Photo credit: Gary Spotswood

RESTORING WETLAND FUNCTION AT SPOTSWOODS LAGOON Spotswoods Lagoon is a 100ha shallow coastal wetland on farmer Gary Spotswood’s property, about 15km south of Home Hill, in North Queensland. Situated on the Burdekin Delta, it’s an important support area for the internationally-renowned wetlands of Bowling Green Bay. During flood events its waters flow into Cape Upstart and the Great Barrier Reef lagoon. The lagoon is a haven for many migratory wader birds, including the red-necked avocet, black-fronted dotterel, red-necked stint, and the endangered Australian painted snipe. But as recently as 2013, these birds, some of which travel from as far afield as Siberia, were nowhere to be seen – and around half the lagoon was covered with thick weeds, in particular Typha spp., commonly known as cumbungi.

Since 2013 NQ Dry Tropics has been running two separate projects concurrently – Systems Repair (funded by the Australian Government) and Landscape Resilience (funded by the Queensland Government), to restore the lagoon to its natural function. By combining these two key investments, NQ Dry Tropics has supported Gary to undertake measures including monitoring and reducing his water use, controlling weeds, and restoring the natural seasonal wetting and drying processes that prevent their return. NQ Dry Tropics worked closely with Gary and a range of project partners to identify the issues, develop solutions, and monitor progress – resulting in

excellent environmental and economic outcomes on his property. Spotswoods Lagoon is a success story that is influencing other landholders to adopt new practices, and serves as a guide for how to manage other similarly-affected wetlands in the Lower Burdekin.

CHANGES TO NATURAL LANDSCAPE FUNCTION For many years, water has been delivered to downstream cane growers via an irrigation channel adjacent to Spotswoods Lagoon. During periods of low demand, excess water would enter the lagoon via a spillway. Additional water would also enter via a spoon drain that was receiving tailwater from two neighbouring cane paddocks. The lagoon had become permanently wet, instead of naturally wetting and drying according to the season. This had created ideal conditions for native and exotic species to flourish. This proliferation had reduced migratory wader bird habitat and numbers, as well as fish populations that are unable to swim through the dense thickets. The cumbungi was also providing habitat for feral pigs, and creating artificial conditions for native Eurasian coots to thrive, which was damaging adjacent sugar cane crops. The combination of weeds stripping oxygen from the lagoon, and nutrient-rich water entering from the cane paddocks, led to a serious decline in water quality. This was a particular risk to downstream

Australian painted snipe. Photo credit: Len Ezzy seagrasses, turtles and coral whenever the lagoon overflowed during flood events.

RESTORING NATURAL PROCESSES Managing this problem required a strategic approach, and its success depended on Gary agreeing to participate in both projects. NQ Dry Tropics’ Senior Project Officer, Scott Fry explains : “The ‘Systems Repair’ project aims to improve the ecological function of priority coastal wetland ecosystems. We spent this funding primarily on weed control, protecting and

Red-necked avocets. Photo credit: Gary Spotswood enhancing wetland and riparian vegetation, managing pests, and restoring the landscape’s natural seasonal wetting and drying cycle.” “The ‘Landscape Resilience’ project focuses on helping to restore wetlands and waterways in the Lower Burdekin region by raising awareness and encouraging irrigation practice change among cane growers, through on-farm water monitoring. This funding helped Gary to monitor the quality and quantity of water both leaving his farm and entering it from adjacent farms,” he says.

SYSTEMS REPAIR Under this project, Scott engaged with Gary, Charlie Papale (from local irrigation provider Lower Burdekin Water - South) and adjacent landholders to discuss the current impacts of invasive species, agree on potential activities to fix the problem, and, crucially, establish exactly what the wetland was being managed for. Scott explains: “It was important to agree on a management objective for the lagoon. Some years ago following a fish kill in the area, some locals had asked the water board to try and keep the lagoon full at all times to create permanent fish habitat. This had the unintended consequence of supporting weed growth.”

“Our discussions identified some large, deep holes in the middle of the wetlands that would provide enough dry season refugia to sustain most of the fish populations, and any fish kills would be localised events. We resolved to monitor the condition and water levels of the wetlands at critical times of the year when fish kills may occur, so they could be rescued and relocated.” Following this engagement process, a joint decision was made to reinstate seasonality to sustainably control weeds without using herbicide and mechanical means. NQ Dry Tropics and Lower Burdekin Water established an agreement to conduct remediation works that would: • reduce supplementary irrigation water entering the wetland; • reinstate seasonality; • return shallow water habitat for wader birds; • monitor how long the area needs to seasonally dry out to control invasive species; and • monitor changes to migratory bird populations (undertaken by BirdLife Townsville).

LANDSCAPE RESILIENCE Gary was one of 65 farmers who signed up to the Landscape Resilience project. He got involved because he wanted to know how much water he was losing to run-off, and what nutrients the water contained. He says: “Any water and nutrient lost to the downstream environment is money lost to me – I want to keep it on my property, and if I’m wasting any I want to know so that I can do something about it!” The project team monitored the quality and quantity of water entering and leaving Gary’s farm. A data star flow logger placed in the spillway at the irrigation channel measured how much irrigation water was entering the lagoon. During one overtopping event it recorded approximately seven megalitres a day. Following consultation with Lower Burdekin Water, the spillway was raised and measures taken to reduce the amount of unnecessary water being delivered through the channel. Since these changes, there have been no instances of excess water overtopping and entering the lagoon.

“We knew that restoring the natural wetting and drying cycle could lead to occasional fish kills, and it was important for everyone to understand that these events are part of the natural process, and they are a beneficial nutrient exchange between fish, birds, and riparian vegetation. It was also agreed that if no action was taken to tackle the current weed growth, in a couple of years there wouldn’t be any fish habitat left.”

