View Full Table | Close Full ViewTable 1.

Basin characteristics, mean annual discharge (for period from October 2003–September 2004) and base flow index (BFI) values for each of the five study areas (adapted from Domagalski et al. (2008) and Capel et al., (2008)).

 
Leary Weber Ditch Maple Creek Morgan Creek DR2 Valley Creek
Drainage area (km2) 7.5 950 31 5.5 31
Mean annual discharge (m3/s) 0.098 2.0 0.49 0.14 0.28
Base Flow Index† 0.12 0.35 0.45 0.57 0.98
Precipitation (mm) 1109 708 1000 187 762
Climate Humid continental Humid continental Humid subtropical Arid/semiarid Humid continental
Soil series Crosby, Brookston Nora, Moody Sassafrass Warden Antigo-Chetek-Mahtomedi
Soil texture Poorly drained glacial till Aeolian sand, silt, and loess Fine silt loams Well drained sand to clays Well drained glacial outwash
Primary land use Corn and soybeans Corn and soybeans Corn and soybeans Orchards, vineyards, row crops, dairies Row crops, rural residential
Percent Agriculture 97 97 74 89 18
Artificial drainage Yes No No Yes No
Irrigation for agriculture Low Moderate Low High Low
BFI calculations were based on stream flow data from 2002 to 2004.



View Full Table | Close Full ViewTable 2.

Median concentrations (in mg/L) of selected constituents in stream-bed pore water, upland groundwater, tile drains, overland flow, and streams in the five study areas. Most samples were collected from 2002 to 2004. Value in parenthesis indicates the number of observations used to calculate the median.

 
Site Location† NO3 (as N) Ortho-P (as P) pH Dissolved oxygen SiO2 SO4 2−
Leary Weber Ditch, Indiana OV 0.03 (18) 0.28 (18) 7.5 (18) 3.5 (18) 3.1 (18)
GW 1.1 (8) 0.006 (8) 7.2 (8) 5.0 (6) 12 (8) 24 (8)
TD 9.3 (34) 0.006 (29) 7.6 (32) 8.2 (33) 10 (33)
PW <0.04 (51) <0.006 (16) 7.3 (51) 0.8 (48) 13 (16) 32 (16)
SW 6.6 (76) 0.022 (54) 7.7 (68) 9.8 (39) 8.5 (59) 13 (58)
Maple Creek, Nebraska OV 8.3 (30) 0.16 (30) 7.7 (12) 7.8 (4) 9.8 (30) 22 (30)
GW 0.46 (16) 0.25 (16) 6.8 (16) 0.3 (16) 27 (16) 38 (16)
PW 0.48 (49) 0.26 (19) 7.0 (19) 1.9 (19) 29 (19) 37 (19)
SW 3.5 (60) 0.21 (59) 8.2 (58) 9.5 (57) 15 (54) 52 (58)
Morgan Creek, Maryland GW 9.3 (15) <0.006 (15) 4.8 (15) 7.5 (14) 11 (15) 1.1 (15)
RP 9.5 (22) <0.006 (22) 5.0 (22) 4.1 (22) 14 (22) 7.9 (22)
PW <0.04 (34)
SW 2.3 (53) 0.023 (51) 6.7 (50) 6.6 (40) 8.0 (48) 6.8 (52)
DR2, Washington State OV 2.5 (9) 0.097 (9) 7.9 (9) 8.0 (9) 19 (9) 7.6 (9)
GW 6.8 (18) 0.050 (18) 7.4 (18) 2.1 (18) 47 (18) 49 (18)
PW 0.09 (33) 0.057 (33) 8.0 (16) 0.3 (16) 50 (16) 60 (16)
SW 3.3 (57) 0.10 (57) 8.0 (56) 8.4 (56) 34 (57) 41 (57)
Valley Creek, Minnesota GW 5.1 (16) 0.017 (16) 9.2 (6)
SP 7.1 (5) 0.019 (5)
PW 0.70 (38) 0.013 (38)
SW 6.3 (13) 0.032 (13) 7.6 (4)
GW, upland groundwater; OV, overland flow; PW, stream-bed pore water; RP, riparian zone piezometers; SP, springs or seeps; SW, surface water; TD, tile drain.