Plant has established as several places along a shoreline, from where these photos were taken, to opposite Yarralumla House. Noted in water, on moist soils amongst terrestrial plants, and out off-shore in amongst Typha.
Hi @JaneR and @MichaelMulvaney thank you for tagging me in this post, we are aware of the presence of alligator weed in this area, it was treated on the 22/1/23. Please see the attached link https://actgov.maps.arcgis.com/apps/dashboards/5449adb632884d68aeb585e3e73dde99