In March 2011, an earthquake and tsunami resulted in a nuclear disaster at the Fukushima Daiichi nuclear power plant which contaminated the groundwater with radioactive materials. This water has been collected, treated, and stored onsite since 2011.

Since 2021, the Tokyo Electric Power Company (TEPCO) has been preparing the infrastructure for the "safe" release of Fukushima's treated water through a process called the Advanced Liquid Processing System (ALPS). The Japanese government has approved the plan but various stakeholders raised alarm about its impact not just in Japan but also in the Pacific region.

On August 24, Japan started discharging treated water amid lingering concern about the damage it may cause. TEPCO explained the process of releasing the water which will take place over the next three decades:

During the initial stages of sea discharge, a very small amount will be carefully discharged using a two-step process.

Firstly, as Stage 1 of the initial discharge of ALPS treated water, today, a very small amount of ALPS treated water will be diluted with seawater and stored in the vertical discharge shaft (upstream water tank) in order to verify that ALPS treated water is being diluted as planned. After this stored water has been sampled and tritium concentrations measured, we will move on to Stage 2, continuous discharge into the sea on and after August 24.