| Abstract: | A water-quality investigation of the upper Snake River Basin began in 1991 as part of the U.S. Geological Survey‘s National Water-Quality Assessment Program. Sampling and analysis focused on nutri-ents, suspended sediments, and pesticides. Concentrations of nutrients and suspended sediment in the upper Snake River Basin, in general, increased towards the outlet of the basin. Median concentrations of dissolved nitrite plus nitrate at 19sites ranged from less than 0.05 to 1.60 milligrams per liter; total phosphorus as phosphorus, less than 0.01 to 0.11 milligrams per liter; and suspended sediment, 4 to 72 milligrams per liter. Significantdifferences (p<0.05) in nutrient and suspended sediment concentrations were noted among groups of sites categorized by the quantity of agri-cultural land in their upstream drainage basins. Concentrations of dissolved nitrite plus nitrate were largest during the nonirrigation season, October through March. Concentrations of total phosphorus and suspended sediment, in general, were largest during high streamflow, April through June. The pesticides EPTC (eptam), atrazine, desethylatrazine, metolachlor (dual), and alachlor (lasso) were the most commonly detected in theupper Snake River Basin and accounted for about 75 percent of all pesticide detections. All pesticides detected were at concentrations less than 1 microgram per liter and below maximum contaminant levels established by the U.S. Environmental Protection Agency. The largestnumber and concentrations of pesticides were detected in May and June following early growing season applications. |
| Genre: | USGS Numbered Series |
| ProdID: | 26588 |
| Citation Author: | Clark, G. M. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | vii, 45 p. :ill., maps ;28 cm. |
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| Citation Publisher: | U.S. Geological Survey ;
USGS, Information Services [distributor], |
| Citation Series: | Water-Resources Investigations Report |
| Citation Series Code: | WRI |
| Citation Series Number: | 97-4020 |
| Citation Search Results Text: | Assessment of nutrients, suspended sediment, and pesticides in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1991-95; 1997; WRI; 97-4020; Clark, G. M. |
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| Citation Year: | 1997 |
| Type: | citation/reference |
| Text: | Assessment of nutrients, suspended sediment, and pesticides in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1991-95; 1997; WRI; 97-4020; Clark, G. M. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/wri/1997/4020/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/wri/1997/4020/report.pdf |
| Date Other: | Mon, 1 Dec 1997 00:00 -0600 |
| Publisher: | U.S. Geological Survey ;
USGS, Information Services [distributor], |
