Environment Agency officers found very low oxygen in the moat at Kirby Muxloe Castle in Leicestershire on 30 August after reports of distressed fish. The agency and Kirby Muxloe 87 fishing club pumped oxygen for about two weeks; levels improved and pumping ended last week.
English Heritage said it is monitoring the moat with the fishing club. It said the Environment Agency suggested hot weather followed by thunderstorms may have contributed to the low oxygen. The agency says warm water holds less oxygen, while intense summer storms can wash pollutants from nearby land into watercourses, further reducing levels.
