Question:
I am getting strange outputs from the “Stream Reach & Catchments” step. Why are additional segments being added to the stream reach?

Answer:
Image from the user: The original DEM is in UTM15 and the ACPF geodatabase is in UTM14. I changed the projection of the DEM to UTM14 to match. I've ran into this when my flow network did not match up with the flow direction and accumulation rasters after running the manual cutter/dam builder. We encourage you to re-run the flow network tool after you finished making cuts.

• Response: We did re-run the flow network tool following the cuts. There is a HUC8-level breachline file we have to work from and we clip it down to the HUC12 level and project to UTM14 and we have to reproject the DEM to 14 with the new ACPF geodatabases as well. I am thinking there is something off with how the data is being projected. We did all the same steps using the previous generation of geodatabases and everything is running just fine.

If you believe that projecting the DEM is causing the trouble, you could leave the DEM in its native projection and project the ACPF fgdb to match. There is a 'Project ACPF Workspace' tool in the Utilities tool drawer. This tool will project the complete contents of your ACPF workspace to a projection of your choice...UTM zone 15, I am guessing...to the named output folder. I would be interested in hearing if your results are any different. Using this tool would help answer any questions you have about projecting DEMs.