the south fork. the "chutes" gauge only reads the release from cheeseman, it doesn't account for surface (rain) runoff below the dam, which is the primary contributor to waterton right now.
no water being diverted through roberts tunnel at the moment, since Denver shuts it down when it rains. Also, look at the roberts tunnel and n. fork gauge at grant, since the normal bailey gauge is not functional right now. Grant shows some water flowing in the n.fork based only on rain. Deer Creek and other small tribs contribute too. So, all the runoff below cheeseman and robert's tunnel = waterton, but bailey is almost certainly not at a runnable flow. here's the link: Colorado Division of Water Resources