Tagudin River Irrigation System is the eldest and the third gravity irrigation system in the province of Ilocos Sur. Its water supply comes from the Chico River. Sitio Dalisis of Barangay Cabugao, the town of Suyo is the junction of the main flow of the river and the channel leading to the Intake with an approximate length
of 1.25 kilometers winding roughly along the Cervantes road.
The Intake is located in Barangay Cabugao. It is furnished with four big steel gates followed by a 982-meter tunnel connected to 1.243 kilometers main canal which branches thru a bifurcation, the 7.160 kilometers North lateral, extending up to a portion of the town of Sta. Cruz.
South lateral with a total length of 5.55o kilometers and a drainage canal which is provided with a check to irrigate the western portion of the irrigable area and ends on the sandy beaches of the China Sea.
The system is operated by gravity whose main source of the water supply comes from Chico River. The Intake is surrounded by mountains, hills, and plains.
It was constructed during the Japanese regime.
Tales say that during the Japanese time, the tunnel served as a hiding place from enemies, an exit way going to Burayok (Baringcucurong) and a place where they put their gold and weapons.