Medan - FKM USU: The training "Application of Geographic Information Systems (GIS) in Water Chemical Analysis" was held by the Tropico Development Center (TDC) FKM USU on 4 - 7 September 2023 at the Grand Impression Hotel Medan. The training, which was attended by 10 (ten) participants from the Balai Teknik Kesehatan Lingkungan dan Pengendalian Penyakit (BTKLPP) Class I Medan, was opened by the Chair of the TDC FKM USU, dr. Fazidah Aguslina, Ph. D. accompanied by the Commitment Making Officer (PPK) BTKLPP Class I Medan, Noviandi, S.Si., M. Kes. Six resource persons participated in this training, namely Dr. Ir. Erna Mutiara, M. Kes., Dr. dr. Taufik Ashar, M.K.M., Ismil Khairi Lubis, S.K.M., M.P.H., Winni R.E. Tumanggor, S.K.M., M.P.H., Arifa Masyitah Panjaitan, S.K.M., M. Kes., and Fitri Khairani, S.S.T., M.K.M. The material presented in this training includes an introduction to GIS, the use of GPS, creating digital maps from spatial data and attributes and statistical spatial analysis. Participants practice directly using the QuantumGIS (QGIS), GPS Essentials and Geoda applications. At the end of the activity, actualization exercises were carried out until participants succeeded in creating a thematic map of water chemistry analysis in Lake Singkarak obtained from secondary data from BTKLPP Class I Medan.