INDEX TO EVALUATE LAKE RESTORATION

A lake evaluation index (LEI) is proposed to express the overall quality of lake water based on a mathematical combination of the commonly measured limnological variables total phosphorus (TP), total nitrogen (TN), chlorophyll (CA), Secchi depth (SD), dissolved oxygen (DO), and macrophyte coverage (PMAC). Values used in the LEI are averages for the July-August period. Epilimnetic zone concentrations of TP, TN, and CA are calculated. Macrophyte coverage is expressed as the percent of the area which could potentially be occupied actually. A term net DO is calculated by summing the absolute differences between observed and saturated DO for volume increments from surface to bottom, divided by the lake volume. The LEI was developed to express the overall change in water quality that might occur when lakes are restored and to evaluate the effectiveness of varoius treatment methods for a wide variety of lakes.