WATER QUALITY
Trout and other aquatic
creatures that live in our
lakes require good quality
clean water in order to
survive, with an adequate
amount of oxygen dissolved
in the water probably being
the most important factor in
determining their wellbeing,
although other factors, for
instance, nitrate and
phosphate levels can have an
effect. The question of the
pH levels of our waters has
been raised in the past as
our stock fish come from a
supplier whose water has a
high value. The pH is a
measure of the acidity or
alkalinity of the water, a
low number being acid,
higher numbers more
alkaline, with pH7 being
neutral. Fortunately trout
are fairly tolerant of the
pH levels and can survive
quite well in low values,
although waters with lower
levels will not produce the
weed growth and invertebrate
numbers to provide adequate
food for the fish which
therefore tend to be small
in consequence. A high pH on
the other hand, leads to
plentiful weed and
invertebrate life for fish
to feed on and they do
better and grow larger in
such waters. Measurements of
the pH in our lake
waters in 2012 gave an
average value of around
pH7.5, which is fine, being
much the same as rainwater
and there is no reason to
suppose that it will have
changed very much since
then.
In the summer months at times of
high air temperatures and with
little rain to refresh the
waters, we make measurements of
the temperature and dissolved
oxygen levels of the water in
the lakes, which is important in
ensuring the survival of our
expensive stocked fish, and
if conditions are particularly
poor delay or postpone any
additional stocking until things
improve.
Measuring this dissolved
oxygen is a good indicator
of water quality; however
the level will change, not
only from season to season
or day by day, but even
hourly, dependant on several
varying factors.
Water temperature has a
significant effect on the
dissolved oxygen level, the
higher the temperature the
less oxygen can be held in
solution. At standard
pressure, at sea level,
fully saturated pure fresh
water, can have a maximum
dissolved oxygen level at
zero oC of 14.6
milligrams per litre; at 5oC
12.8 mg/l; at 10oC
11.3 mg/l, at 15oC
10.1 mg/l, at 20oC
9.1 mg/l and at 25oC
8.2 mg/l. Atmospheric
pressure also plays a part,
high pressure leading to
higher levels while low
pressure allows the oxygen
to escape, much the same
effect as one sees when
opening a bottle or can of
fizzy drink, when the
pressure is suddenly reduced
and the carbon dioxide
previously held in solution
instantly explodes.
Decaying plant or animal
matter and pollution all
consume oxygen as they
degrade which can lead to
disastrous consequences,
particularly when hot
weather and low pressure
combine. Chemical salts
dissolved in the water also
reduce the level, which is
why seawater holds less
oxygen than fresh.
Although it behaves like
most other fluids, which
increase in density the
colder they are, eventually
freezing into their solid
form, water is a funny old
substance, being unusual as
its maximum density occurs
at 4oC, while it
is still in a liquid state.
Hence in still water, when
the air temperature is lower
than the water temperature,
the surface layers are
cooled and as a consequence
they sink, being replaced by
warmer water, which again
cools and sinks. In really
cold conditions, with air
temperatures at or below 4oC,
this process will be
repeated, until eventually
all the water in the lake is
at this temperature. Should
the weather conditions
remain below 4oC
for a further period, the
surface layers will then
cool to below this level,
becoming less & less dense
the colder they get, yet
still remaining at the
surface, which is why, when
air temperatures drop to
zero or below, ice forms at
the surface. Water is a
relatively poor
conductor of heat, so while
the surface layers could be
at zero or even lower, a few
inches down the water
temperature may still be 4oC .
Obviously, the longer the
cold spell the greater the
cooling effect on the
surface layers and the
thicker the ice, but one
wouldn’t need to go very
deep to find the 4oC
level. Being a cold water
fish, rainbow trout are
quite happy in such
conditions and can still
provide good sport even when
ice is covering the water.
