If you've ever taken a drive along the banks of the Tamar River, you would be struck by two things - that the outlook to the estuary is stunning, and that thick swathes of rice grass overgrow the banks.
Rice grass was introduced in Australia in the 1920s and was planted on the banks of the estuary in the '40s, in a bid by the then-leaders of the state to make the estuary more habitable for large ships.
The impacts of that decision have been far-reaching, and the rice grass has taken root along the majority of the length of the estuary - on both sides of the river.
Invasive species expert Matt Sheehan completed his PhD on the impact of rice grass on the Tamar Estuary in 2008 and made several recommendations to the Department of Primary Industries, Parks, Water and Environment at the time to support its aggressive containment strategy of the invasive weed.
While unsightly for some, Dr Sheehan believes the time for eradication is far behind us.
"One of the things my PhD looked into was whether it was feasible to eradicate the rice grass and we found, ultimately, that it wasn't feasible," he said.
He said in 2008; rice grass incursions were apparent along with the majority of the length of the river. Today, Dr Sheehan says the incursion shouldn't be too much further along, but it would have become thicker.
Rice grass on the Tamar River has narrowed the channel and exacerbated the problem of sediment because the same amount of mud and silt is being moved by inter-tidal movements through a small area.
"Historically the estuary was muddy from Launceston to Windermere but further North than that it was a high tidal zone, so you found it was sandy and pebbly. Now, it's not, " Dr Sheehan said.
Our River - Exploring the health of the Tamar Estuary:
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- Chamber calls for independent body to oversee river cleanup
- Why the Tamar Action Group want more done to fix the river
- What scientists say about the health of the Tamar River
- Swimming in the Tamar near Launceston may never be safe
- 'We refuse to learn to love Tamar River's mud'
- Tourism operator says time for talk on Tamar is over
However, removal of the invasive species throws up more questions than answers, Dr Sheehan said.
One of the reasons rice grass eradication is nearly impossible is due to the weed's strong and long root beds that in some cases, can extend up to five-metres underground.
Dr Sheehan said the rice grass had also become a habitat for birds and fish, despite it not being a native species, so removing it would impact on the fragile ecosystem of the wetlands.
However, one of the main reasons that complete removal is not feasible is due to the cost and removal methods.
He said it could be done with machinery, but it was largely impossible to get machinery to the edge of the estuary or river banks.
Dr Sheehan said while some local community groups did do a manual removal of small patches in their communities, the Tamar estuary incursion of rice grass was the largest in Australia.
It is one of two large incursions in Tasmania, with the other on the Rubicon River, in the west.
"So if you don't have machinery removal at your disposal, the only other methods of removal is chemical, the impacts of which on the estuary would not be desirable on a large scale," he said.
Dr Sheehan said there were chemicals approved for use against rice grass, but it would be a bad look for the public to see councils or governments use chemicals in the river.
The only other way to remove rice grass is to smother it with black plastic, but then you had to contend with the root beds and other impacts.
An unexpected impact of rice grass is the build-up of mud and sediment - mud has been trapped by the weed on the banks of the river.
Removing the rice grass would allow that sediment to be pushed back into the water column - and would unleash sediment contaminated with heavy metals into the river.
However, he said containment of the rice grass, as undertaken by DPIPWE, was appropriate.
Water quality in the Tamar varies with each tidal zone, but the most contaminated and concentrated water found in the Launceston to Legana zone.
Dr Sheean said in his personal opinion there was much focus on the river and estuary now because more people were spending more time in the area.
"For many years, decades, the river has not been integrated well with the community, it was hidden behind a large wall [the levee wall]," he said.
"For the most part, the river has not changed, but for some people they see the mud and they don't like that, but there is a lack of awareness about what an estuary is. If you go down there at low tide and the sun hits the mud just right there is a beauty about it."
He said development in the estuary zone had heightened community expectations around what the estuary should look like.
The Examiner is running a campaign to raise awareness of the state of the Tamar River, by examining its health from different angles to educate the community on the state of water quality and other aspects.