President Carter's first big fight with Congress this year was over water. One of next year's may be, too.

Barely a month after his inauguration, Carter announced he would strike from the federal budget 18 dams, river channelization and irrigation projects, thus saving taxpayers $5.1 billion. The "hit list" exploded into months of acrimonious confrontation with Congress, during which the President was called arbitrary, illogical and naive.

Naive or not, Carter is again wading into pork-barrel politics - this time with a basic reappraisal of the way billions of dollars in water projects are approved and funded.

Instead of trying to knock off one by one what he considers congressional boondoggles - a strategy that had limited success - Carter has ordered his aides to draft recommendations by February for "comprehensive reform of water resources policy."

The new water policy, as Carter and his advisers have broadly outlined it over the last few months, will be an effort to reverse the historic tide of massive structural waterworks, providing billions of dollars in federal subsidies for selected areas and economic interests.

"I personally believe that we have built enough dams in this country and will be extremely reluctant as President to build any more," Carter said in the 1976 New Hampshire primary. Now he is getting ready to make good on that premise with a far-reaching administrative and legislative program.

In so doing, he would challenge, in the words of one legislator, "the political virility" of Congress, as well as alienate a host of special interests, including Western politicians and farmers, construction companies and barge operators.

The coming fight has broad regional implications since a disproportionate amount of water project funds is spent in the West. As Sen. Daniel Patrick Moynihan (D-N.Y.) put it last spring, "The great American desert has been turned green by a flow of funds from the Northeast."

Although more than 100 officials in a dozen agencies are busily compiling options papers, some observers question whether the President can afford a water battle so soon after the energy fight.

"It's political dynamite and next year is an election year," said one high-level Interior Department official.

Others, however, say Carter has gone too far to turn back. Next spring, as in the past, Congress will try to load the public works bill with water projects. Carter must choose between renewed confrontation or giving in - and possibly losing face.

The new policy would affect all future water projects, including 600 congressionally authorized, but as yet unfunded, projects planned by the Army Corps of Engineers and Interior's Bureau of Reclamation. These would cost more than $13 billion. Carter also could challenge the $33.6 billion it would cost to complete projects now in the construction or land acquisition phase.

While the recommendations could be more or less tough, interviews with a dozen participants indicate the policy is likely to include measures:

To increase the interest rate used to calculate costs and benefits, thus making projects harder to justify:

To impose uniform cost-sharing formulas on construction agencies and increase local, state and private contributions:

To prevent water pollution, destruction of wildlife areas and rich farmland, and

To favor nonstructural solutions, such as funding a flood plain park instead of channelizing a river, or imposing conservation measures instead of building a new reservoir.

Such changes would amount to a revolution in water policy, challenging the historic American faith in technology as the answer to all water problems from floods to shortages.

The assumptions of the Carter administration are environmentalist: perhaps rivers were made to flood, and deserts not to bloom. Perhaps man should accommodate himself to nature, and not vice versa.

"The drought in the West and recent severe flooding in the East have shown us that despite the massive numbers of federally funded water projects in existence, we are still as susceptible as ever to the ravages of the weather," Carter said last spring.

"Instead of proceeding down the same road of more and bigger structural projects, we need to rethink our policies."

The federal government has built water projects since 1824, when the young republic enlisted the Corps of Engineers to construct navigational canals and waterways to promote interstate commerce at a time of few roads and no railways.

In 1902, the Reclamation Act was passed to help win the West by encouraging settlements around irrigation projects in 17 Western states. The Dust Bowl, floods and the Depression of the '30s led to the formation of the Soil Conservation Service, the Tennessee Valley Authority and the expansion of the corps to undertake flood control.

Dams, canals and reservoirs brought substantial benefits - electricity, jobs, flood control, irrigated farmland - and provided imposing monuments for their political sponsors. But today the best dam sites are taken. Flood control projects have encouraged development along rivers, thus increasing runoff and flood damage. And the western Sun Belt has undergone a population explosion encouraged by false expectations of sufficient water.

Many of today's projects are "blatant boondoggles," said Charles Warren, chairman of the Council on Environmental Quality. He cited the $612 million Garrison Diversion in North Dakota, which critics say, would flood 220,000 acres of farms to irrigate 250,000 acres, as well as pollute three rivers and damage eight wildlife refuges.

The Westlands irrigation project in California will cost taxpayers $769 million in subsidies for such farmers as Standard Oil of California and Southern Pacific, the Interior Department calculates. Channelizing a Louisiana river will cost $20 million just for the benefit of two oil rig companies, Carter has said.

Such projects, vigorously defended in Congress, are possible because "we have no national policy for billions of dollars in federal expenditures," said Kathy Fletcher, a Domestic Council aide. "We just spend it."

Twenty-five federal agencies spend $10 billion a year on water programs in "a jumble of inconsistent, conflicting practices that subsidize uneconomic, inefficient and wasteful confusion," Warren said.

"For example, five departments are involved in flood-control or navigation projects that have eliminated several million acres of productive farming and forest land and destroyed fisheries in hundreds of miles of rivers. At the same time, other agencies are spending money to protect farm and timber land and create fisheries."

Many projects would be unjustified if a higher interest rate were used in cost-benefit analysis. Congress applies a 3.25 per cent rate to projects authorized before 1969 - a grandfather clause Carter would abolish. "Even though we are building the projects today, we are pretending that the cost of capital is still the same as it was many years ago," he said. The rate was boosted to 6.37 per cent in 1974. Carter aides are considering 10 per cent.

New water policy could establish uniform criteria for approving projects. "The corps and the Bureau of Reclamation calculate costs and benefits completely differently, so you can't compare their projects," Fletcher said.

Cost-sharing formulas are chaotic, with cities and states "shopping for the best deal . . . in a supermarket for federal programs," Warren said. A flood-control project from the Small Business Administration costs a city 47 per cent in local funds, but the same project can be had for 17 per cent from the corps, he said.

On the whole, "the beneficiaries of federal water projects do not bear a fair share of the enormous capital and operating costs," Carter says. "An example is that the users of the nation's waterways pay nothing for their construction and maintenance."

At a 90 per cent federal subsidy, the corps built a $4 billion, 25,000-mile network of canals and harbors, maintaining it with $100 million a year. But barge owners have always succeeded in killing any bills that would charge users of waterways.

The Reclamation Bureau put up 100 per cent of the money to build irrigation projects. "If states had to pay 20 per cent, would they spend their own money?" asks Assistant Interior Secretary Guy Martin. "A lot of people think not."

Rep. George Miller (D-Calif.) questions the "bizarre federal policy" of providing "large amounts of subsidized water to a farmer in an arid region to grow a water-intensive crop like rice or cotton, when we pay farmers in [water-rich] areas not to grow them."

One controversial option under study would give states block grants based on population, thus drastically altering regional disparities. Under the current system of congressionally designated projects, 40 per cent of funds go to three Western river basins.

"We need a system to assure that the most needy projects are built, not the projects of your favorite senator," Martin said. "The rules we've played by in the past are not acceptable."

Reform will be difficult, however, as congressional committees jealously guard their slivers of the public works pie. Different committees control funding and procedures of various agencies. Cost-sharing reform - and the coordination it implies - will be "a gut fight," one House veteran predicts.