The Chess Valley is partly within the [[Chiltern Hills]] [[Area of Outstanding Natural Beauty]] (AONB), with wildlife characteristic of chalk streams and chiltern hills. It supports several key species listed in the Government's UK Biodiversity Action Plan. [[Mammals]] such as the [[European Water Vole|water vole]], [[birds]] including the [[green sandpiper]], [[grey heron]], [[grey wagtail]], [[little egret]], [[osprey]], [[mute swan]], [[stonechat]], [[water rail]] and [[kingfisher]], [[flora]] such as [[water crowfoot]], [[purple loosestrife]], [[hemp agrimony]], [[water forget-me not]] and [[Sparganium erectum|branched bur-reed]]. [[Freshwater fish]], found include specifically the [[brown trout]], [[Thymallus thymallus|grayling]] and [[European bullhead|bullhead]]. To support the fish population there is a rich diversity of both invertebrates and of insects, including the [[mayfly]].