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

Surface the inlets connected to subsurface the lines provide a direct pathw ay for Pollutants to enter water bodies. This study was conducted to evalua te the quantity and duality of surface runoff entering surface tilt? inlets draining natural depressions of lacustrine landscapes, Surface runoff, sol ids, and nutrittnt losses via surface tile-inlets in two lacustrine watersh eds in the southern Minnesota River Basin were investigated from 1995 to 19 98, 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) harv est, followed by spring held cultivation, planting, harrowing, and row cult ivation. 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. Ni trate N concentrations were less than 10 mg L-1. Three-year maximum cumulat ive pollutant lends were: 138 kg ha(-1) total solids (TS), 20 kg ha(-1) che mical oxygen demand (COD), 363 g ha(-1) TP, 205 g ha(-1) dissolved molybdat e 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 w ith 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 landsca pe depressions.