40 BOTANICAL SURVEY OF THE C<EUR d'aLENE MOUNTAINS, 



enough for three or four weeks each year to serve tlie same purpose. 

 These waterways furnish a means to reach most of the heavily timbered 

 districts of the North Fork areas, as they head near Lake Tend Oreille 

 and drain a large part of the basin. 



MINING. 



The area devoted to placer mining lies in the southeastern part of 

 the North Fork basin, and it is therefore only here that the waters are 

 utilized for this purpose. Owing to the fact that the channel of this 

 stream lies so much nearer the eastern rim of the basin than the west- 

 ern, it follows that the tributaries putting in from the maya range of 

 the Bitter Koots are all short and carry only a small volume of water. 

 Added to this is the circumstance that the bottoms of many are filled 

 above the bed rock to a very considerable depth with masses of gravel 

 and bowlders, which permit the stream of water, small in the fall, to 

 sink beneath the surface. The quantity of water is therefore in many 

 places in sufficient for the placer miners in the autumn, and compels 

 them to suspend operations earlier in the season than they otherwise 

 would. 



IRRIGATION. 



Very little of the water is used for irrigation. The insignificant 

 area of irrigated lands lies almost wholly in the South Fork valley. 

 Water is obtained from the small laterals which are not used for mining 

 purposes and are therefore clear and uncontaminated. So long as the 

 bottom lands furnish most of the agricultural areas, irrigation will be 

 dispensed with whenever possible. When the forest is cleared away 

 from the bench lands and they are put under the plow, the necessity 

 of irrigation will be felt. Lands in the Occur d'Alenes from which the 

 forest has been cleared become very dry notwithstanding the large 

 annual precipitation. This happens even in case of swampy ground, 

 if it lies above the level of a running stream. The soil does not retain 

 moisture long owing to its largely siliceous nature. The small side 

 ravines will furnish an easy means of irrigating the bench lands so long 

 as the forest at their sources is not cut off. When that is done, the 

 streams will be dry during the growing season, when most needed, and 

 water must then be elevated from the main streams or brought in 

 ditches or Humes from their higher levels. 



One problem connected with the water supply of the Gceur d'Alenes 

 may be considered here. It is the possibility of utilizing the streams 

 or the stored-up water in Lake Oceur d'Alene for irrigation purposes 

 on the semiarid lands of the plains of the Columbia. In a general 

 way it may be said that this is feasible to some extent. The physical 

 difficulties, however, are so many and so great and the financial suc- 

 cess of an undertaking of this sort so problematical that neither pri- 

 vate individuals nor the General Government are likely to engage in 

 any scheme of this kind for a long time to come, if ever, 



