RIVER;
New York City hopes to open part of its new sewage treatment plant on the Upper West Side a year ahead of schedule but to abandon construction of some or all of the rest, reducing the treatment of matter going into the Hudson River. City officials said yesterday that under a revised agreement being negotiated with the Reagan Administration, the first section of the plant could open by June 1986 and remove 25 to 35 percent of the biological matter from the sewage. The plant was originally designed to remove 85 percent. The city is hoping to abandon its plans to build more than the first section to save an estimated $250 million. The plant will serve the West Side of Manhattan. Untreated sewage from this area is now pouring into the river at the rate of 150 million gallons a day. The city says the reduction in treatment would not be enough to harm the river, but some environmental groups said yesterday that they would oppose scaling back the plant.
