Miljødirektoratet (The Norwegian Environment Agency) coordinates the national watercourse liming which is carried out in Norway in order to counteract the effect of acid rain. As part of this work, a control scheme was set up in 1996 for watercourse lime, the objective of which is to control that the lime delivered is of the agreed and approved quality. The control scheme involved the analysis of lime samples from the lime works/lime stock and spot checks from lime delivered in the field, and analysis statistics and turnover statistics are prepared and published for lime delivered to watercourse liming (annual statistics bulletin). The Norwegian Environment Agency has an agreement with a laboratory for the analysis and preparation of statistics. The control scheme also includes follow-up and control of the lime supplier's internal control and declaration of lime products, and control with sodium silicate products used in some waterways as an alternative to lime.