In Lakes Tiefwaren (TF) and BL the initial age model suggested the presence of peaks of DDT derivatives in the 19 th century. This is inconsistent with loads observed in all other lakes, and with the onset of DDT application in the 20 th century. In addition, Lake TF received a hypolimnic treatment with aluminum between 2001 and 2005 as a restoration measure from eutrophic to mesotrophic states . The original age model would place the Al peak of the treatment to the 1970s. Fallout peaks of 137 Cs in 1986 (Chernobyl disaster) and 1962/63 (peak of nuclear bomb tests in the high atmosphere) were re-evaluated, and adjusted the age model after considering these inconsistencies (Fig. ).