BECAUSE Congress keeps putting aside the more controversial appropriations bills, a long list of dubious projects -- and worse -- are getting a free ride. They are getting a steady flow of federal money through the continuing resolutions that shield them from the normal process of challenge and correction. Currently, the prime example is the energy and water appropriation.

It's the bill that contains the money for the Clinch River breeder reactor, for which the construction site is now being cleared in Tennessee. This enormously expensive project is intended to bring plutonium into the civilian economy, and a lot of congressmen would like a chance for another vote on that one. They won't get it this year.

The bill also carries the money for the Garrison Diversion Project, an irrigation project in North Dakota that appears to violate this country's boundary-water treaty with Canada. The Canadians protest, vehemently, that it will drain water loaded with pesticides and herbicides into the Hudson Bay watershed. While the cost of this project has soared, the reasons for irrigating the land have become increasingly shaky. Not everybody who thinks it's a bum idea is Canadian. But there won't be a vote on that appropriation in the House this year.

The Tennessee-Tombigbee Waterway is also in the bill -- $1.3 billion spent on it already. Who knows how much more to go? Like the Pyramid of Cheops, its scale is impressive but its practical usefulness is open to question. The last time it came to the floor, last year, the House came within 10 votes of killing it. Needless to say, its advocates and defenders are not eager to have another roll call on it this year.

The Democratic leadership calculated that the floor debates on this appropriation might consume several days. Since the House wants to go home for Christmas, that seemed too much. As the leadership pointed out, the end of the session is a bad time to bring up a bill like this. But the bill was first reported last September, and apparently that was a bad time as well. For Clinch River, Garrison and the Tenn-Tom, there is no good time for debate and a vote. That's why they will all go rolling along into the new year on a continuing resolution -- which will doubtless come to the floor under a closed rule, preventing unfriendly amendments.

Continuing resolutions are habit-forming. As Congress slides into the practice of letting more and more of the budget ride along on these resolutions, rather than the more rigorous process of appropriations legislation, some members evidently begin to see a certain advantage in it. The continuing resolution, passed with little debate and no changes, becomes a device to protect another kind of endangered species -- the hugely expensive public construction project, for which the original economic rationale has faded.