Near Mannheim, the R. Neckar flows into the Rhine. The source of the Neckar is in the nature reserve Schwenninger Moos in the Black Forest near Villingen-Schwenningen at a height of 706 m over sea level. The R. Neckar is navigable between Plochingen and Mannheim. Ports are located in Plochingen, Stuttgart, Heilbronn and Mannheim. Just as the Rhine, the R. Neckar is subject to numerous uses. The middle and lower course of the Neckar is impounded. The many uses of the river have fundamentally modified the ecology of the water course. Only the upper course of the R. Neckar has largely preserved its natural character.