The European Standard EN 16039:2011 provides guidelines for assessing lake hydromorphology within the Water Framework Directive and includes methods for estimating volume, mean depth, and maximum depth based on statistical models applied to data from topographic maps. We tested the predictive accuracy of these models using independently collected bathymetric data from 35 Swedish lakes. The models had no predictive power, and the maximum depth predictions were inversely correlated with the observed values. The mean absolute percent error was 46% for volume and mean depth, and 85% for maximum depth. The models are flawed and should not be used.