Status of lakes and streams

Use of pesticides play an important role in ensuring good crop yields, but also carry a risk of toxic compounds entering the surrounding environment. Pesticides that are spread on agricultural land can be carried with rainwater down through the soil to the groundwater or via surface run-off, erosion and drainage water out to streams, rivers and lakes. On the way they are broken down, often to more harmless substances, but some reach the water recipient and there they can cause damage to plants and animals in aquatic ecosystems and pose a threat to drinking water quality.

Risk of damage has decreased

When pesticides began to be used on a greater scale during the 1950s, the products were initially applied without any great knowledge of the negative effects that can occur in the environment. Persistent compounds that accumulated in food chains were used, for example DDT. When knowledge increased about the risks of spreading pesticides, stricter rules were introduced on the compounds that could be used. Persistent and bioaccumulating compounds in particular had to be avoided. The amount of substances used has decreased in recent decades. The handling and application of these substances has also improved. All this has led to a decrease in the risk of unintentional damage to the environment, particularly the risk of a compound being able to have a long-term impact and to build up concentrations that are damaging to flora and fauna in the environment.