1. THE UNIVERSITY OF MANCHE S T E R
FACULTY OF BIOLOGY
“Surv e y of the River Ethero w ”
- POLLUTION DAMAGE -
By: Alvaro H. Pescador R.
To: Dr. Keith White
MSc.POLLUTION AND ENVIRONMENTAL
CONTROL
MANCHESTER - 1996
2. SURVEY OF THE RIVER ETHEROW
OBJECTIVES
By analysing the physical, chemical and biological characteristics of samples
collected at different points of the river, the porpoise of this survey is to look
to organic pollution in fresh water quality, as well as the pollution caused by
heavy metals, studying the impact of the pollutants on the river’s
invertebrates biota.
This survey, looks on the one hand to key physical parameters of a running
water such as flow, temperature (which determines the water density and
influences its conductivity), and the river’s substract, that allows different
species of invertebrates to live inside it. The flow and the temperature were
established directly at each one of the sites that were monitored (1 to 9),
whereas the invertebrates were taken by the kick-sampling technique, once
the sample was taken they were killed and preserved “fixed” in a 4% water
solution of formaldehyde.
On the other hand, chemical parameters that influences the biota of the river
such as the BOD (Biochemical Oxygen Demand), the dissolved Oxygen
and the pH (Hydrogen Potential) were measured as well. Whereas the
dissolved oxygen and the pH can be done directly, the BOD have to be
established at the laboratory five days after the sample has been taken.
Being this a biological surveillance, one of the main objectives is to study
the invertebrates community of the river in order to establish the quality of
3. the water, through the determination of the BMWP (Biological Monitoring
Working Party Score) and the ASPT (Average Score per Taxa).
Some other parameters such as the total hardness were determined as well.
These, the heavy metals tests and the ammonia concentration are key
indicators to establish whether the water is potable or not.
1. IMPACT OF ORGANIC POLLUTION ON WATER QUALITY
The Table 1 provides the physical and chemical parameters that were
measured in order to analyse the current impact of organic pollution on the
river. The table shows the mean value between the samples taken on
November 15th an November 22nd of 1995. When there was only one data
available, as in the case of the BOD (the test were not established for the
samples taken on the 15 th of November) the value that appears was the
only one available.
The suspended solids, the dissolved oxygen, the temperature of the water
(which influences the maximum amount of dissolved oxygen in the water),
the BOD, and the pH are the key parameters that allow us to measure the
impact of the organic pollution on the water quality. In table 1, these values
appears, except the one for suspended solids, for all the sites that were
monitored, (site number 7 was not) in agreement with the map that appears
in Appendix 1.
TABLE 1 - ORGANIC POLLUTION INDICATORS
4. Parameter/Site S1 S2 S3 S4 S5 S6 S8 S9
Temperature (°C) 8.5 9.6 10.3 9.5 9.5 9.6 9.9 14.4
Dissolved O2 (mg/l) 17.6 17.3 18.1 17.4 12.6 12.1 19.5 15.8
Saturation of O2 % 88% 84% 86% 85% 61% 58% 93% 67%
BOD (mg/l) 6.5 1.5 1 7.8 1.6 2.6 15.9 6.4
pH (pH units) 5.4 7.5 7.4 7 7.4 7.5 7.3 7.1
Phosphate (mg/L) 0.01 0.03 0.06 0.06 0.07 0.5 0.04 0.04
Ammonia (mg/L) 0.08 0.04 0.06 0.05 0.07 0.04 0.05 0.05
Nitrate (mg/L) 0.90 0.75 1.15 1.66 1.24 1.12 3.16 0.41
Chloride (mg/l) 1.7 1.1 2.1 1.3 1.6 2.2 2.0 1.2
The Saturation of O2 as percentage has been obtained in agreement with the
ideal value (100% of saturation) that should be in the water at the
temperature given1
. The values are taken for an atmospheric pressure of 1
atm, the deviation is to little to be taken into account since none of the sites
is more than 1000 meters of altitude from the level of the sea (1 atm).
In agreement whit Ellis2
we can classify the river (classes 1 to 4) for the
quality of key values such as the Dissolved oxygen, the BOD5 and the
Ammonia concentration by using the next criteria:
1A: good quality:
Dissolved Oxygen: Saturation grater than 80%
BOD (five days): Not grater than 3 mg/l
Ammonia concentration: Not grater than 0.4 mg/l
1B
Dissolved Oxygen: Saturation between 60-80%
BOD (five days): Not grater than 5 mg/l
1
PERRY, Jhon, “Chemical Engeeniers’ Handbook”, New York, McGrw-Hill, 4a
ed.,
1963, p. 6-138.
