12 
BULLETIN 1430, U. S. DEPARTMENT OF AGRICULTURE 
each year for 40 years. This loss would have an average annual 
value of $25,000 or 225,000 kilowatt-hours a year. Assume that by 
immediate action this loss is prevented. The storage capacity thus 
preserved would at the beginning of the year have a value equiva- 
lent to a sum which, placed at interest at the current rate, would 
amount to $25,000 at the end of the year. The present value of such 
storage capacity as would have been lost at the end of the fortieth 
year would be equivalent to that sum which, put at interest at the 
current rate, would then amount to $25,000. There would be corres- 
ponding values for the losses of the intervening years. The sum of 
these amounts would be the present value of the extended life of the 
NITIAL UTILITY VALUE OR CAPITAL VALUE $2,000,000 
END OF I si DECADE! 
3 
END OF Z n d DECADE 
END OF 3rd DECADE! 
w 
END OF 4i h DECADE 
$500,000 
500,000 $500,000 $500,000 
Utility value or capital value which could not be preserved by a 
protection cover. 
Utility value diminished by silting which might have been preserved 
through checking unnecessary erosion. 
1 | Remaining utility value at end of each decade. 
Fig. 2. — Decrease in utility value or capital value of a reservoir through silting 
reservoir which would result from planting. On this basis the 
present value of the storage capacity having a utility value of 
$1,000,000 at the end of 40 years would be $353,646. (Fig. 3.) 
In this hypothetical case a location in the Piedmont region of 
the Southeastern States may be assumed and the short-leaf or rose- 
mary pine of that region may be selected as a tree for planting. An 
examination of the basin shows that the denuded lands from which 
the larger portion of the turbidity is derived are, if planted in short- 
leaf or rosemary pine, of forest-producing quality No. 2. Without 
thinnings or other care than protection against fire and insects, a 
yield of 17,100 board feet, measured by the Scribner log rule, and 
18% cords of merchantable wood, but of a size too small for saw 
