LADWP has been asked by the California Water Quality Control Board to reduce or eliminate copper treatment in North and South Haiwee Reservoirs. As a result of this request, LADWP asked Flow Science to perform a detailed analysis of the mixing processes in Haiwee Reservoir to determine the fate of the applied copper. The work included extensive data analysis, as well as one and three-dimensional hydrodynamic and water quality modeling. In particular, the 3-D model ELCOM was set-up to determine the mixing patterns in South Haiwee Reservoir, where the transport processes are impacted strongly by stratification and severe wind mixing. Flow Science evaluated the impact of mixing on the fate and sedimentation of copper in the reservoirs.