The decision has significant implications for ACT Chief Minister Katy Gallagher, who lives at the northern end of Canberra's inner north and looks quite likely to have her suburb swallowed up in a new Gungahlin-based electorate. The boundary could well cut across the inner north suburbs, leaving others in a city-based electorate.

The ACT Electoral Commission issued its population projections for 2016 on Wednesday, along with an interactive map where you can experiment with drawing your own boundaries - and if you like, send your map in as a submission.

The commission is creating five electorates out of the current three, each of which will have about 56,000 voters. Each electorate will elect five politicians to the new 25-strong Assembly.

The commission's mapping tool immediately makes it clear just how far Gungahlin falls short of the required numbers. Even with its fast growth, it is expected to have just 40,500 voters in 2016, leaving it well short. It can extend into Belconnen, but if it goes in that direction it needs to take in not only Kaleen and Giralang, but also potentially the solidly Belconnen suburbs of McKellar, Evatt and Spence to make up the numbers. Alternatively it could reach through Kaleen to Bruce and Aranda.

A more simple solution to the Gungahlin numbers problem is for it to reach down into Lyneham, Watson and Downer. Even so, it would need to take in Kaleen and Giralangunless it was to reach still further into the inner north, swallowing the likes of Hackett and Dickson, which is Deputy Chief Minister Andrew Barr's suburb.

There is no requirement for politicians to live in their electorates, but that has been their preference and practice. The Liberals' Alistair Coe, who lives in Giralang, is the only other sitting member likely to find himself representing Gungahlin.

The Electoral Commission's redistribution committee, which has called for public submissions on the boundaries until December 4, must keep voter numbers in each electorate within plus or minus 5 per cent of the quota of 56,000 (based on projected enrolments in 2016). It considers communities of interest and geographic boundaries when it draws up the electorates.

The university suburbs of Bruce, Aranda and Cook are also likely to be looked at in the redistribution, as the commission decides whether they should sit with Belconnen or with the inner north, where they arguably have a stronger community of interest.

In the south, the jigsaw puzzle looks a little easier to put together. Tuggeranong looks like it will have to lose Kambah to the new Woden-Weston Creek electorate, along with Farrer, Torrens, Pearce and Chifley, but otherwise is a fairly discreet electorate of about the right size.

Woden and Weston Creek, where a number of the sitting members live, including Liberal Leader Jeremy Hanson and Capital Metro Minister Simon Corbell, doesn't look like it will need to reach into the inner south beyond Hughes, Curtin and Garran to make up its numbers.

The Electoral Commission's map appears to rule out a scenario mooted by some of using the lake as an electorate boundary, separating the inner south suburbs from the inner north, given the arguably quite different communities of interest. But it is difficult to see how that could work without unwieldy incursions of Gungahlin into Belconnen, and Belconnen in Weston Creek.

The population projections, from the Australian Bureau of Statistics, predict 279,845 voters at the next election, up 4 per cent on August 2014. Most of the big growth is in Gungahlin and new suburbs, with numbers dropping most markedly in Yarralumla (down 149 voters, or 6 per cent) and Red Hill (down 85 voters, or 3.6 per cent).