If all the pollutants in the Hudson were dissolved in its water and no more were getting in, the river would clean itself within several weeks merely by flowing out into the Atlantic Ocean. But the worst contaminants, PCBs (polychlorinated biphenyls) trapped below the river bottom, are not so simply disposed of.

A huge amount, 1.3 million pounds, of this persistent pollutant that was discharged into the Hudson from the 1940s until 1977 by the General Electric Company from its plants at Hudson Falls and Fort Edward are most heavily concentrated along a 20-mile stretch between Fort Edward and Troy. Manufacturing and discharges of PCBs ceased when it became known that they were carcinogenic, but the damage had already been done. Despite several costly attempts to eliminate the PCB problem, it still plagues us - inasmuch as, except for shad which lives most of its life out in the ocean but returns annually to the river briefly to breed, commercial fishing in the Hudson is still banned and is likely to remain so for at least a century or more.

Synthetic PCBs are oily liquids that may turn out to be as durable as natural crystals found in rocks. They latch on to river-bottom mud particles that get buried temporarily by deposited sediments, which were eroded upstream, but they enter the food chain through being consumed by burrowing organisms feeding on detritus. These in turn are eaten by other river animals and are dispersed in small but harmful amounts throughout the entire aqueous habitat. The PCB-laden particles also get exposed and picked up to be moved several feet downstream by storm or snow-melted waters before being deposited and covered again. At this rate, it will take a long time for the PCBs to reach the ocean where they would be dispersed.

Dredging and disposal on land areas near the river failed because the PCBs soon leaked back into the Hudson. Burial in distant authorized landfills was not undertaken because of the large mud volumes involved. Now, tunnels are being dug 200 feet below the river bottom in an attempt to ascertain whether the Hudson's burden and fishermen's economic losses can be reduced if PCBs can be interred there. But even so, the EPA announced earlier this year that it may take as much as 100 years before commercial fishing can be allowed to resume. Attempts to remove all the PCBs will fail, and it will take much longer for the Hudson to cleanse itself. Moreover the overall problem with toxic SOCs (synthetic organic compounds) has multiplied since dozens of SOCs have shown up now in both finfish and shellfish and they will have to be dealt with as well.

Back in the 1970s, the Corps of Engineers was planning to spend what today would be tens of billions of dollars in its so-called Hudson River Project to bring water from dozens of miles upstream, down to New York City and to Nassau County. The long 1963-67 drought had almost dried up the city's upstate reservoirs and lowered Nassau's aquifer water tables as well. The water would have been fresh but PCB pollution would have made it undrinkable, and the technology to remove it had not been developed then. The project was stopped after it was revealed that that the Corps had ignored the PCB problem and aside from that had quietly made Nassau responsible for the entire cost of the work. Conservation, however, saved the day.