Table 3–1. Detailed water-quality trend results (not flow adjusted) for the adit sites in the Boulder River watershed, Montana, 

based on analysis of data collected during water years 1999–2013.

[Water year is the 12-month period from October 1 through September 30 and is designated by the year in which it ends. Values in parentheses indicate 

p-values for associated percent change. Gray shading indicates statistical significance (p-value less than 0.01 for trends). p-value, statistical probability 

level; SEE, standard error of estimate; <, less than]

Constituent or property Number of 

samples

Percent 

censored 

values

Trend-analysis 

period, 

decimal years

Trend, 

percent change 

in trend-analysis 

period

Trend, 

percent change 

per year

SEE

Bullion Mine adit (site 2, fig. 1, table 1)

Specific conductance 52 0.0 2003.5–2013.75 -16 (0.086) -1.6 21.5

Cadmium, filtered 54 0.0 2003.5–2013.75 -15 (0.178) -1.6 28.5

Cadmium, unfiltered-recoverable 24 0.0 2008.3–2013.75 -41 (0.034) -9.2 39.9

Copper, filtered 54 0.0 2003.5–2013.75 -33 (0.068) -3.9 53.2

Copper, unfiltered-recoverable 24 0.0 2008.3–2013.75 -51 (0.057) -12 64.7

Lead, filtered 54 0.0 2003.5–2013.75 -20 (0.100) -2.1 30.9

Lead, unfiltered-recoverable 24 0.0 2008.3–2013.75 -32 (0.014) -6.7 23.9

Zinc, filtered 54 0.0 2003.5–2013.75 -14 (0.328) -1.4 34.8

Zinc, unfiltered-recoverable 24 0.0 2008.3–2013.75 -41 (0.040) -9.3 42.2

Arsenic, filtered 54 0.0 2003.5–2013.75 36 (0.352) 3.1 88.3

Arsenic, unfiltered-recoverable 24 0.0 2008.3–2013.75 -49 (0.044) -12 55.5

Crystal Mine adit (site 6, fig. 1, table 1)

Specific conductance 46 0.0 2003.5–2013.75 -23 (<0.001) -2.5 12.3

Cadmium, filtered 47 0.0 2003.5–2013.75 -25 (<0.001) -2.8 13.6

Cadmium, unfiltered-recoverable 22 0.0 2008.3–2013.75 -1 (0.719) -0.6 13.1

Copper, filtered 47 0.0 2003.5–2013.75 19 (0.180) 1.7 26.4

Copper, unfiltered-recoverable 22 0.0 2008.3–2013.75 5 (0.374) 3.5 31.1

Lead, filtered 41 0.0 2003.5–2013.75 114 (0.007) 7.7 58.6

Lead, unfiltered-recoverable 22 0.0 2008.3–2013.75 29 (0.032) 19 66.9

Zinc, filtered 47 0.0 2003.5–2013.75 -16 (0.032) -1.6 15.6

Zinc, unfiltered-recoverable 22 0.0 2008.3–2013.75 -1 (0.538) -1.0 12.9

Arsenic, filtered 41 0.0 2003.5–2013.75 12 (0.704) 1.1 66.6

Arsenic, unfiltered-recoverable 22 0.0 2008.3–2013.75 13 (0.462) 9.0 114.0
Table 3–2. Detailed flow-adjusted water-quality trend results for the stream sites in the Boulder River and Tenmile Creek watersheds, Montana, based on 

analysis of data collected during water years 1997–2013.

[Water year is the 12-month period from October 1 through September 30 and is designated by the year in which it ends. Values in parentheses indicate p-values for associated percent change. 

