Pollution
In addition to providing us with food, fibre, and fuel, agriculture and forestry also have vast impacts on water quality and water quantity. The main causes for concern with regards to the effects of land based activities on water quality arise from; sediment-borne contaminants from erosion and siltation; nutrient loads of chemical fertilisers, manure, waste water outflow, and septic tank leakage; pesticides; and salts from a range of human activities. The discussions during the 2010 World Water Week evolved around concrete measures that could be taken to reduce water pollution emanating from land based activities including steps to secure implementation and social acceptance. The need to apply a systems approach to the challenges of agricultural pollution was repeatedly highlighted during the Week. Reduction in pollution by non-agricultural polluters has been more rapid than for agriculture, especially with regard to nutrients. There has actually been an increase in point pollution from agriculture linked to the intensification, especially of livestock farming. However, there is also a greater publicawareness of the damage to aquatic ecosystems from agricultural practices and a growing concern related to groundwater, coastal zone and marine pollution, especially leaching of nutrients and pesticides. In addition, there is uncertainty over the extent and severity of emerging pollutants from agriculture, e.g. veterinary products. There is a clear link between the amount and intensity of agriculture and the overall pressure on water quality. In half of the OECD countries, nutrient and pesticide levels in surface and groundwater exceed national drinking water standards. It is important to identify opportunities and tools to reverse prevailing trends of water quality degradation and the role played by agriculture. The growing demand for agricultural products coupled with week institutional and policy frameworks, frequent market failures and an extra layer of uncertainty regarding changes in our climate, point towards increasing pollution from agriculture. At the same time, improving farming practices, increasing public awareness and pressure, and changing subsidy regimes may lead to a reversal of the trend of agricultural water pollution. The abatement of pollution from land based sources in general is a highly complex task demanding design and implementation of harmonised policies with a mix of solutions and costly monitoring due to the variation across space and time. The significant time lags also make it difficult to link policy actions to responses. There are often political, social and equity considerations that can influence policy choices and mixes. In many cases it is difficult to construct a robust management system that is adapted to the financial, technical and social capacities of local farmers, especially in developing countries. In general, increasing stakeholder involvement is a key factor in minimising land use based water pollution. There are several options that can be taken to reduce land based water pollution. Currently, there is no consensus on what measures are best suited to different circumstances, but enough is known to start piloting the approaches at significant scales. These pilot efforts have to be structured in a manner that allows for systematic monitoring, evaluation and if promising, up-scaling and replication.
