This impact study has been prepared to present the economical, financial and environmental elements at stake with the regulation project on the reduction of pollution originating from agricultural activities. The environmental problems and setback of the control measures are presented. It is stress that environmental problems come particularly from the 3 watersheds (L’Assomption, Yamaska and Chaudiere) where the animal concentration is very high and manure production exceeds the soil baring capacity (in these areas) by 4 millions cubic meters annually which corresponds to 14,000 tons of nitrogen and 7,000 tons of phosphorus spread in excess. Discussions have been made between different organizations and individuals in order to find consensus on the different aspects of the proposed regulation. Many elements from that consultation have been approved and they are: the obligation to have manure and fertilizer management plan developed by an agronomist or by the farmer who would have received specific formation; consider the phosphorus as the limiting element in the soil where its concentration is high; minimum distances from ditches, streams, ponds or lakes for manure application; manure application period; distances for odour control. The regulation of different countries, states in the United States and also provinces in Canada are presented and some comparisons are done with Quebec’s regulation project. An economical evaluation of the impacts of such regulation is presented and the total cost associated is estimated to be 44 M$ per year. On the other hand the savings on commercial fertilizers is estimated to be from 15 to 30 M$ per year and could go as high as 60 M$/year. The nutrients losses to the streams, rivers and lakes are estimated to be reduced by 20,000 tons of nitrogen per year and 3,900 tons of phosphorus, representing 42% and 24% of the actual losses. The improvement of the water quality of many streams and river and the return for recreational use is an important advantage than has no been estimated economically.