Large parts of the basin in Bulgaria and Greece have been designated as Natura 2000 sites. The Nestos delta, in Greece, has been designated as a Ramsar Site. According to the agreement that was concluded between Bulgaria and Greece in 1995 referring specifically to the Mesta/ Nestos, Bulgaria is obliged to deliver to Greece 29 % of the average run-off of the river generated in the Bulgarian territory. According to Bulgaria concerned by the observed reduction of run-off the actualization of the basis for the calculation is overdue.
