Until the beginning of the 19th century, the Rhine could still change with natural dynamics. This means that it kept changing its course, which led to the formation of Rhine oxbow lakes and flood channels. Millinger Sea, Hurler Sea, Empel Sea and the Bienen Old Rhine were formed from such shifts in the course of the Rhine. The Bienen Old Rhine originated in the 14th century and, in the early 16th century, was cut off from the main Rhine which was now much further away. As a result of being cut off, the once five-metre-deep Rhine oxbow lake slit up and in 1982 was less than one metre deep in places. To conserve the Old Rhine, it was dredged partially in the same year, with the result that afterwards the average depth was 2.50 m again there.
In the south, borders the “Rosau” that is also part of the area. This oxbow lake has a slightly different genesis. This part was not originally an oxbow lake that permanently carried water but was deepened by several floods. Unlike the other oxbow lakes in the region, it does not have a sealing layer of mud, but is connected to the groundwater. For this reason, its water levels fluctuate more than those of the northern Bienen Old Rhine.