Gray shading indicates statistical significance (p-value less than 0.01 for trends; p-value less than 0.05 for streamflow coefficient). p-value, statistical probability level; SEE, standard error of 

estimate; ND, not determined; <, less than]

Constituent or property Number of 

samples

Percent 

censored 

values

Trend-analysis period, 

decimal years

Trend, percent change 

in trend-analysis 

period

Trend, percent 

change per year

p-value for 

streamflow 

coefficient

SEE

Boulder River above Kleinsmith Gulch (site 1, fig. 1, table 1)

Specific conductance 40 0.0 1996.75–2013.75 -21 (0.010) -1.3 <0.001 15

Cadmium, filtered 39 92.5 ND1 ND1 ND1 ND1 ND1

Cadmium, unfiltered-recoverable 40 67.5 ND1 ND1 ND1 ND1 ND1

Copper, filtered 40 5.0 1996.75–2013.75 -33 (0.035) -2.3 0.024 34

Copper, unfiltered-recoverable 40 2.5 1996.75–2013.75 -42 (0.039) -3.2 0.005 48

Lead, filtered 40 57.5 ND1 ND1 ND1 ND1 ND1

Lead, unfiltered-recoverable 40 52.5 ND1 ND1 ND1 ND1 ND1

Zinc, filtered 40 5.0 1996.75–2013.75 -18 (0.485) -1.1 0.590 52

Zinc, unfiltered-recoverable 40 42.5 1996.75–2013.75 -44 (0.043) -3.4 0.074 47

Arsenic, filtered 40 0.0 1996.75–2013.75 -17 (0.029) -1.1 0.963 15

Arsenic, unfiltered-recoverable 39 0.0 1996.75–2013.75 -29 (0.047) -2.0 0.319 31

Suspended sediment 40 0.0 1996.75–2013.75 -23 (0.330) -1.6 <0.001 51

Bullion Mine tributary at mouth (site 3, fig. 1, table 1)

Specific conductance 69 0.0 1996.75–2013.75 -40 (<0.001) -2.9 <0.001 21

Cadmium, filtered 71 0.0 1996.75–2013.75 -76 (<0.001) -8.1 <0.001 33

Cadmium, unfiltered-recoverable 70 0.0 1996.75–2013.75 -76 (<0.001) -8.0 <0.001 32

Copper, filtered 71 0.0 1996.75–2013.75 -80 (<0.001) -9.1 <0.001 81

Copper, unfiltered-recoverable 70 0.0 1996.75–2013.75 -76 (<0.001) -8.2 <0.001 46

Lead, filtered 70 11.4 1996.75–2013.75 -59 (0.165) -5.1 0.987 250

Lead, unfiltered-recoverable 70 0.0 1996.75–2013.75 -83 (<0.001) -9.9 0.001 70

Zinc, filtered 71 0.0 1996.75–2013.75 -72 (<0.001) -7.3 <0.001 41

Zinc, unfiltered-recoverable 70 0.0 1996.75–2013.75 -74 (<0.001) -7.6 <0.001 36

Arsenic, filtered 71 5.6 1996.75–2013.75 78 (0.058) 3.5 <0.001 77

Arsenic, unfiltered-recoverable 71 0.0 1996.75–2013.75 -78 (<0.001) -8.5 <0.001 68

Suspended sediment 68 0.0 1996.75–2013.75 -67 (0.003) -6.3 0.014 99

Jack Creek at mouth (site 4, fig. 1, table 1)

Specific conductance 54 0.0 1996.75–2013.75 -4 (0.346) -0.3 <0.001 9.5

Cadmium, filtered 55 0.0 1996.75–2013.75 -58 (<0.001) -6.2 <0.001 28
Constituent or property Number of 

samples

Percent 

censored 

values

Trend-analysis period, 

decimal years

Trend, percent change 

in trend-analysis 

period

Trend, percent 

change per year

p-value for 

streamflow 

coefficient

SEE

Jack Creek at mouth (site 4, fig. 1, table 1)—Continued

Cadmium, unfiltered-recoverable 55 0.0 1996.75–2013.75 -62 (<0.001) -6.8 0.016 35

Copper, filtered 54 0.0 1996.75–2013.75 -58 (<0.001) -6.1 0.022 34

Copper, unfiltered-recoverable 55 0.0 1996.75–2013.75 -63 (<0.001) -6.9 0.034 54

Lead, filtered 54 7.4 1996.75–2013.75 -2 (0.903) -0.2 <0.001 40

Lead, unfiltered-recoverable 54 1.9 1996.75–2013.75 -64 (<0.001) -7.3 <0.001 60

Zinc, filtered 55 0.0 1996.75–2013.75 -46 (<0.001) -4.5 <0.001 28

Zinc, unfiltered-recoverable 55 0.0 1996.75–2013.75 -52 (<0.001) -5.3 0.001 32

Arsenic, filtered 55 0.0 1996.75–2013.75 -7 (0.496) -0.5 0.297 23

Arsenic, unfiltered-recoverable 54 0.0 1996.75–2013.75 -49 (0.001) -4.8 <0.001 45

