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Feb 22, 2014 (3 years and 5 months ago)

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Module 10/11

Stream Surveys

Stream Surveys


February 2004

Part 1


Water Quality Assessment

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Objectives

Students will be able to:


describe techniques used to determine dissolved oxygen.


list factors that influence high turbidity and suspended
solids in streams.


explain methods used to determine total suspended solids.


evaluate the relationship between total suspended solids
and turbidity.


identify methods used to determine water clarity in streams.


assess habitat degradation by determining the degree of
sediment embeddedness in a stream.


analyze the impact of dissolved salts, pH and temperature
on streams.


describe accepted sampling methods used in stream
surveys.

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Stream assessments


Water quality


Habitat


Hydrologic


Biological


Watershed

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Water quality parameters

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Water Quality Parameters


Dissolved oxygen


Suspended sediments (TSS) and turbidity


Specific conductivity (EC)


alkalinity


pH


Temperature


Major ions



All of these parameters are presented in
greater detail in Module 9


Lake surveys

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Dissolved Oxygen

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DO


importance and reporting


Oxygen is produced during photosynthesis
and consumed during respiration and
decomposition
.


Generally < 3 mg/L is stressful to aquatic life
.


Units of measurement are
:


Concentration: mg/L = ppm; concentrations range 0.0 to
20 mg/L


% saturation


used to determine if water is fully
saturated with oxygen at a particular temperature

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DO


techniques


Probe types and measurement techniques
:


Winkler titration


Amperometric (polarographic) method, most
commonly used


http://www.lumcon.edu/education/StudentDatabase/gallery.asp


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DO


probes


Most common sensor is the temperature
compensated polarographic membrane
-
type
(amperometric)


Temperature sensitive (but virtually all are
compensated).


The probes actually consume O
2

as they work so
measurements require moving water using either
a built
-
in stirrer (typical in multiparameter sondes
and BOD probes) or “
hand jiggling”
during the
measurement.


in situ

sensors are prone to fouling by
algal/bacterial slimes and by silt in streams.

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DO probes and meters


The WOW units use either Hydrolab or YSI
multiprobe datasounds, but there are many others

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Sedimentation/siltation


Excessive sedimentation in streams and rivers is
considered to be a major cause of surface water
pollution in the U.S. by the USEPA

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Measures of sedimentation


Suspended sediments



Turbidity



Embededdness

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High turbidity and suspended solids


Caused by many factors including:


soil erosion


domestic and industrial wastewater discharge


urban runoff


flooding


algal growth due to nutrient enrichment


dredging operations


channelization


removal of riparian vegetation and other stream
bank disturbances

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Total suspended solids and turbidity


Both are indicators of the amount of solids
suspended in the water


Mineral (e.g., soil particles)


Organic (e.g., algae, detritus)


TSS measures the actual weight of material per
volume of water (mg/L)


Turbidity measures the amount of light
scattered


Therefore, TSS allows the determination of an
actual concentration or quantity of material
while turbidity does not

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Measuring TSS

1.
Filter a known amount of
water through a pre
-
washed,
pre
-
dried at 103
-
105
o
C, pre
-
weighed (~
+

0.5 mg) filter

2.
Rinse, dry and reweigh to
calculate TSS in mg/L (ppm)


3.
Save filters for other analyses
such as volatile suspended
solids (VSS) that estimate
organic matter


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Total suspended solids
-

method

What type of
filter to use?

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Calculate TSS by using the equation below


TSS (mg/L) = ([A
-
B]*1000)/C


where


A = final dried weight of the filter (in milligrams = mg)


B = Initial weight of the filter (in milligrams = mg)


C = Volume of water filtered (in Liters)



Total suspended solids

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TSS


Range of results and what the results mean


Example:


Suspended solids concentrations at Slate Creek
WA average 150.8 mg/l with a range of 50 to 327
mg/l. It is generally desired to maintain total
suspended solid concentrations below 100 mg/l.



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Turbidity measures the
scattering effect
suspended particles have
on light


inorganics like clay and silt


organic material, both fine
and colored


plankton and other
microscopic organisms


Transparency or turbidity
tubes



Even small amounts of wave action can
erode exposed lakeshore sediments, in
this case a minepit lake from northeastern
Minnesota. Guess the mineral mined here.

