Phosphorus (P) budget analysis of the 2007 summer limnological data set confirmed that internal P loading, primarily from anaerobic sediments located in the north basin, is the dominant P source driving algal blooms in Big Chetac Lake. Empirical steady-state models predicted that management of internal P loading in the north basin would result in a 47% decrease in mean summer total P concentrations to 0.045 mg/L. Predicted chlorophyll concentrations declined by 60% to 21 μg/L and frequency of nuisance algal blooms (i.e., chlorophyll concentrations > 30 μg/L) decreased from 73% to only 19% of the time during the summer. In contrast, management and reduction of tributary P loads resulted in minor predicted improvements in limnological characteristics because these inputs were low relative to P inputs via internal loads.

Big Chetac Chain Lakes Association is sponsoring a project to assess the feasibility of an alum treatment for Big Chetac Lake. The final deliverables include a final report documenting the results of the regulations review, sediment cores, alum dosage analysis, and lake response modeling.

Alum Feasibility Study

Final Report