Chesapeake pollution can be reversed

Chesapeake Bay - one of the world's largest, most productive estuaries - is in trouble. Submerged vegetation and many animal species are declining. Fish and crab catches have dropped. The amount of oxygen-depleted, ''dead'' water has increased.

However, these alarming trends may be reversed, as the Environmental Protection Agency's Chesapeake Bay program moves from research to action.

Green Jones, who has directed the EPA program, says he is optimistic that the bay can recover. He explains that it is not dead. It is deteriorating, just as Lake Erie was deteriorating, partly because of pollution. Efforts to save Lake Erie helped it recover. So, Jones says, ''I don't think there's any question that it (the quality of the bay) can be enhanced.''

EPA's program involves a coordinated effort by Chesapeake Bay states - Delaware, Maryland, Pennsylvania, and Virginia plus the District of Columbia. Its research phase, which ended last September, has confirmed the impressions of residents and fishermen that the bay has deteriorated.

For example, Robert J. Orth and Kenneth A. Moore of Virginia's Institute of Marine Science have found a significant reduction in all species of submerged vegetation in all sections of the bay during the last 15 to 20 years. In a report in Science last Oct. 7, they call the decline ''unprecedented in the bay's recorded history.'' They say their findings indicate ''that this estuarine system has been undergoing an environmental stress of major proportions.''

This stress is also reflected in the bay's water quality. There is a natural cycle in which some deep water in the bay loses much of its dissolved oxygen. However, the part of the bay that is affected by this anoxia has grown tenfold since the early 1950s, according to research reported in Science Jan. 6. The research team linked the growth of the ''dead'' water area with declines of many animal species, including oysters, clams, crabs.

The bay ecology is a complex living web. There is no one cause of the stress it is undergoing. However, the runoff of nitrogen fertilizer from farms does appear to be a major factor. Jay L. Taft of the Harvard University Herbaria and a member of the anoxia study team says this is the first kind of pollution to control. He explains that the added nutrients from this runoff stimulate biological activity beyond what is normal or healthy for the bay as a whole. This contributes to the oxygen depletion.

Robert Orth also cites fertilizer pollution as a major cause of the vegetation decline, especially in the northern part of the bay. The added nutrients encourage blooms of algae and growth of organisms that live on the plants themselves. Both factors reduce the light reaching the plants and inhibit their photosynthesis. Increased sediment running off into the water has a similar effect.

Orth emphasizes that the bay's problem is complex. The decline of vegetation is not due to any single factor. There was concern that herbicides might be to blame. However, the study he made with Kenneth Moore shows this is not the case, although herbicides may be acting in some unknown way in concert with other factors. Likewise, fertilizer runoff is not the only pollution source. But it does seem to be the most important factor to try to control at this point.

Taft says that this finding encourages optimism. For one thing, bay ecologists now have some scientifically credible data to back up the impressions of deterioration which fishermen and other bay users have noted. Second, he says , ''having gotten some of the dimensions of the problem scientifically, one is in a better position to begin to do something about it.''

Exactly what that ''something'' should be now is being defined. The EPA has $ 4.25 million in its present budget to continue its bay program. It will be used, in part, to set up a liaison office in Annapolis. This office will maintain a data center, monitor the bay, make computer studies of the bay system, and encourage public participation in pollution control efforts. Meanwhile, at this writing, the Council of Bay Area States was due to meet Jan. 25 to set out ground rules for action.

Green Jones explains that the strategy will be to try to work through education rather than regulation. Since the first target is to cut down fertilizer runoff, he hopes farmers can be persuaded that it is in their best interest to both control pollution and save money by keeping expensive fertilizer on the land. EPA plans no regulatory program for farmers.

Also, Jones explains, improving the bay will be a continuing effort. At base, it is population growth in the basin which is causing the problem. The impact of people has to be accommodated.

Jones says he can project that the bay would be in very bad shape by the year 2000 if nothing were done to prevent deterioration. But he adds that mathematical simulations show that farmers can both increase productivity and reduce pollution. Thus he says he is ''optimistic that the population impact can be accommodated.''