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OOClH? (2) orographic storms that produce localized mountain-induced precipitation. Not all parts of these storms are seedable. However, new developments in instrumentation and measurement techniques have advanced our ability to determine which parts are seedable. It is no longer necessary to rely on indirect indices of physical conditions, an approach that has proven to be inaccurate and inefficient. Advances in onsite processing, display, and analyses of data provide a basis for the development of opportunity recogni- tion and reaction systems. These new capabilities make it possible to reinforce the evaluation by documenting the chain of physical events that lead to snowfall. This increases the confidence that cloud seeding is responsible for increased snowfall. The primary evaluation will concentrate on quantifying precipitation increases in the demonstration sites. Precipitation-runoff relationships and watershed models will be used to express these precipitation increases in terms of streamflow. Because the anticipated effects of seeding are smaller than the year-to-year variations in natural snowfall, carefully applied statistical techniques are required to detect the seeding-induced changes. Although a goal of the demonstration program is to provide as much water as possible, a randomly selected portion of the seedable events will be left unseeded to facilitate an unbiased, timely evaluation of seeding effects. The randomiza- tion procedures and the treatment units will be chosen to balance the requirement for maximum water production against the need to achieve confir- mation of the technology as soon as possible. Although the primary statisti- cal analysis will use hourly precipitation data, a secondary analysis will consider seasonal streamflow from treated and untreated subbasins. In view of the much smaller sample size, such a streamflow analysis is not expected to be convincing by itself. However, it is expected that the streamflow analysis and the rigorous statistical precipitation analysis will reinforce one another. Another important feature of the demonstration program is the use and refine- ment of suspension criteria. Seeding will not take place when weather conditions that could be detrimental to public safety or could cause property or environmental damage are expected. Seeding will be suspended when severe avalanche danger exists and when the seasonal snowpack is much above the long-term average. In addition, seeding and other activities will be sus- pended under any special or unusual circumstances that are considered hazardous. Transferability studies will focus on collection and analysis of those data required to permit the design and implementation of a well-founded cloud seeding program throughout the Colorado River Basin. Initial efforts will center on adapting existing technology to the two demonstration subbasins. The preferred area for this portion of the study is the Grand Mesa. Follow- ing this, major emphasis will shift to studies in the other major water- producing subbasins. Two principal areas of investigation will be pursued to identify the most cost-effective implementation procedures for each of the subbasins: (1) transport and diffusion of seeding agents, and (2) seeding opportunity recognition and response studies. 3