day was held for Mt Roland Rivercare Catchment Inc. committee members
and water monitors to trial water monitoring equipment and learn
the art and science of collecting water samples.
- How to
use the sample pole.
considerations on water monitoring.
notes and pictures from the day.
provided by Patricia Ellison, from North West Water Watch.
a water sample
to take a sample with the sampling pole
Try to get
a sample from the main flow of water and not the edges or where
water is held in pools, where there is likely to be more variation
from the main body of the river. Unless there is a specific reason
to sample water from a different location, the running water in
the centre of the river gives the best overall sample.
It is important
not to disturb the area that you are going to sample. Stand downstream
of where you will take the sample.
How to sample:
The pole is
extendable to approx. 2.5 metres. The sample bottle clips into place
at the end of the pole. Having more than one bottle available will
be helpful, if samples have to be taken away.
Rinse the bottle
a few times from water in the river before taking the sample and
avoid touching the rim of the bottle to avoid contamination of the
sample from anything on the hands.
Place the bottle
inverted in the body of water and turn it to the horizontal, facing
into the flow of water. It is recommended that the bottle be 10-20cm
below the surface of the water (depending upon the depth of water
at the sampling point).
For badly polluted
water, it is a good idea to use rubber/disposable gloves (from a
health and safety point of view) if there is any concern over the
temperature, place the probe directly in the main flow of water
- only the metal probe (and not the plastic handle) should be submerged.
It is also possible to take the temperature measurement from the
sample bottle of water instead. However, it is important to do this
as soon as the water sample has been obtained.
20 deg C is
considered to be the upper desirable limit for water temperature,
however the temperature range will vary according to a number of
factors - shading, time of day, season, locality, etc.
One of the
reasons for monitoring water temperature is because of the sensitivity
of living creatures in the river system to changing temperature.
Generally, they have adapted to a particular range and if the temperature
varies greatly from this, such as several days at higher than normal
temperatures, then it puts additional stress on them and their eco-system.
For example, willow removal has the potential to increase the water
temperature dramatically in an area and thus monitoring is important
to assess impact on that locality's eco-system.
This is a measure
of the amount of sediment in the water. This may be a problem at
certain times of the year, such as after heavy rainfalls or during
flooding, where soil is washed into the river system. Fine layers
of sediment are deposited as a result which may affect macro-invertebrates
living on the bottom of the river. As these are towards the bottom
of the food chain, whatever affects them can also have an affect
on those creatures that live off of them.
This is in
2 pieces which slot together - make sure that all the figures on
the side are in line before starting - and at the bottom of the
tube are a series of wiggly lines.
the turbidity of a particular sample of water, pour in water from
the sample until the wiggly lines are only just visible when viewed
from the top of the tube, looking down through the volume of water.
on the side represents nephelometric turbidity units or NTU's, with
a scale from 400 at the bottom of the tube to 7 at the very top.
25 NTU's is considered a reasonable standard - anything greater
than that indicates a problem. The relationship between NTU and
the depth of tube is an exponential curve (not linear) and this
needs to be considered when estimating readings in between the marked
where the water is extremely murky (in the 200-400 NTU range) then
the sample can be diluted to help in reading the gauge (the reading
would have to be adjusted for the dilution afterwards).
any staining of the water such as due to tannins, does not affect
the turbidity measurement.
It is important
to keep the tube clean (can use a bottle brush) as it relies on
light entering the tube through the sides to enable correct readings
to be taken.
meter measures electrical current between 2 electrodes and is therefore
a measure of the salinity of the water. This measure can be useful
for indicating if a problem exists upstream, by monitoring for any
is variable with temperature and the meter therefore has an in-built
calibration to adjust the reading for a temperature of 25 deg C.
Conductivity is also usually higher with lower water flows.
is measured in micro Siemens per centimetre ( S/cm) - 350 S/cm is
considered to be an upper limit for acceptability. For the rivers
in our catchment (ie Dasher, Minnow and Upper Don) an expected normal
range would be 80-130 S/cm.
How to measure
The meter can
be placed directly into the main flow of the creek or river if it
can be easily accessed, otherwise it can be used in the sample bottle.
The meter automatically
takes the temperature of the water at the same time in order to
compensate for and adjust to 25 deg C. It is important therefore
to allow sufficient time for the meter to adjust to the temperature
of the river (can be a minute or more especially if it has previously
been in the sun or a warm car). Press the HOLD button when you are
ready to take a reading, then the meter can then be removed from
the water and read.
of the probe should be kept clean and rinsed with distilled water.
Do not touch, wipe clean on clothing or anything similar as this
can contaminate and therefore invalidate the reading.
The meter should
be checked and re-calibrated at periodic intervals (3 to 6 months)
from a solution of known conductivity. Calibration is via 2 buttons
inside the top cover.
Ph can vary
according to the geology and catchment. Typically a PH between 6.5
and 7.5 is considered a normal range, however in Tasmania in upper
catchment areas this may often be higher.
PH can be an
indicator of higher nutrient levels (possibly caused by excessive
fertiliser use or leaking septic tanks).
PH is often
at the lowest during the morning and increases during the day. The
daily cycle of vegetation, in particular of photosynthesis is one
reason for this.
How to measure
A syringe may
be helpful to aid in filling the testing tube from water in the
sample bottle, both of which should be rinsed out a few times before
the reading is taken.
A length of
the test paper is inserted in the tube, sufficiently long to fill
the length of the tube, leaving the portion touched by the hand
outside of the tube. It is important not to handle the paper that
is being used for testing PH as contamination of the sample can
occur. Nor should the finger be used as a stopper for the same reason.
Pour in the
water after the paper is in place and replace the stopper. Place
the test tube on the PH chart along the black line and wait for
1 to 5 minutes before reading the nearest PH value. If the colour
appears to be within 2 values, then take the higher value (comparisons
done by NW Water Watch have indicated that the readings on this
scale are slightly on the low side).
Considerations On Water Monitoring
water quality within Australia have been set but are very general
and can vary according to many factors such as geology and the location.
It is very difficult to identify what is considered to be "right"
for one particular water system. To set a standard, would need a
minimum of 24 readings over a minimum period of 2 years.
chosen for water monitoring need careful consideration as geology
and land use play a large part in this equation. For example, while
there is ongoing river care work being done - such as willow removal
- this will effect change on the water quality and therefore introduce
variability in measurements taken to establish a "standard".
One option would be to include water monitoring of a near pristine
stretch of river to establish a consistent benchmark against which
other monitoring could be measured.
recording sheet will assist in proper record keeping and ensure
that all relevant data is collected together in a consistent format.
Time of day
is important to the water monitoring - measurements should be taken
at the same time of day. If temperature was a particular priority
for a series of measurements, then sampling at the hottest part
of the day would give the best indication of temperature related
measurements, if any reading is well outside of the expected range,
then the sampling should be repeated again and even with different
equipment, to ensure that there is no error in either the procedure
or the equipment.
As well as
a regular schedule of monitoring, it would be beneficial to take
readings after occasional events such as heavy rainfall, particularly
for turbidity checks.
order to substantiate the water monitoring done by MRRCI and that
the data recorded is viewed as accurate, it is important to keep
records of the calibration of all instruments.
monitoring results sheet (MS Word 30k)