The largest reservoir in Central Thailand is Pasak Jolasid Dam. Is it 4.8 kms long and stretches across Lopburi and Saraburi Provinces. It has a storage capacity of up to 960 million cubic meters. The project was initiated by H.M. The King in the early 1990’s and was officially opened in 1999. Pasak Jolasid Dam is a source of water for households, factories and farms in the Pasak Valley. It has also helped greatly with water management in the Chao Phraya Valley which often suffered from flooding during the rainy season. The Pasak River is a major tributary of the Chao Phraya River, flowing eastwards through Phetchaboon, Lop Buri and Saraburi Provinces, and joining the Chao Phraya River in Ayutthaya Province. Before the building of the dam, this river was one of the main sources of flooding in Bangkok.
Pasak Jolasid Dam is now a major tourist attraction for people travelling in Lopburi Province. For us, we went there for lunch before heading on towards Lopburi city to see the monkeys. It is possible to do this loop as a day-trip from Bangkok. Though, to make it a more worthwhile day, it is a good idea to do it between November and January when the sunflower fields are blooming with bright yellow colours. A recreational park has been created at the southern end near the dam. There are plenty of food vendors here and you can buy some food to eat as a picnic along the waterfront. There is often a cool breeze here and it is a great place to come to escape the heat of the day, There is also an interesting museum with free entry which details the history of the reservoir as well as the social history of the local inhabitants.
You can join tractor and trailer tours of the dam for a very cheap price. The commentary during the tour is only in Thai language but fortunately the tour price is the same for Thai people and foreigners. Really they should offer us a discount but it was so cheap anyway. It was a very windy trip across the dam. On the other side there is a giant seated Buddha image. I thought that was our destination but the tractor did a u-turn and took us straight back without stopping. There wasn’t really that much to see on the journey across so I am not sure whether it was really worth it. But, each trip was always full with Thai tourists. No foreigners here at all. Nearby there is a railway station, and it is possible to take a train ride across the lake. I haven’t done it yet but judging by satellite pictures the train crosses some of the longest bridges in Thailand. Instead of going around the lake, the train tracks go over the water for much of the way.