Suspended sediment 55 0.0 1996.75–2013.75 -65 (0.006) -7.4 <0.001 100

Basin Creek at Basin (site 5, fig. 1, table 1)

Specific conductance 70 0.0 1996.75–2013.75 -5 (0.223) -0.3 <0.001 10

Cadmium, filtered 72 2.8 1996.75–2013.75 -49 (<0.001) -3.8 0.033 22

Cadmium, unfiltered-recoverable 72 22.2 1996.75–2013.75 -44 (<0.001) -3.3 <0.001 25

Copper, filtered 72 0.0 1996.75–2013.75 -32 (<0.001) -2.3 <0.001 24

Copper, unfiltered-recoverable 71 0.0 1996.75–2013.75 -35 (<0.001) -2.5 <0.001 27

Lead, filtered 72 27.8 1996.75–2013.75 2 (0.858) 0.1 <0.001 31

Lead, unfiltered-recoverable 72 16.7 1996.75–2013.75 -37 (0.062) -2.7 <0.001 60

Zinc, filtered 72 0.0 1996.75–2013.75 -38 (<0.001) -2.8 0.202 22

Zinc, unfiltered-recoverable 72 0.0 1996.75–2013.75 -44 (<0.001) -3.4 <0.001 22

Arsenic, filtered 72 0.0 1996.75–2013.75 -27 (<0.001) -1.8 0.088 16

Arsenic, unfiltered-recoverable 71 0.0 1996.75–2013.75 -42 (<0.001) -3.2 <0.001 35

Suspended sediment 72 0.0 1996.75–2013.75 -36 (0.057) -2.6 <0.001 67

Cataract Creek above Uncle Sam Gulch (site 7, fig. 1, table 1)

Specific conductance 44 0.0 1996.75–2013.75 -8 (0.068) -0.5 <0.001 9.9

Cadmium, filtered 44 13.6 1996.75–2013.75 -25 (0.021) -1.7 0.441 25

Cadmium, unfiltered-recoverable 44 22.7 1996.75–2013.75 -18 (0.206) -1.2 0.166 28

Table 3–2. Detailed flow-adjusted water-quality trend results for the stream sites in the Boulder River and Tenmile Creek watersheds, Montana, based on 

analysis of data collected during water years 1997–2013.—Continued

[Water year is the 12-month period from October 1 through September 30 and is designated by the year in which it ends. Values in parentheses indicate p-values for associated percent change. 

Gray shading indicates statistical significance (p-value less than 0.01 for trends; p-value less than 0.05 for streamflow coefficient). p-value, statistical probability level; SEE, standard error of 

estimate; ND, not determined; <, less than]
Constituent or property Number of 

samples

Percent 

censored 

values

Trend-analysis period, 

decimal years

Trend, percent change 

in trend-analysis 

period

Trend, percent 

change per year

p-value for 

streamflow 

coefficient

SEE

Cataract Creek above Uncle Sam Gulch (site 7, fig. 1, table 1)—Continued

Copper, filtered 44 0.0 1996.75–2013.75 -31 (<0.001) -2.2 0.004 15

Copper, unfiltered-recoverable 44 0.0 1996.75–2013.75 -29 (<0.001) -2.1 <0.001 16

Lead, filtered 44 29.5 1996.75–2013.75 -9 (0.601) -0.6 0.003 29

Lead, unfiltered-recoverable 44 22.7 1996.75–2013.75 -20 (0.420) -1.3 <0.001 50

Zinc, filtered 44 0.0 1996.75–2013.75 -15 (0.052) -1.0 0.843 19

Zinc, unfiltered-recoverable 46 0.0 1996.75–2013.75 -23 (0.001) -1.6 0.004 18

Arsenic, filtered 44 0.0 1996.75–2013.75 0 (0.965) -0.0 0.299 16

Arsenic, unfiltered-recoverable 44 0.0 1996.75–2013.75 2 (0.877) 0.1 0.016 24

Suspended sediment 43 0.0 1996.75–2013.75 -30 (0.241) -2.1 <0.001 75

Cataract Creek at Basin (site 8, fig. 1, table 1)

