Sirinthon Dam

Sirindhorn Dam blocks the Lam Dom Noi river — a tributary of the Mun River — in Sirindhorn District, Ubon Ratchathani. The stone-and-clay-core dam is 42 metres high, 940 metres long, and 3.5 metres wide, holding back a reservoir that covers 288 sq km. The grounds are free to enter, daily 06:00-18:00.

A Working Dam, Not Just A Viewpoint

The Electricity Generating Authority of Thailand (EGAT) commissioned the dam in 1971 for hydropower, irrigation, flood control, and fisheries — locals still call it “Dom Noi Dam” after the river it dams, at a site known as Kaeng Sae Noi. Near the dam ridge, EGAT laid out a shaded public garden in 1991 to mark HRH Princess Sirindhorn’s 36th birthday, and it remains the main lakeside green space for visitors today.

What’s On The Reservoir

In 2021 EGAT installed a floating solar array on the reservoir — around 144,000 panels adding 45 MW of capacity, which made it the largest hydro-floating solar hybrid project in the world at the time it opened. The same year brought a new Nature Walkway along part of the shoreline, giving views over both the water and the solar installation. Further out on the reservoir, away from the dam itself, sits Hat Pattaya Noi (“Little Pattaya”), a cluster of raft-house restaurants and a fishing community — a separate stop covered on our Pattaya Noi page rather than part of the dam grounds. A golf course operates at the reservoir’s north end.

Atmosphere & Timing

The dam and garden draw a mix of EGAT-related day-trippers, birdwatchers, and locals out for a walk rather than crowds of tour buses. Early morning brings the calmest water and the coolest temperatures for walking the ridge or the Nature Walkway; the reservoir’s scale means there’s always more shoreline than visitors.

Practical Information

Insider Tip: Time a morning visit to combine the dam ridge and Nature Walkway with a stop at Hat Pattaya Noi for lunch on a raft restaurant — the two sights sit on the same reservoir but are different experiences, about 8 km apart by road.

Watch out: This is a working hydroelectric dam, not a designated swimming beach. Keep to signed areas and stay well clear of the spillway and the floating solar farm, where currents and boat traffic pose real risks.

There’s no public transport aimed at tourists; a car or hired driver from Ubon Ratchathani town is the practical way in. For dam details or to check access, call the site office on 0 4536 6081.