Farmers in England will have to be aware of extensions to nitrate vulnerable zones (NVZs), the Department for Food, Environment and Rural Affairs (Defra) has said.
New regulations from Defra have called for an extension in these areas from 55 per cent to around 70 per cent.
As a result, farmers in these areas will have to take action to reduce the amount of nitrates from manures and fertilisers that ruin
water quality in nearby rivers.
The new regulations will also limit the times of year that fertilisers can be used on land.
Phil Woolas, environment minister, said: "Tackling pollution from agriculture is central to boosting the quality of our water environment."
He added that, if unchecked, farming activity can have an adverse effect on lakes, rivers, coastal waters and estuaries.
Earlier this week, Defra claimed farms may be able to make use of anaerobic digestion to convert organic matter into biogas and protect the water environment.