Sludge is a big problem in Washington. The city's Blue Plains sewage treatment plant does a great job of keeping the Potomac clean - but in the process, it produces 1,400 tons of organic sludge a day. Nobody knows what to do with that much waste, especially since a plan to ship it to South America fell through.
Solving one environmental problem often just creates another. The district's sludge overload shows how tackling water, land, or air pollution separately can simply shift pollutants around, instead of getting rid of them.
This dilemma is leading many environmental experts to conclude that the United States must think less about ''air pollution'' or ''water pollution,'' and more about pollution as a whole.
''We're in a new stage, where we have to consider the total problem,'' says J. Clarence Davies, vice-president of the Conservation Foundation.
Taking a unified approach to pollution fighting is not a brand new idea. When the Environmental Protection Agency was formed in 1970, it was supposed to gather all US environmental control programs into a coordinated strike force.
But the historic pollution laws of the '70s - the clean air and water acts, and others - each addressed only one part of the environment. The EPA in effect was balkanized, with divisions pursuing separate goals.
''What our laws have done is divide the environment up into little boxes,'' complains David Sarokin, a project director for Inform, an environmental research firm based in New York.
This splintering, coupled with the sheer difficulty of cleaning the environment, has created problems. A US Steel plant near Pittsburgh, to conform with new water regulations, stopped dumping coal tar and other impurities into the Monongahela River. Months later, the EPA discovered that the air pollution caused by the company's new disposal process was an even worse hazard.
In Philadelphia, a recent EPA study says, one of the dirtiest air polluters is the local water treatment plant.
Today, both EPA officials and outside experts are paying more and more attention to ''integrated'' pollution control. It is not so much the mistakes of the past that concern them as the problems of the future.
For one thing, most of the relatively easy pollution cleanup has been accomplished. Environmental decisions to come - what to do about acid rain, how to clean up hazardous waste - are going to be difficult and involve lots of money. There will be little margin for error.
''Clearly, we must get the biggest cleanup bang for the pollution-control buck that we can,'' says Dan Beardsley, head of the EPA's integrated environmental management program.
Toxic chemicals will be particularly hard to mop up with anything but an integrated approach. Toxics move easily through the environment, leaching from dumps into ground water and settling from polluted water into sewage sludge. Many are dangerous even in small amounts and are very persistent. ''We should have adopted (integrated pollution cleanup) a long time ago,'' says Blair Bower, a consultant to Resources for the Future, a Washington-based environmental group.
Exactly what more unified pollution fighting might entail, however, is a matter of some debate.
At the EPA, it means setting regulatory priorities. The agency's integrated management program, now four years old, thoroughly examines the pollution habits of individual industries (such as steel or iron) and geographic areas (a $1.5 million study of Philadelphia has just been completed). It tries to figure out how these companies and cities can maximize their pollution-control dollars.
Officials in the integrated program decided, for instance, that the steel industry was being forced to use at least one technique - air controls on oxygen furnaces - that cost much more than it was worth, relative to other cleansing methods.
But to some environmental groups, ''integrated pollution control'' means something more extensive. It might mean reshuffling the troops at EPA to eliminate arbitrary divisions into air, water, and hazardous-waste departments. It might mean redrawing many environmental laws, so officials don't have to act on them separately.
''One thing we're looking at is a unified environmental statute,'' says Mr. Davies of the Conservation Foundation, which is researching the issue.