Runoff, solids, and contaminant losses into surface tile inlets draining lacustrine depressions

Surface the inlets connected to subsurface the lines provide a direct pathway for Pollutants to enter water bodies. This study was conducted to evaluate the quantity and duality of surface runoff entering surface tilt? inlets draining natural depressions of lacustrine landscapes, Surface runoff, solids, and nutrittnt losses via surface tile-inlets in two lacustrine watersheds in the southern Minnesota River Basin were investigated from 1995 to 1998, Tillage and crop relations were: (i) fall NH3-N injection after soybean [Glycine max (L,) Merr,] or navy bean (Phaseolus vulgaris var., vulgaris) harvest and (ii) fall chisel plowing after corn (Zea mays subsp, mays) harvest, followed by spring held cultivation, planting, harrowing, and row cultivation. Maximum annual runoff loss via surface inlets was less than 5 % of annual precipitation, Flow-weighted total P (TP) concentration ranged from 0.2 to 2.9 mg L-1 in snowmelt and 0.7 to 6.5 mg L-1 in rainfall runoff. Nitrate N concentrations were less than 10 mg L-1. Three-year maximum cumulative pollutant lends were: 138 kg ha(-1) total solids (TS), 20 kg ha(-1) chemical oxygen demand (COD), 363 g ha(-1) TP, 205 g ha(-1) dissolved molybdate reactive P (DMRP), 1342 S ha(-1) total dissolved inorganic N (TDIN), and 1126 g ha(-1) nitrate N, Most of the dissolved pollutants were associated with snowmelt runoff and most of the particulate pollutants were associated with major storms. Losses of particulate pollutants via surface the inlets are smaller than expected due to the dynamics of ponding in natural landscape depressions.