I can recognize one face in this one, that of my husband’s grandfather Doede (Douglas) Jaarsma. He’s sitting inside the sluice, third of the boys from the left, just next to the older man standing on the left. There’s a small handwritten X just below him. I’m assuming this is either a group of employees or school boys, and I’m leaning towards the latter since there’s only one man in the group that looks older and is presumably a teacher. Doede went to a technical high school and became a blacksmith. These boys all look to be either in their late teens or early 20s, so since Doede was born in 1911, this was probably taken somewhere around 1930. A couple of the young men do have wedding rings, so it’s possible this was taken as late as 1941, before Doede himself was married. To me, the trough structure looks like some kind of mill sluice, meant to direct water to a water wheel or sawmill possibly – it’s a little odd since the Netherlands is SO flat, especially in Friesland where this was likely taken, I can’t imagine how/why water would be first carried up so high and then brought back down. It’s a pretty interesting photo!