Lake Macdonald - Environment
Lake Macdonald is the main water supply for the town areas of Noosa Shire and as such is very important for all of the people who are living in townships in Noosa Shire as it is the source of their fresh drinking and bathing water. It also provides water to all of the shops, factories and community facilities in those township areas, but in addition to this Lake Macdonald is a large habitat which provides a home for a wide variety of native plants and animals. Being a very large fresh water lake, Lake Macdonald provides a home for a wide diversity of fish, birds, frogs, insects, reptiles and some mammals.
The Lake Macdonald Fish Hatchery which is located on the northern banks of Lake Macdonald has been developed over the years to produce baby Mary River Cod which are released into the waters of Lake Macdonald and other waterways of the Mary River System and across South East Queensland. The Mary River Cod is listed as an endangered species by both the Commonwealth and State
Governments. The endangered species status of this fish is also recognised by the International Union of the Conservation of Nature. Lake Macdonald provides a good habitat for Mary River Cod as it is a large water body with a variety of different depths and habitats. There are some large submerged logs within the lake where Mary River Cod can lay their eggs and protect them from other predatory fish. Lake Macdonald is also connected to other waterways such as the headwaters of the Six Mile Creek where small cod can move to establish their own territories. In periods of high flow some cod, no doubt, also flow over the spillway and help to establish cod populations in the Six Mile Creek downstream of Lake Macdonald.
Lake Macdonald is also an important place for birds and a trip to Lake Macdonald bird hide is a great opportunity for bird observers to sit and watch the wide variety of bird life that come to use this lake. The birds that use Lake Macdonald include wading birds which wade about in the shallows hunting for small fish, insect larvae and also may eat various plants. These types of birds would include Herons, Jabiroo and Egrets. It is also home to diving birds such as Cormorants which dive down underwater in search of small fish, and plant eating diving birds such as Swans who thrust their heads down under the water in search of succulent plants to eat. There are also the Raptors such as the Whistling Kite, Brahmany Kite, White Breasted Sea Eagle and Osprey which fish on the lake
Within Lake Macdonald there are also a wide variety of frogs, turtles, snakes, and within the margins around the lake, there are mammals which include platypus, water rats, antichinus, phascogailes, wallabies, echidnas, quolls, gliders and possums. All of the land around the lake’s edge is in the ownership of Noosa Council and wherever possible land has been rehabilitated with native vegetation to help filter nutrients from farmlands out of waters before they enter the lake and also to provide habitat for the variety of plants and animals that make the lake and surrounds their home.
The major problem for the ecosystems of large lakes like Lake Macdonald comes from nutrients and sediments flowing into the lake off surrounding land as a result of erosion from farmlands and from other land management practices. These nutrients and sediments cause infill of the lake reducing its total water carrying capacity but also promote the growth of algae and aquatic weeds and in Lake Macdonald. Two
such weeds have become very bad pests. One is called Cabomba and Council has a special harvesting program to try and harvest Cabomba out of the lake to reduce its impact on the lake’s environment and the water quality. The other is Hygrophyla which is a plant that grows around the lake’s margin between the water level and the
banks around the lake. Both of these weeds are very bad pests in Lake Macdonald and their presence in the lake is a major concern to the Council. Both weeds were introduced illegally and will quite likely create major problems for ongoing management of the lake for some time to come.
Even though Lake Macdonald is an artificially constructed waterway, its still provides significant environmental values to the local area and plays a role in maintaining the diversity of plants and animals within the South East Queensland region. It also provides a very important corridor for movement of animals between large bushland areas within Noosa Shire and a major stopover point for bird species which migrate between southern and northern Australia.