Water quality in the eastern Iowa basins, Iowa and Minnesota, 1996-98

Kalkhoff, Stephen J.; Barnes, Kimberlee K.; Becher, Kent D.; Savoca, Mark E.; Schnoebelen, Douglas J.; Sadorf, Eric M.; Porter, Stephen D.; Sullivan, Daniel J.

doi:10.3133/cir1210

Cited by 32 publications

(34 citation statements)

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“…The area is characterized by intensive agricultural activities with corn and soybean as major crops (Kalkhoff et al 2000). Twenty groundwater sampling sites and ten surface water sampling sites were selected and tested from May to September 2006.…”

Section: Study Areamentioning

confidence: 99%

Using stable isotopes of nitrogen to study its source and transformation in a heavily farmed watershed

Gautam

Iqbal

2009

Environ Earth Sci

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Twenty private wells and ten stream locations were sampled to assess the source and fate of dissolved nitrate in the Cedar River watershed of Iowa, USA. The average levels of nitrate in groundwater decreased from 39.5 mg/L in May, to 38 mg/L in July, to 30 mg/L in September. Although several surface water samples exceeded MCL in May, most values dropped to below 20 mg/L by July and September. The decreasing N levels were attributed to the gradual uptake of nitrate by growing crops as well as the cyanobacterial growth in the aquatic systems. The d 15 N values of dissolved nitrate in groundwater ranged from ?0.45 to ?5.35%, whereas those in surface water ranged from ?1.48 to ?5.16%. The results suggested that commercial fertilizers and soil organic nitrogen were probably mixed up in their transport pathways. A fertilizer-only source would provide much lower delta values, whereas soil nitrogen would provide higher than observed delta values. Denitrification was considered unlikely because of the low d 15 N values, high nitrate concentrations, and moderately high DO content in groundwater. Animal wastes were not found as a possible source of nitrate in the water. This is supported by the low chloride concentrations and lower than 10% delta values in the water samples. The study demonstrates that nitrogen isotope data in coordination with the dissolved nitrate levels and land use can be effectively used in nitrogen source identification and its transformation studies.

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Section: Study Areamentioning

confidence: 99%

Using stable isotopes of nitrogen to study its source and transformation in a heavily farmed watershed

Gautam

Iqbal

2009

Environ Earth Sci

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“…In the case of groundwater, nitrate concentrations can generally be expected to decrease with well depth (Rajagopal and Talcott 1983). In a temporal context, high nitrate concentrations are often associated with spring and summer rainfall (Kalkhoff et al 2000). Interannual variability can also impact nitrate concentrations; Randall and Mulla (2001) have observed low nitrate transport during dry years and relatively higher nitrate transport during wet years.…”

Section: Drinking Water Contaminants -Iowa Observationsmentioning

confidence: 97%

“…Earlier studies in Iowa have indicated that the concentration of contaminants (especially, those that are external to the CWS) in ambient source water and treated drinking water is expected to be similar (Rajagopal 1984). As agriculture is the predominant land use in Iowa, major contaminants in Iowa's surface and shallow groundwater are constituents such as nitrates and atrazine (Rajagopal 1984;Rajagopal and Tobin 1989;Natarajan and Rajagopal 1994;Kolpin et al 1996;Kolpin et al 1998;Skopec 1999;Kalkhoff et al 2000). An analysis by Waters et al (1987) indicated that 134 different PWSs in Iowa violated the nitrate MCL at some time during the period 1978-1986.…”

Section: Drinking Water Contaminants -Iowa Observationsmentioning

confidence: 99%

Economics of place-based monitoring under the safe drinking water act, part I: spatial and temporal patterns of contaminants, and design of screening strategies

Brands

Rajagopal

2007

Environ Monit Assess

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The goals of environmental legislation and associated regulations are to protect public health, natural resources, and ecosystems. In this context, monitoring programs should provide timely and relevant information so that the regulatory community can implement legislation in a cost-effective and efficient manner. The Safe Drinking Water Act (SDWA) of 1974 attempts to ensure that public water systems (PWSs) supply safe water to its consumers. As is the case with many other federal environmental statutes, SDWA monitoring has been implemented in relatively uniform fashion across the USA. In this three part series, spatial and temporal patterns in water quality data are utilized to develop, compare, and evaluate the economic performance of alternative place-based monitoring approaches to current monitoring practice. Under the Safe Drinking Water Act (SDWA), a common list of over 90 contaminants is analyzed nationwide using EPA-authorized laboratory procedures. National and state-level summaries of SDWA data have shown that not all contaminants occur in all places at all times. This hypothesis is confirmed and extended by showing that only a few (less than seven) contaminants are of concern in any one of 19 Iowa surface water systems studied. These systems collectively serve about 350,000 people and their sizes vary between 1,200 and 120,000. The distributions of contaminants found in these systems are positively skewed, with many non-detect measurements. A screening strategy to identify such contaminants in individual systems is presented. These findings have significant implications not only for the design of alternative monitoring programs, but also in multi-billion-dollar decisions that influence the course of future drinking water infrastructure, repair, and maintenance investments.

