A map of proposed water projects in Thursday's editions incorrectly placed the Bonneville Lock and Dam near Vancouver, British Columbia, instead of Vancouver, Wash.

Forty miles east of Portland, Ore., sits the mighty Bonneville Lock and Dam, regulating the flow of water traffic on the Columbia River.

Bonneville has become even mightier in recent days, for it was a key element in the standoff between Congress and the White House over a crucial spending bill needed to fund the federal government for the next year.

Sen. Mark O. Hatfield (R-Ore.), the chairman of the Senate Appropriations Committee, attached $177 million for a new Bonneville lock to the huge spending bill when it came through his committee.

Dozens of other House and Senate members saw the same opening for long-delayed pet projects -- Congress hasn't passed a major water project bill since 1976 -- and had similar responses. In a relatively clear display of preelection pork barrel politics, legislators added a total of more than $6 billion to the spending measure.

President Reagan threatened to veto the bill unless all the water projects were stripped from it, and last night the House-Senate conferees reluctantly went along.

Reagan has opposed full federal funding of most water projects and has tried unsuccessfully to get Congress to force local and state governments and water project users to pay more for construction of water projects, such as harbors and inland waterways.

Environmentalists, who have opposed the adminstration on most issues, sided strongly with Reagan on this one, saying barge owners and others in the shipping industry, who benefit from the costly water projects, should foot the bill, not the general public. They say cost-sharing would weed out unnecessary projects.

But "for some members, particulary in the West, water is more valuable than gold or silver," said House Majority Leader James C. Wright Jr. (D-Tex.). "They can make the case that water projects pay for themselves economically."

Said one Democratic staffer, "it's a big hit for everybody right before an election. It's the proof of the power of the incumbency."

As a White House veto loomed, House Democratic leaders agreed to drop the water projects. But Hatfield, head of the Senate conferees, balked. He denied that the issue was the Bonneville lock and dam, but a question of whether Congress would allow itself to be dictated to by the White House on appropriations matters.

But last night, Hatfield, under pressure by colleagues anxious to return home to campaign, relented.

Nearly 60 water projects were stripped from the bill, touching nearly every state and most members of the House and Senate Appropriations Committees.

On the House side, according to figures put together by the Office of Management and Budget and environmental groups, Rep. Wes Watkins (D-Okla.), an appropriations committee member, sought $52 million to create a lake to supply water in his district.

Rep. Louis Stokes (D-Ohio), an appropriations member, wanted $6 million for Cleveland's harbor. Reps. Vic Fazio (D-Calif.), also on appropriations, and Robert T. Matsui (D-Calif.) tried to get $123 million in the spending measure to deepen the channel leading to Sacramento.