The dredging of the upper Hudson River, phase one of which began in May, is wrapping up this month, and while the federal Superfund project proved complex and costly, regulators agree the results are mainly positive.

The dredged PCB waste is condensed into a filter cake, which is then shipped to Texas for permanent disposal.Phase two, which is slated to begin in 2011, could push the total project price tag to upwards of $700 million, and whether the General Electric Company will pay for that leg of the cleanup is yet unknown.

Why did GE foot the initial bill? Two of its plants (Hudson Falls and Fort Edward) funneled some 1.3 million pounds of polychlorinated biphenyls (PCBs) into the Hudson from 1947 until 1977 or so (when the likely carcinogen was banned). A 1973 dam removal sped up the flow of contaminated water downstream, and decades of debate followed on how to handle the toxic mess.

So far, 10 of the 18 targeted Hudson River  PCB "hot spots," have been dredged, with more than 240,000 cubic yards of contaminated river bottom being excavated. But with phase one of the cleanup efforts winding down, it is unclear whether the remaining eight areas will see any action before phase two begins.

Due to the enormity of the project, it is being carried out in stages, and unexpectedly high levels of PCBs and particularly debris-laden sediment found during the first phase have slowed the cleanup schedule.