Update December 2021
The early monitoring data from Lake Brearley is indicating the mixing device is performing as per design. This has resulted in a rapid equalisation of temperature in the shallow and deep water, as well as a spike in dissolved oxygen at depth (which for both Lake Brearley and Bungana has historically been almost completely deoxygenated). The monitoring unit is not immediately next to the mixer and is in fact approximately 60m from the mixing device. There has also been a distinct ‘lake wide’ change in colour of Lake Brearley (from yellowish to green) post commissioning of the mixing device indicating a progressive lake wide impact.
Despite the best efforts of all parties, the contractors have been unable to finalise the commissioning of the mechanical mixing device in Lake Bungana prior to Christmas. This is due to parts and labour being unavailable – a problem which is becoming common to many projects across the State and Australia-wide. This has now been scheduled to be completed by mid-January 2022.
Following the emergence of visible algal slicks and a deterioration in water quality in Lake Bungana in October/November 2021, City officers have undertaken a trial application of a bio remedial product called Aquaritin. This trial will determine its potential effectiveness in assisting to maintain water quality in the Maylands Lakes. Aquaritin is a concentrated liquid that contains micronutrients, including silica, which promote diatom growth. The premise of the product is the increase in density and richness of diatoms reduces nutrient availability (particularly nitrate) for nuisance algal growth. The product is not harmful to any other aquatic life. Initial field observations have highlighted a marked improvement in water clarity and a significant reduction in floating algal slicks in Lake Bungana post application of the product. Water quality sampling has been conducted throughout the trial by independent consulting firm Urbaqua to enable a comprehensive assessment of its effect.