National Irrigation Board (NIB) was established and incorporated in 1966 as a state corporation through the Irrigation Act CAP 347 of the Laws of Kenya. The Act provides its original object as; “To provide for development, control and improvement of irrigation schemes and for purposes incidental thereto and connected therewith”. The transformative Constitution of Kenya 2010 (CoK2010) has changed the legal, statutory, operational and management context of irrigation. This had been furthered in the Medium-Term Plan III (MTPIII) of the Kenya Vision 2030(KV2030) and cascaded in the NIB strategic plan 2013-2017. 

As per the act, NIB manages seven public schemes in Kenya namely Mwea, Bura, Tana, Ahero, West Kano, Perkerra and Bunyala irrigation schemes. These public schemes are developed on land held in trust by NIB for the Government. In addition, NIB runs two (2) research stations namely Mwea Irrigation Agricultural Development (MIAD) Centre and Ahero Irrigation Research Station and two (2) subsidiaries namely Mwea Rice Mills Ltd (MRM) and Western Kenya Rice Mills (WKRM).

In line with the Constitution of Kenya 2010 (CoK2010), NIB is obligated not only to be responsible for undertaking irrigation development within the seven schemes but to also widen the delivery of its services all over the Republic of Kenya.