However, when air
temperatures increase above
the 4oC mark, the
surface layers are heated,
become less dense and
therefore, in still water,
without significant wind or
wave action, remain at the
surface and dependant on the
air temperature, become
warmer all the time, with as
a consequence, a much
reduced oxygen content,
while a little deeper it is
still much cooler with a
good oxygen levels. Indeed,
some very deep lakes,
provided water movement is
minimal, may have areas
where the water temperature
remains a constant 4oC
all the time, although the
oxygen content at these
depths may well be depleted.
This might also explain why
trout tend to go deeper in
hot bright weather, as they
seek the best oxygen
conditions, rather than the
idea that as they have no
eyelids they don’t like the
brightness. During high
summer, with bright sunlight
conditions and high air and
water temperatures, the fish
will tend to seek these
deeper areas, lying doggo
and not really interested in
our flies, the best chance
of any success being either
early morning or late in the
evening when conditions are
cooler and light values much
lower.
Rainbow trout are happiest
when the water temperature
is around 10oC ,
grow best around 15oC
and become uncomfortable at
20oC ,
temperatures higher than
this proving fatal.
Oxygen gets into the water
in several ways. Some is
absorbed at the water / air
interface, where wind and
wave action also improve
matters and although rain
helps, much of the remainder
is produced by
photosynthesis of the plants
and algae present in the
water, which produce oxygen
during daylight hours, but
unfortunately also absorb
oxygen and release carbon
dioxide during the night.
As a consequence of this photosynthesis, given
adequate daylight, the
dissolved oxygen level will
be highest in the early
afternoon and at their
lowest at first light, when,
even if daylight readings
appear adequate, the dawn
levels may well be below
that necessary to ensure
survival of our fish. For
this reason, when conditions
are suspect, dissolved
oxygen tests should be
carried out at the crack of
dawn. A level of 4mg/l is
the absolute minimum
required by our trout, which
require higher levels than
many coarse fish, notably
carp and tench, which can
survive when the dissolved
oxygen is as low as 2mg/l.
In the past, our good
friends of the Ouse and Adur
Rivers Trust have carried
out occasional water quality testing of our lakes,
providing results for
several different
parameters, including
dissolved oxygen and
temperature.
However, these
tests are all relatively
expensive, quite time
consuming and as the tests
are carried out off site and
some time after water
samples are taken from the
lakes, there is a possibly
of changes occurring during
this delay period. It
is also not practical to
make frequent checks on a
regular basis.
We
therefore purchased
our own dissolved oxygen
meter and although a relatively
inexpensive piece of kit,
this has enabled us to make
regular checks of oxygen and
temperature and postpone
stocking should water
conditions suggest that it
would be unwise.
Water temperature readings
are made on the bottom in
about 3 to 4 feet of water.
At the surface they are
usually some 2 or 3 degrees
or so higher and one would
expect them to be a few
degrees cooler the deeper
one goes. Dissolved oxygen
readings are made at the
surface as one needs to keep
a flow of water across the
sensor probe to obtain a
valid measurement.
The results of Water Quality
checks on the lakes are shown
below.
8th August 2024 -
Water Quality Results
During
the warm summer
months,
without
any
worthwhile
rain to
speak
of,
since
the
beginning
of June, our
worthy
Chairman
Kevin
Reeves
has
been monitoring
the
water
quality
of all
the
lakes,
taking
readings
for the
water
temperature
and
dissolved
oxygen
levels,
as
temperatures
above 20
degrees
C are
uncomfortable
for
trout
and can
be fatal
at 25,
the
readings
generally
being
made at
a depth
of
around
120mm
below
the
surface.
With in
general
daytime
temperatures
below
normal
for the
summer
months,
water
temperatures
have
been
below
the 20
degrees
C mark
and
until
recently
there
has been
some
flow in
the
feeder
streams,
with
dissolved
oxygen
levels
remaining
more
than
adequate
for the
welfare
of the
fish.
