The analysis of system metabolism is integral to our understanding of an ecosystem. By quantifying metabolism via changes in diel dissolved oxygen concentration, we can determine whether a stream is autotrophic or heterotrophic in nature, which establishes the base for food web studies (Dodds and Cole 2007). Due to their clear, open channels, river food webs can rely heavily on primary production (Thorp and Delong 2002). Using modern logging sensors and models (Riley and Dodds 2012), we will examine and compare system metabolism among different hydrogeomorphic zones at each river during base flow. Metabolism data will be collected from main channels of all river sites, as well as in the slackwaters of more structurally complex river sites. Probes will measure light, DO, temperature, and discharge over several days. Barometric pressure and discharge will be measured using an acoustic doppler velocimeter. Benthic and suspended chlorophyll, benthic stocks of fine and coarse benthic organic material, and standing cover of macrophytes and filamentous algae will also be quantified. We hypothesize that primary production, as opposed to community respiration, is of greatest influence to community structure. Therefore, we expect to observe autotrophy occurring in our study rivers.