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“…Streamflow at Iowa-1 and -2 is mainly from subsurface (tile) drains, compared to overland flow and groundwater flow contributions to streamflow at Iowa-3 (Simon and Klimt 2008;. Average annual precipitation in the SFIR basin is approximately 800 mm (31.5 in), and about 25% of the precipitation becomes runoff (Kalkhoff et al 2000). The dominant soil association is the Clarion (well-drained Typic Hapludolls), Nicollet (poorly drained Aquic Hapludolls), and Webster (poor drained Aquic Hapludolls; Karlen et al 2008), which is typical of the Des Moines lobe, a landform region in north-central Iowa formed by Wisconsinage glaciation (approximately 12,000 years ago).…”

mentioning

confidence: 99%

Effects of hydrology, watershed size, and agricultural practices on sediment yields in two river basins in Iowa and Mississippi

Merten¹,

Welch²,

Tomer³

2016

Journal of Soil and Water Conservation

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Abstract:The specific sediment yield (SSY) from watersheds is the result of the balance between natural, scale-dependent erosion and deposition processes, but can be greatly altered by human activities. In general, the SSY decreases along the course of a river as sediments are trapped in alluvial plains and other sinks. However, this relation between SSY and basin area can actually be an increasing one when there is a predominance of channel erosion relative to hillslope erosion. The US Geological Survey (USGS) conducted a study of suspended sediment in the Iowa River basin (IRB), Iowa, and the Yazoo River basin (YRB), Mississippi, from 2006 through 2008. Within each river basin, the SSY from four largely agricultural watersheds of various sizes (2.3 to 35,000 km 2 [0.9 to 13,513 mi 2 ]) was investigated. In the smallest watersheds, YRB sites had greater SSY compared to IRB sites due to higher rain erosivity, more erodible soils, more overland flow, and fluvial geomorphological differences. Watersheds in the YRB showed a steady decrease in SSY with increasing drainage basin area, whereas in the IRB, the maximum SSY occurred at the 30 to 500 km 2 (11.6 to 193 mi 2 ) scale. Subsurface tile drainage and limits to channel downcutting restrict the upstream migration of sediment sources in the IRB. Nevertheless, by comparing the SSY-basin size scaling relationships with estimated rates of field erosion under conservation and conventional tillage treatments reported in previous literature, we show evidence that the SSY-basin size relationship in both the IRB and YRB remain impacted by historical erosion rates that occurred prior to conservation efforts.Key words: agriculture-annual sediment loads-scale effect-sediment yield-soil management practices Watershed disturbance by changes in land use, soil management practices, dam construction, and dredging and straightening of channels has resulted in substantial changes in the sediment loads of rivers around the world (Walling 2008). In the United States, changes in sediment load by watershed disturbance have resulted in hydrologic, ecologic, and engineering effects both upstream and downstream (Walling 1999; Horowitz 2010). Changes in land use from forest and prairie to agricultural land during the 19th century accelerated the erosion process, transferring sediment from uplands to valleys and the fluvial system (Trimble 1999). Later, during the 20th century, reservoir construction and soil conservation programs implemented in agricultural areas reduced sediment transference from uplands to rivers and created new, artificial sediment sinks (Renwick et al. 2005). Horowitz (2010) identified the construction of dams on the Missouri River in the late 1950s, and the sediment trapped behind them, as the primary cause of reduced annual suspended sediment loads in the Mississippi River. Nonetheless, Meade and Moody (2010) reported that the MissouriMississippi dams trap only about 1 × 10 8 to 1.5 × 10 8 Mg (1.102 × 10 8 to 1.653 × 10 8 tn) of sediment per year, which is less than h...

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Water quality in the eastern Iowa basins, Iowa and Minnesota, 1996-98

Cited by 32 publications

References 0 publications

Using stable isotopes of nitrogen to study its source and transformation in a heavily farmed watershed

Using stable isotopes of nitrogen to study its source and transformation in a heavily farmed watershed

Economics of place-based monitoring under the safe drinking water act, part I: spatial and temporal patterns of contaminants, and design of screening strategies

Effects of hydrology, watershed size, and agricultural practices on sediment yields in two river basins in Iowa and Mississippi

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