The three subdistricts affected are
- Tha Pla (ท่าปลา), the 3 muban of the old subdistrict were added to Pha Lueat
- Hat La (หาดล้า), the 3 muban of the old subdistrict were added to Nam Man
- Charim (จริม), the 2 muban of the old subdistrict were added to Tha Faek
Also in 1970, the sanitary district Tha Pla was abolished (Gazette), and a new sanitary district with the same name was established on November 20 1973 (Gazette) - I mentioned this earlier as one of the former municipal areas.
Looking at a map gives the explanation for this - the Sirikit reservoir which was completed in 1973 and thus its area of 220 km² drowned most of the area of those three original subdistricts as well as the sanitary district as the old central town of the district. By the end of 1973 the settlements in those three subdistricts must have been moved already - thus they only consisted of so few muban. Maybe most of the population was moved to the area of Nam Man, and the newly created subdistricts then mainly consisted of the original communities relocated there.