The 91m high Geehi Dam is a rockfill type with an earth core impervious to
water. It forms this 21 GL reservoir which is the head storage for
Murray 1 Power Station. Due to limited space in the narrow Geehi River valley a bellmouth spillway was built, the second in Australia.
Water enters the reservoir at up to 150 cumecs via the Snowy-Geehi tunnel plus minor local stream flow diverted in by aqueducts. As electricity is generated in Murray 1 and 2 power stations,
water flows out of Geehi at 250 cumecs during the morning and evening peak. Inflow via the tunnel occurs at any time to keep the dam as full as possible, ready for generation.