Bleibtreusee, Artificial lake in Rhein-Erft-Kreis, Germany.

Bleibtreusee is an artificial lake of about 74 hectares in the Ville lake chain between Brühl and Hürth, created in 1973 from a former lignite open-pit mine. Its shores lie in Brühl-Heide, Brühl-Kierberg and Hürth-Knapsack. A small elongated island at the southern edge is reserved for breeding birds, including great crested grebes and kingfishers. Windsurfers and small sailing dinghies are allowed on released sections, and a water-ski facility with gastronomy opened at the north end in July 2007 beside a shallow sandy bathing beach.

The lake came into being in 1973 when a former lignite mining pit was filled with water. This transformation turned a worked industrial site into a space for recreation and water activities.

The lake is named after Hermann Bleibtreu (1821–1881), a pioneer of lignite mining around Brühl who opened a mine field south of Heide in 1874. Since July 2007 a water-ski facility with its own restaurant has operated at the northern end, next to the shallow sandy bathing beach. Parts of the shore are left to themselves as nature reserves, where the great crested grebe and kingfisher breed on the small southern island.

The lake lies between Brühl and Hürth, with the northern bay in Hürth-Knapsack, the northeast shore in Brühl-Kierberg and the rest in Brühl-Heide. Large car parks east of the lake are reached via the B 265 (Luxemburger Straße) or from Brühl centre via the L 184 (Theodor-Heuss-Straße). A circuit of the lake is about 5 km, roughly an hour on foot.

The northern shore has a sandy beach with a large lawn for sunbathing and the Sonnendeck beach bar offering food and drinks. This combination makes the northern area a popular spot for a relaxed day by the water.