Specific conductance 70 0.0 1996.75–2013.75 0 (0.984) -0.0 <0.001 13

Cadmium, filtered 73 0.0 1996.75–2013.75 -71 (<0.001) -7.1 <0.001 25

Cadmium, unfiltered-recoverable 73 0.0 1996.75–2013.75 -71 (<0.001) -7.1 <0.001 28

Copper, filtered 73 0.0 1996.75–2013.75 -75 (<0.001) -7.8 <0.001 29

Copper, unfiltered-recoverable 73 0.0 1996.75–2013.75 -76 (<0.001) -8.0 <0.001 34

Lead, filtered 73 30.1 1996.75–2013.75 14 (0.509) 0.8 <0.001 44

Lead, unfiltered-recoverable 73 15.1 1996.75–2013.75 -6 (0.819) -0.3 <0.001 68

Zinc, filtered 73 0.0 1996.75–2013.75 -62 (<0.001) -5.5 <0.001 25

Zinc, unfiltered-recoverable 73 0.0 1996.75–2013.75 -66 (<0.001) -6.1 0.025 25

Arsenic, filtered 73 0.0 1996.75–2013.75 27 (0.001) 1.4 0.008 19

Arsenic, unfiltered-recoverable 72 0.0 1996.75–2013.75 -25 (0.052) -1.7 <0.001 41

Suspended sediment 72 0.0 1996.75–2013.75 -48 (0.014) -3.7 <0.001 76

High Ore Creek near Basin (site 9, fig. 1, table 1)

Specific conductance 43 0.0 1996.75–2013.75 -20 (<0.001) -1.3 <0.001 13

Cadmium, filtered 42 0.0 1996.75–2013.75 -57 (<0.001) -4.9 0.683 32

Cadmium, unfiltered-recoverable 43 0.0 1996.75–2013.75 -47 (<0.001) -3.6 <0.001 38

Copper, filtered 43 2.3 1996.75–2013.75 -54 (<0.001) -4.5 0.010 23

Table 3–2. Detailed flow-adjusted water-quality trend results for the stream sites in the Boulder River and Tenmile Creek watersheds, Montana, based on 

analysis of data collected during water years 1997–2013.—Continued

[Water year is the 12-month period from October 1 through September 30 and is designated by the year in which it ends. Values in parentheses indicate p-values for associated percent change. 

Gray shading indicates statistical significance (p-value less than 0.01 for trends; p-value less than 0.05 for streamflow coefficient). p-value, statistical probability level; SEE, standard error of 

estimate; ND, not determined; <, less than]
Constituent or property Number of 

samples

Percent 

censored 

values

Trend-analysis period, 

decimal years

Trend, percent change 

in trend-analysis 

period

Trend, percent 

change per year

p-value for 

streamflow 

coefficient

SEE

High Ore Creek near Basin (site 9, fig. 1, table 1)—Continued

Copper, unfiltered-recoverable 43 0.0 1996.75–2013.75 -40 (0.031) -3.0 <0.001 61

Lead, filtered 42 50.0 1996.75–2013.75 -18 (0.553) -1.2 0.002 80

Lead, unfiltered-recoverable 42 0.0 1996.75–2013.75 -36 (0.205) -2.6 <0.001 100

Zinc, filtered 43 0.0 1996.75–2013.75 -53 (<0.001) -4.4 0.011 38

Zinc, unfiltered-recoverable 43 0.0 1996.75–2013.75 -49 (<0.001) -3.9 <0.001 35

Arsenic, filtered 43 0.0 1996.75–2013.75 42 (0.002) 2.1 0.010 26

Arsenic, unfiltered-recoverable 42 0.0 1996.75–2013.75 -11 (0.635) -0.7 0.009 67

Suspended sediment 40 0.0 1996.75–2013.75 -18 (0.592) -1.2 <0.001 110

Boulder River below Little Galena Gulch (site 10, fig. 1, table 1)

