Lake Eymir (area: 1–1.3 km2, average depth: 3.2 m, maximum depth) and Lake Mogan (area: 5.6–8 km2, average depth: 2.4 m, maximum depth: 2.8–5.3 m) are connected alkaline lakes (average alkalinity> 6.5 meq / L for both lakes). Lake Eymir (39◦570 N, 32◦530 E) and Lake Mogan (39◦470 N, 32◦470 E) are at 20 km south of Ankara, Turkey and at an altitude of 970 meters and Lake Eymir located in Middle East Technical University campus since 1956. In 1997, Lake Mogan was abundant in aquatic plants and had low chlorophyll-a (Chl-a) values (8.8 ± 2 µg/L) and average total phosphorus (TP) concentration (63 ± 5 µg/L). Lake Eymir was clean enough to meet the drinking water needs of Middle East Technical University before 1970s. However, between 1970 and 1995, there was a deterioration in water quality in both lakes by the introduction of untreated sewage into the lakes. In 1995, a system was established for the treatment of waste water, and the wastes of a few restaurants around Lake Mogan were controlled and the phosphorus input was reduced by 88% by then. Lake Eymir and Mogan ecological monitoring research programme was continued for 23 years by METU-Limnology Laboratory and Ecosystem Research and Implementation Center (EKOSAM) and it is the first and only long-term and continuous work for freshwater research done in Turkey. Thanks to these studies, effective restoration studies have been carried out to reduce eutrophication in these lakes. Hydrological data, which are very important for lake ecosystems, could be followed in detail by these long-term studies. Moreover, a high frequency automated system was established in Lake Eymir in 2015.