Downstream Effects of Glaciers on Stream Water Quality,
Mt. Hood, Oregon and Mt. Rainier, Washington
JANICE A. DOUGALL, DR. ANDREW G. FOUNTAIN
Department of Geography, Portland State University, Portland, Oregon,
Oregon, 97207 …………
Methods
Electrical Conductivity
Field data Measure temperature, turbidity, electrical conductivity, and collect suspended sediment, and
ion samples during late-summer on cloud-free days.
• Data loggers recorded temperature every 15 minutes over a period of days.
• Teams of 3 or 4 people measured conductivity and turbidity and sampled for suspended sediments
hourly for between 6 and 24 hours
• Samples were collected along streams in a Lagrangian fashion and included suspended sediment and
ionic concentration and testing for temperature, turbidity, electrical conductivity.
Statistical Analysis
1. To determine whether stream distance normalized by glacier size, L*, can be used to describe the
decay of water quality variables with distance from glaciers. To test L* we ran least squares
regressions of water quality variables over L*, and compared the results to regressions against stream
length, and basins’ fractional glacier coverage.
2. The non-parametric Mann-Whitney U test was applied to determine the stream distance to which
glacial streams differ significantly from non-glacial streams. Data were ordered from least to greatest L*
value, then water quality values were compared in blocks beginning with the greatest L* value, and
including those for smaller and smaller L* values until the sets were significantly different (p>0.05). This
was repeated beginning with L*<100, L*<50 and L*<25 in order to find the range of L* values at which
water quality variables became indistinguishable from non-glacial water.
Electrical conductivity (specific conductance) is low in both glacial and non-glacial headwaters, and
increases with distance, but varies by stream. The lowest measures of specific conductance were found
among glacial streams. Runoff from the two smallest glaciers studied, Palmer and White rivers, had the
lowest conductivities observed (<10μS cm-1). Runoff from larger glaciers, Emmons and Eliot, had
specific conductance values >20μS cm-1 close to the glaciers.
Electrical conductivity remained low in Palmer runoff, the Salmon River, to great distances, while some
non-glacial streams in agricultural settings had much higher conductivity.
Specific Conductance vs L*
Specific Conductance vs L*
Specific Conductance vs L*
Specific Conductance vs L*
120
120
160
160
140
140
White_Rainier
White_Rainier
Nisqually_R
Nisqually_R
Eliot/Hood_Hood
Eliot/Hood_Hood
White_Hood
White_Hood
Palmer/Salmon_Hood
Palmer/Salmon_Hood
All but Sandy
All but Sandy
Non-Glacial*
Non-Glacial*
Log. (All but Sandy)
Log. (All but Sandy)
Log. (Non-Glacial*)
Log. (Non-Glacial*)
120
120
100
100
80
80
60
60
40
40
20
20
0
0
0
100
100
Specific Conductance (uS/cm)
Specific Conductance (uS/cm)
Previous studies have shown that basins with partial glacier cover have less summer discharge variability
than non glacial basins due to increased melt during otherwise warm, dry periods ( e.g. Fountain and
Walder 1998). Other studies addressed glacier effects on water quality in the proglacial plain (e.g.
Gurnell 1982, Uehlinger et al. 2003). However, few studies consider distant downstream effects of
glaciers on water quality. Glacial meltwater is characterized by low temperatures, low concentrations of
soluble ions, high suspended sediment concentrations, and high turbidity (Milner and Petts 1994).These
qualities differ significantly between glacial and non-glacial streams. I hypothesize that the rate of change
of these variables with distance from the glacier will scale with fraction of glacier cover relative to
watershed area. As glaciers recede, the reach and magnitude of these characteristics will also shrink.
Specific Conductance (uS/cm)
Specific Conductance (uS/cm)
Introduction
60
60
40
40
20
20
0
20
20
0
40
40
60
60
80
80
White_Rainier
White_Rainier
Nisqually_R
Nisqually_R
Eliot/Hood_Hood
Eliot/Hood_Hood
White_Hood
White_Hood
Palmer/Salmon_Hood
Palmer/Salmon_Hood
All but Sandy
All but Sandy
Non-Glacial*
Non-Glacial*
Log. (Non-Glacial*)
Log. (Non-Glacial*)
Log. (All but Sandy)
Log. (All but Sandy)
80
80
0
0
100
100
0
2
2
4
Results
25
25
L*
Stream
Length
10
10
fractional glacier
cover
Temperature (Log)
0.8227
0.7739
0.8461
Suspended sediment
concentration (Power)
0.2104
0.4037
0.4063
Specific conductance
(Log)
0.4143
0.3937
0.5174
5
0
5
0
0
0
10
20
30
40
10
20
30
40
8
10
10
Clear SSC differences exist between glacial and non-glacial
streams, and between different glacial streams (see photo).
