THE FIRST BIG legislative debate of the 1980s, scheduled to begin on the floor of the House today, does not concern anything like Iran, say, or Soviet-American relations or inflation. No, it concerns (what else?) more than 175 water projects and numerous other provisions lumped together in the authorization bill for the Corps of Engineers. The good old Corps.

These projects range from a $579 million power-house on the Columbia River in Oregon through a $2.6 million flood-control along the Schuylkill River in Pennsylvania to a $300,000 marina on Lake Texoma in Texas and Oklahoma. Some, no doubt should be built. Others are just logrolling. In some instances, the bill goes so far as to declare that benefits from a particular project exceed costs despite studies by the Engineers that say the opposite.

The message sent by the Committee on Public Works and Transportation when it approved this awful bill last fall was that nothing has changed on Capitol Hill. Despite efforts of theCarter administration, environmental groups, some members of Congress, and even the Engineers themselves to inject some planning and common sense into the biennial rivers and harbors debate, this bill is little more than just another collection of boondoggles.

It also would create some terrible precedents -- for example, authorizations for the Corps to build, at no cost to the local governments, nine local water distribution systems. (Two of the nine, it will be noted, are located in the district represented by the ranking Republican on the committee, Rep. William H. Harsha, and another is in the district of the Democratic chairman of the subcommittee that handled the bill, Rep. Ray Roberts.) The Department of the Army says these nine projects will cost $174 million, unadjusted for inflation, and the precedent created could get the government into spending "tens of billions of dollars" on projects that have been traditionally a "prerogative and responsibility of local governments."

There are many more things wrong with this legislation. It alters other cost-sharing requirements on water projects so that the federal government pays more and local governmentds less. It authorizes projects without completed feasibility studies. It waives cost-effectiveness requirements when they stand in the way of politically favored projects.

The administration has almost, but not quite, said President Carter would veto the bill if it clears Congress in anything remotely resembling its present form. He should. Even better, the bill should not clear the House in its present form. It is so bad, so out of keeping with needs of the country and the constraints on the economy in the 1980s, that it should be sent back to the committee with a straightforward message that times have changed, whether the pork-barrelers in Congress have noticed it or not.