Girls in the Upper Denkyira East district, in the Central Region, have been banned from crossing the River Offin,while they are menstruating - and on Tuesdays.
The ban, which is backed by traditional belief that menstruating girls are unfit to cross the river, is said to affect schoolgirls as well,Unicef's menstrual hygiene ambassador Shamima Muslim Alhassan has revealed.
The ban, apparently given by a local river god, has outraged children's activists, especially as girls must cross the river to reach school.
Shamima who could not fathom why such an outmoded tradition could be entertained in part of the country, said directive, which applies to part of the River Offin, violated girls' right to education.
"It seems the gods are really powerful aren't they?" she told BBC Pidgin
"Sometimes I think that we need to ask for some form of accountability from these gods who continue to bar a lot of things from happening, to account for how they have used the tremendous power that we have given them."
The traditional ban means girls in the Upper Denkyira East district, in the Central Region, could miss out on their education.
Sub-Saharan Africa is already struggling to keep girls in school during their periods.
The UN's scientific and education organisation, Unesco, estimates one in 10 girls in the region does not attend school because they are menstruating, while a World Bank report notes that 11.5m Ghanaian women lack the appropriate hygiene and sanitation management facilities needed.
Unicef's menstrual hygiene ambassador Shamima Muslim Alhassan told BBC Pidgin that the directive, which applies to part of the River Ofin, violated girls' right to education.
Central Regional Minister Kwamena Duncan has given indications he will coordinate with the Ashanti regional minister to find a solution, BBC Pidgin reports.
The River Ofin serves as a boundary between the Ashanti and Central Region,flowing through the Tano Offin Reserve in the Atwima Mponua District.
Many cultures have myths and taboos around menstruation.
A report by the BBC added that In Madagascar, some females are told not to wash during their periods and in Nepal some women are forced to sleep in huts away from the rest of the family.