I'm working on a model railroad and when I activate a water effect layer it not only covers the entire route at about 0m high, but it also extends out into the aisleways created by digholes. I lower the layer to -0.1 and it disappears below ground but remains visible in the aisles, as well as some lower portions of the route. Is there a way to delete portions of a water effect layer so that I can have a lake right up against to the fascia, that doesn't extend into the aisle?