The Dyle rises in Houtain-le-Val. At this location, you will find a valve to regulate the water level with the text "Les sources de la Dyle". Apparently, many people think that the adjacent pond, where you occasionally see local fishermen (otherwise you are not allowed to enter the grounds) are the sources of the Dyle and that the valve on the central road indicates this.
But that is not true. If you look closer or go onto the adjacent meadow and pond path, you will see that the Dyle is already a small stream here. The valve was built by order of the Countess d'Hanin de Moerkerke who lived in the castle of Houtain-le-Val, on the other side of the road. She wanted to be able to regulate the level of the pond in this way.
The Dyle flows further into the domain of the castle here, which you can see very well from the side entrance, at the small car park.
In other words: this is not the official source of the Dyle. You can see this very well if you zoom in on the map and look at the watercourses that lie behind the pond and that also feed it.
Something else about the d’Hanin de Moerkerke family. They originally come from the Land van Waas. Count Fernand-Auguste-Joseph d'Hanins de Moerkerke, born in 1840, married Marie de Waha and thus became heir to the castle and the domain in Houtain-le-Val that belonged to the Wahe family. The last male Count d'Hanins de Moerkerke in Houtain-le-Val was Count Henri d'Hanins de Moerkerke (died in 1963) who had three daughters who have also died: Anne, Monique and Isabelle. The flap that you see here with the text "Les sources de la Dyle" was installed by this last generation at the beginning of the twentieth century.