The Welsh Conservatives have called on the devolved government to reverse the introduction of an all-Wales nitrate vulnerable zone (NVZ).
Last month, the Welsh government said it would introduce the controversial measure across the whole of Wales in a move that had angered farming groups.
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.
The Welsh government's motion to introduce the new rules will be brought before the Senedd in early March.
But numerous farming groups believe the plan would not be effective in delivering water quality improvements, and would instead increase burdensome regulation and costs.
Welsh Conservative rural affairs spokesperson, Janet Finch-Saunders, said the plan was a 'real kick in the teeth' for farmers.
“On numerous occasions Labour promised farmers they wouldn’t introduce these regulations while we were still dealing with the coronavirus crisis.
“They’ve broken that promise and shown farmers and the Welsh public you can’t trust Labour when it comes to protecting livelihoods and the food security of Wales and our UK.
“Welsh Conservatives would scrap these plans after May’s Senedd election but we hope ministers listen to our calls today and reverse this decision immediately."
However, the Welsh government's announcement on 27 January highlighted that the industry had the past four years to address the issue.
Support worth £1.5 million will be issued to help farmers improve water quality and £11.5m of capital funding to improve nutrient management infrastructure.
The Minister for Rural Affairs, Lesley Griffiths said last month: "Agricultural pollution has affected water bodies across Wales for far too long.
"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."
Initial 'good practice requirements' for the NVZ roll-out will be introduced from 1 April 2021.
