The Westwater Canyon Member of the Morrison Formation is the potential source of major supplies of both uranium and ground water in the San Juan basin; development of the uranium is expected to have great impact on the potentiometric surface associated with the water in the Westwater Canyon, and therefore on the supplies available. Most permeability determinations of the unit have been in or near orebodies and appear to have anomalously high values. Comparison of logs indicates that resistivity may be a better guide than so-called "porosity" logs, and that typical values away from areas of ore emplacement may be lower than the averages usually used in analysis of pumping effects. Such values may result in smaller ultimate volumes required for mine dewatering, and may indi ate that the value of the aquifer for major supplies is less than formerly thought.

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