Phosphorus in Connecticut lakes predicted by land use

The concentration of phosphorus in parts per billion (ppb) in 33 Connecticut lakes was predicted from information on land use and simple models for concentration decreases in lakes. The best predictions were obtained from [Formula: see text] where P is the concentration of phosphorus in ppb, Q is the water load on the lake in meters per year, D is the water export from the entire watershed in meters per year, and U, A, and W are the fractions of urban, agricultural, and wooded land, respectively, in the watershed. The phosphorus export coefficients and SEM, estimated by least squares regression, were 170 +/- 21 mg per m(2)/yr for urban, 54 +/- 15 mg per m(2)/yr for agricultural, and 10 +/- 3 mg per m(2)/yr for wooded land. P +/- (SEM) 6.9 ppb was predicted.