A report to the Commonwealth Environmental Water Office
About the document
Narran Lakes (Dharriwaa), a large terminal wetland at the end of the Narran River in the Lower Balonne floodplain is one of Australia's more important breeding sites for colonial waterbirds and is listed under the Ramsar Convention. Up to 200,000 ibis have been recorded breeding at the site but significant breeding events last occurred in 2011-12. Dharriwaa experienced extreme dry and hot conditions from 2017 to 2020 and little significant inflows since 2012-13 until early 2020. While wetter conditions returned from 2020 onwards, waterbirds did not breed at the site until early 2022. The Commonwealth delivered water for the environment through its unregulated Queensland entitlements in 2020, 2021 and 2022. Extra water was also delivered through an event-based mechanism grant to landholders on the Narran River in 2020, which resulted in an extra 9 GL reaching the Lakes and helping waterbird habitat improve in condition.
Flow targets for large-scale waterbird breeding at Narran Lakes were met at the end of 2021 and waterbirds were observed starting to nest in early 2022. The University of New South Wales in collaboration with NSW Department of Planning and Environment – Environment and Heritage Group and NSW National Parks and Wildlife completed detailed monitoring of waterbird breeding at Dharriwaa from January to April 2022, including on ground surveys, use of drones and remote information from aerial flights and satellite imagery. Key findings from the project include:
- Just over 10,000 nests of straw-necked ibis were observed in the Narran Lakes Nature Reserve, with most in a northern colony and smaller number in the southern part of the lakes. Other species nesting included royal and yellow-billed spoonbills and egrets. These locations were similar to previous breeding events.
- However, the 2021-22 breeding event was much more dispersed compared to previous years, with birds nesting over a wide area and with number of nests per clump being particularly low. This may be due to relatively poor quality of the lignum in some areas for nesting. The relatively low number of nests compared to larger breeding events elsewhere in the Basin this season may also be due to a “dilution effect” with lots of opportunities to breed elsewhere and a limited population size.
- The report makes recommendations around e-water delivery to promote waterbird breeding and supporting habitat for nesting, roosting and foraging. It also makes recommendations on monitoring needs and knowledge gaps.
The views and opinions expressed in this report do not necessarily represent the views of the CEWO. This publication does not indicate commitment by Commonwealth government to a particular course of action nor has the CEWO made any decision on options identified in this study.
The CEWO reserves the right to, in the future, further consider any of the options proposed in the report or options in addition to those identified.
The content of this report does not constitute advice to any third party. Although due care and skill has been applied in the preparation and compilation of the information and data in this publication, no reliance may be placed on it by any other party. No representation expressed or implied is made as to the currency, accuracy, reliability, completeness or fitness for purpose of the information contained in this publication. Readers should rely on their own inquiries to independently confirm any information and comment on which they may intend to act.
The Commonwealth of Australia, its officers, employees, agents and the other parties involved in creating this report disclaim, to the maximum extent permitted by law, responsibility to any other party for any liability, including liability for negligence, loss howsoever caused, damage, injury, expense or cost incurred by any person as a result of accessing, using or relying upon any of the information or data in the report.