However
a warm
spell at
the end
of June,
with air
temperatures
in the
mid to
high
twenties,
resulted
in water
temperatures
over 20
and
although
oxygen
levels
remained
good,
stocking
was
suspended.
Temperatures
then
dropped,
but
then, at
the end
of July,
we have
had heatwave
conditions
for a
couple
of days,
with air
temperatures
in the
mid to
high
twenties,
virtually
no flow
in the
feeder
streams
and
water temperatures
climbing
as high
as 22.4oC.
Thankfully
oxygen
levels
have
remained
adequate
and as
far as
we know,
there
have
been no
fish
lost.
Since
then, on
the 1st
August,
we had a
serious
amount
of rain
in a
short
time in
the area,
resulting
in flash
flooding
at
Cinder
Hill as
reported
in the
Notices
Page and
we will
have to
wait and
see what
effect
this
will
have on
the
lakes
when
everything
has
settled
back down..
Water Quality Results 2023
Throughout
the hot
dry
summer
months,
without
any
worthwhile
rain to
speak
of,
commencing
in May,
our
worthy
Chairman
Kevin
Reeves
has
monitored
the
water
quality
of all
the
lakes,
taking
readings
for the
water
temperature
and
dissolved
oxygen
levels,
as
temperatures
above 20
degrees
C are
uncomfortable
for
trout
and can
be fatal
at 25,
the
readings
generally
being
made at
a depth
of
around
120mm
below
the
surface.
During
May.
both
parameters
were
well
within
limits,
the
highest
water
temperature
of
18.4oC
being
recorded
in the
top lake
at
Piplye,
while
the
lowest
oxygen
level
was
6.7mg/l
in the
bottom
lake,
again at
Piplye.
In June,
when
daytime
air
temperatures
reached
as high
as 27oC
and with
virtually
no flow
in the
feeder
streams,
things
were
somewhat
different,
with
water
temperatures
in all
the
waters
exceeding
20oC,
reaching
a high
of
25.6oC
in the
bottom
lake at
Cinder
Hill,
with the
result
that
oxygen
levels
were
much
reduced,
the
lowest
recorded
being
just
3.4mg/l,
again in
the
bottom
lake at
Piplye,
with the
reading
varying
between
4 and
7.5mg/l
on all
the
other
waters.
As a
consequence,
although
very few
fish
died and
fish
were
being
caught,
no fresh
stock
were
introduced
in
Piplye
and
catch
and
release
fishing
was
stopped.
Similar
conditions
carried
on
through
July,
with the
water
temperature
remaining
around
the 20oC
mark and
oxygen
levels
generally
around 6
to 8
mg/l,
apart
from the
bottom
lake at
Piplye,
although
the
weather
did cool
off a
bit and
there
was some
rain
towards
the end
of the
month,
the
colder
water
leading
to an
increase
in
oxygen
levels.
At the
beginning
of
August
we had a
couple
of days
with
very low
barometric
pressure
and
quite a
bit of
rain,
giving
some
increase
in the
flow of
the
feeder
streams,
but the
water
temperatures
remained
around
the 20oC
mark,
although
oxygen
levels
remained
adequate,
but we
did lose
a few
fish
early in
the
month,
possibly
due to
the
sudden
pressure
reduction
and
resultant
drop in
dissolved
oxygen.
Then, at
the
start of
September,
we had
another
heat
wave and
water
temperatures
climbed
to some
2 or 3
degrees
above
the 20oC
mark,
yet
despite
the flow
in the
feeder
streams
all but
drying
up, the
oxygen
levels
remained
O.K. at
between
5 and 8
mg/l,
although
fish
were
seen to
be in
distress
at
times.
Come
October,
although
flow in
the
feeder
streams
remained
minimal,
cooler
weather
allowed
the
water
temperatures
to drop
to
around
17oC,
with
oxygen
levels
around 6
to 7mg/l
in all
the
lakes.
