Have you ever imagined gliding silently along a waterway steeped in history? Welcome to the Ginsheimer Altrhein. Right here before us lies a 63-kilometer-long oxbow lake a relic of the Rhine’s past. This isn’t just any old river arm. The Ginsheimer Altrhein boasts a rich history stretching back centuries.
The Ginsheimer Altrhein once held a different name Langenauer Rhein or Der kleine Rhein. It’s a crucial part of the FFH area Ginsheimer Altrhein and the Vogelschutzgebiet Mainmündung und Ginsheimer Altrhein. Imagine the diverse wildlife thriving in this protected environment.
The Ginsheimer Altrhein branches off from the Rhine at kilometer 487.0 opposite the Nackenheimer islands Kisselwörth and Sändchen. A control structure regulates water flow. Originally two pipes channeled Rhine water into the Altrhein. Later a larger channel was added further upstream. The dam has a gentle slope of about 50 centimeters.
For the first two kilometers the Ginsheimer Altrhein meanders parallel to the Rhine. Then it straights out. After five kilometers it reaches Ginsheim. From Ginsheim it flows back to the main Rhine just half a kilometer above the Weisenauer Bridge at kilometer 492.9.
The upper section of the Ginsheimer Altrhein near Ginsheim is a protected nature reserve. It’s closed to boat traffic for two months each year from April 15th to protect nesting birds. The Altrhein is prone to silting and drying up in the upper sections during low water. However it’s artificially deepened below Ginsheim. Even during low water motorboats can navigate this section. Larger vessels also use the lower section between Ginsheim and the Rhine.
A canoe club and a motorboat marina are located in Ginsheim. The Johanna ferry connects the mainland with the Nonnenaue island. Two small islands dot the Ginsheimer Altrhein. One is just below the dam the other about two kilometers downstream.
The current is weak in the upper kilometer but hardly noticeable further down. The island side is natural with extensive willow stands and reed beds. The mainland side is partly reinforced with water blocks.
In the middle ages the Bohemian castle of Astheim stood on the east bank. At its peak from the middle ages to the 19th century as many as 21 shipmills operated near Ginsheim. The remains of a pumping station a kilometer below the dam show where several drainage ditches from the Hessian Ried once flowed into the Altrhein. Today these ditches empty into the Altrhein at a new pumping station near the second island. The Schwarzbach is the largest tributary flowing into the Ginsheimer Altrhein. It drains a large area south of Frankfurt Offenbach and Darmstadt.
The island formed by the Altrhein and the main Rhine is called Langenau in the south and Nonnenaue in the north. Many fish species have returned to the Altrhein including European eel perch bream chub pike crucian carp asp roach rudd tench catfish and zander. The Ginsheimer Altrhein a place of natural beauty and historical significance. A true hidden gem in Mainz.