock-Lukachukai area. minute). The Sonsela Sandstone Bed of the Petrified The De Chelly is a pale-orange, very fine to medium- Forest Member of the Chinle Formation is tapped by a few wells that produce less than 10 gpm. grained, well-sorted, generally firmly cemented, quartz South of the Chuska Mountains and east of the valley sandstone. It is 450 feet thick in a well at Window of Black Creek, the two chief aquifers are the Gallup Rock (Cooley and others, 1964, p. 59 ), and 750 feet thick Sandstone and a combination of the Westwater Canyon in Canyon del Mucrto on the west side of the Defiance Member of the Morrison Formation and the Dakota Plateau (Read and Wanek, 1961, pl. 2). The De Chelly Sandstone. Artesian conditions prevail in these aquifers, crops out on most of the south and west sides of the which are penetrated at depths of from 500 to more than Defiance Plateau, in a narrow belt on the east side, and 2,000 feet below the land surface. The Crevasse Canyon in Canyon de Chelly and its tributaries. and the Menefee Formations overlie the Gallup Sand- The Shinarump Member of the Chinle Formation is stone and supply water to windmill wells for stock and composed of light-gray, fine to very coarse grained, poorly domestic use. The water-bearing Entrada and Cow Springs sorted sandstone and conglomerate. The grain size and Sandstones underlie the Westwater Canyon-Dakota aqui- permeability of the Shinarump vary locally. The thickness fer, but these formations have not been developed. of the Shinarump is also variable, but it is generally from 1. Publication authorized by the Director, U.S. Geological Survey. about 50 to 250 feet thick. It crops out in most of the NEW MEXICO GEOLOGICAL SOCIETY-EIGHTEENTH FIELD CONFERENCE 87 109.3d 109°15 109. 108%5 3V 30 N il 0 I? 41% LUKACHUKAI as • C.- ./. , n 3-7 3,15 0-i) „Ft.) Sf 3C.) C-C\ , CHEL.2(...__< ON CpNy ... ..., 0 o fo ,c,..tis`,, 1.- ..\-<: -Z" A \ 1 . -CIA— --57 — ...., TODILTO 1- RED 1 -0 O LAK ,..., SAWMILLM;t. BUELL PARK 1-- .PARK__. 1 $ Ill NAVAJD 1:,---„ , I I TOHATC1-(15 .--I.. _1--\.. \t. 01 ... :. D Vi i3I C 35 45 U FOR DEFIAPC E 1 41 (- TWIN LAKES SCHOOL 1 I W INDOW ROCK 0 () --- \____-------- _ ? r u0.53 FIGURE 1. Window Rock—Lukachukai Area, Arizona and New Mexico. 88 NEW MEXICO GEOLOGICAL SOCIETY-EIGHTEENTII FIELD CONFERENCE northern part of Defiance Plateau and caps a ridge along issues from small springs on the west side of the Chuska the west side of the valley of Black Creek. Mountains. Wells drilled into the De Chelly-Shinarump aquifer in The chemical quality of water in the Sonsela Sandstone the Window Rock-Lukachukai area generally produce Bed is variable in the Window Rock-Lukachukai area, but from less than 5 gpm to about 50 gpm. The De Chelly is the water is probably suitable for stock, at least in places water-bearing in all of the area, but the Shinarump is dry near the outcrops. Chemical analyses of water from the in most of the northern part of the defiance Plateau. The Sonsela indicate that the dissolved-solids concentration is Shinarump is more permeable than the De Chcllly; generally less than 2,500 ppm; water from some springs where the Shinarump is saturated, it probably contributes has a dissolved-solids concentration of less than 1,000 ppm. more water to wells than the De Chelly. Sodium, bicarbonate, and sulfate are the principal ions in In the northern part of the Defiance Plateau, ground solution. water occurs under water-table conditions at depths of ENTRADA-COW SPRINGS AQUIFER from 200 to 500 feet in the De Chelly Sandstone. Wells that penetrate the Dc Chelly in this area generally produce The Cow Springs Sandstone and the underlying upper less than 10 gpm. On the east side of the Defiance Plateau, sandy member of the Entrada Sandstone of Jurassic age water occurs under artesian conditions, because the De are combined as a single aquifer in this report, although Chelly-Shinarump aquifer is confined by overlying imper- they are separated by the Todilto Limestone and the Sum- meable beds of the Chinle Formation.