Simplify the following text for a Grade 8 native English-speaking person.
Original: In 1972 Mali , Mauritania and Senegal founded the Organisation pour la mise en valeur du fleuve SÃ nÃ gal ( OMVS ) to manage the river basin .
Simplified: In 1972 , Mali , Mauritania and Senegal made the Organisation pour la mise en valeur du fleuve SÃ nÃ gal ( OMVS ) .