Imported aquatic plants causing problems on New Zealand rivers and waterways.
About 50 varieties of imported aquatic plants are making their way into rivers and waterways causing problems for electricity companies.
The National Institute of Water and Atmospheric Research (NIWA) has been trialling native plants to replace imported varieties that go into home aquariums and ponds.
It says they are slowly making their way into rivers when ponds spill over or when aquariums are tipped out.
A wetland ecologist with NIWA, Kerry Bodman, says its working to manage some of the worst areas where the imported varieties end up.
Ms Bodman says this includes power generation rivers where the plants block the flow of water, so the electricity companies pay get the plants sprayed or use equipment to filter them out.
