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9.
<br />Statistical summary of nutrient concentrations at selected surface -water sites with at least 40
<br />observations in the South Platte River Basin, water years 1980 -92 ......................................... ...............................
<br />5C
<br />10.
<br />Results of seasonal Kendall tests for time trends for flow adjusted concentrations of selected nutrients
<br />at selected surface -water sites in the South Platte River Basin ................................................ ...............................
<br />63
<br />11.
<br />Estimated annual nutrient loads at selected sites in the South Platte River Basin, for low flow
<br />(water year 1981), median flow (water year 1986), and high flow (water year 1983) ............. ...............................
<br />68
<br />12.
<br />Number of dissolved nitrite plus nitrate, as nitrogen, samples not meeting water - quality criteria in water
<br />from selected wells in the South Platte River Basin, water years 1980 -92 ............................. ...............................
<br />74
<br />13.
<br />Site and basin characteristics of surface -water sites that have sediment data in the South Platte
<br />RiverBasin, water years 1980 -92 ........................................................................................... ...............................
<br />82
<br />14.
<br />Number of samples taken in each particle -size fraction and percent sand at surface -water sites that
<br />have sediment data in the South Platte River Basin, water years 1980 -92 .............................. ...............................
<br />85
<br />15.
<br />Summary statistics of suspended- sediment concentrations, by land use, in the South Platte River Basin,
<br />wateryears 1980 -92 ................................................................................................................ ...............................
<br />87
<br />16.
<br />Stream locations where pesticide samples were collected in the South Platte River Basin,
<br />wateryears 1980 -92 ................................................................................................................ ...............................
<br />92
<br />17.
<br />Number of pesticide samples collected from surface -water sites, by land use and compound class, in the
<br />South Platte River Basin, water years 1980 -92 ....................................................................... ...............................
<br />94
<br />18.
<br />Number of analyses available in the National Water Information System (NWIS) and
<br />Storage and Retrieval (STORET) data bases for the most commonly applied pesticides in the South Platte
<br />RiverBasin, water years 1980 -92 ............................................................................................. ...............................
<br />94
<br />19.
<br />Distribution of pesticide samples, by month, at selected surface -water sites in the South Platte
<br />RiverBasin, water years 1980 -92 ........................................................................................... ...............................
<br />95
<br />20.
<br />Number of pesticide samples, by decile of flow, at selected surface -water sites in the South Platte
<br />RiverBasin, water years 1980 -92 ............................................................................................ ...............................
<br />95
<br />21.
<br />Number of wells that have pesticide data, by aquifer and well type, in the South Platte River Basin,
<br />wateryears 1980 -92 ................................................................................................................ ...............................
<br />96
<br />22.
<br />Pesticide samples from wells, by land use and compound class, in the South Platte alluvial aquifer,
<br />wateryears 1980 -92 ................................................................................................................ ...............................
<br />96
<br />23.
<br />Percentage of detections and median concentrations for selected pesticides in surface water, by land use, in the
<br />South Platte River Basin, water years 1980 -92 ....................................................................... ...............................
<br />97
<br />24.
<br />Pesticides detected in surface water in the South Platte River Basin, water years 1980 -92 ..... ...............................
<br />100
<br />25.
<br />Percentage of detections and median concentrations for selected pesticides in ground water, by aquifer, well type,
<br />and land use in the alluvial aquifer, in the South Platte River Basin, water years 1980 -92 .... ...............................
<br />104
<br />26.
<br />Pesticides detected in ground water in the South Platte River Basin, water years 1980 -92 .... ...............................
<br />105
<br />27.
<br />Streamflow statistics and period of record for surface -water sites with more than 10 years of record
<br />inthe South Platte River Basin .................................................................................................. ...............................
<br />112
<br />28.
<br />Harvested acreage for selected crops in the South Platte River Basin, 1991 ............................ ...............................
<br />113
<br />29.
<br />Approximate planting dates, days to harvest, and application rates and timing of fertilizers and pesticides
<br />for selected crops in the South Platte River Basin ................................................................... ...............................
<br />116
<br />30.
<br />Herbicides applied annually from 1987 to 1989, by county, South Platte River Basin ............ ...............................
<br />118
<br />31.
<br />Common name, trade name, compound class, and typical application of pesticides commonly used in the
<br />SouthPlatte River Basin ........................................................................................................... ...............................
<br />122
<br />32.
<br />Estimated chemical fertilizer application in the South Platte River Basin, water year 1991 ... ...............................
<br />124
<br />33.
<br />Number of surface -water nutrient samples by site and decile of flow in the South Platte River Basin,
<br />wateryears 1980 -92 ................................................................................................................ ...............................
<br />125
<br />34.
<br />Number of surface—water nutrient samples by site and month in the South Platte River Basin,
<br />wateryears 1980 -92 ................................................................................................................ ...............................
<br />130
<br />35.
<br />Regression coefficients and associated probability values of models used to estimate nutrient loads for
<br />selected sites in the South Platte River Basin, water years 1980 -92 ....................................... ...............................
<br />143
<br />A CONTENTS
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