In August, 2022, pebble counts were conducted in a reference reach of the Kalamazoo River upstream of Plainwell, Michigan (MI) to characterize the substrate size within the reach. These data were collected to accompany elevation data collected for the reference reach in October, 2021. A reach composite pebble count was conducted, consisting of 101 samples collected along 34 transects spanning the entire 500 m reach. Sample locations spanned multiple geomorphic unit types, including riffles, pools, and run/glides. Additionally, a separate 100-sample pebble count was conducted in a riffle near the head of the reference reach. The riffle data were collected in the same location as a 2010 survey and pebble count, allowing comparison over time. Substrate size was measured with a gravelometer for sediment >2 mm and with a sand card for sediment in the 0.063 mm - 2.0 mm range. For both the reach composite and riffle cross-section counts, sediment size ranged from silt/clay (< 0.063 mm) to >90 mm. In addition to the quantitative measurements, samples were also characterized categorically following methods used in previous post-oil spill substrate mapping in the Kalamazoo River, which was used in sediment remediation assessments (TetraTech, 2012). Finally, measurements of soft sediment depth were recorded, where it was present overlying the bed surface.