2
ELLIS, K.V., “Surface Water Pollution and its Control”, London, Macmillan Press
Ltd., 1989, p. 109-113.
5. Ammonia concentration: Not grater than 0.9 mg/l
2. Fair quality
Dissolved Oxygen: Saturation between 40-60%
BOD (five days): Not grater than 9 mg/l
Ammonia concentration: Grater than 0.9 mg/l
3. Poor quality
Dissolved Oxygen: Saturation between 10-40%
BOD (five days): Not grater than 17mg/l
Ammonia concentration: Grater than 0.9 mg/l
4. Bad quality
Waters which are inferior to class 3 in terms of dissolved oxygen and likely
to be anaerobic at times.
In agreement with this, in terms of oxygen, From table 1 we could classify
sites 1 to 9 of the river Etherow as follows:
Good quality, 1A: Sites 2 and 3.
Good quality, 1B: Sites 1 and 5.
Fair quality: Sites 4, 6 and 9.
Poor quality: Site 8.
FIG 1. ORGANIC POLLUTION: SATURATION OF O2 %
6. 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
S1 S2 S3 S4 S5 S6 S8 S9
Saturation of O2 %
In spite of the high percentage of saturation of O2 in site 8 (93%), THE
HIGHEST of all the sites, the poor quality of the water is given for the high
value of the BOD5 obtained at the laboratory (Fig 2).
Fig 2. BOD (mg/l)
0
2
4
6
8
10
12
14
16
S1 S2 S3 S4 S5 S6 S8 S9
BOD (mg/l)
Perhaps there has been a mistake during the lecture of the dissolved O2 at
site 8 in the river, or the sample for the BOD could have been received some
other external influence (and therefore to be spurious). It is estrange to find
this high level of BOD (15.9 mg/l) in a place with such a high amount of
dissolved oxygen (19.5 mg/l).
Unfortunately we did not run a test for suspended solids, which is also
useful to establish the amount of organic pollution in the water. Any way, in
7. agreement with the classification stated by Ellis, as has been already
analysed, the pollution by organic material in the river Etherow is not high,
and the quality of the water in the different places that were monitored in
relation with the Oxygen tests is really good, just with the exception of site
8, for the possible reasons already explained.
2. CURRENT IMPACT OF THE ORGANIC POLLUTION ON THE
BIOTA.
In order to establish the current impact of the pollution on the biota, a
biological surveillance using invertebrates as bioindicatiors of the actual
state of the quality of the river has been done. The different taxa of
invertebrates that were identified at the laboratory appears in Table 2.
The BMWP (Biological Monitoring Working Party Score) will be used in
order to establish the quality of the river.
TABLE 2 - OCCURRENCE OF INVERTEBRATES, 1995.
TAXA/SITE BMW
p
Score
1 2 3 4 5 6 8 9
PHYLUM ANNELIDA
Class Hirudinea (leeches)
Glosiphonia complanata 3 0 0 2 1 0 3 14 0
Erpobdella octoculata 3 0 0 26 9 3 0 3 1
Helobdella stagnallis 3 0 0 2 0 0 0 0 0
Class Oligochaeta (worms) 1 0 0 0 38 0 0 0 0
Lumbricidae 1 7 16 0 0 0 0 0 0
Haplotaxidae 1 0 0 1 0 0 0 0 1
Lumbricullidae 1 0 9 0 0 0 0 0 0
10. The data that appears at the bottom of Table 2 is the result of the biological
surveillance on 15 th and 22 th of November, 1995. In the case of sites 5, 8
and 9 there was only available the data on November 15 th and is the one
that appears there. On the other sites, the value of the BMWP is slightly
different for 15th and 22 th at each place. There has been taken the highest
values of BMWP for each site (e.g. in site 1 are 61 and 64 respectively,
therefore 64 is the one that appears here) as the current BMWP score of the
site. These results are plot in figure 3.
FIG 3. Current impact of the organic pollution on the biota of the
river Etherow.
