The Ilmenau is a river south of Hamburg in Lower Saxony, Germany. The Ilmenau rises in the Lüneburg Heath south of Uelzen as the confluence of the Gerdau and Stederau rivers in the municipality of Veerssen, Uelzen district. It is a left-hand tributary of the Elbe at Wiesen. The river is 121 km long, including the source river Stederau. The largest towns along the Ilmenau are Uelzen and Lüneburg. Where the town of Ilmenau in Thuringia does not lie along the Ilmenau, but along the Ilm. The river is navigable from Lüneburg, but is used almost exclusively by cruise ships. Above Lüneburg, the river is popular with boaters. On the section from Lüneburg to Hoopte, three locks have to be crossed (at Bardowick, km 5.60, Wittorf, km 12.35 and Fahrenholz, km 17.70).
Each lock is 45 metres long and 6,5 metres wide. The Fahrenholz locks are already under water in the tidal area of the Elbe. Today, the river is of little transport importance. In the past, it provided a connection to the port of Stöckt as a protective harbour for inland waterway vessels and a transhipment port, through which, for example, the wood processing plant in Wiessen (Luhe) was supplied by water. The cruise ship that used to go up and down the river from Lüneburg has also ceased its voyages.
Ilmenau was the main shipping route between Lüneburg and Elbe. Salt, lime, cement and iron goods were mainly imported from Lüneburg, while vegetables, potatoes, hay, straw and manure were imported from Bardowick and the villages below. Fish, grain, peat and textiles were transported upriver from Ilmenau.