Specific conductance 73 0.0 1996.75–2013.75 -1 (0.846) -0.1 <0.001 13

Cadmium, filtered 74 2.7 1996.75–2013.75 -60 (<0.001) -5.2 0.238 30

Cadmium, unfiltered-recoverable 74 21.6 1996.75–2013.75 -53 (<0.001) -4.3 0.003 48

Copper, filtered 74 0.0 1996.75–2013.75 -47 (<0.001) -3.6 0.039 19

Copper, unfiltered-recoverable 74 0.0 1996.75–2013.75 -44 (<0.001) -3.3 <0.001 43

Lead, filtered 74 31.1 1996.75–2013.75 42 (0.176) 2.1 <0.001 47

Lead, unfiltered-recoverable 74 12.2 1996.75–2013.75 -16 (0.497) -1.0 <0.001 72

Zinc, filtered 74 0.0 1996.75–2013.75 -55 (<0.001) -4.6 0.692 30

Zinc, unfiltered-recoverable 74 0.0 1996.75–2013.75 -53 (<0.001) -4.3 0.002 41

Arsenic, filtered 74 0.0 1996.75–2013.75 7 (0.353) 0.4 0.005 19

Arsenic, unfiltered-recoverable 73 0.0 1996.75–2013.75 -18 (0.257) -1.2 <0.001 50

Suspended sediment 74 0.0 1996.75–2013.75 -40 (0.041) -3.0 <0.001 73

Tenmile Creek above City Diversion (site 11, fig. 1, table 1)

Specific conductance 57 0.0 1996.75–2013.75 1 (0.867) 0.1 <0.001 14

Cadmium, filtered 57 5.3 1996.75–2013.75 -23 (0.070) -1.8 <0.001 30

Cadmium, unfiltered-recoverable 57 5.3 1996.75–2013.75 -21 (0.117) -1.6 0.002 32

Copper, filtered 56 0.0 1996.75–2013.75 -41 (<0.001) -3.6 <0.001 14

Copper, unfiltered-recoverable 57 0.0 1996.75–2013.75 -42 (<0.001) -3.7 <0.001 19

Table 3–2. Detailed flow-adjusted water-quality trend results for the stream sites in the Boulder River and Tenmile Creek watersheds, Montana, based on 

analysis of data collected during water years 1997–2013.—Continued

[Water year is the 12-month period from October 1 through September 30 and is designated by the year in which it ends. Values in parentheses indicate p-values for associated percent change. 

Gray shading indicates statistical significance (p-value less than 0.01 for trends; p-value less than 0.05 for streamflow coefficient). p-value, statistical probability level; SEE, standard error of 

estimate; ND, not determined; <, less than]
Constituent or property Number of 

samples

Percent 

censored 

values

Trend-analysis period, 

decimal years

Trend, percent change 

in trend-analysis 

period

Trend, percent 

change per year

p-value for 

streamflow 

coefficient

SEE

Tenmile Creek above City Diversion (site 11, fig. 1, table 1)—Continued

Lead, filtered 57 7.0 1996.75–2013.75 12 (0.548) 0.8 0.240 42

Lead, unfiltered-recoverable 57 0.0 1996.75–2013.75 -40 (0.023) -3.5 <0.001 52

Zinc, filtered 57 0.0 1996.75–2013.75 -2 (0.853) -0.2 <0.001 27

Zinc, unfiltered-recoverable 57 0.0 1996.75–2013.75 -11 (0.398) -0.8 <0.001 30

Arsenic, filtered 54 0.0 1996.75–2013.75 39 (0.001) 2.3 <0.001 20

Arsenic, unfiltered-recoverable 57 0.0 1996.75–2013.75 1 (0.951) 0.1 0.479 36

Suspended sediment 57 0.0 1996.75–2013.75 -29 (0.258) -2.4 <0.001 75

Minnehaha Creek near Rimini (site 12, fig. 1, table 1)

Specific conductance 64 0.0 1996.75–2013.75 -9 (0.005) -0.6 <0.001 7.9

Cadmium, filtered 61 0.0 1996.75–2013.75 -53 (<0.001) -4.5 <0.001 14

Cadmium, unfiltered-recoverable 61 0.0 1996.75–2013.75 -49 (<0.001) -4.0 0.233 15

