Tokyo Electric Power Co. began dumping water tainted with low levels of radioactivity into the Pacific Ocean on Monday night so that a central waste facility could be used to store more dangerously radioactive water, officials said.

The company, which operates the Fukushima Daiichi nuclear plant that was crippled in the March 11 earthquake-tsunami disaster, said it could release up to 11,500 tons of radioactive water into the sea. The water had collected in the waste facility and a drainage pit, officials said.

“We are causing trouble and inconvenience to the local people, but to have to force on them further hardship we are extremely sorry,” said a Tepco official who spoke to reporters in Fukushima, trying to hold back tears.

A spokeswoman for Japan’s Nuclear and Industrial Safety Agency said the less-contaminated water must be disposed of so that workers can secure a place to store more highly contaminated water on the site. Otherwise, there is a possibility of danger to emergency crews.

On Sunday, Japanese government officials said the Daiichi plant may continue to release dangerous radiation into the air for several months.

Tepco’s reputation has suffered in the wake of the nuclear crisis. On Tuesday, its stock fell by the maximum daily limit; shares fell by 80 yen or 18 percent, according to the Associated Press. In total, Tepco’s share price is down 80 percent since the earthquake hit.