Figure S3. Shallow water (Csw) and deep water (Cdw) nitrate concentration as a function of percent of agricultural land (81 sites). The solid gray line is the exponential fit while dashed lines are upper and lower bounds at the confidence interval of 95%. Note that filled circles are estimated end-member concentration from high-frequency stream nitrate (Cstream, see Methods) while stars are direct field measurements of Csw and Cdw from intensively studied sites.