The
readings
were
mostly
made mid
morning
or
around
mid day,
after
the sun
had been
shining
for
several
hours
and it
was
noticeable
that the
higher
oxygen
readings
came
from the
waters
having a
lot of
weed
growth,
where
photosynthesis
was
taking
place,
while
the
lowest
values
more
often
than not
came
from the
bottom
lake at
Piplye,
where
there is
little
weed and
no doubt
the
presence
of the
carp
have a
significant
effect.
Had the
measurements
been
made at
first
light,
one
would
expect
the
oxygen
levels
in the
weedy
waters
to be
much
lower as
reverse
photosynthesis
takes
place
overnight,
the weed
then
absorbing
the
dissolved
oxygen
and
releasing
carbon
dioxide.
Never
the
less, we
got away
fairly
lightly
as far
as fish
losses
were
concerned
compared
with
some
other
fisheries,
but the
trend of
hot, dry
summers
is
perhaps
something
we shall
have to
get used
to as
global
warming
takes
effect.
17th
September 2022 - Stocking Resumed
Cinder Hill lakes are now
stocked and conditions look
much more favourable than in
recent weeks when water
quality was too poor to
introduce new fish. Piplye
will be stocked later next
week.
Although we experienced some
fish fatalities during the
heatwave, we fared well
compared to some other trout
fisheries and there are
still fish in most lakes
that survived the summer
conditions, most notably the
top lakes at Piplye and
Cinder Hill, so there should
be some good fishing from
now on.
Conditions are now good to
enable us to resume our
regular stocking plan until
the end of the season.
Tight lines,
Kevin Reeves,
Chairman.
Water Quality Results 2022
Water Quality & Stocking Update,
5 September 2022
This
year we
have
seen and
experienced
the
hottest
summer
since
1976
with
record
high
temperatures
and as
we all
know
this has
had an
effect
on our
lakes .
We
advised
recently
that
Cinder
Hill
middle
lake had
lost a
number
of fish,
and this
is
currently
closed
until
the
situation
improves.
The
bottom
lake at
Cinder
Hill has
a lot of
blue/green
algae
and
shouldn't
be
fished
either.
However,
there
are
still
fish in
all of
the
other
lakes,
but they
will be
hard to
catch
under
current
conditions.
Current
water
temperatures
are
hovering
around
19-21
degrees
C, still
too
dangerous
to
introduce
new
stock.
The
recent
rainfall
has
helped
to
re-oxygenate
the
water
and
start to
show
positive
improvements
and with
more
rain
forecast
for this
coming
week in
conjunction
with
cooler
nights
and
lower
daytime
temperatures
we can
only
hope
conditions
will
further
improve.
Please
be
assured
that we
are in
regular
contact
with our
stockist
and are
aiming
hopefully
to
introduce
some
fresh
fish in
just
under 2
weeks
time if
conditions
allow.
Water Quality Report,
21 August 2022
Due to the
continued dry
weather and high
temperatures,
the lakes have
deteriorated
further since
the last report.
Even the recent
heavy rain and
thunderstorms
over Horsted
Keynes have not
improved
conditions very
much, although
there is now a
trickle of water
over the splash
at Cinder Hill
where it had
been completely
dry. This has
helped a little
with the top
lake but there
is no flow into
the middle or
bottom lakes.
We have been
conducting water
quality checks
every 2 or 3
days since the
hot weather
began and over
the past few
days checks have
been carried out
daily. The
middle lake at
Cinder Hill is
of particular
concern as the
water is a muddy
brown colour
with very little
oxygen, so
little in fact
that we have
seen a high
number of trout
deaths in that
lake. We
therefore advise
that fishing in
the middle lake
is suspended
until further
notice. Fishing
in the top and
bottom lake is
currently
possible but the
expectation is
that you will be
lucky to catch
even one fish at
the moment.
The top and
middle lakes at
Piplye are
faring better.
