Its flow rate has been observed for a period of 40 years at Cheniménil, a locality in the Vosges department situated slightly before its confluence with the Moselle.

The low water for July to September brings the average monthly flow rate down to 3.89 cubic metres per second (137 cu ft/s) in August.

The pearls, rather small, were prized by the bourgeoisie and the nobility up until the 19th century, at which time their rarity caused interest to wane.

This substantial lifetime gives rise to a very slow regeneration rate for the population, which in turn explains the quasi-disappearance of the species owing to fishing, certainly, but also to the pollution of the river by textile factories.

The textile industry itself has now almost disappeared, and while this is a cultural, economic and social setback, it has afforded the Vologne a steady improvement in water quality over recent years.

Its high trout population density won it the right to hold certain rounds of the World Fly Fishing Championships in July 2002.

This valley is flanked by two steep slopes rising from 250 to 300 metres (820 to 980 ft) that are covered from the base to the summit with ancient trees, enormous rocks or scree.

The Vologne flows at the foot of the valley, past naturally growing trees and dark rocks which line its route.

The river, the railway line and the road occupy the bottom of the valley, whose width, at certain places, is no more than 20 to 25 metres (66 to 82 ft); the slopes are so close to each other that the sun can barely penetrate.