A peak overflow event from the irrigation channel into the wetland.

ONGOING MONITORING After a year, monitoring indicated that water levels hadn’t reduced as much as expected, and the lagoon wasn’t sufficiently drying down. The project team turned its focus to another possible culprit – the shallow spoon drain on the opposite side of the lagoon that was receiving tailwater from two landholders’ paddocks. This small drain had originally been identified as a source of discharge water, but Gary had considered it to have minimal impacts on the lagoon levels. Due to the cost of capturing and reusing this water, the team had chosen to monitor the impact of the closed spillway first, before deciding whether it was justifiable to spend time and resources on the spoon drain. The team decided to deploy the data star flow logger to measure the flow through the drain. The results were clear – one megalitre a day was entering the lagoon – far more than anticipated. NQ Dry Tropics then contracted Burdekin Bowen Integrated Floodplain Management Committee (BBIFMAC) to monitor the drain with different equipment to ensure accuracy. Gary was amazed: “Until I got the results from this project I had no idea just how much water I was losing to run-off,” he said.

Figure 1: Water volume run-off monitoring results from irrigation event in July 2015. The lagoon and surrounding wetlands now successfully dry down and are returning to their natural processes. Cumbungi is dying back and if weather conditions permit, Gary will burn these areas to accelerate the process of returning to an open water habitat. Because the lagoon dries down, it forms a natural retention basin that captures the nutrient-rich first flushes of run-off when the rains arrive. This protects the Reef downstream from an influx of poor quality water. A native macrophyte, Schoenoplectus subulatus, commonly known as rice field bulrush has also returned and formed a monoculture. This plant provides ideal habitat for macroinvertebrates, frogs

and fish, and in turn supports the food web as well as filtering nutrients out of the water. It also provides important habitat for the Australian painted snipe. Scott says: “The results of this monitoring are guiding future investment that will lead to long-term economic and ecological benefits. There has also been enough compelling evidence to influence landholders to adopt new practices to ensure the ecological health of this wetland will be improved and sustained. The results have been so successful that NQ Dry Tropics intends to use Spotswoods Lagoon as a demonstration site to guide how to manage other wetlands in the Lower Burdekin experiencing similar issues.”

The project team and Gary discussed options to capture and reuse this excess water, and agreed to co-invest in a recycle pump, with Gary contributing $32,000. The pump would operate in a minimum depth of 300mm and capture all water leaving the paddock, preventing it from entering the wetland and enabling it to be reused on the farm.

RESULTS The co-investment in the pump is already proving to have dual benefits. During a six-month period, Gary has recycled around 150 megalitres of water for use on the farm. Within three to four years Gary expects to balance out the cost of the pump against the cost of purchasing water. He also expects additional income from the crops that can be grown on the now drought-proof 10ha block.

The eight inch pump delivers water to a 280mm poly pipe which is 500m long. This pipe has three outlet valves that allow Gary to distribute water where required on his property. The outlets service three different areas for different agricultural uses. The furthest outlet location has a dual benefit; it allows the water to irrigate pastures across 400m of beef grazing paddocks, before ending up in a sugar cane recycle pit. This additional water supply allows Gary to grow a crop on a 10ha paddock that would otherwise sit fallow in failed wet seasons. Prior to installing this pipe, Gary required a minimum wet season rainfall of 250mm to enable him to irrigate this block. The other two outlet valves supply water to his farm dam, which he uses to water stock and irrigate additional paddocks.

Gary says: “ With the success we’ve seen on the ground throughout this project, I’m already starting to think about the next thing we can do. It’s really opened my eyes to all of the possibilities.” “I have introduced more crop rotations, minimised the amount of cultivation, changed my water scheduling and I’m progressing towards more efficiently recycling irrigation run-off water. This benefits the nearby wetlands and coastal creek systems downstream of my farm. Better irrigation management also means I can apply less water, which saves money on pumping costs.” NQ Dry Tropics Project Officer Lisa Pulman adds: “ This demonstrates how oneon-one engagement, building trusting relationships, and effective monitoring can successfully drive practice change and result in positive environmental outcomes.”

Gary uses recycled irrigation water from the wetland to irrigate beef grazing pastures, with the remainder flowing into a recycle pit.

The Australian Government’s “Restoring Burdekin Coastal Ecosystems for the Great Barrier Reef and Ramsar (Systems Repair)” project is funded through the Reef Programme’s Biodiversity Fund.

Black-fronted dotterel. Photo credit: Len Ezzy

The Queensland Government’s, “Improving Landscape Resilience in the Important Sugar Production Area of the Lower Burdekin Delta (Landscape Resilience)” project is funded through the Queensland Regional Natural Resource Management Investment Program.

WHO ARE WE? NQ Dry Tropics is an independent, not-for-profit, non-governmental organisation that supports the Burdekin Dry Tropics community to sustainably manage its land and water. Established in 2000, we enjoy excellent relationships with community groups, landowners, local and national industry bodies, and all levels of government. HOW DOES NQ DRY TROPICS HELP PROTECT WETLANDS? NQ Dry Tropics works with the community to help improve understanding and awareness of water quality and land management issues. We encourage practice change, and promote the benefits of restoration and revegetation. We work with many stakeholders, including utilities, cane growers, and other landholders in the region to help identify and manage priority wetlands so that they function as they should. FOR MORE INFORMATION For more information, please visit our website at: www.nqdrytropics.com.au; or contact a staff member from the NQ Dry Tropics’ Waterways, Wetlands and Coasts team on 07 4724 3544 or email [email protected].

TEL 07 4724 3544 I 12 WILLS STREET TOWNSVILLE CITY 4810 I WWW.NQDRYTROPICS.COM.AU