Glacial streams generally exhibit high SSC, especially close
to the glacier, and non-glacial streams tend to have low
concentrations. After about L*40, some glacial streams
sediment has settled out and some non-glacial streams have
gained particulates so that SSC is about the same.
50
60
70
80
90
100
50
60
70
80
90
100
L*
L*
Suspended Sediment Concentration v L*, semi-Log
Suspended Sediment Concentration v L*, semi-Log
10.0000
10.0000
1.0000
1.0000
0
0.4063
0.4126
10
10
0
20
20
White_R
White_R
Nisq_R
Nisq_R
Eliot_H
Eliot_H
Sandy_H
Sandy_H
White_H
White_H
Palmer
Palmer
All Glacial
All Glacial
Log. (All Glacial)
Log. (All Glacial)
Power (All Glacial)
Power (All Glacial)
30
30
0.1000
0.1000
0.0100
0.0100
Suspended Sediment Concentration v L*, semi-Log
Suspended Sediment Concentration v L*, semi-Log
10.0000
10.0000
0.0010
0.0010
L*
L*
1.0000
1.0000
0
Specific Conductance v L*
Specific Conductance v L*
300
300
Specific Conductance (uS/cm)
Specific Conductance (uS/cm)
Average temperature values were used. Median
suspended sediment concentration and specific
conductance were used because of the smaller
sample sizes. Sandy River conductivity was not
included in regressions, due to its anomalous
behavior. Correlation between L* and fractional
glacier cover and water quality characteristics
are stronger than stream length and water
quality characteristics.
250
250
White_R
White_R
Nisqually_R
Nisqually_R
Eliot/Hood_H
Eliot/Hood_H
Sandy_H
Sandy_H
White_H
White_H
Palmer/Salmon_H
Palmer/Salmon_H
All but Sandy
All but Sandy
Log. (All but Sandy)
Log. (All but Sandy)
200
200
150
150
100
100
50
50
0
0
0
SSC (mg/L)
SSC (mg/L)
0.2828
SSC (mg/L)
SSC (mg/L)
Specific conductance
(Power)
Tualatin River, (Non-Glacial)
8
Suspended Sediment Concentration (SSC)
White_R
White_R
Nisqually_R
Nisqually_R
Santiam_J
Santiam_J
Eliot/Hood_H
Eliot/Hood_H
Sandy_H
Sandy_H
White_H
White_H
Palmer/Salmon_H
Palmer/Salmon_H
All Glacial
All Glacial
Log. (All Glacial)
Log. (All Glacial)
20
20
15
15
R2 values for regressions on glacial data
Mt. Hood
Eliot Cr., Hood River (Eliot Glacier)
White River (White River Glacier)
Salmon River (Palmer Glacier)
Sandy River (Sandy Glacier)
6
Average Stream Temperature
Average Stream Temperature
compared with L*
compared with L*
Stream Distance Normalized by Glacier Area
Temperature (°C)
Temperature (°C)
Mt. Rainier
White River (Emmons Glacier)
Nisqually River (Nisqually Glacier)
6
4
L*
L*
L*
L*
0
10
10
20
20
30
30
L*
L*
40
40
50
50
0
20
20
40
40
60
60
80
80
0.1000
0.1000
0.0100
0.0100
0.0010
0.0010
White_R
White_R
Nisq_R
Nisq_R
Eliot_H
Eliot_H
Sandy_H
Sandy_H
White_H
White_H
Palmer
Palmer
Non-Glacial
Non-Glacial
All Glacial
All Glacial
Log. (All Glacial)
Log. (All Glacial)
Power (All Glacial)
Power (All Glacial)
0.0001
0.0001
60
60
L*
L*
Conclusions
Distances to which glacial water quality parameters persist
Little N. Santiam River, (Non-Glacial)
North Santiam R.,
(one sample, Mt. Jefferson glaciers)
Possible Limits on D ownstream Effects
Glacier Area
W hite_R
Nisqually_R
Eliot/Hood_H
0.4
Sandy_H
W hite_H
0.3
Palmer/Salmon_H
0.2
0.1
20
20
Temperature (°C)
Temperature (°C)
Stream Length
Glacial Rivers
Glacial Rivers
White_R
White_R
Nisqually_R
Nisqually_R
Santiam_J
Santiam_J
Eliot/Hood_H
Eliot/Hood_H
Sandy_H
Sandy_H
White_H
White_H
Palmer/Salmon_H
Palmer/Salmon_H
Non-Glacial
Non-Glacial
Log. (Glacial Rivers)
Log. (Glacial Rivers)
Log. (Non-Glacial)
Log. (Non-Glacial)
0.6
0.5
15
15
10
10
5
5
0
0
10
20
30
L*
40
50
60
0
0
0
0
10
10
20
20
L*
L*
30
30
Suspended sediment concentration appeared to depend more on factors other than glacier size.
