Each (Ec x Area) term represents the amount of phosphorus entering the lake from one particular land use type.
	Ec stands for Export Coefficient, and is an estimation of the amount of phosphorus that a particular land use type contributes to the lake, measured in kg/ha/yr.  We determined a high and low estimate for each export coefficient based on past studies, and determined a best estimate based on specific characteristics of the watershed.
	By multiplying the export coefficients by the area of each land use type, we were able to calculate the amount of phosphorus entering China Lake from each specific land use type.