The KA +/- AYladag gold mine (UAYak, Turkey) has operated since 2006 and is projected to close by 2030, leaving a large open pit. We quantified dewatering requirements during the operational period, predicted pit lake formation during the post-closure period, and assessed the likely impacts on groundwater resources. Groundwater inflow into the pit during 17 years of mining was calculated using analytical and numerical models. The analytical model yielded lower inflow rates because it does not account for groundwater that will be released from storage. Post-closure, pit lake water balance calculations show that the system will reach equilibrium 585 years after dewatering ceases and that lake levels will stabilize at 816 m above sea level (masl). Further analysis indicated that 830 masl is a critical level, below which the pit will behave as a sink; above that, it will be a flowthrough system that could possibly affect downgradient groundwater quality.