The southwestern portion of the municipality whose terrain is generally flat has an average elevation of 94.0 meters above sea level while the eastern portion, about 5.0 kilometers from the poblacion, starts to rise from 200.0 meters above sea level to a maximum of about 1000.0 meters above sea level.
The northeastern Caraballo Mountain has a slope that varies from 8-15%, 15-30% and 30-50%. The lowland which comprises about one-third (1/3) of the municipal land area is relatively flat with 0-30% slope. Area occupied per slope category areas follows:
0-30% ( 7,030 hectares)
8-15% ( 4,865 hectares)
15-30% (10,899 hectares)
30-50% ( 677 hectares)
The three major rivers that traversed the municipality, namely: Agno River; Sabangan River; and Ambayoan River, flow from the northeastern Caraballo mountains face water drainage of the municipality.
Sources:
Sherwin Bartolome Soria
http://snml.weebly.com/municipality-of-san-nicolas-history.html
A Pangasinan Folio’70 : a historical document
2007 San Nicolas Town Fiesta Souvenir Program
2005 San Nicolas Town Fiesta Souvenir Program
1968 San Nicolas Town Fiesta 1968 Souvenir Program