WSP10284

• File Number: 8170
• Description: Arkansas Basin Water Quality Issues
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 1/1/1998
• Author: USGS
• Title: Water-Quality Assessment of the Arkansas River Basin - Southeastern Colorado - 1990-93
• Water Supply Pro - Doc Type: Report/Study

0213

31. Graphs showing median fecal-colifonn, fecal-streptococci, and total-colifonn bacteria concentrations and median
fecal-colifonn concentrations by streamflow regime in the Arkansas River, April I 99{}-March 1993.................... 65

TABLES

I. Selected surface-water sites in the Arkansas River Basin and water-quality constituents measured or
analyzed between April 1990 and March 1993 ...................................................................................................... 4
2. Least-squares regression equations for dissolved-solids concentration and specific conductance for selected
sites in the Arkansas River Basin, April I 99{}-March 1993 .................................................................................. 12
3. Least-squares regression equations for hardness and specific conductance for selected sites in the
Arkansas River Basin, April199{}-March 1993..................................................................................................... 14
4. Results of Wilcoxon rank-sum test (I-tailed) of pre-treattnent (April 199{}-March 1992) and
post-treattnent (April I 992-March 1993) instantaneous streamflow and cadmium concentrations at
selected sites in the upper Arkansas River Basin ................................................................................................... 18
5. Number of samples that exceeded acute and chronic cadmium water-quality standards in the
upper Arkansas River, April I 99{}-March 1993..................................................................................................... 19
6. Average percentages of instantaneous streamflow and instantaneous total-recoverable copper load
contributed to the Arkansas River by the upstream main-stem site and the intervening tributaries in the
same reach, April I 99O-March 1993...................................................................................................................... 21
7. Results of Wilcoxon rank-sum test (I-tailed) of pre-treatment (April I 99{}-March 1992) and
post-treatment (April 1992-March 1993) instantaneous streamflow and copper concentrations at
selected sites in the upper Arkansas River Basin ................................................................................................... 22
8. Number of samples that exceeded acute and chronic copper water-quality standards in the upper
Arkansas River, April I 99O-March 1993............................................................................................................... 22
9. Average percentages of instantaneous streamflow and instantaneous total-recoverable iron load contributed
to the Arkansas River by the upstream main-stem site and the intervening tributaries in the same reach,
April 199{}-March 1993 ................................. ........................... ............................................................................ 25
10. Results of Wilcoxon rank-sum test (I-tailed) ofpre-treaunent (April I 99{}-Marcb 1992) and
post-treattnent (April 1992-March 1993) instantaneous streamflow and iron concentrations at
selected sites in the upper Arkansas River Basin ................................................................................................... 25
11. Number of samples that exceeded chronic iron water-quality standards in the upper Arkansas River,

April I 99{}-March 1993 . ........................................... ........................... .................................................................. 26
12. Average percentages of instantaneous streamflow and instantaneous total-recoverable lead load
contributed to the Arkansas River by the upstream main-stem site and the intervening tributaries
in the same reach, April 199{}-March 1993............................................................................................................ 28
13. Results of Wilcoxon rank-sum test (I-tailed) of pre-treattnent (April 199{}-March 1992) and
post-treattnent (April I 992-March 1993) instantaneous streamflow and lead concentrations at
selected sites in the upper Arkansas River Basin ................................................................................................... 29
14. Number of samples that exceeded acute and chronic lead water-quality standards in the
upper Arkansas River, April I 99{}-March 1993..................................................................................................... 29
15. Average percentages of instantaneous streamflow and instantaneous total-recoverable manganese load
contributed to the Arkansas River by the upstream main-stem site and the intervening tributaries in the
same reach, April I 99O-March 1993...................................................................................................................... 32
16. Results of Wilcoxon rank-sum test (I-tailed) of pre-treatment (April I 99{}-March 1992) and
post-treattnent (April 1992-March 1993) instantaneous streamflow and manganese concentrations at
selected sites in the upper Arkansas River Basin ................................................................................................... 32
17. Number of samples that exceeded chronic manganese water-quality standards in the
upper Arkansas River, April I 99{}-March 1993..................................................................................................... 33
18. Average percentages of instantaneous streamflow and instantaneous total-recoverable zinc load
contributed to the Arkansas River by the upstream main-stem site and the intervening tributaries in the
same reach, April 1 99O-March 1993...................................................................................................................... 35
19. Results of Wilcoxon rank-sum test (I-tailed) of pre-treaunent (April 199{}-March 1992) and
post-treatment (April I 992-March 1993) instantaneous streamflow and zinc concentrations at
selected sites in the upper Arkansas River Basin ................................................................................................... 36

CONTENTS V