[en] The organic-rich sediments from the centres of Canadian lakes are a valuable sampling medium in the search for uranium. However, because of the young age of hydromorphically transported uranium in these sediments, which must post-date the last period of glaciation, there has been insufficient time for the isotope ²¹⁴Bi to reach equilibrium with its ancestor ²³⁸U. This results in equivalent uranium (eU) values significantly lower than actual uranium values determined by fluorometry or delayed neutron activation analysis. Radiometric (²²⁶Ra) analyses of 12 centre-lake sediments from Seahorse Lake, Saskatchewan illustrate the potential pitfalls which may be encountered using gamma-ray spectrometry, as only 3-8% of the actual uranium present in most of the samples would have been detected. (author)