Chiba Prefecture's Ichihara City expanded the area covered by its Level 5 emergency safety advisory on Monday, September 21, 2026, because of the possibility that the Takataki Dam could carry out an emergency release, according to ウェザーニュース. Level 5 is the top rung on Japan's five-step warning scale.
The same day, flooding information at the highest level was issued for rivers in two Chiba cities. 日テレNEWS NNN reported a Level 5 inundation notice for the Takasaki River, which runs through Sakura City, warning that overflow may already have occurred. NHK reported inundation information for the Yoro River in Ichihara City at 21:40, and ｄメニューニュース also reported Level 5 inundation notices for rivers in both Sakura and Ichihara.
Separately, 日テレNEWS NNN reported that authorities were moving toward holding off on the Takataki Dam emergency discharge.
The reports, carried by several Japanese outlets, describe a broad emergency response across Chiba Prefecture rather than a single incident. An emergency release from a dam sends a surge of water downstream, which is why the advisory in Ichihara was widened before any discharge was confirmed.
What to watch next: whether the Takataki Dam release is formally cancelled or carried out, and how conditions on the Takasaki and Yoro rivers develop.