They have produced local benefits but they have fallen short of the overall goal of improving water quality throughout the system and in the Great Lakes. Partly this is attributable to the changing climate, which has produced more frequent and intensive rainfall events, and to longer exposure of soils to the elements during the shorter duration of snow cover in the period when crop cover is absent.
Cet échec est attribuable en partie au changement climatique, qui entraîne des pluies plus fréquentes et fortes, et à l’exposition plus longue des sols aux éléments, les terres non protégées d’un couvert végétal étant moins longtemps sous la neige.
