Irrigators have 10 working days to comply with Environment Canterbury rules on installing water meters or risk enforcement action.
There have been more than 350 serious breaches by irrigators of water restrictions, and ECan previously warned every irrigator would need a water meter by July.
Now it says it has contacted about 500 water consent holders who haven't yet installed a water meter for takes over 10 litres per second.
All have either agreed on a plan to install a meter, or are aware they have 10 working days to provide evidence that action is being taken, ECan spokeswoman Nadeine Dommisse says.
"What we have found that once contacted, many people took action immediately or provided evidence they had a plan in place to install the necessary equipment and systems."
ECan came under fire from Forest & Bird last month for not taking a hard line what it called the "massive scale of water theft in Canterbury".