Question:
I am working to hydro-condition a watershed that has a heavily developed area. Sometimes water goes into storm ponds so I leave that impeded flow alone, but sometimes water flows into underground systems where I can’t find the output. In that situation, how should I handle incorrect impeded flow?

Answer:
Is the urban area at the mouth of the stream or in the middle of the watershed? If it the urban area has no agricultural areas between itself and the mouth of the stream, no ag practices will be placed in those areas anyway so it'd likely be best to just use an educated guess to make the stream network look plausible and concentrate on the ag areas. If the stream network flows through the urban area then through ag areas afterwards, you might contact the city to see if they have any storm water infrastructure GIS files, particularly storm sewer mains. If so, you could simply burn the mains in as cutlines since the inlets/outfalls will fall along the mains. Otherwise, does the SIGGIS extension help locate any of the outfalls?