BULLETIN 665, U. 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 onlj 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 clearlv demonstrated here, as elsewhere, that 
