What are you doing about water quality in the Estuary?

The $140.7 million River Health Action Plan is focused on improving the health of the kanamaluka/Tamar Estuary through infrastructure upgrades and better catchment management. Work is currently underway on this program.

The draft vision is focused on priorities that improve the community’s experience of the kanamaluka/Tamar Estuary in sustainable and innovative ways. The priorities in the draft vision will complement other ongoing work to improve water quality and river health, including the River Health Action Plan.

Find out more: Water Quality

Why does the mud seem to be worse than it used to be?

Many people believe that the mudflats around Launceston are a recent issue of the estuary, and that sediment is ‘worse than it used to be’. However, accounts from the earliest European explorers to visit the upper kanamaluka/Tamar Estuary show that this area has always featured extensive mudflats and wetlands.

Of course, there have been lots of changes around the estuary since European arrival. Wetlands fringing the estuary have been filled in and levees have been constructed to protect low-lying areas. Measurements going back to 1889 tell the story of changes in the shape of the estuary. At that time, the channel was narrow and shallow with large areas of visible mudflats above the mean low tide level. When the upper estuary was extensively dredged from 1936 and 1957 to allow the passage of large ships, recorded depths show a deep and wide channel.

However, changes brought about by dredging are only temporary, as sediment quickly returns to pre-dredging levels. It’s important to remember that the interventions of the past were often associated with large environmental impacts that would not be possible today under Australian and/or Tasmanian environmental protection legislation.

Smaller scale dredging programs continued to be carried out from the mid-1980s to 2010. After the dredging was stopped, the upper estuary has returned to something closer to its 1889 shape. However, the channel is deeper than it was at the turn of the century, most likely because flows are now constrained on both sides of the estuary by infill and levees.

While the tidal mudflats have always been a natural part of the estuary, there’s no doubt the estuary around Launceston has changed indefinitely by the infilling of wetlands and construction of levees. This is why it is important that we understand the impacts of any changes to the estuary going forward.

What are you doing about the sediment in the Estuary?

The draft vision consists of two priority areas to improve the community’s access, use and enjoyment of the estuary.

One of these priorities considers the long-term management of sediment in the estuary. It explores options for restoring public wetlands to reduce the accumulation of sediment in the North Esk, Seaport and Home Reach. Further information on this option can be found here in the evaluation report.

These options will be discussed with the community and key stakeholders, who will have the opportunity to learn more about the proposed interventions and have their say on future actions to address sediment.

Find out more: Sediment Management

Why can't we use sediment as top soil?

Sediments in the upper estuary trap heavy metals and other pollutants. This makes them potentially unsafe for use on farms or gardens as topsoil.

These sediments are also potentially acid sulfate which means that when they come into contact with air (eg. by being removed from the estuary) they can release sulfuric acid and must be treated to avoid harm.

Find out more: Sediment Management

Why can't we dump the sediment out to sea?

Waters surrounding Australia's coastlines (beyond 3 km of the coast) are protected from wastes and pollution dumped at sea by the Environment Protection (Sea Dumping) Act 1981. The dumping of dredge spoil is a heavily regulated activity under this legislation and would require a Sea Dumping Permit from the Australian Government. Due to the likely impact on the marine environment of contaminated soils, a permit might not be granted.

Dumping dredge spoil in the estuary or closer to the coast would require environmental approvals under state legislation to ensure it doesn’t negatively impact on water quality.

Large-scale, ongoing dredge programs could be expected to have very significant environmental impacts if dredge spoil were to be dumped within the estuary so it is unlikely permits for in-estuary dumping for such dredge programs would be granted.

What other options are there for dealing with the sediment?

In 2020, the Tamar Estuary Management Taskforce commissioned the Tamar Estuary and Esk Rivers (TEER) Program to conduct an independent and comprehensive evaluation of options to address sedimentation.

