Irrigation By Pumping 



JOSEPH JACOBS, United States Reclamation Service 



In the popular mind, Irrigation implies a gravity orsurface— catchment system for deliv- 

 ering water to the land, but in recent years pumping has come more and more to be rec- 

 nized by engineers as a legitimate and profitable means of supplying water for irrigation, 

 and it is destined to grow in importance with the development of cheaper power. Lands that 

 lie beyond the economic scope of gravity supplies are often entirely reclaimable by 

 pumping, and numerous cases are of record where both systems being available, the 

 advantage as to first cost and to operating expense has been with the pumping plant. 



Although taken up seriously by California only within the past few years, irrigation 

 by pumping is by no means a new art. 



Windmills have been used extensively owing to their ease of installation and their 

 almost negligible operating expense. They should be used only where a comparatively 

 regular wind can be depended on, and for greatest economy should be supplemented 

 with storage reservoirs or tanks to conserve the full capacity of the mill during hours 

 and days when no irrigating is done. The mills in common use are 12 to 16 inches 

 in diameter, and, depending on the lift, will pump sufficient water to irrigate from one 

 to three acres of land without storage or from three to nine acres where storage is 

 provided. Their first cost of $30 to $40 per acre irrigated makes them applicable to the 

 irrigation of small areas, but it is believed that with larger and more powerful mills 

 grouped about ample reservoirs and where proper wind conditions prevail, they can be 

 made to compare favorably with the more approved types of pumping plant. 



Of the many types of pumps available and in use the most common is, perhaps, the 

 centrifugal pump. They are made on the coast in standard sizes, ranging from 2 to 15 

 inches for diameter of suction and discharge pipes, and on special order can be made 

 any size required. The first cost will depend on size of plant and type of motor used. 

 For small plants capable of serving 100 acres or less, the first cost has usually been $12 

 to $15 per acre, and operation and maintenance from $2 to $3 per annum per acre 

 irrigated. For larger plants the relative cost has been materially lower. 



A recent estimate made by the United States Geological Survey for an extensive 

 pumping system to serve some 300,000 acres of land in the San Joaquin Valley, indi- 

 cated the first cost of plant to be about $4 per acre and the annual cost of operation 

 and maintenance to be about 50 cents per acre-foot, or say $1 per year per acre irrigated. 

 When it is borne in mind that the average cost of installation of gravity supply sys- 

 tems in California has been about $13 per acre and the average annual charge for irri- 

 gation $1.60 per acre, the great possibilities of pumping can be appreciated. 



The gasoline engine has proven very efficient and cost per acre by this method 

 should not exceed $6.00 per year, an entirely economic figure for valuable fruit crops. 



With the present price of fuel oil, the cost per acre irrigated with steam power 

 should be from $1.50 to $3.00 per year for lifts ranging from 25 feet to 70 feet. 



The utilization of our mountain streams for the development of hydro-electric 

 power plants has in it the most potent promise for the extension of irrigation by pump- 

 ing. With the present commercial rates for electric power and the low lifts that very 

 generally obtain throughout our interior valleys, the cost of pumping by this system 

 should rarely exceed $1 per year per acre. 



The scope of this article will not permit a review of the extent to which pumping 

 is already practiced in this State. There are, however, numerous plants operating, as, for 

 instance, in the Santa Clara Valley, where there are about 2000 plants, most of which 

 have been installed within the past five years; in the Woodland district, where nearly 

 1000 acres have been brought under cultivation by pumping; in the vicinity of Corning, 

 at the northern end of the Sacramento Valley, in the San Joaquin Valley, and very 

 extensively in the southern part of California, where unusual energy has been dis- 

 played in conserving the water supply, it is estimated that they have installed suffi- 

 cient pumping capacity to increase their supply by some 20,000 miner's inches, thereby 

 saving to themselves and to the State valuable orchards which would otherwise have 

 perished. 



Considering the available supply of cheap fuel and the numerous electric power 

 plants now developing, probably in no place in the arid west are conditions so favorable 

 for economic irrigation by pumping as in California. 



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