Réserve naturelle régionale de Lachaussée: A Detailed Geographic Atlas of Protected Wetlands

The defining historical event of the site is the creation of the Étang de Lachaussée itself. In 1273, Count Thiébaut II of Bar ordered the construction of a dam whose eventual height caused the flooding that submerged four hamlets in the surrounding countryside. From that moment, the lake became a fixed feature of the Woëvre landscape, and the village of Lachaussée took shape at the foot of the embankment, taking its name from the chaussée, the historic name for the raised dam structure.

The pond and its surrounding estate were held for several centuries by the noble Wangen family. Christian de Wangen von Gerolsdeck (1900 to 1983) donated the property in 1978, transferring long-standing stewardship into a new phase. The traditional autumn net fishery, conducted from mid-October to mid-November each year and historically enacted with the participation of local villagers who dragged the nets before the fish were sold, remains a living cultural thread that the current owners continue to honor. Today the estate is operated by the Association des paralysés de France, which runs the Domaine du Vieux Moulin with activities including food service, accommodation, and the sale of local products.

From an ecological and legal standpoint, the site's modern protection history began before its formal reserve status. The Étang de Lachaussée and its surroundings were inscribed as a French national scenic site by ministerial order in 1981, recognized under the Ramsar Convention in April 1992, and included in the Natura 2000 ecological network in 1995. The Regional Nature Reserve itself was established on 27 November 2009 by a deliberation of the Regional Council of Lorraine for an initial twelve-year term, and a management plan validated in December 2014 guides the site's conservation for a six-year cycle.

The reserve's ecological identity is woven from a tight mosaic of aquatic, marshland, forest, and agricultural habitats typical of the Woëvre. Open water gives way to extensive reedbeds, then to wet woodland dominated by oak and other broadleaved trees, and finally to damper meadows and cultivated parcels. This sequence of habitats, repeated in slightly different combinations across the region's network of ponds, is what gives the Woëvre its exceptional value for biodiversity.

Vegetation in the reedbeds includes species such as the greater spearwort, the marsh ragwort, and the fringed water-lily, while submerged and shoreline floras include grasses-leaved water-plantain, sharp-leaved pondweed, marsh germander, and pennyroyal. The Bohemian sedge and other characteristic wet-grassland plants round out a flora adapted to fluctuating water levels. The result is a vegetation pattern in which aquatic species, marsh forbs, and water-tolerant trees coexist over short distances, producing high local ecological diversity within a comparatively compact area.

The reserve is internationally significant for birds, with more than 200 observable species reported. Breeding and visiting species include the red kite, the Eurasian bittern, the little bittern, the purple heron, the spotted crake, and the common crane, with the latter using the site during migration. The pond and reedbeds also support a wide spectrum of other waterbirds and marshland passerines, contributing to the site's strong ornithological profile within the broader Woëvre system.

Beyond birds, the reserve harbors a varied amphibian community that includes the European tree frog and the great crested newt, both species strongly tied to high-quality wetland mosaics. Dragonflies are exceptionally well represented, with the emperor dragonfly and the white-tailed darter among notable species, and more than thirty butterfly species have been recorded, including the threatened large copper. Mammals include the wildcat and a noteworthy bat community that includes the common noctule, the western barbastelle, the lesser and greater horseshoe bats, the greater mouse-eared bat, long-eared bats, and Geoffroy's bat, reinforcing the reserve's value as a refuge for fauna sensitive to disturbance and habitat continuity.

The reserve embodies a layered conservation story in which a single site accumulates recognition under multiple frameworks over time. The Étang de Lachaussée and its surroundings were inscribed as a national scenic site in 1981, designated under the Ramsar Convention in April 1992, and incorporated into the Natura 2000 ecological network in 1995. Its Regional Nature Reserve status, granted in 2009, added a dedicated management-oriented layer with a binding plan adopted in December 2014.

From a biodiversity perspective, the reserve's conservation importance rests on the unusual concentration of breeding, wintering, and migratory waterbirds it supports, the integrity of its reedbed and wet-forest mosaic, and the presence of endangered or sensitive species such as the large copper butterfly, the white-tailed darter dragonfly, and multiple bat and amphibian species. Active management is multi-institutional, with the Conservatoire d'espaces naturels de Lorraine providing regional coordination alongside the commune of Lachaussée and the Association des paralysés de France as co-owners. The use of a Konik polski herd to graze key zones reflects a practical, low-mechanization strategy to maintain open wetland habitats within a working estate.

The Lachaussée landscape is inseparable from the human history of the Woëvre. The pond itself is an artifact of thirteen-century territorial planning, and the village of Lachaussée literally takes its name from the dam (chaussée) that created it after four earlier hamlets were submerged. This long history of human-engineered water management pre-dates modern conservation by hundreds of years and gives the reserve a distinctive cultural depth.

A noble stewardship tradition, most recently embodied by the Wangen family and culminating in Christian de Wangen von Gerolsdeck's 1978 donation of the estate, ties the present-day reserve to inherited land-practice. The annual autumn net fishery, once carried out with the help of villagers, is preserved as a living tradition, and the current operation by the Association des paralysés de France extends the site's social role through hospitality, catering, and the promotion of local products at the Domaine du Vieux Moulin.

The reserve's standout features form a compact but rich set: a thirteen-century, man-made pond of roughly 300 hectares that anchors the protected area; one of the most bird-rich inland wetlands in Lorraine, with more than 200 observable avian species; rare specialist invertebrates including the white-tailed darter dragonfly and the large copper butterfly; a multi-layered status as a Ramsar site, a Natura 2000 site, and a former national scenic site, all under one Regional Nature Reserve umbrella; and a working cultural landscape that pairs active ecological management with cycles such as the traditional autumn net fishery and the seasonal grazing of Konik polski horses.

Seasonality strongly influences the experience of the Lachaussée reserve. Spring and early summer are typically the most rewarding periods for birdwatching, when reedbeds host breeding herons, bitterns, and crakes and amphibians such as the European tree frog are most visible around ponds and wet woodland. Migratory cranes and other passage species can also be encountered in spring.

Autumn brings its own distinctive atmosphere. The traditional net fishery takes place from mid-October to mid-November, transforming the pond into a working landscape and combining ecological observation with cultural heritage. Cooler autumn light also enhances the visual contrast between open water, reedbeds, and the surrounding oak woodlands. Winter visits are appealing for observing waterbird assemblages, while summer offers the richest dragonfly and butterfly activity, though reedbed access may feel more enclosed.