Reach 3: Primary Driver—Imported Dissolved Oxygen
DO concentrations in Reach 2 entering Reach 3 are generally at or above saturation levels, based on DO concentrations measured at Mossdale, even at low summer flows, suggesting that reaeration and algal photosynthesis are dominant processes in Reach 2 (Data Atlas 2006) (Kratzer et al. 2004). The figure below shows the DO concentrations measured at the California Department of Water Resources monitoring station at Mossdale, midway along Reach 2, during 2001. These DO values were at or above saturation for nearly the entire year (Jones & Stokes 2002a). As flow continues downstream, DO concentrations may decrease, but DO is generally observed to be near saturation at Channel Point during ebb tide (i.e., downstream flow).