Department of the Legislative Assembly, Northern Territory Government

Sampan and Tommycut Creeks

9th Assembly


149. Sampan and Tommycut Creeks

Mr Wood to MINISTER for Lands and Planning

1. The Territory government has spent millions of dollars trying to keep the sea out of Sampan and Tommycut Creeks, for how much longer does the government plan to keep funding and fighting this battle.

Hide details for ANSWERANSWER

Answered on 31/08/2004

1995, the Northern Territory Government has expended $5.150m through Capital Works program funding on a major salt water intrusion control program on the Mary River. This program was instigated following a major review into multiple use of wetlands by the Sessional Committee for the Environment and the development of a Mary River Integrated Catchment Management Plan earlier in that year. This work is not keeping the sea out of Sampan and Tommycut Creeks which are tidal channels, but preventing the expansion of new saltwater channels into freshwater wetlands on the Mary River floodplains.

Over 24 000ha of previous freshwater wetland environment have been affected by saltwater intrusion, and the potential for 100 000ha of freshwater floodplain to be converted to tidal dominated salt flats is high.

As a result of works to date, 8000ha of the previously inundates floodplain have been protected and are now recovering. The recovery of areas of melaleuca forest and other freshwater areas in the Mary River conservation reserve has shown that mitigation actions are effective. In 2003, a cost benefit analysis of the Mary River salinity mitigation works was undertaken, and this study found that there were significant net benefits from addressing salinisation in the Mary River.

The work in the Mary River to prevent saltwater intrusion is pioneering new techniques that have been largely untested elsewhere in the world. Numerous engineering consultancies have examined the problem and the current strategy of constructing submerged weirs within the two major creek of Sampan and Tommycut has come about following a review and investigation by Delft Hydraulics Laboratory in the Netherlands. The submerged weirs reduce the tidal amplitude and decreases the ability for new channels to erode upstream of these structures, thereby protecting large areas of freshwater flood plain.

In November 2002, the Northern Territory Government signed a Bilateral Agreement with the Australian Government to take part in the national Action Plan for Salinity and Water Quality
(NAP). Funding is provided on the basis of the Northern Territory Government matching the Australian Government on a t dollar for dollar basis for new funding. As a result, the Northern Territory Government has agreed to provide $0.5m per annum from 2003-04 to 2006-07 as the Northern Territory contribution to the NAP. Effectively, this halves the cost to the Northern Territory of conducting saltwater intrusion works in the Mary River. However, this commitment is reviewed annually in order to ensure that success has been achieved with this investment.
Last updated: 04 Aug 2016