Publication Date

2-2021

Publisher

State of Western Australia (Department of Primary Industries and Regional Development)

City

Perth

Abstract

In 2008 the Ord Irrigation Expansion Project was approved by the Western Australian Government to develop irrigated agriculture on the Weaber Plain and surrounding areas. The expansion, referred to as greater Ord Stage 2 included land along the lower Ord (Packsaddle, West Bank, Carlton Station and Mantinea), the Cockatoo Sands, as well as the Weaber, Keep River and Knox Creek Plains as suitable for development. Construction of the M2 supply channel connecting the Ord River Irrigation Area and Weaber Plain, and the final period of irrigation design, environmental management and related approval processes, commenced in 2010. Approximately 7,400 ha were granted to develop the Weaber Plain, now referred to as Goomig farmlands, requiring 120 GL irrigation supply from Lake Argyle. The farm design in the development is based on the use of an irrigation tail-water management system, with irrigation runoff from irrigated land to be reused on farms (GHD 2010).

Wetland Research & Management (WRM) were commissioned by LandCorp to survey macroinvertebrate and fish assemblages to establish baseline ecological condition, as well as occurrence of listed species, including targeted sampling for sawfish and Glyphis sharks. WRM were then commissioned to undertake three pre-development baseline surveys of the Keep River, with surveys completed in 2011, 2012 and 2013. Part of baseline data collection was to also provide data on sediment and water quality that were used to develop interim local surface water trigger values for assessing effects of any discharge to the Keep River. WRM applied standardised methodology across all three baseline surveys (2011, 2012 & 2013) and thereby developed a robust baseline to allow detection of any future impacts from the ORIA Stage 2.

Project Conditions require three-post-development surveys to assess changes to listed species and ecosystem health as a result of the development. WRM were commissioned to conduct the first of these post-development surveys, with the same four main river pools, three estuary and five reference sites revisited in September 2020, with sampling conducted using identical methods to baseline sampling.

Number of Pages

99

Keywords

Ord River, Keep River, ORIA, irrigated agriculture, environmental compliance reporting, Western Australia, Environment Protection and Biodiversity Conservation Act 1999, aquatic fauna, sawfish

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