Benin became the 27th Party to the 1997 UN Watercourses Convention when it submitted its instrument of accession to the Secretary-General of the United Nations on 5 July 2012. Benin is the third country to join the Convention this year following Luxembourg ratification on 8 June 2012 and Denmark accession on 30 April 2012. According to recent press reports (here), the UK will soon join their ranks. The Convention will enter into force 90 days after the 35th nation submits its instrument of ratification, accession, acceptance, or approval to the UN Secretary-General.
You can find a prior post on the status of the Convention here.