Noosa on Queensland's Sunshine Coast is renowned for its fine food, beautiful beaches, national parks and its pristine network of waterways that form one of only two everglade systems in the world, the other being in Florida.
But the battle continues to halt millions of tonnes of soil washing down from its upper catchment, which forms layers of sediment that smother aquatic life downstream.
Like dozens of other landholders, graziers Jeanette and Bruce Glasby are working with Landcare to remediate the legacy of past land use, when the rural town of Kin Kin's steep hills were clear felled for timber and farming.
Seven large landslips opened up after flooding this year on the Glasby's farm, which the family purchased in the 1930s.
"It's a challenge. Wahpunga Creek goes right through our property, right from the quarry up the other end, and we have fenced half of the creek off."
In 2008 and 2015, the Kin Kin catchment was surveyed using LIDAR — a near-infrared laser that maps land elevations from the air.
In that seven year period the hillsides shrank — more than 2.4 million tonnes of soil had mobilised.
The cost of that topsoil loss was estimated to exceed about $74 million, based on the average soil replacement cost of $30 a tonne and the area's resulting productivity decline.
Rachel Lyons from Noosa and District Landcare said that for a small catchment area of about 20,000 hectares the amount of soil that had moved was significant.
The environment has also paid a price each time sediment washed down into the shallow Lake Cootharaba and the Noosa river system.
Floods contribute to topsoil loss
Aerial photos shared by Queensland's Premier Annastacia Palaszczuk after this year's flood showed brown plumes of sediment as they surged into the ocean near Noosa's famous Hastings Street.
A long-term comparison of four sites along the estuary revealed up to a 65-per-cent decline of benthic species in 20 years.
Benthic species are the tiny worms, snails clams and crustaceans that live in the mud and sand that provide food for the fish and crabs targeted by commercial and recreational fishers.
The costly LIDAR surveys have not been repeated, but a mountain of work continues to address the cause.
Keeping it in Kin Kin
Landowners, Noosa council, and Noosa and District Landcare are among many groups working on 'Keeping it in Kin Kin', a project aimed at keeping precious topsoil in place.
John Day from Emu Ridge consulting was the key speaker at a workshop organised by Noosa council.
"The next thing is looking at where your infrastructure is, where your fences are, where your roads are, because all those things normally create problems. They channel water and can lead to gullying, so if you get your infrastructure in the right place then you're in great shape."
Noosa and District Landcare's project officer for "Keeping it in Kin Kin", Jamie Knight works with landholders to revegetate erosion-prone gullies and creek lines, in part by planting out thousands of trees.
He works to re-establish growth corridors by connecting old vegetation and riparian corridors with new plantings.
"I would be looking at some very fast-growing tap-rooted trees such as Acacia melanoxylons, Grevillia robusta, the silky oaks [and] the black wattles; which are very fast growing and have deep-growing roots," Mr Knight said.
Mr Day also recommends seeding bare soil, creating better creek crossings, and providing off-creek watering points for stock.
