The number of early morning swimmers at Tring Sportspace pool has dropped, prompting bosses to encourage people to use the facility or face losing it.
There are adult dawn breaker slots between 6.30am and 8am Monday to Friday.
Marketing operations manager Nigel McArthur said: “I’ve been monitoring the usage over an extended period, and the early morning swim slots have been reducing.
“Nationally, casual swimming has declined and now plateaued, but club swimming is on the up.”
Tring Swimming Club – which trains three mornings out of five – has increased its sessions by half an hour to start at 6.30am.
Nigel said: “If people want to be able to continue early lane swimming, the best way they can do that is by using the facility.”