To accelerate the social development of the provinces and cities comprising Region IV, Executive Order 103 dated May 17, 2002 divided the region into Region IV-A (CALABARZON) and Region IV-B (MIMAROPA).

Region IV-B or MIMAROPA (Mindoro Oriental & Occidental, Marinduque, Romblon, and Palawan) refers to the cluster of emerald islands and islets stretching across the warm tropical seas south of southern Luzon, composed of 2 cities, 71 municipalities and 1, 458 barangays. It is archipelagic having no land border with another region. It is bounded in the north by CALABARZON (Cavite, Laguna, Batangas, Rizal and Quezon) and Verde Island; in the southeast by Bicol region and Pacific Ocean; in the south lies Panay islands and on the west is South China Sea. MIMAROPA has a total land area of 2,745,720 hectares representing 9% of the country’s land. The 2010 Census revealed that MIMAROPA has a total population of 2,522,998.

The region’s economy relies mostly on agriculture, fishing and ecotourism. It is one of the producers of the country’s top export products like rice, banana, coconut, cashew, and papaya. The region is also the second top producer of fish and seaweed in the country. 

MIMAROPA is one of the busiest regions in terms of tourism.

Region IV-B is home to:

Mindoro Oriental – The Loveliest Harbor in the Island

Mindoro Occidental – The Marine Wonderland

Marinduque – The Lenten Capital

Romblon – The Marble Capital

Palawan – Home of the New Seven Wonders of Nature



Adopting the provision of EO No. 103, NIA created a separate regional office at Region IV-B which was effected by virtue of NIA Board Resolution 7678-11 dated March 14, 2011 and Office Memorandum 26-2011 dated March 29, 2011 issued by Administrator Antonio S. Nangel. The regional office was established at Calapan City, Oriental Mindoro in accordance to Executive Order No. 682, designating Calapan City as the regional center of Region IV-B.  

The NIA IV-B regional office is accessible by land-sea transport facilities. Calapan City is about 2 hours travel from Batangas Port via Roll-on/Roll-off ships and from Calapan Port, the office is 7 kms. travel via public/private vehicle.

NIA Region IV-B is headed by Regional Irrigation Manager Ramon P. Ragodon and  Division Manager Engr. Cesar M. Pobre. The Regional Office is composed of dynamic personnel joining hand in hand to achieve the agency’s goals.

NIA Region IV-B covers 3 irrigation management offices headed by Acting Division Managers: MOMARO IMO (Mindoro Oriental-Marinduque-Romblon), Occidental Mindoro IMO and Palawan IMO.

Some of NIA Region IV-B’s irrigation projects were the Iwahig Balsahan Prison and Penal Farm Irrigation Project in Palawan, Sablayan Prison and Penal Farm Irrigation Project in Occidental Mindoro, Ibato-Iraan Small River Irrigation Project (SRIP) in Palawan, and other national projects.



Memorandum from the Executive Secretary - Office of the President, the Secretary of the Office of the Cabinet Secretary was designated Acting Chairperson of the NIA Board of Directors, 3 November 2016.