One of the UK’s rarest species of bird has been spotted in the area.
Two bitterns were found feeding in the reedbed at Marsworth Reservoir by its owners, Herts and Middlesex Wildlife Trust (HMWT).
The bittern is a small brown heron and is one of the most threatened bird species in the UK.
It is also very hard to spot as its brown streaked plumage acts as camouflage as it hunts for food in reedbeds at the edges of wetland.
HMWT has doubled the areas of wet reedbed in Herts to 22 hectares since 2002.
HMWT conservation manager Mr Hill said: “Reedbeds support a great variety of wildlife and the rare bitterns particularly need reedbeds where there are plenty of small fish – their main food.”