Agreement on the Action Plan for the Environmentally Sound Management of the Common Zambezi River System (May 28, 1987) Countries/Territories Entry into force Simple signature Botswana May 28, 1987 May 28, 1987 Mozambique May 28, 1987 May 28, 1987 Tanzania, Un. Rep. of May 28, 1987 May 28, 1987 Zambia May 28, 1987 May 28, 1987 Zimbabwe May 28, 1987 May 28, 1987