Environment Canterbury has met with the managers of the station at the centre of a cattle controversy involving Chief Justice Dame Sian Ellis and her husband, Hugh Fletcher.
The meeting follows the publication of photos of the cattle wading and drinking from Lake Taylor, right next to a Department of Conservation campground.
The cattle were owned by Dame Sian and Mr Fletcher.
Environment Canterbury is now investigating, and monitoring and compliance regional manager Marty Mortiaux said there was a lot to look at.
"We need to confirm ... that the stock are out of the water, and then we need to get an explanation from the property owner and/or the farm manager on why they were in there, and then we measure against what the actual adverse effect is."
Mr Mortiaux said Environment Canterbury was looking at the next step forward.
"We will determine what action we need to take. It could range from working with the farmer to ensure it doesn't happen again, or formalising that, or there could be some sort of enforcement action. We just don't know yet."
Edward Snowden, who owns a bach near Lake Taylor, said he had been complaining about cattle in the lake for 15 years.
Green Party co-leader James Shaw said the regional council seemed to be letting farmers get away with grazing stock along waterways.
"The most recent Environment Canterbury compliance report shows 95 complaints were made to the council about stock in waterways.
"In many districts it was the number-one complaint, yet only one polluter was fined. We want ECan to explain why this is.
"As it is, the $750 fine incurred for an infringement notice is far too low when you consider what is being done when cows enter a waterway.
"We're not just talking about pollution from cow effluent entering the water, it's about the banks being pugged and eroded too, which have consequences for water health."
Meanwhile, Labour believes there should be no special treatment when it comes to investigating the Lake Taylor case.
Party spokesman David Parker said Environment Canterbury should "treat this instance as any other. We're all equal before the law and in fact I'm sure that Dame Sian Elias and Hugh Fletcher would be the first to agree with that proposition."