Glacial water quality characteristics vary in magnitude along a stream according to glacier size, as can
be seen when temperature is plotted over stream distance and as conductivity at the glacier terminus
increases with size. Glacial stream temperatures are significantly different from non-glacial to at least 912 glacial lengths as measured by L*, and probably to at least 20 glacial lengths.
As glaciers shrink, the extent to which glacial water quality characteristics persist will likely shrink, too.
Average Glacial Stream Temperature
Average Glacial Stream Temperature
compared with Stream Distance
compared with Stream Distance
25
25
0.7
Fractional Glacier Cover
L* =
Average Stream Temperature
Average Stream Temperature
compared with L*
compared with L*
0.8
40
40
References
Fountain, A. G. Walder, J. S. 1998. Water flow through temperate glaciers, Reviews of Geophysics, 36: 299-328.
16
16
Gurnell, A.M. 1982. The dynamics of suspended sediment concentration in an Alpine pro-glacial stream network, Hydrological Aspects of Alpine and High Mountain Areas (Proceedings
of the Exeter Symposium, July, 1982). International Association of Hydrological Sciences, Publication No. 138.
14
14
12
12
Temperature (°C)
Temperature (°C)
Study Goals
Test whether stream distance normalized by glacier area,
L*, provides a useful measure of stream length for the
purpose of studying the variation of glacial stream water
quality.
Results indicate that L* is a useful indicator of water quality trends with distance from a glacier. While
fractional glacier cover (instead of L*) provides marginally better correlation, it is not as useful because it
does not explicitly account for stream distance.
Temperature
Visual inspection of a graph of glacial and non-glacial temperatures
shows that temperatures are distinctly different from non-glacial
streams to about 20 glacier lengths (L*). An analysis using MannWhiney U test of the difference of medians revealed statistical
differences between glacial and non-glacial temperatures to between
9L* and 12L*, but these included all temperatures beginning with L*0.
When listed by glacier size, water from larger glaciers stays colder
longer.
White_R
White_R
Nisqually_R
Nisqually_R
Eliot_H
Eliot_H
Sandy_H
Sandy_H
White_H
White_H
Palmer_H
Palmer_H
10
10
8
6
4
2
0
8
6
4
2
0
0
0
5
5
10
10
15
20
25
15
20
25
Stream Distance (km)
Stream Distance (km)
L* for non-glacial streams is calculated using a source area equivalent to the median Mt. Hood glacier size in the study.
30
30
35
35
40
40
Milner, A. M., Petts, G. E. 1994. Glacial rivers: physical habitat and ecology, Freshwater Biology, vol. 32: pp. 295-307.
Uehlinger, U., Malard, F., Ward, J.V. 2003. Thermal patterns in the surface waters of a glacial river corridor (Val Roseg, Switzerland), Freshwater Biology, vol. 48, pp: 284-300.
Acknowledgments:
City of Portland Bureau of Water Works, Stephen R. Hinkle of the USGS, Barbara Samora of Mount Rainier National Park, Yangdong Pan of the PSU Department of Environmental
Science and Resources, and Frank D. Granshaw/Artemis Science for the use of equipment, and Thomas Nylen and Keith Jackson for glacier shapefiles
Christine Weilhofer (PSU ESR) and Ben Perkins (PSU Geology) and Jean Jacoby (Seattle University) for help with analyses.
Field Assistants Michele Newell (x3!), Ben Brady, Marius Dogar, April Fong, David Graves, Norm Goldstein, Joe Hoopes, Jean Jacoby, Alex Levell, Joy Michaud, Jon Norred, and Azda
NASA-NNGO4GJ41G, and USGS Mountain Climate Initiative for funding