As a conservative Republican and friend of the Bush administration, Sen. Jake Garn (Utah) is all for cutting the budget. But not when it comes to the Central Utah Project.

The same lawmaker who wants to cut programs such as welfare and veterans benefits said he was "absolutely shocked" last month when the Bush administration voiced its opposition to a bill authorizing $679 million to finish the project, a huge water system serving Salt Lake City and surrounding areas.

So he arranged a meeting with Dennis B. Underwood, commissioner of the Interior Department's Bureau of Reclamation, and pointedly mentioned the administration's proposed deficit-reduction plan. "If I can support your {proposal}," Garn said he told Underwood, "then you can support this."

Garn said he was not making a threat -- "I don't work that way" -- but that was the effect. Afraid of angering a staunch ally in the budget battle, administration officials dropped their opposition to the bill.

Congress has many sacred cows, but few are harder to corral than federal water projects. Lawmakers from western and southern states have long made a priority of costly flood-control, irrigation and storage schemes, and the current budget crisis hasn't changed that tradition.

The energy and water appropriations bill that emerged last week from a House-Senate conference keeps funding for water programs at roughly the same level as last year, providing about $4.2 billion to the Army Corps of Engineers and the Reclamation Bureau. Lawmakers resisted administration pleas to confine spending to existing projects, moving ahead with more than a dozen new ones.

Other bills would authorize a variety of new water expenditures, among them the new ceiling on the Central Utah Project.

"What's amazing is that notwithstanding the terrible budget crisis, there's . . . a wide-ranging array" of new undertakings, said Edward Dickey, the Corps' acting principal deputy assistant secretary for civil works. "The reality is that once you start a project, it's very rarely not finished."

In many respects, of course, the era of huge federal water projects is over. The West's mightiest rivers have been dammed, the Mississippi's floods brought to heel, the largest irrigation projects completed or nearly so. And while many water projects have acquired richly deserved reputations as costly boondoggles, environmental disasters, or both, more recent projects have tended to avoid the excesses of the past.

A 1986 law requiring significant cost-sharing with local governments has forced states and cities to take a harder look at projects they once got for free. Congress also has started to funnel money toward environmental improvements, such as new marshes for waterfowl, and the current package of water bills continues that trend.

Indeed, because Garn's Utah bill includes significant funds aimed at encouraging water conservation and protecting streams and rivers, environmentalists have dropped their traditional antipathy toward the project. "It's a very responsible bill," said David Conrad, a water resources specialist with the National Wildlife Federation.

Garn said he has tried to keep costs down on the project, but that he has little choice but to pursue it. "Unfortunately, Utah is the second most arid state in the country," he said. "So {water} is the lifeblood of the state."

The huge network of tunnels, aqueducts and reservoirs siphons water out of the Colorado River basin, then diverts it through the Wasatch Range and into populated areas of central Utah, where it can be tapped by farmers, ranchers, cities and industry. Begun in the 1950s, the system, when complete, will allow Utah to claim its full share of the Colorado River under an agreement with other western states.

"Otherwise, it flows downhill to California and we can't use it," Garn said.

In some ways, water projects are no different from other varieties of congressional pork, which can range from military bases to university grants to highway "demonstration" projects. Each has its own constituency and political rewards.

But water projects occupy a special niche. For one thing, they can be fabulously expensive, requiring years of appropriations; the Central Utah Project eventually will cost about $2.2 billion. For another, their chief benefits often accrue to powerful, moneyed interests that can be crucial to a lawmaker's political longevity, such as farmers and ranchers.

The near-universal appeal of such projects has turned them into a kind of political currency; members trade votes for projects in other districts in exchange for support of projects in theirs. It helps that the key water and public works committees tend to be controlled by lawmakers from the South and West, traditional bastions of flood control and irrigation.

This year's water program could still be influenced by budget maneuvering now underway. In the meantime, proposals before Congress include:The Lake Andes-Wagner project. Situated in South Dakota, this $200 million project would tap the Missouri River to irrigate 45,000 acres belonging to 173 farmers. That works out to more than $1 million per farm, a cost that the administration says is too high.

Environmentalists have raised alarms about the presence of selenium, a natural element toxic to wildlife and waterfowl, which they fear could contaminate streams and marshes if the land is irrigated.

The project's sponsors have addressed that concern, but not in the way that critics would like. In the authorization bill that cleared the Senate Energy and Natural Resources Committee last month, the project's initial stage is established as a "demonstration" aimed at studying selenium contamination. "There are plenty of opportunities to research this problem without creating a new one," said Edward R. Osann, water resources director at the wildlife federation.

An aide to Sen. Thomas A. Daschle (D-S.D.), the project's leading sponsor, said the research program is a "unique opportunity" to study selenium, and noted that the rest of the project cannot be built if it proves a threat to the environment.

Wallisville Reservoir. House-Senate conferees have approved spending $9.2 million as part of a $100 million project to dam the Trinity River in Texas, creating a reservoir that would provide water to Houston. But according to a memo from the Office of Management and Budget, the project would destroy 5,000 acres of wetlands, "including over 3,000 acres of virgin cypress swamps," and "starve the Galveston Bay of the nutrient-rich freshwater flows that feed this nationally significant estuary."

Island Park Dam. Last month, Sen. James A. McClure (R-Idaho) secured an amendment providing $1 million to the developer of a private hydroelectric power plant at the Island Park Dam on the Henry's Fork of the Snake River. The money would compensate the company for losing a tax credit that it would have earned had it completed the plant by 1988. A McClure spokesman said the break was justified because the company missed the deadline not through any fault of its own, but due to unusually strict environmental constraints.