Documents

Located in southeastern Arizona, this semiarid basin is drained by the San Pedro and Gila Rivers. The Lower San Pedro is a rural landscape with scattered towns and two extensive copper mining and processing operations. Groundwater from three aquifers (floodplain, unconfined basin-fill, and confined basin-fill or artesian) and fractured mountain hardrock is the principle source of water supply.

The contrast rating system is a systematic process used by the Bureau of Land Management (BLM) to analyze potential visual impact of proposed projects and activities.

Our team of conservation biologists and GIS Analysts at Northern Arizona University are creating detailed linkage designs for 16 priority areas highlighted in the Wildlife Linkages Assesment. These plans identify and map multi-species corridors that will best maintain wildlife movement between wildland blocks, as well as highlight specific planning and road mitigation measures required to maintain connectivity in these corridors.

This Executive Order is designed to focus the attention of federal agencies on the human health and environmental conditions in minority communities and low-income communities.

This technical memorandum was prepared to summarize the results of a long-term aquifer test conducted at Resolution Project hydrologic characterization well HRES-4. Well HRES-4 is completed in the Apache Leap Tuff aquifer near Oak Flat, in the upper Queen Creek drainage basin of eastern Pinal County, Arizona.

At HRES-19 and HRES-20, the primary target drilling depth was the contact between the Tertiary Apache Leap Tuff and the underlying White Tail Conglomerate. During drilling operations, data was collected to better characterize the hydrogeologic conditions within the Apache Leap Tuff. The target depth was reached at HRES-19, although the depth to the White Tail Conglomerate was shallower than expected. The White Tail Conglomerate was not reached at HRES-20 due to technical issues encountered while drilling.

Change in rate constant as a function of temperature for a variety of activation energies.

PHREEQC version 3 is a computer program written in the C and C++ programming languages that is designed to perform a wide variety of aqueous geochemical calculations. PHREEQC implements several types of aqueous models: two ion-association aqueous models (the Lawrence Livermore National Laboratory model and WATEQ4F), a Pitzer specific-ion-interaction aqueous model, and the SIT (Specific ion Interaction Theory) aqueous model.

Ground-motion prediction (attenuation) models predict the probability distributions of spectral acceleration values for a specified earthquake event. In this article a large number of strong ground motions are used to empirically estimate these correlations, and nonlinear regression is used to develop approximate analytical equations for their evaluation.

Exposures we have excavated across the San Andreas fault contradict the hypothesis that part of the fault in the Carrizo Plain is unusually strong and experiences relatively infrequent rupture. The exposures record evidence of at least seven surface-rupturing earthquakes which have been approximately dated by accelerated mass spectrometry radiocarbon analysis of detrital charcoal and buried in situ plants.