transported, only a small fraction could fall out specifically into the Colorado River or the Colorado River Aqueduct, which occupy relatively small areas. In this case a combination of circumstances with an extremely low probability would have to occur Oust as in the previous scenarios) to cause any substantial portion of the long-lived isotopes to become deposited in the Danby Dry Lake sediments. Therefore, the committee concludes that the potential impact of airborne radionuclides on the water quality of the Colorado River or Colorado River Aqueduct is minuscule, even much less than the upper bounding calculation made previously for the direct ground-water pathway scenario to the river.

The committee concludes that:

1. Based on limited hydrologic and geologic data and the topographic conditions, the majority of the ground-water flow beneath the proposed site in Ward Valley appears to discharge at Danby Dry Lake. It cannot be ruled out, however, that some portion of the ground water passing beneath the proposed site may leave the Ward Valley basin.

2. It would not be possible under any reasonable expectation for site characterization either to confirm, or to eliminate with absolute certainty, any of the regional bedrock pathways that have been postulated by the Wilshire group.

3. While there are conceivable, but unlikely, flowpaths for some ground water within Ward Valley to reach the Colorado River, conservative bounding calculations suggest that the potential impacts on the river water quality would be insignificant relative to present natural levels of radionuclides in the river and would meet accepted regulatory health standards.

4. The committee concludes that the potential impact of airborne radionuclides on the water quality in the Colorado River or Colorado River Aqueduct is minuscule, much less than the upper bounding calculation for the direct ground-water pathway scenario to the river.

Bedinger, M. S., Sargent, K. A., Langer, W. H. 1989. Studies of the geology and hydrology of the Basin and Range province, southwestern United States, for isolation of high-level radioactive waste - characterization of the Sonoran region, California. U.S. Geological Survey Professional Paper 1370-E, 30 p.

Brandt, E. C. 1994a. Summary of the California Department of Health Services presentation to the Committee to Review Specific Scientific and Technical Issues Related to the Siting of a Proposed Low Level Radioactive Waste Disposal Facility in Ward Valley, California. October 6, 1994.