The main river of the district is the Nan River, with the Sirikit Dam creating a 250 km² artificial lake. The Pat River joins the Nan shortly below the dam.
Administration
The district is subdivided into 8 subdistricts (tambon), which are further subdivided into 84 villages (muban). Tha Pla and Ruam Chit are both subdistrict municipalities (thesaban tambon), covering parts of the same-named tambon. There are further 8 Tambon administrative organizations (TAO).