Figure 2 . The spatial pattern of stream nitrate (NO3-N) concentration under Ag (agriculture, 61 sites), Mixed (Ag + other land use, 78 sites), Undev (Undeveloped, pristine, 49 sites), and Urban (40 sites) conditions. Please refer to Detailed Methods for the classification of land uses. Compared to undeveloped sites, agricultural lands generally have elevated stream water concentrations by more than one order of magnitude.