When I was EPA administrator, an agency scientist brought me the test results on a major midwestern city's water supply. The tests revealed the presence, in trace amounts, of over 700 chemicals. I asked whether the water was safe to drink. To paraphrase his response, "We don't know that the water is unsafe to drink, but we can't say that it is safe either."

He explained his careful answer: because the science of determining health and environmental effects of the thousands of chemicals common in today's society was (and is) in its infancy, a definitive answer was a long way off. Particularly notable was his cautionary observation that there was no quick way to learn. Tests had not yet been devised to forecast accurately the latent or long-term effects of exposure to most environmental contaminants. Moreover, EPA had to decide whether investment in expensive and potentially fallible technology would be a prudent and affordable insurance policy: some protection against our ignorance on the larger scientific question of whether the water was safe to drink.

I cite this anecdote principally to illustrate what people familiar with environmental issues know: most EPA decisions are "judgment calls." In almost no case is the scientific evidence free of ambiguity. In our complex industrial economy, the environmental unknowns are greater than the knowns. All of EPA's decisions have significant economic consequences, as well as public benefits. What EPA must do is to weigh these costs and benefits--bringing to bear the best scientific knowledge that can be assembled--and make judgments that are informed by a toughness of mind, a commitment to getting the job done and a passion for objectivity and fairness.

Somehow during its first 10 years, amid all the controversy over specific issues, EPA maintained remarkable credibility in making the difficult judgments delegated to it. While Congress, the states, the public, industry and the press may at times have disagreed with individual decisions, I believe they perceived that the agency was conscientiously pursuing the public interest.

During that decade, three consecutive administrators, two Republican and one Democratic, ran this process in as non-partisan, non-political fashion as they could. All three enjoyed strong bipartisan support in Congress, and the agency remained remarkably free from even the scent of scandal or special privilege. In short, it was a credible agency. That may soon no longer be the case.

Without credibility, EPA cannot moderate legitimate differences in search of consensus. The result is a stalemate, where no one trusts the other fellow's facts or motives, and no one believes the EPA can be trusted to produce an objective set of facts.

Ultimately, credibility depends on both the perception and the reality that the administration is conscientiously looking at all sides of an issue to come up with the best decision. At present, neither Congress nor the public has confidence that this is happening. Regrettably, this problem runs right to the president himself. President Reagan gave scant indication in his 1980 campaign that he understood the complexity of environmental issues, and there is scant evidence that his views have since evolved. He correctly cautioned in his recent press conference that accusations are not proof of wrongdoing. But the appearance of wrongdoing can have the same chilling effect.

How then can the erosion of EPA's credibility be stopped?

Much urgent environmental business awaits this Congress and the executive branch. The Clean Air Act, the Clean Water Act, the Resource Conservation and Recovery Act, the Safe Drinking Water Act and the Toxic Substance Control Act are all up for reauthorization. The burden on the legislative branch will be all the heavier now that EPA is hampered in its historical advisory role of the expert broker moderating honest differences.

In the days immediately ahead, Congress itself can take a responsible lead as it exercises its oversight function. In an atmosphere already poisoned by allegations of misconduct, extraordinary care will be needed to avoid lending substance to claims of opportunism. Truth does not necessarily lie with those who blow either horns or whistles. In the long run, the facts are basically friendly; carefully gathered, they will speak loudly for themselves.

After the initial containment efforts, the natural course for the administration will be to hunker down. After all, any organism under fire does this for self-protection. But experience argues that, in the long run (that is, the next two years, rather than two months), it is better to open up than to close up. This may require the president to strengthen the management of the agency (as he suggested in his press conference) or appoint an oversight team (perhaps including previous Republican presidential environmental appointees and respected representatives of industry and environmental organizations) or re-examine his administration's perceived anti-environmental tilt. Whatever corrective measures are chosen, the administration needs to give clear signals that it intends to carry out the government's environmental responsibilities fairly, competently and openly.

Finally, the civil servants who staff the agency are undergoing a particularly discouraging, even humiliating, trial. For more than a decade, they have provided the professionalism, competence and integrity that have been the agency's backbone. More than ever, those qualities will now be put to the test; more than ever, they are needed. For the agency professionals, the only viable road is to "stay their course."

The long-term issues are important enough, and there are enough people who care deeply-- inside and outside the government, inside and outside Washington--that all parties drawn into this sad drama must unite to end it. If not, the growing public perception of political bankruptcy may require at least a public trustee to administer public resources. The normal alternative in bankruptcy, liquidation of the existing structure, is not really an option.