IWAKI, Japan — The overpowering earthquake and tsunami that ripped through northern Japan in March 2011 took so much from Tatsuo Niitsuma, a commercial fisherman in this coastal city in Fukushima Prefecture.
The tsunami pulverized his fishing boat. It demolished his home. Most devastating of all, it took the life of his daughter.
Now, nearly nine years after the disaster, Mr. Niitsuma, 77, is at risk of losing even more — his entire livelihood — as the government considers releasing tainted water from a nuclear power plant destroyed by the tsunami’s waves.
Prime Minister Shinzo Abe’s cabinet and the Tokyo Electric Power Company — the operator of the Fukushima Daiichi plant, where a triple meltdown led to the worst nuclear crisis since Chernobyl — must decide what to do with more than one million tons of contaminated water stored in about 1,000 giant tanks on the plant site.
On Monday, Japan’s Ministry of Economy, Trade and Industry proposed gradually releasing the water into the ocean or allowing it to evaporate, saying a controlled discharge into the sea would “stably dilute and disperse” it. The ministry ruled out alternatives to releasing the water like continuing to store it in tanks or injecting it deep into the ground.
The water gets pumped through the reactors to cool melted fuel that is still too hot and radioactive to remove. For years, the power company, known as Tepco, said that treatment of the water — which involves sending it through a powerful filtration system to remove most radioactive material — was making it safe to release.
But it is actually more radioactive than the authorities have previously publicized. Officials say that it will be treated again, and that it will then be safe for release.
Regardless of government assurances, if the water is discharged into the sea, it will most likely destroy the livelihoods of hundreds of fishermen like Mr. Niitsuma. Consumers are already worried about the safety of Fukushima seafood, and dumping the water would compound the fears.
It would “kill the industry and take away the life of the boats,” he said. “The fish won’t sell.”
With Fukushima preparing to host baseball games during the Summer Olympics next year, and the plant running out of land on which to build storage tanks, the debate has taken on a sense of urgency.
Until last year, Tepco indicated that with the vast majority of the water, all but one type of radioactive material — tritium, an isotope of hydrogen that experts say poses a relatively low risk to human health — had been removed to levels deemed safe for discharge under Japanese government standards.
But last summer, the power company acknowledged that only about a fifth of the stored water had been effectively treated.
Last month, the Ministry of Economy, Trade and Industry briefed reporters and diplomats about the water stored in Fukushima. More than three-quarters of it, the ministry said, still contains radioactive material other than tritium — and at higher levels than the government considers safe for human health.
The authorities say that in the early years of processing the deluge of water flowing through the reactors, Tepco did not change filters in the decontamination system frequently enough. The company said it would re-treat the water to filter out the bulk of the nuclear particles, making it safe to release into the ocean.
Some experts and local residents say it is difficult to trust such assurances.
“The government and Tepco were hiding the fact that the water was still contaminated,” said Kazuyoshi Satoh, a member of the city assembly in Iwaki.
“Because next year is the Tokyo Olympics, Prime Minister Shinzo Abe wants to present the image that everything is ‘under control,’” said Mr. Satoh, referring to a speech by the Japanese leader to the International Olympic Committee when Tokyo was bidding to host the 2020 Games.
The power company acknowledged that it had not made it easy for the public to get information. The water treatment data “has not been presented in a manner that is easy to understand,” said Ryounosuke Takanori, a Tepco spokesman.
“As long as the water was stored in the tanks, we thought it didn’t matter whether the water” exceeded safety standards for discharge, said Junichi Matsumoto, a general manager in the Fukushima Daiichi decontamination and decommissioning office.
Mr. Niitsuma, for whom fishing is not just a livelihood but also a balm against grief over the loss of his daughter, said he thought both Tepco and the government needed to come clean.
“I want them to see the reality squarely and disclose information fully,” said Mr. Niitsuma, who goes out alone on his two-ton boat at dawn three times a week.
His wife, Yoko, waits on the pier. On a recent morning, she helped drag the nets out of the boat and dump squirming octopus, flounder and a few red gurnard into buckets that the couple loaded onto a small flatbed truck to drive to a warehouse where wholesalers bid on the fish.
Mrs. Niitsuma said she didn’t believe the government was looking out for Fukushima’s fishing families. “They are talking about discharging the water,” she said. “That itself means they are not thinking about us.”
The question of whether the water could be decontaminated to safe levels is a matter of degree, scientists say.
If the water is processed so that the only radioactive materials that remain are low levels of tritium, said Kazuya Idemitsu, a professor of nuclear engineering at Kyushu University, releasing it into the ocean would be “the best solution in terms of cost and safety.”
Mr. Idemitsu added that functioning nuclear plants around the world release diluted water containing tritium into the ocean.
Some scientists said they would need proof before believing that the Fukushima water was treated to safe levels.
“I want to see the numbers after they’ve removed these additional radionuclides,” said Ken Buesseler, a senior scientist in marine chemistry and geochemistry at Woods Hole Oceanographic Institution in Massachusetts. “Then, and only then, can I make a judgment on the quality of the rationale for releasing it or the consequences of releasing it.”
Government officials argue that the water is not so much a scientific problem as a perceptual one.
“If the water is discharged into the ocean, the price of seafood products may drop, or consumers won’t want to buy them at all,” said Shuji Okuda, director for decommissioning and contaminated water management at the economy and trade ministry. “So even though there is no scientific evidence that the water is dangerous, we are worried about the effects.”
More than 20 countries still have import restrictions on Japanese seafood and other agricultural products that were imposed after the 2011 disaster. Earlier this year, the European Union lifted its ban on some products.
In Fukushima, the fishing industry brings only about 15 percent of its pre-disaster catch levels to market. Every haul is sampled and screened in labs run by Fukushima’s prefectural government and the fisheries cooperative.
According to the co-op, the central government currently prohibits the sale of only one species, a rare type of skate.
Tadaaki Sawada, the co-op’s division chief, said that if the water was discharged, buyers would be unlikely to believe government safety assurances.
“Most people can live without fully understanding the details of radioactivity,” Mr. Sawada said. “They can just say ‘because I don’t understand fully, I won’t buy Fukushima fish.’”
In the prefecture, where thousands of residents never returned after evacuating, those who have come back harbor lingering doubts.
“In the corner of my mind, I wonder if it is safe or not,” Keiko Nagayama, 65, said as she browsed at a seafood freezer in Naraha, a hamlet in the original 12-mile exclusion zone around the Fukushima plant.
A government evacuation order was lifted in 2015. Although flounder and Pacific saury from Iwaki were on sale, Ms. Nagayama chose flounder from Hokkaido, in far northern Japan.
Yukiei Matsumoto, Naraha’s mayor, declined to offer an opinion on the idea of water disposal from the nuclear plant.
“Nuclear policy is central government policy,” Mr. Matsumoto said. “The contaminated water is their business.”
Naraha is one of several Fukushima towns where the central government has spent heavily to draw people back to their communities.
Just 3,877 people — a little over half of the original population — have returned. Tokyo has devoted large sums to subsidize a new school, a strip mall and a new arena that cost 4 billion yen, or about $37 million.
On a recent afternoon, a smattering of people worked out in the gym, while just one man used the 25-meter swimming pool in the arena complex.
Yukari Nakamura, 33, a local artist, had been hired to paint murals on the walls and windows. Her husband, Yuuki, and two young children were the only family in a spacious playroom.
Ms. Nakamura said a Fukushima label on fish gave her pause. “My heart aches to reject the seafood, and I feel such pain not being able to recommend it,” she said, tearing up. “I don’t want to hurt the fishermen who caught it, but it is so complicated.”