- investigate and study all available and possible water resources in the Philippines, primarily for irrigation purposes; to plan, design, construct and/or improve all types of irrigation projects and appurtenant structures; to operate, maintain and administer all national irrigation systems; the authority to supervise the operation, maintenance and repair, or otherwise, administer temporarily all communal and pump irrigation systems constructed, improved and/or repaired wholly or partially with government funds, and to delegate the partial or full management of national irrigation systems (NIS) to duly organized cooperatives or associations;
- charge and collect from the beneficiaries of the water from all irrigation systems constructed by or under its administration, such fees or administration charges as may be necessary to cover the cost of operation, maintenance, and insurance; and to recover the cost of construction within a reasonable period of time to the extent consistent with government policy; to recover funds or portions thereof expended for the construction and/or rehabilitation of communal irrigation systems which shall accrue to a special fund for irrigation development;
Unpaid irrigation fees or administration charges shall be preferred liens, first upon the land benefited, and then on the crops raised thereon, which liens shall have preference over all other liens except for taxes on the land. Such preferred liens shall not be removed until all fees or administration charges are paid or the property is levied upon and sold by NIA for the satisfaction thereof. Judicial actions for the collection of unpaid irrigation fees or charges, drainage fees or other charges which the NIA is authorized to impose and collect, shall henceforth be governed by the provisions of the Rules of Court of the Philippines;
- construct multiple-purpose water resources projects designed primarily for irrigation, and secondarily for hydraulic power development and/or other uses such as flood control, drainage, land reclamation, domestic water supply, roads and highway construction and reforestation, among others. Provided, that the plans, designs and the construction thereof, shall be undertaken in coordination with the agencies concerned.
- investigate, in coordination with the Department of Public Works, areas which are unproductive or less productive due to permanent or occasional submergence; to plan, design and construct drainage facilities and protective works for agricultural purposes to increase or maximize their productive yield; to collect drainage fees from landowners of areas benefited by the drainage facilities and protective works to recover the cost of operation and maintenance as well as a reasonable portion of the cost of the construction thereof, consistent with government policy
- acquire, by any mode of acquisition, real and personal properties, and all appurtenant rights, easements, concessions and privileges, whether the same are already devoted to private or public use in connection with the development of projects by NIA;
NIA is empowered to exercise the right of eminent domain in the manner provided by law for the institution of expropriation proceedings.
In the prosecution of its projects, the NIA is hereby given the right of way to construct and maintain such works and hydraulic structures over and throughout lands of the public domain, and in those owned by any branch of the government, political subdivision, and instrumentality.
- establish/create such services and facilities and other means of social and economic assistance to the community which might be adversely and directly affected by the construction of NIA projects; and to do all such other things, and to transact such business, as are directly or indirectly necessary, incidental or conducive to the attainment of the above powers and objectives, including the power to establish and maintain subsidiaries; and in general, to exercise all the powers of a corporation under the Corporation Law.
NIA's roles in agricultural development are further defined under the Agriculture and Fisheries Modernization Act, RA 84354. The Agency shall be involved in the following:
- Preservation and rehabilitation of watersheds to support the irrigation systems in coordination with other agencies, particularly the Department of Environment and Natural Resources (DENR)
- Research and Development in the development of effective, appropriate and efficient irrigation and water management technologies
- For NIS
- planning, design, development, rehabilitation and improvement
- operation and maintenance of major irrigation structures including headworks and main canals
- gradual turnover of operation and maintenance of secondary canals and on-farm facilities to Irrigators Associations
- Provision of technical assistance to local government units to complement the devolution of the planning, design, and management of communal irrigation systems
- Formulation and development of a plan for the promotion of a private sector-led development of minor irrigation systems
- Encouraging the construction of irrigation facilities thru other viable schemes like Build-Operate-Transfer, Build-Transfer and other schemes that will fast track the development of irrigation systems
- Review of irrigation service fee rates and recommendation of reasonable rates