Higgins Lake remains an oligotrophic lake of high water quality. Both deep basins studied have high year-round dissolved oxygen concentrations throughout the water column, deep light penetration, and low nutrient and chlorophyll-a concentrations. The plankton community also contains biological indicator species, such as the calanoid copepod Senecella calanoides, which are indicative of oligotrophy. The North Basin of Higgins Lake has slightly higher water quality than the South Basin, which, because of its morphometry and location, may be particularly sensitive to eutrophication in the future. Analysis of nitrogen:phosphorus ratios indicates that both basins are phosphorus-limited during mid-summer. In contrast to the deep basins, nearshore areas of Higgins Lake have consistently high concentrations of phosphorus, and heavy accumulations of both marl and the filamentous green alga Cladophora glomerata at many locations. Inorganic nitrogen (especially nitrate) is depleted to potentially limiting levels. An in situ biostimulation experiment, conducted at one of the 18 nearhsore sampling locations, provides confirmation that the growth of algal periphyton nearshore is nitrogen-limited by mid-summer, apparently owing to high phosphorus loading. It is suggested that water quality be managed by reducing human sources of phosphorus, particularly from riparian land, and that further development of the Higgins Lake watershed be considered carefully with regard to its impact upon nutrient loading to the lake.