Royal Irrigation Department is a government agency which has had long history and development. The water resources development with universal and systematic formats was in the reign of King Chulalongkorn the Great or King Rama V of the Rattanakosin Dynasty. His Majesty graciously established the "Canals Department" in B.E.2445 (A.D.1902), having the responsibility for canals maintenance to prevent the shallowness and canals excavation in the suitable area for transportation and storage for agriculture, assigned the government to recruit Mr. Yehoman vander Heide, a Dutch expert on irrigation to study and undertake the irrigation project planning in Thailand. Later His Majesty graciously appointed him as the first Director General of the Canals Department of Thailand and then the construction of a diversion dam across the Chao Phraya River in Chai Nat Province was proposed.
In the reign of King Mongkutklao or King Rama VI, His Majesty graciously gathered the activities of the Canals Department and established Krom Thod Nam or the Barrages Department instead in B.E.2457 (A.D.1914) and appointed Mr. R.C.R.Wilson, an English engineer, to be the Director General of the Barrages Department. At that time, the Barrages Department has begun the development of irrigation works to be in conformity with the technical principle for cultivation purpose and implemented the South Pasak Irrigation Project by constructing a large scale barrage across the Pasak River, the first barrage of Thailand constructed in accordance with modern civil engineering principles and named it Rama VI Barrage, located at Tha Luang Sub-district, Tha Rua District, Ayutthaya Province.
Later in the reign of King Phrapokklao or King Rama VII, the King considered that works which were being undertaken by the Barrage Department at that time were not only diversion, but also mainly concerned with the canals excavation and water distribution as well as water pumping for cultivated area. Therefore, His Majesty graciously renamed of the Barrages Department to the Royal Irrigation Department on 21 March B.E.2470 (A.D.1927). From then the water resources development has been continued its progress until at present.
The need of water, which is an essential factor in the national development in every aspect, has been increasing continuously, the construction works of water resources development in various scales and types have been scattered in every basin to cover all the regions of the country. Therefore, water is sufficient thoroughly and meet the requirement of people according to systematic and potential water management system.