0
10
20
30
40
50
60
70
80
S1 S2 S3 S4 S5 S6 S7
BMWP
As can be seen from Fig. 3, the quality of the water decreases steadily
downstream from site 1 to site 4 where the BMWP score reaches its lowest
level (28), this is the place where the Zn leachate is located. Then, the
quality of the water increases from site 4 to 5, after the junction of the river
Glossop, there, the BMWP reaches a value of 39. Among other things, the
increasing of the quality of the water in site 5 is due to the good quality of
11. the water of the river Glossop in site 8, just before the linking to the
Etherow (BMWP=63). Finally, the quality of the water increases with the
distance downstream from site 5 to 7 (the data used for site 7 has been
calculated using Appendix 7, BMWP=76, in 1992).
The relationship between the BMWP Score, the typical biota and river
designation is given in the table 3.
Table 3. BMWP and river designation
TYPICAL BIOTA DESIGNATION BMWP SITE
Salmonis,Plecoptera,
Tricoptera, Amphipoda
Good Quality + 70
Coarse fish
All above group resticted
except Anphipoda and
Baetidae
Fair Quality 30-70 1,2,3,5,6,8
Few fish
Few Tricoptera&Baetidae
Asellus dominant.
Poor Quality 3-40 4,9
Very few fish if so.
Few or no Asellus
Chironomus dominant
Bad Quality 1-3
No fish. Oligochetes
dominat or no animals life.
To Bad. 0-1
In agreement with Table 3 and the results plotted in figure 3, sites 1 to 3
and 5 to 6 of the river Etherow have a fair quality (BMWP between 30-70),
the expected biota of the river in this places is summarised in table 3 as well.
On the other hand, the worst condition of the river is found in site 4, with a
BMWP score of 28: poor quality of the water, no fish will be found in this
place and Asellus will be dominant. The river can be classified as to have
good quality downstream from site 7(1992), with a BMWP score of 76.
12. On the other hand, the ASPT, which is not only independent of the sample
size (a larger sample is likely to include more families, inflating the BMWP
score), but also less influenced by the seasons. Mason3
has established that
the Lincoln Quality Index (LQI), inimically derived by Extence et al4
, using
both the BMWP score and the ASPT can be a more accurate way for the
surveillance in agreement with the River Quality Objectives (RQOs).
To standardised the data a X raiting is given for the BMWP scores, whereas
a Y rating is assigned to the ASPT. In agreement with the results, the scores
for the Habitat-poor rifles and pools might be used in the case of the river
Etherow:
Table 4. Standardised Rating for the OQR.
BMWP Score Rating X ASPT Rating Y
121+ 7 5.0+ 7
101-120 6 4.5-4.9 6
81-100 5 4.1-4.4 5
51-80 4 3.6-4.0 4
25-50 3 3.1-3.5 3
10-24 2 2.1-3.0 2
0-9 1 0-2.0 1
The Overall Quality Ranking is derived as:
OQR = (X + Y) / 2
3
MASON C.F., “Biology of freshwater pollution”, New York, Longman Scientific&
Technical, 2a ed, 1995, p. 234-239.
4
EXTENCE, C.A and FERGUSON A.J.D, “Aquatic invertebrate surveys as a water
quality management tool in the Anglian water region”, Regul Rivers 4, 139-146.
13. The table 5 shows the X and Y values that has been obtained using the
BMWP scores and the ASPT at the bottom of table 2:
Table 5. OQR for the rivers Etherow and Glossop
S1 S2 S3 S4 S5 S6 S8 S9
BMWP 64 45 42 28 39 47 63 39
Rating X 4 3 3 3 3 3 4 3
ASPT 5,5 5 4.2 4 4,3 5 4,5 4,3
Rating Y 7 7 5 4 5 7 6 5
OQR 5.5 5 4 3.5 4 5 5 4
The Overall quality ratings with their equivalent Lincoln Quality Index
values and interpretation of results are shown in table 6.
Table 6. OQR of the rivers Etherow and Glossop
OQR Index Interpretation Site
6+ A++ Excellent quality
5.5 A+ Excellent quality 1
5 A Excellent quality 2,6, 8
4.5 B Good quality
4 C Good quality 3,5
3.5 D Moderate quality 4, 9
3 E Moderate quality
2.5 F Poor quality
2 G Poor quality
1.5 H Very poor quality
1 I Very poor quality
The results are also plotted in Fig. 4, which shape is quite similar for the one
shown in Fig. 3 (BMWP scores). As can be seen from the figure in next
page, the OQR decreases steadily down stream from site 1 to site 4 where
14. the quality of the water shows its lowest level (Moderate quality), then the
river Etherow increases the quality of its water steadily downstream,
reaching in site 6 an excellent quality, almost as good as the one of site 1
(located 6.2 Km after its boring, just before of the reservoir).
