The increase in total phosphorus concentration in the lake has yielded a profound increase in algal abundance. The dense algae that have bloomed in Clear Lake have decreased water clarity to the point that rooted aquatic vegetation has declined substantially. Turbid waters with algae favor the growth of resistant fishes like carp and bullhead that disturb sediments and uproot vegetation. Sediment resuspended by fish and increased wind mixing in the absence of rooted vegetation further decreases water clarity, further reducing the ability of rooted aquatic plants to grow and filter nutrients and stabilize sediments. Resuspended sediments lead to increased phosphorus concentrations that have favored even more algae growth. Projected increases in phosphorus concentrations indicate that, in the absence of remedial measures, Clear Lake will decline in quality and utility as a recreational resource.

Knowledge of the hydraulic and nutrient budgets as well as various limnological details allows for the modeling of future water quality under various scenarios of improved watershed characteristics. Iowa State University analysis suggests that a 60% reduction in total phosphorus loading to Clear Lake should bring water clarity to the 2.5 - 4 foot level, once lake conditions equilibrate. This water clarity level is somewhat conservative because increased water clarity and carp management taken together would greatly reduce suspended solids in the water column, affording even greater increases in water clarity. It is likely, therefore, that such a management scenario could bring water clarity in Clear Lake back to pre-1970 levels, a highly desirable outcome for everyone.