Farmers are being asked to watch where their irrigation water goes - and keep it off the roads.
Environment Canterbury principal resource management adviser Richard Purdon said several complaints have already been received, so irrigators need to adjust their aim.
''Irrigation on to roads, particularly gravel roads, is not only a waste of water but also has the potential to create safety issues for motorists.
''It is the surprise element and the force of the water that could easily startle a motorist. It is especially dangerous for those on motorcycles.
''Our staff have been receiving an increasing number of calls, especially in our Ashburton office, and our locally-based water zone officers will be responding to these on a case-by-case basis,'' Mr Purdon said.