The Welsh government will introduce a nitrate vulnerable zone (NVZ) designation across the whole of Wales in a move that has angered farming groups.
It comes as agricultural pollution incidents 'remain very high' in Wales, according to the Welsh government, averaging over three per week in the last three years.
It said some of these had led to the contamination of drinking water sources and the destruction of plant and aquatic life in parts of waterways.
NVZs are areas within Wales that contain surface water or groundwater susceptible to nitrate pollution from agricultural activities.
They are designed to improve water quality in rivers and lakes, but it would mean tougher restrictions on fertiliser and manure spreading.
But numerous farming groups in the country believe the all-Wales proposal would not be effective in delivering water quality improvements.
However, the Welsh government announced on Wednesday (27 January) that the industry had the past four years to address the issue.
Support worth £1.5 million will aim to help farmers improve water quality and £11.5m of capital funding will help improve nutrient management infrastructure.
The Minister for Rural Affairs, Lesley Griffiths said: "Agricultural pollution has affected water bodies across Wales for far too long and I am determined to act to protect the Welsh countryside, while supporting our farmers that want to do the right thing.
"We continue to face a rate of more than three agricultural pollution incidents per week, and against such a backdrop, we are bound to do all we can protect the public and the environment.
"This also provides an opportunity for farmers to uphold exceptional standards that in turn will bolster the image of Wales’ agricultural industry."
Industry groups have reacted with concern with the announcement, particularly given the gravity of the current Covid-19 pandemic.
NFU Cymru said an all-Wales NVZ would be 'indiscriminate and punitive' as it would 'affect every farmer, every sector and every area of Wales'.
The union said the designation would bring 'draconian record keeping, complex restrictions on the day-to-day running of their businesses and, for many, exorbitant costs.'
President John Davies said: “We can only conclude that, in taking this decision, government continues to have absolutely no comprehension of the impacts of these regulations.
"The levels of investment committed to help farmers adapt to these new conditions is, frankly, woefully inadequate when you consider the capital investment support given to farmers in other countries where similar approaches to water quality have been adopted.
"We are extremely disappointed that Welsh government appears to remain oblivious to the significant limitations and damaging impacts of the NVZ approach."
Initial 'good practice requirements' for the NVZ roll-out will be introduced from 1 April 2021, the Welsh government confirmed.