G.R. No. 185184 - Metropolitan Waterworks and Sewerage System, represented by Diosdado Jose M. Allado, vs. Provincial Government of Bulacan, represented by Josefina M. Dela Cruz

The Provincial Government of Bulacan (Respondent) filed a Complaint for Specific Performance/Payment of National Wealth Share against the Metropolitan Waterworks and Sewerage System (MWSS) (Petitioner).
The controversy concerns the equitable share allegedly due Bulacan arising from the utilization and development of waters from Angat Dam, located within Bulacan's territorial jurisdiction.
Respondent claimed that MWSS derives proceeds from water resources of Angat Dam and is constitutionally and legally obliged to pay Bulacan its share under Section 7, Article X of the 1987 Constitution and Sections 289, 291, and 292 of the Local Government Code of 1991 (LGC).
Petitioner contended lack of cause of action and denied engagement in utilization and development of natural resources, emphasizing it is a non-profit public service utility offering potable water supply to Metro Manila.

The Regional Trial Court (RTC) ruled in favor of the Provincial Government of Bulacan, ordering MWSS to furnish financial statements and remit Bulacan’s national wealth share based on earnings from 1992 to present.
The Court of Appeals (CA) affirmed the RTC decision with modifications, directing computation of the share pursuant to Section 291 of the LGC.
Petitioner filed a Petition for Review on Certiorari before the Supreme Court, assailing factual findings, reliance on documents such as NAMRIA Topographic Map and NPC letter, applicability of the water as national wealth, and the characterization of MWSS as engaged in utilization and development.

The Court required comments from NPC, National Irrigation Authority (NIA), and National Water Resources Board (NWRB).
NPC confirmed it had been paying national wealth tax based on utilization of waters while it managed the Angat Hydro Electric Power Plant (AHEPP) prior to its 2014 privatization; main dam and spillway remain under government ownership.
NWRB clarified water permits are issued from Angat River sources, not from Angat Dam which is a reservoir.
Petitioner maintained continuity with earlier positions; no legislative ordinance authorized respondent to impose tax on petitioner.

Whether the water impounded in Angat Dam is "national wealth" within the meaning of Section 7, Article X of the 1987 Constitution and related statutory provisions.

Whether the water in Angat Dam is located within the territorial jurisdiction of the Province of Bulacan for purposes of equitable sharing.

Whether Metropolitan Waterworks and Sewerage System (MWSS) is engaged in the utilization and development of national wealth, thereby incurring liability to pay Bulacan its equitable share.

Whether the petitioner MWSS is obligated to pay respondent the national wealth share under Section 291 of the Local Government Code without an ordinance passed by the Sangguniang Panlalawigan.