A needle dam is a weir made of wooden poles which can be spaced or removed so that more or less water flows. There are several along the Cher, including the most well known, at Civray de Touraine, just downstream from the Chateau of Chenonceau.
Historically they are important and are now formally protected (since July 2017), but from a nature conservation point of view are problematic. So a solution will be put in place this year at Civray, with a new channel of the river being dug to take migrating fish and canoeists up and down. The old needle dam will remain in place and perform its traditional function of maintaining a suitable depth of water around the Chateau's foundations, which sit in the river.
The lock on the right and the needle dam stretching out across the river.
The needle dams date from the 19th century and there has been at least a decade of wrangling between those who value their heritage and those who want to see migrating fish returning to their ancient freshwater spawning grounds. Anglers, farmers who want to irrigate, boaters and tourist operators are all stakeholders in what happens next, anxious to preserve both heritage and water levels in dry times.
Now it seems both sides can be happy, with an ambitious plan to preserve the dam and the aquatic environment. Diggers have started excavating a bypass of 185 metres long, 6 metres deep and 15 metres wide. This new channel will allow migrating fish such as shad, eel or sea lamprey to pass. It will also facilitate the movement of pike, barbels and other fish. Not to mention canoes and kayaks.
In total, €532 000 will be invested, funded 60% by the Loire-Brittany Water Agency and 20% each by Centre-Val de Loire Region and Indre et Loire County. It is the largest project currently being carried out in France on river ecological continuity. Three other projects of the same kind should be completed in a few years at Savonnières, Ballan-Miré and Saint Aignan.
Note: all photos taken by me in August 2017, before work commenced.
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