Fig 4. OQR values of the river Etherow
0
1
2
3
4
5
6
S1 S2 S3 S4 S5 S6
OQR
3. LONG-TERM CHANGES IN THE WATER QUALITY ARISING
FROM ORGANIC POLLUTION.
The Appendix 3 provides information for the same parameters that appears
in Table 1, for sites 2, 4, 6, 7 and 8, for odd years from 1981 to 1991, and in
some cases (2, 4 and 7) until 1995. It can be seen from this data that the
Dissolved Oxygen has been between 10 and 11 (mg/l) during all these years
whereas the percentage of saturation never has been below 80% (just with
the exception of site 2 in 1995, that was 79.1% which is very close to 80%).
15. On the other hand, the BOD5 never has been grater than 6 mg/l during the
last 15 years, and shows its highest values at site 7 as can be seen in table 7
and fig. 5.
Table 7. BOD5 for the last twenty years at site 7.
Year BOD Year BOD Year BOD Year BOD
1973 2.6 1978 2.8 1983 - 1988 2.5
1974 4.4 1979 4.5 1984 - 1989 2.5
1975 4.2 1980 - 1985 3.4 1990 5.2
1976 3.8 1981 3.7 1986 3.3 1991 3.8
1977 3.2 1982 4.3 1987 3.0 1992 2.9
Fig. 5. BOD5 in site 7 from 1973 to 1992.
0
1
2
3
4
5
6
73 81 91
BOD
As the highest BOD5 during the last years has happened in this site, and this
is an index of organic pollution, it will be interesting to study what has been
the impact on the biota in this place. Having in mind that site 7 measures the
quality of the water of the river Etherow before entering to the river Goyt
that in turn joins the Tame in Stockport, it is interesting as well to study
what has been the impact of the organic pollution on the biota at the end of
16. the river (site 7). Table 8 shows the occurrence of invertebrates in this site
from 1970 to 1992. At the bottom of the table the BMWP score and the
ASPT have been computed in each case.
Table 8. Occurrence of invertebrates at site 7 from 1970 to 1992.
TAXA / YEAR BMWP 1970 1975 1980 1985 1992
PLATHELMYTHES
Policelys sp. 5 3 0 0 0 1
ANNELIDA
Oligochaeta
Glosiphonia complanata
Erpobdella octoculata
1
3
3
3
0
0
3
0
1
3
1
0
3
2
3
3
1
2
MOLLUSCA
Gastropoda
Ancylus fluviatile
Lymnae peregra
Bivalvia
Sphaerium sp.
7
3
3
0
0
0
0
0
0
0
1
1
2
2
1
2
2
1
CRUSTACEA
Asellus aquaticus
Gammarus pulex
3
6
2
0
2
0
3
0
4
1
2
2
INSECTA
Plecoptera
Isoperla grammatica
Leutra sp.
Nemoura sp.
10
10
7
1
0
0
0
0
0
1
1
1
0
0
1
0
0
1
TAXA/SITE BMWP 1970 1975 1980 1985 1992
INSECTA (Cont.)
Ephemeroptera
Rhithrogena semicolorata
Ephemerella ignita
Baethis rhodani
10
10
5
0
0
3
0
0
3
0
0
2
1
1
1
0
1
1
Coleoptera
17. Dytiscidae 5 0 0 0 1 1
Tricoptera
Rhyacophila dorsalis
Polycentropus sp.
Hydrospsyche siltalai
Limnephilidae
7
7
5
7
0
0
0
1
2
0
1
2
2
0
0
0
2
2
2
0
1
1
2
0
Neuroptera
Sialis sp. 4 0 0 0 0 1
Diptera
Simulidae
Chironomidae
Tipulidae
5
2
5
0
4
0
3
3
1
3
2
1
1
2
1
1
3
0
BMWP 36 43 64 99 88
Rating X 3 4 4 5 5
ASPT 4.4 4.3 4.9 5.2 5.0
Rating Y 5 5 6 7 7
OQR 4 4.5 5 6 6
As can be seen from the results, the quality of the river has been improving
from 1970 to 1992, the BMWP and the ASPT have been increasing almost
steadily, and therefore the OQR shows a continues recovering from the
organic pollution that river Etherow have achieved during the last 20 years.
This behaviour of recuperation can be seen clearly in Fig. 8.
