TO DELIVER steady supplies of water to California and other western users, including farmers, the federal government over the years has built an elaborate network of dams (creating storage areas) and aqueducts or canals. As a general proposition, farmers have not been called upon to pay their full share of the cost of these facilities. The government provides them with the water they need for irrigation at a loss -- at taxpayer expense. Now some California farmers are proposing to resell part of their subsidized water to other users -- the Metropolitan Water District of Southern California, which serves Los Angeles -- at a substantial profit. The question is whether they have -- and should have -- the right to do this.

A surprising cross-section of interested parties agree that to some extent they should. The rgument against letting them do it is the obvious one of unfairness. The farmers would be enriching themselves from water provided them at public cost, not so it could be resold, but supposedly because it was needed for the great public purposes of developing the western lands and American agriculture. They would also be selling something not quite theirs to sell, less an asset than an excess benefice, much as was done in the now discredited practice of selling surplus tax write-offs, in so-called tax leasing.

The arguments on the other side have mainly to do with practical alternatives. The farmers have historic and contractual rights to the water. They have a surplus -- they waste a lot of water under the present system -- and Los Angeles faces a water deficit. The cost to Los Angeles consumers and conceivably federal taxpayers as well will be greater if they have to acquire water by some other means -- through new dams and aqueducts, for example. These further public works would likely have a high environmental price as well. The resale plan would represent a constructive shift toward greater conservation of existing sources of the natural resource now perhaps in shortest supply in the West. It might also help establish a partial market system for allocating water generally, a system that would be run by price instead of clout. There is a similar movement toward making beneficiaries bear the true cost of water in the water projects authorization bills now pending in Congress.

There needs to be a new water economy in the West, and moves such as these deserve to be encouraged. But there should also be a limit to the profits of farmers and other present water-holders who may benefit from a transition from a low-price system to a high. Some work is under way in both the Interior Department and Congress on what would amount to new rules. Water is rapidly becoming a national as well as vital regional issue. Policy is turning, and needs to be bothclosely watched and carefully framed.