Frequently Asked Questions
What is the problem with Dowse Lagoon and how did it get like this?
There are a number of problems which are affecting the health of the Lagoon. The main problems, such as the Midge infestations and algal blooms, are associated with the poor water quality.
One of the reasons why the water quality is poor is because the Lagoon is an isolated water body which receives its water only from direct rainfall and some runoff from the surrounding streets. The relatively small amount of water that enters the Lagoon when it rains is rarely enough to flush it out and refresh the Lagoon. Over time concentrations of pollutants in the water build up to unsustainable levels. The problem has been worse more recently because of the drought conditions.
In addition to this the past two decades have seen a number of aquatic weed outbreaks which have covered the Lagoon. After treatment the weeds generally sank to the bottom of the Lagoon where they now form a very thick layer of organic material (rotting vegetation) which contributes excessive amounts of nutrients to the water.
The shape and depth of the Lagoon is also contributing to the problem. On a typical sunny day the Lagoon acts like a big frying pan, heating the water to temperatures which encourages algal blooms and makes it difficult for many native species to survive. Even when the Lagoon has a substantial amount of water in it the average depth is generally less than one metre. (The average depth at the moment would probably be less than 300mm) There is also very little if any shade to help cool the Lagoon’s water.
It is the combination of all these problems that have over time reduced the water quality.
There is plenty of wildlife in and around the Lagoon so I don’t see why there is a problem.
Yes, some species will still survive in the conditions which have been described above. However these conditions are not conducive to a healthy habitat with a diverse range of species. In conditions such as Dowse Lagoon there will tend to be a couple of species that will dominate simply because they are able to adapt more readily and are less susceptible to fluctuations in temperature, dissolved oxygen and algal toxins. A healthier water body will attract a much larger diversity of species.
If we leave it alone will it fix itself?
No, the problem will not go away. It may improve if we get some regular long-term rainfall however all the ingredients will still be present for the system to continue to deteriorate. The rehabilitation plan will be aimed at a long-term solution to the problems and not a quick fix.
What is being done to fix it?
The Brisbane City Council has committed funds to investigating the problems and developing a rehabilitation plan. Some preliminary technical investigations have been completed and a community reference group (CRG) has been formed to assist with developing a concept plan for the Lagoon’s rehabilitation.
I heard that the Council wants to fill in the Lagoon, is this true?
No, this is not accurate. The investigations undertaken to date indicate that water quality and water temperature are closely related. The preliminary investigations recommend amongst other things to consider deepening areas of the lagoon to reduce the water temperature. Deeper water is cooler healthier water and provides for greater diversity of species. The material on the bed of the lagoon is unsuitable for removal and hence any exercise to deepen areas will result in excess material needing to be placed somewhere within the site of the Lagoon. The CRG will be considering these issues in the development of the concept plan.
When will something be done?
The process to develop a rehabilitation concept plan has already begun and will hopefully be completed by the middle of this year (2003). This will be followed by a public display period where community members will have the opportunity to comment on the proposed plan before it is finalised. Following this, a detailed design will be made based upon the concept plan and all necessary licences and permits will be sought to undertake the proposed works. Without knowing what is to be proposed as the rehabilitation concept plan it is not possible to forecast at this stage when any physical works may start on site. The CRG will be providing regular feedback on the process via a weekly column in the Bayside Star.
How can you help?
To begin our development of the rehabilitation concept plan we are collating a list of issues and features of the Lagoon which will be considered as a part of any proposed solution. We would appreciate your thoughts and ideas on the following items:
- What existing problems are you aware of?
- What are some features you would like preserved or enhanced?
- What are some new features you would like to see added?
- Do you have any historical information about the Lagoon or pictures that you would be willing to share with the CRG?
Thank you for your interest in the rehabilitation of Dowse Lagoon. If you would like more information or have any ideas or comments, please contact us by e-mail on dowselagoon@sandgate.org.au
