Excess phosphorus levels in water ways can lead to eutrophication. A low cost measure to reduce P levels may be to use Water Treatment Residuals (WTRs), which are otherwise shipped to a landfill or stockpiled in a drying field for blending and future land application. Two WTRs were selected for this study: an alum-based WTR and an alum-based WTR augmented with powdered activated carbon (PAC). Additionally, a study is being performed to investigate if baking the WTR will reactivate surface sites, leading to a greater PO4 uptake. Batch isotherm and column experiments were performed to assess the specific adsorptive capacities. Numerous isotherm trials were planned to compare potential P adsorption within differing conditions. Variables may include different isotherm temperatures, static vs. dynamic desorption, and distilled vs. raw water desorption. The adsorption capacity will then be used to determine the variety of WTR best suited for P sequestration, identifying the amount that would be necessary to run a trial in a tributary flowing into original receiving source waters of the WTR material. Decreasing the P concentration entering the reservoir would aid in the prevention of harmful algal blooms.