Measuring turbidity

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Turbidity


Field turbidity measurements are made with


Turbidimeters (bench meter for discrete samples)


Submersible turbidity sensors (Note
-

USGS
currently considers this a
qualitative

method)


Hydrolab turbidity probe

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Turbidity
-

Nephelometric optics


Nephelometric turbidity estimated by the
scattering effect suspended particles have on
light


Detector is at 90
o

from the light source


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Turbidity


units and reporting


Nephelometric Turbidity Units (NTU) standards
are formazin or other certified material



JTU’s are from an “older” technology in which
a candle flame was viewed through a tube of
water



1 NTU = 1 JTU (Jackson Turbidity Unit)



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Turbidity
-

standards


Top
-

a range of
formazin standards


Bottom

the same
NTU range using a
clay suspension

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Turbidity


Range of results and what the results mean


Ex: Salmon Creek Watershed (OR/WA border)
TMDL for turbidity is:

"Turbidity shall not exceed 5 NTU over
background turbidity when the background
turbidity is 50 NTU or less. Or more than a 10%
increase in turbidity when the background
turbidity is > 50 NTU”.

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How do turbidity and TSS relate?

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TSS vs Turbidity relationship

TSS

Turbidity

Yearly

average

Summer range
(May
-
Oct)

Winter range
(Nov
-
Apr)

Cedar River

3.6

1.1

0.6
-
5.0

0.4
-
1.2

3.5
-
6.2

1.0
-
2.0

Newaukum Ck

5.7

2.4

1.6
-
5.1

0.7
-
1.5

7.5
-
8.8

3.1
-
4.0

Springbrook Ck

19.8

22.0

8.0
-
26.0

13.0
-
44.0

6.7
-
44.0

13.0
-
35.0

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Water clarity


transparency tubes

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Water clarity


transparency tubes


Used in streams, ponds,
wetlands, and some
coastal zones


Analogous to secchi
depth in lakes: a measure
of the dissolved and
particulate material in the
water


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Water clarity


transparency tubes


Useful for shallow water or fast
moving streams bodies where
a secchi would still be visible
on the bottom


It is a good measure of
turbidity and suspended
sediment (TSS)


Used in many volunteer
stream monitoring programs


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Horizontal secchi


Newer method


all
-
black disk viewed
horizontally


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Embeddedness


Measure of fine sediment deposition in the
interstitial spaces between rocks


High embeddedness values indicate habitat
degradation


Visual assessment used to estimate the
degree of embeddedness

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Embeddedness


cont.


The stream
-
bottom
sediments to the top right
provide spaces for fish to
lay eggs and for
invertebrates to live and
hide.


Excess erosion has
deposited fine grained
sediments on the stream
bottom to the bottom right.
There are no spaces
available for fish spawning
or for invertebrate habitat.

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Embededdness


visual assessment


Embeddedness: General guidelines


0% = no fine sediments even at base of top
layer of gravel/cobble


25% = rocks are half surrounded by sediment


50% = rocks are completely surrounded by
sediment but their tops are clean


75% = rocks are completely surrounded by
sediment and half covered


100% = rocks are completely covered by
sediment

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Specific electrical conductivity = EC25

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EC25
-

importance


Cheap, easy way to characterize the total
dissolved salt concentration of a water sample



For tracing water masses and defining mixing
zones



Groundwater plumes


Stream flowing into another stream or into a lake or
reservoir


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EC25


units and reporting

Principle of measurement



A small voltage is applied between 2 parallel
metal rod shaped electrodes, usually 1 cm apart



Measured current flow is proportional to the
dissolved ion content of the water



If the sensor is temperature compensated to
25
o
C, EC is called
“specific”

EC (EC25)


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EC25
-

units


What in the world are

microSiemens per centimeter (µS/cm)?



Units for EC and EC25 are mS/cm or
μS/cm
@25
o
C. The WOW site reports it as EC @25
o
C (in
μS/cm)
.



Usually report to 2 or 3 significant figures (to
+

~ 1
-
5
μS/cm)


More details can be found in Module 9

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EC25


EC25 values in streams reflect primarily a combination
of watershed sources of salts and the hydrology of the
system


wastewater

from sewage treatment plants and
industrial discharge


wastewater
from on
-
site wastewater treatment and
dispersal systems (septic systems and drainfields)


urban runoff



agricultural runoff



acid mine drainage



atmospheric inputs


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Snowmelt runoff example

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pH

Image courtesy of USGS at http://www.usgs.gov/

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pH


importance in aquatic systems


The pH of a sample of water is a measure of the
concentration of hydrogen ions.



pH determines the solubility and biological
availability of chemical constituents such as
nutrients (phosphorus, nitrogen, and carbon)
and heavy metals (lead, copper, cadmium, etc.).



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pH
-

reporting


pH can be measured electrometrically or
colorimetrically (pH paper) BUT
ONLY

the
former technique is approved by the EPA and
USGS for natural waters.


