On one hand, the success is apparent: America's environmental movement is riding high. Its Big Three - the National Wildlife Federation, the National Audubon Society, and the Sierra Club - boast nearly 5 million members. Together with the smaller organizations in their wake, they have notched up recent victories on the reauthorization of the Endangered Species Act and the new barrier-islands protective legislation. The Wildlife Federation alone - the largest direct mailer in the nation - will send out 70 million pieces of mail this year. Bright-eyed and aggressive, this is clearly a lobby to be reckoned with.
On the other hand comes puzzling news from several recent polls. In a Newsweek/Gallup survey Feb. 27, potential voters ranked ''the environment'' at the very bottom of 11 issues in the presidential campaign. On a similar USA Today poll, it wasn't even cited as a significant issue.
What does it all mean? Why do environmental concerns rank so low? Is the green lobby asleep in the woods of apathy?
That last question has, it seems, at least three answers:
* No. Jay D. Hair, executive vice-president of the Wildlife Federation, is delighted. The very mention of the issue in such polls shows, he says, that ''the environmental movement has arrived'' at last. The ranking doesn't worry him: ''The idea now,'' he says, is to ''keep it moving up.''
* Yes. Audubon Society president Russell W. Peterson finds the polls ''very disturbing.'' Why? Because he sees them as evidence of a public ''myopia'' that focuses too much on the present and too little on the future. ''People don't see the urgency of (protecting the environment),'' he laments.
* Irrelevant question. William A. Turnage, executive director of the Wilderness Society, remains convinced that the environment ranks just behind the economy and foreign policy as a major issue in the campaign. Those 11 issues reported by Gallup? Six, he says, are actually matters of domestic economy. Three others are foreign policy concerns. Otherwise, the issues are education and the environment.
However you view the polls, two things seem clear. First, the ground has shifted underneath the greens this past year. Second, it may shift even more as the election approaches.
The Reagan administration, moving to mollify its critics, has helped with the shift - replacing James G. Watt with Judge William P. Clark as interior secretary, and replacing Anne Gorsuch Burford with William G. Ruckelshaus as administrator of the Environmental Protection Agency (EPA). Strong criticism remains - about acid rain in the East, land-use questions in the West, and toxic waste and drinking-water quality nationwide.But the Wildlife Federation's Dr. Hair gives ''extremely high marks'' to Mr. Ruckelshaus, noting that he has restored confidence to the agency, made more than a dozen good top-level appointments, and moved forward on ''extremely tough issues'' like acid rain, EDB, and the proposed ban on leaded gasoline.
Audubon's Mr. Peterson, however, sees the appointments of Mr. Ruckelshaus and Judge Clark simply as palliatives. Under the popular Mr. Ruckelshaus, he says, ''the country is relaxing.'' In fact, Mr. Peterson says, the shift ''hasn't changed a thing,'' because EPA proposals still get blocked by the White House and the Office of Management and Budget. A telling measure may be the agency's operating budget of $1.114 billion - well below the $1.35 billion it enjoyed when Mr. Reagan took office, despite expanded policing duties.
On one thing many environmentalists agree: This administration has an anti-environmental record. And that, says Mr. Turnage, makes Mr. Reagan vulnerable to attack by either Walter Mondale or Gary Hart, both of whom are well thought of among environmentalists.
Result: the environment may still become a major campaign issue. If Mr. Reagan retains the image of strong leadership, if the economy remains on the mend, and if things remain manageable overseas, then his major vulnerability just may be the environment. And the campaign, despite what winter polls say, may green up considerably by summer.