The 13-kilometer-long (8.1 mi) 4.30-meter (14.1 ft) diameter tunnel-aqueduct system diverts waters from the Umiray River east of the Angat Basin.

[5] The Philippine government awarded the US$140 million contract to a Filipino-Italian consortium formed by SELI S.p.A, Grandi Lavori Fincosit S.p.A. of Italy, and J.V.

Angeles Construction Corp. Asian Development Bank (ADB) provided a $92 million grant, while the rest was financed by MWSS.

[6] When the contract was awarded to the Filipino-Italian consortium as they had the available tunnel boring machines (TBM) which usually would take a year to manufacture and deliver onsite.

Fidel V. Ramos released Proclamation 264, establishing the Umiray River Watershed Reservation, which encompasses 16,722.75 hectares for the sole purpose of maintaining and conserving the water basin for the UATP.

[12] In November 2019, President Rodrigo Duterte ordered the continuation of the tunnel, with Congressman Danilo Suarez providing a support last July 2020.

To transport operations & maintenance workers, and material, a suspended railcar system was also constructed in the main tunnel and is used during low-flow.