Two tributary watersheds¬ Cottonwood Creek and Little Dry Creek¬ to the greater San Joaquin watershed, in California’s Central Valley were assessed for sediment and flow dynamics, between water years (Oct. 1 to Sept. 30) 2011 and 2019. The two systems deliver suspended sediment to the San Joaquin River below Friant Dam, California. Because these two creeks are directly down river of Friant Dam, they become the most upstream source of sediment to the San Joaquin River below Friant Dam. Thus, is it important to assess their contribution to the San Joaquin system. Flow from each creek watershed, along with the San Joaquin River, was compared to continuously measured water surface elevations to quantify flow direction and timing. Suspended sediment was sampled using multiple automatic samplers and analyzed for concentration and grain size distribution.