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Our results suggest that an increase in temperature will shift the seasonality of runoff, with peak runoff occurring in May rather than June. This change reflects the fact that under higher temperatures more precipitation falls as rain rather than snow, and snowmelt runoff occurs earlier in the year. This result has been seen in several other regional studies (g,g. Gleick, 1986; Bultot, U., 1988). Moreover, because this seasonal result is induced by changes in temperature, rather than more uncertain changes in precipitation, the authors believe it is fairly robust. Temperature increases had a much smaller effect on the White River than on the other basins, which is due to the lower elevation of the White River basin. The NWSRFS model reduces evapotranspiration when snow is on the ground by an amount proportional to the areal snow cover. Because a rise in temperature causes less ground to be covered with snow for fewer days out of the year, evapotranspiration increases while runoff decreases. We would expect this effect to be most significant in higher elevation basins which have proportionately more snow cover. This is in fact the case for the three sub-~sins modeled here. The highest elevation basin, the East River at Almont, also shows the greatest sensitivity to temperature increases. Overall. the Two-elevation model showed an even greater sensitivity to changes in temperature, which may reflect a greater sensitivity to evapotranspiration, although it is difficult to draw a comparison because of the vastly different scale of the Two-elevation model. On a percentage basis. the sensitivity of runoff to temperature in the White River was less than one-half that in the Two- elevation model. All four models showed nearly an equal sensitivity to changes in precipitation. Relative seasonal changes are most significant for the East River, in which 10% and 20% increases in precipitation increase the absolute variation in runoff between spring and fall months. The interpretation of NWSRFS model results in this study must be tempered by three principal caveats. First, as described above. the ability of the NWSRFS model to accurately simulate runoff under conditions of altered climate is subject to some question. Secondly, all climate scenarios were applied on an annual basis. which may be a reasonable approximation for temperature increases but undoubtedly skews seasonal precipitation patterns which are likely to change dramatically under conditions of altered climate. Finally, the historical record was limited to 35 years, which is too short to allow a substantive analysis of natural (non-greenhouse) variation. 39