BUREAU OF PUBLIC ROADS. 415 



or prospective, whose plans, lielcl in abeyance during the war, sought 

 immediate execution at its close. Irrigation enterprises of this 

 class, including in all many hundreds of thousands of acres, com- 

 prised besides new projects several of long and fairly prosperous 

 history. High values of farm produce gave much encouragement 

 to such enterprises to improve their structure, revise their organi- 

 zations, and conserve their water supplies, to the end that a more 

 economical distribution of water might be effected and the area served 

 in the past materially extended. Thus, in Idaho alone, project's 

 are now in various stages of promotion which, if carried out as now 

 planned, will increase the irrigated area of the State by 1,500,000 

 acres; half as much as is now irrigated. 



Notwithstanding the i*apid development of this work, standard in- 

 vestigations of duty of water, pumping, flow of water in various 

 types of conduits, and efficiency of appliances and equipment used 

 in irrigation, which had either been temporarily discontinued or 

 reduced in scope during the war, were resumed. Technical re- 

 ix)rts on flow of water in concrete pipes and spillways for reservoirs 

 and canals were completed and await publication. An extensive 

 field examination to determine the efficiency of typical reservoirs 

 in Cache la Poudre Valley, Colo., begun in 1917, was brought to a 

 conclusion. Meanwhile the investigation of flow of water was ex- 

 tended to metal pipes, a survey of effective types of chutes, drops, 

 and other canal structures, begun prior to the war, was resumed, and 

 a final rejx)rt was prepared on three-years' experiments to determine 

 the proper time and amount of irrigations in the vicinity of Twin 

 Falls, Idaho. Laboratory experiments, which sought to ascertain 

 the movement of moisture from a free-water surface in various soils, 

 were finished and the results assembled in a report whicli awaits 

 publication. Studies of the capillaiy movement of moisture be- 

 tween soils of different moisture content were resumed. These in- 

 vestigations arc being supplemented by similar studies in irrigated 

 fields, lands provided with artificial drainage, and soils which should 

 be drained. 



High cost of iron and steel has greatly widened the field and en- 

 larged the demand for concrete pipe to meet rigid conditions in 

 irrigation systems, notably wiiere pressure pipe is needed for the 

 conveyance of water under high heads. California alone now has 

 more than 150 concrete pipe manufacturers, and concrete pipe is 

 being installed at the rate of many hundred miles a year. A need 

 foi* the standardization of methods of manufacture and the develop- 

 ment of standard tests and testing equipment to determine the 

 strengths of pipes of different makes has resulted in the establish- 

 ment of a field laboratory where such equipment Avill be devised 

 and tests conducted. Field tests, meanwhile, have been made to 

 determine the tensile strength, resistance to internal pressure, and 

 perviousness of 40 kinds of concrete pipe now in use in irrigation. 



Other w^ork demanded by after-war conditions has included a 

 study of new devices to reduce labor in the distribution and appli- 

 cation of w^^ter, initiation of experiments to determine the extent 

 of seepage losses from canals, ancl the extending^ of first-hand assist- 

 ance to communities seeking the development of imderground water 

 for irrigation. High prices and curtailment of sales of pumping 



