Willies Val Joly Wastewater Treatment Plant, Willies, Hauts-de-France

The Willies Val Joly wastewater treatment plant is located in the commune of Willies, within the Avesnes-sur-Helpe arrondissement of the Nord department in Hauts-de-France, France. It serves a population of 756 residents and is situated in a rural area near the Val Joly reservoir, a popular recreational lake. The plant is part of the municipal wastewater infrastructure managed by local authorities. The plant operates with secondary treatment, which is the standard level required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations with a population equivalent between 2,000 and 10,000. Although the population served is below this threshold, the plant's design capacity of 5,000 m³/day suggests it is sized to accommodate seasonal variations or future growth. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The treated effluent is discharged into the local watershed, which ultimately drains into the Scheldt River basin via the Helpe Majeure and Sambre rivers. The Val Joly reservoir, a man-made lake created for hydroelectricity and recreation, is a key feature of the area. The plant plays a crucial role in protecting the water quality of this sensitive aquatic environment, supporting biodiversity and recreational uses.

The plant discharges into the Helpe Majeure River, a tributary of the Sambre, which flows into the Meuse River and eventually reaches the North Sea. The Val Joly reservoir, located nearby, is an ecologically sensitive area that supports diverse aquatic life and serves as a migratory corridor for birds. The plant's secondary treatment helps reduce nutrient loads, protecting downstream water quality in this rural, forested region of Hauts-de-France.