In principle, the federal government favours preventing pollution over treating it. To encourage pollution prevention and resource conservation, policies and programs have been developed in all parts of the country. Under these initiatives, information, technical assistance, and sometimes financial incentives are made available to farmers to encourage them to adopt conservation practices that protect soil, water, and air. Conservation practices that prevent, or at least reduce, the movement of agricultural substances into water are needed, especially in the areas at greatest risk.
Most pollution occurs in localized areas of watersheds.
In fact, many studies have shown that a small portion of a watershed may be responsible for most of the pollutant loadings of a watercourse. Targeting efforts to prevent pollution in these areas makes the best use of today's limited resources and encourages a streamlining of government policies and programs. It is a priority to identify these areas, a task that may be more complicated than first appears. Some agricultural situations that appear to pose a risk to water quality may, in fact, have little or no effect, while apparently nonproblematic situations may present serious risks of pollution and require corrective actions. Mathematical models that reproduce the physical and chemical behaviour of watersheds may be useful in identifying high risk areas and developing corrective plans.