Replenishing Perth’s Ramsar lakes – a partnership project
As a newly minted not-for-profit, one of Urbaqua‘s first partnership projects this year has been to scope options for the replenishment of one of the Perth’s prime Ramsar wetlands: Forrestdale Lake.
Ramsar wetlands were recognised by the UN in 1971 in the very UN-ishly named Convention on Wetlands of International Importance. The Convention aims to halt the worldwide loss of wetlands recognised as being of significant value not only for the country or the countries in which they are located, but for humanity as a whole.
The very WA State Government-ally named Strategic Environmental Assessment for the Perth and Peel Region (2015) (i.e. Perth & Peel’s Green Growth Plan) includes a commitment to investigate a stormwater supplementation program for Forrestdale Lake because of significant declines in water levels and bird activity, as well as lengthening dry periods.
Urbaqua stepped up to partner with State (DBCA, DWER, DLGSCI, and Conservation & Parks Commission) and Local Government (City of Armadale), the Water Corporation, and other community stakeholders (Perth NRM, Friends of Forrestdale) to identify and prioritise options to increase the water levels in the lake with the objective of restoring its Ramsar values.
A number of options to restore the lake were analysed, modelled and discussed with stakeholders over two sets of workshops run by Urbaqua in April and September 2017, which found that:
- understanding the wetting and drying cycle is critical (and that there is a very strong correlation between lake levels and local superficial groundwater levels);
- the Environmental Water Requirements (EWRs = peak water levels) should be formally changed to reflect 1980s conditions;
- rezoning of the local area is an opportunity to lock in an option to direct water to the lake via the district water management strategy;
- a Wetlands Coordinating Committee should be established to ensure delivery of recommended actions;
- based on modelling results, grading of select upstream drains and harvesting from nearby suburbs would restore the lake system and improve its resilience to future climate change.
In principle support for the recommended options has now been provided by government agencies (yay!). The next steps will be to:
- Refine water balance modelling of select nearby wetland systems to assess the potential impacts and mitigation options for water level decline following drain clearing;
- Develop revised EWRs for the lake that consider its current hydrological status and values, and that can be applied as a measure of the success and/or failure of replenishment; and
- Design a stormwater drainage system for the proposed new industrial area to the southeast of Forrestdale Lake that discharges into the lake with reduced on-site retention requirements.
Ongoing monitoring and evaluation is also recommended to ensure that Forrestdale Lake is on track to returning to its original Ramsar values. Learnings from this partnership projects will be applied to other sites on the Swan Coastal Plain in order to facilitate better environmental resilience to the changing climate. And almost as importantly we expect to see a return of more Red-capped Plovers, Long-toed Stints, and Curlew Sandpipers to our part of the world in the not too distant future!