Emssperrwerk, Flood barrier between Jemgum and Moormerland, Germany.

The Emssperrwerk is a flood defense structure on the Ems River that uses several large gates to control water flow between the river and the North Sea. The construction consists of seven gates of varying sizes, with the central one designed to allow passage for large vessels.

Planning began in March 1997 after Meyer Werft complained it could no longer move ever-larger ships down the Ems; in 1996 Premier Gerhard Schröder chose a barrier over dredging. Construction ran from 14 September 1998 to 2002, with a court-ordered halt in 1998. Schröder and Premier Sigmar Gabriel opened it on 6 September 2002; the first ship through was the Norwegian Dawn that November.

The barrier is named after the Ems river and is known in Dutch as the Eemskering. Its use is tied to the Meyer Werft in Papenburg: since 2002 the barrier has been closed to dam the river for 43 ship transfers, the first being the 294-metre Norwegian Dawn in November 2002. The legal limit for water retention is 104 hours per year, with a maximum height of 2.70 metres above sea level, and only in winter.

The barrier is located between Gandersum on the north bank and Nendorp on the south bank, about 15 km upstream from Emden. The structure is not open to the public; viewing is possible from the dikes and the adjacent road. The gates are closed only during storm surges or for ship transfers, which are announced in advance.

The central opening spans approximately 60 meters and was specifically designed for large ships built by the region's shipbuilding industry. This size allows ocean-going vessels to travel upriver for construction or repair work.