In 1837, construction began in three places. The river bed was laid by hand to a width of 20 meters and the dams were raised to a height of six meters above the river bed. Women were also used as workers, carrying the earth in baskets. In 1843, the 12.5 km long canal between Riegel and the mouth of the canal in the Rhine was handed over to its intended use.
At 693,000 guilders, the actual costs were far higher than the estimate, so that the “competitor” municipalities had to take out a loan of 400,000 guilders from the Badische Versorgungsanstalt in Karlsruhe. This caused resentment in the communities at times, which died down when the northern Breisgau was spared the floods of the extreme floods of 1844 and 1845 for the first time.
On November 15, 1846, the "Noth Canal Project" was named after Grand Duke Leopold. On this day, an obelisk commemorating the construction of the Leopold Canal was unveiled at the point in Riegel where the “Alte Elz” exits the Leopold Canal. It bears the following inscription:
"To ward off the devastating floods of the Dreisam and Elz, these canals were built under the blessed government of Grand Duke Leopold by the combined forces of the state and the communities involved between 1837 and 1842.
The grateful communities of Neuershausen Hecklingen Boetzingen Kenzingen Eichstetten Herbolsheim Nimburg Oberhausen Bahlingen Niederhausen Koendringen Rust Malterdingen Ringsheim Riegel Kappel 1846 to the Grand Duke Leopold