Copper, filtered 63 0.0 1996.75–2013.75 -32 (<0.001) -2.4 <0.001 14

Copper, unfiltered-recoverable 65 0.0 1996.75–2013.75 -43 (<0.001) -3.4 <0.001 33

Lead, filtered 65 27.7 1996.75–2013.75 137 (<0.001) 5.4 <0.001 36

Lead, unfiltered-recoverable 63 17.5 1996.75–2013.75 20 (0.485) 1.1 <0.001 56

Zinc, filtered 65 0.0 1996.75–2013.75 -48 (<0.001) -3.9 <0.001 15

Zinc, unfiltered-recoverable 65 0.0 1996.75–2013.75 -52 (<0.001) -4.3 0.011 15

Arsenic, filtered 55 0.0 1996.75–2013.75 -3 (0.643) -0.2 0.270 16

Arsenic, unfiltered-recoverable 65 3.1 1996.75–2013.75 2 (0.780) 0.1 <0.001 21

Suspended sediment 64 0.0 1996.75–2013.75 -14 (0.572) -0.9 <0.001 73

Tenmile Creek near Rimini (site 13, fig. 1, table 1)

Specific conductance 33 0.0 1996.75–2013.75 0 (0.975) 0.0 <0.001 16

Cadmium, filtered 33 0.0 1996.75–2013.75 75 (0.049) 6.7 0.125 46

Cadmium, unfiltered-recoverable 33 0.0 1996.75–2013.75 60 (0.101) 5.7 0.523 48

Copper, filtered 33 0.0 1996.75–2013.75 20 (0.382) 2.1 <0.001 34

Copper, unfiltered-recoverable 33 0.0 1996.75–2013.75 18 (0.555) 1.9 <0.001 47

Lead, filtered 33 9.1 1996.75–2013.75 182 (0.003) 13 <0.001 56

Table 3–2. Detailed flow-adjusted water-quality trend results for the stream sites in the Boulder River and Tenmile Creek watersheds, Montana, based on 

analysis of data collected during water years 1997–2013.—Continued

[Water year is the 12-month period from October 1 through September 30 and is designated by the year in which it ends. Values in parentheses indicate p-values for associated percent change. 

Gray shading indicates statistical significance (p-value less than 0.01 for trends; p-value less than 0.05 for streamflow coefficient). p-value, statistical probability level; SEE, standard error of 

estimate; ND, not determined; <, less than]
Constituent or property Number of 

samples

Percent 

censored 

values

Trend-analysis period, 

decimal years

Trend, percent change 

in trend-analysis 

period

Trend, percent 

change per year

p-value for 

streamflow 

coefficient

SEE

Tenmile Creek near Rimini (site 13, fig. 1, table 1)—Continued

Lead, unfiltered-recoverable 33 0.0 1996.75–2013.75 79 (0.145) 7.1 <0.001 70

Zinc, filtered 33 0.0 1996.75–2013.75 83 (0.025) 7.3 0.012 43

Zinc, unfiltered-recoverable 33 0.0 1996.75–2013.75 67 (0.056) 6.1 0.334 43

Arsenic, filtered 33 0.0 1996.75–2013.75 12 (0.602) 1.3 <0.001 35

Arsenic, unfiltered-recoverable 33 0.0 1996.75–2013.75 -3 (0.946) -0.3 0.543 70

Suspended sediment 32 0.0 1996.75–2013.75 -70 (0.044) -13 <0.001 120

1

Not determined because of an excessive number of censored values (that is, greater than 50 percent of values were reported as less than the laboratory reporting level).

Table 3–2. Detailed flow-adjusted water-quality trend results for the stream sites in the Boulder River and Tenmile Creek watersheds, Montana, based on 

analysis of data collected during water years 1997–2013.—Continued

[Water year is the 12-month period from October 1 through September 30 and is designated by the year in which it ends. Values in parentheses indicate p-values for associated percent change. 

Gray shading indicates statistical significance (p-value less than 0.01 for trends; p-value less than 0.05 for streamflow coefficient). p-value, statistical probability level; SEE, standard error of 

estimate; ND, not determined; <, less than]