Balranald Weir Fishway
Murrumbidgee River
Mollee Weir Fishway
Namoi River
Yarrawonga Weir Fishway
Murray River
Fishway - Lock
Lock fishways are used on high level weirs greater than 6 metres. Lock fishways operate by attracting fish through an entrance similar to other fishway types, but instead of swimming up a channel the fish accumulate in a holding area at the base of the lock.
This holding area is then sealed and filled with water to reach a level equal to the water upstream of the barrier. Fish are then able to swim out of the lock.
To encourage fish to move through the various attraction and exit phases of the lock cycle, a combination of attraction flows and crowding screens can be used.
Case Study – Mollee Weir Lock Fishway
The original Mollee Weir was constructed in 1973 for irrigation, effectively blocking fish passage in the Namoi River system. As part of the Water NSW Dam Safety Upgrade Fishway Offsets Program, an agreement was reached to provide fish passage at Mollee Weir in lieu of high level fishways at Keepit and Split Rock Dams. The objective of the Molleee Weir Fish Lock was to provide a facility to restore fish passage of adult and juvenile fish. The new fish lock was constructed in 2014 with the design featuring a fish lock for upstream migrating fish and a dedicated overshot gate with dissipating pools for downstream migrating fish.