A one-ton tank of chlorine sprung a leak at a Cambridge water filtering plant yesterday, releasing a pool of highly corrosive liquid into the surrounding area and forcing a smallscale evacuation of the area around Fresh Pond Reservoir.

Two workers in the plant were sent to the emergency room at Mt. Auburn Hospital for minor respiratory problems resulting from the leak, officials at the scene said. But a team of 43 Cambridge firefighters managed to contain the leak shortly after noon.

Fire Capt. Gerald Reardon said that no serious damage resulted from the chlorine spill. "A cloud vaporizes very quickly in the air," he said. "There was no danger to the water."

Nonetheless, officials on the scene said that spill could have been extremely dangerous if it had not been contained so quickly.

"It had the capacity for a serious accident," said Sgt. Frank Burns of the Cambridge police.

Reardon identified the two hospitalized men as James Babcock and William Zebal, both employees of the Water Department. Both were released from Mt. Auburn Hospital yesterday afternoon, a hospital official said. Neither could be reached for comment yesterday.

Acting Lt. Robert Currier of the Fire Department had also been hospitalized during the incident for an "irregular heartbeat," Reardon said.

Fire officials received a call about the spill at 10:52 a.m., after city water officials found themselves unable to handle the problem alone, Reardon said. He said a defective valve in a full chlorine tank being placed into service caused the leak.

Although Reardon said that the Fire Department had not ordered the evacuation of the surrounding park, several persons exiting the area said that police officers had told them to leave.

Metropolitan District Commission Police cordoned off the area shortly after the leak broke out, barring all public access to the area. Burns said that the area was still too dangerous to allow the public to enter.