A study of the physical, chemical, and biological characteristics of Ross Lake in 1975 showed that the lake has no well-defined surface-water inflow and that thermal stratification is well established in summer. The water is of a calcium bicarbonate type, which is typical of lakes in western Washington.
Biological productivity in the lake was low, as indicated by low to moderate chlorophyll a concentrations, by the general lack of submersed plants on the lake bottom, and by the moderate dissolved-oxygen depletion in the deeper zones during thermal stratification. The productivity probably was limited by the amount of phosphorus available. Increased productivity and the resulting growth of nuisance plants can be avoided by limiting phosphate inputs to the lake to their present or lesser rates.