"Farmers are intensifying. It was 60 cows per herd, it's now 100. The average age of farmers is 58 years, but for dairying it's lower. We're finding young farmers are a problem, too, because they're under such pressure to expand. Farmers are not buying into it. They do it out of fear of inspection. They don't see the value."
He points to the requirement for farmers to calculate how much nitrogen and phosphorous can be safely spread on the land, which adds an "extra layer" of difficulty.
Just over 20pc of all land surveyed is believed to be in optimal condition. Mr Nolan suggests that most land doesn't have the right level of phosphorous, nitrogen and lime.
"Part of that is fear of regulation, costs, and in part due to a lack of education. It will lead to problems down the road. You can't keep increasing output if you're running down the soil.
"Farmers are delighted when I leave the yard (after inspections). The reason is they don't trust us. There's a fear attached when the Department of Agriculture comes. That's not the way it should be."
Some 400,000 jobs are in water-intensive industries including food production and agriculture, meaning the links between farming and clean waters are critically important.
Major challenges exist.
The EPA says that in 1996, 4pc of our waters, including rivers and lakes, were classified as 'pristine'.
That has now dropped to 0.7pc. On the other hand, 20 years ago some 77km of river channel were classed as 'seriously polluted', which has fallen to 6km. But there are now an additional one million cattle on the land, which is increasing pressures.
The numbers will grow -since the removal of milk quotas in 2015, the number of dairy cows has increased by 300,000. It is projected to rise by 6pc this year, and 6pc in 2018.
That puts further pressure on already stressed water bodies, with the EPA saying that of 4,000 river and lake water bodies, 1,360 - or 34pc - are at risk, often from multiple sources.
Senior catchment scientist at the EPA Jenny Deakin points out that half of all at-risk water bodies face multiple-pressures - agriculture, urban wastewater treatment plants, forestry and extractive industries including mining and peat production. "The greatest number of water bodies are impacted by agriculture, but there's no surprise there because agriculture is by far the biggest land use," she said.
"It's particularly challenging due to the number of water bodies, the diverse number of landholders involved, the lack of resources on the farm to take actions and the multiple agencies and players. A one-size-fits-all solution won't work."
Many suggest now is the time for debate and to put in place measures to help farmers become greener and reduce the impact of their activities on water courses and the wider environment.
Chair of the National Water Forum Tom Collins says things have changed a lot in the last two decades.
"We do need a debate," he told the conference. "I think farming is at a tipping point around the environment. It has learned that clean water is an essential ingredient, and that is a shared preoccupation with the farming community.
"Farming is at a perfect tipping point where it is realising that it is very much in its interest to get behind this project. That is an enormous development from where we were 20 years ago."
Work is happening on the ground. Under the National Dairy Sustainability Initiative, 180 farms will be chosen by early autumn as test sites for a range of environmental works. The Local Authority Water and Communities Office (LAWCO) is working with farmers, angling groups, local development companies and others to highlight concerns and set out possible solutions.
Thomas Ryan, executive with the IFA's environment and rural affairs committee, asks that people "walk in our shoes" and look at environmental work on the ground.
"There's so much happening, and more can be achieved because we can't afford to get it wrong. The journey we're on is a journey of collaboration."
Dr Donal Daly from the EPA agrees, saying the future is collaboration and not diktats.
"Farmers don't like being told what to do and we have to take that into account. Farmers are custodians of the rural environment, and we have to see how we can assist them.
"Most farmers' contacts with the environment are in the form of inspections, and many fear inspections. We need to move away from that."