Rivers of Thailand

Basin Pa Sak

Pa Sak River

แม่น้ำป่าสัก

Rises in the Phetchabun Mountains in Loei province. It flows south through Phetchabun, Lopburi and Saraburi to join the Chao Phraya River at Ayutthaya. It has the Pasak Jolasid Dam and the Rama VI Dam.

Map of the Pa Sak RiverNakhon SawanNakhon RatchasimaPasak Jolasid DamRama VI Dam
The dark line is this river; the mid-blue lines are its named tributaries.

Key facts

Length
about 735 kmMeasured along the river on this map; official figures can differ with the method used
Source
Loei province
Flows into
Chao Phraya River, Phra Nakhon Si Ayutthaya province
Basin
Pa Sak
Provinces (5)
Loei, Phetchabun, Lopburi, Saraburi, Phra Nakhon Si Ayutthaya
Tributaries on the map
Lop Buri River

Pa Sak River water level today

15 automatic gauging stations on this river, highest water relative to the bank first. As of 29 Sep 2026, 19:50

StationLocationLevel (m MSL)Of bank-fullStatusMeasured
Pa Sak 3Nong Phai District, Phetchabun93.97108%Over the bank29 Sep 2026, 19:50
บ้านบ่อวังWichian Buri District, Phetchabun63.33107%Over the bank29 Sep 2026, 19:00
Pa Sak 8Tha Ruea District, Phra Nakhon Si Ayutthaya6.81106%Over the bank29 Sep 2026, 19:50
ท้ายเขื่อนพระรามหกTha Ruea District, Phra Nakhon Si Ayutthaya7.18100%High29 Sep 2026, 19:00
Pa Sak 9Nakhon Luang District, Phra Nakhon Si Ayutthaya3.7098%High29 Sep 2026, 19:50
สะพานปรีดี-ธำรงPhra Nakhon Si Ayutthaya District, Phra Nakhon Si Ayutthaya3.7993%High29 Sep 2026, 19:00
ต.ในเมืองMueang Phetchabun District, Phetchabun114.7284%High29 Sep 2026, 19:00
Pa Sak 2Mueang Phetchabun District, Phetchabun115.6683%High29 Sep 2026, 19:50
บ้านพูลทรัพย์Chai Badan District, Lop Buri47.9974%High29 Sep 2026, 19:00
Pa Sak 1Lom Sak District, Phetchabun142.6669%Normal29 Sep 2026, 19:50
สถานีแพดับเพลิงMueang Saraburi District, Saraburi9.1568%Normal29 Sep 2026, 19:00
ต.ตาลเดี่ยวLom Sak District, Phetchabun143.0266%Normal29 Sep 2026, 19:00
บ้านป่าKaeng Khoi District, Saraburi11.2440%Normal29 Sep 2026, 19:00
ต.ตาดกลอยLom Kao District, Phetchabun193.7435%Normal29 Sep 2026, 19:00
ท้ายเขื่อนป่าสักชลสิทธิ์Phatthana Nikom District, Lop Buri18.9224%Low29 Sep 2026, 19:00

Data from the National Hydroinformatics Data Center (ThaiWater), HII, refreshed every 10 minutes

Frequently asked questions

Which provinces does the Pa Sak River flow through?
The Pa Sak River flows through 5 provinces: Loei, Phetchabun, Lopburi, Saraburi and Phra Nakhon Si Ayutthaya.
How long is the Pa Sak River?
The Pa Sak River is about 735 km long, measured along the river on this map. Official figures can differ slightly with the method used.
Where does the Pa Sak River come from?
The Pa Sak River rises in Loei province.
Which river does the Pa Sak River flow into?
The Pa Sak River flows into the Chao Phraya River in Phra Nakhon Si Ayutthaya province.
Which dams are on the Pa Sak River?
Dams on the Pa Sak River on this map: Pasak Jolasid Dam and Rama VI Dam.
What is the Pa Sak River water level today?
Of 15 gauging stations, 3 are over the bank and 6 have high water. Data as of 29 Sep 2026, 19:50.
What is the Pa Sak River called in Thai?
In Thai the Pa Sak River is แม่น้ำป่าสัก.

Other rivers in the Pa Sak basin

Lop Buri River