| Description |
The purpose of this investigation was to determine the factors in the hydrologic cycle of Middle Canyon, Tooele County, Utah, and to balance the hydrologic budget of the Middle Canyon drainage basin as an aid to future development of the canyon's water supply. A reconnaissance study of the geology of the canyon was made to determine the influence of geologic factors on the hydrology of the canyon. The Oquirrh Mountains is a typical north-south trending range of the Basin and Range province, and is believed to be a block, faulted and uplifted on its western edge and tilted to the east. Middle Canyon is cut entirely into the Pennsylvanian- Permian Oquirrh formation, which is composed of over 16,000 feet of alternating limestones and quartzose sandstones, with the sandstones predominating. Quaternary deposits in the drainage basin, which include alluvial, colluvial, and some glacial material, are thicker in the upper canyon. The greatest concentration of faulting in Middle Canyon is in the upper canyon. These faults are high-angle normal faults with displacements in the order of 100 feet. Jointing is common in the Oquirrh formation, although definite joint systems were not apparent in the Middle Canyon area. Middle Canyon is a structurally controlled drainage basin developed on the sharp decrease in dip where the steeply- dipping northeast limb of the Long Ridge anticline passes into the structural terrace between the anticline and the Bingham syncline. The longitudinal profile and profiles across the main channel indicate that the lower canyon has been rejuvenated, probably as a result of movement on the mountain-front fault at the mouth of the canyon. The discharge from Big Spring, which occurs after the spring thaw in the high parts of the drainage basin, is the main source of supply from Middle Canyon© Examination of the available 11 years of records showed that, per unit of precipitation, the total annual discharge of Middle Canyon has de creased since 1910, Although mining activities in the Oquirrh Mountains have been cited as a possible cause, similar decreases in discharge from many drainage basins in Utah indicate that most of the decrease in discharge from Middle Canyon is due to a change in climate. In Middle Canyon, the geology may have strong local effects-on the hydrology. Leakage could be occurring through fault and fracture zones, joints, or solution channels in limestone beds. The Quaternary deposits of the drainage basin serve as the main storage material for ground water, and alluvial deposits in the main channel transmit water from the upper canyon to the springs and drains at the canyon mouth. The thicker surficial deposits in the upper canyon make it a more important storage area than the lower canyon, and. any zones of leakage in the upper canyon would likely result in greater water loss than would similar outlets farther down canyon. The hydrologic budget for the 1947 water year was calculated by comparing estimates of gains and losses of water in the canyon. In 1947 about 50% of the water estimated to be available for stream flow and channel underflow was unaccounted for, and was assumed to represent leakage out of the drainage basin. Because fault and associated fracture zones account for most of the water encountered in the mine workings of the nearby Bingham district, most of the leakage in Middle Canyon was assumed to be occurring in similar zones. Chemical analyses of water samples taken at various locations in the canyon in the late summer of 1959 showed that the highly mineralized water from the Utah Metals tunnel has little effect on the water quality at the canyon mouth. This indicates that much of the tunnel water is lost by leakage in the upper canyon during the dry part of the year. The future development of Middle Canyon water can best be planned after obtaining additional information on movement of water through the channel fill. Much of this information could be supplied by completing the drilling project that was proposed in 1954 to investigate the hydrologic characteristics of the channel fill in the north-center of section 6, T. 4 S., R. 3 W. |
