8 BULLETIN 193^ U. S. DEPAETMENT OF AGEICULTURE. 
to determine additional elevations and to check the work. Very 
little time was given to locating property corners, and as most of the 
land is divided into irregular tract^s according to original surveys, 
the cross levels were all located with respect to mileposts or other 
objects of known location along the railroads. The south, end of the 
county is subdivided into square miles which are numbered con- 
secutively, but a great many of the corners are now obscured and 
the level lines were located only approximately. All the streams 
were meandered with compass and stadia, and levels were carried 
on many of the meanders. A sufficient number of channel cross- 
sections were taken to determine the sizes and capacities of the 
streams. For determining the area drained into Jefferson County 
from the west, lines of levels were projected west from the county 
line at intervals of 2 miles and were carried beyond the divide between 
the Trinity and Neches Kivers. Numerous bench marks were estab- 
lished in all parts of the county, the locations, descriptions, and 
elevations of which may be obtained upon request to the Chief of 
Drainage Investigations, United States Department of Agriculture. 
A tract of about 70 square miles lying east of the Texas & New 
Orleans Railroad (Sabine branch) was omitted from this survey 
because the owners furnished a contour map of the tract, which was 
adopted as correct after being checked by several lines of cross levels. 
A number of land maps furnished by the county surveyor and right- 
of-way maps supplied by the raiboads were of great assistance in 
making the survey. 
The map of Jefferson County (fig. 3, in pocket at end of bulletin) 
was drawn to a scale of 3,000 feet to the inch, the outlme being com- 
piled from a War Department map of the Neches River, a Coast and 
Geodetic Survey map of the Gulf shore, and the county surveyor's 
maps of the west county boundary, and a right-of-way map of the 
Southern Pacific Railroad. Upon this skeleton map were plotted all 
the data obtained from the survey and from maps furnished by the 
county surveyor, the railroads, and several irrigation and land com- 
panies. The map shows also the complete system of drainage im- 
provements proposed for the cormty. It should be noted, however, 
that drainage district No. 3 was organized and had begun construc- 
tion before the project was undertaken, and the plans shown for 
that district are not the work of Drainage Investigations. 
THE DRAINAGE PROBLEM. 
As in most other counties of Texas bordering on the Gulf, the 
great areas of undrained and unimproved lands in Jefferson County 
present several problems in their reclamation. The low-lying 
tracts of salt marsh adjacent to the Gulf which are subject to over- 
