Stefan, HeinzWood, Addison2011-10-212011-10-211976-12https://hdl.handle.net/11299/116953Dissolved oxygen, water temperatures, Secchi depth, and surface drift currents were measured in pool No. 2 of the Mississippi River during very low flow conditions from August 24 through September 25, 1976 on eleven different days and under significantly varied weather conditions. Water quality parameters were found to vary, both in time and space and in direct relationship to prevailing weather, particularly wind and sunshine. With total river flows from approximately 1000 to 2000 cfs, the measured D.O. distributions, water temperatures, and transparencies were predominantly typical of a series of interconnected lakes and to a lesser degree typical of a river. Natural convection, density currents, and wind drift were found to be of great importance. Recovery from low dissolved oxygen levels due to the effluent from the Metropolitan Waste Treatment Plant occurred in the pool upstream from Dam No. 2 mainly as the result of photosynthesis, surface aeration, and the hydrodynamic exchange processes between different regions of the pool.en-USReport