Fig 8. Overall Quality Raiting showing the recovering of the river
Etherow from Organic Pollution between 1970 and 1992.
18. 0
1
2
3
4
5
6
1970 1975 1980 1985 1992
OQR
Since 1985 the water have achieved an excellent quality in agreement with
the interpretation given to the OQR, already described in table 6. This
excellent quality remained steady in 1992. Site 7 (Fig. 8) shows the long-
term recoverance of the river Etherow just before of the junction to the river
Goyt and therefore, the impact of the organic pollution on the biota at the
end of the river, as well as the impact that the Etherow will have in the
quality of the water of the river Goyt which in turn joins the Tame at
Stockport.
4. IMPACT ON HEAVY METAL POLLUTION ON WATER
QUALITY AND THE BIOTA.
Table 9 shows the mean values of the concentration of heavy metals, the pH,
and Total Hardness that were measured from site 1 to 9 on 15 th and 22th of
November, 1995.
Table 9. Heavy Metal Concentration in the rivers Etherow and
Glossop
Parameter or Metal/Site S1 S2 S3 S4 S5 S6 S8 S9
19. Temperature (°C) 8.5 9.6 10.3 9.5 9.5 9.6 9.9 15.8
pH (pH units) 5.4 7.5 7.4 7 7.4 7.5 7.3 7.1
Conductivity (uS) 504 60 90 110 198 213 209 131
Copper (µg/l) 5 3 2.5 1.5 15 13.3 14.5 9.5
Zinc (µg/l) 55 31 21.5 31 46.5 53 55 50.5
Total Hardness (mg/l) 28 39.6 46.3 51 67 77 73 56
It is quite important to look to heavy metals due to they are conservative
pollutants, they do not break down and therefore they effectively become
permanent additions to the aquatic environment. They accumulate in
organisms and some may biomagnify in food chains.
The heavy metals of most widespread concern to human health are mercury,
cadmium and lead5
. Nevertheless copper and zinc belong to the “Gray List
Compounds” of the EEC. Fishes like salmon are more tolerant to zinc than
to copper, the incipient LC50 has been estimated at a concentration of 50 µg/l
for copper and 600 µg/l for zinc.
Table 10 show the presence of these metals in the rivers Etherow and
Glossop, whereas in figure 8 we can se the concentration down stream the
Etherow.
Fig 8. Concentration of zinc and copper downstream the Etherow
5
MASON, E.G., Ibid at p. 168.
20. 0
10
20
30
40
50
60
S1 S2 S3 S4 S5 S6
Copper ( g/l)
Zinc ( g/l)
It is really estrange that the river has a high concentration of zinc in site 1,
most probably the data at this site must be spurious. Any way it is
interesting to see that the concentration of zinc increases steadily from site 3
to site 6. The impact of the zinc leachate at site 4 is observed as the
concentration of zinc increases downstream in sites 5 and 6.
On the other hand, the concentration of copper is not as high as the one for
zinc, but copper has a more lethal effect upon the organisms than zinc. For
salmon, the incipient LC50 has been estimated to be a concentration of 50
µg/l for copper and 600 µg/l for zinc. As it is shown in Fig. 8, the highest
concentration of copper (15 µg/l at site 5) and the highest concentration of
zinc (55 µg/l at site 6) are below the incipient LC50 for the salmon.
It is important to see as well that the pH influences the toxicity of the metals.
If there is a little change in speciation and metal binding is weak at the
biological surface as in the case of zinc and copper, the toxicity of the metal
decreases when the pH decreases as well, due to competition for binding
sites from hydrogen ions. Figure 9 shows the pH condition of the river
Etherow.
21. Fig. 9. Hydrogen Potential of the river Etherow
0
1
2
3
4
5
6
7
8
S1 S2 S3 S4 S5 S6
pH (pH units)
As can be seen from figure 9, just with the exception of site 1 which shows
an acid level of pH (5.3), the pH increases downstream from site 1 to site 2
reaching a condition very close to the desirable neutral pH (7) for potable
water. This condition remains almost steadily through out the river; we can
say that the pH levels of the river are really good.
Impact on the river biota due to heavy metals pollution
Species diversity in metal-polluted water is reduced, but tolerant species can
be very abundant. Some species of invertebrates that are very sensitive to
organic pollution, such as stoneflies and casselies caddies, are tolerant to
heavy metal pollution.
