Water management was a significant challenge at the El Sauzal mine given the site’s steep topography and flashy rainfall history. ERC was retained to develop a diversion and water management plan for the mine’s closure. Site and historic regional precipitation records were evaluated to define the magnitude of rainfall expected at various frequencies. A risk assessment was completed to consider flow frequency and facility sizing. Based on this analysis the mine selected the 100-year storm event for design. ERC’s design included over six kilometers of channel. Design also included sediment ponds, energy dissipation structures, stilling basins and rundowns. Due to the varied flows, slopes and ground conditions a number of types of channel armoring were required with armoring including vegetation, bedrock, concrete and geowebs.