A NATIONAL PLAN FOR AMERICAN FORESTRY 



419 



of the State. Furthermore, summers are hot. Precipitation occurs 

 below the 2,500-foot contour as rain, between the 2,500-and 5,000-foot 

 contours as rain and snow, above 5,000 feet as snow. Annual precip- 



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CALIFORNIA DRAINAGE! BASINS 



SAN JOAQUIN RIVER BASIN 

 SACRAMENTO RIVER BASIN 

 NORTH COAST DRAINAGES 

 CENTRAL COAST DRAINAGES 

 DESERT BASIN 

 SOUTH COAST DRAINAGES 



PACIFIC 



CASCADE 

 DRAINAGES 



SAN FRANCISCO 



RELATIVE INFLUENCE OF FORESTS 

 ON WATERSHEDS 



^ MAJOR INFLUENCE 

 EH^j MODERATE INFLUENCE 

 E.I.WxJ SLIGHT INFLUENCE 

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FIGURE 11. California drainages. 



itation totals 50 inches or more in the northern Sierra Nevada and in 

 the northern coast ranges. It gradually decreases toward the south. 

 Likewise the proportion of the precipitation that accumulates as 

 snow in the mountains decreases toward the south. In view of the 

 long, dry summers and the present incomplete development of reser- 

 voir storage the heavy winter snow pack, especially in the Sierras, is 



