Diffuse Pollution, Degraded Waters

Emerging Policy Solutions

image of Diffuse Pollution, Degraded Waters

After decades of regulation and investment to reduce point source water pollution, OECD countries still face water quality challenges (e.g. eutrophication) from diffuse agricultural and urban sources of pollution, that is disperse pollution from surface runoff, soil filtration and atmospheric deposition. The relative lack of progress reflects the complexities of controlling multiple pollutants from multiple sources, their high spatial and temporal variability, associated transactions costs, and limited political acceptability of regulatory measures. This report outlines the water quality challenges facing OECD countries today, presents a range of policy instruments and innovative case studies of diffuse pollution control, and concludes with an integrated policy framework to tackle diffuse water pollution. An optimal approach will likely entail a mix of policy interventions reflecting the basic OECD principles of water quality management – pollution prevention, treatment at source, the polluter pays and beneficiary pays principles, equity, and policy coherence.



Executive summary

Decades of regulation and large investments to reduce point source water pollution have brought substantial gains for the economy, human health, environment and social values. But water quality challenges endure in OECD countries as a result of under-regulated diffuse sources of pollution. Eutrophication, a form of water pollution due mainly to agricultural runoff of excess nutrients, is the most prevalent challenge globally.


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