- Knowledge about legal measures on water resources procurement for Thai agriculture is aimed to review legal knowledge on water resources procurement for agriculture according to the state basic policy to propose appropriate procedures to improve laws related to water resources administration and irrigation to become efficient and suitable to the current situation. It is found from the study that Constitution of the Kingdom of Thailand, B.E. 2550 stipulates the provisions regarding the state basic policy as procedures for law enactment and public administration indicating the intention of the constitution to build relation between state basic policy and government policy are duties of the state to provide water for agriculturist thoroughly. Major problem is insufficient water supply for agriculture due to unpreventable flood. It is therefore very necessary for the government to have good water administration. Water was formerly used in accordance with the provisions of Civil & Commercial Code, water in the sources jointly used by peoples was public asset but there was some control measures, namely, the owner of land along the watercourse had to use water only necessary to their land and any other person or group of persons who wanted to develop irrigation system of private section for agricultural purpose must comply with the condition set out in the Private Irrigation Act, B.E. 2482. In more developed society and more populations, both laws were unable to suitably and fairly prevent and solve problem of water abstraction between several groups of water user resulting the upstream inhabitants or economic influencers who referred their great necessity by virtue of the provisions of Civil and Commercial Code can pump water more than the others and cause trouble to the downstream inhabitants and low income earners while the water user in industrial and business sectors and water authority are able to catch water from the user in agricultural sector because the Private Irrigation Act, B.E. 2482 has controlled use of water only in agricultural sector. For any area where irrigation system was developed by public sector, use of water in irrigation area was under the governance of State Irrigation Act, B.E. 2485 which widely empowered the state officer to control the use, develop and allocation of water but the provisions of this law did not provide opportunity to the publics especially the opportunity of the water user to participate in the water administration according to the intention of the Constitution of the Kingdom of Thailand, and sometimes, water administration in irrigation area was not related to the water administration outside irrigation area. Drilling and using underground water was however under the provision of the Groundwater Act, B.E. 2520. Such operation was thus required to apply permission from the government authority but this law used to govern only underground water at the dept as prescribed by the Minister of Natural Resources and Environment, namely, the groundwater. For the construction of dam for using water in agriculture should be fully in accordance with the legal measures. In this regard, to minimize conflict and build understanding between the state and publics, the Act to Promote and Preserve the National Environmental Quality, B.E. 2535 should be revised by allowing people to participate in the environmental impact analysis and should the consideration of state conflicts or ignores those legal measures, the people should be entitled to sue to suspend dam construction. The findings form the study reveals that exercising the power to pushing the construction project is the right endeavor. The Government should do since dam construction is a being of public service which make the resources managed more efficiently. The study suggests that the Promotion and Preservation of National Environment Quality Act B.E.2535 should be amended by allowing citizen to participation in environmental analysis of the dam construction, Public Hearing should be pursued in every dam construction project, this Public Hearing will be used as the information support the decision making in further step.