Alkimos Seawater Desalination Plant

Project
Proponent
Proposal description

The Western Australian Water Corporation is proposing to construct the Alkimos Seawater Desalination Plant (ASDP) as part of Perth’s Integrated Water Supply Scheme which aims to provide additional sources of drinking water to supplement the existing metropolitan water supply.

The ASDP Proposal will be located within the Alkimos Water Precinct (Lot 1050 Marmion Avenue), approximately 40 km north of the Perth, within the northwest corridor, north of Quinns Rock beach and south of Yanchep beach.

ASDP will be developed in four stages (each with a capacity to supply 25 GL) with the timing of each stage based on actual growth in water demand, potential groundwater allocation reduction, actual streamflow conditions and timing of other source option development (e.g. construction of the proposed PSDP2 at Kwinana).

The Proposal requires the installation of two seawater intakes and two seawater return outlets (approximately 4 km offshore) to enable the discharge of return seawater (brine) to the marine environment.

Assessment Number
2210
Region
Referred under EP Act
s38
Industry sector
Last updated
Current Status
Ministerial Statement published
1. Referral
Referral documentation
2. Decision on whether to assess this proposal
3. Assessment
Scoping
Environmental scoping document
Approved
Environmental Review
Environmental Review documentation
Date Published (Environmental Review documentation)
Proponent response to submissions
Date published (Proponent response to submissions)
Minor or preliminary work under s. 41A(3)
Date of approval s. 41A(3)
Change to proposal during assessment under s. 43A
4. EPA Report on assessment
EPA Report Number
1739
Date published
Appeals close
5. Decision on proposal and implementation of proposal
Ministerial Statement
Date of approval
Ministerial Statement
Post-assessment changes
s. 45C amendments

Attachment 1 to Statement 1207 - Increase the proposal development envelope from 141.6 hectares (ha) to 142.73 ha. Decrease the marine development envelope from 11.45 ha to 11.42 ha. Increase the terrestrial development envelope from 130.15 ha to 131.31 ha. Proponent updates to the ‘Proposal Content Document’, as amended by the change to proposal approved under s.43A on 7 March 2023 to reflect the amendment approved under s.45C on 17 April 2024.Changes to conditions to reflect the change in the authorised extent of impacts. Change to conditions approved under s45C on 17 April 2024

Attachment 2 to Statement 1207 -  Increase the proposal development envelope from 142.73 hectares (ha) to 195.74 ha. Increase the terrestrial development envelope from 131.31 ha to 184.32 ha. Decrease the clearing of native vegetation from 51.20 ha to no more than 50.95 ha. Changes to conditions to reflect the change in the authorised extent of impacts to flora and vegetation, terrestrial fauna, and landform environmental values. Remove condition B1-2 and Figure 3 relating to the requirement for additional survey for Banksia attenuata woodlands over species rich dense shrublands (floristic community type 20a) threatened ecological community. Change to conditions approved under s45C on 21 January 2025.

Attachment 3 to Statement 1207 -  Increase the marine development envelope from 11.42 hectares (ha) to 77.79 ha.
• Change the outlet design from two 7 metre (m) diameter rosette diffusers to a single linear diffuser
• Change the definition of the Low Ecological Protection Area (LEPA) to accommodate the proposed change to the diffuser
• Change condition A1 to reduce the maximum salinity limit from 75,200 milligram per litre (mg/L) to 68,000 mg/L
• Decrease the maximum irreversible loss of benthic communities and habitats from 0.13 ha to 0.10 ha
• Increase the maximum disturbance to benthic communities and habitats from 8.39 ha to 8.68 ha
• Change the proposal description.. Change to conditions approved under s45C on 13 March 2025.

Date of approval s. 45C
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