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Subsurface drainage is a common practice in many agricultural watersheds in the Mid-Western region of the United States. A typical drainage system in east central Illinois is not spaced in a parallel manner, but the subsurface drain lines are laid out in a random and irregular fashion. These subsurface drain lines most often discharge into numerous man-made drainage channels, which ultimately drain to the rivers and the reservoirs. The Little Vermilion River (LVR) watershed in east central Illinois, USA is an example of a watershed with altered hydrology from subsurface drainage systems. A continuous monitoring study has been conducted from 1991 to 2003 on this watershed to quantify the effects of cropping management...
nthropogenic selenium contamination of aquatic ecosystems was first associated with cooling reservoirs of coal-fired power plants in the late 1970s, and later with drainage water from agricultural irrigation activities in the 1980s. In the 1990s, selenium contamination has been raised as a concern in the recovery of currently endangered fish in the Colorado River system. Widespread contamination from seleniferous drain waters from agriculture has been documented in the upper and lower Colorado River basins. Historically, irrigation started in the upper Colorado River basin in the late 1880s. In the 1930s, selenium concentrations in various drains, tributaries, and major rivers in the upper and lower Colorado River...
A water quality model for subirrigation and subsurface drainage, ADAPT (Agricultural Drainage And Pesticide Transport), was tested with field data collected under various water table management practices near Ames, IA. Atrazine and alachlor concentrations at various soil depths for water table depths of 30, 60, and 90 cm were simulated using ADAPT model for corn growing seasons of 1989 through 1991. Daily pesticide concentrations in groundwater predicted by the model were compared with available observed data for the same site. Predicted values of atrazine and alachlor concentrations in groundwater decreased when shallow water table depths were maintained in the lysimeters. Similar trends were noticed with the observed...
Field surveys were conducted during 1997 and 1998 documenting the distribution and abundance of Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus) in Escalante River tributaries. This documented occurrence of native trout in the Escalante River drainage of southern Utah represents an expansion of the known historic range of this subspecies as reported before the 1990s. We found 5 populations of native trout ranging in biomass from 3.0 to 104.2 kg ha-1 and occupying 13.2 km of stream of 130 km of estimated historic habitat. Current distribution and abundance of Colorado River cutthroat trout were compared to early introductions of nonnative trout stocked for sport fishing purposes. Native cutthroat...
Excess phosphorus (P) in freshwater systems has been associated with eutrophication in agro-ecosystems of the US Midwest and elsewhere. A better understanding of processes regulating both soluble reactive phosphorus (SRP) and total phosphorus (TP) exports to tile-drains is therefore critical to minimize P losses to streams while maintaining crop yield. This paper investigates SRP and TP dynamics at a high temporal resolution during four spring storms in two tile-drains in the US Midwest. Depending on the storm, median concentrations varied between 0.006–0.025 mg/L for SRP and 0.057–0.176 mg/L for TP. For large storms (>6 cm bulk precipitation), for which macropore flow represented between 43 and 50% of total tile-drain...