On November 4-5, 2020, the first expedition to the selected lakes was organised. The project experts (Jūratė Kriaučiūnienė, Diana Šarauskienė, Diana Meilutytė-Lukauskienė, Vytautas Akstinas, Aldona Jurgelėnaitė, and Darius Jakimavičius) from Lithuanian Energy Institute surveyed Ilgė, Laukesa, Šalna, Kampiniškiai, and Skirnas lakes. During this expedition, river outflow and inflow from/to the lakes were evaluated, and the most significant tributaries were selected for more detailed investigation. The Laukesa River that flows through Lake Laukesa and forms the natural border between Lithuania and Latvia has been chosen for the close field examination of its hydrological regime.