18 BULLETIN 1456, vl S. DEPARTMENT OF AGRICULTURE 
run-off per square mile becomes 1.86 second-feet, or 1,348.4 acre-feet 
per square mile of affected area per year. 
Run-off data for other portions of the project can not be deter- 
mined accurately principally because of their close proximity to 
nndrained or partially drained areas outside of the Salt River 
project. 
COST OF THE DRAINAGE SYSTEM 
The cost of the completed drainage system for the original area 
of the project is $1,056,157.97, distributed as follows: For pumping 
plants and power distribution system, $891,211.43 ; for closed drains 
in areas D and F, $75,115.19; for general drainage expense, $89,- 
831.35. The total cost has been met by direct, flat assessments 
amounting to approximately $5.20 against each of the 203,000 acres 
of cultivated land now in the Salt River project. If the total initial 
cost were borne entirely by the 64,200 acres of gross land area classed 
as having ground water within 10 feet of the surface and as being 
in immediate need of drainage or drainage protection, it would 
amount to $16.45 per acre ; and if charged against only those areas 
actually water-logged, it would be still higher. 
Considering only that portion of the drainage system consisting 
of the 87 pumping plants operated during the 12 months ended Sep- 
tember 30, 1923, the cost of developing drainage water has been at 
the rate of $2,904.82 per second-foot, this figure being reached by 
placing the cost of that portion of the drainage system at $940,000 
and using the rated capacities of pumping plants as determined dur- 
ing September, 1923. (See Table 4.) 
It is not possible to arrive at the cost of all the drainage pumping 
plants separate!}^, nor to apportion the cost of the drainage system 
according to areas representing the different conditions in the Salt 
River project, since costs were not segregated in this manner for the 
earlier constructed plants. Where the wells are located in gravel 
and bowlder formations which readily give up large quantities of 
water, such as is the case in areas A, B, C, and E, the cost runs as low 
as $800 per second-foot of water, whereas in locations where there is 
little or no gravel, but fine formations that give up water slowly, a 
condition represented by areas T> and F. the cost will run up to 
$5,000 per second-foot of water. The cost of such drainage upon an 
acre basis will vary to a less degree with these conditions, since less 
water will, in all probability, have to be removed from areas under- 
laid by tight formations than from those having extensive strata of 
gravel and bowlders. 
Though these figures do not show the initial cost of drainage to be 
excessive, under more favorable conditions it might have been less. 
Most of the drainage system was installed during a period of high 
prices. With lower prices, the judicious plan followed in construct- 
ing the present system would effect a considerable reduction of the 
cost. 
OPERATION AND MAINTENANCE COSTS 
For the year ended September 30, 1923, the cost of the labor, 
materials, and electric power for the operation of 87 pumping plants 
