By BULLETIN 1358, U. S. DEPARTMENT OF AGRICULTURE 
MUD-REMOVAL METHODS 
The plow-and-scraper method of removing mud is generally the 
most effective and economical. The slip type is preterred to the 
fresno when the scraper must be frequently shifted into position by 
hand when moving mud too soft for teams to cross. A gasoline 
tractor equipped with cable and gouge bucket, a steam shovel, and © 
similar engineering devices would move the mud, but the expense and 
difficulty of handling heavy machinery over rough country have 
prevented their eeneral employment. 
If all the mud or silt removed is not needed to repair or enlarge 
the old dam or to construct a small dam for a settling basin, the 
surplus should not be dumped above the dam where it may be washed 
back into the basin. If it is planned to build the dam higher, fur- 
rows should be plowed along its top. Material dumped at the top 
of an old embankment and allowed to slide down the slopes is diff- 
cult to pack. If conditions permit, it is better pr actice to begin at 
the bottom and build up a bench on the water side of the dam wide 
enough for teams to pass over and thus pack the material as the 
work. progresses. The old dam which it is planned to enlarge should 
be roughened to secure a satisfactory bond between old ‘and new 
earthwork. 
In certain cases, where an adequate new spillway can be con eter cd 
at a higher level and the 6ld one successfully dammed, it may be 
cheaper to raise the embankment than to remove the mud. The 
difficulty of working with mud is avoided, and the work need not 
be delayed until the reservoir basin is completely dry; but the deep 
deposit of unremoved mud frequently offers a trap in which weak 
cattle will bog and perish. The method is not generally to be 
advised. 
SILT CONTROL MEASURES 
Deposits of silt in reservoirs filled by storm waters can not be com- 
pletely prevented, but there are various practical measures by which 
the rate of silting may be slowed down. 
MAINTENANCE OF MAXIMUM VEGETATIVE COVER ESSENTIAL 
The most important silt-control measure is to build up the vege- 
tative cover on the watershed and maintain it at its maximum 
density. In the Southwest grasses are of most importance for hold- 
ing soil, but trees and shrubs play their part, especially in prevent- 
ing the washing of watercourses and in catching silt and other 
débris. To maintain grass and other vegetation at the maximum 
stand means (1) prevention of overgrazing (Pl. XVI, fig. 1), (2) 
keeping the number of animals to a basis of conservative utilization 
of the range forage, (8) proper seasonal use, (4) relieving areas 
about permanent Water during the spring and summer growing 
periods of the plants by moving as many animals as possible to 
temporary water supplies, (5) securing adequate distribution of 
livestock over the whole range, and (6) lessening excessive con- 
centration by every practicable means, especially by eliminating as 
far as possible salting at permanent water. It should be the aim each 
year to leave from ‘10 to 25 per cent of the herbage of the more 
