Washington — By 1936, North Dakota farmers desperately needed water. For three years in a row, drought had shriveled their wheat into broom straw and parched their pocketbooks - while in the western part of the state the Missouri River, untapped, gushed south toward the Mississippi River and the sea. North Dakota begged the federal government for money to divert Missouri River water into thirsty fields. The funds didn't come. Before the dry years ended, four-fifths of the state's farmers lost their farms.
The great drought of the Great Depression is but a dim memory now, and in summer North Dakota's fields are golden seas of wheat raised by dry-land farming techniques. But the state is still fighting for a Missouri River irrigation project - the Garrison Diversion.
Garrison, a complex web of canals, dams, and lakes, was first authorized by Congress in 1965. Today, the project is only 15 percent complete, and faced with stiffening opposition in Congress its future is far from secure.
''The logic in this program was lost long ago,'' says a congressional staffer who studies public works programs. ''It insults ducks, fish, and Canadians.''
''The main question is do we have our fair share of the water?'' retorts Sen. Quentin Burdick (D) of North Dakota. ''(Missouri) water is our right. They can't take that away from us.''
Traditionally, Congress loves to play with water. Long ago, legislators discovered that federal water projects - dams, canals, levees - are fun to dispense, since such construction is highly visible and easy to take credit for.
Not all these projects make sense from a national point of view. Political scientists consider many water projects classic examples of the ''pork barrel'' spending process, in which members of Congress push programs that benefit their constituents, but don't make economic sense from a national point of view. But affected legislators insist that critics of water projects don't understand the importance of water to many states.
Garrison thus symbolizes a debate that swirls around many water projects. Whatever its merits, the Garrison Diversion would amount to man altering nature on a grand scale. Water would be pumped from the Missouri River near the town of Garrison, in northwest North Dakota, and diverted to the center and east of the state through 3,000 miles of reservoirs, canals, pipelines, and drains. If completed as planned, Garrison would irrigate 250,000 acres of farmland, while occupying 220,000 acres itself.
But the US House of Representatives last year voted to cut off the project's funds; only concerted arm-twisting by North Dakota's senators convinced a House-Senate conference committee to keep Garrison alive. The Interior Department's Bureau of Reclamation now plans to build the project in phases. Construction won't progress beyond Phase I, about one-third of the project, before sensitive environmental problems are solved, a bureau official says.
''I don't think we'll get the extensive project we once hoped for,'' admits an aide to a member of the North Dakota congressional delegation.
Cost is one obstacle. Congress originally thought the project would cost $207 million. But inflation and lawsuit-induced delays have helped push its projected price to $1.1 billion.
Theoretically, the US Treasury would get this billion dollars back sometime next century. Most of the money would come from a fee on hydroelectric power generated by Missouri River basin dams. Users of Garrison water would pay back only 2 percent of the project cost.
''Garrison is fundamental pork barrel,'' insists Sen. Gordon Humphrey (R) of New Hampshire, a member of a water resources subcommittee. ''It benefits a few people at the expense of many.''
Irrigation, of course, is Garrison's primary reason for existence. But only 0 .6 percent of North Dakota's agricultural land would be irrigated by the project. Back in 1965, the Bureau of Reclamation figured Garrison would produce 1.3 to 1 - and even this calculation may be too rosy, since it assumes interest rates will hover around 3 percent.
''This whole program is only marginally justifiable on an economic basis,'' says an aide to Rep. Silvio Conte (R) of Massachusetts, ranking Republican on the Appropriations Committee and one of Garrison's most vocal critics.
North Dakotans, in reply, say Washington owes them a water project. In the 1940s the federal government dammed the Missouri River near the town of Garrison , to prevent flooding in states downstream. Five hundred and fifty thousand acres of rich North Dakota farmland were suddenly at the bottom of the brand-new Lake Sakakawea.
In return, North Dakota was promised a 1-million-acre water diversion project , state politicians say. Garrison, say North Dakotans, is thus but partial payment for the loss of some of the state's best farmland.
''Look at the sacrifice we've made by being denied the economic production from that bottomland. We've lost $35 million a year in net personal income,'' says former North Dakota Gov. William Guy, citing a state economic study.
But ''out-of-state opposition,'' Mr. Guy mutters, has stalled Garrison. This opposition, led by the National Audubon Society, took legal action that halted work on Garrison for five years, until a federal court dismissed its lawsuit last May. Its objections are focused on the project's possible environmental effects.
''Garrison would do as much environmental damage as any water project in the US today,'' says Brent Blackwelder of the Environmental Policy Center.
Consider ducks - an easy thing to do in North Dakota, since the state is home to more ducks than any other part of the US, except Alaska. Garrison's canals would be laid smack through a ''prairie pothole'' region, where shallow lakes, sloughs, and marshes provide a waterfowl's version of ideal real estate. Sixty thousand acres of wetlands would be destroyed, estimates the US Fish and Wildlife Service, with another 13,000 acres damaged. A dozen national wildlife refuges would be adversely affected.
Garrison's supporters complain that environmental objections are overblown. ''The environmentalists don't really like any water project,'' grouses an aide to Sen. Mark Andrews (R) of North Dakota.
But the project's possible environmental effects have also riled the Canadian government. As now designed, Garrison would connect the Missouri River with the Hudson Bay Drainage Basin, and the Canadians are worried this new link will introduce pollutants and ''rough'' fish such as carp into their waters, killing off more valuable species. The International Joint Commission, a US-Canadian advisory group that monitors water resources shared by the two countries, found in 1976 that Garrison might reduce the commercial fish population of Manitoba by half.
Opposed by Canadians, US environmentalists, and conservative budget-watch groups such as the National Taxpayers Union, Garrison owes its continued existence to the power and persuasiveness of North Dakota's two senators.
Senators Andrews and Burdick are on the Appropriations Committee, a powerful rostrum from which to persuade other senators to vote for the North Dakota water project. Andrews, as chairman of the Appropriations subcommittee on transportation, is in a particularly good position.
''Andrews carries a lot of weight, especially considering he's a first-term senator. Everybody depends on him for their state's transportation projects,'' says a House Appropriations staff member.
The Reagan administration's fiscal 1984 budget proposes to spend $22.3 million on Garrison. The House will likely vote to stop this money, the project's critics claim, setting up another showdown with the Senate over Garrison's future.
''North Dakota should be looking at a cheaper, more sensible proposal,'' perhaps using pipelines instead of canals, says the Environmental Policy Center's Mr. Blackwelder.
Several North Dakota newspapers have also called for another look at the project. But something must happen relatively soon if North Dakota is to get a Missouri River diversion in any form. The Missouri is one of the few Western rivers with water that isn't divided up by an interstate compact - and there are thirsty, growing states downstream.