Swimmers at a council-run pool have been barred from doing backstroke at busy times - because it is considered to be too dangerous.
Backstroke is now banned at certain times
Daisyfield Swimming Pool in Blackburn is understood to be one of the first in the country to introduce such a move.
It is hoped the ruling will prevent any legal action against the council if a swimmer collides with someone.
It follows the publication of new guidelines - suggested by the Institute of Sport and Recreation Management.
Last year, Blackburn with Darwen Council was one of the first to ban picture-taking mobile phones from its baths.
No safety flags
There had been concerns that they could be used by paedophiles to take pictures of semi-naked children.
Daisyfield Swimming Pool in Belper Street, Blackburn is a deck access pool, where the water level meets the side of the pool walls.
There are no safety flags in place marking the end of the swimming area.
Steve Rigby, executive director of culture, leisure and sport, at Blackburn with Darwen Borough Council, said: "Lane swimming at Daisyfield Pool is proving very popular.
"This has resulted in us requesting that people do not swim back-stroke during these busy sessions, in order to avoid any dangerous collisions.
"We encourage those who wish to swim backstroke to visit at quieter times of the day."
Last year, a water polo team was banned from practising at the venue because of the fear that stray balls were a danger to the players.