A new high-frequency water-quality monitoring station has recently been installed at Corduroy Creek south of Tully. It’s the eleventh for the Tully-Innisfail region and it’s in one of 50+ locations where water monitoring has been happening in paddocks, drains, creeks and rivers across the Tully, Murray and Johnstone River catchments.

Why do we do it and how does it help farmers?

We’re helping farmers to sustainably manage their land. The data is giving all of us a better understanding of how human activities, including land management practices, impact waterways and the Great Barrier Reef. We design water monitoring programs to answer landholders’ questions about water quality. The data is shared with participating landholders and industry bodies. It has led to changes in the way farmers use pesticides and fertiliser, and manage ground cover. Having more knowledge and understanding = good decision making.

Why Corduroy Creek?

Cane growers in this area asked for data. So this creek has been monitored for more than six years now, initially through a project run by Sugar Research Australia and then through two Terrain NRM projects. We chose the same monitoring sites so we can look at trends over time. With long-term datasets, we can track changes in water quality following changes to land management practices. This helps us all to see the effects of different practices and the way changes can make a positive difference to water quality.

How do high-frequency water monitoring stations work?

These stations fill in the gaps between monthly water sampling results. Every half hour, a nitrate sensor takes a measurement. By measuring stream flow as well, we can see changes in nitrate concentrations and we can also calculate the nitrate load moving down the creek (in kilograms) during a single rain event, during the first big flush of the wet season or for an entire year. The new station at Corduroy Creek also has a rain gauge, to help us relate the stream flows and nitrate concentrations to rainfalls, given how localised rain can be.

More than 140 people have been part of community workshops focused on the next 10 years of investment in water quality improvements for the Wet Tropics region’s nine river catchments.

From Cardwell to the Tablelands and Cairns, workshops have brought together landholders, industries, traditional owners, river catchment groups and local government. Workshops are also happening further north, in Mossman and the Daintree region, in coming months.

New strategy to guide investment in water quality programs

Terrain NRM’s Charles Hammond said the sessions would help to guide strategic investment in land-based water quality programs over the next decade. Terrain is being funded through the Australian Government’s Reef Trust program to lead the development of catchment priorities.

Identifying regional priorities

“In the workshops, we’ve been identifying regional priorities,’’ Charles said. “We’ve also been looking for opportunities that’ll maximise investment by delivering multiple benefits to the environment and local communities.

“The response has been great. People are telling us how useful it is to talk with other industries and groups, and to share information about a wide range of past, current and future projects and resources.

“They’re seeing just how many organisations are working towards improvements for river catchments and water quality, and the value of working together.”

He said a huge amount of effort and investment had already gone into improving reef water quality over the last 15 years, and good progress had been made.

“There has been significant work with landholders on farm management practice changes to improve everything from the land and production to the quality of water leaving properties.

The rootballs of trees are part of a new engineered solution for erosion along the Herbert River near Ingham.

About 180 metres of flood-damaged riverbank has been repaired using five rootballs combined with more than 2000 tonnes of rock – for a rockwall with a difference.

Strengthening riverbanks, creating fish habitat

Terrain NRM’s Lana Hepburn said the result would both strengthen the riverbank and create fish habitat.

“The hardwood is wedged trunk-first into the lower riverbank so the rootballs are in the water, with rock benching holding them in place,’’ Lana says.

“The rootballs add complexity to the waterway, creating eddies and different flow rates which moves the fast-flowing water away from the toe of the streambank to prevent more erosion. They also create places for fish to rest and feed.

Erosion since 2009 wet season

She said the riverbank had been eroding at the site since 2009 and the 2021-22 wet season had worsened things, with more riverbank vegetation lost to flooding.

“Since 2009, the riverbank has retreated 20 to 40 metres on average across the site. The toe of the riverbank – the point where the riverbed meets the bank and supports the weight of the bank –became completely unvegetated. So when the 12 metre high bank was hit by fast water, it was eroding at the toe and collapsing, sending soil down the river and fine sediment out to the ocean.”

Cane farmer Mark Zatta, whose land borders the river, says he’s “stoked”.

“Originally we had about 50m of rainforest along the river but we were losing it over time. All of a sudden, in one river rise, a whole lot was gone. Once the first wall (of riverbank) dropped, it just kept collapsing. It’s on the outside of a bend in the river where the river pushes around.

A new $3.2 million project will focus on the Herbert catchment – the largest river system in the Wet Tropics which begins on the Atherton Tablelands and flows to the ocean almost 300km away at Ingham.

Workshops with a wide range of representatives

Terrain NRM is working with a wide range of industries and groups to plan for the Herbert Integrated Project, which is funded through the Queensland Government’s Queensland Reef Water Quality Program. More than 40 people have been part of workshops in Ravenshoe and Ingham recently to help determine the best actions to further improve water quality, the land, its resilience, agricultural outcomes and co-benefits for the local community.

Whole-of-catchment approach

Project manager Fiona Barron said a whole-of-catchment outlook was important.

“We will be building on previous projects in this catchment. They include working with farmers on grazing and sugar cane management practice changes to improve everything from the land and production to the quality of water leaving properties. They also include fine-scale water quality monitoring, constructing fishways and repairing streambanks by engineering structures like rock chutes and pile fields.

Building on solid results from previous projects

“Programs delivered over the last 15 years have made good progress. But to meet the 2050 water quality targets, we need to build on past work. This new Herbert project will draw heavily on local knowledge, combined with all the data and science that’s come before, for a program that’s tailor-made to the upper and lower Herbert.