The Ramganga earth and rock fill dam across the river Ramganga at Kalagarh 125.6m high, 12m wide at the top and is 625. 8m long at its crest, was completed in 1974. The Ramganga Reservoir having a storage capacity of 2.49 x 10m’ was partially filled for the first time during 1974 summer monsoon, The following studies were taken up in order to determine the effect if any of reservoir filling on the seismic activity; (i) the study of six months records of the Kalagarh observatory and (ii) the study through the microearthquake recording at si,te for two months during the 1974 summer monsoon. The first study had its merit in the fact that the recording through conventional type of instruments is available uniformly for several years prior to reservoir filling and has been continued during and after the reservoir filling. The second study was to detect low level seismic activity, which could not be detected by the conventional recording (at limited gain) and is expected to show the effect of reservoir filling, Also, generally small earthquakes are expected to . occur more frequently then the larger ones ond therefore the microearthquake recording spread over even short time intervals permits collection of data on larger number of local events. The seismograms of the Kalagarh observatory for the months of April to September 1974 have been analysed and the results are reported here, Microearthquake recording for 65 days from July 16 to September 19, 1974 has been done by the School of Research and Training in Earthquake Engineering using a sensitive portable seismograph system. The entire details of the work and a discussion of results with the possible conclusions are reported in the paper.