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DO;J03S / CHAPTER I DROUGHT INFORMATION NEEDED THE I)ROUGBT COMES Except for a n4rr0.... coastal strip in the Pacific Northwest, the wes,tern. states have an arid climate ' and largely depend ;on winter snowfall in the higher mountains for water supply, Most irrigation projects and metropolitan ""as depend on reservoirs to store the spring runoff felr later use during the long dry summer. The larger reservoirs are designed to hold water from wet petiods for use during dry periods several years later, ~ut each dry year brings more dry reservoirs and increases the probability of severe water shortage. In the winter of 1975-76, the normal eastward movement of stormj, coming inland from the Pacific was so often blocked by an extraordinarily stable high pressure ridge off t.e California eoast that precipita- tion amounts were near record lows in California and the states to its east, The early winter months were much wetter in the l'acific Northwest, but by the new year the high pre$ure ridge was often extending further north and p1\':"ipitation amounts were running below normal throu~h the more northern tier of states as well. During tha~,winter and the following summer, the most severe eff~s were felt by those depending on a dry land famjing or a range economy and on municipalities that i did not have enough reservoir storage or ground"iater resources to provide carry. over storage from Ejarlier, wetter years. Tropical stornls caused some unusual rainfall amounts in the areljs near the Mexican border in the summer of 1976, b\1t by early winter, it was quite evident that the sta.le high pressure conditions of the previous winter hajl not only returned but that the ridge was even mOrl> persistent and extended further north than during the previous winter. Normal snowpacks were riot accumulating in any of the western mountains ivithtypicalamounts ranging from 30 to 50 percent of ~ver.ge. Streamflow forecasts for many areas were 2Oito 30 percent of average. At many locations, these amdunta were the least they had been in as much as 100 years of record. By December,' the ski resorts were suffering severe losses, wintllr grain growers knew they would be fortunate to ge~ any kind of crop, and livestock ranchers were seIl{ng extra animals in an effort to save enough feed for their basic herd. The more severely impacted municipalitiea were by Marcb rationing water or charging severe penalties for wasteful use, Irrigators and municipalities throughout the west knew that unless a change in the, weather pattern brought more precipitation, aIi would be experiencing severe water shortage by the end of the summer. Percentages of normal precipitation did generally increase somewhat through the late spring and summer, but shortages remained severe. In fact, it was largely carryover storage. in th.e larger reservoirs and groundwater mining that saved the day. To the east, simultaneous severe drought conditions were experienced during the winter and spring in the upper midwest, centering in Minnesota, Wisconsin, and Iowa, but water supply conditions improved substantially during the summer, The southeast, centering in Virginia, the Clp'Oiinas, and Georgia, experienced severe drought conditions later in the summer and in the early fall, While these states were not in the geographical area on which this study coneentrated, their drought conditions fostered na- tionwide participation in the project. Below normal precipitation amounts continued in the mountain areas critical to water supply through the fall of 1977. By late fall, however, it was obvious that the southwestern desert areas were experiencing above normal precipitation, and significant flooding occurred in Arizona and Southern California, By February, the rains had extended throughout the west, and even the most severely drought impacted communities were dropping water rationing and related measures. As the rainy season ended, it was obvious that many areas would complete the water year with precipitation amounts at or near reeord levels. The drought is now history, but all of those who worked on this project hope that it proves to be a history from which westerners learn many valuable lessons on how to make better use of available water when future shortages occur. GOVERNMENT RESPONDS By February 1977, the drought situation was causing sufficient concern throughout the 11 western states to motivate government response, Most 1