AS CONGRESS struggled to remove $30 billion from this year's federal budget, it had to do some pretty drastic surgery. But as reporter Howie Kurtz documented in his "Pork Barrel Politics" series this week, after a brief encounter with tough- minded belt-tightening, congressmen's favorite do- it-for-yourself projects emerged unscathed.

Water projects--canals, ports, dams, river diversions--are the classic examples of programs that endure long after their justification dies. Although waterways once yielded great benefits in moving goods where there was no other route, huge projects are now based on rationales so flimsy that, when the cost-benefit ratios don't work, supporters blithely reverse the proposed direction of traffic, rewrite their arguments and push ahead without missing a beat (Tennessee-Tombigbee Waterway). Irrigation projects that once helped to open the West now flood as much productive farmland as they would irrigate (Garrison Diversion Project). Dams costing nearly $50 million are planned to control occasional flooding for towns of 1,500 (Willow Creek).

Water projects are not alone. Buildings are a particular favorite, especially if a congressman's name is affixed. A nice example is the federal courthouse named for former congressman Harold T. (Bizz) Johnson in Redding, Calif.,--where there is no federal judge. If absolutely no other reason can be found to save an obvious loser, it can always be argued that continuing will avoid wasting the money that has already been spent.

Highways are visible evidence of a congressman's legislative prowess, but they're becoming old hat. These days the fashionable boondoggles are energy projects. Of these, the Clinch River Breeder Reactor is champion. Designed to demonstrate an obsolete technology that will be positively medieval by the middle of the next century, when breeders might become competitive, CRBR has already cost $2 billion and construction has not yet begun. A synthetic fuels plant called SRC I has Clinch River beat in a few respects, however. Its cost overrun rate has been faster (900 percent since 1977), its cost is greater (about $4.5 billion), and industry's share of the "partnership" is lower (2 percent). Everything's all right, though, because some of the profits from the sale of the synthetic fuel will go to the government. They will, that is, if buyers can be found for fuel costing the equivalent of $76 per barrel of oil.

Isn't it comforting to know that no matter how many economic revolutions come and go, some things never change?