In the oil sands industry, composite tails (CT) is a tailings management approach in which the fines or clay fraction of extraction tailings are mixed with the coarse sand fractions, such that, with the addition of a coagulant aid, a non-segregating deposit is produced. Various coagulant aids have been shown to be effective. In the process of coagulation, the fine solids aggregate. Under self-weight consolidation (aided by high proportion of sand grains), particle-free water is released from the deposit leaving the fines solids and some water trapped within the voids of the coarse solids matrix. The rate and degree of water release determines when the resulting deposit can be classed as a “dry” landscape for reclamation. The coagulation of the clays has been demonstrated with a variety of chemicals, both organic and inorganic. Depending on the particular coagulant aid, various changes in pH, salinity, cation and anion levels, buffering capacity and toxicity have been observed. The impacts of some of these coagulant aids on water quality are described and the potential influence of the CT release waters on operational aspects of oil sands operations and on eventual reclamation options are discussed.