The electrometric method uses a hydrogen ion
electrode.


pH meters require extensive care in handling
and operation.


Report to the nearest 0.1 standard pH unit

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pH


probes


Field probe types
:


Combination probes (e.g.YSI)


Less expensive; more rugged design


Less precise


Shorter life because reference solution cannot be
replenished


Separate reading and reference electrodes (e.g.,
Hydrolab)


Costs more


More precise; faster response time


Allows user maintenance; Teflon junction and electrolyte
can be replaced

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pH


probes


Or, alternatively, a bench or hand
-
held meter
and probe can be used in a fresh subsample if
you don’t have a field meter with a pH probe
.


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Temperature

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Temperature importance


Temperature affects:



the oxygen content of the water (oxygen levels
become lower as temperature increases)


the rate of photosynthesis by aquatic plants


the metabolic rates of aquatic organisms


the sensitivity of organisms to toxic wastes,
parasites, and diseases

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Temperature measurement
-

probes


Types of probes


Liquid
-
in
-
glass


Thermistor: based on measuring changes in electrical
resistance of a semi
-
conductor with increasing
temperature.


thermistor on a YSI sonde

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Temperature changes


Causes of temperature change include:


weather


removal of shading streambank vegetation,



impoundments (a body of water confined by a
barrier, such as a dam)


discharge of cooling water


urban storm water


groundwater inflows to the stream


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Temperature changes
-

continued

Graph showing
factors that
influence
stream
temperature,
from Bartholow
(1989).

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Temperature criteria


example

Here’s an example of a temperature TMDL for a California
stream

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Temperature criteria


cont.

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Temperature


summer rain storm

Summer rainfall event

Bump in stream temp (and
turbidity)

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Other Water Quality Parameters


Nutrients


nitrogen and phosphorus


Fecal coliforms


Biochemical oxygen demand (BOD)


Metals


Toxic contaminants


Details on analyzing these parameters are in
Module 9


Lake Surveys

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Fecal coliforms


Pathogens are number one

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Water sampling
-

microbes


Sterile technique:


Containers must be
sterilized by autoclaving
or with gas used to kill
microbes


Take care not to
contaminate the
container


Water samplers should
be swabbed with 70 %
alcohol

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Bacteria


E. coli

and fecal coliforms


Fecal bacteria are used as indicators of
possible sewage contamination



These bacteria indicate the possible presence
of disease
-
causing bacteria, viruses, and
protozoans that also live in human and animal
digestive systems



E. coli

is currently replacing the fecal coliform
assay in most beach monitoring programs

See Module 9 for a detailed discussion of
measuring pathogens

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Water sample collection


grab samples

Grab samples for fecal
coliforms are taken with
sterile containers

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Water sample collection


A detailed discussion on how to manually collect stream
and river water can be found in the USGS Field Manual
Chapter 4: Collection of Water Samples



General considerations:


Sample in the main
current


Avoid disturbing bottom
sediments


Collect the water sample
on your upstream side



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Analyte

Volume needed

chlorophyll

>500 mLs

TSS

Often > 1 L

total phosphorus

total nitrogen

anions

200 to 500 mLs

Dissolved nutrients

~ 100mLs

Total and dissolved carbon

~60 mLs

Metals

~60 mLs


color, DOC

~60 mLs

Suggested sample volumes

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Stream sampling


sample labeling


An unlabeled sample
may as well just be
dumped down the
drain.



Use good labels not
masking tape, etc.
Poor labels often fall
off when frozen
samples are thawed.


Use permanent
markers
NOT

ball
point pens, pencils in
a pinch


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A simple sample label with the minimum amount of
information needed…


WOW

Tischer Creek 7/26/02

Reach 3

RAW, frozen

Lake sampling


sample labeling

Often, much more information may be needed by the laboratory
performing your analyses. You will also need to supply a chain of
custody form.

Stream sampling


sample labeling



project


Site,
date,
location

Sample processing and
preservation info

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Automated stream monitoring

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Water sampling
-

automated


Automated stream
sampling stations
provide continuous
monitoring of a variety of
parameters


These units are capable
of both collecting water
samples and measure
various water quality
parameters

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Automated stream samplers


Flow weighted composites


Flow weighted discrete


Sampling triggered by predetermined set point
such as:


Flow


Precipitation


Any other parameter measured by in
-
stream
sensors

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Automated sampling


Duluth Streams


These stream monitoring units are not “state of the art”
but provide near real
-
time data for delivery into the data
visualization tools