Cumulative effects of land use practices on water quality

Water samples were collected bi-weekly along a first- to fifth-order stream gradient, and landscape variables were mapped for the contributing watersheds above each station. Water quality was high under baseflow conditions in the predominantly forested study area, with solute concentrations usually less than 1 mg l^-1 and turbidity values less than 3 NTU, with small, consistent increases downstream. In contrast, large, steep gradients in water quality parameters were observed under stormflow conditions, in some cases increasing three- to six-fold. A numebr of water quality parameters (Cl^-, K⁺, Na⁺ Ca⁺, Mg⁺, SO₄ ^2-, SiO₂, turbidity, faecal streptococcus, and faecal coliform) exhibited significant linear relationships with several landscape variables (percent non-forest, structure density, and paved road density). -from Authors