Aquatic beetles were sampled on a monthly basis between July 1991 and June 1992 in the wetland pond of La Nava de Fuentes (Palencia), a rehabilitated wetland intended to restore just part of the ancient Laguna de La Nava, one of the biggest wet areas in continental Spain until its virtual disappearance in the 1950s. The ecology and the phenology of 50 species are described, and discussed to determine the degree of maturity reached by this newly created wetland.