President Ronald Reagan is an extraordinarily lucky man. William D. Ruckelshaus, the man who took Sen. Edmund Muskie's bill and turned it into the Environmental Protection Agency, has agreed to give up a good job in private industry to return to what is going to be the roughest job in Washington. This is the same William D. Ruckelshaus who is part of the moderate faction of the Republican party, the faction the Reagan administration has systematically tried to cut out of power.

In persuading Ruckelshaus to take over EPA again, the White House had virtually nothing to offer. The conversations leading up to his acceptance of the nomination would have been priceless to hear.

Senior White House aide: "Look, Bill, I know we've had our differences, and I know that there were times when we thought you were too moderate for the initiatives we had in mind. No doubt you noticed that you were not nominated to the president's cabinet. But we needed team players, fellows who understood what the president wanted to do. Well, some people misunderstood. We, huh, we need your help, Bill. There's, uh, quite a mess, here."

What has happened at EPA is an object lesson in how not to run a government agency, and it is also an object lesson is what is fundamentally wrong with the Reagan administration. The true believers came to Washington talking about the Reagan Revolution and they set out on a course that showed they meant that literally. They proposed radical changes in social, economic, environmental, educational, defense and foreign policies. There were holy wars to be fought on innumerable fronts. What they forgot was that Americans aren't into holy wars, and that Americans favor moderation in their leaders and consensus in their government.

What Americans got, instead, was an administration short on experience and long on ideology, and a president who is fond of referring to his opponents as radicals and extremists. Yet he staffed agency after agency with ideologues who have no better credentials for governing than early and abiding loyalty to Ronald Reagan. Prospective appointees were subject to political litmus tests. Moderates, such as Ruckelshaus, and Democrats need not apply.

The politics of alienation, of them against us, flourished at EPA with the kind of behavior that invites odious comparisons to Watergate: There were hit lists of people who were politically unacceptable, documents were shredded, and government officials manipulated public funds for blatantly political purposes. We are now discovering that Rita Lavelle, the Superfund queen, not only dined on the tab of the industries she was regulating but found time to mix politics with Superfund money in a meeting with White House aide Jim Medas.

Unfortunately for the two of them, Lavelle brought her assistant, Susan Baldyga, who took some devastating notes on the conversation. While Lavelle was supposed to be cleaning up hazardous waste sites that present imminent dangers to human health, yesterday's installment of the EPA scandal found her deciding with Medas where the Superfund money would be spent to create "political hay."

Like the Watergate scandal, what happened at EPA is unraveling daily in the newspapers, complete with people forgetting meetings and conversations and suddenly, when the heat is on, remembering them. And like Watergate, what we are seeing here, at best, is an extreme form of the worst in American politics, a form marked by a lack of decency and sense of fair play, an obsession with political power and a disregard for the public interest. But unlike Watergate, the dirty tricks contemplated with Superfund money involve not only the integrity of political institutions, but the health of countless private citizens as well.

There is no one the president could have chosen who has a better shot at cleaning up EPA. Ruckelshaus, father of three children in expensive colleges and two in private school, is doing this at considerable personal cost. Bobbie Greene Kilberg, a White House fellow in the Ford administration and a friend of Ruckelshaus, says he is doing it out of a "deep sense of public service."

As such, he may bring to the Reagan administration a quality that goes far beyond what he will do at EPA. He will serve as an example of someone who understands that moderation is a virtue in government and that public service is not the place for holy wars.