Project Details

WSUD Category: Wetland/lake algae management

Development Type: Public Open Space
Function/Driver: Water quality
Government Area: City of Mandurah
Year Completed: 2019

 

Type of wetland

Constructed – Urbanised

Description of the 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.
  • There are four storm water inlets connected to the waterbody, which provide annual stormwater from residential areas and parks runoff.
  • The waterbody has no aerators or active mixing.
  • Ongoing water quality monitoring reports that the water is consistently high in nutrients.

Treatment trialed

  • Name of treatment: Phoslock
  • Quantity used: 2,367 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. “Lyndhurst Place 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 91% after two weeks and by 75 % after three months. Also, Phoslock treatment has helped to drop the EC or TDS levels in water and show a 50% reduction in Biochemical Oxygen Demand (BOD) levels after 3 months. Reduction in BOD could be helpul in maintaining DO levels in water, which is good for this lake as there is no active aeration system installed.
  • 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

Email: [email protected] and [email protected]

 

Submit a Project