The water is
fairly clear and
we have seen
trout foraging
in the margins.
We have also
seen one or two
dead trout but
this is quite
common during
these hot and
dry summer
months.
Let us hope that
we get some
decent rainfall
before too long
to freshen up
the lakes such
that we can
recommence
stocking.
Water Quality Report,
1 August 2022
Further checks were made on the
23rd and 24th July with air
temperatures now much lower at
around 21oC.
With still no rain, there is no
water flow through the lakes and
water levels on some of the
waters are some 12 to 14 inches
below where they should be.
Water temperatures have been
measured at between 22.7oC
and 25.8oC,
with dissolved oxygen between a
low of 4.4mg/l in the middle
lake at Cinder Hill, to the
highest at 9.3mg/l in the top
lake at Piplye.
We have suffered one or two
losses, but so far the fish seem
to be surviving O.K.
Water Quality Report,
21 July 2022
With all the hot weather we are now experiencing and with no rainfall for
weeks there is no flow through
the lakes, those at Cinder Hill
taking on a brown tinge while
those at Piplye are faring a
little better with fairly clear
water despite the lack of flow,
so frequent checks of the water
quality in all the lakes have
been carried out at regular
intervals.
With strong sun and air temperatures at times approaching 40oC, it is no surprise that we have measured water temperatures of up to
26.4oC at the surface, with it a couple of degrees or so lower at depth.
Fortunately dissolved oxygen levels have remained o.k. apart from the
middle lake at Cinder Hill on
the 15th July when the measured
reading dropped to 3.9mg/l,
which could prove fatal to trout
and the aerator was deployed
twice to try and improve the
situation. Thankfully by the
17th the level had increased to
a safer 7mg/l. The latest
readings made on the 20th,
following two days of extreme
air temperatures, were
surprisingly very similar to
those reported earlier, as we
were understandingly expecting
far worse, the lowest oxygen
reading at 5.5mg/l again being
on the middle lake at Cinder
Hill, which should still be just
o.k. given a water temperature
of 24.8oC.
As far as we know, we have so far suffered few losses, with the situation
overall is not as bad as we
might have expected and if the
temperatures fall enough over
the next few days we might be
o.k. The issue then will be the
oxygen levels.
We will continue to monitor the
situation closely and keep
members posted on the current
state of play.
We can see from the catch return
sheets that few members have
ventured out during these hot
days and with the hot weather,
the wise members are better off
supping a cold drink in the
shade rather than getting heat
stroke trying for uninterested
trout.
Even when the temperatures drop
and as there has been no rain
for weeks with no flow through
the lakes to refresh the waters,
it will take a long time for the
lakes to cool down.
Once temperatures drop, very
early morning or late evening
should be the best time to try
for a fish or two. Let's hope we
have some cooler weather soon
and a decent amount of rain.
Water Quality Report,
June 2022
With the advent of the warmer
summer weather and very little
real rain to speak of to refresh
the waters and boost the flows
in the feeder streams, regular
checks of water quality in
respect of temperature and
dissolved oxygen have been
carried out on all the lakes at
Cinder Hill and Piplye over the
past two months and the results
are summarized below.
A dissolved oxygen level of 4
mg/litre is the absolute minimum
required for trout to survive,
while water temperatures above
20oC
are uncomfortable
for the species and can be fatal
at 25oC
and above.
In all cases the temperature and
dissolved oxygen readings were
made at approx 120 mm depth and
between the hours of 10:30am to
2:30pm.
During May, with the air
temperature between 18.6 to 20.9oC, there was very little
flow in the feeder streams,
water temperatures varied
between 14.2 and 17.1oC
and the dissolved oxygen varying
from 6.3 to 14.7 mg/litre,
giving no problem for the fish.
Interestingly, both the lowest
and highest oxygen were from the
middle lake at Piplye.
