A view of the discharge / throat of a 3-inch fiberglass Montana flume.  Lacking an extended throat or discharge section, flow from a Montana flume must freely spill off the end of the flume.

The flume has in inlet approach section with pipe stub and mounts a molded-in probe well on the right side of the flume.  The location of accessories in a flume is determined looking down the flume in the direction of flow.