 Complete the following phrase:  Since the early 2000s, Belgrade plutocracy began building summer houses on the bank, in the protected zone despite the ban. Originally those were smaller, wooden houses but in time, as there was no official reaction, the construction of the proper multi-floor houses and villas with private peers on the river began. Owners of the villas include politicians, judges, managers of the state owned companies and known criminals. Use of heavy building machinery and trucks deteriorated the embankment itself, while the forests in the riparian zone were cut in order to fill the building ground with additional earth and gravel. That way, the riparian zone was elevated, stultifying its existence, as the area ready to accept the excess waters during floods was reduced. Another problem caused by the houses is possible contamination of 16 Ranney collectors in this area, which are part of Belgrades water supply system. The houses also physically obstruct access to the wells for the communal services. None of the floods that hit Serbia since then, including the massive 2009 European floods and 