Grahamstown Dam

Constructed between 1956 and 1965, Grahamstown Dam is the Hunter’s largest drinking water supply dam. It supplies more than half of the drinking water our customers use on a regular basis, even more during periods of drought and peak demand.

It’s an off-river storage source that extracts water from the Williams River and receives inflow from its own catchment.

Grahamstown Dam
Catchment area 97km2
Dam volume 182,305ML (million litres)
Average depth 9 metres
Surface area 2800 hectares
Annual rainfall 1125mm (Williamtown)
Areas supplied Lower Hunter, approximately 40% of volume
Land use breakdown of catchment 39% Hunter Water freehold, 39% rural, rural residential or urban, 22% State Forest.

Grahamstown Dam risk assessment report

Grahamstown Dam main embankment

As part of our commitment as a responsible dam owner, we've just finished our most detailed risk assessment ever completed for Grahamstown Dam.

Our current storage levels

Our water levels drop faster than most other major Australian urban centres during hot, dry periods because we have shallow water storages and high evaporation rates.

The catchment

The catchment is primarily located on the northern and eastern shores of the dam.

To the north of the catchment, Seven Mile Creek fills the dam with run-off from small farms and other minor developments. Approximately 75 per cent of total catchment run-off comes from the northern part of the catchment.

Run-off from the east comes directly from the urban settlement of Medowie through the Campvale Swamps. Water is pumped into the dam via the Campvale Pump Station and finally spills at the Irrawang Spillway.

We work closely with landowners and residents in the Grahamstown catchment area to improve the quality of water draining into Grahamstown Dam.

Aerial photo of Grahamstown Dam showing water and constructed embankment (dam wall).

Transfers from the Williams River

Grahamstown Dam is classified as an off-river storage facility, storing raw water that’s pumped from the Williams River at Seaham Weir through the Balickera Canal, raised approximately 15m at the Balickera Pump Station and then flows through the Balickera Canal and Tunnel into the northern end of Grahamstown Dam. On average, 50 per cent of inflow to Grahamstown Dam is pumped from the Williams.

We monitor water quality in the Williams River for nutrients before transferring water to Grahamstown Dam. Like most Australian rivers, the Williams is highly influenced by climatic conditions and is consequently highly variable in flow and water quality. Flow and water quality are assessed against pumping rules to minimise the nutrient load transferred to the dam.

How it works

  1. Seaham Weir is used to separate the downstream tidal estuarine salt water from the upstream fresh water.
  2. Balickera Pump Station and Canal are used to transfer water from the Williams River to Grahamstown Dam. The station is designed to transfer flows from the very high flow periods that would otherwise just make their way out to sea.
  3. Water stored in Grahamstown Dam is accessed for supply to customers at George Schroder Pump Station. This pump station delivers water through twin parallel mains to the Grahamstown Water Treatment Plant at Tomago. All water from Grahamstown Dam is fully treated before distribution to customers.

Finnan Park picnic facilities

Finnan Park is located at the southern end of Grahamstown Dam off Richardson Road and has picnic facilities overlooking the dam. Facilities include parking, water taps, toilets, children's playground, picnic shelters and picnic tables. Private bookings of the Finnan park facilities are not available.

Finnan Park opening hours

Finnan Park is open during daylight hours only. The gates are locked overnight.

Public access

To protect drinking water quality, public access is not permitted onto Grahamstown Dam or its catchment, but there is an adjacent picnic facility that is open to the community.

Celebration of Aboriginal culture on display

We recently revealed a mural at our public recreation area at Grahamstown Dam, with the Aboriginal artwork highlighting our community’s deep connection with water.


As the dam is a drinking water supply source for the Hunter Region, there are restrictions in place for visitors to Finnan Park. These include:

  • No dogs, horses or other pets within the picnic area
  • No camping or staying overnight
  • No swimming or entering the waters
  • No boating or fishing


The penalties for non-compliance and further information can be found on the Public access to dams and catchments page.

Further information

For further information on the park, please contact us on 1300 657 657.