420 A NATIONAL PLAN FOR AMERICAN FORESTRY 



of the utmost importance to both power and irrigation interests. 

 Run-off from snow melt at the higher elevations remains plentiful well 

 into July, and a rather well-sustained flow continues through the 

 summer in many of the streams from drainage of water that has seeped 

 into the soil. Upward of 2,500 mountain meadows and 1,500 lakes 

 act as natural storage basins helping to maintain this stream flow. 



The mountain areas are largely forested, chiefly with conifers. 

 Interspersed with the coniferous forests are extensive brush fields, 

 many of which, under proper management, could be converted again 

 into coniferous forest. The foothills are covered mainly with brush 

 and chaparral, with lesser areas of woodland and grassland. As a 

 whole the forests of the California drainages amount to approximately 

 29,780,000 acres, this total including timberland, woodland, chaparral, 

 and brushland. 



While the bulk of the forest lands are still virgin, extensive areas 

 show the effects of destructive fires to which they have been subjected 

 in the past and of destructive lumbering. The foothills, in particular, 

 have suffered disastrously from fire. Overgrazing, also, has seriously 

 injured the watershed cover of forested lands. 



Destruction of watershed cover has resulted in abnormal erosion 

 over millions of acres, particularly in the foothill belt. The eroded 

 material is rapidly silting up reservoirs, canals, ditches, and other 

 engineering works, shortening their life or adding to the cost of 

 maintenance far beyond what silting from normal erosion would do. 

 Eroded material also seals the surface soil of gravel beds at the 

 mouths of canyons over which run-off water is spread in order to 

 increase storage in subterranean basins. This method of increasing 

 water storage is used extensively in southern California. The silting 

 up of these gravel beds retards the salvage of flood waters. The 

 heavy draft on underground water supplies is lowering the water 

 level and increasing the cost and difficulty of irrigating from wells. 



The eroded material, added to the rapid run-off from exposed slopes, 

 greatly intensifies the destructiveness of floods. In 1928 North 

 Sacramento and other towns of the Sacramento Valley suffered a loss 

 of $736,000 as a result of floods in the Mokelumne, Consumnes, 

 American, and Feather- Yuba Rivers. 67 Destructive floods have 

 occurred in many parts of the State. 



FOREST COVER IN RELATION TO WATERSHED PROBLEMS IN 

 INDIVIDUAL DRAINAGES 



On the basis of watershed problems and the relation of forest coyer 

 to them, the California drainages logically divide into six units: 

 (1) The San Joaquin River Basin; (2) the Sacramento River Basin; 



(3) the north coast drainages, including that of the Klamath River; 



(4) the central coast drainages; (5) the desert basin; and (6) the south 

 coast drainages. These units differ as to physical and other factors 

 contributing to the influence of forests upon water supply, erosion, and 

 floods, as to the demand for water, and as to other watershed con- 

 siderations. 



California watershed lands are chiefly of three classes forest, 

 range, and agricultural. It is probable that erosion and the influence 



67 Taylor, N. R. "The Floods of March 1928, in the Sacramento Valley," pp. 100-102. Monthly 

 Weather Review, March 1928. 



