Seaham Weir, which is located on the lower Williams River near
Seaham, is used to separate the downstream tidal estuarine salt
water from the upstream fresh water. The weir structure includes
a fishway for fish migration, and gates that are used to control
the upstream water level. The canal intake is located
immediately upstream of Seaham Weir at Boag’s Hill and includes
a radial gate, trash rack and a water quality monitoring
station. Balickera pump station and canal are used to transfer
water from the Williams River to Grahamstown Dam. This
conveyance system includes around 5 kilometres of canal and a
pump station part way along that lifts the water around 15
metres. The decision of when to pump water is based on
availability of water in the river, space in the dam, and the
quality of the water in the river. Pumping is suspended if
nutrient or algae cell levels at Boag’s Hill intake exceed pre-
determined limits. While the average flow in the Williams River
is around 1,000 megalitres per day, the distributi