SENATE PASSAGE, at long last, of an Alaska lands bill is a significant step toward final resolution of what is rightly called the conservation issue of the century. Sens. Tsongas, Jackson, Roth and Hatfield, who negotiated the compromise with seemingly infinite patience, deserve warm praise for their achievement. But the Senate Bill not good enough -- it still needs to go back to the House for some critical improvements.

Several senators, however, are claiming that this is the Senate's absolute final word on the subject -- a take-it-or-leave-it proposition for the House. Given the press of business in the closing days of the session -- never mind tht the Senate consciously scheduled the bill for consideration now -- there will be those who are tempted to accept the Senate version or frightened into accepting it by the prospect of another filibuster. The House shouldn't yield to either sentiment. The Senate bill needs improving.

There is, of course, far more at stake here than parliamentary prerogatives. The Senate bill bends too much to development concerns and excludes certain key areas that should have wilderness protection. The opening up of the Douglas Arctic Wildlife Refuge to oil and gas exploration is one example. More than 95 percent of the state's suspected oil reserves lie outside this magnificent area, and these should logically be explored and developed first. A wilderness designation is not irreversibile; development in a fragile wilderness usually is. Other areas in southeast Alaska, the Tongass National Forest Wilderness and the Gates of the Arctic National Park, that are protected in the House bill are opened to timber or mining or transportation development in the Senate version -- a bad idea. The Senate bill sets a mandatory quota of timber to be logged each decade regardless of whether it turns out that the forests can sustain that yield, setting a poor precedent for national forest management everywhere.

The House bill, which passed by an overwhelming margin last year, struck a fair balance between the country's interest in preserving its last and greatest wild frontier, the right of Alaskans to control a substantial part of their own state and the national need for some of Alaska's vast oil, mineral and timber resources. But there is still time and room to reach a compromise that would be acdeptable to both houses. Rep. Udall, the House leader on Alaska, put it about right: "We have worked too long and too hard for the spirit of though but reasonable compromise to desert us now. There is no reason not to play the ninth inning just because the first eight have been so hard."