Total streamflow across the Flat River was last observed at 39 cfs, and is expected to yield approximately 77 acre-ft of water today; about 48% of normal. River levels are low and may signify a drought. Average streamflow for this time of year is 81 cfs, with recent peaks last observed on 2025-02-13 when daily discharge volume was observed at 7,090 cfs.

Maximum discharge along the river is currently at the Flat River At Bahama reporting a streamflow rate of 38.7 cfs. However, the streamgauge with the highest stage along the river is the Flat River Trib Nr Willardville with a gauge stage of 1.49 ft. This river is monitored from 3 different streamgauging stations along the Flat River, the highest being situated at an altitude of 353 ft, the Flat River At Bahama.