29 



III. CONVEYANCE OF WATER FOR THE IRRIGA- 

 TION SYSTEMS OF BRITISH COLUMBIA. 



TYPES OF IRRIGATION SYSTEMS. 



The topography of the land of the irrigated districts of British Columbia 

 is often very rough and the land irrigated is generally rolling as com- 

 pared to irrigated land in most of the arid region of the United States. 

 Because of the character of the topography the construction of an irriga- 

 tion system is expensive and difficult. Ordinarily the main canal which 

 heads at the diversion dam, is excavated on the steep hillsides and con- 

 tinued around the hills, skirting the land to be irrigated. The main laterals 

 or main branches head at the main canal and, where possible, run down the 

 ridges which separate the smaller valleys which make up the entire body 

 of land covered by the system. These laterals either supply directly the 

 farms or are the source of supply for smaller laterals. A large part of the 

 main canal is often excavated in porous material and fissured rock and 

 frequently it must cross canyons or depressions. Open canals have been 

 used where possible; flumes placed on benches cut in the side hill have 

 been used where the side hill was too steep, where the material was too 

 porous, or where the excavation of an open canal was impossible or too ex- 

 pensive, and flumes on trestles or wooden pipes have been used to cross 

 depressions. 



Because of the low winter temperature which -will cause freezing of 

 water in open canals, at least two irrigation companies have used in the 

 place of open canals for the main as well as for the distributaries, a system 

 of wooden pipes buried in the ground below the reach of frost in order that 

 the irrigation system could be used for domestic supply as well. 



The distribution system consists of all laterals and branches necessary 

 to deliver water to each farm. The topography of the land is such that 

 the laterals must often be placed on grades that are too steep for earth 

 ditches and on irregular slopes where the depressions must be crossed by 

 flumes or pipes. Because of this and also because of the small volumes of 

 water usually carried by the laterals, wooden flumes and wooden pipes have 

 been extensively used. Where wooden flumes are used they are placed as 

 much as possible on mud sills resting on the ground and the depressions 

 are crossed on trestles. Where pipes are used they are usually under more 

 or less pressure but occasionally they may be placed practically on grade 

 with very little or no pressure on them, in which case they act more as a 

 covered flume. 



The systems of British Columbia can be classified into the following 

 types based on the form of construction used. 



1st. Those which consist of an open main canal and of open laterals, 

 (either open ditches or flumes), and to which class belong the irrigation 

 systems at Keremeos, Penticton, and Walhachin, and parts of the systems 

 of White Valley Irrigation Company, Summerland, Naramata. 



2nd. Those which consist of an open main canal and of pipe line dis- 

 tributaries such as the Kelowna Irrigation Company and the Fruitlands 

 irrigation system near Kamloops, the latter consisting of a concrete lined 

 canal and cement pipe. 



3rd. Those which consist entirely of pipe lines, both for mains and 

 laterals such as the Kaleden system and part of the Summerland system. 



