HEN Eighty-first Congress passed a bill raising 160-acre water limitation to 480 acres on San Luis Valley, Colorado, project, President Truman vetoed it and asked his temporary Water Resources Policy Commission to examine problem of making exceptions to 160-acre water limitation in particular cases. When commission undertakes this assignment, it may find it neither possible nor desirable to halt its inquiries into limitation at this point. For 160acre limitation, as solicitor of Interior Department has said, is the heart of reclamation law, not a mere appendage to it.1 The limitation embodies nation's high policy on land and water resources, and maintenance of its integrity-not merely question whether, in a particular instance, proper acreage figure is 80, 160, or 480-is at stake. The 160-acre water limitation is device that was enacted by Congress in 1902 to extend historic American land policy to water in arid and semi-arid west. The policy, stemming from Pre-emption Act of 1841 and Homestead Act of 1862, was designed to distribute benefits of public domain widely, by favoring actual settlers against monopolists and speculators of that day. In 1902, when Congress was persuaded that public treasury ought to help develop western irrigation, it limited water rights for private landholding beneficiaries to an amount adequate for no more than 160 acres of each holding. Congress regarded such a limitation necessary to justify spending public funds for private benefit. Without limitation, Congress was unwilling to extend public assistance to reclamation of private lands.2 When lands to be irrigated were publicly owned, these were to be distributed subject to homestead laws in tracts of not less than 40 nor more than 160 acres . . 3 The benefits to private landowners under reclamation law are substantial. The value of waiving interest charges to private irrigation beneficiaries is alone equivalent to more than half cost of a project.4 The Bureau of Reclamation has given Congress additional figures indicating, on Central Valley Project in California, that average Class I water