These data are comprised of beryllium-7 (7Be) and excess lead-210 (210Pbxs) activity for fine-grained, mobile, streambed sediment at seven reaches in the Little Flatrock Creek stream-channel network. This basin is monitored in cooperation with the Ohio Department of Natural Resources. During the period July 26-27, 2019 (summer low flow), the thickness and spatial extent of soft, mobile, fine-grained (mainly silt and clay) streambed sediment was inventoried and sampled along 150-meter (m) transects. A combination of stream corridor land-use distribution, valley type, channel slope, and stream order (Strahler, 1957) was used to select 15 rapid geomorphic assessment reaches using methods of Fitzpatrick and others (2016); streambed sediment from seven of these were analyzed for sediment fingerprinting and fallout-radionuclides (FRN).