Northbrook Swimming Pool in Exeter will be closed after a decision at an Exeter City Council meeting held on Tuesday evening.
Older people, schoolchildren and lower income families are likely to be most affected by the closure of the pool.
Northbrook is the third leisure facility to be closed since 2018 by the Labour-led authority, which is understood to have spent about £44m on the new St Sidwell's Point facility which opened in 2022.
City council leader Phil Bialyk said it was a "very difficult decision due to low usage compared to high running costs".
Staff at Northbrook were told in February a decision had already been made to close the pool due to leisure centre service budget cuts of £586,000, but, after a public outcry, Exeter City Council held a six-week public consultation.
More than 2,000 people signed a petition against the pool closure.

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