‘Essential maintenance works’ are to be carried out at Warnham Nature Reserve next week.
Environment Agency officials say that they will be working on a dam embankment at the reserve and will have to drop the water level while the works are carried out.
The works are due to start on Monday and could last up to two weeks.
The reserve - which will remain open during the works - is owned and run by Horsham District Council.
Horsham Councillor Christine Costin posted details from the Envirohment Agency on social media in which officials pointed out that visitors ‘should be aware that during this period wildfowl populating the site are likely to be temporarily affected.’
However, they said, ‘the welfare of the fish population will be a key priority.’
Christine Costin says she has urged the council to ensure ‘careful monitoring’ while the works are undertaken.
She added: “The wildife habitats at Warnham Millpond support a host of fascinating species. A brilliant place that is greatly loved.”