Trumpets and drum rolls, please. That all-time congressional favorite, the biennial flood control and water resources bill, is marching across Capitol Hill again.

Work is not completed, but this year's edition of the traditional "pork barrel" construction of locks and dams, harbors and levees seems likely to end up bigger, costlier and more ingenious than ever.

As an added fillip, the proposed public works policy changes that President Carter has been urging on Congress since 1977 to save both scarce western water and federal funds are mostly ignored in the basic bills.

The administration calls the bills -- reported out by the House Public Works Committee, still pending in the counterpart committee in the Senate -- "a serious step backward" and generally "unacceptable." But whether the president would go so far as to veto a big public works bill in this kind of political year is uncertain.

As for environmental groups, they see only trouble ahead. Ed Osann of the National Wildlife Federation says of the Senate bill, "They are totally ignoring the position of the administration -- it is given no credence. The underlying reality is that the subcommittee is determined to pacify as many senators as possible."

Brent Blackwelder of the Environmental Policy Center says the House bill would aid so many congressional districts -- about 100 at last count -- that it is virtually defeat-proof. "It is as bad as any omnibus bill I've ever seen," he says.

The bills are modifications of legislation that failed of passage in the last hours of 95th Congress late last year. The House has added more projects to its 1978 version; the Senate appears headed that way.

Carter has pleaded with Congress to conserve water and money partly by requiring states to share water projects costs -- a deterrent of sorts -- and by requiring projects to meet higher cost-benefit and environmental standards than often in the past.

But in many ways, both House and Senate bills go in the opposite direction -- approving projects without favorable benefit-cost ratios or without Army Corps of Engineers approval, using federal money to provide local water-supply systems, skirting laws protecting fish and wildlife, waiving local cost-sharing requirements.

Some examples:

At the urging of West Virginia and Kentucky legislators, the bill direct construction of flood control structures on the flood-prone Tug Fork River along the two states' border, even though the corps says the cost -- perhaps as much as $700 million -- cannot be justified.

The districts of the two top House water subcommittee members, Chairman Ray Roberts (D-Tex.) and ranking Republican William Harsha of Ohio, would be awarded precedent-setting water supply systems paid for with federal funds.

A new $29 million Parker Lake in Okalahoma and a $3.14 million drainage project at Bushley Bayou in Louisiana are authorized in the House bill although required fish and wildlife protection studies have not been done.

Several dozen bridge and road replacements, bridge construction and harbor-dredging projects -- each with a congressional patron -- are approved with a waiver of the usual requirement that local governments share in the cost.

Even the Corps of Engineers, usually an eager ally, has raised an eyebrow at committee proposals to authorize projects that have not been thoroughly studied for cost or effectiveness.

The Army says the House committee bill would cost $4.1 billion, but the Congressional Budget Office says it is so sweeping and so vague that an accurate cost estimate cannot be made.

Environmental lobbyist Blackwelder describes the bills as "Profiles in Pork." Blackwelder said, "These committees just do not take the administration seriously. There is no reflection of administration policy positions. Far from responding with corrective action and reform, they have put in a one-house veto over corps activities and created more projects of the type that have drawn such criticism in the past."

But the popularity of the something-for-everyone approach in the House bill is reflected in the committee's final report. Only one committee member Rep. Robert W. Edgar (D-Pa.), a regular critic of water policy based on politics, voted against the bill.