This study evaluated several habitat features relative to the natural distribution of Eurasian watermilfoil (Myriophyllum spicatumL.) in Lake Wingra, Wisconsin, using data collected in 1970, when the biomass of this macrophyte was near its historic peak in the lake. Water depth, biomass of other species, and the extinction coefficient of light, in that order, were significant factors for predicting milfoil biomass. Because of multiple correlations between factors, these parameters were probably also acting as surrogate representatives for other factors. A linear regression model for predicting milfoil biomass was weak, but optimal ranges of water depth, substrate organic matter, and substrate texture for milfoil growth were identified.