The North Central Catchment Management Authority (CMA), in partnership with Goulburn-Murray Water, is currently undertaking works to control the Pale Yellow Water Lily (Nymphaea sp) on Gunbower Creek and associated lagoons.   

An introduced species, which is characterised by its heavy green foliage and pale yellow flowers, causes problems by blocking waterways and impacting on irrigation and recreational use.  It rapidly colonizes shallow, nutrient-rich waters resulting in dense infestations that restrict water movement and contribute to siltation of the creek.   

According to local residents and Trent Gibson, North Central CMA’s project manager, infestations of the plant have increased dramatically over the past few years in the creek.  “Several local groups, including the Gunbower Creek Weed Reference Group, have raised this as being one of the local residents’ major concerns.  

“Despite the plant being present in Gunbower Creek for over 20 years, we have noticed increasing infestations.  Once established, this invasive weed can be difficult to control.  We suspect the increased nutrient levels, water temperatures and low irrigation draw down due to drought impacts are contributing factors to the proliferation of the Pale Yellow Water Lily.”   

Mr Gibson said treatment methods would follow recommendations from recent trials, including the use of aquatic approved glyphosate and spraying during the active growth period of November-April, with a second treatment in March.   

“We intend to control the infestations, between the National Channel off-take and then downstream to the Cohuna Weir, by gradually treating strips along the centre of the waterways, first and pushing outwards towards the shoreline.  Following herbicide application the decaying plant matter will be carefully monitored by installing dissolved oxygen probes to reduce the risk of a blackwater event.  Unfortunately it will require several years of repeated treatment, with significant monitoring and evaluation vital to prevent the re-establishment of infestations.”   

Funding for this year’s work is provided by the Australian Government through the Enhancing the values of the Gunbower Ramsar site project. ”A funding bid to continue work beyond June 2013 is currently being prepared,” concluded Mr Gibson.

For further information please contact: 

Communications Officer, North Central CMA
PO Box 18, Huntly VIC 3551
t: 03 5448 7124
e: info@nccma.vic.gov.au