The scientists looked closely at different options for the management of sediment in the kanamaluka/Tamar Estuary. Many of these options have been the subject of public debate or conjecture in recent years.

The options considered were:

  1. No intervention
  2. Accelerated restoration of intertidal habitat
  3. Restoration of wetlands and the tidal prism in the North Esk
  4. Dredging of the upper estuary
  5. A Tailrace canal
  6. Increased flows in the South Esk
  7. Barrages and weirs
  8. Sediment raking
  9. Various concepts proposed by stakeholders.

Although the report does not make any recommendations, it considers the technical feasibility, indicative costs, social benefits, and environmental impacts of each of the options. Based on the evaluation report, the Taskforce developed a draft vision for the management of the kanamaluka/Tamar estuary. The draft vision identifies elements from the third option - namely restoration of public wetlands and more active management of informal levees and infilling of wetlands - as an achievable way to reduce sediment, while also providing broad community and environmental benefits.

Find out more:

Are mudflats a flood risk?

As an estuarine city situated around the meeting of major rivers, the area of Launceston has always been prone to flooding.

Much has been done over the years to manage this flood risk, including the construction of weirs and levies. Large floods rapidly move substantial amounts of sediment out of the channel and surrounding mudflats. This means that pre-flood levels of sediment have little to no impact on flood levels. The best available evidence suggests that sedimentation is likely to lead to, at most, small increases in flood levels for smaller floods and that these changes are unlikely to pose a significant flood risk to Launceston given the flood levee system that is already in place.

Find out more: Mudflats

Why are you consulting?

We believe the kanamaluka/Tamar Estuary can be an inspiring public destination that:

  • brings people to the water’s edge
  • connects key areas of the city and regions
  • includes new cultural and recreational precincts
  • celebrates the environmental values of the estuary
  • enhances opportunities for businesses and tourism.

To help realise this vision, we are inviting you to tell us what you value most about the estuary. We want to understand how people use the estuary, and make sure we are on the right track with the draft vision.

We’re asking you to share your ideas about how we can transform the upper estuary region around Launceston into a significant cultural and recreational destination for everyone to access and enjoy.

Read the draft vision: Draft vision for the future of the kanamaluka / Tamar Estuary

What will happen to my feedback?

Once the community engagement is completed, we will develop the vision and present options to the Tasmanian Government for consideration. These options will help guide future planning and decision-making for the kanamaluka/Tamar Estuary.

Updates will be published on this website, or you can register your details with us to stay informed.

Register your details

Can you explain the sewerage system in Launceston?

The term sewerage refers to the networks and sewage is the contents. The sewage treatment plants are generally referred to as wastewater treatment plants.

Greater Launceston has six sewerage treatment plants, which receive sewage from household and commercial settings and, following treatment, dispose into the Estuary.

However, Launceston's main treatment plant Ti Tree Bend receives sewage and stormwater from a combined system of sewage and stormwater pipes.

The combined system is designed to take sewage and stormwater to the Ti Tree Bend wastewater treatment plant, but during heavy rainfall the volume of stormwater exceeds the capacity of the pipes and the system is designed to overflow into the waterways. This is important so that sewage doesn't overflow into people's houses. The combined system was upgraded in the 1960's to handle the increasing volumes of sewage and stormwater associated with increasing development. While some might think that separating the system is the best solution, it is neither practical or feasible and the same improvement in estuary health can be achieved by upgrading the combined system that it doesn't overflow as often.

While Launceston's combined sewerage and stormwater system may be unique in Tasmania, many of the major cities in Europe, the USA and Asia have combined systems. It should also be noted that while the combined system is considerable, there is much of the city which operates on a separated system. ‘Unfortunately, the combined system is in the oldest and most built-up areas of the city, which constrains how easily the systems could be separated.

Find out more: Catchment Management

What are you doing about dredging?

All queries about dredging should be directed to the Department of State Growth – please email info@stategrowth.tas.gov.au.