The Government has also embarked on using grass carp in aquatic weed eradication projects, such as Lakes Tutira, Opouahi and Waikopiro for Hydrilla and in Lakes Swan, Heather, Kereta for Common Hornwort (Ceratophyllum).
In the mid 1980s, isolated occurrences of Rigid Hornwort had established in the lake, and, by the mid 1990s, abundant quantities of other aquatic plants such as Ivy Duckweed and the liverwort Riccia Fluitans, were reported along open edges of the lake.