2 BULLETIN 665. V. s. DEPARTMENT OF AGRICULTURE. 



Fig. 2. — A main canal. This is the common type of ditch which conducts water from 

 the river to the farms. Note the native vegetation and the wild state of the country 

 before development. 



The greater portion of the land in its natural state is covered with 

 a considerable growth of mesquite, huisache, ebony, cactus, and other- 

 trees and shrubs (see fig. 2). The alluvial or lower-lying soils gen- 

 erally support a heavier growth than the lighter textured soils in the 

 northern and western portions of the area. 



The topography of the region (see fig. 3) is level to undulating. 

 In general the land bordering the stream channels or "resacas'" is 

 slightly higher than that at a distance, due to overflows and the re- 

 sulting deposit of sediment near the channels. The elevation varies 

 from about 30 feet above sea level in the vicinity of Brownsville to 

 about 250 feet north of Mission in the western part of the region. 



The drainage of the region is not generally good. The lower lands 

 in the eastern portions, many of which have heavy types of soil, are 

 not so well drained as the lighter textured soils of Hidalgo County. 

 On account of the fact that the banks of the Rio Grande and other 

 channels are higher than the bordering land, the surface water has 

 little opportunity to drain away, so that after heavy rains or exces- 

 sive irrigation water stands in small lakes or ponds for considerable 

 periods. However, the higher land outside of the delta formation 

 has fairly good drainage owing to its comparatively steep slope. 



Artificial drainage by means of surface ditches is being undertaken, 

 particularly in Cameron County. Drainage districts have been 

 formed, and bonds have been issued providing the funds for the 

 ditch construction. The facilities now provided are improving the 

 conditions, and it is only a question of time when artificial drainage 

 will cover practically the whole region. 



In many local areas where open-ditch drainage facilities have been 

 provided but have not proved adequate, tile drainage has been sub- 

 stituted and is meeting the difficulties where satisfactory outlets may 

 be had. It has been clearly demonstrated here, as elsewhere, that 



