The term "Marikina Watershed" is sometimes used to specifically refer to this protected area, but is also generally to the river's entire drainage basin, from the Sierra Madre Mountains of Rizal Province all the way to the Napindan area in Pasig, where its mouth empties into the Pasig River.

"[4][5] The area officially referred to as the Upper Marikina River Basin Protected Landscape covers 26,125.64 hectares,[3] covering the upper reaches of the Marikina watershed in the Province of Rizal, flowing through the Antipolo, Baras, Rodriguez, San Mateo, and Tanay.

Near the boundary of Marikina and Pasig cities, the river meets the gates of the Manggahan Floodway, a controlled waterway used to prevent flooding in Manila during heavy rains by diverting most of the water of the Marikina towards Laguna de Bay (i.e. Laguna Lake) instead of the Pasig River.

[9] Further downstream the Nangka River and its own tributary in the Sapang Labo Creek mark the Boundary between San Mateo and Marikina.

[11] The name of Barangay Tumana, in the Tagalog language, means a fertile highland above water level.

Instead, these waterways are linked in a complex network with the Balanti, Halang, and Muntingdilao Creeks and the Sapang Baho River, eventually emptying into Manggahan Floodway and Laguna de Bay.

Its stated objective was "to protect the watershed of the Mariquina River, the source of the water supply of the city of Manila."