Aging & filling of Lake Tuggeranong

["Jack and Andrea Holland" <>]

Philip's comments pertain particularly to the main lake, which took a while to fill up.  Besides being bigger there was also an unexpected drain through a former sewage works site.  This maintained water levels at a premium for crakes etc for quite a while.   Whether they were forced to the edges or flew in from somewhere else is unclear, but they disappeared overnight with the first major rain (yes we used to get that!) after the hole was located and plugged and the lake filled up quickly.

 

A number of the smaller ponds filled up very quickly and a feature was the large number of ducks, coot etc on them as soon as this happened.  I believe this may have been the result of the higher nutrient levels on flooding of the previous grassland, which stabilised/dropped relatively rapidly, though I have no proof of this.

 

I agree with Martin that Musk Duck were common on LBG during the 1970s and early 80s.  Why they are no longer present is unclear, but I doubt it is nutrient related.  Some people believe it's related to the presence of carp.  Certainly they are present on bodies of water north of Canberra such as Pejar Dam and the lake we visited at Marulan in March, again both well established and I assume containing carp.  The Great Crested Grebe is similarly more common at theses two lakes, the report of 8 at Lake Ginninderra earlier today is the highest number I can recall and well worth having a look at.  One very good diagnostic feature is to look for their very white chests if they are loafing with their heads tucked away (usually in pairs).

 

Jack Holland