The aim of this requirement is to protect surface water from pollution by nitrate, phosphorus, plant protection products and faecal pathogens by creating buffer strips.
Amcan y gofyniad hwn yw diogelu dŵr wyneb rhag cael ei lygru gan nitradau, ffosfforws, cynhyrchion diogelu planhigion a charthion pathogenig drwy greu lleiniau clustogi.