The ²¹⁰Pb radiometric dating method was applied in order to determine the sedimentation rates of a northern Danube Delta lake (Merhei Lake) using α and γ spectrometry for assessing the radionuclides of interest. Another objective is to measure the geochronology of each sediment layer and to determine the dynamics of the characteristic sedimentation processes. The Danube Delta is the second largest river delta in Europe, having an approximate surface of 4152 km². The Danube branches into three main distributaries into the delta: Chilia, Sulina and Sfântul Gheorghe. Two sediment cores (one from the close proximity of the estuary and another one from a more secluded area) were taken from a northern lake, namely Merhei Lake, formed between the Chilia and Sulina branches. The sedimentation rate was measured by ²¹⁰Pb using its α emitting progeny, ²¹⁰Po, for determining the solid discharge of the delta branches and, respectively, the spacial and temporal variations; while ²²⁶Ra (determining the supported and unsupported ²¹⁰Pb content of the sediments) was determined using high resolution γ spectrometry. The sediments have been dated up to 1885, having average mass sedimentation rates of 0.30 ± 0.04 g/cm²y and linear sedimentation rates of 0.68 ± 0.18 cm/y. The sediment is transported throughout the lake, so the more secluded part of the lake has at some depths up to twenty times more sediment intake than the one near the estuary.