In June, with air temperatures
between 15.3 to 17.1oC,
with again minimal flow in the
feeder streams, those at Piplye
not flowing at all towards the
end of the month, water
temperatures were between 19 and
22.5oC, with the
dissolved oxygen varying from
5.5 to 12.7 mg/litre, the lowest
oxygen readings coming from all
three lakes at Cinder Hill. As a
consequence, all catch and
release fishing was terminated
for this season.
So far we have not seen any
evidence of fish in trouble, but
members are requested to contact
us as soon as possible should
they see signs of fish in
difficulty.
We will continue to monitor
water quality throughout the hot
summer months and no stocking
will take place should we
consider it unwise in view of
the water conditions.
Water Quality Results 2021
Water Quality Report, September
2021
Throughout the summer, regular
water quality readings have been
carried out on the lakes at both
Cinder Hill and Piplye.
Thankfully, apart from two or
three really hot spells, the
weather has generally been on
the cool side and, although it
seems to have come in spasms, we
have had sufficient rain to keep
the ground waters topped up and
the feeder streams flowing.
Water temperatures have
generally remained below 20oC,
aside from the hot spells of
weather in June, July and the
present, with air temperatures
sometimes approaching the high
twenties, when the water
temperature at the surface
reached a high in excess of 25oC
on two or three occasions.
However, at depth, they were
generally some 4 or 5 degrees
lower giving some respite to our
precious fish.
Despite the high water
temperatures at times, the
dissolved oxygen levels have
remained good throughout the
year, never imposing any threat
to the wellbeing of the fish and
as far as we can tell there have
been very few losses.
Water Quality Results 2020
Water Quality Report, 27th
May 2020
Due to all the hot dry weather
we have experienced of late,
with no rain to speak of to
refresh the lakes and little
sign of any change in the
foreseeable future, water
quality readings for all the
Cinder Hill Fly Fishing lakes
were made on the 27th May 2020,
with the following results:
Weather: Dry, 60/40 sun/cloud,
light breeze.
Piplye; Time: 9:40pm, Air
temperature 27oC. Very
little flow in the feeder
streams.
Top Pool: Water temperature 21oC at depth, dissolved oxygen
12.2 mg/l. Water quite coloured.
Water level several inches below
the outlet cill. No sign of
fish.
Middle Pool: 20.3oC at
depth, O2 12.1 mg/l. Quite
coloured. Slight flow, One dead
trout removed from the water.
Bottom Pool: 18.2oC at
depth, O2 12.6 mg/l. Coloured as
usual. Water flowing out of the
outlet monk. One sickly trout on
surface. Carp present as usual.
Cinder Hill; Time:
11:30am, Air temperature 27.3oC. Still some flow in the
feeder stream.
Top Pool: Water temperature 18.8oC at depth, dissolved oxygen
7.7 mg/l. Water clear,
occasional fish showing.
Middle Pool: 20.3oC at
depth, O2 5.5 mg/l. Some colour
in the water. No fish showing.
Bottom Pool: 21oC at depth,
O2 5.6 mg/l. Water clear. Fish
rising.
As usual temperatures at depth
were taken on the bottom in
about 3 to 4 foot of water. At
the surface they were a degree
or so higher and one would
expect them to be a few degrees
cooler the deeper one goes.
While the oxygen levels at
Piplye appear fine, the
temperatures are of some concern
as trout are unhappy when it
gets above 20oC.
At Cinder Hill, apart from the
Top Pool, where conditions still
seem acceptable, the middle and
bottom lakes are a worry, with
higher water temperatures and
very low oxygen readings, as
6mg/l is considered the minimum
for trout to survive, although
the fish don’t seem to know
that, as in the Bottom Pool they
were rising freely taking food
of the surface, with no signs of
distress.
In view of the water conditions,
all catch and release has now
been suspended.
Water Quality Results 2019
Water Quality Report, 13th
August 2019
Weather: Dry, 50/50 sun/cloud,
light westerly breeze.