Whereas copper affects the photosynthesis of some algae like cyanobacteria,
a concentration of 0.1 mg/l reduces the photosynthesis by 80% in Sprirulia
22. Plantesis, bioaccumulation occurs in the moss Fontinalis squammosa,
which concentration factor is 22.000 for zinc.
There is not doubt that the presence of Zinc in the food chain is the major
reason why site 4 has the worst biological indicators of the river Etherow
(BMWP=28, ASPT=4 and OQR=3.5) which in agreement with the BMWP
score can be interpreted as “poor condition” as was showed in table 5 and
figure 3, or as “moderate quality” (Index D in the equivalent Lincoln Quality
Index) as showed in table 6 and figure 4.
Therefore, it is necessary to be aware of the leaching of Zinc that steel
happens in site 4 because it is the major responsible for the depression in
the quality of the water of the river, and absence of fish in sites 4 and 5. The
presence of copper has to be carefully monitored as well, due to its incipient
LC50 on salmons is just of 50 µg/l.
On the other hand, in order to establish whether the water could be potable
or not, it is important to look to the Total Hardness quality of the water. The
values of table 10 appears plotted in figure 10.
Figure 10. Total Hardness in the water of the river Etherow.
23. 0
10
20
30
40
50
60
70
80
S1 S2 S3 S4 S5 S6
Total Hardness (mg/l)
Figure 10 show us that the amount of ions of Ca++
and Mg++
in the river
Etherow increases steadily downstream. The highest values occurs once the
Glossop has joined the Etherow in sites 5 and 6. There is not doubt that the
total hardness in the water of the river Glossop (73) has a big influence in
the increment of the hardness in the water at site 5 of the river Etherow. In
agreement with its hardness the water could be potable, but the
concentration of Ammonia, the BOD tests and the presence of metals such
as zinc and copper do not allow us to reccomend Ehterow’s water as a
drinking one.
CONCLUSIONS
The use of invertebrates in biological surveillance is very helpful to monitor
the quality of running waters and work out Environmental Impact
Assessment for organic pollution and/or sewage pollution, but some species
that are very sensitive to organic pollution such as stoneflies and casselss
cadis are more tolerant to heavy metal pollution. The cladophora algae is
24. sensitive to zinc and can be used to monitor it, cladophora ausence could be
an indicator of heavy metal pollution.
As an empirical method, the Biological Monitoring Working Party score has
a degree of error due to the size of the samples and to changes in the
invertebrates population throughout the seasons of the year. These errors,
can at least be standardised using the ASPT as well as the OQR that may be
derived using both, the BMWP and the ASPT.
In agreement with biological survilliance and the chemical analysis mainly
sumaraized in tables 5 and 6, and clearly shown in figures 3 and 4, we can
synthetize the surveyllance clasifying each part of the river in agreement
with the NRA system, as it is show in table 12 of the next page.
Ussing the map that appears in Appendix 1, and looking to the distances
from one site to another, we can establish the conditions of the water in the
river Etherow in amount of Kilometers without taken into account the
distance of the Londendale Reservoir.
Fig 12 NRA Quality System applied to the river Etherow
WATER
QUALITY
CLASS SITE Distance
(Km)
POTENTAIL USES
Good quality 1a Water of high quality suitable for
potable supply abstractions and
other abstractions; game or other
high class fisheris; high amenity
value.
Good quality 1b 1,2,7*
7.5 Usuable for substantially the
same purposes as class 1a but
water of lower quality.
25. Fair quality 2 3,5,6 8.5 Water supporting reasonably
good coarse fisheries; water
suitable for potable supply after
advanced treatment; moderate
amenity value.
Poor qualituy 3 4 1.4 Waters which are polluted to an
extent that fish are absent or only
sporadically present; may be used
for low grade industrial
abstraction purposes. Considera-
ble potential for further use ir
cleaned up.
Bad quality 4 Waters which are grosly polluted
and are likelly to cause nuisance
----
*
This value comes from the survey of 1992 in site 7.
Finally, we can have a look to the water quality of the river Etherow as it is
shown in the figures 10 and 11.
Figure 10. The Quality of the water of the river Etherow
43%
49%
8%
Class 1b: 7.5 Km = 43%
Class 2: 8.5 Km = 49%
26. Class 3: 1.4 Km = 8%
Figure 11. The Class of the river Etherow in Kilometers.
0
1
2
3
4
5
6
7
8
9
Km
1b 2 3
APPENDIX 1. MAP OF THE RIVER ETHEROW
