WSUD Category: Wetland/lake algae management
|Development Type:||Public Open Space|
|Government Area:||City of Mandurah|
Type of wetland
Constructed – Urbanised
Wetland management issue
- The waterbody has a natural groundwater connection due to the low groundwater table. The lake is not supplied with any further groundwater via a bore system.
- The waterbody has a disconnected drainage network with stormwater only entering the lake on big rainfall events via one bubble-up storm water outlet.
- The waterbody receives stormwater from residential areas and parks runoff.
- The waterbody is supplied with oxygen and mixing via five aerator diffusers run by solar power.
- The water quality experiences ongoing sources of nutrients and is continuously eutrophic with high levels of phosphorus.
- Name of treatment: Phoslock
- Quantity used: 2,000 kg
- Method of application: Mobile shore-based application equipment.
- Is there any known scientific research supporting its effectiveness? Yes. Proposal for Phoslock treatment of Lyndhurst Place Lake Mandurah, Report, Phoslock Environmental Technologies.
Date(s) of treatment
27/05/2019 one-off application
Outcome of treatment
- Visual observations: Water column seems clearer.
- Have water parameters specific to the treatment claims been measured before and after application? Yes. “Cox Bay North Lake Quarterly Health Check Report, EcoAdvise, August 2019″ (available upon request).
- Water testing was carried out on the 12/06/2019 after the first major winter rainfall event. Further regular quarterly testing was carried out on the 8/08/2019.
- Phoslock treatment reduced the TP concentration in the water considerably, by 73% after two weeks and by 94% after three months. Also, Phoslock treatment has helped to drop the EC or TDS levels in water and showed a 71% reduction in Biochemical Oxygen Demand (BOD) levels after 3 months, which would help to maintain the dissolved oxygen levels in the water.
- Although the TP level dropped post Phoslock treatment, TN and TP levels remained high enough for the lake to be considered eutrophic.
Contact Officer: Tanith McCaw and Dale Robinson