Piplye; Time: 17:00pm,
Air temperature 23 oC
in shade, Feeder streams
virtually dry.
Top Pool: Water temperature 19.7
oC at depth,
dissolved O2
9.8 mg/l. Water quite coloured,
probably due to carp activity.
Quite a bit of weed showing. No
flow, water level several inches
below the outlet cill. No sign of fish other than the
carp.
Middle Pool: 18.7 oC
at depth, O2
10.8 mg/l. Clear but tea
coloured. No flow, water level
below the outlet monk. No sign
of fish other than one sickly
trout.
Bottom Pool: 19.7 oC
at depth, O2
9.8 mg/l. Coloured as usual.
Surprisingly, water was flowing
out of the outlet monk. No sign
of fish, not even the carp.
Cinder Hill; Time:
18:00pm, Air temperature 19.1
oC in the shade.
Reasonable flow in the feeder
stream.
Top Pool: Water temperature 18.6
oC at depth,
dissolved O2
9.3 mg/l. Water clear,
occasional fish showing.
Middle Pool: 17.9 oC
at depth, O2
8.7 mg/l. Water clear but tea
coloured, no fish showing.
Bottom Pool: 18.2 oC
at depth, O2
7.7 mg/l. Water clear but tea
coloured, no fish showing.
All the readings were taken at
the worst possible time of day,
when both temperature and
dissolved oxygen would be
approaching their highest value
With the cooler weather & rain
we have experienced lately the
temperatures have come down to
levels which should not threaten
the trout & with the forecast
for the next week or so being
for similar conditions, there
shouldn't be any cause for
concern.
Water Quality Report, 11th July
2019
With the hot weather we have
experienced over recent days and
little sign of any significant
rain, water quality checks of
all the lakes were
made on the 11th July 2019, with
the following results:
Piplye; Time: 16:45pm,
Air temperature 23.4 oC
in shade, 50/50 sun/cloud, light
westerly breeze. Feeder streams
dry.
Top Pool: Water temperature 23.8
oC at depth,
dissolved O2
10.1 mg/l. Clear, but scum on
surface. No flow, water level
several inches below the outlet
cill. No sign of fish other than
the carp.
Middle Pool: 20.8 oC
at depth, O2
10.3 mg/l. Clear. No flow, water
level a couple of inches below
the outlet monk. No sign of
fish.
Bottom Pool: 21.2 oC
at depth, O2
12.7 mg/l. Coloured, but not
quite as much as usual.
Surprisingly, water was flowing
out of the outlet monk. No sign
of fish other than the carp.
Cinder Hill; Time:
17:45pm, Air temperature 25
oC in the shade, 50/50
sun/cloud, light westerly
breeze, merest trickle in the
feeder stream.
Top Pool: Water temperature 22.6
oC at depth,
dissolved O2
8.6 mg/l. Water clear, no fish
showing.
Middle Pool: 21.4 oC
at depth, O2
8.5 mg/l. Clear, no fish showing
other than one dead one.
Bottom Pool: 21.2 oC
at depth, O2
7.7 mg/l. Very clear, no fish
showing.
All the readings were taken at
the worst possible time of day,
when both temperature and
dissolved O2
would be approaching their
highest value. Early in the
morning at first light it could
be a different matter with O2
levels 2 or 3 mg/l lower as the
dissolved O2
is absorbed by the weed during
darkness hours to produce CO2.
As was to be expected, water
temperatures have now increased
to the levels when trout,
especially rainbows, which are a
cold water fish, will be feeling
extremely uncomfortable.
Hopefully they will be able to
find cooler water in the deeper
areas of the lakes, where they
will probably sulk, showing
little interest in feeding or
attacking artificial flies.
Surprisingly the dissolved O2
levels appear O.K., although the
values for Cinder Hill are
possibly a bit marginal, as
readings a couple of mg/l or so
lower would put the levels
dangerously close to the
minimum trout need to survive.
