Water authorities need to work with other constituencies, including the agriculture and energy sectors, while taking the environment into account, they also need to work at different levels of government (local, basin, municipal, state and federal levels). For example, there has been long-standing co-operation between Canada and the United States through the Canada-US Boundary Waters Treaty and the Canada-US Great Lakes Water Quality Agreement. The United Nations Economic Commission for Europe operates the Convention on the Protection and Use of Transboundary Watercourses and International Lakes, providing an important framework for international co-operation.