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<br />Criteria were developed for suspending seeding when snow- <br />pack became excessive or when avalanches or flooding were <br />considered probable. The transport and diffusion of seed- <br />ing material also were studied. <br /> <br />Evaluation. - The goal of the evaluation function was to <br />assess the effects of seeding on the amount of precipita- <br />tion associated with weather systems and the effects of <br />additional precipitation on the environment (fig. 1-13). <br />Precipitation data, temperature and moisture distributions <br />in the atmosphere and other data were analyzed using <br />hydrologic models, cloud and precipitation models, and <br />airflow models, plus standard statistical techniques. The <br />relationships between avalanches and cloud seeding were <br />studied, including techniques to forecast avalanches and <br />techniques to cause controlled slides (fig. 1-14). <br />Satellite-interrogated data platforms were evaluated in <br />cooperation with the Lfu~DSAT program. The ecological <br />program evaluated the effects of the project on elements <br />thought to be (1) indicators of possible impact, (2) of <br />economic importance, or (3) of particular ecological <br />significance. <br /> <br />The evaluation showed a balance of seeding-caused increases <br />and decreases in snowfall, and identified those weather <br />situations which could be treated for enhanced snowfall, <br />snowpack and spring runoff. "The overall potential for <br />precipitation enhanceDent was assessed in this evaluation <br />study at around 10 percent," Aerometric Research, Inc., <br />said in its final report. [121] "This translates into an <br />overall streamflow enhancement potential of around 19 per- <br />cent," the report's executive summary said. From the east- <br />ern San Juan Mountains alone, that would mean an average <br />annual increase of 196 million cubic meters (159.000 acre- <br />feet) of new water in the San Juan River Basin and an <br />increase of 186 million cubic meters (151,000 acre-feet) in <br />the Rio Grande Basin (do~nwind of the study area), the report <br />said. <br /> <br />The principal conclusions arrived at on the basis of the <br />overall evaluation of seeding effects on the amount of <br />precipitation were: <br /> <br />1. Positive effects (increases) occurred when seeding <br />was conducted during in-bounds conditions. conditions <br />which met the specified seeding criteria. Negative <br />effects (decreases) occurred when seeding was conducted <br /> <br />1-29 <br />