Weather Bureau at Red Bluff since 1878 is 18°. These temperatures permit the growth of all of the products of the State. A compilation of physical statistics for FIG. 5.-General map of Sacramento River drainage basin, California. Red Bluff by Mr. Maurice Connell, observer for the United States Weather Bureau, is given in this report. They show in detail the conditions here referred to. H. Doc. 44, 58—2———7 Surrounding Sacramento Valley on the north, east, and west are high ranges of mountains culminating in Mount Shasta at the northern apex of the valley, with an elevation of 14,380 feet. Upon the crest of these ranges, the Sierra Nevada on the east and the Coast Range on the west, the precipitation is much greater and occurs usually in the form of snow, which remains at the higher altitudes until melted by the summer sun. As the mountains are higher to the north and east of the valley than to the west, the precipitation is greater there, the temperature is lower, and the snow remains unmelted until later in the summer. The stream conditions resulting from these physical conditions may readily be inferred. From the higher Sierras the creeks begin to rise with the fall rains, and the precipitation in the foothills causes them to maintain their flow throughout the winter. Under normal conditions, however, they reach stages of maximum discharge in the spring and early summer, when the snows at the higher levels are melting. They reach their lowest stages in September. On the western side of the valley the streams issuing from the Coast Range, to which class Stony Creek belongs, flow from lower and warmer levels. Consequently, the precipitation is more often in the form of rain and the snow is more quickly melted. The resulting stream flow therefore is more irregular and the maximum periods of flow are in winter and early spring. These Coast Range streams are reduced to very low discharge throughout the summer months, and their proper utilization is largely dependent upon the construction of reservoirs for the conservation of the winter water. There is therefore a cool, wet winter in the valley, followed by a hot, dry summer. The Sacramento and its eastern tributaries are strong streams during the winter, spring, and early summer, and have relatively low discharges in September and October, while the western tributaries are normally high in winter and early spring and almost dry in summer. These conditions not only demand the irrigation of the valley, but furnish the opportunity therefor. * * * The higher marginal valley lands are better drained and warmer than the lowlands. They are not so well adapted to the growth of grain, as the soil is not so strong, but it is believed that with irrigation they would be among the finest fruit lands of the State, capable of producing the olive, vine, and orange. The Valley of the Po in northern Italy is the greatest artificially watered district of Europe. In this region irrigation has been practiced continuously for over one thousand years. The values of water and of irrigated lands have continually increased, and to-day it stands as an example of most intensive cultivation, supporting 391 persons per square mile in the irrigated district. The following interesting comparison may be made between the climatic conditions of Milan, in the heart of this district, and those in the upper Sacramento Valley. R. Baird Smith, lieutenant of engineers, British service, in a work entitled “Italian Irrigation," is the authority for the statements on Italian irrigation. The record of rainfall and temperature for Milan was obtained from the United States Weather Bureau. It probably extends back into the eighteenth century. For monthly maximum and minimum records at the head of the Sacramento Valley, see the Red Bluff record given later in this report. Comparison of climatic conditions in Sacramento Valley and in northern Italy. The minimum temperature at Woodlands is not available. The lowest temperature recorded at Red Bluff by the Weather Bureau is 18° above zero. It will be noted that there is double the rainfall in Lombardy that there is in Glenn County, and a large portion of it occurs in the summer, yet irrigation is accepted as decidedly profitable and water rights are increasing in value. This being true, irrigation certainly should be of marked benefit in the Sacramento Valley. STREAM MEASUREMENTS. Following is a seven-year record of the mean discharge of Sacramento River at Jellys Ferry, obtained from the records of the United States Geological Survey: Estimated mean annual discharge of Sacramento River at Jellys Ferry, or Iron Canyon, a For details of discharge measurements, see Water-Supply and Irr. Paper No. 81, p. 186. 17, 653 12, 370 RESERVOIR SITES. The Coast Range on the west side of the valley offers many opportunities for the storage of water. The investigation shows that there are two reservoir sites which have not previously been surveyed by the Geological Survey; one on Puta Creek, at Guenoc Valley, about 40 miles above the foothills, and one of unusual capacity in the main river canyon 7 miles above Red Bluff. The water supply of Cache Creek, including Clear Lake, is discussed by A. E. Chandler in WaterSupply and Irrigation Paper No. 45. Stony Creek Basin is fully described by Burt Cole in Water-Supply and Irrigation Paper No. 86. The accompanying map (fig 5, p. 97) shows the area covered by the investigation. The first exploration was undertaken on Puta Creek, and a reservoir site in Guenoc Valley was surveyed in July and August. The basin comprises an area of about 2,000 acres of cultivated flat land. Back of this is a gentle slope which has not been cleared, and still farther back are steep hills which are thickly wooded with oak and chaparral. GUENOC RESERVOIR. The map of the Guenoc reservoir shows the contours at 10-foot intervals. Following is a table showing the capacity at each contour: Capacity of Guenoc Valley reservoir site. The dam site is about 415 feet wide at the 80-foot level, and about 100 feet wide at the base, as shown in the accompanying plan and cross section. Excavation with pick and shovel was made on each side of the canyon at the dam site, in order to ascertain the character of the rock, and what appeared to be solid rock was found in every case within 4 feet of the surface. The stream bed is full of sand and bowlders, the bowlders being too large to admit of boring except by machinery. At a point in the reservoir about a mile southeast of the |