Twenty years ago, Washingtonians considered the Potomac River a broad, slow-flowing garbage dump. The only houseboats on the waterfront were aquatic tenements tied up at quaintly named Buzzards' Point.
Today, the cleaned-up river is becoming as gentrified as Georgetown. Many young professionals are moving into boats docked in the Washington Channel, mere blocks from Capitol Hill and federal office buildings.
This new life on Washington's waterfront illustrates a point overshadowed recently by concerns about toxic wastes: In the last decade, much progress has been made in the fight against pollution of lakes, rivers, and streams in the United States.
We have the Clean Water Act to thank for much of this gain. Congress, currently considering changes in the act, must decide how to proceed in the struggle to purify US waters.
The US is still a long way from reaching the Clean Water Act's most ambitious goal: elimination, by 1985, of all pollution discharges into navigable waters.
But salmon have reappeared in New England's Connecticut and Penobscot Rivers. The aging of Lakes Ontario and Erie has been slowed. Stream pollution, as measured by the US Geological Survey, has stayed even over the past seven years. Overall, 21 of 33 states responding to an Environmental Protection Agency survey reported generally improving water quality.
We are ''holding our own,'' in terms of water quality, concludes a Conservation Foundation report. This is a ''noteworthy accomplishment,'' the report says, considering gross national product has risen 40 percent since 1970, and no serious attempt has yet been made to control ''nonpoint'' water pollution.
Cleansing nonpoint pollution - the runoff from farms, construction sites, and city streets - is the major unresolved clean-water issue. Dubbed nonpoint because it doesn't flow from a single, easily controllable source, this runoff accounts for up to half of all water pollution, according to environmentalists. But its pervasive nature makes it difficult and expensive to eliminate. US agencies have puzzled over the question for more than a decade.
Now, Congress is taking yet another crack at settling the nonpoint pollution issue, as it tries to update and reauthorize the Clean Water Act. (The act expired last fall, and its programs are continuing on a stopgap basis.)
Environmentalists are pushing for mandatory control of nonpoint runoff. In the Senate, which is forging ahead of the House on Clean Water reauthorization, Sen. David Durenberger (R) of Minnesota has proposed a $150 million program to meet such strict requirements.
But affected interest groups - farmers, in particular - complain that mandatory controls would be a very expensive leap in the dark.
''We favor a $25 million demonstration project'' to study the problem further , says Bruce Hawley, assistant director of the American Farm Bureau Federation.
The Senate Environment Committee is scheduled to meet Tuesday and settle the question. A staff member says it's unlikely that controls as far reaching and expensive as the Durenberger proposal will be adopted.
The fact that Congress is likely to take some sort of action against the elusive enemy - nonpoint runoff - is, however, an indication of how political winds have shifted.
Last year, environmentalists were frustrated in their efforts to push a Clean Water reauthorization to their liking. This year, a rewrite that pleases them, for the most part, is sailing through the Senate. The Environment Committee has completed work on all but the nonpoint portion of the legislation.
''It's a very good bill,'' says Sharon Newsome of the National Wildlife Federation.
Environmental groups are happy, for instance, that a provision to ease industry waste treatment requirements has been eliminated from the new Clean Water Act. They like a part of the bill that calls for regulation of municipal sewage sludge.
But the new Clean Water Act could still be substantially reshaped on the Senate floor. And the House is waiting to move until it sees the Senate's finished product.