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-9- The climate of the region is typical of the Rocky Mountain area. The valley in which Paonia is situated is semi-arid with annual precipitation averaging about 15 inches per year. Mean annual precipitation increases with elevation, reaching approximatey 35 inches per year on th summit of Chalk Mountian. The May-September precipitation is 5 inches for the lowlands and 13 inches for the mountain peaks. This indicates that snowfall patterns play a important part in determining the hydrology of the area. The area is mountainous, with elevations ranging from 5,800 feet at Paonia to 11,150 feet at Chalk Mountain to the North on the Grand Mesa. Slopes range from 0 to 60 percent on the permit area, and elevations range from about 5,700 feet at the loadout facilities area to approximately 8,700 feet at the northern extremity of the permit area. The Orchard Valley mine permit area is drained by tributaries to the North Fork of the Gunnison River. The two major tributaries drain the permit and adjacent areas of the mine, Steven's Gulch, and Terror Creek. Steven's Gulch is an ephemeral drainage which drains the majority of the western mine area. Steven's Gulch has a total drainage area of 6 square miles. Terror Creek drains a small portion (92 acres) of the eastern mine area. This stream may be perennial. Coal Gulch and 4 other small ephemeral streams drain a majority of permit revision area. All of these drainages are tributary to the North Fork. The Orchard Valley loadout is located adjacent to the North Fork of the Gunnison. The North Fork is part of the Colorado kiver drainage system. The North Fork joins with the Gunnison River west of the town of Lazear, Colorado. The total drainage area of the North Fork is 978 square miles. The flow of the North Fork is strongly influenced by Paonia Reservoir. The flow of water in Terror Creek and in the North Fork of the Gunnison are strongly influenced by irrigation structures along these stream courses. The Overland Ditch intercepts and distributes water from the upper reaches of Terror Creek. The flow in the North Fork is controlled by Paonia Reservoir and water withdrawals by several irrigation ditches, Fire Mountain Canal, Stewart Ditch, Farmers Uitch, and Paonia Ditch. In addition, a pipeline aqueduct used by the Pitkin Mesa Pipeline Company follows Stevens Gulch throuyh the permit area. There are several springs and 8 ponds within the permit and hydrologically adjacent area. It appears that, from the data submitted to date, most of these springs and ponds are intermittent and depend upon seasonal precipitation and long-term weather patterns. However, this will need to be confirmed through periodic field checking during both the wet and dry parts of the year. The source of most of the springs appears to be related to landslide complexes, to faults and fractures, to areas of colluvium/alluvium where ground water has accumulated, or to the discharge points of local perched ground water in the lenticular sandstones of the Mesaverde, but drill hole data indicates that this is probably not a significant source of ground water (see pages 61-70, Section 2.04, Volume 8 and Hydrologic Reconnaissance Map in the 1982 Annual Hydrologic Report).