Nitrogen levels in water resources in the Waikato region are increasing, mainly as a result of non-point source pollution from agricultural activities. Non-point pollution management is a complex issue requiring sufficient information and appropriate institutions. This paper considers the environmental policy literature and analyse how institutions, contract design, and monitoring and transaction costs in the presence of farm heterogeneity encourage optimal abatement. The analysis identifies the key institutional issues to be addressed in the design of appropriate policy measures to address water quality in Waikato river sub-catchment.