Surface Runoff (Water Bodies and Natural Drainage)
According to the National Irrigation Authority (NIA) District Office, there are ten (10)-identified surface water sources in the city. Out of this figure, five are not dependable with regards to water yielding capacity. Alternatively, there are five existing irrigation facilities being utilized by the farmers. Of these five, 4 are brush dams and 1 intake dam. These are sequentially located at barangays San Juan, Villa Joson, Palestina, Pinili and San Agustin.
On the other hand, there are two irrigation systems currently serving the agricultural land within the city. The Talavera River Integrated Irrigation System (TRIIS), a major water tributary, transverse the northern to southeastern section of the city draining itself to parts of the municipalities of Llanera and Talavera, while the Upper Pampanga River Integrated Irrigation System (UPRIIS) directly benefits 3 rural barangays in the town namely Tondod, A. Pascual and San Mauricio resulting to almost 3 cropping seasons per annum. Moreover, there is an on-going sub- basin irrigation feasibility study being conducted by the project research group of the Casecnan Multi- Purpose Irrigation and Power Project Inc. (CMIPPI). This study will identify other possible sources of irrigation water for areas not covered by the CMIPPI in the city.
Several natural drainages (creeks) criss-cross the poblacion area supported by 52.8065 drain kilometers of man-made drainage system. These creeks eventually empty itself along the boundaries of the towns of Muñoz and Lupao in the Southwestern area of the city. Prominent of these water systems are Cumabol and Panlasian Creeks.
Groundwater Resources/ Hydro-Geologic Characteristics
Geologic data from the Bureau of Mines indicate that only the upper Miocene, Pliocene and Pleistocene sedimentary rocks and the quarterly alluvium can be considered as important ground water reservoirs. The older rock formations are either too light to contain and yield significant amount of water or can be found only at a depth to which groundwater is economically feasible. A geologic map, prepared by the cartography division of the Bureau of Soils and Water Management from 1987-1988, reveals that majority of the land area of the City are recent in lithological age. Its coverage area includes the major parts of the southeast and midwest of the city.
Most of the aquifers within the recent alluvial formations are within the shallow well areas (within 20 m) Average static water level is 5.34 mbgs On the other hand, the average well depth is 3.54/m, while the average specific capacity is 0.31 lps/m.