Article11 of the Additional Act of the Treaty of Bayonne

Article XI. If one of the two States proposes to carry out works or new concessions that might alter the rate of flow or volume of a waterway whose waters are utilized further down or on the opposite side by riverains of the other country, notice shall be given in
advance to the higher administrative authority of the province or department to which such riverains belong by the corresponding authority in whose jurisdiction the execution of the project is contemplated, in order that, if it is detrimental to the rights of the riverains of the neighbouring sovereignty, it will be possible to protest in due time to the proper quarter and safeguard the interests that might be compromised on both sides. If the works or concessions are to take place in a municipal district contiguous to the frontier, then, along with the persons in charge in one State, the engineers of the other State shall also have the right to take part in the local inspection, being notified for that purpose duly in advance.