Regression relationships were developed between summer mean total phosphorus (P) concentrations in near‐surface water and both chlorophyll a concentrations and Secchi disc transparency for Puget Sound region lakes. Total P concentrations in the lakes studied ranged from 7 to 66 μ/L. The relationship between total P and chlorophyll a, based on data from 69 lakes, explained 57 percent of the variance in chlorophyll a. Predicted chlorophyll a concentrations and 95 percent confidence intervals ranged from 1 +3‐0.5μg/L for 7 μg/L P to about +35‐10μ/L for 66 μ/L P. The relationship between total P and Secchi disc, based on data from 71 lakes, explained 53 percent of the variance in Secchi disc. Predicted Secchi disc transparencies and 95 percent confidence intervals ranged from 5.5 +5.5‐3.0 m for 7 μ/L P to 1.4 +1.5‐0.7 m for 66 μ/L P.