In the framework of the Bedretto Reservoir Project a medium scale reservoir is created. This means that two boreholes will be connected by fractures to allow water circulation from one borehole to the other. In order to observe the processes during fracture generation and water circulation in detail, the rock volume is monitored using a variety of instruments. Several sensors were newly developed under the lead of Dr. Katrin Plenkers to meet the harsh conditions in the Bedretto laboratory. In summer 2020 and 2021 an expert team has installed the monitoring system in the monitoring boreholes of 101 meters to 300 meters length.