With its location in the rainforest and in an environment that receives nearly 5 meters of annual rainfall, water management is one of the critical technical challenges for Minera Panama. ERC was brought into the project due to its experience characterizing and developing water management plans for mines in locations with extreme climatic conditions. Our first task was to establish estimates of design rainfall events and associated runoff for short-term and extended wet cycle conditions. Our next challenge was water diversion. The main local river, the Rio Botija, ran right through the initial mining target and needed to be diverted around the planned pit. ERC’s design included a risk based assessment of tradeoffs between design storms and allowable pit flooding. The ultimate design required lining to minimize seepage and related instability adjacent to the pit wall for the 2 kilometer channel. Finally ERC developed an operational water balance model for mine personnel use in managing pit sumps and surface water dewatering systems.