A review of the policies and implementation of practices to decrease water quality impairment by phosphorus in NZ, the UK, and the US

We outline policy in New Zealand, the UK, and the US who have imposed limits for P. We contrast the strategies used and discuss their likelihood of being able to decrease P losses and improve water quality. A poor understanding of catchment processes and critical source areas of P loss has resulted in some areas where regulation has had minimal effect on P discharges. Furthermore, we give several examples where social and economic challenges are of equal if not greater relevance to P discharges (e.g. subsidies). Other policy instruments (e.g. trading schemes) may be needed at larger scales, but should be flexible and encourage innovation. There is increasing recognition among all 3 countries that while targeting good management practices can substantially decrease P losses from existing land use, to achieve ‘good’ water quality in catchment, policy may have to consider land use change.